Features, Events, and Processes in UZ Flow and Transport Rev 00, ICN 00

ANL-NBS-MD-000001

March 2000

1. PURPOSE 
Unsaturated zone (UZ) flow and radionuclide transport is a component of the natural barriers that 
affects potential repository performance. The total system performance assessment (TSPA) 
model, and underlying process models, of this natural barrier capture some, but not all, of the 
features, events, and processes (FEPs) that are associated with this natural barrier. This analysis 
and model report (AMR) discusses all FEPs identified as associated with UZ flow and 
radionuclide transport. The purpose of this analysis is to give a comprehensive summary of all 
UZ flow and radionuclide transport FEPs and their treatment in, or exclusion from, TSPA 
models. This analysis will only acknowledge and refer to other documentation for FEPs treated 
explicitly in TSPA models, because detailed discussion of these FEPs exists in other analysis and 
model reports. Other FEPs may be screened out from treatment in TSPA by direct regulatory 
exclusion or through arguments concerning low probability and/or low consequence of the FEPs 
on potential repository performance. Arguments for exclusion of FEPs are presented in this 
analysis. 
This report has been prepared in accordance with the development plan Features, Events, and 
Processes in UZ Flow and Transport  (CRWMS M&O, 1999a).

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2. QUALITY ASSURANCE 
The quality assurance program is applicable to this report. The Performance Assessment 
Operations responsible manager has evaluated this activity in accordance with QAP-2-0, 
Conduct of Activities. The QAP-2-0 activity evaluation (CRWMS M&O 1999b) determined that 
the development of this AMR is subject to the Quality Assurance Requirements and Description 
(DOE 2000) requirements. This report is prepared in accordance with AP-3.10Q, Analyses and 
Models. 
The unsaturated and saturated zone natural barriers have not been classified per QAP-2-3, 
Classification of Permanent Items. However the natural barriers have been classified by 
hydrogeologic units in the current project Q-List (YMP 1998). In this document, the following 
hydrogeologic units in the UZ were identified as important to waste isolation: Tiva Canyon 
Welded, Paintbrush Nonwelded, Topopah Spring Welded, Calico Hills Nonwelded. In addition, 
the saturated zone (SZ) was listed as a natural barrier important to waste isolation.

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3. COMPUTER SOFTWARE AND MODEL USAGE 
No models were developed as part of this AMR. Only results from upstream models were used 
in this analysis, and the relevant input data used in this analysis are listed in Section 4.1. The 
three software routines used in this analysis (as described below) are documented in accordance 
with AP-SI.1Q, Software Management. 
A software routine, ptn_v1.f Version 1, was used to extract the coordinates of the Paintbrush 
Nonwelded hydrogeologic unit in four cross sections overlying the potential repository. The 
listing and documented verification of this software routine is given in Attachment IX. The 
results of this routine were verified by visual inspection. The listing of this routine along with 
the output generated by this routine may be found under DTN: MO9912SPAPTN01.006 in the 
Technical Data Management System. 
A software routine, perch_ele.f Version 1, was used to extract the volumes of water in the 
fracture nodes of the perched water bodies as computed in the UZ flow model. The listing and 
documented verification of this software routine is given in Attachment X. The results of this 
routine were verified by visual inspection. The listing of this routine along with the output 
generated by this routine may be found under DTN: MO9912SPAPWI01.006 in the Technical 
Data Management System. 
A software routine, pflux_rep.f Version 1, was used for calculating the repository-area 
percolation flux and its histogram (the latter function is not used in the present analysis). The 
listing and documented verification of this software routine is given in Attachment X. The 
results of this routine were verified by visual inspection. The listing of this routine along with the 
output generated by this routine may be found under DTN: MO9912SPAPWI01.006 in the 
Technical Data Management System.

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4. INPUTS 
4.1 DATA AND PARAMETERS 
This summary analysis primarily relies on existing documentation for data and analysis. Data 
used directly for analyses in this report are given in Table 1. 
Table 1. Input Data 
Description/ 
Qualification Status 
Data Tracking 
Number 
Comments Section 
Used 
Borehole Locations/ 
Qualified 
MO9907YMP99025.001 Used for locations of deep 
boreholes on the potential 
repository block 
6.2.1 
Coordinates for potential 
repository/ Not qualified 
SN9907T0872799.001 Data for coordinates of 
potential repository used in 
cross-section plots for 
reference only. 
6.3.5 
Mesh/ Not qualified LB990701233129.001 Mesh files used to identify 
coordinates of the PTn for 
cross-sectional plots. 
6.3.5 
LB990801233129.001 Present-day low 
infiltration; perched water 
model #1 
6.7.9 
Flow Field Simulations  
used to compute perched 
water volumes and 
percolation flux at the 
potential repository./ 
Not qualified LB990801233129.002 Present-day low 
infiltration; perched water 
model #2 
6.7.9

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Table 1. Input Data (continued) 
Description/ 
Qualification Status 
Data Tracking 
Number 
Comments Section 
Used 
LB990801233129.003 Present-day mean 
infiltration; perched water 
model #1 
6.7.9 
LB990801233129.004 Present-day mean 
infiltration; perched water 
model #2 
6.7.9 
LB990801233129.005 Present-day upper 
infiltration; perched water 
model #1 
6.7.9 
LB990801233129.006 Present-day upper 
infiltration; perched water 
model #2 
6.7.9 
LB990801233129.007 Glacial transition low 
infiltration; perched water 
model #1 
6.7.9 
LB990801233129.008 Glacial transition low 
infiltration; perched water 
model #2 
6.7.9 
LB990801233129.009 Glacial transition mean 
infiltration; perched water 
model #1 
6.7.9 
LB990801233129.010 Glacial transition mean 
infiltration; perched water 
model #2 
6.7.9 
LB990801233129.011 Glacial transition upper 
infiltration; perched water 
model #1 
6.7.9 
Flow Field Simulations  
used to compute perched 
water volumes and 
percolation flux at the 
potential repository./ 
Not qualified 
LB990801233129.012 Glacial transition upper 
infiltration; perched water 
model #2 
6.7.9 
The data concerning borehole locations, repository footprint location, and unsaturated zone flow 
fields under various climate and perched water scenarios. These data are clearly relevant and 
appropriate information to help analyze the potential effects of boreholes and perched water on 
potential repository performance. The data concerning the geologic cross-sections is relevant to 
the question concerning episodic transient flow because the hydrogeologic units and their 
respective properties clearly play an important role in this process. 
4.2 CRITERIA 
Technical screening criteria used in this analysis are given in DOE's Interim Guidance (Dyer 
1999). According to the DOEs Interim Guidance Section 102(j) (Dyer 1999), if the probability 
of occurrence for a FEP is less than 10-4 per 104 years, then the FEP may be excluded from 
further consideration in the total system performance assessment. In this analysis, events with a 
probability of occurrence less than this magnitude are excluded from further consideration. In

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addition, FEPs may also be excluded from TSPA if they can be shown to have no significant 
effect on expected annual dose. There is no quantified definition of "significant effect" given in 
this guidance. 
4.3 CODES AND STANDARDS 
This AMR was prepared to comply with DOEs Interim Guidance (Dyer 1999) which specifies 
guidance to be used for evaluations in the absence of the NRCs final Yucca Mountain 
regulation. Subparts of this guidance that are particularly applicable to the data in this 
investigation include Subpart B, Section 15 (Site Characterization) and Subpart E, Section 114 
(Requirements for Performance Assessment). Subparts applicable to models are outlined in 
Subpart E, Sections 114 (Requirements for Performance Assessment) and 115 (Required 
Characteristics of the Reference Biosphere and Critical Group).

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5. ASSUMPTIONS 
This AMR either identifies existing analyses that address specific FEPs for TPSA or provides 
justification for why specific FEPs are not addressed in TSPA. Any assumptions that are used in 
referenced analyses are not repeated here; the assumptions used in existing analyses and the 
bases for those assumptions are documented in the referenced analyses. Assumptions used to 
justify exclusion of specific FEPs are listed below along with the basis for these assumptions. 
The section numbers to which these assumptions apply are also identified. 
Assumption 1 (Section 6.2.1) 
Water entering a borehole that penetrates beyond the potential repository would tend to remain in 
the borehole or follow the borehole as a preferred pathway. 
Basis: Flow will tend to follow the existing borehole pathway or enter fractures that are in 
communication with the borehole. All the boreholes are vertical or nearly vertical. Flow within 
the fractures will be dominated by the gravitational gradient, resulting in flow roughly parallel to 
the borehole. Any features that could result in significant lateral flow are rendered ineffective by 
the borehole. This assumption is reasonable and does not require further verification. 
Assumption 2 (Section 6.2.6) 
Boreholes drilled for the Yucca Mountain project are known and other undetected boreholes in 
or close to the repository block are very unlikely to exist at Yucca Mountain. 
Basis: Drilling of boreholes for site characterization at Yucca Mountain are recorded 
(MO9906GP98410.000). Also, given the long and intensive site characterization activities at 
Yucca Mountain, the possibility of an undetected borehole near or in the potential repository 
block is very unlikely. This assumption is reasonable and does not require further verification. 
Assumption 3 (Section 6.2.7) 
Water movement in and around the emplacement drifts is primarily vertical relative to the length 
scale of the emplacement drifts. 
Basis: The only known features at the site that could result in large-scale lateral diversion are the 
perched water bodies. These features are not present in the vicinity of the emplacement drifts. 
Therefore, the direction of water movement will be primarily controlled by the gravitational 
driving force, i.e. the flow will be predominantly vertical. This assumption is reasonable and 
does not require further verification. 
Assumption 4 (Section 6.4.1) 
Surface irregularities on the order of 10 cm developing over the course of 10,000 years will have 
a negligible effect on surface infiltration and therefore on potential repository performance. 
Basis: Surface irregularities on the order of 10 cm exist for the present-day topographical 
conditions on the surface of Yucca Mountain. These irregularities are not specifically modeled 
in the surface infiltration model. Therefore, changes to the surface of this magnitude are not

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significant and changes of this magnitude to the surface topography are negligible. This 
assumption is reasonable and does not require further verification. 
Assumption 5 (Section 6.5.1) 
The effects of human activities on climate over the 10,000 year performance period are bounded 
by the changes in climate resulting from natural phenomena. 
Basis: The effects of human activities on climate remain uncertain. However, repository 
performance is expected to be less favorable under the wetter, colder glacial climate. By 
stipulating an earlier start for the wetter and colder glacial climate (early in the 10,000 year 
regulatory period) , the potential effects of human activities are considered to be bounded. This 
assumption is reasonable and does not require further verification. 
Assumption 6 (Section 6.6.1 and 6.6.3) 
A build-up of gas pressure or trapping of intrusive gases in the repository environment will not 
occur over the 10,000-year performance period. 
Basis: The host rock environment at Yucca Mountain is an unsaturated and fractured rock. The 
fractures are known to be highly permeable to the gas phase. Fracture are expected to remain 
permeable, even where thermo-chemical alteration occurs (CRWMS M&O 2000s; Section 6). 
Therefore, there is no plausible mechanism by which there could be a build-up of gas pressure or 
trapping and concentration of intrusive gases. This assumption is reasonable and does not require 
further verification. 
Assumption 7 (Section 6.7.5) 
Silicic magmatism is not expected at Yucca Mountain over the 10,000 year performance period. 
Basis: Yucca Mountain lies outside the Timber Mountain caldera, the only source of silicic 
magmatism in the vicinity of Yucca Mountain over the last 11 million years (CRWMS M&O 
1998a, Figure 3.5-2 and Table 3.2-3). This assumption is reasonable and does not require further 
verification. 
Assumption 8 (Section 6.7.6) 
The large hydraulic gradient is a result of durable differences of lithology, alteration history, and 
structural deformation rather than transient stress effects. 
Basis: Observations of the geomechanical stress in the vicinity of Yucca Mountain (Stock and 
Healy 1988) do not support the hypothesis that the large hydraulic gradient results from a 
particular variation in stress conditions. Therefore, the cause of the large hydraulic gradient is 
likely to be a result of other factors such as lithology, alteration history, and structural 
deformation. This assumption is reasonable and does not require further verification.

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Assumption 9 (Section 6.7.9) 
A sudden release of all water and the associated radionuclides from the fracture domain of the 
perched water is a bounding scenario for the effects of perched water below the potential 
repository on performance. 
Basis: The only water in the perched zone available for sudden release is the water residing in 
the fracture domain. The release of radionuclides from the matrix of the perched water would 
occur much more slowly. Therefore, any effects of perched water drainage below the repository 
would be bounded by this scenario. This assumption is reasonable and does not require further 
verification. 
Assumption 10 (Section 6.3.8, 6.8.6) 
Changes in aqueous geochemistry in the repository environment are dominated by thermalchemical 
interactions associated with the potential repository. 
Basis: With the exception of climate change, the potential repository is the only perturbation that 
will potentially affect the aqueous geochemistry of the unsaturated zone over the 10,000 year 
regulatory period. The assumption that the effects of climate change on the geochemistry will be 
smaller than the effects of the potential repository is based on the fact that temperature changes 
driven by the repository will be much larger than temperature changes that occur as a result of 
climate change. Also, the repository introduces a large number of new materials (some that are 
in substantial quantities) that will influence the geochemistry. Climate change may influence the 
concentrations of dissolved salts in water that percolates, but will not introduce new materials 
This assumption requires further verification and therefore is TBV. 
Assumption 11 (Section 6.8.7, 6.8.8, and 6.8.10, 6.8.17, 6.8.18) 
Results from the near-field, thermal-hydrologic-chemical coupled processes model can be used 
to bound the effects of similar coupled processes on far-field flow and radionuclide transport. 
Basis: The effects of coupled processes in the near-field are expected to be more severe than in 
the far-field. This is due to the higher temperatures that will occur near the waste emplacement 
drifts, including boiling of the rock-water and the associated precipitation of minerals and 
condensation of dilute water. This assumption requires further verification and therefore is TBV. 
Assumption 12 (Section 6.8.12) 
The quantities of organic matter and microbes either emplaced or generated (through microbial 
growth processes) in the waste emplacement drifts are sufficiently small that they are unlikely to 
be of significance. 
Basis: This assumption is based on the limited use of organic matter in the emplacement drifts, 
the limited quantities of natural organic matter available in the unsaturated zone, and the 
resulting limitation on organic material needed for microbial growth. This assumption requires 
further verification and therefore is TBV.

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Assumption 13 (Sections 6.3.5, 6.8.4, 6.8.5) 
Thermal-hydrologic flow processes will have a minimal effect on radionuclide transport. 
Basis: The major effects of thermal-hydrologic flow processes will be near the emplacement 
drifts in the early part of the post-closure time period. Radionuclide releases will likely be after 
the main portion of the thermal pulse (after waste heat begins to dissipate) and a large part of the 
radionuclide transport process in the unsaturated zone will take place at locations outside the 
envelope of the main thermal-hydrologic effects. Thermo-hydrologic effects on the flow beneath 
the repository have been found to be small (CRWMS M&O 2000bb, Section 7). Therefore, the 
effects of thermal-hydrologic flow processes on radionuclide transport are expected to be 
negligible. These qualitative arguments require quantitative verification, therefore, this 
assumption is TBV. 
Assumption 14 (Section 6.8.14) 
Thermo-mechanical effects on hydrogeologic properties near waste emplacement drifts will be 
limited to a time period before any significant seepage into the drifts. 
Basis: The main compressive stresses caused by thermo-mechanical effects will occur during the 
period when temperatures are increasing. Drift seepage is not expected during this time period 
when temperatures are increasing because water is boiled and removed as vapor flow from the 
vicinity of the waste emplacement drifts. The effects of thermo-mechanical stress around the 
waste emplacement drifts are expected to be small by the time water is present to seep into the 
drifts. This assumption requires further verification and therefore is TBV. 
Assumption 15 (Section 6.7.1) 
Mechanical stress around waste emplacement drifts after the thermal period are dominated by the 
existing in-situ stress created by the presence of the opening. Therefore, changes to mechanical 
stress due to fault movement around waste emplacement drifts is negligible. 
Basis: Drift stability analyses have found that seismic activity has only a minor influence on 
rockfall in drifts (CRWMS M&O 2000d; Section 7). Therefore, the effects of fault movements 
on stress around the emplacement drifts are expected to be minor. This assumption requires 
further verification and therefore is TBV.

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6. ANALYSIS/MODEL 
There are 538 FEPs identified for unsaturated zone flow and transport from the Yucca Mountain 
Project (YMP) FEP database (CRWMS M&O 1999c). There is a large degree of overlap 
between these FEPs, and this overlap has been used to group FEPs into two broad categories, 
primary and secondary FEPs. Primary FEPs are those that capture the issues associated with 
secondary FEPs. In other words, the secondary FEPs are a subset of the primary FEPs. 
There are 85 FEPs identified in the YMP FEPs data base (Freeze 1999) as primary FEPs for 
unsaturated zone flow and transport. Of these, four primary FEPs and their related secondary 
FEPs have been transferred to different FEPs analysis documents. YMP primary FEP 
1.2.04.05.00, Magmatic Transport of Waste, plus 3 secondary FEPs are being treated in the 
Disruptive Events FEPs analysis. YMP FEPs 2.3.02.01.00, Soil Type, plus four secondary FEPs 
and 2.3.02.02.00, Radionuclide Accumulation in Soils, plus nine secondary FEPs, are being 
treated in the Biosphere FEPs analysis. Finally, YMP FEP 2.3.11.04.00, Groundwater Discharge 
to Surface, plus three secondary FEPs are being treated in the SZ FEPs analysis (CRWMS M&O 
2000z; Section 6). Therefore, 81 primary FEPs are considered here. 
The 81 primary FEPs considered in this analysis include an additional 434 secondary FEPs. 
The FEP disposition and screening arguments address both the primary and secondary FEPs. 
The FEPs are further divided into two broad categories: included and excluded FEPs. Included 
FEPs are those directly represented in TSPA models and process-level models that support 
TSPA. Included FEPs will be identified and briefly discussed, but the main description of theses 
FEPs are given in the reports describing the models used for or supporting TSPA. References to 
the appropriate reports will be given for these FEPs. Excluded FEPs are those not modeled in 
TSPA due to low probability or low consequence, as outlined in Section 4.2. In particular, low 
probability means that the occurrence of a FEP has a lower probability than 10-4 in 104 years. 
Clearly, probability arguments could only potentially apply to FEPs that are low probability 
events and not to FEPs that represent existing site features or processes. Low consequence 
arguments in this analysis are based on the UZ subsystem performance. Thus, if a FEP can be 
shown to have minimal consequence on UZ subsystem performance, then it will also have a 
minimal consequence on total system performance. UZ subsystem performance is defined by the 
release of radionuclides at the water table. In some cases, the disposition of the FEP is split, i.e. 
some aspects are included and some aspects are excluded from TSPA. The rationale for 
exclusion of a FEP is given in the screening argument presented for each excluded (or partially 
excluded) FEP. 
6.1 INCLUDED FEPS 
Table 2 gives the FEP numbers for the YMP primary FEPs, the primary FEP titles, and some, but 
not all, of the secondary FEP titles for this category. Not all the secondary FEP titles are listed 
because many are identical, or nearly identical to the primary FEP title or to other secondary FEP 
titles under the same primary FEP. A listing of the description of each of the primary and 
secondary FEPs in this category is given in Attachment I. Some aspects of certain FEPs in some 
of the subsequent sections of this documents are also included, but these FEPs with mixed 
character (partially exclude/partially include) are treated in Sections 6.2 through 6.8.

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Table 2. Included FEPS 
YMP Primary FEP Number Primary FEP Title Secondary FEPs Titles 
1.3.01.00.00 Climate change, global  No ice age 
 Solar insolation 
 Exit from glacial/interglacial 
cycling 
 Intensification of natural 
climate change 
 Present-day climatic conditions 
 Seasonality of climate 
 Future climate conditions 
 Warmer climate  arid 
 Warmer climate  seasonal 
humid 
 Warmer climate  equable 
humid 
 Seasons 
 Temperature 
1.3.07.02.00 Water table rise None 
2.1.08.01.00 Increased unsaturated water flux at 
the repository 
 Water container is thermally 
quenched by rapid influx of 
water 
2.1.08.02.00 Enhanced influx (Philip's drip) None 
2.2.03.01.00 Stratigraphy  Mesozoic sedimentary cover 
 Permo-carboniferous trough 
 Brine reservoirs 
2.2.03.02.00 Rock properties of host rock and 
other units 
 Rock heterogeneity (host rock) 
 Low permeability domain 
effective hydraulic properties 
 Major water-conducting faults 
effective hydraulic properties 
 Properties of far-field rock 
2.2.07.01.00 Locally saturated flow at 
bedrock/alluvium contact 
None 
2.2.07.02.00 Unsaturated groundwater flow in 
geosphere 
 Unsaturated rock 
 Soil depth 
2.2.07.03.00 Capillary rise None 
2.2.07.04.00 Focusing of unsaturated flow 
(fingers, weeps) 
 Effects of preferential flow 
paths 
 Seeps and weeps form as a 
locally saturated flow system 
 Fault control of fluid entrance 
to and movement away from 
the repository 
 Fingering  contaminant 
transport in fingers in the 
unsaturated zone 
2.2.07.08.00 Fracture flow in the unsaturated 
zone 
 Extreme channel flow of 
oxidants and nuclides (in 
geosphere)

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Table 2. Included FEPS (continued) 
YMP Primary FEP Number Primary FEP Title Secondary FEPs Titles 
2.2.07.09.00 Matrix imbibition in the unsaturated 
zone 
 Resaturation due to matrix 
imbibition of episodic fracture 
flow 
2.2.08.04.00 Redissolution of precipitates directs 
more corrosive fluids to containers 
None 
2.2.08.08.00 Matrix diffusion in geosphere None 
2.2.08.09.00 Sorption in UZ and SZ  Far-field transport: sorption 
including ion exchange 
 Far-field transport: changes in 
sorptive surfaces 
 Anion exchange, general (in 
geosphere) 
 Soil pore water pH 
 Sorption (reversible and 
irreversible) 
 Sorption (nonlinear) 
 Saturation (of sorption sites) 
 Kinetics of sorption 
 Changes in sorptive surfaces 
2.2.08.10.00 Colloidal transport in geosphere  Far-field transport: transport of 
radionuclides bound to 
microbes 
 Colloid transport occurs in a 
carrier plume (in geosphere) 
2.2.10.03.00 Natural geothermal effects  Geothermal regime 
 Geothermal gradient effects 
2.2.10.10.00 Two-phase buoyant flow / heat 
pipes 
None 
2.3.01.00.00 Topography and morphology  Topography (current) 
 Topography (future) 
2.3.11.01.00 Precipitation  Precipitation, temperature and 
soil water balance 
 Flood (meteorology) 
 Extremes of precipitation, snow 
melt and associated flooding 
(meteorology) 
2.3.11.02.00 Surface runoff and flooding  Runoff (near-surface 
hydrology) 
 Flooding (near-surface 
hydrology) 
 Evapotranspiration (nearsurface 
hydrology) 
 Flooding occurs in Drill Hole 
Wash and increases percolation 
below the wash 
 Faulting at surface produces a 
scarp causing an impoundment 
 River flooding 
3.1.01.01.00 Radioactive decay and ingrowth None

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6.1.1 Climate Change, Global (1.3.01.00.00) 
YMP Primary FEP Description: Climate change may affect the long-term performance of the 
repository. This includes the effects of long-term change in global climate (e.g., 
glacial/interglacial cycles) and shorter-term change in regional and local climate. Climate is 
typically characterized by temporal variations in precipitation and temperature. 
Disposition: Include 
Screening Argument: Global climate change is addressed in TSPA using a climate model based 
on paleoclimate information. That is, the record of climate changes in the past is used to predict 
the expected changes in climate for the future. The effects of seasonality is included in the 
climate model through the use of climate analogs with specific seasonal meteorological records. 
More specific information about the methods used to predict future climate change and the 
findings for the climate model are given in CRWMS M&O (2000a; Section 6). Climate 
modeling is incorporated into TSPA through the unsaturated zone flow fields that have different 
surface water infiltration as a result of different climates. A description of the modeling methods 
used for infiltration and how infiltration is affected by climate is given in CRWMS M&O 
(2000b; Section 6). The unsaturated zone flow model, which uses the infiltration results as upper 
boundary conditions for unsaturated zone flow calculations, is described in CRWMS M&O 
(2000c; Section 6). The incorporation of unsaturated zone flow fields into the TSPA are 
described in CRWMS M&O (2000w; Section 6). The secondary FEPs for climate change are 
included in the paleoclimate modeling method. Glaciation is brought up as an issue in some the 
secondary FEPs, which is also indirectly addressed by the paleoclimate model. Although glacial 
climates may occur over the next 10,000 years, glaciers are not expected to occur at Yucca 
Mountain over this time frame (USGS 2000a; Section 6). Therefore, glaciers are not part of the 
expected future climate conditions. Further discussion of glaciers are discussed in Sections 6.3.1 
and 6.3.2. A similar argument is applicable to the question of warmer humid climates, which are 
also not found in the paleoclimate record for this location. The potential effects of human 
activity on climate are discussed in Sections 6.5.1 through 6.5.4. 
6.1.2 Water Table Rise (1.3.07.02.00) 
YMP Primary FEP Description: Climate change could produce increased infiltration, 
leading to a rise in the regional water table, possibly affecting the release and exposure pathways 
from the repository. A regionally higher water table and change in flow patterns might move 
discharge points closer to the repository, or flood the repository. 
Disposition: Include 
Screening Argument: The potential for water table rise due to climate change is included in 
TSPA calculations using a water table rise model based on paleoclimate data. The paleoclimate 
data suggests that the historical water table has not risen to the level of the potential repository 
(Forester et al. 1999; pages 46, 56). Water table changes are implemented in the TSPA by 
allowing the water table to change elevation instantaneously upon change in climate. Other 
aspects of this FEP (change in SZ flow patterns and SZ discharge points) are addressed in 
CRWMS M&O (2000z; Section 6).

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6.1.3 Increased Unsaturated Water Flux at the Repository (2.1.08.01.00) 
YMP Primary FEP Description: An increase in the unsaturated water flux at the repository 
affects thermal, hydrologic, chemical, and mechanical behavior of the system. Extremely rapid 
influx could reduce temperatures below the boiling point during part or all of the thermal period. 
Increases in flux could result from climate change, but the cause of the increase is not an 
essential part of the FEP. 
Disposition: Include 
Screening Argument: As discussed in Section 6.1.1, climate change is included in the TSPA 
through the infiltration boundary condition for the unsaturated zone flow model. Therefore 
changes in unsaturated zone flow in response to climate change are included. The effects of 
changes in unsaturated zone flow due to climate change are also included in the calculations for 
the thermal-hydrologic behavior of the potential repository system (CRWMS M&O 2000f; 
Section 6). The effects of transient flow driven by thermo-hydrologic processes are also 
included in TSPA calculations for drift seepage (CRWMS M&O 2000o; Section 6). 
6.1.4 Enhanced Influx (Philip's drip) (2.1.08.02.00) 
YMP Primary FEP Description: An opening in unsaturated rock alters the hydraulic 
potential, affecting local saturation around the opening and redirecting flow. Some of the flow is 
directed to the opening where it is available to seep into the opening. 
Disposition: Include 
Screening Argument: This FEP refers to the effects of a circular opening, such as a drift, on 
unsaturated flow in the vicinity of the drift and drift seepage for a homogeneous rock 
environment (Philip et al., 1989). These effects are directly included in the drift seepage model, 
which goes beyond homogeneous rock conditions to include the important effects of rock 
heterogeneity on seepage into waste emplacement drifts (CRWMS M&O 2000g; Section 6). 
6.1.5 Stratigraphy (2.2.03.01.00) 
YMP Primary FEP Description: Stratigraphic information is necessary information for the 
performance assessment. This information should include identification of the relevant rock 
units, soils and alluvium, and their thicknesses, lateral extents, and relationships to each other. 
Major discontinuities should be identified. 
Disposition: Include 
Screening Argument: This FEP is included in the unsaturated zone flow model through 
hydrogeologic property sets for flow, sorption data for radionuclide transport, and pore size 
characteristics affecting colloid transport. Aspects that affect hydrogeologic properties for flow 
are discussed in CRWMS M&O (2000h; Section 6 and 2000i; Section 6). Aspects that affect 
aqueous radionuclide transport properties are addressed in CRWMS M&O (2000j; Section 6). 
Aspects that affect colloid transport are addressed in CRWMS M&O (2000k; Section 6). 
Secondary FEPs concerning Mesozoic sedimentary cover and the Permo-Carboniferous Trough 
are specific issues related to the NAGRA (Swiss Nuclear Waste Disposal Agency) Kristalin-I 
site and are not applicable to Yucca Mountain. Similarly, the secondary FEP addressing brine

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ANL-NBS-MD-000001 REV 00 24 of 77 March 2000 
reservoirs is a stratigraphic component important to the Waste Isolation Pilot Project (WIPP) 
project geology that is not applicable to Yucca Mountain. 
6.1.6 Rock Properties of Host Rock and Other Units (2.2.03.02.00) 
YMP Primary FEP Description: Physical properties such as porosity and permeability of the 
relevant rock units, soils, and alluvium are necessary for the performance assessment. Possible 
heterogeneities in these properties should be considered. 
Disposition: Include 
Screening Argument: This FEP is similar to the previous FEP on stratigraphy (Section 6.1.5) 
and the response in terms of treatment in TSPA is covered by that discussion. The question of 
rock heterogeneity is raised. The level of resolution for rock heterogeneity included in the 
models is based on the scale of the problem being addressed. For the unsaturated flow model, 
heterogeneity is modeled in terms of the sequence of hydrogeologic units and discrete faults 
(CRWMS M&O 2000c; Section 6 and CRWMS M&O 2000w; Section 6). For drift seepage a 
finer scale of resolution is needed and heterogeneity within the host rock unit is considered at the 
0.5 m scale (CRWMS M&O 2000g; Section 6). 
6.1.7 Locally Saturated Flow at Bedrock/Alluvium Contact (2.2.07.01.00) 
YMP Primary FEP Description: In washes in arid areas, infiltration can descend to the 
alluvium/bedrock interface and then proceed down the wash at that interface as a saturated flow 
system distant from the surface and distinct from the local water table. 
Disposition: Include 
Screening Argument: The phenomenon of infiltration resulting in a saturated condition at the 
bedrock/alluvium contact, with subsequent lateral drainage of this water, is included in the 
infiltration model. The details concerning of how this is captured in the infiltration model is 
given in CRWMS M&O (2000b; Section 6). 
6.1.8 Unsaturated Groundwater Flow in Geosphere (2.2.07.02.00) 
YMP Primary FEP Description: Groundwater flow occurs in unsaturated rocks in most 
locations above the water table at Yucca Mountain, including at the location of the repository. 
See other FEPs for discussions of specific issues related to unsaturated flow. See FEPs 
2.2.07.03.00 (capillary rise), 2.2.07.04.00 (focussing of unsaturated flow), 2.2.07.05.00 (effects 
of episodic infiltration), 2.2.07.07 (perched water), 2.2.07.08.00 (fracture flow), 2.2.07.09.00 
(matrix imbibition), 2.2.07.10.00 (condensation zone forms), 2.2.07.11.00 (return flow from 
condensation zone), and 2.2.10.10.00 (buoyant flow / heat pipes). 
Disposition: Include 
Screening Argument: This FEP is included in the unsaturated zone process model for 
mountain-scale flow (CRWMS M&O 2000c; Section 6, CRWMS M&O 2000l; Section 6, and 
CRWMS M&O 2000w; Section 6) and for drift seepage (CRWMS M&O 2000g; Section 6 and 
CRWMS M&O 2000o; Section 6). The flow model is for three-dimensional, steady flow in a 
heterogeneous dual-permeability system including discrete fault zones. The flow fields

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ANL-NBS-MD-000001 REV 00 25 of 77 March 2000 
generated by the process model are included directly in TSPA (for drift seepage and radionuclide 
transport) using a quasi-steady flow field approximation for climate change. The secondary FEP 
that addresses the potential for rock in the vicinity of the repository to become unsaturated is not 
relevant to Yucca Mountain because the potential repository is in the unsaturated zone. The 
effects of soil depth on unsaturated zone flow at Yucca Mountain are included in the infiltration 
model (CRWMS M&O 2000b; Section 6). 
6.1.9 Capillary Rise (2.2.07.03.00) 
YMP Primary FEP Description: Capillary rise involves the drawing up of water, above the 
water table or above locally saturated zones, in continuous pores of the unsaturated zone until the 
suction gradient is balanced by the gravitational pull downward. Capillary rise may provide a 
mechanism for radionuclides to reach the surface environment in locations where the water table 
is shallow. 
Disposition: Include 
Screening Argument: The effects of capillary forces on flow in the unsaturated zone are 
included directly in the process models for mountain-scale flow (CRWMS M&O 2000c; Section 
6 and CRWMS M&O 2000w; Section 6) and drift seepage (CRWMS M&O 2000g; Section 6 
and CRWMS M&O 2000o; Section 6). These effects include capillary rise. In the context of 
Yucca Mountain, this phenomenon refers to the fact that the zone of saturation will be slightly 
elevated above the level of zero capillary pressure. 
6.1.10 Focusing of Unsaturated Flow (Fingers, Weeps) (2.2.07.04.00) 
YMP Primary FEP Description: Unsaturated flow can differentiate into zones of greater and 
lower saturation (fingers) that may persist as preferential flow paths. Heterogeneities in rock 
properties, including fractures and faults, may contribute to focussing. Focussed flow may 
become locally saturated. 
Disposition: Include 
Screening Argument: The mountain-scale unsaturated zone flow model contains all the process 
mechanisms that could lead to flow focusing. However, the resolution of the mountain-scale 
model is limited to by the size of the girds. These grids are on the order of 100 m in horizontal 
dimension (CRWMS M&O 2000h; Section 6), therefore the ability to directly represent flow 
focusing in the process model is limited to the 100-meter scale or larger. The effects of 
averaging out smaller-scale flow variations is discussed in CRWMS M&O (2000l; Section 6). 
Faults are included in the unsaturated zone flow model as discrete features, therefore flow 
focusing in faults is included in the model (CRWMS M&O 2000c; Section 6 and CRWMS 
M&O 2000w; Section 6). The effects of the focused flow is included for radionuclide transport 
through the direct use of the process-model flow fields for calculating radionuclide transport in 
TSPA (CRWMS M&O 2000n; Section 6). 
The process-level drift seepage model also contains process mechanisms that could lead to flow 
focusing. In this case the grid resolution is much finer, with grid dimension of 0.5 m (CRWMS 
M&O 2000g; Section 6). The drift-scale model relies on an upper boundary condition 
established by the mountain-scale flow model and therefore is limited in its ability to model

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ANL-NBS-MD-000001 REV 00 26 of 77 March 2000 
focused flow. A drift seepage model abstraction is used in TSPA to compute seepage volumes 
based on the results of the process-level model. However, this model abstraction incorporates a 
calculation method to account for the effects of focused flow. See CRWMS M&O (2000o; 
Section 6) for further discussion of focused flow on drift seepage. 
6.1.11 Fracture Flow in the Unsaturated Zone (2.2.07.08.00) 
YMP Primary FEP Description: Fractures or other analogous channels act as conduits for 
fluids to move into the subsurface to interact with the repository and as conduits for fluids to 
leave the vicinity of the repository and be conducted to the SZ. 
Disposition: Include 
Screening Argument: This FEP is included in the process model for unsaturated zone flow at 
the mountain scale (CRWMS M&O 2000l; Section 6) and the drift scale (CRWMS M&O 2000g; 
Section 6). The conceptual model used is called the dual-permeability model in which the 
fractures and matrix are co-existing, interacting flow continua. The model allows for rapid flow 
and radionuclide transport through fractures with limited interaction with low-permeability 
matrix. See also section 6.1.8. 
6.1.12 Matrix Imbibition in the Unsaturated Zone (2.2.07.09.00) 
YMP Primary FEP Description: Water flowing in fractures or other channels in the 
unsaturated zone is imbibed into the surrounding rock matrix. This may occur during steady 
flow, episodic flow, or into matrix pores that have been dried out during the thermal period. 
Disposition: Include 
Screening Argument: Matrix imbibition is included in the process model for unsaturated zone 
flow at the mountain scale (CRWMS M&O 2000l; Section 6) and the drift scale (CRWMS M&O 
2000g; Section 6). Matrix imbibition refers to the movement of water into the matrix due to 
capillary forces. This process affects the distribution of flow between fractures and matrix in a 
dual-permeability flow model for fractured rock. The influence of matrix imbibition on episodic 
flow is discussed in Section 6.3.5. 
6.1.13 Redissolution of Precipitates Directs More Corrosive Fluids to Containers 
(2.2.08.04.00) 
YMP Primary FEP Description: Redissolution of precipitates which have plugged pores as a 
result of evaporation of ground water in the hot zone, produces a pulse of fluid reaching the 
waste containers when gravity-driven flow resumes, which is more corrosive than the original 
fluid in the rock. See also FEP 2.2.07.11.00 for a discussion of return flow from condensation 
cap. 
Disposition: Include 
Screening Argument: This FEP concerns the coupled effects of thermal-hydrologic-chemical 
processes on seepage water. These effects are included in the process model and abstraction for 
seepage water chemistry (CRWMS M&O 2000s; Section 6 and CRWMS M&O 2000x; Section 
6). The process model uses a two-dimensional drift-scale representation of the system that

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 27 of 77 March 2000 
incorporate the effects of reactive transport in a dual-permeability flow and transport 
formulation. The reactive transport aspect of the model includes the feedback of 
precipitation/dissolution processes on hydrogeologic properties. 
6.1.14 Matrix Diffusion in Geosphere (2.2.08.08.00) 
YMP Primary FEP Description: Matrix diffusion is the process by which radionuclides and 
other species transported by advective flow in fractures or other pathways move into the matrix 
of the porous rock by diffusion. Matrix diffusion can be a very efficient retarding mechanism, 
especially for strongly sorbed radionuclides due to the increase in rock surface accessible to 
sorption. 
Disposition: Include 
Screening Argument: Diffusion of radionuclides between the fracture and matrix continua is a 
process that is included in the unsaturated zone transport model (CRWMS M&O 2000q; Section 
6). The diffusion model used is based on a dual-porosity formulation in which the matrix water 
is stagnant. The abstraction for matrix diffusion includes the effects of partial saturation of the 
matrix, radionuclide sorption in the matrix, and finite spacing of fractures. 
6.1.15 Sorption in UZ and SZ (2.2.08.09.00) 
YMP Primary FEP Description: Sorption of dissolved and colloidal radionuclides can occur 
on the surfaces of both fractures and matrix in rock or soil along the transport path. Sorption may 
be reversible or irreversible, and it may occur as a linear or nonlinear process. Sorption kinetics 
and the availability of sites for sorption should be considered. 
Disposition: Include 
Screening Argument: Here we only comment on sorption in the unsaturated zone (UZ). 
Sorption is included in the TSPA model for unsaturated zone radionuclide transport as a linear 
equilibrium sorption (Kd) model (CRWMS M&O 2000q; Section 6). Sorption is only accounted 
for in the matrix continuum; there is no sorption modeled in the fracture continuum. Sorption 
characteristics of the rock minerals are assumed to be static in time. Distributions of sorption 
parameter values for each radionuclide/rock type combination (CRWMS M&O 2000j; Section 6) 
are sampled in the TSPA to account for the effects of natural variations in pore water chemistry 
and mineral surfaces on sorption. The effects of larger changes in geochemical conditions, due 
to repository perturbed conditions, are addressed in Sections 6.8.7, 6.8.8, 6.8.10, 6.8.11, and 
6.8.16 through 6.8.18. The effects of nonlinear sorption are conservatively bounded by the 
minimum Kd approach (CRWMS M&O 2000j; Section 6). The question of saturation of 
sorption sites is addressed in CRWMS M&O (2000j; Section 6). If sorption sites are near 
saturation, the relationship of sorbed concentration versus solution concentration is expected to 
be nonlinear. In some cases, nonlinear sorption is observed (CRWMS M&O 2000j; Section 6). 
However, the use of a linear sorption approximation is expected to be conservative over the 
range of measured solution concentrations for sorption. Anion exclusion is implicitly accounted 
for in the matrix diffusion coefficients, but not in advective transport calculations.

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ANL-NBS-MD-000001 REV 00 28 of 77 March 2000 
6.1.16 Colloidal Transport in Geosphere (2.2.08.10.00) 
YMP Primary FEP Description: Radionuclides may be transported in groundwater in the 
geosphere as colloidal species. Types of colloids include true colloids, pseudocolloids, and 
microbial colloids. 
Disposition: Include 
Screening Argument: Colloid transport is included in the TSPA model for unsaturated zone 
radionuclide transport. The process model for colloid transport is given in CRWMS M&O 
(2000k; Section 6). This model uses a two-dimensional discrete fracture model (DFM), in which 
the fracture and matrix are discretely represented. The effects of colloid filtration/resuspension 
are included as kinetic processes and colloid size exclusion from the matrix is also included in 
the process model. The abstraction of this process model in the particle tracking algorithm used 
for TSPA calculations is discussed in CRWMS M&O (2000q; Section 6). The abstraction is 
designed to work within the particle tracking algorithm used for solute transport. The model 
abstraction includes the filtration/resuspension process as an equilibrium process leading to an 
effective retardation for colloid movement. Radionuclide exchange between colloid and aqueous 
phases and size exclusion effects are also included in the colloid transport abstraction model. The 
potential effects of microbes on radionuclide transport, including colloidal transport, is addressed 
in Section 6.8.12 The potential effects of a carrier plume on radionuclide transport is addressed 
in Section 6.8.7. 
6.1.17 Natural Geothermal Effects (2.2.10.03.00) 
YMP Primary FEP Description: The existing geothermal gradient, and spatial or temporal 
variability in that gradient, may affect groundwater flow in the unsaturated and saturated zones. 
Disposition: Include 
Screening Argument: Natural geothermal effects are included in the models of thermohydrologic 
processes used to describe the effects of waste heat in the potential repository 
(CRWMS M&O 2000f; Section 6) The thermal-hydrologic models contain the natural 
geothermal gradient in its initialization. This gradient is specified by the ground surface 
temperature, the water table temperature, and the thermal conductivities from layer-to-layer. The 
results of these models are used in the TSPA through a model abstraction (CRWMS M&O 
2000r; Section 6). 
6.1.18 Two-Phase Buoyant Flow / Heat Pipes (2.2.10.10.00) 
YMP Primary FEP Description: Heat from waste generates two-phase buoyant flow. The 
vapor phase (water vapor) escapes from the mountain. A heat pipe consists a system for 
transferring energy between a hot and a cold region(source and sink respectively) using the heat 
of vaporization and movement of the vapor as the transfer mechanism. Two-phase circulation 
continues until the heat source is too weak to provide thermal gradients required to drive it. Any 
alteration of the rock adjacent to the drift produces may include dissolution which maintains the 
permeability necessary to support the circulation (as inferred for some geothermal systems). 
Disposition: Include

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ANL-NBS-MD-000001 REV 00 29 of 77 March 2000 
Screening Argument: The process mechanisms for heat pipe formation and evolution are 
included in the thermal-hydrologic process models used to describe the effects of waste heat in 
the potential repository system (CRWMS M&O 2000f; Section 6). The results of these models 
are used in the TSPA through a model abstraction (CRWMS M&O 2000r; Section 6). 
6.1.19 Topography and Morphology (2.3.01.00.00) 
YMP Primary FEP Description: This category includes FEPs related to the topography and 
surface morphology of the disposal region. Topographical features include outcrops and hills, 
water-filled depressions, wetlands, recharge areas and discharge areas. Topography, 
precipitation, and surficial permeability distribution in the system will determine the flow 
boundary conditions, i.e. location and amount of recharge and discharge in the system. 
Disposition: Include 
Screening Argument: Current topography is included in the infiltration model CRWMS M&O 
(2000b; Section 6). This is incorporated into the TSPA through the unsaturated zone flow fields 
that use the infiltration model results as upper boundary conditions (CRWMS M&O 2000c; 
Section 6 and CRWMS M&O 2000w; Section 6). Changes to the topography due to erosion or 
glaciation are addressed in Sections 6.4.1 and 6.3.2 respectively. 
6.1.20 Precipitation (2.3.11.01.00) 
YMP Primary FEP Description: Precipitation is an important control on the amount of 
recharge. It transports solutes with it as it flows downward through the subsurface or escapes as 
runoff. The amount of precipitation depends on climate. 
Disposition: Include 
Screening Argument: Precipitation is included in the infiltration model CRWMS M&O (2000b; 
Section 6). This is incorporated into the TSPA through the unsaturated zone flow fields that use 
the infiltration model results as upper boundary conditions (CRWMS M&O 2000c; Section 6 
and CRWMS M&O 2000w; Section 6). 
6.1.21 Surface Runoff and Flooding (2.3.11.02.00) 
YMP Primary FEP Description: Surface runoff and evapotranspiration are components in 
the water balance, together with precipitation and infiltration. They can also be important 
vehicles for the dispersion of contaminants. Surface runoff produces erosion, and can feed 
washes, arroyos, and impoundments, where flooding may lead to increased recharge. 
Disposition: Include 
Screening Argument: Surface runoff is included in the infiltration model CRWMS M&O 
(2000b; Section 6). This is incorporated into the TSPA through the unsaturated zone flow fields 
that use the infiltration model results as upper boundary conditions (CRWMS M&O 2000c; 
Section 6 and CRWMS M&O 2000w; Section 6). The effects of flooding over the locations of 
sealed boreholes is addressed in Section 6.2.1 The effects of faulting and creation of surface 
impoundments are addressed in Sections 6.7.2 and 6.7.7.

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ANL-NBS-MD-000001 REV 00 30 of 77 March 2000 
6.1.22 Radioactive Decay and Ingrowth (3.1.01.01.00) 
YMP Primary FEP Description: Radioactive decay of the fuel in the repository changes the 
radionuclide content in the fuel with time and generates heat. Radionuclide quantities in the 
system at any time are the result of the radioactive decay and the growth of daughter products as 
a consequence of that decay. The type of radiation generated by the decay depends on the 
radionuclide, and the penetrating distance of the radiation depends on the type of radiation, its 
energy and the surrounding medium. 
Disposition: Include 
Screening Argument: The effects of radioactive decay and ingrowth are included in the model 
for radionuclide transport in the unsaturated zone (CRWMS M&O 2000q; Section 6). Simple 
radioactive decay is computed using the process-level mathematical model. The chain-decay 
(ingrowth) algorithm is a based on a mathematical approximation that is shown to compare well 
with the process-level chain-decay mathematical model (CRWMS M&O 2000q; Section 6). 
6.2 BOREHOLES AND REPOSITORY SEALS 
This group of FEPs are generally excluded from the TSPA calculation, with some exceptions 
noted in the screening arguments presented here. These FEPs concern the effects of boreholes 
and repository drifts as pathways for fluid and radionuclide migration. The implicit assumption 
to be used in the TSPA is that boreholes are sealed so that the borehole region is 
indistinguishable from the natural rock in terms of fluid flow and radionuclide transport. 
Although boreholes will be sealed, the specific properties of the seals and their evolution over 
time are not accounted for in the flow and transport modeling. Similarly, repository drifts will be 
assumed to be sealed such that liquids or gases cannot migrate between emplacement drifts 
(other than through geosphere pathways). Arguments are presented here to demonstrate that the 
potential effects of leakage of the borehole or repository seals have a negligible effect on the 
potential performance of the repository. 
Table 3 gives the FEP numbers for the YMP primary FEPs, the primary FEP titles, and some, but 
not all, of the secondary FEP titles for this category. Not all the secondary FEP titles are listed 
because many are identical, or nearly identical to the primary FEP title or to other secondary FEP 
titles under the same primary FEP. A listing of the description of each of the primary and 
secondary FEPs in this category is given in Attachment II.

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Table 3. Included/Excluded FEPs: Repository and Borehole Seals 
YMP Primary FEP Number Primary FEP Title Secondary FEPs Titles 
1.1.01.01.00 Open site investigation boreholes  Exploratory boreholes (sealing) 
 Investigation boreholes 
 Underground boreholes 
1.1.01.02.00 Loss of integrity of borehole seals  Investigation borehole seal 
failure and degradation 
 Borehole seal failure 
1.1.02.01.00 Site flooding (during construction 
and operation) 
 Repository flooding during 
operation 
1.1.04.01.00 Incomplete closure  Non-sealed repository 
 Abandonment of unsealed 
repository 
 Unsealed boreholes and/or 
shafts 
1.1.11.00.00 Monitoring of repository  Monitoring and remedial 
activities 
 Post-closure monitoring 
1.4.04.02.00 Abandoned and undetected 
boreholes 
 Exploratory borehole creates 
flow pathway 
 Container lies in the trace of an 
old borehole 
 Waste-induced borehole flow 
(in waste and EBS) 
 Flow through undetected 
boreholes 
 Natural borehole fluid flow 
 Borehole induced 
mineralization 
 Borehole-induced geochemical 
changes 
2.1.05.01.00 Seal physical properties  Seal geometry 
 Consolidation of seals 
 Shaft and tunnel seals 
2.1.05.02.00 Groundwater flow and radionuclide 
transport in seals 
None 
2.1.05.03.00 Seal degradation  Seal evolution 
 Seal failure 
 Degradation of hole and shaft 
seals 
 Shaft or access tunnel seal 
failure and degradation 
 Degradation of hole and shaft 
seals 
 Loss of integrity of shaft or 
access tunnel seals 
 Mechanical degradation of seals 
 Chemical degradation of seals

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6.2.1 Open Site Investigation Boreholes (1.1.01.01.00) 
YMP Primary FEP Description: Site investigation boreholes that have been left open, 
improperly sealed, or reopened for some reason, could modify flow and transport properties and 
produce enhanced pathways between the surface and the repository. 
Disposition: Exclude effects of deep boreholes on the basis of low consequence. Include 
effects of ground-support boreholes on drift seepage. 
Screening Argument: Boreholes could act as enhanced pathways for the movement of water 
between the surface and the potential repository and the movement of radionuclides dissolved in 
water between the potential repository and the water table. The question to be addressed is 
whether or not the effects of such enhanced pathways could have a significant impact on 
repository performance. 
Table 4. Deep Boreholes in or Close to the Potential Repository Block 
Borehole 
Identifier 
Elevation (feet) Depth (feet) Easting (feet) Northing (feet) 
USW G-1 
(in block) 
4350.150 6000.00 561001.062 770501.625 
USW G-4 
(close to block) 
4166.130 3001.00 563081.750 765807.500 
USW H-3 
(close to block) 
4866.470 4000.00 558451.875 756542.000 
USW H-4 
(close to block) 
4096.170 4004.00 563911.375 761644.500 
USW H-5 
(in block) 
4851.350 4000.00 558908.438 766634.125 
USW NRG-6 
(close to block) 
4092.120 1100.00 564187.000 766726.500 
USW NRG-7a 
(close to block) 
4207.170 1513.00 562984.000 768880.125 
USW SD-12 
(in block) 
4342.820 2166.30 561605.625 761956.562 
USW SD-7 
(in block) 
4472.000 2675.10 561240.250 758949.875 
USW SD-9 
(in block) 
4272.640 2223.00 561818.000 767998.500 
USW UZ-1 
(in block) 
4424.730 1270.00 560221.562 771277.375 
USW UZ-14 
(in block) 
4425.400 2207.00 560141.562 771309.812 
USW UZ-6 
(in block) 
4925.170 1887.00 558325.000 759730.188 
USW UZ-6s 
(close to block) 
4949.160 519.00 558050.688 759909.312 
USW WT-2 
(close to block) 
4268.230 2060.00 561924.000 760661.562 
USW SD-6 
(in block) 
4905.400 2541.00 558652.625 762290.500 
DTN: MO9907YMP99025.001

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Only boreholes within or close to the potential repository block are important to the performance 
of the UZ. This is due to the predominantly vertical flow paths through the unsaturated zone. 
Boreholes that are laterally offset from the potential repository block will not influence water 
movement to the waste emplacement drifts or radionuclide transport from the waste 
emeplacement drifts to the water table. There are 10 deep boreholes in the potential repository 
block and 6 deep boreholes near the potential repository block (DTNs: MO9907YMP99025.001, 
SN9907T0872799.001) . There are an additional 18 shallow neutron boreholes in the potential 
repository block (not included in the Table 4). All but one of these 18 neutron boreholes have 
depths less than 100 feet. One neutron borehole (USW-UZ-N27) is about 202 feet deep (DTN: 
MO9907YMP99025.001), however this hole lies on the western boundary of the emplacement 
area. Any percolation coming through these pathways should be homogenized by matrix flow in 
the underlying Paintbrush nonwelded hydrogeologic unit. 
With regard to water movement between the surface and the potential repository, two important 
facts are relevant to the deep boreholes. First, most of these holes penetrate the unsaturated zone 
between the surface and the water table and second, none of the boreholes will intercept waste 
emplacement drifts. Therefore water entering these boreholes would tend to continue flowing 
through these holes to the water table (Assumption 1). A few of the deep boreholes are only 
partially penetrating. However, none of the (deep) boreholes in the potential repository block 
terminates above potential waste emplacement locations. Therefore, if these boreholes have any 
effect, they should act as conduits that conduct flow away from potential waste emplacement 
zones. 
The other aspect of this problem is the movement of dissolved radionuclides and radionuclides 
associated with mobile colloids between the potential repository and the water table. The 
movement of radionuclides could potentially be enhanced through the borehole pathways. 
However, unless there is significant lateral diversion of transport, radionuclides are unlikely to 
enter the borehole pathways because of the lateral offset between the boreholes and the waste 
emplacement locations. A potential worst case scenario is the migration of perched water 
through the borehole pathways. A bounding calculation was performed in which radionuclides 
in the perched water were immediately transported to the water table (see Section 6.7.9). This 
calculation shows that the perturbation in radionulcide mass flux at the water table due to a 
sudden release of radionuclides in the perched water zones is small. Therefore, the potential 
effects of these boreholes on repository performance, even if the borehole seals should fail 
completely, are expected to be negligible. 
Test boreholes drilled in the underground facility are all relatively short (they remain within the 
TSw hydrogeologic unit) and are only present in access and observation drifts, not in the waste 
emplacement drifts. Due to the highly fractured nature of the host rock, the presence of these 
short boreholes is expected to have negligible effects on radionuclide transport. A large number 
of boreholes are expected to be drilled in the waste emplacement drifts for installation of rock 
bolts for ground support. The effects of these boreholes are considered in the drift seepage 
process model (CRWMS M&O 2000g; Section 6). 
6.2.2 Loss Of Integrity Of Borehole Seals (1.1.01.02.00) 
YMP Primary FEP Description: Degradation and/or failure of seals in site investigation 
boreholes could alter the flow path between the surface and the repository and possibly create a 
short-circuit to the biosphere.

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ANL-NBS-MD-000001 REV 00 34 of 77 March 2000 
Disposition: Exclude effects of deep boreholes on the basis of low consequence. Include 
effects of ground-support boreholes on drift seepage. 
Screening Argument: This FEP is similar in content to the one discussed in Section 6.2.1. The 
effects of water movement between the surface and the potential repository, the movement of 
radionuclides between the potential repository and the water table, and the effects of short test 
boreholes drilled in the underground facility were found (see Section 6.2.1) to be negligible with 
respect to repository performance. Therefore, these aspects are excluded on the basis of low 
consequence. The effects of ground-support boreholes are considered in the drift seepage 
process model (CRWMS M&O 2000g; Section 6). 
6.2.3 Site Flooding (During Construction and Operation) (1.1.02.01.00) 
YMP Primary FEP Description: Flooding of the site during operations could introduce 
water into the underground, and could affect long-term performance. 
Disposition: Exclude on the basis of low probability. 
Screening Argument: This FEP describes an issue related to preclosure operations. The 
occurrence of a preclosure events will be addressed in operational plans approved by NRC. Any 
further deviation not addressed would be a noncompliance and require action based on NRC and 
EPA advice and consent. Therefore, this FEP is excluded from TSPA. 
6.2.4 Incomplete Closure (1.1.04.01.00) 
YMP Primary FEP Description: Disintegration of society could result in incomplete closure, 
sealing and decommissioning of the disposal vault. 
Disposition: Exclude effects of deep boreholes on the basis of low consequence. Include 
effects of ground-support boreholes on drift seepage. 
Screening Argument: This FEP is similar in content to the ones discussed in Sections 6.2.1 and 
6.2.7. The effects of water movement between the surface and the potential repository, the 
movement of radionuclides between the potential repository and the water table, and the effects 
of short test boreholes drilled in the underground facility were all found (see Section 6.2.1) to be 
negligible with respect to repository performance. The effects of drift seals on water or gas 
movement through the drifts were also assessed (Section 6.2.7) to have a negligible effect on 
repository performance. Therefore, these aspects are excluded on the basis of low consequence. 
The effects of ground-support boreholes are considered in the drift seepage process model 
(CRWMS M&O 2000g; Section 6). 
6.2.5 Monitoring of Repository (1.1.11.00.00) 
YMP Primary FEP Description: This category contains FEPs related to monitoring that is 
carried out during or after operations, for either operational safety or verification of long-term 
performance. Monitoring boreholes could provide enhanced pathways between the surface and 
the repository. 
Disposition: Exclude on the basis of low consequence.

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ANL-NBS-MD-000001 REV 00 35 of 77 March 2000 
Screening Argument: This FEP is similar to the ones discussed in Sections 6.2.1 and 6.2.7. 
Monitoring is a preclosure operational issue. The occurrence of a preclosure events will be 
addressed in operational plans approved by NRC. Any further deviation not addressed would be 
a noncompliance and require action based on NRC and EPA advice and consent. The effects of 
monitoring excavations, i.e., short boreholes in the vicinity of waste emplacement drifts, are 
excluded based on low consequence. Test boreholes drilled in the underground facility are all 
relatively short (they remain within the TSw hydrogeologic unit) and are only present in access 
and observation drifts, not in the waste emplacement drifts. Due to the highly fractured nature of 
the host rock, the presence of these short boreholes is expected to have negligible effects on 
postclosure repository behavior. 
6.2.6 Abandoned and Undetected Boreholes (1.4.04.02.00) 
YMP Primary FEP Description: Abandoned and undetected boreholes could provide 
pathways for preferential flow and, potentially, contaminant transport between any intersected 
zones. These flow connections could also result in geochemical changes in the receiving 
hydrologic units. 
Disposition: Exclude on the basis of low probability. 
Screening Argument: This FEP is similar to the one discussed in Section 6.2.1. As for the FEP 
in Section 6.2.1, we are only concerned with boreholes in or close to the potential repository 
block. However, the issue of abandoned, undetected boreholes is raised in this FEP. Boreholes 
drilled in the course of site-characterization activities are assumed to be identified. Boreholes 
drilled by others prior to the Yucca Mountain Site Characterization Project may exist. However, 
given the extensive site characterization carried out at Yucca Mountain for over 15 years (DOE 
1998; p. 1-1), the possibility of undetected boreholes at the site is very low (Assumption 2). 
6.2.7 Seal Physical Properties (2.1.05.01.00) 
YMP Primary FEP Description: Physical properties of the seals emplaced in the access 
ramps, ventilation shafts, and exploratory boreholes may affect the long-term performance of the 
disposal system. These properties include the location of the seals (and the openings they seal), 
and the physical and chemical characteristics of the sealing materials. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: The host rock in the potential repository is highly fractured; hence seals 
for repository access drifts are of little consequence for water movement in the repository 
environment. There is only a small driving force for water to move along the relatively 
horizontal access drifts or emplacement drifts. Water is expected to move in a vertical flow 
pattern through the waste emplacement drifts relative to the length scale of these drifts, with 
some flow diversion around the drifts due to the capillary barrier effect (Assumption 3). The 
ventilation shafts do connect to access drifts at the waste emplacement level, and therefore 
represent pathways for water to enter the waste emplacement drifts. For postclosure, the 
ventilation shafts will be backfilled. These ventilation shafts are expected to behave in a manner 
similar to smaller fault features with respect to flow from the surface to the potential repository. 
The shafts will be located such that they are not subject to flooding (CRWMS M&O 2000aa, 
Section 1.2.2.1.3). Therefore, the quantity of water available to flow through the ventilation

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ANL-NBS-MD-000001 REV 00 36 of 77 March 2000 
shafts is limited to rainfall and should not exceed infiltration that occurs in smaller fault features. 
Although fault features are suspected pathways for rapid migration of water from the surface to 
the potential repository (as observed from 36Cl measurements), the amount of water that can bypass 
matrix flow in the Paintbrush nonwelded hydrogeologic unit is a only a small fraction of 
the total infiltration (CRWMS M&O 1997, Section 6.12.4). Similarly, flow through the 
backfilled ventilation shafts should have a large component of matrix flow, greatly reducing the 
chance of transient water pulses penetrating from the surface to the waste emplacement drifts. 
Therefore, the effects of the ventilation shafts on flow from the surface to the potential repository 
is expected to be negligible. Gas flow could potentially move through the drifts, so drift seals 
could affect the nature of this flow. However, the fractured nature of the host rock ensures that 
gas will be able to move between drifts if there is a driving force for this flow pattern. Given 
these conditions, the effects of seals in the repository access drifts and ventilation shafts are 
expected to have very little effect on the movement of gas or water in the repository environment 
and therefore have little effect on repository performance. The effects of borehole seal failure 
properties can be excluded on the basis of low consequence, as discussed in Section 6.2.1. 
6.2.8 Groundwater Flow and Radionuclide Transport in Seals (2.1.05.02.00) 
YMP Primary FEP Description: Groundwater flow in through seals in the access ramps, 
ventilation shafts, and exploratory boreholes could affect long-term performance of the disposal 
system. Radionuclide transport through borehole seals below the repository should be 
considered. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: This FEP is similar in content to the ones discussed in Sections 6.2.1 and 
6.2.7. The effects of water movement between the surface and the potential repository, the 
movement of radionuclides between the potential repository and the water table, and the effects 
of short test boreholes drilled in the underground facility were all found (see Section 6.2.1) to be 
negligible with respect to repository performance. The effects of drift seals on water or gas 
movement through the drifts were also assessed (Section 6.2.7) to have a negligible effect on 
repository performance. Therefore, this FEP is excluded on the basis of low consequence. 
6.2.9 Seal Degradation (2.1.05.03.00) 
YMP Primary FEP Description: Degradation of seals in the access ramps, ventilation shafts, 
and exploratory boreholes could modify flow and transport properties, including enhanced flow 
and transport between the surface and the repository . Possible mechanisms for seal degradation 
include: chemical alteration from water interactions, wetting associated with condensation, and 
thermally -induced stress-strain changes. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: A detailed analysis of different seal failure mechanisms is irrelevant 
because the effects of borehole seal failure, discussed in Section 6.2.1, and drift seal failure, 
discussed in Section 6.2.7, are found to have negligible effects on repository performance. 
Borehole and drift seals are not relied upon for repository performance. Therefore, this FEP is 
excluded on the basis of low consequence.

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ANL-NBS-MD-000001 REV 00 37 of 77 March 2000 
6.3 EXTREME CLIMATE / EPISODIC TRANSIENT FLOW 
This group of FEPs are generally excluded from the TSPA calculation, although there are some 
exceptions as noted in the FEP screening arguments given below. These FEPs concern the 
effects of climate and episodic transient flow on hydrologic conditions, flow, and radionulcide 
transport in the unsaturated zone. In TSPA, episodic (or short duration) transient flows are 
ignored and an average steady flow is assumed to be representative. The rationale for this 
assumption is discussed below. Longer-term changes in climate are included in TSPA using a 
quasi-steady flow assumption, i.e. that the flow fields instantaneously adjust to steady conditions 
for a given climate (infiltration). However certain aspects of climate discussed in this section are 
excluded based on low probability. 
Table 5 gives the FEP numbers for the YMP primary FEPs, the primary FEP titles, and some, but 
not all, of the secondary FEP titles for this category. Not all the secondary FEP titles are listed 
because many are identical, or nearly identical to the primary FEP title or to other secondary FEP 
titles under the same primary FEP. A listing of the description of each of the primary and 
secondary FEPs in this category is given in Attachment III. 
Table 5. Included/Excluded FEPs: Climate and Episodic Transient Flow 
YMP Primary FEP Number Primary FEP Title Secondary FEPs Titles 
1.3.04.00.00 Periglacial effects  Permafrost 
 Accumulation of gasses under 
permafrost 
 Frost weathering 
 Solifluction 
 Tundra climate 
1.3.05.00.00 Glacial and ice sheet effects, local  Glacial erosion/sedimentation 
 Glacial-fluvial 
erosion/sedimentation 
 Ice sheet effects (loading, melt 
water recharge) 
 Isostatic rebound 
1.3.07.01.00 Drought / water table decline  Desert and unsaturation 
 Dust storms and desertification 
1.4.01.01.00 Climate modification increases 
recharge 
 Climate modification causes 
perched water to develop at 
base of Topopah Spring unit 
 Climate modification causes 
perched water to develop above 
repository 
 Climate modification raises 
water table 
 Climate modification raises 
water table to flood repository 
2.2.07.05.00 Flow and transport in the UZ from 
episodic infiltration 
 Episodic infiltration enhances 
colloid transport 
2.2.07.06.00 Episodic / pulse release from 
repository 
None 
2.2.07.07.00 Perched water develops None 
2.3.11.03.00 Infiltration and recharge (hydrologic 
and chemical effects) 
 Freshwater intrusion (in 
geosphere) 
 Equilibrated flow system 
 Draining flow system

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ANL-NBS-MD-000001 REV 00 38 of 77 March 2000 
 Surface water chemistry 
 Runoff is intercepted by wash 
terraces 
 Runoff to washes infiltrates and 
maintains a zone of higher flux 
to the unsaturated zone 
 Flow in ephemeral streams 
tends to be in channels and is a 
source of recharge 
 Changes in groundwater 
recharge and discharge 
 Coupling of surface water flow 
to climate/hydrologic modeling 
system 
6.3.1 Periglacial Effects (1.3.04.00.00) 
YMP Primary FEP Description: This category contains FEPs related to the physical 
processes and associated landforms in cold but ice-sheet-free environments. Permafrost and 
seasonal freeze/thaw cycles are characteristic of periglacial environments. 
Disposition: Exclude on the basis of low probability. 
Screening Argument: This FEP refers to climate conditions that could produce a cold, but 
glacier-free environment. Results of such a climate could include permafrost (permanently 
frozen ground). Some consequences of such a condition identified in the secondary FEPs are 
enhanced erosion due to the freeze/thaw cycle and the trapping of gases in or near the potential 
repository. Paleoclimate records indicate that such conditions are extremely unlikely to occur at 
Yucca Mountain over the next 10,000 years (USGS 2000a; Section 6). Therefore, this FEP is 
excluded from TSPA on the basis of low probability. 
6.3.2 Glacial and Ice Sheet Effects, Local (1.3.05.00.00) 
YMP Primary FEP Description: This category contains FEPs related to the effects of 
glaciers and ice sheets occurring within the region of the repository, including direct 
geomorphologic effects and hydrologic effects. These effects include changes in topography (due 
to glaciation and melt water), changes in flow fields, and isostatic depression and rebound. 
Disposition: Exclude on the basis of low probability. 
Screening Argument: This FEP refers to the effects of glaciers and ice sheets. Paleoclimate 
records indicate that such conditions are extremely unlikely to occur at Yucca Mountain over 
the next 10,000 years (USGS 2000a; Section 6). Therefore, this FEP is excluded from TSPA on 
the basis of low probability. 
6.3.3 Drought / Water Table Decline (1.3.07.01.00) 
YMP Primary FEP Description: Extreme climate change could produce an extended 
drought, leading to a decline in the water table in the saturated zone and affecting the release and 
exposure pathways from the repository.

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ANL-NBS-MD-000001 REV 00 39 of 77 March 2000 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: This FEP refers to the effects of a climate change that leads to much 
drier climate conditions. Some of the consequences of this type of climate change are water 
table decline and desertification of the surface environment. However, the Yucca Mountain 
region is already a desert environment, and future climates are only expected to have increased 
precipitation. In any case, a decline in the water table and lower infiltration rates would only 
enhance the unsaturated zone as a barrier to radionuclide movement. Therefore, it is 
conservative to exclude this FEP. 
6.3.4 Climate Modification Increases Recharge (1.4.01.01.00) 
YMP Primary FEP Description: Climate modification causes an increase in recharge in the 
Yucca Mountain region. Increased recharge might lead to increased flux through the repository, 
perched water, or water table rise. 
Disposition: Exclude effects of perched water below repository on the basis of low 
consequence. Include the effects of increased flux through repository and water table rise. 
Screening Argument: This FEP is related to the ones discussed in Sections 6.1.2 and 6.3.7. 
The potential for water table rise due to climate change is included in TSPA calculations using a 
water table rise model based on paleoclimate data. As discussed in Section 6.1.2, water table 
changes due to climate are not expected to reach the potential repository. Water table changes 
are implemented in the TSPA by allowing the water table to change elevation instantaneously 
upon change in climate. Another aspect of climate modification is the possibility of new perched 
water bodies forming either above or below the repository. The potential effect of perched water 
above the repository is the redirection of percolation flux for interaction with the repository. 
However, the current seepage abstraction contains a wide range of seepage due to encompass 
flow focusing and variability (CRWMS M&O 2000o; Section 6). Therefore, the effects of 
perched water are included indirectly in the seepage abstraction model. The effects of perched 
water below the repository are excluded on the basis of low consequence, as discussed in Section 
6.2.1. 
6.3.5 Flow and Transport in the UZ from Episodic Infiltration (2.2.07.05.00) 
YMP Primary FEP Description: Episodic flow occurs in the UZ as a result of episodic 
infiltration. See also FEP 2.2.07.02.00 (unsaturated groundwater flow), 2.3.11.03.00 
(infiltration), 2.2.07.04.00 (focusing of UZ flow), and 1.3.01.00.00 (climate change). Episodic 
flow may affect transport; for example, colloidal transport may be enhanced by episodic flow. 
Disposition: Exclude effects of episodic flow resulting from episodic infiltration on the basis 
of low consequence. Include the effects of transient flow due to thermal-hydrologic processes on 
drift seepage. Exclude the effects of transient flow due to thermal-hydrologic processes on 
radionuclide transport on the basis of low consequence. 
Screening Argument: The process that drives infiltration in the unsaturated zone is 
precipitation, which is clearly episodic in nature. Studies of episodic infiltration and percolation 
have found, however, that matrix-dominated flow in the PTn damps out the transient nature of 
the percolation such that unsaturated zone flow below the PTn is essentially steady (CRWMS

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ANL-NBS-MD-000001 REV 00 40 of 77 March 2000 
M&O 1998c, Section 2.4.2.8 ) Furthermore, the PTn is found over the entire repository block 
(see Attachment IX). This damping of transient flow is due to capillary forces and high matrix 
permeability in the PTn that lead to matrix imbibition of water from fractures the matrix. 
Therefore, this FEP is excluded on the basis that the unsaturated zone flow is steady at the 
repository and along radionuclide transport pathways. The effects of transient flow driven by 
thermo-hydrologic processes are included in TSPA calculations for drift seepage (CRWMS 
M&O 2000o; Section 6). The effects of such transient flow processes on mountain-scale flow 
and radionuclide transport is expected to be minimal (Assumption 13). Very small amounts of 
fracture flow do appear to penetrate as a transient through fault zones between the ground 
surface and the repository elevation as evidenced by high 36Cl concentrations in samples taken 
from the ESF. Higher concentrations of this isotope found in the ESF can only be explained 
through surface deposition of 36Cl from nuclear weapons testing and subsequent aqueous 
transport to certain ESF sampling locations in a period of approximately 50 years. However, the 
flow and transport models indicate that the quantity of water and dissolved constituents that do 
penetrate the PTn as a flow transient is negligible with respect to repository performance 
(CRWMS M&O 1998c, Section 2.4.2.8 ). 
6.3.6 Episodic / Pulse Release from Repository (2.2.07.06.00) 
YMP Primary FEP Description: Episodic release of radionuclides from the repository and 
radionuclide transport in the UZ may occur both because of episodic flow into the repository (see 
2.2.07.05.00, episodic flow in UZ), and because of other factors including intermittent failures of 
waste packages. 
Disposition: Exclude effects of episodic flow resulting from episodic infiltration on the basis 
of low consequence. Include the effects of transient flow due to thermal-hydrologic processes on 
drift seepage. Exclude the effects of transient flow due to thermal-hydrologic processes on 
radionuclide transport on the basis of low consequence. Include the effects of intermittent waste 
package failures. 
Screening Argument: This FEP refers to the effects of episodic flow and intermittent waste 
package failures to produce pulse releases of radionuclides from the repository. The effects of 
episodic flow at the mountain scale are excluded on the basis of low consequence, as discussed 
in Section 6.3.5. The effects of transient flow driven by thermo-hydrologic processes are 
included in TSPA calculations for drift seepage (CRWMS M&O 2000o; Section 6). The effects 
of intermittent waste package failures are included in the source term model for TSPA (CRWMS 
M&O 2000t; Section 6). 
6.3.7 Perched Water Develops (2.2.07.07.00) 
YMP Primary FEP Description: Zones of perched water may develop above the water table. 
If these zones occur above the repository, they may affect UZ flow between the surface and the 
waste packages. If they develop below the repository, for example at the base of the Topopah 
Spring welded unit, they may affect flow pathways and radionuclide transport between the waste 
packages and the saturated zone. 
Disposition: Exclude effects of perched water below repository on the basis of low 
consequence. Include the effects of increased flux through repository, water table rise and 
present-day perched water.

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ANL-NBS-MD-000001 REV 00 41 of 77 March 2000 
Screening Argument: The FEP refers to the possibility of new perched water bodies forming 
either above or below the repository under future climates. The potential effect of perched water 
above the repository is the redirection of percolation flux for interaction with the repository. 
However, the current seepage abstraction contains a wide range of seepage due to encompass 
flow focusing and variability (CRWMS M&O 2000o; Section 6). Therefore, the effects of 
perched water are included indirectly in the seepage abstraction model. The effects of existing 
perched water zones are included (CRWMS M&O 2000c; Section 6). The effects of changes to 
perched water below the repository are excluded on the basis of low consequence, as discussed 
in Section 6.2.1. 
6.3.8 Infiltration and Recharge (Hydrologic and Chemical Effects) (2.3.11.03.00) 
YMP Primary FEP Description: Infiltration into the subsurface provides a boundary 
condition for groundwater flow. The amount and location of the infiltration influences the 
hydraulic gradient and the height of the water table. Different sources of recharge water could 
change the chemistry of groundwaters passing through the repository. Mixing of these waters 
with other groundwaters could result in precipitation, dissolution and altered chemical gradients. 
Disposition: Exclude effects of changes to water chemistry on the basis of low consequence. 
Include the effects of changing infiltration and water table rise. 
Screening Argument: The hydrologic effects of infiltration and recharge are included in the 
infiltration model (CRWMS M&O 2000b; Section 6). This is incorporated into the TSPA 
through the unsaturated zone flow fields that use the infiltration model results as upper boundary 
conditions (CRWMS M&O 2000c; Section 6 and CRWMS M&O 2000w; Section 6). The 
effects of changes in infiltration water chemistry under different climates are assumed to be 
minimal (Assumption 10). Therefore, this aspect of the FEP is excluded from TSPA based on 
low consequence. 
6.4 EROSION/DISSOLUTON/SUBSIDENCE 
This group of FEPs are generally excluded from the TSPA calculation, although there are some 
exceptions as noted in the FEP screening arguments given below. These FEPs concern the 
effects of surface erosion, mineral dissolution, and subsidence on hydrologic conditions, flow, 
and radionuclide transport in the unsaturated zone. All of these processes are expected to occur 
at Yucca Mountain at low levels of activity. These FEPs are all excluded on the basis of low 
consequence given conservative bounds on the extent that these processes can affect the 
hydrogeologic system at Yucca Mountain in a 10,000-year period. 
Table 6 gives the FEP numbers for the YMP primary FEPs, the primary FEP titles, and some, but 
not all, of the secondary FEP titles for this category. Not all the secondary FEP titles are listed 
because many are identical, or nearly identical to the primary FEP title or to other secondary FEP 
titles under the same primary FEP. A listing of the description of each of the primary and 
secondary FEPs in this category is given in Attachment IV.

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ANL-NBS-MD-000001 REV 00 42 of 77 March 2000 
Table 6. Excluded FEPs: Erosion/Dissolution/Subsidence 
YMP Primary FEP Number Primary FEP Title Secondary FEPs Titles 
1.2.07.01.00 Erosion/denudation  Major incision 
 Generalized denudation 
 Localized denudation 
 Solid discharge via erosion 
process 
 Basement alteration 
 Hydraulic gradient changes 
(magnitude, direction) 
 Ephemeral stream erosion cuts 
Tiva Canyon units to 
underlying nonwelded units 
 Land slide 
 Chemical denudation and 
weathering 
 Fluvial erosion/sedimentation 
 Aeolian erosion 
 Mass wasting 
 Mechanical weathering 
1.2.07.02.00 Deposition  Aeolian deposition 
 Lacustrine deposition 
1.2.09.02.00 Large-scale dissolution  Shallow dissolution 
 Lateral dissolution 
 Solution chimneys 
 Breccia pipes 
 Collapse breccias 
2.2.06.04.00 Effects of subsidence  Large-scale rock fracturing 
 Borehole-induced solution and 
subsidence 
6.4.1 Erosion/Denudation (1.2.07.01.00) 
YMP Primary FEP Description: Erosion and denudation are processes which cause 
significant changes in the present-day topography and thus affect local and regional hydrology 
and the biosphere. Erosion of surficial materials can occur by a variety of means, including 
physical weathering (including glacial and fluvial erosion), chemical weathering, erosion by 
wind (aeolian erosion), and mass wasting (e.g., landslide) processes. The extent of erosion 
depends to a large extent on climate and uplift. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: Erosion is a process that is expected to be ongoing at Yucca Mountain 
over the 10,000-year performance period. The maximum erosion over a 10,000 year period is 
expected to be less than 10 cm (YMP 1993, p. 55), which is within the range of existing surface 
irregularities. Therefore, the effects of surface erosion are expected to be negligible 
(Assumption 4). The effects of radionuclides that may be present in surface soils or rock at the 
accessible environment, which subsequently enter the biosphere through erosion processes, are 
included (CRWMS M&O 2000u; Section 6).

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ANL-NBS-MD-000001 REV 00 43 of 77 March 2000 
6.4.2 Deposition (1.2.07.02.00) 
YMP Primary FEP Description: Deposition and erosion are processes which cause 
significant changes in the present-day topography and thus affect local and regional hydrology 
and the biosphere. Deposition of surficial materials can occur by a variety of means, including 
fluvial, aeolian, and lacustrine deposition and redistribution of soil through weathering and mass 
wasting processes. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: Like erosion, deposition is a process that is expected to be ongoing at 
Yucca Mountain over the 10,000-year performance period. However, given the topographic 
character of Yucca Mountain, erosion is expected to dominate over deposition. Deposition is 
believed to be a dominant process in Fortymile Wash (YMP 1993, p. 55). However, this 
drainage channel has no effect on unsaturated zone flow and transport at Yucca Mountain due to 
its lateral offset. Therefore deposition is excluded from TSPA on the basis of low consequence. 
6.4.3 Large-Scale Dissolution (1.2.09.02.00) 
YMP Primary FEP Description: Dissolution can occur when any soluble mineral is removed 
by flowing water, and large-scale dissolution is a potentially important process in rocks that are 
composed predominantly of water-soluble evaporite minerals, such as salt. 
Disposition: Exclude on the basis of low probability. 
Screening Argument: This FEP is principally concerned with the dissolution of highly soluble 
evaporite rocks such as halite or carbonates. Evaporitic minerals are present, but the unsaturated 
zone at Yucca Mountain is primarily composed of vitric high-silica rhyolite and quartz latite (or 
trachyte) (CRWMS M&O 1998a; Section 3.5.2.1, paragraph 7). Solubilities of these minerals 
are too low to produce large dissolution cavities. Local dissolution processes that affect, for 
example, fracture filling minerals are discussed in Section 6.8.8. 
6.4.4 Effects of Subsidence (2.2.06.04.00) 
YMP Primary FEP Description: Subsidence above the mined underground facility or other 
openings affects the properties of the overlying rocks and surface topography. Changes in rock 
properties, such as enhanced permeability, may alter flow paths from the surface to the 
repository. Changes in surface topography may alter run-off and infiltration, and may perhaps 
create impoundments. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: Subsidence can occur as a result of underground excavations. In coal 
mining, subsidence has been found to occur when more than 50% of the coal bed was removed 
(Keller 1992; p. 142). In the case of Yucca Mountain, the percent of removal of is very small. 
The emplacement drift diameter is less than 10% of the drift spacing (CRWMS M&O 2000aa; 
Section 1.2.1). Furthermore, drift collapse has been modeled for drift seepage considerations 
(CRWMS M&O 2000d; Section 6) and the collapse is found to only extend about 9 meters above 
the initial drift crown elevation. The effects of changes to fracture characteristics around 
emplacement drifts due to stress relief and drift collapse is discussed in Section 6.8.3. Therefore,

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ANL-NBS-MD-000001 REV 00 44 of 77 March 2000 
subsidence is expected to have a negligible impact on large-scale unsaturated zone flow or 
surface topography and is excluded from TSPA modeling. 
6.5 HUMAN INFLUENCES ON CLIMATE/SOIL 
This group of FEPs are excluded from the TSPA calculation. These FEPs concern the effects of 
human activity on regional and global climate, as well as local effects on soils. These FEPs are 
all excluded on the basis of conservative assumptions used in climate modeling and the ranges of 
parameters used to characterized unsaturated zone water chemistry. 
Table 7 gives the FEP numbers for the YMP primary FEPs, the primary FEP titles, and some, but 
not all, of the secondary FEP titles for this category. Not all the secondary FEP titles are listed 
because many are identical, or nearly identical to the primary FEP title or to other secondary FEP 
titles under the same primary FEP. A listing of the description of each of the primary and 
secondary FEPs in this category is given in Attachment V. 
Table 7. Excluded FEPs: Human Influences on Climate/Soil 
YMP Primary FEP Number Primary FEP Title Secondary FEPs Titles 
1.4.01.00.00 Human influences on climate None 
1.4.01.02.00 Greenhouse gas effects None 
1.4.01.03.00 Acid rain  Surface water pH 
1.4.01.04.00 Ozone layer failure None 
1.4.06.01.00 Altered soil or surface water 
chemistry 
 Groundwater pollution 
 Surface pollution (soils, rivers) 
 Altered soil or surface water 
chemistry by human activities 
 Far-field hydrochemistry  
acids, oxidants, nitrate 
 Arable farming 
6.5.1 Human Influences on Climate (1.4.01.00.00) 
YMP Primary FEP Description: This category contains FEPs related to future human 
actions that could influence global, regional, or local climate. Human actions may be intentional 
or accidental. This FEP aggregates all human influences on climate into a single category. 
Technical discussions are presented separately for increased recharge (1.4.01.01.00), greenhouse 
gas effects (1.4.01.02.00), acid rain (1.4.01.03.00), and ozone layer failure (1.4.01.04.00). 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: Human activities are suspected of having some effects on climate. In 
particular, global warming due to emission of greenhouse gases is one example of the potential 
consequences of human activity on global climate. However, human activities are not the only 
factor important to climate change. Major changes in climate are known to have occurred prior 
to any significant human activities (USGS 2000a; Section 6). By incorporating changes to 
wetter climates driven by glacial cycles during the 10,000-year performance period, the potential 
effects of human activities on climate are conservatively bounded (Assumption 5). Therefore, 
the effects of human activity on climate are excluded from TSPA.

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6.5.2 Greenhouse Gas Effects (1.4.01.02.00) 
YMP Primary FEP Description: The greenhouse effect refers to the presence of carbon 
dioxide and other gases in the atmosphere that tend to allow solar radiation through to the earth's 
surface and reflect heat back to it. Thus, these gases act much as the glass of a greenhouse, with 
the earth as the greenhouse. Human activities such as burning of fossil fuels, forest clearance, 
and industrial processes produce these greenhouse gases. The greenhouse effect could increase 
concentrations of carbon dioxide and other gases in the atmosphere, and lead to changes in 
climate such as global warming. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: This FEP is closely related to the one discussed in Section 6.5.1. Human 
activities are suspected of having some effects on climate. In particular, global warming due to 
emission of greenhouse gases is one example of the potential consequences of human activity on 
global climate. However, human activities are not the only factor important to climate change. 
Major changes in climate are known to have occurred prior to any significant human activities 
(USGS 2000a; Section 6). By incorporating changes to wetter climates driven by glacial cycles 
during the 10,000-year performance period, the potential effects of human activities on climate 
are conservatively bounded (Assumption 5). Therefore, the effects of human activity on climate 
are excluded from TSPA. 
6.5.3 Acid Rain (1.4.01.03.00) 
YMP Primary FEP Description: Human actions may result in acid rain on a local to regional 
scale. Acid rain can detrimentally affect aquatic and terrestrial life by interfering with the 
growth, reproduction and survival of organisms. It can influence the behavior and transport of 
contaminants in the biosphere, particularly by affecting surface water and soil chemistry. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: Acid rain is found to occur as a result of human activities, particularly 
combustion products containing sulfur and nitrogen oxides (Keller 1992; p. 432). However, 
Yucca Mountain lies in an area of relatively high calcic soils common to desert environments 
(Taylor 1986, p. 34). The carbonate content of soils and rock tend to buffer the effects of acidic 
rainwater (Keller 1992; pp. 432, 433). Furthermore, there are numerous other factors that are 
expected to have more effect on water chemistry than acid rain, including the thermal and 
materials interactions of the repository (see Sections 6.8.6, 6.8.7, 6.8.8, 6.8.16, 6.8.17, 6.8.18). 
Therefore, the effects of acid rain are excluded from TSPA. 
6.5.4 Ozone Layer Failure (1.4.01.04.00) 
YMP Primary FEP Description: Human actions (i.e., the use of certain industrial chemicals) 
may lead to destruction or damage to the earth's ozone layer. This may lead to significant 
changes to the climate, affecting properties of the geosphere such as groundwater flow patterns. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: This FEP is closely related to the one discussed in Section 6.5.1. Human 
activities are suspected of having some effects on climate. In particular, global warming due to

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emission of greenhouse gases is one example of the potential consequences of human activity on 
global climate. However, human activities are not the only factor important to climate change. 
Major changes in climate are known to have occurred prior to any significant human activities 
(USGS 2000a; Section 6). By incorporating changes to wetter climates driven by glacial cycles 
during the 10,000-year performance period, the potential effects of human activities on climate 
are conservatively bounded (Assumption 5). Therefore, the effects of human activity on climate 
are excluded from TSPA. 
6.5.5 Altered Soil or Surface Water Chemistry (1.4.06.01.00) 
YMP Primary FEP Description: Human activities (e.g., industrial pollution, agricultural 
chemicals) may produce local changes to the soil chemistry or to the chemistry of water 
infiltrating Yucca Mtn and could provide a plume of unspecified nature to interact with the 
repository and possibly with containers. 
Disposition: Exclude on the basis of low probability. 
Screening Argument: Human activities may affect soil and surface water chemistry due to 
agricultural activities or pollution from industrial activities. Current land use at Yucca Mountain 
does not include activities such as these that may lead to large-scale changes in soil or water 
chemistry and there is no basis to predict that such activity will occur in the future. Therefore, 
the effects of human activities on soil and water chemistry are excluded from TSPA. 
6.6 NATURAL GAS/GAS GENERATION EFFECTS 
This group of FEPs are excluded from the TSPA calculation. These FEPs concern the effects of 
gas generation due to chemical reactions in the repository, the intrusion of naturally occurring 
gases such as methane, and gas-phase radionuclide transport. These FEPs are all excluded on the 
basis of low consequence to performance. 
Table 8 gives the FEP numbers for the YMP primary FEPs, the primary FEP titles, and some, but 
not all, of the secondary FEP titles for this category. Not all the secondary FEP titles are listed 
because many are identical, or nearly identical to the primary FEP title or to other secondary FEP 
titles under the same primary FEP. A listing of the description of each of the primary and 
secondary FEPs in this category is given in Attachment VI.

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Table 8. Excluded FEPs: Natural Gas/Gas Generation Effects 
YMP Primary FEP Number Primary FEP Title Secondary FEPs Titles 
2.1.12.01.00 Gas generation  Formation of gases (in waste 
and engineered barrier system) 
 Gas generation, buffer/backfill 
 Chemotoxic gasses (in waste 
and engineered barrier system) 
 Pressurization (in waste and 
engineered barrier system) 
2.2.10.11.00 Natural air flow in unsaturated zone None 
2.2.11.01.00 Naturally-occurring gases in 
geosphere 
 Methane intrusion 
 Geogas 
 Gas generation and gas sources, 
far-field 
2.2.11.02.00 Gas pressure effects  Fluid flow due to gas 
pressurization (in waste and 
engineered barrier system) 
2.2.11.03.00 Gas transport in geosphere  Gases and gas transport 
 Far-field transport: gas induced 
groundwater transport 
 Gas-mediated transport 
 Far-field transport: transport of 
radioactive gases 
 Gas discharge 
6.6.1 Gas Generation (2.1.12.01.00) 
YMP Primary FEP Description: Gas may be generated in the repository by a variety of 
mechanisms. Gas generation might lead to pressurization of the repository, produce multiphase 
flow, and affect radionuclide transport. This FEP aggregates all types of gas generation into a 
single category. Technical discussions are presented separately for gas generation from fuel 
decay (FEP 2.1.12.02.00), corrosion (FEP 2.1.12.03.00), microbial degradation (FEP 
2.1.12.04.00), and radiolysis (FEP 2.1.13.01.00). 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: This FEP refers to the generation of gases in the repository as a result of 
thermal-chemical and radiolysis reactions. Some of the consequences include the production of 
corrosive or explosive gases such as hydrogen sulfide. The physical/chemical effects of gas 
generation, primarily the interplay of O2, CO2, and H2O (vapor), are addressed in CRWMS 
M&O (2000r; Section 6 and 2000y; Section 6). No corrosive or explosive gases have been 
identified (CRWMS M&O 2000y; Section 6). In the unsaturated zone of Yucca Mountain, the 
build-up of any significant gas pressure is unlikely due to the permeable fracture pathways 
(Assumption 6). Therefore, this aspect of the effect of gas generation is excluded from TSPA. 
6.6.2 Natural Air Flow in Unsaturated Zone (2.2.10.11.00) 
YMP Primary FEP Description: Natural convective air circulation has been observed at a 
borehole at the top of the mountain. Repository heat is expected to increase this flow.

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Disposition: Exclude on the basis of low consequence. 
Screening Argument: Natural air flow is expected to have a negligible impact on thermohydrologic 
processes due to the large volume of thermally-generated water-vapor flow. With 
respect to radionuclide transport, no radionuclides are transported in the gas phase; all 
radionuclides move in the aqueous phase. The effects of natural air flow have little consequence 
on water movement in the unsaturated zone because of the high mobility of the gas phase, hence 
little dynamic interaction between the phases. A standard approximation for unsaturated flow is 
to neglect the effects of the gas phase. 
6.6.3 Naturally-Occurring Gases in Geosphere (2.2.11.01.00) 
YMP Primary FEP Description: Naturally-occurring gases in the geosphere may intrude 
into the repository or may influence groundwater flow paths and releases to the biosphere. 
Potential sources for gas might be clathrates, microbial degradation of organic material or deep 
gases in general. 
Disposition: Exclude on the basis of low consequence and low probability. 
Screening Argument: This FEP refers to the possible occurrence of gases such as methane that 
could enter the repository or affect radionuclide pathways. However, no methane or other 
geogases have been detected in the site characterization activities at Yucca Mountain. Carbon 
dioxide is at elevated levels in the unsaturated zone compared with the atmosphere but this is 
believed to be generated in the soil horizon. Furthermore, with the repository in the unsaturated 
zone in a highly fractured rock, there is no mechanism for build-up of intrusive gases 
(Assumption 6). Therefore, this FEP is excluded from TSPA. 
6.6.4 Gas Pressure Effects (2.2.11.02.00) 
YMP Primary FEP Description: Pressure variations due to gas generation may affect flow 
patterns and contaminant transport in the geosphere. 
Disposition: Exclude on the basis of low consequence and low probability. 
Screening Argument: This FEP is very similar in nature to those discussed in Sections 6.6.1 
and 6.6.3. In the unsaturated zone of Yucca Mountain, the build-up of any significant gas 
pressure is unlikely due to the permeable fracture pathways (Assumption 6). Therefore, this 
aspect of the effect of gas generation is excluded from TSPA. 
6.6.5 Gas Transport in Geosphere (2.2.11.03.00) 
YMP Primary FEP Description: Gas released from the drifts and gas generated in the nearfield 
rock will flow through fracture systems in the near-field rock and in the geosphere. Certain 
gaseous or volatile radionuclides may be able to migrate through the far-field faster than the 
groundwater advection rate. Degassing could affect flow and transport of gaseous contaminants. 
Gases could also affect other contaminants if water flow is driven by large gas bubbles forming 
in the repository. 
Disposition: Exclude on the basis of low consequence and low probability.

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Screening Argument: This FEP refers to the release of gas-phase radionuclides through gas 
bubbles. Because the repository at Yucca Mountain would be located in the unsaturated zone, 
releases to the gas phase would be direct. Therefore, the bubble-release mechanism is not 
relevant and this FEP is excluded from TSPA. Releases of volatile radionuclides are excluded 
on the basis that all radionuclides in TSPA are released into the aqueous phase. This is expected 
to bound any dose effects of gas-phase releases due to the large dilution of gas-phase releases in 
the atmosphere. 
6.7 SEISMIC/IGNEOUS/ROCK CHARACTERISTICS 
This group of FEPs constitutes a mixture of items both included and excluded from the TSPA 
calculation. These FEPs concern the effects of rock characteristics, and geologic processes that 
can affect rock characteristics, such as seismic and igneous processes. Although all existing 
characteristics are included in TSPA, some of the processes that may influence these 
characteristics are excluded on the basis of low consequence. Other effects believed to be more 
important are included. 
Table 9 gives the FEP numbers for the YMP primary FEPs, the primary FEP titles, and some, but 
not all, of the secondary FEP titles for this category. Not all the secondary FEP titles are listed 
because many are identical, or nearly identical to the primary FEP title or to other secondary FEP 
titles under the same primary FEP. A listing of the description of each of the primary and 
secondary FEPs in this category is given in Attachment VII. 
Table 9. Included/Excluded FEPs: Seismic/Igneous/Rock Characteristics 
YMP Primary FEP Number Primary FEP Title Secondary FEPs Titles 
1.2.02.01.00 Fractures  Changes in fracture properties 
 Fracturing 
1.2.02.02.00 Faulting  Fault generation 
 Fault activation 
 Movements along small-scale 
faults 
 Formation of new faults 
 Fault movement 
 Normal faulting occurs or exists 
at Yucca Mountain 
 Strike-slip faulting occurs or 
exists at Yucca Mountain 
 Detachment faulting occurs or 
exists at Yucca Mountain 
 Dip-slip faulting occurs at 
Yucca Mountain 
 Old fault strand is reactivated at 
Yucca Mountain 
 New fault strand is reactivated 
at Yucca Mountain 
 Movements along major faults 
1.2.03.01.00 Seismic activity  Earthquakes 
 Seismicity 
 Seismic activity

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Table 9. Included/Excluded FEPs: Seismic/Igneous/Rock Characteristics (continued) 
YMP Primary FEP Number Primary FEP Title Secondary FEPs Titles 
1.2.04.02.00 Igneous activity causes changes to 
rock properties 
 Dike provides a permeable flow 
path 
 Dike provides a barrier to flow 
 Volcanic activity in the vicinity 
produces an impoundment 
 Igneous activity causes extreme 
changes to rock geochemical 
properties 
 Intrusion (magmatic) 
 Dike related fractures after flow 
 Magmatic activity 
1.2.06.00.00 Hydrothermal activity None 
1.2.10.01.00 Hydrological response to seismic 
activity 
 Fault movement pumps fluid 
from SZ to UZ (seismic 
pumping) 
 Fault creep causes short term 
fluctuations of the water table 
 New faulting breaches flow 
barrier controlling large 
hydraulic gradient to the north 
 Normal faulting produces a trap 
for laterally moving moisture in 
the Tiva Canyon unit 
 Head-driven flow up from 
carbonates 
 Fault pathway through the 
altered Topopah Spring basal 
vitrophyre 
 Fault movement connects tuff 
and carbonate aquifers 
 Fault establishes pathway 
through the UZ 
 Fluid supplied by a fault 
migrates down the drift 
 Fault intersects and drains 
condensate zone 
 Flow barrier south of site 
blocks flow, causing water 
table to rise 
1.2.10.02.00 Hydrologic response to igneous 
activity 
 Interaction of water table with 
magma 
 Interaction of unsaturated zone 
pore water with magma

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Table 9. Included/Excluded FEPs: Seismic/Igneous/Rock Characteristics (continued) 
YMP Primary FEP Number Primary FEP Title Secondary FEPs Titles 
2.2.06.02.00 Changes in stress (due to thermal, 
seismic, or tectonic effects) produce 
change in permeability of faults 
 Aseismic alteration of 
permeability along and across 
faults 
 Fracture dilation along faults 
creates zones of enhances 
permeability 
 Relaxation of thermal stresses 
by fault movement 
 Seismically-stimulated release 
of thermo-mechanical stress on 
bounding faults 
2.2.06.03.00 Changes in stress (due to seismic or 
tectonic effects) alter perched water 
zones 
 Perched zones develop as a 
result of stress changes 
2.2.12.00.00 Undetected features (in geosphere)  Undetected dike beneath the 
repository passing through the 
Calico Hills provides a highly 
permeable flow path 
 Undetected fault dips below the 
repository providing a highly 
permeable flow path 
 Undetected fault beneath the 
repository acts as a flow barrier 
altering the flow system 
 Perched water escapes detection 
and waste is put in it 
 Undiscovered mine shaft (an 
old prospect hole) in a wash 
acts as a source for increased 
local infiltration 
 Undetected fracture zone 
 Undetected past intrusions 
 Undetected discontinuities 
6.7.1 Fractures (1.2.02.01.00) 
YMP Primary FEP Description: Groundwater flow in the Yucca Mountain region and 
transport of any released radionuclides may take place along fractures. Transmissive fractures 
may be existing, reactivated, or newly formed fractures. The rate of flow and the extent of 
transport in fractures is influenced by characteristics such as orientation, aperture, asperity, 
fracture length, connectivity, and the nature of any linings or infills. Generation of new fractures 
and reactivation of preexisting fractures may significantly change the flow and transport paths. 
Newly formed and reactivated fractures typically result from thermal, seismic, or tectonic events. 
Disposition: Include effects of present-day fracture system. Exclude the effects of changes to 
the fracture system on the basis of low consequence. 
Screening Argument: This FEP concerns a characteristic feature of Yucca Mountain geology. 
The present-day fracture system is directly included in the flow and transport models of the 
unsaturated zone (CRWMS M&O 2000l; Section 6). The effects of changes to the fracture 
system due to geologic or geochemical effects on mountain-scale flow and radionuclide transport

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have been investigated using a sensitivity approach (CRWMS M&O 2000e; Section 6). The 
results indicate that radionuclide transport results are relatively insensitive to large variations in 
the fracture aperture. 
Fault displacements may change the mechanical stress in the vicinity of emplacement drifts, 
resulting in changes to fracture aperture. The effects of changes to the mechanical stress due to 
faults are expected to be small in comparison with the mechanical stresses due to the presence of 
the drift (Assumption 15). Therefore, changes to the fracture characteristics in the vicinity of 
waste emplacement drifts are excluded from TSPA on the basis of low consequence. 
6.7.2 Faulting (1.2.02.02.00) 
YMP Primary FEP Description: Faulting may occur due to sudden major changes in the 
stress situation (e.g. seismic activity) or due to slow motions in the rock mass (e.g., tectonic 
activity). Movement along existing fractures and faults is more likely than the formation of new 
faults. Faulting may alter the rock permeability in the rock mass and alter or short-circuit the 
flow paths and flow distributions close to the repository and create new pathways through the 
repository. New faults or the cavitation of existing faults may enhance the groundwater flow, 
thus decreasing the transport times for potentially released radionuclides. 
Disposition: Include effects of present-day faults. Exclude the effects of changes to the faults 
on the basis of low consequence. 
Screening Argument: Like fractures, faulting is a characteristic feature of Yucca Mountain 
geology. The present-day faults are directly included in the flow and transport models of the 
unsaturated zone (CRWMS M&O 2000l; Section 6). Fault movements can affect the fracture 
properties through changes in rock stress. This aspect of the problem is discussed in Section 
6.7.1. Fault movements can also change the properties of the faults themselves, and this aspect 
has been investigated with a sensitivity study (CRWMS M&O 2000e; Section 6). This study 
found that radionuclide transport in the unsaturated zone is very insensitive to the fault 
properties. Because waste emplacement drifts are not located in fault zones, there are no effects 
of changes in fault properties on drift seepage. Thus we exclude the effects of changes in fault 
properties in TSPA. 
Another aspect of faulting that could be important is the formation of new faults, particularly 
within the repository block. However, CRWMS M&O (1998b; Figure 8-8, 8-9, and 8-10) 
indicates that the probability of new fault movements along small faults (with 2 meter 
displacement) have a annual exceedance probability for movement of more than 1 m to be less 
than 10-4 in 10,000 years. Therefore small faults will remain small. The magnitude of potential 
future displacements along faults with smaller present-day displacements or along fractures are 
likewise smaller. Therefore, the effects of new faults are expected to be negligible and are 
excluded from TSPA. 
6.7.3 Seismic Activity (1.2.03.01.00) 
YMP Primary FEP Description: Seismic activity (i.e., earthquakes) could produce jointedrock 
motion, rapid fault growth, slow fault growth or new fault formation, resulting in changes in 
hydraulic heads, changes in groundwater recharge or discharge zones, changes in rock stresses, 
and severe disruption of the integrity of the drifts (e.g., vibration damage, rockfall).

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Disposition: Exclude on the basis of low consequence. 
Screening Argument: The relevant aspects of this FEP with respect to the unsaturated zone 
have been discussed in Sections 6.7.1 and 6.7.2. The effects of seismic activity on fractures are 
found to have low consequence for both mountain-scale radionuclide transport and for seepage 
into waste emplacement drifts. Changes to fault properties are found to have low consequence 
on performance issues concerning radionuclide transport and drift seepage. Finally, the 
formation of new faults or enhancement of small faults into major faults are found to have an 
annual exceedance probability of less than 10-8. Therefore, the effects of changes to the fracture 
system and faults have been excluded in the TSPA on the basis of low consequence and low 
probability. 
6.7.4 Igneous Activity Causes Changes to Rock Properties (1.2.04.02.00) 
YMP Primary FEP Description: Igneous activity near the underground facility causes 
extreme changes to rock hydrologic and mineralogic properties. Permeabilities of dikes and sills 
and the heated regions immediately around them can differ from those of country rock. Mineral 
alterations can also change the chemical response to contaminants. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: Basaltic igneous activity typically has minimal physical and 
mineralogical effects on local rock properties. Basalt magma chills rapidly against country rock, 
forming a non-vesicular apahanitic border facies having low thermal conductivity and low 
chemical reactivity. The country rock itself may be baked to form a thin rind or hornfels. It is 
unlikely that contact mineral alterations would change the chemical response to contaminants, as 
alteration usually results in only a dense screen of aphanitic anhydrous silicate minerals. Any 
such alteration in the welded tuff units would be minimal owing to the dearth of hydrous 
minerals and the large component of high-temperature feldspars in the tuff. However, basalt 
contact with nonwelded units rich in zeolites might produce a significant zone of alteration. In 
this case, a barrier to groundwater flow might be appreciable in a rock that has relatively high 
pore permeability. Unlike siliceous alteration associated with granitic magma, thermal alteration 
associated with basalts is narrowly confined and of short duration. An insignificant amount of 
volatiles enters the host rock from the cooling basalt dike. A dike intersecting the saturated zone 
will freeze against the bedrock. At this point the magma is degassing and crystallizing - it will 
not absorb groundwater nor form a local hydrothermal cell. Therefore, the thermal and chemical 
effects would be very local and transient, lasting at most for several days to several months, and 
not extending for more than a meter or two from the dike margin. On the basis of these confined 
and short duration features and processes, this FEP is excluded on basis of low consequence. 
6.7.5 Hydrothermal Activity (1.2.06.00.00) 
YMP Primary FEP Description: This category contains FEPs associated with naturallyoccurring 
high-temperature groundwaters, including processes such as density-driven 
groundwater flow and hydrothermal alteration of minerals in the rocks through which the high 
temperature groundwater flows. 
Disposition: Exclude on the basis of low probability.

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Screening Argument: Hydrothermal activity refers to the alteration or precipitation of minerals 
in the presence of hot water, generally below 400C. Hydrothermal activity is usually 
characterized by replacement assemblages or vein deposits of silica and calcite and clay 
minerals, and by sulfides such as pyrite. Hydrothermal activity usually represents the last 
cooling stage of magmatic intrusion when residual water is passed from the crystallizing melt, 
and/or its heat flux is sufficient to set up local deep groundwater convection such that hot, 
mineral laden solutions pass upwards to cool and precipitate in a halo around the intrusion; the 
country rock literally stews in hot fluid for periods of hundreds to thousands of years. 
Hydrothermal mineralization is not to be confused with deuteric alteration, which has affected 
the tuffs at Yucca Mountain. In this case, as the tuffs cooled and devolatized, aqueous or 
gaseous components exsolved from the tuff and precipitated calcite, opal, or zeolites, especially 
in lithophysae and less commonly in small, discontinuous veins. Many of these late minerals 
have fluid inclusions that indicate elevated temperatures, or hydrothermal conditions, but they do 
not indicate operation of a hydrothermal system of alteration. 
Hydrothermal activity is conspicuous in the Calico Hills and along the south flank of Shoshone 
Mountain, but comparable hydrothermal activity has not been identified at Yucca Mountain. 
The Calico Hills is an intrusion-related dome, but Yucca Mountain is located outside the caldera 
margin, hence it was never near a hydrothermal source (CRWMS M&O 1998a, Figure 3.5-2). 
Unless it could be demonstrated that major silicic magmatism is imminent near Yucca Mountain, 
there is no possibility for future hydrothermal activity at or near the mountain (Assumption 7). 
Therefore, the effects of hydrothermal activity are excluded from TSPA on the basis of low 
probability. 
6.7.6 Hydrological Response To Seismic Activity (1.2.10.01.00) 
YMP Primary FEP Description: Seismic activity, associated with fault movement, may 
create new or enhanced flow pathways and/or connections between stratigraphic units, or it may 
change the stress (and therefore fluid pressure) within the rock. These responses have the 
potential to significantly change the surface- and groundwater flow directions, water level, water 
chemistry and temperature. 
Disposition: Exclude on the basis of low consequence and low probability. 
Screening Argument: This FEP includes the effects of seismic activity on unsaturated zone 
flow and transport at the mountain scale and for drift seepage. It also includes the possible water 
table rise in response to seismic activity. The aspects of this FEP related to flow and transport 
are addressed in Sections 6.7.1, 6.7.2, and 6.7.3. Here we assess the effects of seismically 
induced water table rise. 
Seismic pumping (Szymanski, 1989; p 3-22) is the temporary increase in height of the water 
table caused by fault movement. This movement of the water table is caused by the opening and 
closing of fractures during an earthquake cycle. The observed similarity that exists among the 
hydrologic signatures both close to and far from the seismic slip suggests that the population of 
fractures are not significantly affected by proximity to the active fault (Muir-Wood and King, 
1993; p. 22061). Longer term changes are due to complex strain adjustments, but these changes 
are dissipated under the influence of regional stress field, which brings the state of the SZ 
fracture network back to an ambient, pre-seismic state as postseismic relaxation occurs. 
Numerical simulations by Carrigan et al. (1991) of tectonohydrologic coupling involving

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earthquakes typical of the Basin and Range province (~ 1 m slip) produced 2 to 3 m excursions 
of a water table 500 m below ground surface. Extrapolation to an event of about 4 m slip would 
result in a transient rise of 17 m near the fault (Carrigan et al. 1991; p. 1159). Changes in water 
table along faults is a different story, as permeability along the fault plane is drastically altered 
by seismic slip (Bruhn, 1994). This phenomenon results in seismic pumping. Carrigan et al. 
(1991) modeled a 100-m wide fracture zone centered on a vertical fault, such that vertical 
permeability was increased 103. Water level excursions in the fracture zone was twice the 
amplitude as that in the adjacent block. For a fault-fracture zone with 1 m slip, transient 
excursions of about 12 m can occur. 
Data and modeling results indicate that changes in water table elevation at Yucca Mountain are 
not likely to exceed several meters and are likely to be transient. Furthermore, distant 
earthquakes can cause high amplitude excursions. Fault slip at block bounding faults at Yucca 
Mountain could result in higher water table excursions along the faults because of seismic 
pumping. The very complex structure of the Paleozoic aquifer beneath Yucca Mountain makes 
any generalization of water table behavior impossible; local rise is as likely as local fall. What 
seems most reasonable is that the water table excursions due to earthquakes are very unlikely to 
threaten, even temporarily, the repository horizon. Therefore, the seismic effects on water table 
rise due to seismic pumping are excluded from TSPA on the basis of low consequence. 
Another aspect of the water-table rise issue concerns the large hydraulic gradient. A large 
hydraulic gradient in the water table currently exists north of the potential repository. The water 
table quickly drops across this large hydraulic gradient by about 250 m. If this gradient could 
migrate southward, the resulting water table below the potential repository could be much higher 
than present-day conditions. For example, the work of Davies and Archambeau (1997; p.28) 
suggests that the gradient is a result of stress variations in the rock that are residual stress effects 
induced by the Timber Mountain caldera. Furthermore, they suggest that moderate earthquakes 
in this area could induce a sufficient change in geomechanical strain downstream of the current 
large hydraulic gradient to induce a similar gradient downstream of the potential repository, 
resulting in a large (150 m to 250 m) rise in the water table beneath the potential repository. 
However, the hypothesis regarding the residual stress effects of the 10 million-year (Ma) Timber 
Mountain caldera contradicts extensive previous experience in the region of the Nevada Test Site (Stock et 
al. 1985). This composite experience is compiled from 14 sources reporting results from diverse 
methods including hydraulic fracturing, overcoring stress measurements, earthquake focal 
mechanisms, borehole breakouts, orientations of explosion-produced fractures, and study of 
Quaternary faults and cinder-cone alignments. These studies show a reasonably uniform direction of 
extension between NW and W, with a mixed potential-slip regime of normal faulting (mainly for 
shallow indicators) and strike-slip faulting (mainly for deep indicators). The Davies and 
Archambeau discussion is also inconsistent with actual stress measurements in G-2 as reported by 
Stock and Healy (1988), which is cited, though erroneously, as a source of "slug-test" data. Stock 
and Healy (1988) characterize G-2 as being within the same ("combined normal and strike-slip") 
faulting regime as that indicated by the results from the three holes that they tested south of the 
large gradient. In fact, based on the stress measurements in the four holes, the tendency for strikeslip 
faulting is greatest in the southeastern hole, UE-25p#1, not in the northern Yucca Mountain area 
where G-2 is located as Davies and Archambeau propose. The actual data do not support a residual 
stress effect from the Timber Mountain caldera, do not support a modern stress field changing from 
strike-slip in northern Yucca Mountain to normal south of the hydraulic gradient, and do not support 
a southward decrease of the least principal stress. Although it is reasonable that the area of the

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ANL-NBS-MD-000001 REV 00 56 of 77 March 2000 
large hydraulic gradient is less transmissive than the area to the south-southeast, a more reasonable 
explanation for this lower transmissivity is that durable differences of lithology, alteration history, and 
structural deformation have affected this region, rather than a transient state of stress (Assumption 8). 
Therefore, the seismic effects on water table rise due to migration of the large hydraulic gradient 
are excluded from TSPA on the basis of low probability. 
6.7.7 Hydrologic Response to Igneous Activity (1.2.10.02.00) 
YMP Primary FEP Description: Igneous activity may change the groundwater flow 
directions, water level, water chemistry and temperature. Igneous activity includes magmatic 
intrusions which may change rock properties and flow pathways, and thermal effects which may 
heat up groundwater and rock. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: If lava were to dam one or more washes that drain the repository block 
the dam would probably not produce a large surface-water impoundment. Given the abundant 
unconsolidated channel and bank sediment and extensive colluvium in or near washes at Yucca 
Mountain, it is more likely that streams would grade by means of alluvial deposition to the lava 
dam spillway within a few decades. Such lava dams would probably not be effective in any 
case, as the lava would consist of clinker or aa (aa is a lava flow with a surface typified by 
angular, jagged blocks). Another potential effect (for which no data exist) would be the 
deposition of an ash cover on the repository block. This could increase infiltration since overland 
flow and sheet wash for all but the largest rainfall events might be appreciably inhibited by the 
highly porous ash or cinder blanket. However, unconsolidated ash a few centimeters thick likely 
would not last for more than a century. 
Intrusion of a basalt dike at or near the repository block could present a radical contrast in 
hydrologic properties to the native rock, as it is likely that the basalt would have few, if any, 
fractures comparable to those of the tuff, and essentially no pore permeability. The net effect of 
dike intrusion would seem to be a rise in up-gradient water table but the effect should be strongly 
dependent on dike attitude and lateral continuity of a dike or dike swarm. Thus, even a relatively 
thin (several cm thick) subvertical dike oriented normal to the local flow gradient could, over 
time, create a groundwater dam. An important feature of some dike intrusions is collateral 
fracturing due to minor shear. This is significant because it can create pathways adjacent to the 
dike, augmenting hydrologic damming on the up-gradient side and perhaps draining perched 
water adjacent to a dike. The effects of perched water drainage are discussed in Section 6.7.9, 
with the conclusion that drainage of perched water is expected to have low consequence. 
Exposure of the 3.7 Ma basalt dikes in Crater Flat show an earlier sheared and fractured dike that 
has been cross cut at an acute angle by a later, less fractured dike. Generations of dikes affected 
by local deformation events that attend successive intrusive events could produce complex 
intersections of variably fractured dikes that both dam and afford complex pathways to 
groundwater flow. The mechanisms and the geometries are difficult to envision but could have 
some effects during times of high infiltration. Most likely, a proximal volcanic center would be 
located west or south of the repository block. Therefore, lava flows are not likely to ride up on 
the block. Any effects of such blockage on water table elevation are expected to have low 
consequence. Therefore this FEP is excluded on basis of low consequence.

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6.7.8 Changes in Stress (Due to Thermal, Seismic, or Tectonic Effects) Produce Change 
in Permeability of Faults (2.2.06.02.00) 
YMP Primary FEP Description: Stress changes due to thermal, tectonic and seismic 
processes result in strains that alter the permeability along and across faults. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: This FEP is similar in content to the one discussed in Section 6.7.2. Like 
fractures, faulting is a characteristic feature of Yucca Mountain geology. The present-day faults 
are directly included in the flow and transport models of the unsaturated zone (CRWMS M&O 
2000l; Section 6). Fault movements can affect the fracture properties through changes in rock 
stress. This aspect of the problem is discussed in Section 6.7.1. Fault movements can also 
change the properties of the faults themselves, and this aspect has been investigated with a 
sensitivity study (CRWMS M&O 2000e; Section 6). This study found that radionuclide 
transport in the unsaturated zone is very insensitive to the fault properties. Because waste 
emplacement drifts are not located in fault zones, there are no effects of changes in fault 
properties on drift seepage. Thus we exclude the effects of changes in fault properties in TSPA. 
6.7.9 Changes in Stress (Due to Seismic or Tectonic Effects) Alter Perched Water Zones 
(2.2.06.03.00) 
YMP Primary FEP Description: Strain caused by stress changes from tectonic or seismic 
events alters the rock permeabilities that allow formation and persistence of perched water zones. 
Disposition: Exclude effects of perched water changes below the potential repository on the 
basis of low consequence. Include effects of perched water changes above potential repository 
on drift seepage. 
Screening Argument: No perched water has been found in site characterization boreholes or 
through other observations in the footprint of the potential repository at elevations higher than 
potential waste emplacement. However, the generation of perched water above the potential 
repository as a result of seismic activity could potentially affect the flow of water to waste 
emplacement drifts. This potential effect is indirectly included using a model for flow focusing 
in the seepage model abstraction, as discussed in CRWMS M&O (1990o). 
Perched water zones below the elevation of the potential repository have been found in site 
characterization boreholes. The potential to release perched water as a result of stress changes 
and fracture openings driven by seismic activity should be considered. In that regard, the major 
bounding scenario identified for TSPA is the sudden release of perched water, along with its 
mobile radionuclides (Assumption 9). Although this may only have a small effect on the 
ultimate cumulative releases of radionuclides to the saturated zone, it could focus the 
radionuclide releases in a relatively sharp pulse when the perched water is allowed to drain. 
This possibility has been investigated by considering the volume of perched water in the fracture 
domain below the potential repository. The perched water in the fracture domain is the relevant 
feature because it is this volume that could potentially be quickly released to the saturated zone. 
Perched water in the matrix domain would also ultimately drain to the saturated zone, but this 
would be much slower and unlikely to cause any temporal pulses of radionuclide flux at the 
water table. The unsaturated zone flow model shows that the volume of perched water in the

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ANL-NBS-MD-000001 REV 00 58 of 77 March 2000 
fracture domain below the potential repository ranges from about 3800 m3 to 514,000 m3. This 
volume may be compared with the water flux entering the potential repository footprint (i.e. that 
average infiltration rate times the area of the repository footprint), which ranges from 1300 m3/yr 
to 191,000 m3/yr. As shown in Attachment X, the perched water volume is seen to represent 
about from 0.4 to 55 years of water flux. This relatively small amount of water, and the 
radionuclides that could be contained in this water, is not expected to cause a significant pulse 
in radionuclide mass flux at the water table. Therefore, the effects of changes in perched water 
due to seismic effects are excluded from TSPA on the basis of either low probability (formation 
of new perched water) or low consequence (drainage of existing perched water). 
6.7.10 Undetected Features (in Geosphere) (2.2.12.00.00) 
YMP Primary FEP Description: This category contains FEPs related to undetected features 
in the geosphere that can affect long-term performance of the disposal system. Undetected but 
important features may be present, and have significant impacts. These features include unknown 
active fracture zones, inhomogeneities, faults and features connecting different zones of rock, 
different geometries for fracture zones and induced fractures due to the construction or presence 
of the repository. 
Disposition: Exclude on the basis of low consequence and low probability. 
Screening Argument: Two kinds of undetected features are of concern: (1) features which, on 
the basis of previous investigations, could be thought to be present, (2) features totally 
unexpected. Features that could be present include buried Plio-Pleistocene basaltic intrusions; 
these would be of such small dimension that detection by geophysical means would be difficult. 
As discussed in the Probabilistic Volcanic Hazard Analysis (PVHA) (CRWMS M&O 1996; 
Section 3), the presence of buried basalt dikes or plugs would shorten the recurrence interval of 
basaltic eruption and perhaps widen the spatial distribution of events, hence increasing the 
volcanic hazard at Yucca Mountain. Another undetected feature of considerable significance is 
the controlling structure of the large hydraulic gradient across the northern part of Yucca 
Mountain, a 300-m decline in potentiometric surface across a 2 km-width north of the potential 
repository. If the controlling feature is a fault zone rather than a facies change, tectonic 
reactivation could alter deep hydrologic flux in the vicinity of the repository. 
It is very unlikely that a major, critical feature in the vicinity of Yucca Mountain, such as a large 
seismogenic fault zone, has been overlooked during site characterization. Such tectonic features, 
including buried strike-slip fault zones or shallow detachment faults, have been considered and 
factored into tectonic models evaluated by the PSHA , (CRWMS M&O 1998b). Therefore, the 
effects of undetected features are excluded on basis of low consequence. Any undetected 
features relevant to repository performance have been considered in uncertainty and hazard 
estimates in PVHA (CRWMS M&O 1996) and PSHA (CRWMS M&O 1998b). 
6.8 REPOSITORY PERTURBED THMC 
This group of FEPs constitutes a mixture of items both included and excluded from the TSPA 
calculation. These FEPs concern the effects of repository perturbations to the 
thermal/hydrologic/mechanical/chemical environment and the effects of these perturbations on 
hydrologic and geochemical processes that may be important to repository performance.

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ANL-NBS-MD-000001 REV 00 59 of 77 March 2000 
Table 10 gives the FEP numbers for the YMP primary FEPs, the primary FEP titles, and some, 
but not all, of the secondary FEP titles for this category. Not all the secondary FEP titles are 
listed because many are identical, or nearly identical to the primary FEP title or to other 
secondary FEP titles under the same primary FEP. A listing of the description of each of the 
primary and secondary FEPs in this category is given in Attachment VIII. 
Table 10. Included/Excluded FEPs: Repository Perturbed THMC 
YMP Primary FEP Number Primary FEP Title Secondary FEPs Titles 
1.1.02.00.00 Excavation/construction  Blasting and vibration 
 Geochemical alteration 
(excavation) 
 Groundwater chemistry 
(excavation) 
 Influx of oxidizing water 
2.2.01.01.00 Excavation and construction-related 
changes in the adjacent host rock 
 Disturbed rock zone 
 Mechanical effects  
excavation/backfilling effects 
 Formation of cracks (host rock 
disturbed zone) 
 Damaged zone (host rock 
disturbed zone) 
 Excavation/backfilling effects 
on nearby rock 
 Enhanced rock fracturing 
 Creeping of rock mass, nearfield 
 Disturbed zone 
(hydromechanical effects) 
 Excavation-induced changes in 
stress 
2.2.01.05.00 Radionuclide transport in excavation 
disturbed zone 
 Radionuclide retardation 
(excavation-disturbed zone) 
 Radionuclide release from EDZ

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Table 10. Included/Excluded FEPs: Repository Perturbed THMC (continued) 
YMP Primary FEP Number Primary FEP Title Secondary FEPs Titles 
2.2.07.10.00 Condensation zone forms around 
drifts 
 Condensation cap forms above 
repository 
 Formation of condensate over 
individual containers 
 Formation of condensate over 
individual panels 
 Formation of condensate over 
entire repository 
 Shedding of condensate cap 
over one drift to another drift 
 Vault geometry 
2.2.07.11.00 Return flow from condensation cap / 
resaturation of dry-out zone 
 Auto-catalytic drainage of 
locally saturated flow thru 
condensation cap* 
 Resaturation, near-field rock 
 Return of condensate to same 
panel 
 Resaturation of dry-out zone is 
affected by vapor flow 
 Resaturation of dry-out zone is 
affected by liquid under 
capillary forces 
 Unsaturated flow plume returns 
flow from the condensation cap 
2.2.08.01.00 Groundwater chemistry / 
composition in UZ and SZ 
 Groundwater chemistry (in 
geosphere) 
 Deep saline water intrusion 
 Interface different waters (in 
geosphere) 
 Water chemistry in near-field 
rock 
 Freshwater intrusion (in 
geosphere) 
 Changes in groundwater Eh 
 Changes in groundwater pH 
 Oxidizing conditions 
 Groundwater composition 
 pH-deviations 
 Changes of groundwater 
chemistry in nearby rock 
 Effects at saline-freshwater 
interface 
 Chemical gradients 
 Non-radioactive solute plume in 
geosphere 
 Mineralogy (host rock)

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Table 10. Included/Excluded FEPs: Repository Perturbed THMC (continued) 
YMP Primary FEP Number Primary FEP Title Secondary FEPs Titles 
2.2.08.02.00 Radionuclide transport occurs in a 
carrier plume in geosphere 
 Locally saturated carrier plume 
forms (in geosphere) 
 Unsaturated carrier plume 
forms (in geosphere) 
 Precipitation/dissolution 
(release/migration factors) 
2.2.08.03.00 Geochemical interactions in 
geosphere (dissolution, 
precipitation, weathering) and 
effects on radionuclide transport 
 Far-field transport: changes in 
groundwater chemistry and 
flow direction 
 Effects of dissolution (in 
geosphere) 
 Rock property changes (in 
geosphere) 
 Hydraulic properties-evolution 
 Dissolution of fracture 
fillings/precipitation (in 
geosphere) 
 Weathering of flow paths (in 
geosphere) 
 Fracture mineralization and 
weathering (in geosphere) 
 Precipitation and dissolution 
(release/migration factors) 
 Chemical precipitation 
(release/migration factors) 
 Dissolution, precipitation, and 
crystallization 
(release/migration factors) 
 Kinetics of precipitation and 
dissolution (release/migration 
factors) 
 Speciation (contaminant 
speciation and solubility) 
 Recrystallization (contaminant 
speciation and solubility) 
 Kinetics of speciation 
(contaminant speciation and 
solubility) 
 Groundwater chemistry 
(sorption/desorption process) 
2.2.08.05.00 Osmotic processes None 
2.2.08.06.00 Complexation in geosphere None 
2.2.08.07.00 Radionuclide solubility limits in the 
geosphere 
 Solubility limits/colloid 
formation 
2.2.09.01.00 Microbial activity in geosphere  Microbes (in geosphere) 
 Microbial activity (in 
geosphere) 
 Far-field transport: 
biogeochemical changes 
 Bacteria and microbes in soil 
 Chemical transformations 
(biological processes)

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Table 10. Included/Excluded FEPs: Repository Perturbed THMC (continued) 
YMP Primary FEP Number Primary FEP Title Secondary FEPs Titles 
2.2.10.01.00 Repository-induced thermal effects 
in geosphere 
 Temperature, far-field 
 Temperature, near-field rock 
 Thermal effects on groundwater 
flow 
 Groundwater evolution 
 Thermal effects on material 
properties (in waste and 
engineered barrier system) 
 Thermal effects: rock mass 
changes 
 Thermal effects: 
hydrogeological changes 
2.2.10.04.00 Thermo-mechanical alteration of 
fractures near repository 
 Thermal expansion closes most 
fractures close to repository 
 Thermally-induced fracturing 
around containers creates a 
capillary barrier 
 Host rock fracture aperture 
changes 
2.2.10.05.00 Thermo-mechanical alteration of 
rocks above and below the 
repository 
 Thermal expansion of rocks 
below repository opens 
fractures in Paintbrush 
nonwelded 
 Thermo-mechanical alteration 
of surface infiltration 
2.2.10.06.00 Thermo-chemical alteration 
(solubility, speciation, phase 
changes, precipitation/dissolution) 
 Silica phase changes 
(accompanied by volume 
change) occur due to elevated 
temperature 
 Thermochemical change 
 Alteration of rock properties 
because of 2-phase flow 
 Heat-induced chemical 
reactions plug small fractures; 
flow is preferentially redirected 
to large fractures 
 Alteration of minerals to clays 
(in geosphere) 
 Calcite precipitation in hot 
regions produces fluids 
depleted in calcite which 
dissolve calcite below the 
repository 
 Precipitates from dissolved 
constituents of tuff and 
repository materials form by 
evaporation during thermal 
period 
2.2.10.07.00 Thermo-chemical alteration of the 
Calico Hills unit 
None

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Table 10. Included/Excluded FEPs: Repository Perturbed THMC (continued) 
YMP Primary FEP Number Primary FEP Title Secondary FEPs Titles 
2.2.10.09.00 Thermo-chemical alteration of the 
Topopah Spring basal vitrophyre 
 Formation of perched water on 
the altered Topopah Spring 
basal vitrophyre 
 Sorption of contaminants by the 
altered Topopah Spring basal 
vitrophyre 
 Redirection of transport paths 
by the altered Topopah Spring 
basal vitrophyre 
 Sorption of actinides on altered 
Topopah Spring basal 
vitrophyre 
 Alteration of the Topopah 
Spring basal vitrophyre 
6.8.1 Excavation/Construction (1.1.02.00.00) 
YMP Primary FEP Description: This category contains FEPs related to the excavation of 
the underground regions of the repository, and effects of this excavation on the long-term 
behavior of the engineered and natural barriers. Excavation-related effects include changes to 
rock properties due to boring and blasting and geochemical changes to rock and groundwater. 
Disposition: Include the effects of stress relief and ground support on drift seepage. Exclude 
changes in water chemistry on the basis of low consequence. 
Screening Argument: This FEP concerns the changes in the host rock environment 
immediately surrounding the waste emplacement drifts. Changes are expected in the rock 
fracture properties due to excavation disturbance and stress relief around the opening. Also, the 
ground support for the emplacement drifts can affect water flow patterns in the immediate 
vicinity of the drift and can affect the aqueous geochemistry in the drift environment and along 
flow pathways from the drift to the water table. Changes in fracture properties due to excavation 
disturbance, stress relief, and ground support are included in the analyses for drift seepage 
(CRWMS M&O 2000g; Section 6). Changes in water chemistry entering the drift due to 
excavation/construction effects are expected to be negligible. Therefore, this aspect is excluded 
on the basis of low consequence. 
6.8.2 Excavation and Construction-Related Changes in the Adjacent Host Rock 
(2.2.01.01.00) 
YMP Primary FEP Description: Excavation will produce some disturbance of the rocks 
surrounding the drifts due to stress relief. Stresses associated directly with excavation (e.g., 
boring and blasting operations) may also cause some changes in rock properties. Properties that 
may be affected include rock strength, fracture spacing and block size, and hydrologic properties 
such as permeability. 
Disposition: Include the effects of stress relief and ground support on drift seepage. Exclude 
changes in water chemistry on the basis of low consequence.

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Screening Argument: This FEP concerns the effects of excavation and construction-related 
disturbances in the host rock adjacent to the waste emplacement drifts. This is basically the 
same issue raised in Section 6.8.1. Changes are expected in the rock fracture properties due to 
excavation disturbance and stress relief around the opening. Also, the ground support for the 
emplacement drifts can affect water flow patterns in the immediate vicinity of the drift and can 
affect the aqueous geochemistry in the drift environment and along flow pathways from the drift 
to the water table. Changes in fracture properties due to excavation disturbance, stress relief, and 
ground support are included in the analyses for drift seepage (CRWMS M&O 2000g; Section 6). 
Changes in water chemistry entering the drift due to excavation/construction effects are expected 
to be negligible. Therefore, this aspect is excluded on the basis of low consequence. 
6.8.3 Radionuclide Transport in Excavation Disturbed Zone (2.2.01.05.00) 
YMP Primary FEP Description: Radionuclide transport through the excavation disturbed 
zone may differ from transport in the waste and EBS and the undisturbed host rock. Transport 
processes such as dissolution and precipitation, sorption, and colloid filtration should be 
considered. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: This FEP refers to the effects of altered fracture properties in the 
disturbed zone immediately surrounding the waste emplacement drifts on radionuclide transport. 
The effects of changes in fracture aperture on radionuclide transport were investigated at the 
mountain-scale (CRWMS M&O 2000e; Section 6). The results of this analysis find that the 
transport behavior is relatively insensitive to changes in fracture aperture by as much as a factor 
of 10. Therefore, the effects of locally disturbed fractures should have even less effect on 
radionuclide transport processes. Precipitation of aqueous radionuclides and colloid filtration in 
fractures are conservatively ignored in the TSPA transport model. Therefore, the effects of this 
FEP on TSPA are excluded on the basis of low consequence. 
6.8.4 Condensation Zone Forms Around Drifts (2.2.07.10.00) 
YMP Primary FEP Description: Condensation of the 2-phase flow generated by repository 
heat forms in the rock where the temperature drops below the local vaporization temperature. 
Waste package emplacement geometry and thermal loading will affect the scale at which 
condensation caps form (over waste packages, over panels, or over the entire repository), and the 
extent to which "shedding" will occur as water flows from the region above one drift to the 
region above another drift or into the rock between drifts. 
Disposition: Exclude mountain-scale effects on the basis of low consequence. Include effects 
on drift seepage. 
Screening Argument: Condensation is included in the thermal-hydrologic process model that 
describes the effects of waste heat on the potential repository and surrounding natural system 
(CRWMS M&O 2000f; Section 6). The flow behavior predicted by the thermal-hydrologic 
models are incorporated into drift seepage model abstraction (CRWMS M&O 2000o; Section 6). 
The drift-scale flow model abstraction accounts for flow volumes and flow focusing under flow 
conditions perturbed by thermal-hydrologic flow processes. The effects of these processes on

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mountain-scale flow are expected to be minimal (Assumption 13). Therefore, this aspect of the 
FEP is excluded from TSPA based on low consequence. 
6.8.5 Return Flow from Condensation Cap / Resaturation of Dry-Out Zone (2.2.07.11.00) 
YMP Primary FEP Description: Following the peak thermal period, water in the 
condensation cap (see FEP 2.2.07.10.00) may flow downward into the drifts. Influx of cooler 
water from above, such as might occur from episodic flow, may accelerate return flow from the 
condensation cap by lowering temperatures below the condensation point. Percolating 
groundwater (distinct from water mobilized from the condensation cap) will also contribute to 
resaturation of the dry out zone. Vapor flow, as distinct from liquid flow by capillary processes, 
may also contribute. Water chemistry in the resaturation period may be affected by processes in 
the condensation cap and dry-out zone. 
Disposition: Exclude mountain-scale effects on the basis of low consequence. Include effects 
on drift seepage. 
Screening Argument: The effects of condensation formation is included in the TSPA as 
discussed in the previous FEP (2.2.07.10.00). Resaturation of the dry-out zone is included in the 
analyses treating thermal-hydrologic processes (CRWMS M&O 2000f; Section 6) and the 
model abstraction for drift seepage (CRWMS M&O 2000o; Section 6) and coupled-processes. 
The effects on mountain-scale flow are expected to be minimal (Assumption 13). Therefore, this 
aspect of the FEP is excluded from TSPA based on low consequence. The effects of episodic 
transient infiltration on resaturation are expected to be minimal because episodic transient flow is 
damped out in the Paintbrush nonwelded hydrogeologic unit (see Section 6.3.5). 
6.8.6 Groundwater Chemistry / Composition in UZ And SZ (2.2.08.01.00) 
YMP Primary FEP Description: Chemistry and other characteristics of groundwater in the 
saturated and unsaturated zones may affect groundwater flow and radionuclide transport. 
Groundwater chemistry and other characteristics, including temperature, pH, Eh, ionic strength, 
and major ionic concentrations, may vary spatially throughout the system as a result of different 
rock mineralogy, and may also change through time, as a result of the evolution of the disposal 
system or from mixing with other waters. 
Disposition: Include the effects of ambient-condition geochemistry. Exclude changes in 
geochemical conditions on the basis of low consequence. 
Screening Argument: As discussed in Section 6.1.15, ambient-condition geochemical effects 
are included in the TSPA model for radionuclide sorption (CRWMS M&O 2000j; Section 6 and 
2000q; Section 6). Important changes to groundwater chemistry in the post-closure repository 
environment are likely to be the result of the thermo-chemical interactions of the repository with 
the water and minerals in the unsaturated zone (Assumption 10). The thermo-chemical 
interactions that will occur in the repository environment have been studied with respect to 
effects on the seepage water entering the waste emplacement drifts (CRWMS M&O 2000s; 
Section 6). Chemical composition and hydrologic properties were found in this study to change 
only slightly as a result of these interactions. This includes the effects of dissolution and 
precipitation of minerals in fractures and matrix. Because these interactions were studied in the 
vicinity of the waste emplacement drifts where thermo-chemical interactions are expected to be

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ANL-NBS-MD-000001 REV 00 66 of 77 March 2000 
more severe, it is assumed that the effects of thermo-chemical interactions along the pathways of 
aqueous radionuclides in the unsaturated zone will also be small (Assumption 11). Therefore the 
effects of these changes are excluded from TSPA on the basis of low consequence. 
6.8.7 Radionuclide Transport Occurs in a Carrier Plume in Geosphere (2.2.08.02.00) 
YMP Primary FEP Description: Radionuclide transport occurs in a carrier plume in the 
geosphere. Transport may be as dissolved or colloidal species, and transport may occur in both 
the unsaturated and saturated zone. See also FEPs 2.1.09.01.00 (carrier plume forms in waste and 
EBS), 2.2.08.01.00 (groundwater chemistry / composition) and 2.2.08.03.00 (geochemical 
interactions). 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: This FEP is similar in content to the one discussed in Section 6.8.6. The 
thermo-chemical interactions that will occur in the repository environment have been studied 
with respect to effects on the seepage water entering the waste emplacement drifts (CRWMS 
M&O 2000s; Section 6). Chemical composition and hydrologic properties were found in this 
study to change only slightly as a result of these interactions. This includes the effects of 
dissolution and precipitation of minerals in fractures and matrix. Because these interactions were 
studied in the vicinity of the waste emplacement drifts where thermo-chemical interactions are 
expected to be more severe, it is assumed that the effects of thermo-chemical interactions along 
the pathways of aqueous radionuclides in the unsaturated zone will also be small (Assumption 
11). Therefore the effects of these changes are excluded from TSPA on the basis of low 
consequence. 
6.8.8 Geochemical Interactions in Geosphere (Dissolution, Precipitation, Weathering) and 
Effects on Radionuclide Transport (2.2.08.03.00) 
YMP Primary FEP Description: Geochemical interactions may lead to dissolution and 
precipitation of minerals along the groundwater flow path, affecting groundwater flow, rock 
properties and sorption on contaminants. These interactions may result from the evolution of 
disposal system or from external processes such as weathering. Effects on hydrologic flow 
properties of the rock, radionuclide solubilities, sorption processes, and colloidal transport are 
relevant. Kinetics of chemical reactions should be considered in the context of the time-scale of 
concern. See also FEP 2.2.08.01.00 for a discussion of groundwater chemistry and composition, 
FEP 2.2.08.07.00 for a discussion of solubility limits in the geosphere, FEP 2.2.08.09.00 for a 
discussion of sorption in the geosphere, and FEPs 2.2.08.10.00 and 2.2.08.10.01 for a discussion 
of colloidal transport . 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: This FEP is similar in content to the one discussed in Section 6.8.7. The 
thermo-chemical interactions that will occur in the repository environment have been studied 
with respect to effects on the seepage water entering the waste emplacement drifts (CRWMS 
M&O 2000s; Section 6). Chemical composition and hydrologic properties were found in this 
study to change only slightly as a result of these interactions. This includes the effects of 
dissolution and precipitation of minerals in fractures and matrix. Because these interactions were 
studied in the vicinity of the waste emplacement drifts where thermo-chemical interactions are

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 67 of 77 March 2000 
expected to be more severe, it is assumed that the effects of thermo-chemical interactions along 
the pathways of aqueous radionuclides in the unsaturated zone will also be small (Assumption 
11). Therefore the effects of these changes are excluded from TSPA on the basis of low 
consequence. 
6.8.9 Osmotic Processes (2.2.08.05.00) 
YMP Primary FEP Description: Osmotic processes in response to chemical gradients could 
affect radionuclide transport in the geosphere. See also FEP 2.2.08.08.00, matrix diffusion. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: Osmosis would tend to cause water from fractures to flow into matrix, if 
the matrix presents a suitable barrier to the migration of dissolved salts. This process is 
expected to be negligible at Yucca Mountain and is conservatively ignored in TSPA. 
6.8.10 Complexation in Geosphere (2.2.08.06.00) 
YMP Primary FEP Description: Complexing agents such as humic and fulvic acids present 
in natural groundwaters could affect radionuclide transport. See also FEP 2.1.09.13.00 for a 
discussion of complexing agents in the waste and EBS. 
Disposition: Include effects of ambient-condition complexation. Exclude effects of changes to 
complex formation due to changes in geochemical conditions on the basis of low consequence. 
Screening Argument: This FEP refers to the geochemical interactions between ligands and 
metal ions, particularly radionuclides. Complexation is expected to occur under post-closure 
repository conditions. For ambient conditions this phenomenon is implicitly included in the 
radionuclide sorption coefficients (see Section 6.1.15). Thermo-chemical interactions due to 
repository heat and materials interactions may alter the geochemical environment, including the 
ligands that interact with radionuclides. Although the effects of ligands on radionuclides were 
not investigated in the near-field thermo-chemical modeling study (CRWMS M&O 2000s; 
Section 6), the general results of the modeling study indicate that the changes in geochemistry 
driven by thermo-chemical interactions are not large. If changes in the geochemistry are 
generally small, then the effects of ligands on radionuclide transport should also be small 
(Assumption 11). Therefore, this FEP is excluded from TSPA on the basis of low consequence. 
6.8.11 Radionuclide Solubility Limits in the Geosphere (2.2.08.07.00) 
YMP Primary FEP Description: Solubility limits for radionuclides may different in 
geosphere groundwater than in the water in the waste and EBS. See also FEP 2.2.08.01.00 for a 
discussion of groundwater chemistry and FEP 2.1.09.04.00 for a discussion of solubility limits in 
the waste and EBS. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: This FEP is conservatively ignored with respect to solubility reduction in 
the far-field; the effects of radionuclide precipitation are ignored in the far-field unsaturated zone 
transport problem for TSPA. The effects of colloid formation are accounted for in the colloid 
source term. Colloids are expected to be formed from the dissolution of glass waste and from

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 68 of 77 March 2000 
natural colloidal materials. Radionuclides associated with colloids are assumed to be either 
irreversibly or reversibly attached to colloids (CRWMS M&O 2000q; Section 6 and CRWMS 
M&O 2000k; Section 6). Therefore, this FEP is excluded from TSPA on the basis of low 
consequence. 
6.8.12 Microbial Activity in Geosphere (2.2.09.01.00) 
YMP Primary FEP Description: Microbial activity in the geosphere may affect radionuclide 
mobility in rock and soil through colloidal processes, by influencing the availability of 
complexing agents, or by influencing groundwater chemistry. See also FEP 2.2.08.10.00 for a 
discussion of colloidal transport and 2.2.08.06.00 for a discussion of complexing agents. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: The effects of microbial activity and other dissolved organic matter are 
expected to have a negligible influence on repository performance due to the low amounts of 
such materials emplaced or generated in the post-closure repository environment (CRWMS 
M&O 2000y; Section 6) (Assumption 12). Colloidal activity, radionuclide speciation, and 
complexation are expected to be controlled by inorganic constituents generated by the waste 
forms or by natural inorganic ligands. Therefore, this FEP is excluded from TSPA on the basis 
of low consequence. 
6.8.13 Repository-Induced Thermal Effects in Geosphere (2.2.10.01.00) 
YMP Primary FEP Description: Thermal effects in the geosphere could affect the long-term 
performance of the disposal system. Thermal effects are most important in waste, engineered 
barrier system, and the disturbed zone surrounding the excavation. See FEPs 2.1.11.00.00 and 
2.2.01.00.00 for discussions of this region. See other FEPs in this section for specific discussions 
of thermal effects in geosphere, including effects on saturated and unsaturated groundwater flow, 
mechanical properties, and chemical effects. 
Disposition: Exclude mountain-scale thermo-chemical effects on the basis of low consequence. 
Include thermo-chemical effects on drift seepage. 
Screening Argument: The effects of repository-induced thermal effects on flow are included 
for drift seepage (see Section 6.8.4). The effects on drift seepage chemistry are included. These 
effects are expected to be much less important for mountain-scale flow, as discussed in Section 
6.8.4. Any changes resulting from thermo-chemical effects are expected to be bounded by the 
results of the near-field thermo-chemical modeling study (CRWMS M&O 2000s; Section 6) 
(Assumption 11). The general results of the near-field thermo-chemical modeling study indicate 
that the changes in geochemistry driven by thermo-chemical interactions are not large. 
Furthermore, any thermo-chemical effects are expected to decrease with time as the thermal 
energy of the repository is spent. Radionuclide transport will be more important as time 
increases due to the large inventory of radionuclides that will become available over time. 
Therefore the repository-induced thermo-chemical effects at the mountain scale are excluded 
from TSPA on the basis of low consequence.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 69 of 77 March 2000 
6.8.14 Thermo-Mechanical Alteration of Fractures Near Repository (2.2.10.04.00) 
YMP Primary FEP Description: Heat from the waste causes thermal expansion of the 
surrounding rock, generating changes in the stress field that may change the material properties 
(both hydrologic and mechanical) of fractures in the rock. Cooling following the peak thermal 
period will also change the stress field, further affecting rock properties near the repository. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: The main compressive stresses caused by thermo-mechanical effects will 
occur during the period when temperatures are increasing. Drift seepage is not expected during 
this time period when temperatures are increasing because water is boiled and removed as vapor 
flow from the vicinity of the waste emplacement drifts. The effects of thermo-mechanical stress 
around the waste emplacement drifts are expected to be small by the time water is present to 
seep into the drifts (Assumption 14). Therefore, this FEP is excluded from TSPA on the basis of 
low consequence. 
6.8.15 Thermo-Mechanical Alteration of Rocks Above and Below the Repository 
(2.2.10.05.00) 
YMP Primary FEP Description: Thermo-mechanical compression at the repository produces 
tension-fracturing in the PTn and other units above the repository. These fractures alter 
unsaturated zone flow between the surface and the repository. Extreme fracturing may propagate 
to the surface, affecting infiltration. Thermal fracturing in rocks below the repository affects flow 
and radionuclide transport to the saturated zone. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: The effects of mechanical disturbance of fractures along radionuclide 
transport pathways is discussed in Section 6.7.1. The conclusion reached in that section is that 
the effects of changes to fracture aperture or spacing on radionuclide transport is expected to be 
negligible. In this case, the disturbance is caused by thermo-mechanical effects rather than a 
seismic event. However, the conclusions reached in Section 6.7.1 are also applicable here. 
Therefore, this FEP is excluded from TSPA on the basis of low consequence. 
The effects of changes in fracture properties above the potential repository could influence the 
pattern of flow from the surface to the waste emplacement drifts. Changes in fracture properties 
could lead to focused flow on waste emplacement drifts. The effects of focused flow have been 
included in the drift seepage model (see Section 6.1.10). 
6.8.16 Thermo-Chemical Alteration (Solubility, Speciation, Phase Changes, 
Precipitation/Dissolution) (2.2.10.06.00) 
YMP Primary FEP Description: Thermal effects may affect radionuclide transport directly 
by causing changes radionuclide speciation and solubility in the UZ and SZ, or indirectly, by 
causing changes in host rock mineralogy that affect the flow path. Relevant processes include 
volume effects associated with silica phase changes, precipitation and dissolution of fracturefilling 
minerals (including silica and calcite), and alteration of zeolites and other minerals to 
clays.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 70 of 77 March 2000 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: This FEP raises some issues already addressed in Section 6.8.11. This 
FEP is conservatively ignored with respect to solubility reduction in the far-field; the effects of 
radionuclide precipitation are ignored in the far-field unsaturated zone transport problem for 
TSPA. The effects of colloid formation are accounted for in the colloid source term. Colloids 
are expected to be formed from the dissolution of glass waste and from natural colloidal 
materials. Radionuclides associated with colloids are assumed to be either irreversibly or 
reversibly attached to colloids (CRWMS M&O 2000q; Section 6 and CRWMS M&O 2000k; 
Section 6). The near-field thermal-chemical analysis indicates only small changes in aqueous 
geochemistry and mineralogy as a result of these coupled processes (CRWMS M&O 2000s; 
Section 6). Therefore, far-field changes are likewise expected to be small (Assumption 11), 
including mineral precipitation/dissolution and alteration of minerals such as zeolites and clays. 
Therefore, this FEP is excluded from TSPA on the basis of low consequence and low 
probability. 
6.8.17 Thermo-Chemical Alteration of the Calico Hills Unit (2.2.10.07.00) 
YMP Primary FEP Description: Fracture pathways in the Calico Hills are altered by the 
thermal and chemical properties of the water flowing out of the repository. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: The near-field thermal-chemical analysis indicates only small changes in 
aqueous geochemistry and mineralogy as a result of these coupled processes (CRWMS M&O 
2000s; Section 6). Therefore, far-field changes are likewise expected to be small (Assumption 
11), including mineral precipitation/dissolution and alteration of minerals such as zeolites and 
clays. In particular, with respect to thermal alteration of zeolites, results of the 3D mountainscale 
thermal-hydrologic calculations (CRWMS M&O 2000bb; Section 6.8.2.1) suggest that 
temperatures in the zeolite-bearing CHn will not be high enough to cause significant zeolite 
alteration. This FEP is excluded on the basis of low consequence. 
6.8.18 Thermo-Chemical Alteration of the Topopah Spring Basal Vitrophyre 
(2.2.10.09.00) 
YMP Primary FEP Description: Heating the Topopah Spring basal vitrophyre with water 
available causes alteration of the glasses to clays and zeolites. Possible effects include volume 
increases that plug fractures, changes in flow paths, creation of perched water zones, and an 
increase in the sorptive properties of the unit. 
Disposition: Exclude on the basis of low consequence. 
Screening Argument: The near-field thermal-chemical analysis indicates only small changes in 
aqueous geochemistry and mineralogy as a result of these coupled processes (CRWMS M&O 
2000s; Section 6). Therefore, far-field changes are likewise expected to be small (Assumption 
11), including mineral precipitation/dissolution and alteration of minerals such as zeolites and 
clays.. This FEP is excluded on the basis of low consequence.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 71 of 77 March 2000 
7. CONCLUSIONS 
This document presents the 515 FEPs associated with unsaturated zone flow and transport 
processes. These FEPs have been organized into 81 primary FEPs and associated 434 secondary 
FEPs. The 22 primary FEPs identified in Section 6.1, along with portions of primary FEPs 
identified in sections 6.2.1, 6.2.2, 6.2.4, 6.3.4, 6.3.5, 6.3.6, 6.3.7, 6.3.8, 6.7.1, 6.7.2, 6.7.9, 6.8.1, 
6.8.2, 6.8.4, 6.8.5, 6.8.6, 6.8.10, and 6.8.13 are included in TSPA. The portions of these 18 FEPs 
not included, along with the remaining 41 primary FEPs, are excluded from TSPA based on 
arguments presented in this document. The 434 secondary FEPs associated with these primary 
FEPs are included or excluded based on the primary FEP arguments. 
Some of the FEPs arguments for exclusion are based on assumptions that require further 
verification. All assumptions are given in Section 5, and the assumptions that require further 
verification are identified. Many of the FEP exclusion arguments that are based on assumptions 
requiring further verification are found in Section 6.8. This section concerns the effects of 
repository perturbed thermal-hydrologic-mechanical-chemical coupled processes. In particular, 
the arguments used to exclude the FEPs in Sections 6.8.4, 6.8.5, 6.8.6, 6.8.7, 6.8.8, 6.8.10, 
6.8.12, 6.8.13, 6.8.14, 6.8.17, and 6.8.18 use assumptions that require verification. In addition, 
to these FEPs from Section 6.8, the FEP exclusion arguments used in Sections 6.3.5 and 6.3.8 are 
based on assumptions that require verification. If any of these assumptions cannot be verified, 
then additional modeling work will be required to include in TSPA the FEPs that have been 
excluded based on those assumptions. 
This document and its conclusions may be affected by technical product input information that 
requires confirmation. Any changes to the document or its conclusions that may occur as a result 
of completing the confirmation activities will be reflected in subsequent revisions. The status of 
the input information quality may be confirmed by review of the Document Input Reference 
System database.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 72 of 77 March 2000 
8. REFERENCES 
DOCUMENTS CITED 
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CRWMS M&O 1997. The Site-Scale Unsaturated Zone Transport Model of Yucca Mountain. 
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CRWMS M&O 1998a. "Geology" Book 1 - Section 3 of Yucca Mountain Site Description. 
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CRWMS M&O 1998b. Probabilistic Seismic Hazard Analyses for Fault Displacement and 
Vibratory Ground Motion at Yucca Mountain, Nevada. Milestone Report SP32IM3. Three 
volumes. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.19980619.0640. 
CRWMS M&O 1998c. "Unsaturated Zone Hydrology Model." Chapter 2 of Total System 
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CRWMS M&O 1999a. Features, Events, and Processes in UZ Flow and Transport. TDP-NBSMD-
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30, 1999. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.19991028.0092. 
CRWMS M&O 1999c. Machine Readable Media Forms: Compact Disk YMP FEP Database 
Rev. 00C. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.19991214.0518. 
CRWMS M&O 2000a. not used. 
CRWMS M&O 2000b. Analysis/Model Report U0010, Simulation of Net Infiltration for Modern 
and Potential Future Climates. Input Transmittal 00082.T. Las Vegas, Nevada: CRWMS M&O. 
ACC: MOL.20000310.0071.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 73 of 77 March 2000 
CRWMS M&O 2000c. UZ Flows Models and Submodels. MDL-NBS-HS-000006 REV 00. Las 
Vegas, Nevada: CRWMS M&O. URN-0030. 
CRWMS M&O 2000d. Drift Degradation Analysis. ANL-EBS-MD-000027. Las Vegas, 
Nevada: CRWMS M&O. ACC: MOL.20000107.0328 
CRWMS M&O 2000e. Fault Displacement Effects on Transport in the Unsaturated Zone. Input 
Transmittal 00105.T. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.20000310.0343. 
CRWMS M&O 2000f. Multiscale Thermohydrologic Model. Input Transmittal 00122.T. Las 
Vegas, Nevada: CRWMS M&O. ACC: MOL.20000313.0676. 
CRWMS M&O 2000g. Seepage Models for PA Including Drift Collapse and Drainage. MDLNBS-
HS-000002 REV 00. Las Vegas, Nevada: CRWMS M&O. URN-0023. 
CRWMS M&O 2000h. Development of Numerical Grids for UZ Flow and Transport Modeling. 
ANL-NBS-HS-000015 REV 00. Las Vegas, Nevada: CRWMS M&O. ACC: 
MOL.19990721.0517. 
CRWMS M&O 2000i. Calibrated Properties Model. MDL-NBS-HS-000003 REV 00. Las 
Vegas, Nevada: CRWMS M&O. URN-0041. 
CRWMS M&O 2000j. Unsaturated Zone and Saturated Zone Transport Properties. Input 
Transmittal 00111.T Las Vegas, Nevada: CRWMS M&O. ACC: MOL.20000313.0415. 
CRWMS M&O 2000k. Unsaturated Zone Colloid Transport Model. Input Transmittal 00114.T. 
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CRWMS M&O 2000l. Conceptual and Numerical Model for Unsaturated Zone Flow and 
Transport. MDL-NDS-HS-000005 REV 00. Las Vegas, Nevada: CRWMS M&O. URN-0036. 
CRWMS M&O 2000m. Not used. 
CRWMS M&O 2000n. Analysis of Base-Case Particle Tracking Results of the Base-Case Flow 
Fields. ANL-NBS-HS-000024 REV 00. Las Vegas, Nevada: CRWMS M&O. ACC: 
MOL.20000207.0690. 
CRWMS M&O 2000o. Abstraction of Drift Seepage. ANL-NBS-MD-000005 REV 00. Las 
Vegas, Nevada: CRWMS M&O. URN-0018. 
CRWMS M&O 2000p. Not used. 
CRWMS M&O 2000q. Particle Tracking Model and Abstraction of Transport. Input 
Transmittal 00118.T. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.20000313.0609. 
CRWMS M&O 2000r. Abstraction of Near-Field Environment Drift Thermodynamic 
Environment and Percolation Flux. Input Transmittal 00103.T. Las Vegas, Nevada: CRWMS 
M&O. ACC: MOL.20000310.0340.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 74 of 77 March 2000 
CRWMS M&O 2000s. Drift Scale Coupled Processes (DST, THC Seepage) Models. MDLNBS-
HS-000001 REV 00. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.19990721.0523. 
URN-0042. 
CRWMS M&O 2000t. WAPDEG Analysis of Waste Package and Drip Shield Degradation. 
Input Transmittal 00087.T. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.20000310.0339. 
CRWMS M&O 2000u. Evaluate Soil/Radionuclide Removal by Erosion Leaching. ANL-NBSMD-
000009 REV 00. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.20000310.0057. 
CRWMS M&O 2000v. Not used. 
CRWMS M&O 2000w. Abstraction of Flow Fields for RIP (ID:U0125). ANL-NBS-HS-000023 
REV 00. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.20000127.0089. 
CRWMS M&O 2000x. Abstraction of Drift Scale Coupled Processes. ANL-NBS-HS-000029 
REV 00. Las Vegas, Nevada: CRWMS M&O. URN-0032. 
CRWMS M&O 2000y. Physical and Chemical Environment Abstraction Model. Input 
Transmittal 00106.T. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.20000310.0341. 
CRWMS M&O 2000z. Features, Events, and Processes in SZ Flow and Transport. NEP-PAInput 
Transmittal 00046.T. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.20000310.0342. 
CRWMS M&O 2000aa. Subsurface Facility System Description Document. SDD-SFS-SE- 
000001. Volume I. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.20000221.0712. 
CRWMS M&O 2000bb. Mountain-Scale Coupled Processes (TH) Models. MDL-NBS-HS- 
000007 REV 00. Las Vegas, Nevada: CRWMS M&O. URN-0062. 
Davies, J.B. and Archambeau, C.B. 1997. "Geohydrological Models and Earthquake Effects at 
Yucca Mountain, Nevada." Environmental Geology, 32 (1), 23-35. New York, New York: 
Springer International. TIC: 237118. 
DOE (U.S. Department of Energy) 2000. Quality Assurance Requirements and Description. 
DOE/RW-0333P, Rev. 9. Washington, D.C.: U.S. Department of Energy, Office of Civilian 
Radioactive Waste Management. ACC: MOL.19991028.0012. 
DOE 1998. Viability Assessment of a Repository at Yucca Mountain. DOE/RW-0508. Volume 
one. Washington, D.C.: U.S. Government Printing Office. ACC: MOL.19981007.0028. 
Dyer, J.R. 1999. "Revised Interim Guidance Pending Issuance of New U.S. Nuclear Regulatory 
Commission (NRC) Regulations (Revision 01, July 22, 1999), for Yucca Mountain, Nevada." 
Letter from J.R. Dyer (DOE) to Dr. D.R. Wilkins (CRWMS M&O), September 3, 1999, 
OL&RC:SB-1714, with enclosure, "Interim Guidance Pending Issuance of New NRC 
Regulations for Yucca Mountain (Revision 01)." ACC: MOL.19990910.0079. 
Forester, R.M.; Bradbury, J.P.; Carter, C.; Elvidge-Tuma, A.B.; Hemphill, M.L.; Lundstrom, 
S.C.; Mahan, S.A.; Marshall, B.D.; Neymark, L.A.; Paces, J.B.; Sharpe, S.E.; Whelan, J.F.; and

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Wigand, P.E. 1999. The Climatic and Hydrologic History of Southern Nevada During the Late 
Quaternary. Open-File Report 98-635. Denver, Colorado: U.S. Geological Survey. TIC: 245717. 
Keller, Edward A., 1992. Environmental Geology. Sixth Edition. New York, New York: 
Macmillan Publishing Company. Library Tracking Number-L1314. 
Muir-Wood, R. and King, G.C.P. 1993. "Hydrological Signatures of Earthquake Strain." Journal 
of Geophysical Research, 98 (B12), 22035-22068. Washington, D.C.: American Geophysical 
Union. TIC: 246222. 
Philip, J.R., Knight, J.H., Waechter, R. T. 1989. "Unsaturated Seepage And Subterranean Holes: 
Conspectus, And Exclusion Problem For Circular Cylindrical Cavities." Water Resources 
Research, 25, 16-28. Washington, D.C.: American Geophysical Union. TIC: 239117. 
Stock, J.M. and Healy, J.H. 1988. "Stress Field at Yucca Mountain, Nevada." Geologic and 
Hydrologic Investigations of a Potential Nuclear Waste Disposal Site at Yucca Mountain, 
Southern Nevada, Carr, M.D. and Yount, J.C., eds. Bulletin 1790, 87-93. Washington, D.C.: 
U.S. Geological Survey. TIC: 233231. 
Stock, J.M.; Healy, J.H.; Hickman, S.H.; and Zoback, M.D. 1985. "Hydraulic Fracturing Stress 
Measurements at Yucca Mountain, Nevada, and Relationship to the Regional Stress Field." 
Journal of Geophysical Research, 90 (B10), 8691-8706. Washington, D.C.: American 
Geophysical Union. TIC: 219009. 
Szymanski, J.S. 1989. Conceptual Considerations of the Yucca Mountain Groundwater System 
with Special Emphasis on the Adequacy of this System to Accommodate a High-Level Nuclear 
Waste Repository, Two Volumes. Las Vegas, Nevada: U.S. Department of Energy. ACC: 
NNA.19890831.0152. 
Taylor, E.M. 1986. Impact of Time and Climate on Quaternary Soils in the Yucca Mountain 
Area of the Nevada Test Site. Master's thesis. Lakewood, Colorado: University of Colorado. TIC: 
218287. 
USGS (U.S. Geological Survey) 2000a. Future Climate Analysis. ANL-NBS-GS-000008 REV 
00. Denver, Colorado: U.S. Geological Survey URN-0004. 
YMP (Yucca Mountain Site Characterization Project) 1998. Q-List. YMP/90-55Q, Rev. 5. Las 
Vegas, Nevada: Yucca Mountain Site Characterization Office. ACC: MOL.19980513.0132. 
YMP (Yucca Mountain Project) 1993. Evaluation of the Potentially Adverse Condition 
Evidence of Extreme Erosion During the Quaternary Period at Yucca Mountain, Nevada. 
Topical Report YMP/92-41-TPR. Las Vegas, Nevada: Yucca Mountain Site Characterization 
Office. ACC: NNA.19930316.0208.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 76 of 77 March 2000 
PROCEDURES 
QAP-2-0, Conduct of Activities, Rev 5, ICN 1, 11/9/99. MOL.19991109.0221 
QAP-2-3, Classification of Permanent Items, Rev 10, 5/26/99. MOL.19990316.0006 
AP-3.10Q, Analyses and Models, Rev 2, ICN 0, 2/25/00. MOL.20000217.0246. 
AP-SI.1Q, Software Management, Rev 2 ICN 4, 2/24/00. MOL.20000223.0508. 
SOFTWARE 
Software Routine: ptn_v1.f V1 
Software Routine: perch_ele.f V1 
Software Routine: pflux_rep.f V1 
SOURCE DATA 
MO9907YMP99025.001. YMP-99-025.01, List of Boreholes. Submittal date: 7/19/1999. 
SN9907T0872799.001. Heat Decay Data and Repository Footprint for Thermal-Hydrologic and 
Conduction-Only Models for TSPA-SR (Total System Performance Assessment-Site 
Recommendation). Submittal Date: 7/27/99. 
LB990701233129.001. 3-D UZ Model Grids for Calculation of Flow Fields for PA for AMR 
U0000, Development of Numerical Grids for UZ Flow and Transport Modeling. Submittal 
Date: 9/24/99. 
LB990801233129.001. TSPA Grid Flow Simulations for AMR U0050, UZ Flow Models and 
Submodels. Submittal Date: 11/29/99. 
LB990801233129.002. TSPA Grid Flow Simulations for AMR U0050, UZ Flow Models and 
Submodels. Submittal Date: 11/29/99. 
LB990801233129.003. TSPA Grid Flow Simulations for AMR U0050, UZ Flow Models and 
Submodels. Submittal Date: 11/29/99. 
LB990801233129.004. TSPA Grid Flow Simulations for AMR U0050, UZ Flow Models and 
Submodels. Submittal Date: 11/29/99. 
LB990801233129.005. TSPA Grid Flow Simulations for AMR U0050, UZ Flow Models and 
Submodels. Submittal Date: 11/29/99. 
LB990801233129.006. TSPA Grid Flow Simulations for AMR U0050, UZ Flow Models and 
Submodels. Submittal Date: 11/29/99. 
LB990801233129.007. TSPA Grid Flow Simulations for AMR U0050, UZ Flow Models and 
Submodels. Submittal Date: 11/29/99.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 77 of 77 March 2000 
LB990801233129.008. TSPA Grid Flow Simulations for AMR U0050, UZ Flow Models and 
Submodels. Submittal Date: 11/29/99. 
LB990801233129.009. TSPA Grid Flow Simulations for AMR U0050, UZ Flow Models and 
Submodels. Submittal Date: 11/29/99. 
LB990801233129.010. TSPA Grid Flow Simulations for AMR U0050, UZ Flow Models and 
Submodels. Submittal Date: 11/29/99. 
LB990801233129.011. TSPA Grid Flow Simulations for AMR U0050, UZ Flow Models and 
Submodels. Submittal Date: 11/29/99. 
LB990801233129.012. TSPA Grid Flow Simulations for AMR U0050, UZ Flow Models and 
Submodels. Submittal Date: 11/29/99.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-1 March 2000 
ATTACHMENT I 
INCLUDED FEPS DESCRIPTIONS

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-2 March 2000 
PRIMARY YMP FEP NUMBER: 1.3.01.00.00 
FEP NAME: Climate Change, Global 
ORIGINATOR FEP DESCRIPTION: Global climate change refers to FEPs related to the possible future, 
and evidence for past, long term change of global climate. This is distinct from resulting changes that may 
occur at specific locations according to their regional setting and also climate fluctuations. 
YMP PRIMARY FEP DESCRIPTION: Climate change may affect the long-term performance of the 
repository. This includes the effects of long-term change in global climate (e.g., glacial/interglacial cycles) and 
shorter-term change in regional and local climate. Climate is typically characterized by temporal variations 
in precipitation and temperature. 
SECONDARY YMP FEP NUMBER: 1.3.01.00.01 
FEP NAME: Climate change 
ORIGINATOR FEP DESCRIPTION: The current climate may change to wetter, drier, warmer, cooler and/or 
permafrost conditions, affecting flow properties of the geosphere (including recharge volumes). 
SECONDARY YMP FEP NUMBER: 1.3.01.00.02 
FEP NAME: No ice age 
ORIGINATOR FEP DESCRIPTION: This is a variation of ice age (not a specific feature, event or process on 
the merged list). However, no ice age puts special demands on how to treat the biosphere not to be confused with the 
base case scenario which assumes a steady biosphere. 
SECONDARY YMP FEP NUMBER: 1.3.01.00.03 
FEP NAME: Solar insolation 
ORIGINATOR FEP DESCRIPTION: None 
SECONDARY YMP FEP NUMBER: 1.3.01.00.04 
FEP NAME: No ice age 
ORIGINATOR FEP DESCRIPTION: None 
SECONDARY YMP FEP NUMBER: 1.3.01.00.05 
FEP NAME: Climate change: natural 
ORIGINATOR FEP DESCRIPTION: Natural climate changes associated with Milankovitch cycles (external 
forcing processes) and leading to glacial/interglacial cycling. Natural climate change will have a direct effect on the 
biosphere in terms of ecology, and will indirectly affect the far-field by changing hydrogeological boundary 
conditions and, thus, influencing radionuclide transport. 
SECONDARY YMP FEP NUMBER: 1.3.01.00.06 
FEP NAME: Exit from glacial/interglacial cycling 
ORIGINATOR FEP DESCRIPTION: Exit from individual glacial periods will cause large volumes of surface 
water to accumulate as some glaciers melt. Melt water, and its rate of production, have an important effect on 
surface environments, groundwater fluxes and flow directions.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-3 March 2000 
SECONDARY YMP FEP NUMBER: 1.3.01.00.07 
FEP NAME: Exit from glacial/interglacial cycling 
ORIGINATOR FEP DESCRIPTION: A lengthening of individual glaciations or repeated glaciations may 
more rapidly exhume the repository. 
SECONDARY YMP FEP NUMBER: 1.3.01.00.08 
FEP NAME: Climatological (effects) 
ORIGINATOR FEP DESCRIPTION: None 
SECONDARY YMP FEP NUMBER: 1.3.01.00.09 
FEP NAME: Climate change 
ORIGINATOR FEP DESCRIPTION: There could be massive climate changes on the Shield due to 
anthropogenic and natural causes. Here the focus is on natural causes and in particular the occurrence of further 
continental glaciations. 
SECONDARY YMP FEP NUMBER: 1.3.01.00.10 
FEP NAME: Present-day climatic conditions 
ORIGINATOR FEP DESCRIPTION: The present-day climate of northern Switzerland is described as cool 
and is representative of interglacial conditions. 
SECONDARY YMP FEP NUMBER: 1.3.01.00.11 
FEP NAME: Seasonality of climate 
ORIGINATOR FEP DESCRIPTION: The degree of seasonality of climate is one factor that distinguishes the 
warm, seasonal humid climate from the warm equable humid climate. In the seasonal climate, marked seasonal 
variations in precipitation, run-off, erosion and groundwater recharge occur. In the equable climate more uniform 
conditions prevail. 
SECONDARY YMP FEP NUMBER: 1.3.01.00.12 
FEP NAME: Future climatic conditions 
ORIGINATOR FEP DESCRIPTION: Paleo-evidence indicates that climatic conditions in northern 
Switzerland have varied greatly in the past. ... Climatic change is to be expected over the timescales relevant to 
repository performance as a result of natural processes and human activities e.g. greenhouse effect. 
SECONDARY YMP FEP NUMBER: 1.3.01.00.13 
FEP NAME: Warmer climate - arid 
ORIGINATOR FEP DESCRIPTION: An arid climate is characterized by high mean annual temperatures, low 
mean annual rainfall with episodic precipitation; very low effective moisture; through-flowing major rivers (e.g., 
Rhine), with reduced run-off. etc. 
SECONDARY YMP FEP NUMBER: 1.3.01.00.14 
FEP NAME: Warmer climate - seasonal humid 
ORIGINATOR FEP DESCRIPTION: The climate could become significantly warmer than the present day 
exhibiting a marked seasonality between warm, humid, rainy seasons and cool, dry seasons (monsoon-like). 
Evapotranspiration is moderate and there is moderate effective moisture. Streams are perennial with marked 
seasonal variations is run-off. Vegetation cover is moderate. The onset of the wet season is associated with the 
maximum erosion (both fluvial down cutting and denudation). Such a climate is possible if the greenhouse effect 
was dominant and glaciation ended.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-4 March 2000 
SECONDARY YMP FEP NUMBER: 1.3.01.00.15 
FEP NAME: Warmer climate - equable humid 
ORIGINATOR FEP DESCRIPTION: This climate state is characterized by high temperatures, precipitation 
and moderate evapotranspiration with minor seasonality. This results in high effective moisture, and a well defined 
network of perennial streams with high run-off. Vegetation cover is complete and continuous. Such a climate may 
occur if the greenhouse effect becomes significant and glaciation ends. 
SECONDARY YMP FEP NUMBER: 1.3.01.00.16 
FEP NAME: Climate change (effects on repository) 
ORIGINATOR FEP DESCRIPTION: Changes to the current climate may affect the performance of the vault. 
For example, increased or decreased rates of meteoric precipitation may affect the volume and rate of groundwater 
flow past the disposal vault. 
SECONDARY YMP FEP NUMBER: 1.3.01.00.17 
FEP NAME: Global effects 
ORIGINATOR FEP DESCRIPTION: The vault behavior might be modified by global effects such as 
movement of molten material, climate change, greenhouse warming, drought and flooding. 
SECONDARY YMP FEP NUMBER: 1.3.01.00.18 
FEP NAME: Climate (meteorology) 
ORIGINATOR FEP DESCRIPTION: A wide variety of climatic factors, such as temperature, precipitation 
and wind speed, can directly or indirectly influence the behavior and transport of contaminants in the environment. 
For example, temperature influences heating fuel needs, which in turn may influence radionuclide concentration in 
indoor air and the inhalation dose to humans. Etc 
SECONDARY YMP FEP NUMBER: 1.3.01.00.19 
FEP NAME: Seasons (meteorology) 
ORIGINATOR FEP DESCRIPTION: Seasons on the Shield affect many aspects of the natural and human 
environments. Because of temperature changes that lead to freezing, photosynthesis, which is at the bottom of most 
food webs, comes to a virtual standstill during the winter. etc. 
SECONDARY YMP FEP NUMBER: 1.3.01.00.20 
FEP NAME: Temperature (meteorology) 
ORIGINATOR FEP DESCRIPTION: Temperatures at the WIPP site are moderate with annual temperature of 
about 63 F. Temperature is an important control on the amount of recharge that reaches the groundwater system and 
is accounted for in performance assessment calculations by use of a sampled parameter for scaling flow velocity in 
the Culebra. 
SECONDARY YMP FEP NUMBER: 1.3.01.00.21 
FEP NAME: Climate change (meteorology) 
ORIGINATOR FEP DESCRIPTION: Climate changes are instigated by changes in the earth's orbit, which 
affect the amount of insolation, and by feedback mechanisms within the atmosphere and hydrosphere.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-5 March 2000 
PRIMARY YMP FEP NUMBER: 1.3.07.02.00 
FEP NAME: Water table rise 
ORIGINATOR FEP DESCRIPTION: Regionally higher water tables create discharge points closer to the 
repository, reducing the distance to the accessible environment. The rise in the regional water table floods the 
repository. 
YMP PRIMARY FEP DESCRIPTION: Climate change could produce increased infiltration, leading to a 
rise in the regional water table, possibly affecting the release and exposure pathways from the repository. A 
regionally higher water table and change in flow patterns might move discharge points closer to the 
repository, or flood the repository. 
SECONDARY YMP FEP NUMBER: 1.3.07.02.01 
FEP NAME: Short circuit of a flow barrier in the saturated zone because of a water table rise 
ORIGINATOR FEP DESCRIPTION: A higher water table short-circuits a flow barrier in the saturated zone, 
changing the pattern of flow. 
PRIMARY YMP FEP NUMBER: 2.1.08.01.00 
FEP NAME: Increased unsaturated water flux at the repository 
ORIGINATOR FEP DESCRIPTION: An increase in infiltration due to climate change at the repository 
site increases the unsaturated flux through the repository. 
YMP PRIMARY FEP DESCRIPTION: An increase in the unsaturated water flux at the repository affects 
thermal, hydrologic, chemical, and mechanical behavior of the system. Extremely rapid influx could reduce 
temperatures below the boiling point during part or all of the thermal period. Increases in flux could result 
from climate change, but the cause of the increase is not an essential part of the FEP. 
SECONDARY YMP FEP NUMBER: 2.1.08.01.01 
FEP NAME: Waste container is thermally quenched by rapid influx of water 
ORIGINATOR FEP DESCRIPTION: The local influx of water is sufficient to quench (reduce the surface 
temperature below vaporization) the waste containers it surrounds. 
PRIMARY YMP FEP NUMBER: 2.1.08.02.00 
FEP NAME: Enhanced influx (Philip's drip) 
ORIGINATOR FEP DESCRIPTION: Philip's drip is a mechanism for focusing unsaturated flow to an 
underground opening and producing local saturation. 
YMP PRIMARY FEP DESCRIPTION: An opening in unsaturated rock alters the hydraulic potential, 
affecting local saturation around the opening and redirecting flow. Some of the flow is directed to the opening 
where it is available to seep into the opening. 
PRIMARY YMP FEP NUMBER: 2.2.03.01.00 
FEP NAME: Stratigraphy 
ORIGINATOR FEP DESCRIPTION: Stratigraphic information (thickness and lateral extent) is 
important input to the performance assessment. etc. 
YMP PRIMARY FEP DESCRIPTION: Stratigraphic information is necessary information for the 
performance assessment. This information should include identification of the relevant rock units, soils and 
alluvium, and their thicknesses, lateral extents, and relationships to each other. Major discontinuities should 
be identified.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-6 March 2000 
SECONDARY YMP FEP NUMBER: 2.2.03.01.01 
FEP NAME: Mesozoic sedimentary cover 
ORIGINATOR FEP DESCRIPTION: A Mesozoic sedimentary cover overlies, in part, the crystalline 
basement of Northern Switzerland, as well as the Permo-Carboniferous Trough (PCT) of Northern Switzerland. The 
Mesozoic cover consists of a heterogeneous sequence of strata, of variable thickness, that are subhorizontal and 
relatively undisturbed tectonically. etc. 
SECONDARY YMP FEP NUMBER: 2.2.03.01.02 
FEP NAME: Permo-Carboniferous Trough 
ORIGINATOR FEP DESCRIPTION: During the Variscan orogeny, the crystalline basement underwent 
extensive deformation. A graben structure, the Permo-Carboniferous Trough of Northern Switzerland, formed 
during the late stage of this orogeny(around 315-245 million years ago). Etc. Re: SZ flow system. 
SECONDARY YMP FEP NUMBER: 2.2.03.01.03 
FEP NAME: Brine reservoirs 
ORIGINATOR FEP DESCRIPTION: Units of interest to the WIPP project below the Salado are the Bell 
Canyon and the Castile. These units have quite different hydrologic characteristics. In part of the area around WIPP, 
the Castile has been significantly deformed and there are pressurized brines associated with the deformed areas. 
PRIMARY YMP FEP NUMBER: 2.2.03.02.00 
FEP NAME: Rock properties of host rock and other units 
ORIGINATOR FEP DESCRIPTION: Expected features of the rock that should be modeled include 
porosity, tortuosity, permeability, active (open) fracture joints or zones, inhomogeneities and structures such 
as layers or zones of different rock. etc. 
YMP PRIMARY FEP DESCRIPTION: Physical properties such as porosity and permeability of the 
relevant rock units, soils, and alluvium are necessary for the performance assessment. Possible 
heterogeneities in these properties should be considered. 
SECONDARY YMP FEP NUMBER: 2.2.03.02.01 
FEP NAME: Rock heterogeneity (host rock) 
ORIGINATOR FEP DESCRIPTION: None 
SECONDARY YMP FEP NUMBER: 2.2.03.02.02 
FEP NAME: LPD effective hydraulic properties 
ORIGINATOR FEP DESCRIPTION: The crystalline low permeability domain (LPD) consists of volume(s) 
of crystalline rock, generally at depths greater than 400-600 m below the upper surface of the crystalline basement, 
whose average effective hydraulic conductivity is small (generally less than 10-10m/s). 
SECONDARY YMP FEP NUMBER: 2.2.03.02.03 
FEP NAME: MWCF effective hydraulic properties 
ORIGINATOR FEP DESCRIPTION: The crystalline basement of Areas West (LPD and HPD) and East is 
intersected to below repository depth by major, subvertical regional faults of first and second order. ... Some of these 
faults may be water-conducting (major water-conducting faults MWCF), with a higher hydraulic conductivity than 
the LPD. etc. 
SECONDARY YMP FEP NUMBER: 2.2.03.02.04 
FEP NAME: HPD effective hydraulic properties

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-7 March 2000 
ORIGINATOR FEP DESCRIPTION: The hydraulic properties of the crystalline basement are controlled by 
the properties of the small-scale water-conducting features which dissect it. In both Area West and Area East, the 
transmissivity and density of these features, and therefore of the hydraulic conductivity of the rock through which 
they pass, undergoes an abrupt decrease at depths greater than 400-600 m below the upper surface of the crystalline 
basement. etc. 
SECONDARY YMP FEP NUMBER: 2.2.03.02.05 
FEP NAME: Properties of far-field rock 
ORIGINATOR FEP DESCRIPTION: Refers to the hydrological, mineralogical, mechanical, thermal and gas 
transport properties of the far-field rock which are of importance to radionuclide transport in the rock. Due to 
various processes and events, the properties may change with time. 
PRIMARY YMP FEP NUMBER: 2.2.07.01.00 
FEP NAME: Locally saturated flow at bedrock/alluvium contact 
ORIGINATOR FEP DESCRIPTION: In washes in arid areas, infiltration can descend to the 
alluvium/bedrock interface and then proceed down the wash at that interface as a saturated flow system 
distant from the surface and distinct from the local water table. 
YMP PRIMARY FEP DESCRIPTION: In washes in arid areas, infiltration can descend to the 
alluvium/bedrock interface and then proceed down the wash at that interface as a saturated flow system 
distant from the surface and distinct from the local water table. 
PRIMARY YMP FEP NUMBER: 2.2.07.02.00 
FEP NAME: Unsaturated groundwater flow in geosphere 
ORIGINATOR FEP DESCRIPTION: The units above the Rustler Formation at the WIPP site are 
predominantly unsaturated. There was no inflow of water from the Dewey Lake into the WIPP shafts after 
they were completed and prior to their lining, indicating unsaturated conditions or low transmissivity. etc. 
YMP PRIMARY FEP DESCRIPTION: Groundwater flow occurs in unsaturated rocks in most locations 
above the water table at Yucca Mountain, including at the location of the repository. See other FEPs in this 
section for discussions of specific issues related to unsaturated flow. See FEPs 2.2.07.03.00 (capillary rise), 
2.2.07.04.00 (focussing of unsaturated flow), 2.2.07.05.00 (effects of episodic infiltration), 2.2.07.07 (perched 
water), 2.2.07.08.00 (fracture flow), 2.2.07.09.00 (matrix imbibition), 2.2.07.10.00 (condensation zone forms), 
2.2.07.11.00 (return flow from condensation zone), and 2.2.10.10.00 (bouyant flow / heat pipes). 
SECONDARY YMP FEP NUMBER: 2.2.07.02.01 
FEP NAME: Unsaturated rock 
ORIGINATOR FEP DESCRIPTION: Portions of the geosphere may be naturally unsaturated or become 
unsaturated due to dewatering during construction of the vault. Consequently rock temperatures may rise and an 
unsaturated transport may be important. 
SECONDARY YMP FEP NUMBER: 2.2.07.02.02 
FEP NAME: Soil depth 
ORIGINATOR FEP DESCRIPTION: Soil depth refers to the distance between the soil surface down to the 
water table. ... Contaminants may move up and down the soil profile through capillary rise and leaching.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-8 March 2000 
PRIMARY YMP FEP NUMBER: 2.2.07.03.00 
FEP NAME: Capillary rise 
ORIGINATOR FEP DESCRIPTION: Capillary rise involves the drawing up of soil water, above the 
water table, in continuous pores of the soil until the suction gradient is balanced by the gravitational pull 
downward. 
YMP PRIMARY FEP DESCRIPTION: Capillary rise involves the drawing up of water, above the water 
table or above locally saturated zones, in continuous pores of the unsaturated zone until the suction gradient 
is balanced by the gravitational pull downward. Capillary rise may provide a mechanism for radionuclides to 
reach the surface environment in locations where the water table is shallow. 
SECONDARY YMP FEP NUMBER: 2.2.07.03.01 
FEP NAME: Capillary rise (near surface hydrology) 
ORIGINATOR FEP DESCRIPTION: Capillary rise is the process by which solutes may move upwards 
through the soil profile from the water table (in the aquifer), under the following conditions:(1) Evapotranspiration 
(during a part of the year) exceeds precipitation; (2) the storage capacity of the soil is insufficient to match 
Evapotranspiration minus precipitation;(3) the soil texture is sufficiently fine for capillaries to be filled with water, 
(4) the water table is sufficiently near to the soil surface for the existence of continuous capillary water between the 
aquifer and surface. 
PRIMARY YMP FEP NUMBER: 2.2.07.04.00 
FEP NAME: Focusing of unsaturated flow (fingers, weeps) 
ORIGINATOR FEP DESCRIPTION: The natural variation of hydrologic properties produces 
heterogeneities and local saturation which feeds locally saturated flow. That is, a uniform distribution of 
infiltration breaks up into localized flow fingers which feed fractures. Or, unsaturated flow reaches a flow 
barrier (a zone of reduced permeability) where the water accumulates or perches and continues as a 
saturated plume. 
YMP PRIMARY FEP DESCRIPTION: Unsaturated flow can differentiate into zones of greater and lower 
saturation (fingers) that may persist as preferential flow paths. Heterogeneities in rock properties, including 
fractures and faults, may contribute to focussing. Focussed flow may become locally saturated. 
SECONDARY YMP FEP NUMBER: 2.2.07.04.01 
FEP NAME: Effects of preferential flow paths 
ORIGINATOR FEP DESCRIPTION: The hydrogeologic properties of the Culebra are spatially variable. This 
variability, including the effects of preferential pathways, is accounted for in performance assessment calculations in 
the estimates of transmissivity and aquifer thickness. 
SECONDARY YMP FEP NUMBER: 2.2.07.04.02 
FEP NAME: Seeps and weeps form as a locally saturated flow system 
ORIGINATOR FEP DESCRIPTION: Infiltration or condensate forms fingers which persist as locally 
saturated flow either through the matrix or through any connected set of fractures the fingers reach. 
SECONDARY YMP FEP NUMBER: 2.2.07.04.03 
FEP NAME: Fault control of fluid entrance to and movement away from the repository 
ORIGINATOR FEP DESCRIPTION: Faults in the UZ act as conduits for fluids to move into the subsurface 
to interact with the repository and as conduits for fluids to leave the vicinity of the repository and be conducted to 
the SZ.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-9 March 2000 
SECONDARY YMP FEP NUMBER: 2.2.07.04.04 
FEP NAME: Fingering - contaminant transport in fingers in UZ 
ORIGINATOR FEP DESCRIPTION: Fingering is the flow mechanism in the unsaturated zone whereby long 
fingers or zones of higher saturation persist in fields of less saturated rock. These flow fingers are able to transport 
contaminants. 
PRIMARY YMP FEP NUMBER: 2.2.07.08.00 
FEP NAME: Fracture flow in the unsaturated zone 
ORIGINATOR FEP DESCRIPTION: Fractures act as conduits for fluids to move into the subsurface to 
interact with the repository and as conduits for fluids to leave the vicinity of the repository and be conducted 
to the SZ. 
YMP PRIMARY FEP DESCRIPTION: Fractures or other analogous channels act as conduits for fluids to 
move into the subsurface to interact with the repository and as conduits for fluids to leave the vicinity of the 
repository and be conducted to the SZ. 
SECONDARY YMP FEP NUMBER: 2.2.07.08.01 
FEP NAME: Fracture flow (in geosphere) 
ORIGINATOR FEP DESCRIPTION: Flow in the Culebra occurs within fractures, within vugs where they are 
connected by fractures, and to some extent within interparticle porosity where the porosity (and permeability) is 
high, such as chalky lenses. etc. 
SECONDARY YMP FEP NUMBER: 2.2.07.08.02 
FEP NAME: Extreme channel flow of oxidants and nuclides (in geosphere) 
ORIGINATOR FEP DESCRIPTION: The water does not flow over the whole fracture plane. This fact is 
often noted by "channeling". (A lengthy discussion of what channeling is and how it might affect fracture transport 
follows.) 
PRIMARY YMP FEP NUMBER: 2.2.07.09.00 
FEP NAME: Matrix imbibition in the unsaturated zone 
ORIGINATOR FEP DESCRIPTION: Flow down fractures in the phreatic zone is imbibed into the 
surrounding rock matrix. 
YMP PRIMARY FEP DESCRIPTION: Water flowing in fractures or other channels in the unsaturated 
zone is imbibed into the surrounding rock matrix. This may occur during steady flow, episodic flow, or into 
matrix pores that have been dried out during the thermal period. 
SECONDARY YMP FEP NUMBER: 2.2.07.09.01 
FEP NAME: Resaturation due to matrix imbibition of episodic fracture flow 
ORIGINATOR FEP DESCRIPTION: Episodic fracture flow, of infiltrating waters, is imbibed by the matrix 
which was dried out (reduced saturation) during the thermal period.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-10 March 2000 
PRIMARY YMP FEP NUMBER: 2.2.08.04.00 
FEP NAME: Redissolution of Precipitates Directs More Corrosive Fluids to Containers 
ORIGINATOR FEP DESCRIPTION: Redissolution of precipitates which have plugged pores as a result 
of evaporation of ground water in the hot zone, produces a pulse of fluid reaching the waste containers when 
gravity-driven flow resumes, which is more corrosive than the original fluid in the rock. 
YMP PRIMARY FEP DESCRIPTION: Redissolution of precipitates which have plugged pores as a result 
of evaporation of ground water in the hot zone, produces a pulse of fluid reaching the waste containers when 
gravity-driven flow resumes, which is more corrosive than the original fluid in the rock. See also FEP 
2.2.07.11.00 for a discussion of return flow from condensation cap. 
SECONDARY YMP FEP NUMBER: None 
FEP NAME: None 
ORIGINATOR FEP DESCRIPTION: None. 
PRIMARY YMP FEP NUMBER: 2.2.08.08.00 
FEP NAME: Matrix diffusion in geosphere 
ORIGINATOR FEP DESCRIPTION: Matrix diffusion is the process by which nuclides and other species 
in the water flowing in the rock fissures migrates into the porous rock by diffusion. Matrix diffusion is a very 
efficient retarding mechanism, especially for strongly sorbed radionuclides due to the increase in rock surface 
accessible to sorption. 
YMP PRIMARY FEP DESCRIPTION: Matrix diffusion is the process by which radionuclides and other 
species transported by advective flow in fractures or other pathways move into the matrix of the porous rock 
by diffusion. Matrix diffusion can be a very efficient retarding mechanism, especially for strongly sorbed 
radionuclides due to the increase in rock surface accessible to sorption. 
SECONDARY YMP FEP NUMBER: 2.2.08.08.01 
FEP NAME: Matrix diffusion (water transport) 
ORIGINATOR FEP DESCRIPTION: Matrix diffusion is the process by which nuclides and other species in 
the water flowing in the rock fissures migrates into the porous rock by diffusion. Matrix diffusion is a very efficient 
retarding mechanism, especially for strongly sorbed radionuclides due to the increase in rock surface accessible to 
sorption. 
SECONDARY YMP FEP NUMBER: 2.2.08.08.02 
FEP NAME: Matrix diffusion (water transport) 
ORIGINATOR FEP DESCRIPTION: Matrix diffusion is where movement of material is transverse to the 
direction of advection within a fracture and into the surrounding rock matrix. 
SECONDARY YMP FEP NUMBER: 2.2.08.08.03 
FEP NAME: Matrix diffusion (water transport) 
ORIGINATOR FEP DESCRIPTION: Matrix diffusion is the process by which nuclides and other species in 
the water flowing in the rock fissures migrates into the porous rock by diffusion. Matrix diffusion is a very efficient 
retarding mechanism, especially for strongly sorbed radionuclides due to the increase in rock surface accessible to 
sorption. 
SECONDARY YMP FEP NUMBER: 2.2.08.08.04 
FEP NAME: Matrix diffusion (water transport)

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-11 March 2000 
ORIGINATOR FEP DESCRIPTION: Contaminants may diffuse into surrounding rock from contaminated 
water in a fracture zone or from contaminated rock into a nearby fracture zone, due to matrix diffusion. 
SECONDARY YMP FEP NUMBER: 2.2.08.08.05 
FEP NAME: Matrix diffusion (water transport) 
ORIGINATOR FEP DESCRIPTION: None 
SECONDARY YMP FEP NUMBER: 2.2.08.08.06 
FEP NAME: Matrix diffusion (water transport) 
ORIGINATOR FEP DESCRIPTION: Radionuclides can migrate from the flow porosity (i.e. open channels of 
small-scale water-conducting features) into the static water of pores of the adjacent wallrock by molecular diffusion. 
This process is known as matrix diffusion. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.08.07 
FEP NAME: Matrix diffusion (water transport) 
ORIGINATOR FEP DESCRIPTION: Radionuclides can migrate from the flow porosity (i.e. open channels of 
small-scale water-conducting features) into the static water of pores of the adjacent wallrock by molecular diffusion. 
This process is known as matrix diffusion. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.08.08 
FEP NAME: Matrix diffusion (water transport) 
ORIGINATOR FEP DESCRIPTION: Matrix diffusion is the process by which nuclides in the water flowing 
in rock fissures migrates into the porous rock by diffusion. It is governed by the characteristics of fracture fillings 
and the rock mass (porosity and mineralogy). 
PRIMARY YMP FEP NUMBER: 2.2.08.09.00 
FEP NAME: Sorption in UZ and SZ 
ORIGINATOR FEP DESCRIPTION: Sorption occurs along fractures and in the matrix imbibing the 
carrier plume as contaminants are transported through the UZ. 
YMP PRIMARY FEP DESCRIPTION: Sorption of dissolved and colloidal radionuclides can occur on the 
surfaces of both fractures and matrix in rock or soil along the transport path. Sorption may be reversible or 
irreversible, and it may occur as a linear or nonlinear process. Sorption kinetics and the availability of sites 
for sorption should be considered. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.01 
FEP NAME: Far-field transport: Sorption including ion-exchange 
ORIGINATOR FEP DESCRIPTION: Sorption is a general term to describe the retardation of radionuclides 
when they bind directly to solid surfaces. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.02 
FEP NAME: Far-field transport: Changes in sorptive surfaces 
ORIGINATOR FEP DESCRIPTION: Sorption to solid surfaces (in fractures and secondary porosity) will be 
controlled by the accessibility of those surfaces and their mineralogy (chemistry, structure). Over the lifetime of the 
repository, both the available area and the mineralogy of solid surfaces may change and, hence, the potential for 
sorption in the far-field will be time-dependent. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.03 
FEP NAME: Anion-exclusion General: (in geosphere)

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-12 March 2000 
ORIGINATOR FEP DESCRIPTION: Mineral surfaces are usually negatively charged in contact with water. 
Because of the negative electric field, anions are repelled from the surface. As a consequence, the movement of 
anions in clays and rock matrices are restricted to the largest pores or fractures. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.04 
FEP NAME: Soil pore water pH 
ORIGINATOR FEP DESCRIPTION: The pH of soil pore water is an important factor in determining the 
behavior and transport of contaminants in the soil because it affects sorption to soil solids. ... Decreased sorption 
means higher mobility and this may open up a variety of exposure pathways. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.05 
FEP NAME: Soil sorption 
ORIGINATOR FEP DESCRIPTION: Soil sorption refers to the process whereby contaminants adhere to or 
are taken up in soil solids and become essentially immobilized. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.06 
FEP NAME: Ion exchange in soil 
ORIGINATOR FEP DESCRIPTION: During ion exchange in the soil, contaminating radionuclides may 
become sorbed to soil materials by displacing other ions. Thus, ion exchange relates to the mobility of contaminants 
in soil as do other processes, such as chemical precipitation. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.07 
FEP NAME: Sorption (reversible and irreversible) 
ORIGINATOR FEP DESCRIPTION: Sorption is the sticking of contaminant solutes to the surfaces of the 
rock by chemical interaction. It could be reversible, allowing redissolution or irreversible, removing some of the 
contaminant from the flow field. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.08 
FEP NAME: Sorption - nonlinear 
ORIGINATOR FEP DESCRIPTION: Some chemical elements may display nonlinear characteristics for 
reasons such as chemical kinetic effects, concentration effects and the formation of precipitates, etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.09 
FEP NAME: Saturation (of sorption sites) 
ORIGINATOR FEP DESCRIPTION: The available sorption sites may be saturated by an overabundance of 
contaminants or natural competing species. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.10 
FEP NAME: Sorption (geosphere) 
ORIGINATOR FEP DESCRIPTION: Sorption of contaminants will depend on factors such as the nature of 
the contaminant, minerals involved, mineral surface area, pH,Eh, salinity and available complexing ligands. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.11 
FEP NAME: Sorption 
ORIGINATOR FEP DESCRIPTION: None 
SECONDARY YMP FEP NUMBER: 2.2.08.09.12

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-13 March 2000 
FEP NAME: Sorption 
ORIGINATOR FEP DESCRIPTION: The interaction of dissolved radionuclides with rock surfaces, 
excluding precipitation, is termed sorption. Radionuclides can sorb on the surfaces of open channels within waterconducting 
features and also on the surfaces of pores accessible by matrix diffusion (i.e. pore surfaces within 
fracture infill and wallrock). etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.13 
FEP NAME: Nonlinear sorption 
ORIGINATOR FEP DESCRIPTION: In general, the partitioning of radionuclides between sorbed and 
aqueous phases is dependent on elemental concentration (i.e. the concentration of the element of which the 
radionuclide under consideration is an isotope). Where such dependency exists, sorption is said to be nonlinear. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.14 
FEP NAME: Nonlinear sorption 
ORIGINATOR FEP DESCRIPTION: The interaction of dissolved radionuclides with rock surfaces, 
excluding precipitation, is termed sorption. Radionuclides can sorb on the surfaces of open channels within waterconducting 
features and also on the surfaces of pores accessible by matrix diffusion (i.e. pore surfaces within 
fracture infill and wallrock). etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.15 
FEP NAME: Nonlinear sorption 
ORIGINATOR FEP DESCRIPTION: In general, the partitioning of radionuclides between sorbed and 
aqueous phase is dependent on elemental concentration (i.e. the concentration of the element of which the 
radionuclide under consideration is an isotope). Where such dependency exists, sorption is said to be nonlinear. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.16 
FEP NAME: Sorption 
ORIGINATOR FEP DESCRIPTION: The interaction of dissolved radionuclides with rock surfaces, 
excluding precipitation, is termed sorption. Sorption would retard the migration of radionuclides through the HPD. 
The degree to which radionuclides sorb on pore surfaces is dependent on the elemental concentration(...) and on the 
properties of the rock-water system under consideration-in particular, the mineralogy and the groundwater 
chemistry. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.17 
FEP NAME: Radionuclide sorption 
ORIGINATOR FEP DESCRIPTION: The physio-chemical interaction of dissolved radionuclides with soils 
and sediments is termed sorption. This interaction is affected by chemical, physical and biological conditions. For 
biosphere modeling purposes, reversible equilibrium sorption is assumed. Concentration independent (linear) 
sorption is quantified by Kd values, the evaluation of which takes account of the particular environmental media. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.18 
FEP NAME: Sorption 
ORIGINATOR FEP DESCRIPTION: Sorption is the collective term for adsorption of particles (molecules, 
ions, colloids) on outer or inner surfaces of solids. The forces responsible for sorption range from "physical" 
interactions (van der Waals' forces) to the formation of chemical bonds. ... Sorption will affect the transport and 
release of sorbing radionuclides from the different repository barriers. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.19 
FEP NAME: Actinide sorption

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-14 March 2000 
ORIGINATOR FEP DESCRIPTION: Sorption may be defined as the accumulation of matter at the interface 
between a solid and an aqueous solution. Within performance assessment calculations, including those made for the 
WIPP, the use of isotherm representations of actinide sorption prevails because of their computational simplicity in 
comparison with other models. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.20 
FEP NAME: Kinetics of sorption 
ORIGINATOR FEP DESCRIPTION: The relevance to the WIPP of sorption reaction kinetics lies in their 
effects on chemical transport. Sorption of waste contaminants to static surfaces of the disposal system such as seals 
and host rocks acts to retard chemical transport. Sorption of waste contaminants to potentially mobile surfaces, such 
as colloids, however, may act to enhance chemical transport, particularly if the kinetics of contaminant desorption 
are slow or the process is irreversible (non-equilibrium). ... The potential effects of reaction kinetics in adsorption 
processes in the Culebra are encompassed in the range of Kds used. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.21 
FEP NAME: Changes in sorptive surfaces 
ORIGINATOR FEP DESCRIPTION: The geochemical speciation of the Culebra groundwaters and the 
effects of changes in sorptive surfaces are implicitly accounted for in performance assessment calculations for the 
WIPP in the ranges of Kds used. 
SECONDARY YMP FEP NUMBER: 2.2.08.09.22 
FEP NAME: Sorption - nonlinear (geosphere) 
ORIGINATOR FEP DESCRIPTION: Sorption of contaminants may show a nonlinear dependence on factors 
such as contaminant concentration. The extent of sorption along a flow path may also change in response to different 
combinations of minerals and groundwater chemistry. 
PRIMARY YMP FEP NUMBER: 2.2.08.10.00 
FEP NAME: Colloidal transport in geosphere 
ORIGINATOR FEP DESCRIPTION: Radionuclide transport may be enhanced by organic and inorganic 
colloids in the far-field, when poorly soluble radionuclides sorb onto the colloids and are subsequently 
transported by advection along fractures. Colloids may form in the far-field or may migrate into the far-field 
or the biosphere. 
YMP PRIMARY FEP DESCRIPTION: Radionuclides may be transported in groundwater in the geosphere 
as colloidal species. Types of colloids include true colloids, pseudocolloids, and microbial colloids. 
SECONDARY YMP FEP NUMBER: 2.2.08.10.01 
FEP NAME: Far-field transport: Transport of radionuclides bound to microbes 
ORIGINATOR FEP DESCRIPTION: Microbes can be considered as colloids, as they are similar in size and 
radionuclides may sorb to them and be advectively transported along fractures in the same manner as colloids. 
Microbes may, however, through biological processes, enhance the transport of radionuclides through the far-field 
over and above that expected for colloids. 
SECONDARY YMP FEP NUMBER: 2.2.08.10.02 
FEP NAME: Colloid transport occurs in a carrier plume (in geosphere) 
ORIGINATOR FEP DESCRIPTION: Radionuclides are dissolved into the carrier plume. 
SECONDARY YMP FEP NUMBER: 2.2.08.10.03 
FEP NAME: Colloids (in geosphere)

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-15 March 2000 
ORIGINATOR FEP DESCRIPTION: Colloids may be formed in the EDZ by erosion of the bentonite or 
precipitation of major elements(e.g. silica) or radionuclides due to lower solubility in the EDZ than in bentonite 
porewater. 
PRIMARY YMP FEP NUMBER: 2.2.10.03.00 
FEP NAME: Natural geothermal effects 
ORIGINATOR FEP DESCRIPTION: There can be natural geothermal flows due for example to 
variations in thermal conductivity. Also thermally induced flows can be induced by heat output from the 
repository. 
YMP PRIMARY FEP DESCRIPTION: The existing geothermal gradient, and spatial or temporal 
variability in that gradient, may affect groundwater flow in the unsaturated and saturated zones. 
SECONDARY YMP FEP NUMBER: 2.2.10.03.01 
FEP NAME: Natural thermal effects (in geosphere) 
ORIGINATOR FEP DESCRIPTION: None 
SECONDARY YMP FEP NUMBER: 2.2.10.03.02 
FEP NAME: Geothermal regime 
ORIGINATOR FEP DESCRIPTION: The temperature field within the crystalline basement is determined by 
(i) the large scale geological and petrophysical properties of the rock (e.g. radiogenic heat production, thermal 
conductivity) and (ii) by the hydrogeological properties of the rock (in particular, the hydraulic conductivity), etc. ... 
Temperature gradients may drive groundwater flow; this is neglected in groundwater flow modeling for Kristallin-I. 
SECONDARY YMP FEP NUMBER: 2.2.10.03.03 
FEP NAME: Geothermal regime 
ORIGINATOR FEP DESCRIPTION: The temperature field within the crystalline basement is determined by 
(i) the large scale geological and petrophysical properties of the rock (e.g. radiogenic heat production, thermal 
conductivity) and (ii) by the hydrogeological properties of the rock (in particular, the hydraulic conductivity), etc. ... 
Temperature gradients may drive groundwater flow; this is neglected in groundwater flow modeling for Kristallin-I. 
SECONDARY YMP FEP NUMBER: 2.2.10.03.04 
FEP NAME: Geothermal gradient effects 
ORIGINATOR FEP DESCRIPTION: Groundwater flow will be influenced by existing geothermal gradients; 
groundwater may tend to form convection cells. 
PRIMARY YMP FEP NUMBER: 2.2.10.10.00 
FEP NAME: Two-phase bouyant flow / heat pipes 
ORIGINATOR FEP DESCRIPTION: Heat from waste generates 2-phase buoyant flow. The vapor phase 
(water vapor) escapes from the mountain. 
YMP PRIMARY FEP DESCRIPTION: Heat from waste generates two-phase buoyant flow. The vapor 
phase (water vapor) escapes from the mountain. A heat pipe consists a system for transferring energy 
between a hot and a cold region(source and sink respectively) using the heat of vaporization and movement of 
the vapor as the transfer mechanism. Two-phase circulation continues until the heat source is too weak to 
provide thermal gradients required to drive it. Any alteration of the rock adjacent to the drift produces may 
include dissolution which maintains the permeability necessary to support the circulation (as inferred for 
some geothermal systems).

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-16 March 2000 
SECONDARY YMP FEP NUMBER: 2.2.10.10.01 
FEP NAME: Heat pipe -evolving 
ORIGINATOR FEP DESCRIPTION: A heat pipe evolves by altering the rock adjacent to the drift producing 
local dry-out, shutting off circulation and migrating further into the rock. 
SECONDARY YMP FEP NUMBER: 2.2.10.10.02 
FEP NAME: Heat pipe -continuing 
ORIGINATOR FEP DESCRIPTION: A heat pipe is "continuing" when the 2-phase circulation continues 
until the heat source is too weak to provide thermal gradients required to drive it. 
SECONDARY YMP FEP NUMBER: 2.2.10.10.03 
FEP NAME: Heat pipe formation, 2-phase system 
ORIGINATOR FEP DESCRIPTION: A heat pipe consists a system for transferring energy between a hot and 
a cold region(source and sink respectively) using the heat of vaporization and movement of the vapor as the transfer 
mechanism. 
PRIMARY YMP FEP NUMBER: 2.3.01.00.00 
FEP NAME: Topography and morphology 
ORIGINATOR FEP DESCRIPTION: Topography and morphology refers to FEPs related to a the relief 
and shape of the surface environment and its evolution. 
YMP PRIMARY FEP DESCRIPTION: This category includes FEPs related to the topography and surface 
morphology of the disposal region. Topographical features include outcrops and hills, water-filled 
depressions, wetlands, recharge areas and discharge areas. Topography, precipitation, and surficial 
permeability distribution in the system will determine the flow boundary conditions, i.e. location and amount 
of recharge and discharge in the system. 
SECONDARY YMP FEP NUMBER: 2.3.01.00.01 
FEP NAME: Topography (current) 
ORIGINATOR FEP DESCRIPTION: Present-day topographical features should be modeled, including 
outcrops and hills, water-filled depressions, wetlands, recharge areas and discharge areas. 
SECONDARY YMP FEP NUMBER: 2.3.01.00.02 
FEP NAME: Topography (future) 
ORIGINATOR FEP DESCRIPTION: Changes affecting topographical features should be modeled or 
estimated, so that subsequent effects on flow can be taken into account. 
SECONDARY YMP FEP NUMBER: 2.3.01.00.03 
FEP NAME: Terrestrial surface 
ORIGINATOR FEP DESCRIPTION: Land areas on the Shield include rocky outcrops, bare soil, grassland, 
bush and forest. Each of these types of areas has unique physical, chemical and biological properties that may 
influence the behavior and transport of contaminants. 
SECONDARY YMP FEP NUMBER: 2.3.01.00.04 
FEP NAME: Physiography 
ORIGINATOR FEP DESCRIPTION: The DOE addresses issues related to groundwater flow and 
radionuclide transport within the context of a conceptual model of how the natural hydrologic system works on a 
large scale. etc.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-17 March 2000 
SECONDARY YMP FEP NUMBER: 2.3.01.00.05 
FEP NAME: Geomorphological (processes) 
ORIGINATOR FEP DESCRIPTION: None 
SECONDARY YMP FEP NUMBER: 2.3.01.00.06 
FEP NAME: External flow boundaries (surface environment) 
ORIGINATOR FEP DESCRIPTION: Topography, climate precipitation and surficial permeability 
distribution in the system will determine the flow boundary conditions, i.e. location and amount of recharge and 
discharge in the system. 
SECONDARY YMP FEP NUMBER: 2.3.01.00.07 
FEP NAME: Changes in geometry and driving forces of the flow system 
ORIGINATOR FEP DESCRIPTION: The geometry of the groundwater flow-field in the region around a 
repository will be bounded by a variety of physical features, e.g. topographic highs or faults. Over the lifetime of the 
repository the flow-field geometry and the driving forces for flow will change as the physical boundaries are altered 
by processes such as glaciation, erosion or sea level change. etc. 
PRIMARY YMP FEP NUMBER: 2.3.11.01.00 
FEP NAME: Precipitation 
ORIGINATOR FEP DESCRIPTION: The amount of precipitation depends on climate and transports 
solutes with it as it flows downward through the soil profile or escapes as runoff. 
YMP PRIMARY FEP DESCRIPTION: Precipitation is an important control on the amount of recharge. It 
transports solutes with it as it flows downward through the subsurface or escapes as runoff. The amount of 
precipitation depends on climate. 
SECONDARY YMP FEP NUMBER: 2.3.11.01.01 
FEP NAME: Precipitation, temperature and soil water balance 
ORIGINATOR FEP DESCRIPTION: None 
SECONDARY YMP FEP NUMBER: 2.3.11.01.02 
FEP NAME: Flood (meteorology) 
ORIGINATOR FEP DESCRIPTION: The current levels of meteoric precipitation could change substantially, 
leading to much greater flows of water through the geosphere, with accompanying changes to the biosphere. 
SECONDARY YMP FEP NUMBER: 2.3.11.01.03 
FEP NAME: Extremes of precipitation, snow melt and associated flooding (meteorology) 
ORIGINATOR FEP DESCRIPTION: None 
SECONDARY YMP FEP NUMBER: 2.3.11.01.04 
FEP NAME: Precipitation (meteorology) 
ORIGINATOR FEP DESCRIPTION: Precipitation in the region of the WIPP is low (about 13 inches per 
year). Precipitation is an important control on the amount of recharge that reaches the groundwater system and is 
accounted for in performance assessment calculations by use of a sampled parameter for scaling flow in the Culebra. 
PRIMARY YMP FEP NUMBER: 2.3.11.02.00 
FEP NAME: Surface runoff and flooding

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-18 March 2000 
ORIGINATOR FEP DESCRIPTION: Precipitation which does not infiltrate the soil, but moves across 
the surface directly into a surface water body, e.g. river, is called surface runoff. It may be an important 
cause of erosion. 
YMP PRIMARY FEP DESCRIPTION: Surface runoff and evapotranspiration are components in the 
water balance, together with precipitation and infiltration. They can also be important vehicles for the 
dispersion of contaminants. Surface runoff produces erosion, and can feed washes, arroyos, and 
impoundments, where flooding may lead to increased recharge. 
SECONDARY YMP FEP NUMBER: 2.3.11.02.01 
FEP NAME: Runoff (near surface hydrology) 
ORIGINATOR FEP DESCRIPTION: Runoff refers to precipitation water that runs off laterally, at or below 
the surface, to drain into a water body. Thus, runoff is important in determining the flushing rate of surface water 
bodies (Bird et al. 1994). Runoff may also carry contaminants, scavenged from the atmosphere or leached from the 
soil, to water bodies. Runoff is therefore an important vehicle for the dispersion of contaminants. Moreover, runoff 
is an important component in the water balance which, together with precipitation, infiltration and 
evapotranspiration, determines irrigation water needs for optimal crop production. 
SECONDARY YMP FEP NUMBER: 2.3.11.02.02 
FEP NAME: Flooding (near surface hydrology) 
ORIGINATOR FEP DESCRIPTION: Short-term flooding can alter the landscape and may destroy, or help 
create, agricultural land. Flooding could be caused by intentional or accidental human actions. There could also be 
natural causes of flooding such as beavers. etc. 
SECONDARY YMP FEP NUMBER: 2.3.11.02.03 
FEP NAME: Evapotranspiration (near surface hydrology) 
ORIGINATOR FEP DESCRIPTION: Evapotranspiration depends on the climate and causes solutes to move 
upwards in the soil layers; even when the annual precipitation(P) is larger than the Evapotranspiration(ETP), ETP 
may still exceed P during part of the year etc. 
SECONDARY YMP FEP NUMBER: 2.3.11.02.04 
FEP NAME: Flooding occurs in Drill Hole Wash and increases percolation below the wash 
ORIGINATOR FEP DESCRIPTION: Flooding occurs in Drill Hole Wash, and percolation flux is 
substantially increased below the wash. Some water seeps to sealed shafts and boreholes where there are 
unexpectedly large flows down through the seal material or down through the disturbed rock around the seals. 
SECONDARY YMP FEP NUMBER: 2.3.11.02.05 
FEP NAME: Faulting at the surface produces a scarp causing an impoundment 
ORIGINATOR FEP DESCRIPTION: Faulting produces a scarp at the surface which forms an impoundment 
during periods of high precipitation. Percolation flux is substantially increased below the impoundment. 
SECONDARY YMP FEP NUMBER: 2.3.11.02.06 
FEP NAME: River flooding 
ORIGINATOR FEP DESCRIPTION: Changes in the surface environment driven by natural climate change 
are expected to occur over the next 10,000 tears. Intermittent flooding of stream channels and the formation of 
shallow lakes will occur in the WIPP region over the next 10,000 years. etc. 
PRIMARY YMP FEP NUMBER: 3.1.01.01.00 
FEP NAME: Radioactive decay and ingrowth

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-19 March 2000 
ORIGINATOR FEP DESCRIPTION: Calculation of the radioactive decay of radionuclides and the 
growth of daughter products as a consequence of that decay. The repository inventory defines initial 
quantities of radionuclides and standard decay chain theory and half-lives are used to calculate the 
radionuclide quantities at any later time. 
YMP PRIMARY FEP DESCRIPTION: Radioactive decay of the fuel in the repository changes the 
radionuclide content in the fuel with time and generates heat. Radionuclide quantities in the system at any 
time are the result of the radioactive decay and the growth of daughter products as a consequence of that 
decay. The type of radiation generated by the decay depends on the radionuclide, and the penetrating 
distance of the radiation depends on the type of radiation, its energy and the surrounding medium. 
SECONDARY YMP FEP NUMBER: 3.1.01.01.01 
FEP NAME: Radioactive decay 
ORIGINATOR FEP DESCRIPTION: Radioactive decay, including the ingrowth of progeny in decay chains, 
will affect concentrations of radionuclides and stable isotopes in the waste matrices, and in other parts of the vault. 
SECONDARY YMP FEP NUMBER: 3.1.01.01.02 
FEP NAME: Radioactive decay 
ORIGINATOR FEP DESCRIPTION: Radioactive decay, including the ingrowth of progeny, will affect the 
movement and concentrations of contaminants. Members of a radioactive decay chain may have different sorption 
and transport properties in the geosphere. 
SECONDARY YMP FEP NUMBER: 3.1.01.01.03 
FEP NAME: Radioactive decay 
ORIGINATOR FEP DESCRIPTION: Radionuclides decay and are transformed into other radionuclides or 
stable isotopes, with characteristic half-lives that can range from fractions of seconds to millions of years. During 
decay, various types of radiation are emitted that can be harmful to all organisms. etc. 
SECONDARY YMP FEP NUMBER: 3.1.01.01.04 
FEP NAME: Radioactive decay and ingrowth 
ORIGINATOR FEP DESCRIPTION: None 
SECONDARY YMP FEP NUMBER: 3.1.01.01.05 
FEP NAME: Radioactive decay 
ORIGINATOR FEP DESCRIPTION: Radionuclides decay to form products (stable or radioactive) at 
characteristic rates. Decay schemes and half-lives are relatively well established but there may be some variation in 
exact data used between different models. etc. 
SECONDARY YMP FEP NUMBER: 3.1.01.01.06 
FEP NAME: Radioactive decay 
ORIGINATOR FEP DESCRIPTION: The radioactive decay of the fuel in the repository is well known. It 
changes the initial radionuclide content in the fuel with time and generates heat. The type of radiation generated by 
the decay depends on the radionuclide, and the penetrating distance of the radiation depends on the type of radiation, 
its energy and the surrounding medium. 
SECONDARY YMP FEP NUMBER: 3.1.01.01.07 
FEP NAME: Radioactive decay of mobile nuclides

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 I-20 March 2000 
ORIGINATOR FEP DESCRIPTION: Refers to radionuclides which are released from the fuel and are 
dissolved in the water or sorbed or reprecipitated in barriers outside the fuel. These radionuclides will decay thereby 
changing the concentration and distribution in the water and in the barrier materials. 
SECONDARY YMP FEP NUMBER: 3.1.01.01.08 
FEP NAME: Radionuclide decay and ingrowth 
ORIGINATOR FEP DESCRIPTION: The PA code, NUTS, calculates the overall movement and decay of 
radionuclides in the repository and disposal system. etc. 
SECONDARY YMP FEP NUMBER: 3.1.01.01.09 
FEP NAME: Radiological events and processes 
ORIGINATOR FEP DESCRIPTION: None

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 II-1 March 2000 
ATTACHMENT II 
BOREHOLES AND REPOSITORY SEALS FEPS DESCRIPTIONS

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 II-2 March 2000 
PRIMARY YMP FEP NUMBER: 1.1.01.01.00 
FEP NAME: Open site investigation boreholes 
ORIGINATOR FEP DESCRIPTION: Boreholes that have been left open, improperly sealed or reopened 
for some reason, could modify flow and transport properties, including transport within the borehole and 
within the damaged zone surrounding the borehole. Similar effects could occur for the vaults. 
YMP PRIMARY FEP DESCRIPTION: Site investigation boreholes that have been left open, improperly 
sealed, or reopened for some reason, could modify flow and transport properties and produce enhanced 
pathways between the surface and the repository. 
SECONDARY YMP FEP NUMBER: 1.1.01.01.01 
FEP NAME: Exploratory boreholes (sealing) 
ORIGINATOR FEP DESCRIPTION: Exploratory boreholes may remain open for a time for monitoring 
purposes but are expected to be sealed eventually. Their relatively small diameters and sparse occurrence will mean 
that they are unlikely to have any long-term safety implications. 
SECONDARY YMP FEP NUMBER: 1.1.01.01.02 
FEP NAME: Investigation boreholes 
ORIGINATOR FEP DESCRIPTION: There are a large number of boreholes drilled from the surface as part 
of the site investigation program for WIPP. ... There are four WIPP investigation boreholes, however, that do 
intersect the repository horizon within the controlled area. These could potentially act as pathways to the Culebra or 
to the surface for radionuclides that migrate along the anhydrite layers a and b, MB138, and MB139. 
SECONDARY YMP FEP NUMBER: 1.1.01.01.03 
FEP NAME: Underground boreholes 
ORIGINATOR FEP DESCRIPTION: The site investigation program has involved the drilling of boreholes 
from within the excavated part of the repository. Following their use for monitoring or other purposes, these 
underground boreholes will be sealed where practical, and salt creep will also serve to consolidate the seal and close 
the boreholes. 
PRIMARY YMP FEP NUMBER: 1.1.01.02.00 
FEP NAME: Loss of integrity of borehole seals 
ORIGINATOR FEP DESCRIPTION: A number of boreholes drilled from the surface in and around the 
repository footprint during the exploration and site chacterisation phase. These boreholes will be sealed after 
use. If the seals degrade the boreholes may offer a short-circuit route to the biosphere. 
YMP PRIMARY FEP DESCRIPTION: Degradation and/or failure of seals in site investigation boreholes 
could alter the flow path between the surface and the repository and possibly create a short-circuit to the 
biosphere. 
SECONDARY YMP FEP NUMBER: 1.1.01.02.01 
FEP NAME: Investigation borehole seal failure and degradation 
ORIGINATOR FEP DESCRIPTION: None.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 II-3 March 2000 
SECONDARY YMP FEP NUMBER: 1.1.01.02.02 
FEP NAME: Borehole seal failure 
ORIGINATOR FEP DESCRIPTION: Failure of the borehole seals and grouts could modify flow and 
transport properties, including transport within the borehole and between the rocks and seals. 
PRIMARY YMP FEP NUMBER: 1.1.02.01.00 
FEP NAME: Site flooding (during construction and operation) 
ORIGINATOR FEP DESCRIPTION: None. 
YMP PRIMARY FEP DESCRIPTION: Flooding of the site during operations could introduce water into 
the underground, and could affect long-term performance. 
SECONDARY YMP FEP NUMBER: 1.1.02.01.01 
FEP NAME: Repository flooding during operation 
ORIGINATOR FEP DESCRIPTION: None. 
PRIMARY YMP FEP NUMBER: 1.1.04.01.00 
FEP NAME: Incomplete closure 
ORIGINATOR FEP DESCRIPTION: Incomplete or improper closure of the repository could lead to 
enhanced radionuclide releases to the geosphere and biosphere. Inadequate closure could result from failures 
in the repository seals or from abandonment of the repository. 
YMP PRIMARY FEP DESCRIPTION: Disintegration of society could result in incomplete closure, sealing 
and decommissioning of the disposal vault. 
SECONDARY YMP FEP NUMBER: 1.1.04.01.01 
FEP NAME: Vault closure (geosphere) 
ORIGINATOR FEP DESCRIPTION: Incomplete or improper closure of the vault could lead to significant 
changes to anticipated flow in the geosphere. 
SECONDARY YMP FEP NUMBER: 1.1.04.01.02 
FEP NAME: Non-sealed repository 
ORIGINATOR FEP DESCRIPTION: Open or partially open boreholes and shafts will enhance disruption of 
the mechanical barriers, increase the groundwater flow and produce paths from the repository with practically no 
sorption or matrix diffusion. 
SECONDARY YMP FEP NUMBER: 1.1.04.01.03 
FEP NAME: Poor closure 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 1.1.04.01.04 
FEP NAME: Abandonment of unsealed repository 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 1.1.04.01.05 
FEP NAME: Unsealed boreholes and/or shafts

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 II-4 March 2000 
ORIGINATOR FEP DESCRIPTION: This is a variant of FEP J5.02 (non-sealed repository), even if a nonsealed 
repository may include more than unsealed boreholes and shafts. Unsealed boreholes and shafts affect the 
stability of the technical barriers, the transport in the nearby rock and transport in the geosphere. 
SECONDARY YMP FEP NUMBER: 1.1.04.01.06 
FEP NAME: Operation and closure 
ORIGINATOR FEP DESCRIPTION: None. 
PRIMARY YMP FEP NUMBER: 1.1.11.00.00 
FEP NAME: Monitoring of repository 
ORIGINATOR FEP DESCRIPTION: Monitoring of repository refers to FEPs related to any monitoring 
that is carried out during operations or following closure of sections of, or the total, repository. This includes 
monitoring for operational safety and also monitoring of parameters related to the long-term safety and 
performance. 
YMP PRIMARY FEP DESCRIPTION: This category contains FEPs related to monitoring that is carried 
out during or after operations, for either operational safety or verification of long-term performance. 
Monitoring boreholes could provide enhanced pathways between the surface and the repository. 
SECONDARY YMP FEP NUMBER: 1.1.11.00.01 
FEP NAME: Monitoring and remedial activities 
ORIGINATOR FEP DESCRIPTION: Boreholes used to monitor performance could provide pathways for 
contaminant transport. Similarly some activities to remedy problems could lead to enhanced transport. 
SECONDARY YMP FEP NUMBER: 1.1.11.00.02 
FEP NAME: Postclosure monitoring 
ORIGINATOR FEP DESCRIPTION: Postclosure monitoring schemes must be designed with care. A 
monitoring well represents a short path to the biosphere and may also be used for a water supply. etc. 
SECONDARY YMP FEP NUMBER: 1.1.11.00.03 
FEP NAME: Post-closure monitoring 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 1.1.11.00.04 
FEP NAME: Postclosure monitoring 
ORIGINATOR FEP DESCRIPTION: Monitoring methods may be detrimental to the performance of the 
disposal system. Postclosure monitoring is required by 40 CFR 191.14(b) as an assurance requirement to "detect 
substantial and detrimental deviations from performance". etc. 
PRIMARY YMP FEP NUMBER: 1.4.04.02.00 
FEP NAME: Abandoned and undetected boreholes 
ORIGINATOR FEP DESCRIPTION: Future or existing boreholes affect performance. 
YMP PRIMARY FEP DESCRIPTION: Abandoned and undetected boreholes could provide pathways for 
preferential flow and, potentially, contaminant transport between any intersected zones. These flow 
connections could also result in geochemical changes in the receiving hydrologic units.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 II-5 March 2000 
SECONDARY YMP FEP NUMBER: 1.4.04.02.01 
FEP NAME: Exploratory borehole creates flow pathway 
ORIGINATOR FEP DESCRIPTION: An exploratory borehole creates a pathway for preferential flow 
through the upper nonwelded unit, and a wetter zone develops beneath in the Topopah Spring welded unit. 
SECONDARY YMP FEP NUMBER: 1.4.04.02.02 
FEP NAME: Container lies in the trace of an old borehole 
ORIGINATOR FEP DESCRIPTION: A horizontally-emplaced canister lies in the trace of an old borehole, 
which is a preferential path for water. Corrosion and transport are accelerated. 
SECONDARY YMP FEP NUMBER: 1.4.04.02.03 
FEP NAME: Waste-induced borehole flow (in waste and EBS) 
ORIGINATOR FEP DESCRIPTION: ... Abandoned boreholes could provide pathways for fluid flow and, 
potentially, contaminant transport between any intersected zones. For example, such boreholes could provide 
pathways for vertical flow between transmissive units in the Rustler, or between the Culebra and units below the 
Salado, which could affect fluid densities, flow rates, and flow directions. The exact mechanism by which waste 
contributes appears to be by being sequestered in waste panels which could function as pressure sinks and sources. 
SECONDARY YMP FEP NUMBER: 1.4.04.02.04 
FEP NAME: Flow through undetected boreholes 
ORIGINATOR FEP DESCRIPTION: Abandoned water, potash, oil, and gas exploration and production 
boreholes exist within and outside the controlled area. The DOE assumes that records of past and present drilling 
activities in New Mexico are accurate and that evidence of any preexisting boreholes would be included in these 
records. 
SECONDARY YMP FEP NUMBER: 1.4.04.02.05 
FEP NAME: Natural borehole fluid flow 
ORIGINATOR FEP DESCRIPTION: ... Abandoned boreholes could provide pathways for fluid flow and, 
potentially, contaminant transport between any intersected zones. For, example, such boreholes could provide 
pathways for vertical flow between transmissive units in the Rustler, or between the Culebra and units below the 
Salado, which could affect fluid densities, flow rates, and flow directions. 
SECONDARY YMP FEP NUMBER: 1.4.04.02.06 
FEP NAME: Borehole-induced mineralization 
ORIGINATOR FEP DESCRIPTION: ... Fluid flow between hydraulically conductive horizons through a 
borehole may result in changes in permeability in the effected units through mineral precipitation. For example: 
Limited calcite precipitation may occur as the brines mix in the Culebra immediately surrounding the borehole, and 
calcite dissolution may occur as the brines migrate away from the borehole due to variations in water chemistry 
along the flow path. 
SECONDARY YMP FEP NUMBER: 1.4.04.02.07 
FEP NAME: Borehole-induced geochemical changes 
ORIGINATOR FEP DESCRIPTION: Movement of fluids through abandoned boreholes could result in 
borehole-induced geochemical changes in the receiving units such as the Salado interbeds or Culebra. Such 
geochemical changes could alter radionuclide migration rates within the disposal system in the affected units if they 
occur sufficiently close to the edge of the controlled area, or if they occur as a result of flow through existing 
boreholes within the controlled area through their effects on colloid transport and sorption.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 II-6 March 2000 
PRIMARY YMP FEP NUMBER: 2.1.05.01.00 
FEP NAME: Seal physical properties 
ORIGINATOR FEP DESCRIPTION: Physical properties are specified for the five materials that will be 
used in the shaft seal system: clay, salt, concrete, asphalt, and earthen fill. The permeability of concrete is 
assumed to increase after 400 years due to degradation. etc. 
YMP PRIMARY FEP DESCRIPTION: Physical properties of the seals emplaced in the access 
ramps, ventilation shafts, and exploratory boreholes may affect the long-term performance of the disposal 
system. These properties include the location of the seals (and the openings they seal), and the physical and 
chemical characteristics of the sealing materials. 
SECONDARY YMP FEP NUMBER: 2.1.05.01.01 
FEP NAME: Seal geometry 
ORIGINATOR FEP DESCRIPTION: The four shafts connecting the WIPP repository to the surface are 
represented in performance assessment with a single shaft with a cross section and volume equal to the total cross 
section and volume of the four real shafts it represents. etc. 
SECONDARY YMP FEP NUMBER: 2.1.05.01.02 
FEP NAME: Consolidation of seals 
ORIGINATOR FEP DESCRIPTION: The conceptual model for the shafts and shaft seals used in 
performance assessment has been chosen to provide a reasonable and realistic basis for simulating long-term fluid 
flow through the shaft seal system and to allow evaluation of the effect that uncertainty about long-term properties 
of the shaft seal system may have on cumulative radionuclide releases from the disposal system. 
SECONDARY YMP FEP NUMBER: 2.1.05.01.03 
FEP NAME Shaft and tunnel seals 
ORIGINATOR FEP DESCRIPTION: At closure, massive concrete tunnel seals and bentonite-concrete rock 
grouting will be emplaced to hydraulically isolate the individual HLW panels and TRU silos from each other and 
from higher permeability zones in the host rock. Similar seals will be emplaced in the shafts and investigation 
boreholes. 
PRIMARY YMP FEP NUMBER: 2.1.05.02.00 
FEP NAME: Groundwater flow and radionuclide transport in seals 
ORIGINATOR FEP DESCRIPTION: Localized percolation driven by temperature gradients could lead 
to early failure of seals and grouts, and the formation of new significant flow pathways, within the vault and 
shafts leading to the vault. 
YMP PRIMARY FEP DESCRIPTION: Groundwater flow in through seals in the access ramps, 
ventilation shafts, and exploratory boreholes could affect long-term performance of the disposal system. 
Radionuclide transport through borehole seals below the repository should be considered. 
SECONDARY YMP FEP NUMBER: None 
FEP NAME: None 
ORIGINATOR FEP DESCRIPTION: None

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 II-7 March 2000 
PRIMARY YMP FEP NUMBER: 2.1.05.03.00 
FEP NAME: Seal degradation 
ORIGINATOR FEP DESCRIPTION: Failure of the shaft seals and grouts could modify flow and 
transport properties, including enhanced transport within the shafts (possibly with percolation) and between 
the seals and rock. 
YMP PRIMARY FEP DESCRIPTION: Degradation of seals in the access ramps, ventilation 
shafts, and exploratory boreholes could modify flow and transport properties, including enhanced flow and 
transport between the surface and the repository . Possible mechanisms for seal degradation include: 
chemical alteration from water interactions, wetting associated with condensation, and thermally -induced 
stress-strain changes. 
SECONDARY YMP FEP NUMBER: 2.1.05.03.01 
FEP NAME: Seal evolution 
ORIGINATOR FEP DESCRIPTION: The properties of the seals and grouts could evolve in time, due to 
processes such as silica cementation, alteration or dissolution of seal and grout materials. 
SECONDARY YMP FEP NUMBER: 2.1.05.03.02 
FEP NAME: Seal failure 
ORIGINATOR FEP DESCRIPTION: Chemical or physical processes may cause early or accelerated failure 
of the seals and grouts. This would lead to changed water flow patterns and transport pathways to and from the 
vault. 
SECONDARY YMP FEP NUMBER: 2.1.05.03.03 
FEP NAME: Degradation of hole and shaft seals 
ORIGINATOR FEP DESCRIPTION: In this context, degradation is a physical or chemical process leading to 
reduced or completely lost sealing capacity. 
SECONDARY YMP FEP NUMBER: 2.1.05.03.04 
FEP NAME: Shaft or access tunnel seal failure and degradation 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 2.1.05.03.05 
FEP NAME: Degradation of hole and shaft seals 
ORIGINATOR FEP DESCRIPTION: Considers the degradation of the material used to seal investigation 
boreholes and access shafts in the repository. In this context degradation is a physical or chemical process leading to 
reduced or completely lost sealing of boreholes and access shafts. etc. 
SECONDARY YMP FEP NUMBER: 2.1.05.03.06 
FEP NAME: Loss of integrity of shaft or access tunnel seals 
ORIGINATOR FEP DESCRIPTION: Access to the repository during the operational phase will be via two 
parallel long (two kilometers) spiral tunnel from the surface which are likely to be lined with concrete. ... The access 
tunnels and ventilation shafts will be backfilled and sealed at closure. If the seals fail, the tunnel and shafts will 
provide short-circuit pathways to the surface. 
SECONDARY YMP FEP NUMBER: 2.1.05.03.07 
FEP NAME: Mechanical degradation of seals

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 II-8 March 2000 
ORIGINATOR FEP DESCRIPTION: ... Shaft seal materials have been selected in part because of their 
exceptional durability. ... Concrete has been shown to degrade under certain conditions, and clays can be more 
transmissive to brine than potable water. etc. 
SECONDARY YMP FEP NUMBER: 2.1.05.03.08 
FEP NAME: Chemical degradation of seals 
ORIGINATOR FEP DESCRIPTION: The conceptual model for the shafts and shaft seals used in the 
performance assessment has been chosen to provide a reasonable and realistic basis for simulating long-term fluid 
flow through the shaft seal system and to allow evaluation of the effect that uncertainty about the long-term 
properties of the shaft seal system may have on cumulative radionuclide releases from the disposal system.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 III-1 March 2000 
ATTACHMENT III 
EXTREME CLIMATE / EPISODIC TRANSIENT FLOW FEPS DESCRIPTIONS

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 III-2 March 2000 
PRIMARY YMP FEP NUMBER: 1.3.04.00.00 
FEP NAME: Periglacial effects 
ORIGINATOR FEP DESCRIPTION: Periglacial effects refers to FEPs related to the physical processes 
and associated landforms in cold but ice-sheet-free environments. 
YMP PRIMARY FEP DESCRIPTION: This category category contains FEPs related to the physical 
processes and associated landforms in cold but ice-sheet-free environments. Permafrost and seasonal 
freeze/thaw cycles are characteristic of periglacial environments. 
SECONDARY YMP FEP NUMBER: 1.3.04.00.01 
FEP NAME: Permafrost 
ORIGINATOR FEP DESCRIPTION: There are lot of evidences that Sweden has gone through several cycles 
of permafrost during the quaternary period (last 2 Myr.). At present, in the Spitzbergen area, the permafrost depth is 
450 m, and in Siberia, depths exceeding 1500 m have been reported. 
SECONDARY YMP FEP NUMBER: 1.3.04.00.02 
FEP NAME: Accumulation of gases under permafrost 
ORIGINATOR FEP DESCRIPTION: Gases from deeper geological layers might accumulate in the repository 
during permafrost, especially during the early phase when the nearby rock is still kept at higher temperatures. 
SECONDARY YMP FEP NUMBER: 1.3.04.00.03 
FEP NAME: Periglacial effects 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 1.3.04.00.04 
FEP NAME: Frost weathering 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 1.3.04.00.05 
FEP NAME: Solifluction 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 1.3.04.00.06 
FEP NAME: Tundra climate 
ORIGINATOR FEP DESCRIPTION: A tundra climate is characterized by low mean annual temperatures 
which result in a short growing season. etc. [The point is that development of such a climate is possible in northern 
Switzerland during the performance period of a repository]. 
SECONDARY YMP FEP NUMBER: 1.3.04.00.07 
FEP NAME: Permafrost 
ORIGINATOR FEP DESCRIPTION: As the climate cools, air temperature will fall substantially below 
freezing much of the year. If these conditions are sustained, then permafrost (permanently frozen ground) may 
develop. etc. 
SECONDARY YMP FEP NUMBER: 1.3.04.00.08 
FEP NAME: Permafrost

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 III-3 March 2000 
ORIGINATOR FEP DESCRIPTION: There is evidence that Sweden has gone through several cycles for 
permafrost during the Quaternary period (last 2 m y.) At present, in the Spitzbergen area, the permafrost depth is 
approximately 450 m, and in Siberia, depths exceeding 1500 m have been reported. etc. 
SECONDARY YMP FEP NUMBER: 1.3.04.00.09 
FEP NAME: Permafrost 
ORIGINATOR FEP DESCRIPTION: Glaciation has been eliminated from performance assessment 
calculations on the basis of low probability of occurrence over the next 10,000 years. Similarly, a number of 
processes associated with the proximity of an ice sheet or valley glacier , such as permafrost and accelerated slope 
erosion (solifluction) have been eliminated from performance assessment calculations on the basis of low 
probability of occurrence over the next 10,000 years. 
PRIMARY YMP FEP NUMBER: 1.3.05.00.00 
FEP NAME: Glacial and ice sheet effects, local 
ORIGINATOR FEP DESCRIPTION: Local glacial and ice sheet effects refers to FEPs related to the 
effects of glaciers and ice sheets within the region of a repository, e.g. changes in the geomorphology, erosion, 
melt water and hydraulic effects. This is distinct from the effect of large ice masses on global and regional 
climate, c.f. FEP 1.3.01.00.00. 
YMP PRIMARY FEP DESCRIPTION: This category contains FEPs related to the effects of glaciers and 
ice sheets occurring within the region of the repository, including direct geomorphologic effects and 
hydrologic effects. These effects include changes in topography (due to glaciation and melt water), changes in 
flow fields, and isostatic depression and rebound. 
SECONDARY YMP FEP NUMBER: 1.3.05.00.01 
FEP NAME: Glaciation 
ORIGINATOR FEP DESCRIPTION: Glaciation will change stress fields, flow regimes and temperatures. It 
could have many complex effects on processes occurring in the vault. 
SECONDARY YMP FEP NUMBER: 1.3.05.00.02 
FEP NAME: Glaciation 
ORIGINATOR FEP DESCRIPTION: Glaciation may cause activation and creation of faults, changes in 
topography, changes in hydraulic heads, changes in groundwater recharge and discharge zones and isostatic 
depression. ETC. 
SECONDARY YMP FEP NUMBER: 1.3.05.00.03 
FEP NAME: Glaciation 
ORIGINATOR FEP DESCRIPTION: During the past earth history there are many evidences for repeated 
glacial periods. Glacial and interglacial periods have followed each other. etc. 
SECONDARY YMP FEP NUMBER: 1.3.05.00.04 
FEP NAME: Glaciation 
ORIGINATOR FEP DESCRIPTION: None 
SECONDARY YMP FEP NUMBER: 1.3.05.00.05 
FEP NAME: Glacial climate

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 III-4 March 2000 
ORIGINATOR FEP DESCRIPTION: A glacial climate marks the height of a glaciation and is characterized 
by the pressure of an ice mass on the landscape e.g. ice sheet, valley glacier. etc. 
SECONDARY YMP FEP NUMBER: 1.3.05.00.06 
FEP NAME: Glacial erosion/sedimentation 
ORIGINATOR FEP DESCRIPTION: Erosion and sedimentation caused by glacial ice results in over 
deepening of valleys, scouring of upland areas, deposition of glacial moraines and modification of stream channel 
networks. etc. 
SECONDARY YMP FEP NUMBER: 1.3.05.00.07 
FEP NAME: Glacial-fluvial erosion/sedimentation 
ORIGINATOR FEP DESCRIPTION: Erosion and deposition by glacial melt waters occurs early in 
interglacial periods. The process potentially results in down cutting of river channels, deposition of alluvium and 
glacial outwash and formation of stream terraces. etc. 
SECONDARY YMP FEP NUMBER: 1.3.05.00.08 
FEP NAME: Ice sheet effects (loading, melt water recharge) 
ORIGINATOR FEP DESCRIPTION: A scenario that has been postulated in other studies is that, as the ice 
sheet advances then recharge will occur from the melt water formed under pressure at the base of the ice sheet. In 
the case of a static or retreating ice sheet, this water may escape as sub-glacial rivers between the ice and ground. 
etc. 
SECONDARY YMP FEP NUMBER: 1.3.05.00.09 
FEP NAME: Glaciation 
ORIGINATOR FEP DESCRIPTION: The world's climate will for the next 100,000 years be featured by 
periods of glaciations, as it has been over similar periods for the past million years. 
SECONDARY YMP FEP NUMBER: 1.3.05.00.10 
FEP NAME: Glaciation 
ORIGINATOR FEP DESCRIPTION: No evidence exists to suggest that the northern part of the Delaware 
Basin has been covered by continental glaciers at any time since the beginning of the Paleozoic Era. etc. 
SECONDARY YMP FEP NUMBER: 1.3.05.00.11 
FEP NAME: Glaciation 
ORIGINATOR FEP DESCRIPTION: Continental glaciation may influence the disposal system and bring 
about massive disruptions in the biosphere. 
SECONDARY YMP FEP NUMBER: 1.3.05.00.12 
FEP NAME: Isostatic rebound 
ORIGINATOR FEP DESCRIPTION: The presence of heavy loads on the earth's surface, such as several 
kilometers of glacial ice, may compress and depress underlying rock, followed by rebound effects when the load is 
removed.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 III-5 March 2000 
PRIMARY YMP FEP NUMBER: 1.3.07.01.00 
FEP NAME: Drought / water table decline 
ORIGINATOR FEP DESCRIPTION: The current levels of meteoric precipitation could change 
substantially, leading to much less flow of water through the geosphere, with accompanying changes to the 
biosphere. 
YMP PRIMARY FEP DESCRIPTION: Extreme climate change could produce an extended drought, 
leading to a decline in the water table in the saturated zone and affecting the release and exposure pathways 
from the repository. 
SECONDARY YMP FEP NUMBER: 1.3.07.01.01 
FEP NAME: Desert and unsaturation 
ORIGINATOR FEP DESCRIPTION: Extreme climate change (perhaps human induced) could result in 
desaturation of the saturated zone, thereby affecting the release and exposure pathways from the repository. 
SECONDARY YMP FEP NUMBER: 1.3.07.01.02 
FEP NAME: Dust storms and desertification 
ORIGINATOR FEP DESCRIPTION: The focus here is on large scale desertification as a result of extended 
drought. Thus, there could be deforestation and much of the grassland could also disappear. The exposed soil would 
erode and dust storms might become a common feature. etc. 
PRIMARY YMP FEP NUMBER: 1.4.01.01.00 
FEP NAME: Climate modification increases recharge 
ORIGINATOR FEP DESCRIPTION: An increase in recharge at the repository site due to artificial 
climate change increases unsaturated flux through the repository. 
YMP PRIMARY FEP DESCRIPTION: Climate modification causes an increase in recharge in the Yucca 
Mountain region. Increased recharge might lead to increased flux through the repository, perched water, or 
water table rise. 
SECONDARY YMP FEP NUMBER: 1.4.01.01.01 
FEP NAME: Climate modification causes perched water to develop at base of Topopah Spring unit 
ORIGINATOR FEP DESCRIPTION: Climate modification causes an increased recharge producing perched 
water which develops at the base of the Topopah Spring nonwelded unit. Flow through the Calico Hills unit is 
fracture flow which drains the perched zone. 
SECONDARY YMP FEP NUMBER: 1.4.01.01.02 
FEP NAME: Climate modification causes perched water to develop above repository 
ORIGINATOR FEP DESCRIPTION: Climate modification causes perched water conditions to develop above 
the repository, diverting downward flow through the repository in localized zones. 
SECONDARY YMP FEP NUMBER: 1.4.01.01.03 
FEP NAME: Climate modification raises water table 
ORIGINATOR FEP DESCRIPTION: Deliberate human action to modify the climate raises the water table 
under Yucca Mtn., shortening the distance from the repository to the water table and therefore the residence of 
contaminants in the UZ.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 III-6 March 2000 
SECONDARY YMP FEP NUMBER: 1.4.01.01.04 
FEP NAME: Climate modification raises water table to flood repository 
ORIGINATOR FEP DESCRIPTION: Increased recharge due to climate modification raises the regional water 
table sufficiently to flood the repository. 
SECONDARY YMP FEP NUMBER: 1.4.01.01.05 
FEP NAME: Climate modification raises water table to short circuit flow barrier in SZ 
ORIGINATOR FEP DESCRIPTION: A higher water table due to climate modification short-circuits a flow 
barrier in the saturated zone, changing the pattern of flow. 
PRIMARY YMP FEP NUMBER: 2.2.07.05.00 
FEP NAME: Flow and transport in the UZ from episodic infiltration 
ORIGINATOR FEP DESCRIPTION: Identified as "Unsaturated flow plume forms from infiltration and 
descends to interact with repository" by originator. An unsaturated flow plume (matrix flow w/o saturating 
pores) forms during an episodic precipitation event and descends to interact with the repository, either with 
the vaporization isotherm and condensate during the thermal period or entering the drifts in the postthermal 
period. 
YMP PRIMARY FEP DESCRIPTION: Episodic flow occurs in the UZ as a result of episodic infiltration. 
See also FEP 2.2.07.02.00 (unsaturated groundwater flow), 2.3.11.03.00 (infiltration), 2.2.07.04.00 (focusing of 
UZ flow), and 1.3.01.00.00 (climate change). Episodic flow may affect transport; for example, colloidal 
transport may be enhanced by episodic flow. 
SECONDARY YMP FEP NUMBER: 2.2.07.05.01 
FEP NAME: Episodic infiltration enhances colloid transport 
ORIGINATOR FEP DESCRIPTION: Pulsed flow into the repository, resulting from episodic infiltration, can 
enhance the release and transport of colloids. 
PRIMARY YMP FEP NUMBER: 2.2.07.06.00 
FEP NAME: Episodic / pulse release from repository 
ORIGINATOR FEP DESCRIPTION: None provided. 
YMP PRIMARY FEP DESCRIPTION: Episodic release of radionuclides from the repository and 
radionuclide transport in the UZ may occur both because of episodic flow into the repository (see 
2.2.07.05.00, episodic flow in UZ), and because of other factors including intermittent failures of waste 
packages. 
SECONDARY YMP FEP NUMBER: None 
FEP NAME: None 
ORIGINATOR FEP DESCRIPTION: None

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 III-7 March 2000 
PRIMARY YMP FEP NUMBER: 2.2.07.07.00 
FEP NAME: Perched water develops 
ORIGINATOR FEP DESCRIPTION: Identified as "Perched water develops above repository" by 
originator. Perched water develops above the repository, diverting downward flow into fracture zones 
draining the perched water table. 
YMP PRIMARY FEP DESCRIPTION: Zones of perched water may develop above the water table. If these 
zones occur above the repository, they may affect UZ flow between the surface and the waste packages. If 
they develop below the repository, for example at the base of the Topopah Spring welded unit, they may 
affect flow pathways and radionuclide transport between the waste packages and the saturated zone. 
SECONDARY YMP FEP NUMBER: 2.2.07.07.01 
FEP NAME: Perched water develops at base of Topopah Spring welded unit 
ORIGINATOR FEP DESCRIPTION: Perched water develops at the base of the Topopah Spring welded unit. 
Flow through the Calico Hills is diverted into fracture zones draining the perched water table. 
PRIMARY YMP FEP NUMBER: 2.3.11.03.00 
FEP NAME: Infiltration and recharge (hydrologic and chemical effects) 
ORIGINATOR FEP DESCRIPTION: None 
YMP PRIMARY FEP DESCRIPTION: Infiltration into the subsurface provides a boundary condition for 
groundwater flow. The amount and location of the infiltration influences the hydraulic gradient and the 
height of the water table. Different sources of recharge water could change the chemistry of groundwaters 
passing through the repository. Mixing of these waters with other groundwaters could result in precipitation, 
dissolution and altered chemical gradients. 
SECONDARY YMP FEP NUMBER: 2.3.11.03.01 
FEP NAME: Freshwater intrusion (in geosphere) 
ORIGINATOR FEP DESCRIPTION: A number of FEPs , including climate change, can result in changes in 
infiltration and recharge. These changes will affect the height of the water table and hence could affect groundwater 
flow in the Rustler through changes in head gradient. etc. 
SECONDARY YMP FEP NUMBER: 2.3.11.03.02 
FEP NAME: Groundwater recharge/discharge 
ORIGINATOR FEP DESCRIPTION: Groundwater recharge and discharge may affect performance. 
SECONDARY YMP FEP NUMBER: 2.3.11.03.03 
FEP NAME: Equilibrated flow system 
ORIGINATOR FEP DESCRIPTION: There is no net infiltration below a shallow depth. All infiltrating liquid 
either evaporates, is transpired, or is diverted in the near-surface away from the repository 
SECONDARY YMP FEP NUMBER: 2.3.11.03.04 
FEP NAME: Draining flow system 
ORIGINATOR FEP DESCRIPTION: There is no net infiltration. The UZ is draining (despite current 
estimates of infiltration). 
SECONDARY YMP FEP NUMBER: 2.3.11.03.05 
FEP NAME: Recharge groundwater

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 III-8 March 2000 
ORIGINATOR FEP DESCRIPTION: Different sources of recharge water could change the chemistry of 
groundwaters passing through the vault. Mixing of these waters with other groundwaters could result in 
precipitation, dissolution and altered chemical gradients. 
SECONDARY YMP FEP NUMBER: 2.3.11.03.06 
FEP NAME: Surface water chemistry 
ORIGINATOR FEP DESCRIPTION: Surface waters will determine the groundwater conditions in the upper 
most part of the rock, but can also enter deeper down in the geosphere by the existence or the formation of highly 
permeable fracture zones caused by tectonic movements or due to other changes in the stress field in the rock. etc. 
SECONDARY YMP FEP NUMBER: 2.3.11.03.07 
FEP NAME: Runoff is intercepted by wash terraces 
ORIGINATOR FEP DESCRIPTION: Runoff passes over the terraces along the sides of washes, which 
represent past elevations of the wash, before reaching the active wash basin. Some runoff infiltrates into the terraces. 
SECONDARY YMP FEP NUMBER: 2.3.11.03.08 
FEP NAME: Runoff to washes infiltrates and maintains a zone of higher flux to the UZ 
ORIGINATOR FEP DESCRIPTION: Runoff to washes infiltrates the wash bottom and a zone of higher 
moisture flux is maintained below the wash. 
SECONDARY YMP FEP NUMBER: 2.3.11.03.09 
FEP NAME: Flow in ephemeral streams tends to be in channels and is a source of recharge 
ORIGINATOR FEP DESCRIPTION: Flow in washes, the result of runoff, tends to be in the wash channels 
where there is some seepage. This seepage is a source of recharge. 
SECONDARY YMP FEP NUMBER: 2.3.11.03.10 
FEP NAME: Percolation (near surface hydrology) 
ORIGINATOR FEP DESCRIPTION: Percolation is the process of solute transport downwards in the soil 
profile. When P exceeds ETP, taking account of water storage capacity, solutes will move down the soil profile 
towards the aquifer. 
SECONDARY YMP FEP NUMBER: 2.3.11.03.11 
FEP NAME: Groundwater recharge 
ORIGINATOR FEP DESCRIPTION: The DOE addresses issues related to groundwater flow and 
radionuclide transport within the context of a conceptual model of how the natural system works on a large scale. 
SECONDARY YMP FEP NUMBER: 2.3.11.03.12 
FEP NAME: Infiltration (near surface hydrology) 
ORIGINATOR FEP DESCRIPTION: The DOE addresses issues related to groundwater flow and 
radionuclide transport within the context of a conceptual model of how the natural system works on a large scale. 
SECONDARY YMP FEP NUMBER: 2.3.11.03.13 
FEP NAME: Recharge groundwater (affects waste and EBS) 
ORIGINATOR FEP DESCRIPTION: Different sources of recharge water or intrusion of saline water could 
affect the chemistry of the groundwaters passing through the vault. 
SECONDARY YMP FEP NUMBER: 2.3.11.03.14 
FEP NAME: Effective moisture (recharge)

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 III-9 March 2000 
ORIGINATOR FEP DESCRIPTION: Effective moisture is the net flux of water available for groundwater 
recharge, taking into account precipitation, evaporation, transpiration and run-off,and incorporating such climatic 
factors as temperature, cloud cover and humidity. 
SECONDARY YMP FEP NUMBER: 2.3.11.03.15 
FEP NAME: Changes in groundwater recharge and discharge 
ORIGINATOR FEP DESCRIPTION: Changes in recharge may affect groundwater flow and radionuclide 
transport in units such as the Culebra and Magenta. 
SECONDARY YMP FEP NUMBER: 2.3.11.03.16 
FEP NAME: Coupling of surface water flow to climate/hydrologic modeling system 
ORIGINATOR FEP DESCRIPTION: Analysis of the effects of surface water flow on the overall hydrologic 
system needs to be shown. The impact of rare, episodic surface water flow events (100-500 year floods) for current 
climate conditions, and overall enhanced surface water flow which will be much more significant for wetter 
climates.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 IV-1 March 2000 
ATTACHMENT IV 
EROSION/DISSOLUTON/SUBSIDENCE FEPS DESCRIPTIONS

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 IV-2 March 2000 
PRIMARY YMP FEP NUMBER: 1.2.07.01.00 
FEP NAME: Erosion/denudation 
ORIGINATOR FEP DESCRIPTION: Erosion and denudation are processes which cause significant 
changes in the present-day topography and thus affect local and regional hydrology and the biosphere. The 
extent of erosion depends to a large extent on climate and uplift. 
YMP PRIMARY FEP DESCRIPTION: Erosion and denudation are processes which cause significant 
changes in the present-day topography and thus affect local and regional hydrology and the biosphere. 
Erosion of surficial materials can occur by a variety of means, including physical weathering (including 
glacial and fluvial erosion), chemical weathering, erosion by wind (aeolian erosion), and mass wasting (e.g., 
landslide) processes. The extent of erosion depends to a large extent on climate and uplift. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.01 
FEP NAME: Major incision 
ORIGINATOR FEP DESCRIPTION: Any mechanism which may cut a deep channel into surface rocks. A 
deep incision may affect the groundwater flow patterns and may reduce the distance from repository to biosphere for 
radionuclide transport. ... The only mechanism likely to cause major incision is thought to be glacial erosion. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.02 
FEP NAME: Generalized denudation 
ORIGINATOR FEP DESCRIPTION: The erosion of the land-surface on a regional scale due to glacial, 
fluvial and aeolian processes. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.03 
FEP NAME: Localized denudation 
ORIGINATOR FEP DESCRIPTION: The erosion of the land-surface on a local scale due to glacial, fluvial 
and coastal processes. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.04 
FEP NAME: Solid discharge via erosional processes 
ORIGINATOR FEP DESCRIPTION: Dissolved radionuclides migrating in the far-field will contaminate the 
far-field rock by sorptive and retardation processes. ... Contaminated far-field rocks will be exhumed by normal 
denudation processes and the rock's radionuclide load will enter the biosphere. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.05 
FEP NAME: Basement alteration 
ORIGINATOR FEP DESCRIPTION: Local removal of the sedimentary cover and the southward shift of the 
Rhine may result in changes to the hydrologic regime in the basement, especially in the higher-permeability domain. 
The nearer-surface crystalline basement has been progressively altered in the past as a result of stress field and rockwater 
interactions, especially hydrothermal alteration, which has been more significant in the higher-permeability 
domain than in the low-permeability domain. etc. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.06 
FEP NAME: Hydraulic gradient changes (magnitude, direction) (in geosphere) 
ORIGINATOR FEP DESCRIPTION: As a result of continuing action of geological processes, the future 
surface geology of Northern Switzerland will be different to the present one. The effect of certain erosion processes, 
such as removal of the Quaternary gravels or denudation (uniform erosion to a maximum of 100m), are not expected 
to be hydraulically relevant for groundwater flow in the crystalline basement.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 IV-3 March 2000 
SECONDARY YMP FEP NUMBER: 1.2.07.01.07 
FEP NAME: Hydraulic gradient changes (magnitude, direction) 
ORIGINATOR FEP DESCRIPTION: As a result of continuing action of geological processes, the future 
surface geology of Northern Switzerland will be different to the present one. The effect of certain erosion processes, 
such as removal of the Quaternary gravels or denudation(uniform erosion to a maximum of 100m), are not expected 
to be hydraulically relevant for groundwater flow in the crystalline basement. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.08 
FEP NAME: Ephemeral stream erosion cuts Tiva Canyon units to underlying nonwelded units 
ORIGINATOR FEP DESCRIPTION: Beds of intermittent streams now resting on the Tiva Canyon welded 
tuff unit erode through to the underlying nonwelded unit. These washes form a barrier to lateral flow in the Tiva 
Canyon and divert flow downward. Regions of high flux are formed below them. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.09 
FEP NAME: Land slide 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.10 
FEP NAME: Stream erosion of Amargosa River lowers base levels and increases gradient in SZ 
ORIGINATOR FEP DESCRIPTION: Entrenchment of the Amargosa River at Alkali Flat lowers base levels 
and increases regional gradients. Regional hydraulic relations are such that water-table lowering at Yucca 
Mountain is insignificant, but increases in groundwater velocity are significant. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.11 
FEP NAME: Erosion 
ORIGINATOR FEP DESCRIPTION: Massive erosion of rock (by glaciation or water) could result in 
significant changes to hydraulic heads and a shorter transport path for contaminants. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.12 
FEP NAME: Erosion - lateral transport 
ORIGINATOR FEP DESCRIPTION: Erosion of soil, overburden and bedrock by wind, water or ice may 
move contaminating radionuclides laterally away from the area occupied by the critical group and reduce local 
contamination. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.13 
FEP NAME: Erosion (wind) 
ORIGINATOR FEP DESCRIPTION: Soil and other materials contaminated with radionuclides may be 
exposed and eroded by wind action, and dispersed in the environment. This would remove radioactivity from the 
area occupied by the critical group, particularly because radionuclides tend to adhere to small clay particles which 
are more easily carried away than bulk soil. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.14 
FEP NAME: Erosion on surface/sediments 
ORIGINATOR FEP DESCRIPTION: Erosion of surface sediments (and crystalline bedrock) is a 
continuously ongoing process due to weathering. etc. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.15 
FEP NAME: Denudation

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 IV-4 March 2000 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.16 
FEP NAME: River, stream channel erosion 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.17 
FEP NAME: Chemical denudation and weathering 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.18 
FEP NAME: Erosion 
ORIGINATOR FEP DESCRIPTION: As a result of continuing action of geological processes, the future 
surface geology of Northern Switzerland will be different to the present one. The effect of certain erosion processes, 
such as the removal of Quaternary gravels or denudation(uniform erosion--max. 100 m), are not expected to be 
hydraulically relevant for groundwater flow in the HPD. etc. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.19 
FEP NAME: Erosion/deposition 
ORIGINATOR FEP DESCRIPTION: Erosion/deposition (fluvial, glacial or glacial-fluvial) in the biosphere 
(alluvium of the Rhine river valley) is affected by both geologic and climatic FEPs (see geologic and climatic 
domains, sections 9 and 10). ... These processes may significantly affect the transport mechanism for radionuclides 
in the biosphere, over long timescales. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.20 
FEP NAME: Fluvial erosion/sedimentation 
ORIGINATOR FEP DESCRIPTION: Fluvial erosion/sedimentation is affected by climatic factors as well as 
geological factors-the impact on domains depends on the net amount of fluvial erosion/sediment caused by these 
two controlling factors. etc. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.21 
FEP NAME: Surface denudation 
ORIGINATOR FEP DESCRIPTION: Surface denudation is caused by surface loosening and intensive in-situ 
weathering brought about by a range of factors including, large temperature fluctuations, permafrost, changes in 
vegetation, etc. ... The corresponding erosion potential in Northern Switzerland is estimated to be 50m per million 
years for an arid climate, and 100m per million years for a humid/glacial climate. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.22 
FEP NAME: Chemical weathering 
ORIGINATOR FEP DESCRIPTION: Chemical weathering is assumed to be occurring at or near the surface 
around the WIPP site, through processes such as exfoliation and leaching. The extent of this process is limited and 
will contribute little to the overall rate of erosion in the area or to the availability of material for other erosional 
processes. etc. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.23 
FEP NAME: Aeolian erosion

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 IV-5 March 2000 
ORIGINATOR FEP DESCRIPTION: The geomorphological regime on the Mescalero Plain (Los Medanos) 
in the region of the WIPP is dominated by aeolian processes. Dunes are present in the area, and although some are 
stabilized by vegetation, aeolian erosion will occur as they migrate across the area. etc. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.24 
FEP NAME: Fluvial erosion 
ORIGINATOR FEP DESCRIPTION: Currently, precipitation in the region of WIPP is too low (about 13 
inches per year) to cause perennial streams, and the relief in the area is too low for extensive sheet flood erosion 
during storms. etc. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.25 
FEP NAME: Mass wasting 
ORIGINATOR FEP DESCRIPTION: Mass wasting (the down slope movement of material caused by the 
direct effect of gravity) is important only in terms of sediment erosion in regions of steep slopes. In the vicinity of 
WIPP, mass wasting will be insignificant under the climatic conditions expected over the next 10,000 years. etc. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.26 
FEP NAME: Mass wasting 
ORIGINATOR FEP DESCRIPTION: Mass wasting may be significant for sedimentary deposition if it results 
in dams or modifies streams. In the region around WIPP, the Pecos River forms a significant water course some 12 
miles away, but the broadness of the valley precludes either significant mass wasting or the formation of large 
impoundments. 
SECONDARY YMP FEP NUMBER: 1.2.07.01.27 
FEP NAME: Mechanical weathering 
ORIGINATOR FEP DESCRIPTION: Mechanical weathering is assumed to be occurring at or near the 
surface around the WIPP site, through processes such as exfoliation and leaching. The extent of this processes is 
limited and will contribute little to the overall rate of erosion in the area or to the availability of material for other 
erosional processes. The effects of mechanical weathering have been eliminated from performance assessment 
calculations on the basis of low consequence to the performance of the disposal system. 
.
PRIMARY YMP FEP NUMBER: 1.2.07.02.00 
FEP NAME: Deposition 
ORIGINATOR FEP DESCRIPTION: (Identified as "Fluvial deposition" by originator) 
The limited extent of water courses in the region of the WIPP, under both present-day conditions and under 
the expected climatic conditions, will restrict the amount of fluvial deposition in the region. 
YMP PRIMARY FEP DESCRIPTION: Deposition and erosion are processes which cause significant 
changes in the present-day topography and thus affect local and regional hydrology and the biosphere. 
Deposition of surficial materials can occur by a variety of means, including fluvial, aeolian, and lacustrine 
deposition and redistribution of soil through weathering and mass wasting processes. 
SECONDARY YMP FEP NUMBER: 1.2.07.02.01 
FEP NAME: Aeolian deposition 
ORIGINATOR FEP DESCRIPTION: The geomorphological regime on the Mescalero Plain (Los Medanos) 
in the region of the WIPP is dominated by aeolian processes but, although some dunes are stabilized by vegetation, 
no significant changes in overall thickness of aeolian material are expected to occur. etc. 
SECONDARY YMP FEP NUMBER: 1.2.07.02.02 
FEP NAME: Lacustrine deposition

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 IV-6 March 2000 
ORIGINATOR FEP DESCRIPTION: The limited extent of water courses in the region of WIPP, under both 
present-day conditions and under the expected climatic conditions, will restrict the amount of lacustrine deposition 
in the region. 
PRIMARY YMP FEP NUMBER: 1.2.09.02.00 
FEP NAME: Large-scale dissolution 
ORIGINATOR FEP DESCRIPTION: (Identified as "Deep dissolution" by originator) 
Deep dissolution takes place in the Castile and the base of the Salado. Deep dissolution refers to the 
dissolution of salt or other evaporite minerals in a formation at depth. etc. (WIPP) 
YMP PRIMARY FEP DESCRIPTION: Dissolution can occur when any soluble mineral is removed by 
flowing water, and large-scale dissolution is a potentially important process in rocks that are composed 
predominantly of water-soluble evaporite minerals, such as salt. 
SECONDARY YMP FEP NUMBER: 1.2.09.02.01 
FEP NAME: Shallow dissolution 
ORIGINATOR FEP DESCRIPTION: Shallow dissolution involves percolation of groundwater and mineral 
dissolution in the Rustler. ... Extensive dissolution may create cavities (karst) and result in the total collapse of 
overlying units. 
SECONDARY YMP FEP NUMBER: 1.2.09.02.02 
FEP NAME: Lateral dissolution 
ORIGINATOR FEP DESCRIPTION: Lateral dissolution involves dissolution at the top of the Salado. ... 
Lateral dissolution takes place when percolating groundwater dissolves halite at the top of the Salado, causing 
collapse of the overlying Rustler with consequent changes in hydrogeological properties. etc. 
SECONDARY YMP FEP NUMBER: 1.2.09.02.03 
FEP NAME: Solution chimneys 
ORIGINATOR FEP DESCRIPTION: Deep dissolution takes place in the Castile and the base of the Salado. 
... Dissolution by groundwater from deep water-bearing zones can lead to formation of cavities. If dissolution is 
extensive, breccia pipes or solution chimneys may form above the cavity. etc. 
SECONDARY YMP FEP NUMBER: 1.2.09.02.04 
FEP NAME: Breccia pipes 
ORIGINATOR FEP DESCRIPTION: Deep dissolution takes place in the Castile and the base of the Salado. 
... Dissolution by groundwater from deep water-bearing zones can lead to formation of cavities. If dissolution is 
extensive, breccia pipes or solution chimneys may form above the cavity. ... These pipes may reach the surface or 
pass upwards into fractures and then into micro cracks that do not extend to the surface. etc. 
SECONDARY YMP FEP NUMBER: 1.2.09.02.05 
FEP NAME: Collapse breccias 
ORIGINATOR FEP DESCRIPTION: ... Collapse breccias are present at several places around the margin of 
the Delaware Basin. Their formation is attributed to relatively fresh groundwater from the Capitan Limestone that 
forms the margin of the basin. etc.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 IV-7 March 2000 
PRIMARY YMP FEP NUMBER: 2.2.06.04.00 
FEP NAME: Effects of subsidence 
ORIGINATOR FEP DESCRIPTION: Identified as "Subsidence of mined facility alters drainage" by 
originator. Subsidence of the mined underground facility creates impoundments or diverts drainage, thereby 
increasing the local percolation flux to values not currently seen. 
YMP PRIMARY FEP DESCRIPTION: Subsidence above the mined underground facility or other 
openings affects the properties of the overlying rocks and surface topography. Changes in rock properties, 
such as enhanced permeability, may alter flow paths from the surface to the repository. Changes in surface 
topography may alter run-off and infiltration, and may perhaps create impoundments. 
SECONDARY YMP FEP NUMBER: 2.2.06.04.01 
FEP NAME: Subsidence 
ORIGINATOR FEP DESCRIPTION: Subsidence through salt creep or roof collapse associated with 
excavation might affect the hydrologic properties of units above the repository. 
SECONDARY YMP FEP NUMBER: 2.2.06.04.02 
FEP NAME: Large-scale rock fracturing 
ORIGINATOR FEP DESCRIPTION: Subsidence through salt creep or roof collapse associated with 
excavation might cause large-scale rock fracturing between the repository horizon and the surface. 
SECONDARY YMP FEP NUMBER: 2.2.06.04.03 
FEP NAME: Borehole-induced solution and subsidence 
ORIGINATOR FEP DESCRIPTION: Potentially, boreholes could provide pathways for surface-derived 
water or groundwater to percolate through low-permeability strata and into formations containing soluble minerals. 
Large-scale dissolution through this mechanism could lead to subsidence and to changes in groundwater flow 
patterns.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 V-1 March 2000 
ATTACHMENT V 
HUMAN INFLUENCES ON CLIMATE/SOIL FEPS DESCRIPTIONS

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 V-2 March 2000 
PRIMARY YMP FEP NUMBER: 1.4.01.00.00 
FEP NAME: Human influences on climate 
ORIGINATOR FEP DESCRIPTION: Human influences on climate refers to FEPs related to human 
activities that could affect the change of climate either globally or in a region. 
YMP PRIMARY FEP DESCRIPTION: This category contains FEPs related to future human actions that 
could influence global, regional, or local climate. Human actions may be intentional or accidental. This FEP 
aggregates all human influences on climate into a single category. Technical discussions are presented 
separately for increased recharge (1.4.01.01.00), greenhouse gas effects (1.4.01.02.00), acid rain (1.4.01.03.00), 
and ozone layer failure (1.4.01.04.00). 
SECONDARY YMP FEP NUMBER: 1.4.01.00.01 
FEP NAME: Human-induced climate change 
ORIGINATOR FEP DESCRIPTION: Climate alteration, intentional or accidental, produced by human 
actions. 
SECONDARY YMP FEP NUMBER: 1.4.01.00.02 
FEP NAME: Anthropogenic climate change 
ORIGINATOR FEP DESCRIPTION: None 
SECONDARY YMP FEP NUMBER: 1.4.01.00.03 
FEP NAME: Human-induced climate change 
ORIGINATOR FEP DESCRIPTION: The impact of anthropogenic greenhouse gases (e.g. CO2, CH4,etc.) on 
the climate is unclear. However the general consensus is that anthropogenically induced climate forcing will/may 
marginally delay but not prevent a next ice age. etc. 
SECONDARY YMP FEP NUMBER: 1.4.01.00.04 
FEP NAME: Climate change: Human induced 
ORIGINATOR FEP DESCRIPTION: Changes to climate due to human activities, e.g. release of greenhouse 
gases to the atmosphere. etc. 
PRIMARY YMP FEP NUMBER: 1.4.01.02.00 
FEP NAME: Greenhouse gas effects 
ORIGINATOR FEP DESCRIPTION: (Identified as "greenhouse effect" by originator) 
The greenhouse effect could increase concentrations of carbon dioxide and other gases in the atmosphere, and 
lead to changes in climate at the disposal site. 
YMP PRIMARY FEP DESCRIPTION: The greenhouse effect refers to the presence of carbon dioxide and 
other gases in the atmosphere that tend to allow solar radiation through to the earth's surface and reflect heat 
back to it. Thus, these gases act much as the glass of a greenhouse, with the earth as the greenhouse. Human 
activities such as burning of fossil fuels, forest clearance, and industrial processes produce these greenhouse 
gases. The greenhouse effect could increase concentrations of carbon dioxide and other gases in the 
atmosphere, and lead to changes in climate such as global warming.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 V-3 March 2000 
SECONDARY YMP FEP NUMBER: 1.4.01.02.01 
FEP NAME: Greenhouse effect 
ORIGINATOR FEP DESCRIPTION: The greenhouse effect refers to the presence of carbon dioxide and 
other gases in the atmosphere that tend to allow solar radiation through to the earth's surface and reflect heat back to 
it. Thus, these gases act much as the glass of a greenhouse, with the earth as the greenhouse. A key concern of a 
significant human-produced increase in these gases in the atmosphere over the last 150 years is massive climatic 
change. For the Shield, this might mean a warmer and drier climate for, perhaps, hundreds of years. The duration of 
the stronger greenhouse effect would depend on further contributions to the greenhouse gases, such as from burning 
fossil fuels, and the rate of disappearance of the gases into peat, the seas and sedimentary deposits. 
SECONDARY YMP FEP NUMBER: 1.4.01.02.02 
FEP NAME: Greenhouse gas effects 
ORIGINATOR FEP DESCRIPTION: ... The effects of anthropogenic climate change may be on a local to 
regional scale(acid rain) or on a regional to global scale (greenhouse gas effects and damage to the ozone layer). Of 
these anthropogenic effects, only the greenhouse gas effect could influence groundwater recharge in the WIPP 
region. However, consistent with the future states assumptions in 40 CFR 194.25(a), compliance assessments and 
performance assessments need not consider indirect anthropogenic effects on disposal performance. 
SECONDARY YMP FEP NUMBER: 1.4.01.02.03 
FEP NAME: Greenhouse gas effects 
ORIGINATOR FEP DESCRIPTION: Global changes in climate and sea levels caused by a warming of the 
atmosphere may occur due to the release of gases, principally carbon dioxide but also chlorofluorocarbons (CFCs) 
and water vapor, through human activities (e.g., burning of fossil fuels, forest clearance, industrial processes). If this 
effect becomes significant markedly warmer climate states are predicted for northern Switzerland. 
PRIMARY YMP FEP NUMBER: 1.4.01.03.00 
FEP NAME: Acid rain 
ORIGINATOR FEP DESCRIPTION: ... The effects of anthropogenic climate change may be on a local to 
regional scale (acid rain) or on a regional to global scale (greenhouse gas effects and damage to the ozone 
layer). Of these anthropogenic effects, only the greenhouse gas effect could influence groundwater recharge in 
the WIPP region. However, consistent with the future states assumptions in 40 CFR 194.25(a), compliance 
assessments and performance assessments need not consider indirect anthropogenic effects on disposal 
performance. 
YMP PRIMARY FEP DESCRIPTION: Human actions may result in acid rain on a local to regional scale. 
Acid rain can detrimentally affect aquatic and terrestrial life by interfering with the growth, reproduction 
and survival of organisms. It can influence the behavior and transport of contaminants in the biosphere, 
particularly by affecting surface water and soil chemistry. 
SECONDARY YMP FEP NUMBER: 1.4.01.03.01 
FEP NAME: Acid rain 
ORIGINATOR FEP DESCRIPTION: Acid rain can detrimentally affect aquatic and terrestrial life by 
interfering with the growth, reproduction and survival of organisms. It can influence the behavior and transport of 
contaminants in the biosphere, particularly in surface water and soil.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 V-4 March 2000 
SECONDARY YMP FEP NUMBER: 1.4.01.03.02 
FEP NAME: Surface water pH 
ORIGINATOR FEP DESCRIPTION: In conjunction with acid rain, the pH of water bodies on the Shield has 
become of major concern. ... The pH can also influence sedimentation of contaminants through the availability of 
suspended particles and the reaction of contaminants with these particles. etc. 
PRIMARY YMP FEP NUMBER: 1.4.01.04.00 
FEP NAME: Ozone layer failure 
ORIGINATOR FEP DESCRIPTION: Certain industrial chemicals may lead to the destruction of the 
earth's ozone layer. Without an ozone layer, UV could penetrate readily down to the earth's surface, which 
would constitute an increase in solar radiation. 
YMP PRIMARY FEP DESCRIPTION: Human actions (i.e., the use of certain industrial chemicals) may 
lead to destruction or damage to the earth's ozone layer. This may lead to significant changes to the climate, 
affecting properties of the geosphere such as groundwater flow patterns. 
SECONDARY YMP FEP NUMBER: 1.4.01.04.01 
FEP NAME: Damage to the ozone layer 
ORIGINATOR FEP DESCRIPTION: ... The effects of anthropogenic climate change may be on a local to 
regional scale (acid rain) or on a regional to global scale (greenhouse gas effects and damage to the ozone layer). Of 
these anthropogenic effects, only the greenhouse gas effect could influence groundwater recharge in the WIPP 
region. However, consistent with the future states assumptions in 40 CFR 194.25(a), compliance assessments and 
performance assessments need not consider indirect anthropogenic effects on disposal performance. 
SECONDARY YMP FEP NUMBER: 1.4.01.04.02 
FEP NAME: Ozone layer 
ORIGINATOR FEP DESCRIPTION: Destruction or damage to the earth's ozone layer may lead to significant 
changes to the climate, affecting properties of the geosphere such as groundwater flow patterns. 
PRIMARY YMP FEP NUMBER: 1.4.06.01.00 
FEP NAME: Altered soil or surface water chemistry 
ORIGINATOR FEP DESCRIPTION: (Identified as "Altered surface water chemistry" by originator) 
The industrial pollution could give rise to considerable change in surface water chemistry by acidic rain, 
increased atmospheric carbon dioxide content, complexing agents in the surface waters,etc. 
YMP PRIMARY FEP DESCRIPTION: Human activities (e.g., industrial pollution, agricultural chemicals) 
may produce local changes to the soil chemistry or to the chemistry of water infiltrating Yucca Mtn and could 
provide a plume of unspecified nature to interact with the repository and possibly with containers. 
SECONDARY YMP FEP NUMBER: 1.4.06.01.01 
FEP NAME: Altered soil or surface water chemistry 
ORIGINATOR FEP DESCRIPTION: None.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 V-5 March 2000 
SECONDARY YMP FEP NUMBER: 1.4.06.01.02 
FEP NAME: Groundwater pollution 
ORIGINATOR FEP DESCRIPTION: Human activity unrelated to the repository may result in pollution of 
the groundwaters, surface waters, soils and sediments. In the case of groundwater pollution, contaminants could 
change the geochemistry of the higher-permeability domain basement rock, and hence affect the speciation, 
solubility and sorption of radionuclides released from the repository. etc. 
SECONDARY YMP FEP NUMBER: 1.4.06.01.03 
FEP NAME: Surface pollution (soils, rivers) 
ORIGINATOR FEP DESCRIPTION: Human activity unrelated to the repository may result in pollution of 
the groundwaters, surface waters, soils and sediments. In the case of groundwater pollution, contaminants could 
change the geochemistry of the higher-permeability domain basement rock, and hence affect the speciation, 
solubility and sorption of radionuclides released from the repository. etc. 
SECONDARY YMP FEP NUMBER: 1.4.06.01.04 
FEP NAME: Altered soil or surface water chemistry by human activities 
ORIGINATOR FEP DESCRIPTION: Potash mining effluent and runoff from oil fields have altered soil and 
surface water chemistry in the vicinity of the WIPP. However, the performance of the disposal will not be sensitive 
to soil and surface water chemistry. Therefore, altered soil and surface water chemistry by human activities have 
been eliminated from performance assessment calculations on the basis of low consequence to the performance of 
the disposal system. 
SECONDARY YMP FEP NUMBER: 1.4.06.01.05 
FEP NAME: Far field hydrochemistry - acids, oxidants, nitrate 
ORIGINATOR FEP DESCRIPTION: The geochemistry might be changed by inflow of chemicals from the 
surface. 
SECONDARY YMP FEP NUMBER: 1.4.06.01.06 
FEP NAME: Arable farming 
ORIGINATOR FEP DESCRIPTION: ... Agricultural activities could affect infiltration and recharge 
conditions in the vicinity of the WIPP. Also, application of acids, oxidants, and nitrates during agricultural practice 
could alter groundwater geochemistry. The EPA has provided criteria relating to future human activities in 40 CFR 
194.32(a), that limit the scope of consideration of future human activities in performance assessments to mining and 
drilling. etc.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VI-1 March 2000 
ATTACHMENT VI 
NATURAL GAS/GAS GENERATION EFFECTS FEPS DESCRIPTIONS

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VI-2 March 2000 
PRIMARY YMP FEP NUMBER: 2.1.12.01.00 
FEP NAME: Gas generation 
ORIGINATOR FEP DESCRIPTION: (Identified as "Gas generation due to corrosion (chemical and/or 
microbial), radiolysis and radioactive decay" by originator) 
Gas is generated by various mechanisms. 
YMP PRIMARY FEP DESCRIPTION: Gas may be generated in the repository by a variety of 
mechanisms. Gas generation might lead to pressurization of the repository, produce multiphase flow, and 
affect radionuclide transport. This FEP aggregates all types of gas generation into a single category. 
Technical discussions are presented separately for gas generation from fuel decay (FEP 2.1.12.02.00), 
corrosion (FEP 2.1.12.03.00), microbial degradation (FEP 2.1.12.04.00), and radiolysis (FEP 2.1.13.01.00). 
SECONDARY YMP FEP NUMBER: 2.1.12.01.01 
FEP NAME: Formation of gases (in wastes and EBS) 
ORIGINATOR FEP DESCRIPTION: Chemical reactions such as radiolysis and corrosion of iron may lead to 
the formation of gases such as hydrogen, oxygen and hydrogen sulfide. Gas pressure could act as a driving force to 
expel contaminated water from the vault or to prevent the ingress of water. 
SECONDARY YMP FEP NUMBER: 2.1.12.01.02 
FEP NAME: Gas generation 
ORIGINATOR FEP DESCRIPTION: Gas generation could be caused by radiolysis, helium production, 
carbon dioxide, organic decomposition, corrosion or changing water chemistry. 
SECONDARY YMP FEP NUMBER: 2.1.12.01.03 
FEP NAME: Gas generation, buffer/backfill 
ORIGINATOR FEP DESCRIPTION: Radiolytic decomposition of water in the vicinity of the canister may 
lead to hydrogen formation in the buffer, and microbial degradation of organics may lead to generation of hydrogen, 
carbon dioxide and methane in the bentonite buffer and in the backfill. etc. 
SECONDARY YMP FEP NUMBER: 2.1.12.01.04 
FEP NAME: Chemotoxic gases (in waste and EBS) 
ORIGINATOR FEP DESCRIPTION: Production of chemotoxic gases that may influence other processes in 
the repository near-field, far-field or biosphere with radiological consequences. The health effects of chemotoxicity 
are not, themselves, of concern in this assessment. 
SECONDARY YMP FEP NUMBER: 2.1.12.01.05 
FEP NAME: Pressurization (in waste and EBS) 
ORIGINATOR FEP DESCRIPTION: Increased gas pressure may slow the rate of salt creep. Closure and 
consolidation can be slowed by fluid pressure in the repository. 
PRIMARY YMP FEP NUMBER: 2.2.10.11.00 
FEP NAME: Natural air flow in unsaturated zone 
ORIGINATOR FEP DESCRIPTION: Natural convective air circulation has been observed at a borehole 
at the top of the mountain. Repository heat is expected to increase this flow. 
YMP PRIMARY FEP DESCRIPTION: Natural convective air circulation has been observed at a borehole 
at the top of the mountain. Repository heat is expected to increase this flow.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VI-3 March 2000 
PRIMARY YMP FEP NUMBER: 2.2.11.01.00 
FEP NAME: Naturally-occurring gases in geosphere 
ORIGINATOR FEP DESCRIPTION: (Identified as "Effects of natural gases" by originator) 
Natural gases may be generated in the vicinity of the repository, or may migrate towards the repository from 
a source elsewhere. In extreme conditions, these gases may influence groundwater flow paths and releases to 
the biosphere. 
YMP PRIMARY FEP DESCRIPTION: Naturally-occurring gases in the geosphere may intrude into the 
repository or may influence groundwater flow paths and releases to the biosphere. Potential sources for gas 
might be clathrates, microbial degradation of organic material or deep gases in general. 
SECONDARY YMP FEP NUMBER: 2.2.11.01.01 
FEP NAME: Methane intrusion (in geosphere) 
ORIGINATOR FEP DESCRIPTION: The potential sources might be clathrates in combination with 
permafrost or deep earth gases in general. 
SECONDARY YMP FEP NUMBER: 2.2.11.01.02 
FEP NAME: Natural gas intrusion 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 2.2.11.01.03 
FEP NAME: Geogas 
ORIGINATOR FEP DESCRIPTION: Geogas may be present in the repository environment. Preliminary 
studies of the Swedish system indicate the existence of a geogas flow( probably nitrogen) and that matter is likely to 
be transported by geogas to the surface. Such transport is likely to be selective, favoring the upward transport of 
colloids and other small particles. etc. 
SECONDARY YMP FEP NUMBER: 2.2.11.01.04 
FEP NAME: Geogas 
ORIGINATOR FEP DESCRIPTION: Geogas may be present in the repository environment. Preliminary 
studies of the Swedish system indicate the existence of a geogas flow( probably nitrogen) and that matter is likely to 
be transported by geogas to the surface. Such transport is likely to be selective, favoring the upward transport of 
colloids and other small particles. etc. 
SECONDARY YMP FEP NUMBER: 2.2.11.01.05 
FEP NAME: Gas generation and gas sources, far-field 
ORIGINATOR FEP DESCRIPTION: Concerns the gas generation and the sources for gas in the geosphere. 
One of the sources is gas generated in the near-field of the repository and transported to the far-field. Other potential 
sources for gas might be clathrates, microbial degradation of organic material or deep gases in general. 
SECONDARY YMP FEP NUMBER: 2.2.11.01.06 
FEP NAME: Natural gas intrusion 
ORIGINATOR FEP DESCRIPTION: Hydrocarbon resources are present in formations beneath the WIPP, 
and natural gas is extracted from the Morrow Formation. These reserves are, however, some 14,000 feet (4,200 
meters) below the surface, and no natural events or processes have been identified that could result in natural gas 
intrusion into the Salado or the units above. 
SECONDARY YMP FEP NUMBER: 2.2.11.01.07 
FEP NAME: Methane

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VI-4 March 2000 
ORIGINATOR FEP DESCRIPTION: Methane in deep groundwaters may be a resource and the object of 
mining activities, or methane may modify the mobility of contaminants (methylation). 
PRIMARY YMP FEP NUMBER: 2.2.11.02.00 
FEP NAME: Gas Pressure effects 
ORIGINATOR FEP DESCRIPTION: Since hydrostatic pressure is much greater than any likely pressure 
variations due to gas generation, significant changes in flow systems are unlikely to result. 
YMP PRIMARY FEP DESCRIPTION: Pressure variations due to gas generation may affect flow patterns 
and contaminant transport in the geosphere. 
SECONDARY YMP FEP NUMBER: 2.2.11.02.01 
FEP NAME: Gas pressure effects 
ORIGINATOR FEP DESCRIPTION: Since hydrostatic pressure is much greater than any likely pressure 
variations due to gas generation, significant changes in flow systems are unlikely to result. 
SECONDARY YMP FEP NUMBER: 2.2.11.02.02 
FEP NAME: Fluid flow due to gas pressurization (in waste and EBS) 
ORIGINATOR FEP DESCRIPTION: Brine contained in the Salado may flow to the waste disposal region 
because of pressure gradients created by the excavation. Brine flow into the repository may be reduced as repository 
pressure increases, and brine may be expelled from the repository if pressure in the repository exceeds brine 
pressure in the immediately surrounding rock or borehole. Gas may be generated as waste decomposes, causing a 
pressure increase. Gas may flow away from the waste into lower pressure areas, which may include disturbed areas 
surrounding the repository, the interbeds, the shafts, or an intrusion borehole. Gas may not be able to flow through 
intact, halite-rich strata of the Salado under realistic conditions for the repository. Gas flow in liquid-saturated rock 
depends on the gas pressure required to overcome capillary resistance to initial gas penetration and development of 
interconnected gas pathways that allow gas flow (threshold pressure). While the permeability of halite is known to 
be low, its threshold pressure has never been measured. An empirical relationship between threshold pressure and 
permeability in non-WIPP rocks (Davies 1991, 17-19) suggests that threshold pressure will be sufficiently high that 
gas will not be able to flow through the halite-rich strata of the Salado under any conditions foreseeable for the 
WIPP. Values used by the DOE for halite threshold pressure are consistent for generic material of low permeability 
and prevent the flow of gas into the impure halite regions. etc. 
SECONDARY YMP FEP NUMBER: 2.2.11.02.03 
FEP NAME: Disruption due to gas effects 
ORIGINATOR FEP DESCRIPTION: [The exact point of this FEP is well disguised in detailed text, but 
appears to be: brine flows between the repository and Salado via these interbeds, with separation of gas phases from 
brine which produces fracturing.]

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VI-5 March 2000 
PRIMARY YMP FEP NUMBER: 2.2.11.03.00 
FEP NAME: Gas transport in geosphere 
ORIGINATOR FEP DESCRIPTION: (Identified as "Gas flow and transport, near-field rock/far field" by 
originator) Gas released from the buffer and backfill and gas generated in the near-field rock will flow 
through fracture systems in the near-field rock and in the geosphere. Gas may dissolve in the groundwater 
and be transported by moving water, but as the pressure decreases in the rising groundwater flow gas may 
again form. If the gas carries radionuclides in gaseous state, this is a fast transport mechanism through the 
geosphere barrier for these nuclides. 
YMP PRIMARY FEP DESCRIPTION: Gas released from the drifts and gas generated in the near-field 
rock will flow through fracture systems in the near-field rock and in the geosphere. Certain gaseous or 
volatile radionuclides may be able to migrate through the far-field faster than the groundwater advection 
rate. Degassing could affect flow and transport of gaseous contaminants. Gases could also affect other 
contaminants if water flow is driven by large gas bubbles forming in the repository. 
SECONDARY YMP FEP NUMBER: 2.2.11.03.01 
FEP NAME: Gases and gas transport (in geosphere) 
ORIGINATOR FEP DESCRIPTION: Contaminants that are volatile or that form gases, or other gases such as 
hydrogen from corrosion of steel, may be transported as gases or in two phase flow. Degassing could therefore 
affect flow and transport of these contaminants. It could also affect other contaminants if water flow is driven by 
large gas bubbles forming in the vault. 
SECONDARY YMP FEP NUMBER: 2.2.11.03.02 
FEP NAME: Far-field transport: Gas induced groundwater transport 
ORIGINATOR FEP DESCRIPTION: Two phase flow (gas and groundwater) occurring in the far-field may 
affect the rate and direction of the groundwater flow by a number of processes. 
SECONDARY YMP FEP NUMBER: 2.2.11.03.03 
FEP NAME: Gas Mediated Transport 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 2.2.11.03.04 
FEP NAME: Far-field transport: Transport of radioactive gases 
ORIGINATOR FEP DESCRIPTION: Certain gaseous or volatile radionuclides may be able to migrate 
through the far-field faster than the groundwater advection rate. 
SECONDARY YMP FEP NUMBER: 2.2.11.03.05 
FEP NAME: Gas discharge 
ORIGINATOR FEP DESCRIPTION: Some radionuclides migrating through the far-field may do so in the 
gas phase, e.g. tritium or 14-C in carbon dioxide or methane. Transfer of gaseous radionuclides from the far-field to 
the biosphere is likely to occur at specific 'entry' points to the biosphere controlled by faults or fractures. 
SECONDARY YMP FEP NUMBER: 2.2.11.03.06 
FEP NAME: Transport of radioactive gases 
ORIGINATOR FEP DESCRIPTION: The production and potential transport of radioactive gases is discussed 
under FEP W2.055, where they are eliminated from performance assessment calculations on the basis of low 
consequence to the performance of the disposal

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VII-1 March 2000 
ATTACHMENT VII 
SEISMIC/IGNEOUS/ROCK CHARACTERISTICS FEPS DESCRIPTIONS

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VII-2 March 2000 
PRIMARY YMP FEP NUMBER: 1.2.02.01.00 
FEP NAME: Fractures 
ORIGINATOR FEP DESCRIPTION: (Identified as "Formation of fractures' by originator) 
Groundwater flow in the region of the WIPP and transport of any released radionuclides may take place 
along fractures. The rate of flow and the extent of transport will be influenced by fracture characteristics 
such as orientation, aperture, asperity, fracture length and connectivity, and the nature of any linings or 
infills. These characteristics are accounted for in the performance assessment calculations through the 
description of the hydrogeological properties of the transmissive units. 
YMP PRIMARY FEP DESCRIPTION: Groundwater flow in the Yucca Mountain region and transport of 
any released radionuclides may take place along fractures. Transmissive fractures may be existing, 
reactivated, or newly formed fractures. The rate of flow and the extent of transport in fractures is influenced 
by characteristics such as orientation, aperture, asperity, fracture length, connectivity, and the nature of any 
linings or infills. Generation of new fractures and reactivation of preexisting fractures may significantly 
change the flow and transport paths. Newly formed and reactivated fractures typically result from thermal, 
seismic, or tectonic events. 
SECONDARY YMP FEP NUMBER: 1.2.02.01.01 
FEP NAME: Changes in fracture properties 
ORIGINATOR FEP DESCRIPTION: Groundwater flow in the region of the WIPP and transport of any 
released radionuclides may take place along fractures. The rate of flow and the extent of transport will be influenced 
by fracture characteristics such as orientation, aperture, asperity, fracture length and connectivity, and the nature of 
any linings or infills. etc. 
SECONDARY YMP FEP NUMBER: 1.2.02.01.02 
FEP NAME: Fracturing 
ORIGINATOR FEP DESCRIPTION: None. 
ORIGINATOR FEP DESCRIPTION: Exit from individual glacial periods will cause large volumes of surface 
water to accumulate as some glaciers melt. Melt water, and its rate of production, have an important effect on 
surface environments, groundwater fluxes and flow directions. 
PRIMARY YMP FEP NUMBER: 1.2.02.02.00 
FEP NAME: Faulting 
ORIGINATOR FEP DESCRIPTION: Faulting may occur due to sudden major changes in the stress 
situation, e.g. earthquakes etc., and due to slow motions (creep) in the rock mass, e.g. orogenic events, 
loading-unloading of an ice-load, and plate motions. The result of the release of stress may be the formation 
of a fracture, and if movement occurs along the fracture, a fault. A more likely event is movement along 
already existing fractures and faults. 
Faulting may alter the rock permeability in the rock mass and alter or short-circuit the flow paths and flow 
distributions close to the repository and create new pathways through the repository. New or regenerated 
faults may enhance the groundwater flow, destabilise and damage engineered barriers, thus decreasing the 
transport times for potentially released radionuclides. etc. 
YMP PRIMARY FEP DESCRIPTION: Faulting may occur due to sudden major changes in the stress 
situation (e.g. seismic activity) or due to slow motions in the rock mass (e.g., tectonic activity). Movement 
along existing fractures and faults is more likely than the formation of new faults. Faulting may alter the rock 
permeability in the rock mass and alter or short-circuit the flow paths and flow distributions close to the 
repository and create new pathways through the repository. New faults or the Cavitation of existing faults 
may enhance the groundwater flow, thus decreasing the transport times for potentially released 
radionuclides.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VII-3 March 2000 
SECONDARY YMP FEP NUMBER: 1.2.02.02.01 
FEP NAME: Faulting 
ORIGINATOR FEP DESCRIPTION: Movement between adjacent rock masses, along a fracture, could result 
in changes hydraulic heads, groundwater flow and rock stresses. 
SECONDARY YMP FEP NUMBER: 1.2.02.02.02 
FEP NAME: Fault generation 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 1.2.02.02.03 
FEP NAME: Fault activation 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 1.2.02.02.04 
FEP NAME: Movements along small-scale faults 
ORIGINATOR FEP DESCRIPTION: A fraction of the deformation will be absorbed by minor faults such as 
the cataclastic zones intercepting emplacement tunnels. The displacement is likely to be the order of a few 
centimeters and not exceed 1 m in one million years. etc. 
SECONDARY YMP FEP NUMBER: 1.2.02.02.05 
FEP NAME: Faulting/fracturing 
ORIGINATOR FEP DESCRIPTION: Faults and fractures are the primary pathway for groundwater 
movement and, hence, radionuclide transport. Generation of new faults and reactivation of preexisting faults may 
significantly change the far-field transport paths. 
SECONDARY YMP FEP NUMBER: 1.2.02.02.06 
FEP NAME: Formation of new faults 
ORIGINATOR FEP DESCRIPTION: Faults are present in the Delaware Basin in both the units underlying 
the Salado and in the Permian evaporite sequence. According to Powers et al (1978,4-57), there is evidence that 
movement along faults within the pre Permian units affected the thickness of Early Permian strata, but these faults 
did not exert a structural control on the deposition of the Castile, the Salado, or the Rustler. etc. 
SECONDARY YMP FEP NUMBER: 1.2.02.02.07 
FEP NAME: Fault movement 
ORIGINATOR FEP DESCRIPTION: Faults are present in the Delaware Basin in both the units underlying 
the Salado and in the Permian evaporite sequence. According to Powers et al (1978,4-57), there is evidence that 
movement along faults within the pre-Permian units affected the thickness of Early Permian strata, but these faults 
did not exert a structural control on the deposition of the Castile, the Salado, or the Rustler. etc. 
SECONDARY YMP FEP NUMBER: 1.2.02.02.08 
FEP NAME: Normal faulting occurs or exists at Yucca Mountain 
ORIGINATOR FEP DESCRIPTION: Normal faulting occurs around Yucca Mtn or normal movement on 
existing normal faults occurs. 
SECONDARY YMP FEP NUMBER: 1.2.02.02.09 
FEP NAME: Strike/slip faulting occurs or exists at Yucca Mountain

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VII-4 March 2000 
ORIGINATOR FEP DESCRIPTION: Strike/slip faulting occurs around Yucca Mtn or strike/slip movement 
on existing faults occurs. 
SECONDARY YMP FEP NUMBER: 1.2.02.02.10 
FEP NAME: Detachment faulting occurs or exists at Yucca Mountain 
ORIGINATOR FEP DESCRIPTION: Detachment faulting occurs around Yucca Mtn or movement on 
existing listric faults occurs. 
SECONDARY YMP FEP NUMBER: 1.2.02.02.11 
FEP NAME: Dip/slip faulting occurs at Yucca Mountain 
ORIGINATOR FEP DESCRIPTION: Dip/slip faulting occurs around Yucca Mtn or dip/slip movement on 
existing faults occurs. 
SECONDARY YMP FEP NUMBER: 1.2.02.02.12 
FEP NAME: New fault occurs at Yucca Mountain 
ORIGINATOR FEP DESCRIPTION: A new fault develops through or near Yucca Mountain. 
SECONDARY YMP FEP NUMBER: 1.2.02.02.13 
FEP NAME: Old fault strand is reactivated at Yucca Mountain 
ORIGINATOR FEP DESCRIPTION: An old fault strand (e.g. H-5 Splay of Solitario Canyon fault) through 
or near Yucca Mountain is reactivated. 
SECONDARY YMP FEP NUMBER: 1.2.02.02.14 
FEP NAME: New fault strand is activated at Yucca Mountain 
ORIGINATOR FEP DESCRIPTION: A new fault strand develops from an existing fault through or near 
Yucca Mountain (e.g. a strand off Solitario Canyon fault, in the manner of the H-5 Splay). 
SECONDARY YMP FEP NUMBER: 1.2.02.02.15 
FEP NAME: Movements along major faults 
ORIGINATOR FEP DESCRIPTION: Movements along faults will occur due to the updoming of the 
Southern Black Forest and the existing compressive stress field in the crystalline basement resulting from the Alpine 
orogeny. The relative movement along any fault will lie in the range 0 to 100 m in one million years. 
SECONDARY YMP FEP NUMBER: 1.2.02.02.16 
FEP NAME: Faulting (large scale, in geosphere) 
ORIGINATOR FEP DESCRIPTION: Faulting may occur due to sudden changes in the stress situation, e.g. 
earthquakes, etc., and due to slow motions (creep) in the rockmass,e.g. orogenic events, loading-unloading of an ice 
load, and plate motions. The result is a fracture or if a movement occurs along the fracture, a fault. 
SECONDARY YMP FEP NUMBER: 1.2.02.02.17 
FEP NAME: Faulting (large scale, in geosphere) 
ORIGINATOR FEP DESCRIPTION: Faulting may occur due to sudden changes in the stress situation, e.g. 
earthquakes, etc., and due to slow motions (creep) in the rockmass,e.g. orogenic events, loading-unloading of an ice 
load, and plate motions. The result is a fracture or if a movement occurs along the fracture, a fault.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VII-5 March 2000 
PRIMARY YMP FEP NUMBER: 1.2.03.01.00 
FEP NAME: Seismic activity 
ORIGINATOR FEP DESCRIPTION: (Identified as "Earthquakes" by originator) 
Earthquakes could produce jointed-rock motion, rapid fault growth, slow fault growth or new fault 
formation, resulting in changes in hydraulic heads, changes in groundwater recharge or discharge zones, 
changes in rock stresses and severe disruption of the integrity of the vault. 
YMP PRIMARY FEP DESCRIPTION: Seismic activity (i.e., earthquakes) could produce jointed-rock 
motion, rapid fault growth, slow fault growth or new fault formation, resulting in changes in hydraulic heads, 
changes in groundwater recharge or discharge zones, changes in rock stresses, and severe disruption of the 
integrity of the drifts (e.g., vibration damage, rockfall). 
SECONDARY YMP FEP NUMBER: 1.2.03.01.01 
FEP NAME: Earthquakes 
ORIGINATOR FEP DESCRIPTION: Large earthquakes, vibration from many smaller earthquakes or related 
events such as movement of the crust or plate could affect all components of the vault. 
SECONDARY YMP FEP NUMBER: 1.2.03.01.02 
FEP NAME: Earthquakes 
ORIGINATOR FEP DESCRIPTION: Earthquakes could influence the containment of the nuclear fuel waste 
by opening or closing fractures in the geosphere. This may change the discharge of contaminants from the geosphere 
into the biosphere. 
SECONDARY YMP FEP NUMBER: 1.2.03.01.03 
FEP NAME: Earthquakes 
ORIGINATOR FEP DESCRIPTION: Earthquakes occur in Sweden. They are usually small, magnitude 0-4, 
but there are historic examples with earthquakes up to magnitude 6. etc. 
SECONDARY YMP FEP NUMBER: 1.2.03.01.04 
FEP NAME: Seismicity 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 1.2.03.01.05 
FEP NAME: Seismicity 
ORIGINATOR FEP DESCRIPTION: Seismic activity is low in the potential repository siting areas in 
Northern Switzerland and the corresponding risk to safety is considered negligible. Direct disturbance of a sealed 
repository by seismic activity can practically be ruled out. etc. 
SECONDARY YMP FEP NUMBER: 1.2.03.01.06 
FEP NAME: Seismicity 
ORIGINATOR FEP DESCRIPTION: Seismicity is the compressional and shear wave energy transmitted 
through the rock mass resulting naturally from the generation or reactivation of faults; it may also be induced due to 
stress-relief mechanisms in the near-field. 
SECONDARY YMP FEP NUMBER: 1.2.03.01.07 
FEP NAME: Seismic activity 
ORIGINATOR FEP DESCRIPTION: This FEP is concerned with the effects of seismic activity away from 
the immediate source region, and only the effects of groundshine and earthquakes are discussed.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VII-6 March 2000 
PRIMARY YMP FEP NUMBER: 1.2.04.02.00 
FEP NAME: Igneous activity causes changes to rock properties 
ORIGINATOR FEP DESCRIPTION: (Identified as "Igneous activity causes extreme changes to rock 
hydrologic properties" by originator) 
Igneous activity near the underground facility causes extreme changes to rock hydrologic properties. 
Permeabilities of dikes and sills and the heated regions immediately around them can differ from those of 
country rock. 
YMP PRIMARY FEP DESCRIPTION: Igneous activity near the underground facility causes extreme 
changes to rock hydrologic and mineralogic properties. Permeabilities of dikes and sills and the heated 
regions immediately around them can differ from those of country rock. Mineral alterations can also change 
the chemical response to contaminants. 
SECONDARY YMP FEP NUMBER: 1.2.04.02.01 
FEP NAME: Dike provides a permeable flow path 
ORIGINATOR FEP DESCRIPTION: A new dike develops well-connected cooling fractures and is more 
permeable than the surrounding rock. 
SECONDARY YMP FEP NUMBER: 1.2.04.02.02 
FEP NAME: Dike provides a barrier to flow 
ORIGINATOR FEP DESCRIPTION: A new dike is less permeable than the surrounding rock. 
SECONDARY YMP FEP NUMBER: 1.2.04.02.03 
FEP NAME: Volcanic activity in the vicinity produces an impoundment 
ORIGINATOR FEP DESCRIPTION: Volcanic activity in the vicinity of the site (e.g., lava flow) leads to 
damming of a wash or canyon that produces a large surface-water impoundment. Percolation flux is substantially 
increased beneath the impoundment and interacts with the repository. 
SECONDARY YMP FEP NUMBER: 1.2.04.02.04 
FEP NAME: Igneous activity causes extreme changes to rock geochemical properties 
ORIGINATOR FEP DESCRIPTION: Igneous activity near the underground facility causes extreme changes 
to rock mineralogic properties. Mineral alterations also change the chemical response to contaminants. 
SECONDARY YMP FEP NUMBER: 1.2.04.02.05 
FEP NAME: Intrusion (magmatic) 
ORIGINATOR FEP DESCRIPTION: Magmatism near the disposal facility could lead to substantial changes 
in existing groundwater flows and rock properties. 
SECONDARY YMP FEP NUMBER: 1.2.04.02.06 
FEP NAME: Dike related fractures alter flow 
ORIGINATOR FEP DESCRIPTION: The intrusion, either by emplacement or during cooling can produce a 
set of fractures in a zone adjacent to the dike, altering flow characteristics. 
SECONDARY YMP FEP NUMBER: 1.2.04.02.07 
FEP NAME: Magmatic activity

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VII-7 March 2000 
ORIGINATOR FEP DESCRIPTION: Magmatism could occur in the vicinity of the vault, leading to 
substantial changes to groundwater flow and rock properties. 
PRIMARY YMP FEP NUMBER: 1.2.06.00.00 
FEP NAME: Hydrothermal activity 
ORIGINATOR FEP DESCRIPTION: Hydrothermal activity refers to FEPs associated with high 
temperature groundwaters, including processes such as density-driven groundwater flow and hydrothermal 
alteration of minerals in the rocks through which the high temperature groundwater flows. 
YMP PRIMARY FEP DESCRIPTION: This category contains FEPs associated with naturally-occurring 
high-temperature groundwaters, including processes such as density-driven groundwater flow and 
hydrothermal alteration of minerals in the rocks through which the high temperature groundwater flows. 
SECONDARY YMP FEP NUMBER: 1.2.06.00.01 
FEP NAME: Hydrothermal activity 
ORIGINATOR FEP DESCRIPTION: A relationship between the increased geothermal gradient in Northern 
Switzerland and the Permo-Carboniferous Trough has been postulated on several occasions. The fault system at the 
margin of the trough appear to promote the rise of groundwaters. etc. 
PRIMARY YMP FEP NUMBER: 1.2.10.01.00 
FEP NAME: Hydrological response to seismic activity 
ORIGINATOR FEP DESCRIPTION: (Identified as "Hydrological response to earthquakes" by 
originator) 
There are a variety of hydrological responses to earthquakes. Some of these responses, such as changes to 
surface-water flow directions, result directly from fault movement. Others, such as changes in subsurface 
water chemistry and temperature, probably result from changes in flow pathways along the fault or fault 
zone. etc. 
YMP PRIMARY FEP DESCRIPTION: Seismic activity, associated with fault movement, may create new 
or enhanced flow pathways and/or connections between stratigraphic units, or it may change the stress (and 
therefore fluid pressure) within the rock. These responses have the potential to significantly change the 
surface- and groundwater flow directions, water level, water chemistry and temperature. 
SECONDARY YMP FEP NUMBER: 1.2.10.01.01 
FEP NAME: Fault movement pumps fluid from SZ to UZ (seismic pumping) 
ORIGINATOR FEP DESCRIPTION: Fault movement relieves stress (increased fluid pressure in pores and 
fractures) in the saturated zone by driving water up fractures in the unsaturated zone, thus raising the water table. 
SECONDARY YMP FEP NUMBER: 1.2.10.01.02 
FEP NAME: Fault creep causes short term fluctuations of the water table 
ORIGINATOR FEP DESCRIPTION: Fault creep includes minor restructuring of the in situ strain-energy 
field. This change causes short-term stress-induced fluctuations in the level of the water table. 
SECONDARY YMP FEP NUMBER: 1.2.10.01.03 
FEP NAME: New faulting breaches flow barrier controlling large hydraulic gradient to the north 
ORIGINATOR FEP DESCRIPTION: Fracturing along a new fault creates a permeable pathway through the 
flow barrier assumed to control the large hydraulic gradient and the water table rises to the top of the Calico Hills 
unit.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VII-8 March 2000 
SECONDARY YMP FEP NUMBER: 1.2.10.01.04 
FEP NAME: Normal faulting produces a trap for laterally moving moisture in the Tiva Canyon unit 
ORIGINATOR FEP DESCRIPTION: Normal faulting produces a trap intercepting laterally moving moisture 
in the Tiva Canyon unit and increases flux in the Topopah Spring units. 
SECONDARY YMP FEP NUMBER: 1.2.10.01.05 
FEP NAME: Head-driven flow up from Carbonates 
ORIGINATOR FEP DESCRIPTION: A fault connection of the EBS, UZ, and SZ allows water flow up the 
fault from the carbonates to the EBS. 
SECONDARY YMP FEP NUMBER: 1.2.10.01.06 
FEP NAME: Seismically-induced water table changes 
ORIGINATOR FEP DESCRIPTION: As a result of distant earthquakes, the local water table elevation 
changes. 
SECONDARY YMP FEP NUMBER: 1.2.10.01.07 
FEP NAME: Fault pathway through the altered Topopah Spring basal vitrophyre 
ORIGINATOR FEP DESCRIPTION: Movement along an old fault or creation of a new fault generates a 
pathway thru the altered Topopah Spring basal vitrophyre. 
SECONDARY YMP FEP NUMBER: 1.2.10.01.08 
FEP NAME: Fault movement connects tuff and carbonate aquifers 
ORIGINATOR FEP DESCRIPTION: A new fault or movement on an old fault establishes a connection 
between the tuff aquifers and the carbonate aquifers. 
SECONDARY YMP FEP NUMBER: 1.2.10.01.09 
FEP NAME: Fault establishes pathway through the UZ 
ORIGINATOR FEP DESCRIPTION: Movement along an old fault or creation of a new fault generates a 
pathway thru the UZ. 
SECONDARY YMP FEP NUMBER: 1.2.10.01.10 
FEP NAME: Fault establishes pathway through the SZ 
ORIGINATOR FEP DESCRIPTION: Movement along an old fault or creation of a new fault generates a flow 
path in the SZ. 
SECONDARY YMP FEP NUMBER: 1.2.10.01.11 
FEP NAME: Fluid supplied by a fault migrates down the drift 
ORIGINATOR FEP DESCRIPTION: A pathway established by fault movement through the repository brings 
fluid to the drift; fluid which migrates down the drift to transport contaminants down other pathways in the UZ. 
SECONDARY YMP FEP NUMBER: 1.2.10.01.12 
FEP NAME: Fault intersects and drains condensate zone 
ORIGINATOR FEP DESCRIPTION: Movement on a fault (new or old) intersects a condensate zone above 
the drifts and the fault drains the condensate into one or more drifts. 
SECONDARY YMP FEP NUMBER: 1.2.10.01.13 
FEP NAME: Flow barrier south of site blocks flow, causing water table to rise

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VII-9 March 2000 
ORIGINATOR FEP DESCRIPTION: As in YSCP15, fault-caused fracturing breaches the flow barrier north 
of the repository block. Flow is blocked by another barrier, not apparent from the current head distribution, and the 
resulting rise in water table floods the repository. Water passing through the repository discharges through springs in 
Forty mile Wash. 
PRIMARY YMP FEP NUMBER: 1.2.10.02.00 
FEP NAME: Hydrologic response to igneous activity 
ORIGINATOR FEP DESCRIPTION: (Identified as "Igneous intrusion causes water table to rise" by 
originator) An igneous intrusion produces a barrier to flow or drastically alters thermal conditions, causing 
the water table to rise. 
YMP PRIMARY FEP DESCRIPTION: Igneous activity may change the groundwater flow directions, 
water level, water chemistry and temperature. Igneous activity includes magmatic intrusions which may 
change rock properties and flow pathways, and thermal effects which may heat up groundwater and rock. 
SECONDARY YMP FEP NUMBER: 1.2.10.02.01 
FEP NAME: Interaction of WT with Magma 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 1.2.10.02.02 
FEP NAME: Interaction of UZ Pore Water with Magma 
ORIGINATOR FEP DESCRIPTION: Issues: heating, steam explosions. 
PRIMARY YMP FEP NUMBER: 2.2.06.02.00 
FEP NAME: Changes in stress (due to thermal, seismic, or tectonic effects) produce change in 
permeability of faults 
ORIGINATOR FEP DESCRIPTION: (Identified as "Alteration of permeability along and across faults 
due to changes in stress" by originator. Stress changes due to tectonic and seismic events alter the 
permeability along and across faults. 
YMP PRIMARY FEP DESCRIPTION: Stress changes due to thermal, tectonic and seismic processes result 
in strains that alter the permeability along and across faults. 
SECONDARY YMP FEP NUMBER: 2.2.06.02.01 
FEP NAME: Aseismic alteration of permeability along and across fault 
ORIGINATOR FEP DESCRIPTION: Aseismic stress changes due to tectonic events alter the permeability 
along and across faults. 
SECONDARY YMP FEP NUMBER: 2.2.06.02.02 
FEP NAME: Fracture dilation along faults creates zones of enhanced permeability 
ORIGINATOR FEP DESCRIPTION: Fracture dilation along faults creates zones of enhanced permeability in 
the Calico Hills and Paintbrush nonwelded units. Erosion of an arroyo at the surface and increased hydraulic 
conductivity of the Paintbrush unit create a zone of increased percolation along the fault. Moisture moves through 
fractures along the fault. 
SECONDARY YMP FEP NUMBER: 2.2.06.02.03 
FEP NAME: Relaxation of thermal stresses by fault movement

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VII-10 March 2000 
ORIGINATOR FEP DESCRIPTION: Thermo-mechanical stress buildup in the mountain may produce 
movement on adjacent faults. 
SECONDARY YMP FEP NUMBER: 2.2.06.02.04 
FEP NAME: Seismically-stimulated release of thermo-mechanical stress on bounding fault 
ORIGINATOR FEP DESCRIPTION: Thermo-mechanical stress accumulated as a result of repository heat is 
stimulated by seismic waves to be released on nearby faults. 
SECONDARY YMP FEP NUMBER: 2.2.06.02.05 
FEP NAME: Relaxation of thermal stresses by fault movement 
ORIGINATOR FEP DESCRIPTION: Thermo-mechanical stress buildup in the mountain may produce 
movement on adjacent faults. 
PRIMARY YMP FEP NUMBER: 2.2.06.03.00 
FEP NAME: Changes in stress (due to seismic or tectonic effects) alter perched water zones 
ORIGINATOR FEP DESCRIPTION: Identified as "Stress changes alter water budget of perched zones" 
by originator. Strain due to stress changes from tectonic and seismic events alter the permeabilities which 
allow formation of perched water zones. 
YMP PRIMARY FEP DESCRIPTION: Strain caused by stress changes from tectonic or seismic events 
alters the rock permeabilities that allow formation and persistence of perched water zones. 
SECONDARY YMP FEP NUMBER: 2.2.06.03.01 
FEP NAME: Perched zones develop as a result of stress changes 
ORIGINATOR FEP DESCRIPTION: Strain due to stress changes from tectonic and seismic events alter the 
permeabilities and allow development of perched water zones. 
PRIMARY YMP FEP NUMBER: 2.2.12.00.00 
FEP NAME: Undetected features (in geosphere) 
ORIGINATOR FEP DESCRIPTION: Undetected features refers to FEPs related to natural or man-made 
features within the geology that may not be detected during the site investigation. 
YMP PRIMARY FEP DESCRIPTION: This category contains FEPs related to undetected features in the 
geosphere that can affect long-term performance of the disposal system. Undetected but important features 
may be present, and have significant impacts. These features include unknown active fracture zones, 
inhomogeneities, faults and features connecting different zones of rock, different geometries for fracture 
zones and induced fractures due to the construction or presence of the repository. 
SECONDARY YMP FEP NUMBER: 2.2.12.00.01 
FEP NAME: Undetected dike beneath the repository passing thru the Calico Hills provides a highly permeable 
flow path 
ORIGINATOR FEP DESCRIPTION: An undetected dike passing through the Calico Hills nonwelded unit 
below the repository has a high fracture permeability and provides a rapid flow path. 
SECONDARY YMP FEP NUMBER: 2.2.12.00.02 
FEP NAME: Undetected fault dips below the repository providing a highly permeable flow path

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VII-11 March 2000 
ORIGINATOR FEP DESCRIPTION: An undetected major fault dips below the repository. The fault has 
greater permeability than surrounding unfaulted rock, and enhanced moisture flow along it passes through the Calico 
Hills nonwelded unit in fractures. 
SECONDARY YMP FEP NUMBER: 2.2.12.00.03 
FEP NAME: Undetected fault beneath the repository acts as a flow barrier altering the flow system 
ORIGINATOR FEP DESCRIPTION: An undetected major fault dips below the repository. Because of the 
formation of fault gouge, matrix hydraulic conductivity in the fault is less than the moisture flux, and so moisture 
flows through the Calico Hills nonwelded unit along fractures in or just above the fault. 
SECONDARY YMP FEP NUMBER: 2.2.12.00.04 
FEP NAME: Undetected fault connects tuff aquifers to carbonate aquifers; providing a fast path 
ORIGINATOR FEP DESCRIPTION: An undetected fault provides a path for water movement from the tuff 
aquifer beneath the western portion of the repository to an underlying carbonate aquifer. 
SECONDARY YMP FEP NUMBER: 2.2.12.00.05 
FEP NAME: Perched water escapes detection and waste is put in it 
ORIGINATOR FEP DESCRIPTION: A wet zone below a minor fault through the Tiva Canyon lower contact 
escapes detection during the repository construction, and waste is emplaced in it.. 
SECONDARY YMP FEP NUMBER: 2.2.12.00.06 
FEP NAME: Undiscovered mine shaft (an old prospect hole) in a wash acts as a source for increased local 
infiltration 
ORIGINATOR FEP DESCRIPTION: An old prospect in a wash retains water after floods and therefore is a 
source of enhanced infiltration. The wet zone beneath is not detected during repository construction, and waste is 
emplaced in it. 
SECONDARY YMP FEP NUMBER: 2.2.12.00.07 
FEP NAME: Rock properties-undetected features 
ORIGINATOR FEP DESCRIPTION: Undetected but important features may be present, and have significant 
impacts. These features include unknown active fracture zones, inhomogeneities, faults and features connecting 
different zones of rock, different geometries for fracture zones and induced fractures due to the construction or 
presence of the vault. 
SECONDARY YMP FEP NUMBER: 2.2.12.00.08 
FEP NAME: Undetected fracture zone 
ORIGINATOR FEP DESCRIPTION: Fracture zones are part of our conceptual model. It is not clear that 
possibly undetected features are dealt with in the "standard" sensitivity/uncertainty analysis. Undetected features can 
be analyzed by using the frequency of fracture zones from other sites. 
SECONDARY YMP FEP NUMBER: 2.2.12.00.09 
FEP NAME: Undetected features 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 2.2.12.00.10 
FEP NAME: Undetected past intrusions 
ORIGINATOR FEP DESCRIPTION: None.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VII-12 March 2000 
SECONDARY YMP FEP NUMBER: 2.2.12.00.11 
FEP NAME: Undetected discontinuities (in geosphere) 
ORIGINATOR FEP DESCRIPTION: Undetected discontinuities in the geosphere may affect performance.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VIII-1 March 2000 
ATTACHMENT VIII 
REPOSITORY PERTURBED THMC FEPS DESCRIPTIONS

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VIII-2 March 2000 
PRIMARY YMP FEP NUMBER: 1.1.02.00.00 
FEP NAME: Excavation/construction 
ORIGINATOR FEP DESCRIPTION: Excavation/construction refers to FEPs related to the excavation of 
shafts, tunnels, disposal galleries, silos etc. of a repository, the stabilization of these openings and 
installation/assembly of structural elements. 
YMP PRIMARY FEP DESCRIPTION: This category contains FEPs related to the excavation of the 
underground regions of the repository, and effects of this excavation on the long-term behavior of the 
engineered and natural barriers. Excavation-related effects include changes to rock properties due to boring 
and blasting and geochemical changes to rock and groundwater. 
SECONDARY YMP FEP NUMBER: 1.1.02.00.01 
FEP NAME: Blasting and vibration 
ORIGINATOR FEP DESCRIPTION: Blasting and vibration during construction of the vault (or afterwards) 
could substantially alter rock properties and water flow fields. 
SECONDARY YMP FEP NUMBER: 1.1.02.00.02 
FEP NAME: Geochemical alteration (excavation) 
ORIGINATOR FEP DESCRIPTION: Various geochemical alterations may occur during the desaturation and 
resaturation phases associated with excavation and backfilling in the EDZ. These are assumed to be insignificant in 
the assessment. 
SECONDARY YMP FEP NUMBER: 1.1.02.00.03 
FEP NAME: Groundwater chemistry (excavation) 
ORIGINATOR FEP DESCRIPTION: Various changes will occur in the porewater chemistry during the 
desaturation and resaturation phases associated with excavation, open period and backfilling. At present, no special 
assumptions are made for the composition of the EDZ groundwater. 
SECONDARY YMP FEP NUMBER: 1.1.02.00.04 
FEP NAME: Influx of oxidizing water 
ORIGINATOR FEP DESCRIPTION: Influx of oxidizing water through water-conducting features during the 
construction phase would alter their hydrochemistry and mineralogy. This is unlikely since groundwaters in the 
HPD and MWCF are also reducing. 
SECONDARY YMP FEP NUMBER: 1.1.02.00.05 
FEP NAME: Influx of oxidizing water 
ORIGINATOR FEP DESCRIPTION: Influx of oxidizing water through water-conducting features during the 
construction phase would alter their hydrochemistry and mineralogy. This is unlikely since groundwaters in the 
HPD and MWCF are also reducing.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VIII-3 March 2000 
PRIMARY YMP FEP NUMBER: 2.2.01.01.00 
FEP NAME: Excavation and construction-related changes in the adjacent host rock 
ORIGINATOR FEP DESCRIPTION: Identified as "Excavation-disturbed zone (EDZ)" by the originator. 
During tunnel and shaft construction, some stress relief, leading to dilation of joints and fractures, is expected 
in an axial zone of up to one diameter width surrounding the tunnels and shaft; this is termed the excavationdisturbed 
zone (EDZ). The characteristics and long-term importance of this zone are uncertain. etc. 
YMP PRIMARY FEP DESCRIPTION: Excavation will produce some disturbance of the rocks 
surrounding the drifts due to stress relief. Stresses associated directly with excavation (e.g., boring and 
blasting operations) may also cause some changes in rock properties. Properties that may be affected include 
rock strength, fracture spacing and block size, and hydrologic properties such as permeability. 
SECONDARY YMP FEP NUMBER: 2.2.01.01.01 
FEP NAME: Disturbed rock zone 
ORIGINATOR FEP DESCRIPTION: Construction of the repository has caused local excavation-induced 
changes in stress in the surrounding rock. This has led to failure of intact rock around the opening, creating a 
disturbed rock zone of fractures. etc. 
SECONDARY YMP FEP NUMBER: 2.2.01.01.02 
FEP NAME: Mechanical effects - Excavation/backfilling effects 
ORIGINATOR FEP DESCRIPTION: This FEP is redundant in the NEA database with J4.2.02.1 (entered in 
this database as 2.2.01e), and is retained here for completeness. 
SECONDARY YMP FEP NUMBER: 2.2.01.01.03 
FEP NAME: Formation of cracks (host rock disturbed zone) 
ORIGINATOR FEP DESCRIPTION: Cracks and faults could form or exist within or near the vault, affecting 
the performance of seals, grouts and the buffer. 
SECONDARY YMP FEP NUMBER: 2.2.01.01.04 
FEP NAME: Damaged zone (host rock disturbed zone) 
ORIGINATOR FEP DESCRIPTION: Enhanced groundwater flow and contaminant transport could occur 
within the zone of rock surrounding the shafts and vault that has been damaged during blasting or excavation. 
SECONDARY YMP FEP NUMBER: 2.2.01.01.05 
FEP NAME: Excavation/backfilling effects on nearby rock 
ORIGINATOR FEP DESCRIPTION: A potentially serious complicating factor for flow in crystalline rock is 
that the rock is deformable. Even small changes in the fracture openings cause large changes in permeability as the 
permeability is proportional to the aperture cubed. etc. 
SECONDARY YMP FEP NUMBER: 2.2.01.01.06 
FEP NAME: Mechanical effects - Excavation/backfilling effects 
ORIGINATOR FEP DESCRIPTION: This FEP is treated in Excavation/backfilling on nearby rock J4.2.2.1. 
SECONDARY YMP FEP NUMBER: 2.2.01.01.07 
FEP NAME: Enhanced rock fracturing 
ORIGINATOR FEP DESCRIPTION: Enhanced rock fracturing may be caused by excavation of repository 
through blasting and stress redistribution.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VIII-4 March 2000 
SECONDARY YMP FEP NUMBER: 2.2.01.01.08 
FEP NAME: Creeping of rock mass, near-field 
ORIGINATOR FEP DESCRIPTION: Creeping of rock mass occur in connection with excavation due to 
stress changes. These changes create an unstable situation in the rock mass close to the repository. However, this 
effect is probably of minor importance. 
SECONDARY YMP FEP NUMBER: 2.2.01.01.09 
FEP NAME: Excavation effects on nearby rock 
ORIGINATOR FEP DESCRIPTION: Excavating a repository in hard crystalline rock implies that there will 
be a volume of the rock that will be affected by the excavation, operation and sealing. The rock mass will be 
disturbed, it will be altered in an immediate and possibly time dependent way due to the excavation process (e.g. 
drilling, blasting) and by the stress redistribution resulting from removal of constraint around the system. 
SECONDARY YMP FEP NUMBER: 2.2.01.01.10 
FEP NAME: Disturbed zone (hydromechanical) effects 
ORIGINATOR FEP DESCRIPTION: The disturbed zone formed around the repository during construction 
may change the local hydrogeological system around the disposal vaults and access excavations. 
SECONDARY YMP FEP NUMBER: 2.2.01.01.11 
FEP NAME: Excavation-induced changes in stress 
ORIGINATOR FEP DESCRIPTION: Construction of the repository has caused local excavation-induced 
changes in stress in the surrounding rock. This has led to failure of intact rock around the opening, creating a 
disturbed rock zone of fractures. etc. 
PRIMARY YMP FEP NUMBER: 2.2.01.05.00 
FEP NAME: Radionuclide transport in excavation disturbed zone 
ORIGINATOR FEP DESCRIPTION: Identified as "Radionuclide migration (excavation disturbed 
zone)" by originator. Radionuclides emerging from the backfill can move advectively in open fissures in the 
decompressed zones, to reach the flow systems in the host rock. ... In assessment calculations, immediate 
transport from the bentonite periphery to water-conducting features in the host rock is assumed. 
YMP PRIMARY FEP DESCRIPTION: Radionuclide transport through the excavation disturbed zone may 
differ from transport in the waste and EBS and the undisturbed host rock. Transport processes such as 
dissolution and precipitation, sorption, and colloid filtration should be considered. 
SECONDARY YMP FEP NUMBER: 2.2.01.05.01 
FEP NAME: Radionuclide retardation (excavation-disturbed zone) 
ORIGINATOR FEP DESCRIPTION: Radionuclides transported from the bentonite through the EDZ to the 
far-field flow system may be retarded by sorption and matrix diffusion. 
SECONDARY YMP FEP NUMBER: 2.2.01.05.02 
FEP NAME: Radionuclide release from EDZ 
ORIGINATOR FEP DESCRIPTION: The radionuclides diffusing from the bentonite buffer to the EDZ are 
assumed to be transported immediately to transmissive elements in the host rock. The total release from the EDZ is 
taken to be the release from a single canister calculated by the STRENG model multiplied by the total number of 
canisters.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VIII-5 March 2000 
PRIMARY YMP FEP NUMBER: 2.2.07.10.00 
FEP NAME: Condensation zone forms around drifts 
ORIGINATOR FEP DESCRIPTION: Condensation of the 2-phase flow generated by repository heat 
forms in the rock where the temperature drops below the local vaporization temperature. 
YMP PRIMARY FEP DESCRIPTION: Condensation of the 2-phase flow generated by repository heat 
forms in the rock where the temperature drops below the local vaporization temperature. Waste package 
emplacement geometry and thermal loading will affect the scale at which condensation caps form (over waste 
packages, over panels, or over the entire repository), and the extent to which "shedding" will occur as water 
flows from the region above one drift to the region above another drift or into the rock between drifts. 
SECONDARY YMP FEP NUMBER: 2.2.07.10.01 
FEP NAME: Condensation cap forms above repository 
ORIGINATOR FEP DESCRIPTION: Water accumulates above the repository during the thermal period due 
to the "thermal barrier" created by evaporation and precipitation. 
SECONDARY YMP FEP NUMBER: 2.2.07.10.02 
FEP NAME: Formation of condensate over individual containers 
ORIGINATOR FEP DESCRIPTION: Condensate formed in the rock above the drift over individual 
containers. 
SECONDARY YMP FEP NUMBER: 2.2.07.10.03 
FEP NAME: Formation of condensate over individual panels 
ORIGINATOR FEP DESCRIPTION: Condensate formed in the rock above the drift over individual waste 
emplacement panels. 
SECONDARY YMP FEP NUMBER: 2.2.07.10.04 
FEP NAME: Formation of condensate over the entire repository 
ORIGINATOR FEP DESCRIPTION: Condensate formed in the rock above the drift over individual waste 
emplacement panels. 
SECONDARY YMP FEP NUMBER: 2.2.07.10.05 
FEP NAME: Shedding of condensation cap over one drift to another drift 
ORIGINATOR FEP DESCRIPTION: A condensate zone which forms over one drift during the thermal 
period, is redirected or shed to another adjacent drift. 
SECONDARY YMP FEP NUMBER: 2.2.07.10.06 
FEP NAME: Vault geometry 
ORIGINATOR FEP DESCRIPTION: Effects deriving from the complex 3-dimensional geometry of the vault 
may be important.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VIII-6 March 2000 
PRIMARY YMP FEP NUMBER: 2.2.07.11.00 
FEP NAME: Return flow from condensation cap / resaturation of dry-out zone 
ORIGINATOR FEP DESCRIPTION: During the thermal period, a condensation zone forms above the 
drifts - a condensation cap. When the rocks have cooled enough, there is a return flow toward the drifts from 
the condensation cap as a plume of unsaturated flow. 
YMP PRIMARY FEP DESCRIPTION: Following the peak thermal period, water in the condensation cap 
(see FEP 2.2.07.10.00) may flow downward into the drifts. Influx of cooler water from above, such as might 
occur from episodic flow, may accelerate return flow from the condensation cap by lowering temperatures 
below the condensation point. Percolating groundwater (distinct from water mobilized from the condensation 
cap) will also contribute to resaturation of the dry out zone. Vapor flow, as distinct from liquid flow by 
capillary processes, may also contribute. Water chemistry in the resaturation period may be affected by 
processes in the condensation cap and dry-out zone. 
SECONDARY YMP FEP NUMBER: 2.2.07.11.01 
FEP NAME: Auto-catalytic drainage of locally saturated flow thru condensation cap 
ORIGINATOR FEP DESCRIPTION: Penetration of episodic flow down a fracture cools the surrounding rock 
below the vaporization temperature so that flow from the condensation cap can penetrate further, eventually 
reaching the waste and passing through the repository. 
SECONDARY YMP FEP NUMBER: 2.2.07.11.02 
FEP NAME: Resaturation, near-field rock 
ORIGINATOR FEP DESCRIPTION: During the resaturation (and sealing) of the repository, flow directions 
are different and the hydraulic conductivity is different due to, for example, partially saturated fractures. 
Furthermore, (or especially) the groundwater chemistry is very different (oxidizing conditions exist). 
SECONDARY YMP FEP NUMBER: 2.2.07.11.03 
FEP NAME: Return of condensate to same panel 
ORIGINATOR FEP DESCRIPTION: Condensate formed in the rock above the drift returns to the same panel 
through fractures (during the thermal period) or through the matrix (post-thermal). 
SECONDARY YMP FEP NUMBER: 2.2.07.11.04 
FEP NAME: Resaturation of dry-out zone is affected by vapor flow 
ORIGINATOR FEP DESCRIPTION: The dry-out zone, the zone where the water content of the rock has 
been reduced by evaporation and 2-phase flow induced by repository heat, receives replacement water by transport 
of vapor from the water table and from surrounding country rock. 
SECONDARY YMP FEP NUMBER: 2.2.07.11.05 
FEP NAME: Resaturation of dry-out zone is effected by liquid under capillary forces 
ORIGINATOR FEP DESCRIPTION: Liquid water returns by capillarity to the dryout zone (in the UZ) 
around the drifts as the rock cools below the vaporization temperature. 
SECONDARY YMP FEP NUMBER: 2.2.07.11.06 
FEP NAME: Unsaturated flow plume returns flow from the condensation cap 
ORIGINATOR FEP DESCRIPTION: During the thermal period, a condensation zone - the condensation cap 
- forms above the drifts. When the rock has cooled the condensate returns to the rocks around the drifts and to the 
drifts as unsaturated flow, since the cap is heterogeneous, as an unsaturated flow plume.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VIII-7 March 2000 
PRIMARY YMP FEP NUMBER: 2.2.08.01.00 
FEP NAME: Groundwater chemistry / composition in UZ and SZ 
ORIGINATOR FEP DESCRIPTION: Identified as "groundwater chemistry" by originator. 
Refers to the groundwater chemistry in the geosphere (far-field rock) as well as changes in groundwater 
composition. The groundwater chemistry is dependent on the rock mineralogy through rock-water 
interactions and on other processes occurring in the groundwater, but also on interactions with other waters 
e.g. near-field waters, surface waters and saline waters. (SKI) 
YMP PRIMARY FEP DESCRIPTION: Chemistry and and other characteristics of groundwater in the 
saturated and unsaturated zones may affect groundwater flow and radionuclide transport. Groundwater 
chemistry and other characteristics, including temperature, pH, Eh, ionic strength, and major ionic 
concentrations, may vary spatially throughout the system as a result of different rock mineralogy, and may 
also change through time, as a result of the evolution of the disposal system or from mixing with other waters. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.01 
FEP NAME: Groundwater chemistry (in geosphere) 
ORIGINATOR FEP DESCRIPTION: The groundwater chemistry is controlled by a range of factors, 
including the rock mineralogy, recharge conditions and residence time. ... For repository performance, the most 
important chemical parameters are the ionic strength, the pH and the Eh. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.02 
FEP NAME: Deep saline water intrusion 
ORIGINATOR FEP DESCRIPTION: Saline water is often present at repository depth and at larger depths. 
Changes in groundwater salinity will influence chemical equilibria, and salinity gradients may be of importance. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.03 
FEP NAME: Interface different waters (in geosphere) 
ORIGINATOR FEP DESCRIPTION: Concerns the potential establishment of sharp interfaces between 
waters with different chemical composition, e.g. pH, salinity and redox conditions. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.04 
FEP NAME: Water chemistry in near-field rock 
ORIGINATOR FEP DESCRIPTION: Concerns the chemistry of the water in the rock surrounding the 
canister deposition holes and the tunnels in terms of the concentration of species which influence fracture properties 
and the speciation of radionuclides, as well as pH, redox and chemical gradients. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.05 
FEP NAME: Groundwater geochemistry (in geosphere) 
ORIGINATOR FEP DESCRIPTION: The most important aspect of groundwater geochemistry in the region 
of the WIP in terms of chemical retardation and colloid stability is salinity. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.06 
FEP NAME: Saline intrusion (in geosphere) 
ORIGINATOR FEP DESCRIPTION: Natural changes in the groundwater chemistry of the Culebra and other 
units that resulted from saline intrusion could potentially affect chemical retardation and the stability of colloids. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.07 
FEP NAME: Freshwater intrusion (in geosphere)

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VIII-8 March 2000 
ORIGINATOR FEP DESCRIPTION: Natural changes in the groundwater chemistry of the Culebra and other 
units that resulted from freshwater intrusion could potentially affect chemical retardation and the stability of 
colloids. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.08 
FEP NAME: Changes in groundwater Eh 
ORIGINATOR FEP DESCRIPTION: Natural changes in the groundwater chemistry of the Culebra and other 
units could potentially affect chemical retardation and the stability of colloids. Changes in groundwater Eh could 
also affect the migration of radionuclides. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.09 
FEP NAME: Changes in groundwater pH 
ORIGINATOR FEP DESCRIPTION: Natural changes in the groundwater chemistry of the Culebra and other 
units could potentially affect chemical retardation and the stability of colloids. Changes in groundwater pH could 
also affect the migration of radionuclides. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.10 
FEP NAME: Oxidizing conditions 
ORIGINATOR FEP DESCRIPTION: This is evidently a special case of redox conditions in general. It might 
be limited in space and time (e.g. when considering redox fronts), or it might apply to all of the migration path 
through the geosphere. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.11 
FEP NAME: Groundwater composition 
ORIGINATOR FEP DESCRIPTION: Groundwater compositions, including changes due to activities such as 
construction of dams and pollution, could affect groundwater flow regimes; complexing agents could affect 
transport and dissolution of minerals and contaminants. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.12 
FEP NAME: pH-deviations 
ORIGINATOR FEP DESCRIPTION: It is perfectly clear that the pH value might vary considerably due to 
"natural" reasons within a repository and the geosphere. In Swedish bedrock the outer limits of this variation is set 
by the buffering action of minerals and dissolved carbonates, e.g. about pH 6.5-10.5. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.13 
FEP NAME: Change of groundwater chemistry in nearby rock 
ORIGINATOR FEP DESCRIPTION: The presence of construction, backfill and other man-made materials 
will cause changes of the geochemistry in the near-field. Another source of such changes is the formation of 
radiolysis products. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.14 
FEP NAME: Saline (or fresh) groundwater intrusion 
ORIGINATOR FEP DESCRIPTION: Saline water is often present at repository depths. Change in 
groundwater salinity will influence chemical equilibria, and salinity gradients might be of importance for 
groundwater flow. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.15 
FEP NAME: Saline or freshwater intrusion

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ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.16 
FEP NAME: Effects at saline-freshwater interface 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.17 
FEP NAME: Chemical gradientsrface 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.18 
FEP NAME: Non-radioactive solute plume in geosphere 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.19 
FEP NAME: Groundwater chemistry (in geosphere) 
ORIGINATOR FEP DESCRIPTION: The groundwater chemistry is controlled by a range of factors, 
including the rock mineralogy, recharge conditions and residence time. ... The groundwater chemistry of the LPD is 
assumed to be unperturbed by the presence of the repository. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.20 
FEP NAME: Intrusion of saline groundwater 
ORIGINATOR FEP DESCRIPTION: Saline waters are found in the sedimentary units overlying the 
crystalline basement, in the Permo-Carboniferous Trough and, at a small number of sampling points, in the 
crystalline basement itself. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.21 
FEP NAME: Groundwater conditions 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.22 
FEP NAME: Mineralogy (host rock) 
ORIGINATOR FEP DESCRIPTION: The mineralogy of the LPD is heterogeneous. The average mineralogy 
of the water-conducting features differs from that of the undisturbed rock. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.01.23 
FEP NAME: Mineralogy (host rock) 
ORIGINATOR FEP DESCRIPTION: The mineralogy of the Major Water-Conducting Faults is 
heterogeneous. The average mineralogy of the water-conducting features differs from that of the surrounding rock.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VIII-10 March 2000 
PRIMARY YMP FEP NUMBER: 2.2.08.02.00 
FEP NAME: Radionuclide transport occurs in a carrier plume in geosphere 
ORIGINATOR FEP DESCRIPTION: Identified as "Solute transport occurs in a carrier plume" by 
originator. Radionuclides are dissolved into the carrier plume (see 2.1.09k, 2.1.11h). 
YMP PRIMARY FEP DESCRIPTION: Radionuclide transport occurs in a carrier plume in the geosphere. 
Transport may be as dissolved or colloidal species, and transport may occur in both the unsaturated and 
saturated zone. See also FEPs 2.1.09.01.00 (carrier plume forms in waste and EBS), 2.2.08.01.00 
(groundwater chemistry / composition) and 2.2.08.03.00 (geochemical interactions). 
SECONDARY YMP FEP NUMBER: 2.2.08.02.01 
FEP NAME: Locally-saturated carrier plume forms (in geosphere) 
ORIGINATOR FEP DESCRIPTION: When the flow system reestablishes itself through the repository, it is 
likely to do so before contaminants are mobile. This reestablished flow system, which can be a locally saturated 
system (fracture flow) carries the signature of the repository (pH, temperature, dissolved constituents, etc.) is termed 
the carrier plume. 
SECONDARY YMP FEP NUMBER: 2.2.08.02.02 
FEP NAME: Unsaturated carrier plume forms (in geosphere) 
ORIGINATOR FEP DESCRIPTION: When the flow system reestablishes itself through the repository, it is 
likely to do so before contaminants are mobile. This reestablished flow system, which can be a UZ flow system, 
carries the signature of the repository (pH, temperature, dissolved constituents, etc.) is termed the carrier plume. 
SECONDARY YMP FEP NUMBER: 2.2.08.02.03 
FEP NAME: Precipitation/dissolution (release/migration factors) 
ORIGINATOR FEP DESCRIPTION: Refers to the precipitation and dissolution of elements previously 
released from the fuel. This may occur as a consequence of changes in water chemistry. etc. 
PRIMARY YMP FEP NUMBER: 2.2.08.03.00 
FEP NAME: Geochemical interactions in geosphere (dissolution, precipitation, weathering) and effects on 
radionuclide transport 
ORIGINATOR FEP DESCRIPTION: Geochemical interactions may lead to dissolution and precipitation 
of minerals along the groundwater flow path, affecting groundwater flow, rock properties and sorption on 
contaminants. 
YMP PRIMARY FEP DESCRIPTION: Geochemical interactions may lead to dissolution and precipitation 
of minerals along the groundwater flow path, affecting groundwater flow, rock properties and sorption on 
contaminants. These interactions may result from the evolution of disposal system or from external processes 
such as weathering. Effects on hydrologic flow properties of the rock, radionuclide solubilities, sorption 
processes, and colloidal transport are relevant. Kinetics of chemical reactions should be considered in the 
context of the time-scale of concern. See also FEP 2.2.08.01.00 for a discussion of groundwater chemistry and 
composition, FEP 2.2.08.07.00 for a discussion of solubility limits in the geosphere, FEP 2.2.08.09.00 for a 
discussion of sorption in the geosphere, and FEPs 2.2.08.10.00 and 2.2.08.10.01 for a discussion of colloidal 
transport . 
SECONDARY YMP FEP NUMBER: 2.2.08.03.01 
FEP NAME: Far-field transport: Changes in groundwater chemistry and flow direction 
ORIGINATOR FEP DESCRIPTION: It is inevitable that over the lifetime of the repository the groundwater 
chemistry and flow direction will change, e.g. due to changing recharge during glacial conditions. These changes

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VIII-11 March 2000 
may alter the sorption and desorption processes that occur on solid surfaces and may increase or decrease the 
sorptive capacity of the far-field rocks. 
SECONDARY YMP FEP NUMBER: 2.2.08.03.02 
FEP NAME: Effects of dissolution (in geosphere) 
ORIGINATOR FEP DESCRIPTION: Natural changes in the groundwater chemistry of the Culebra and other 
units could potentially affect chemical retardation and the stability of colloids. The magnitude of any natural 
temporal variation due to the effects of dissolution on groundwater chemistry is likely to be no greater than the 
present spatial variation. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.03.03 
FEP NAME: Rock property changes (in geosphere) 
ORIGINATOR FEP DESCRIPTION: Changes in the porosity and permeability properties of the rock due to 
processes may alter the groundwater flow-field and, thus, radionuclide transport in the far-field. ... The only rock 
property changes that are important to consider in the far-field are increases and decreases in permeability and a 
number of processes mat occur that affect these properties of the rock mass. 
SECONDARY YMP FEP NUMBER: 2.2.08.03.04 
FEP NAME: Hydraulic properties-evolution 
ORIGINATOR FEP DESCRIPTION: The precipitation and dissolution of material could affect the 
groundwater flow regime by plugging or opening pores and fractures. This process could be enhanced by differential 
solubilities in a thermal gradient. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.03.05 
FEP NAME: Dissolution of fracture fillings/precipitations (in geosphere) 
ORIGINATOR FEP DESCRIPTION: Fracture fillings are dissolved by groundwater for whatever unspecified 
reasons (e.g. temperature change). 
SECONDARY YMP FEP NUMBER: 2.2.08.03.06 
FEP NAME: Weathering of flow paths (in geosphere) 
ORIGINATOR FEP DESCRIPTION: Ongoing chemical reactions between groundwater and rock and 
fracture minerals lead to more or less continuous changes of the solid phases along the flow paths from a repository. 
Thus, not only weathering of rock minerals take place, but also healing of existing and newly formed fractures. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.03.07 
FEP NAME: Fracture mineralization and weathering (in geosphere) 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 2.2.08.03.08 
FEP NAME: Alteration/weathering of flow paths 
ORIGINATOR FEP DESCRIPTION: Ongoing chemical reactions between groundwater and rock- and 
fracture minerals lead to more or less continuous changes of the solid phases along the flow paths from a repository. 
Thus, not only weathering of rock minerals takes place, but also healing of existing and newly formed fractures. 
SECONDARY YMP FEP NUMBER: 2.2.08.03.09 
FEP NAME: Precipitation and dissolution (release/migration factors)

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ANL-NBS-MD-000001 REV 00 VIII-12 March 2000 
ORIGINATOR FEP DESCRIPTION: Contaminants, primary minerals and rock alteration products could be 
subjected to precipitation and dissolution at different points along their flow paths, due to changes in temperature 
(thermal gradients), groundwater chemistry, flow rates and mineralogy or the presence of microbes. 
SECONDARY YMP FEP NUMBER: 2.2.08.03.10 
FEP NAME: Chemical precipitation (release/migration factors) 
ORIGINATOR FEP DESCRIPTION: An important determinant in the transfer of contaminants in the 
environment is mobility. Highly mobile contaminants tend to reach humans and other organisms, and increase 
radiation exposure. Chemical precipitation in surface water, wetlands and soils tends to reduce mobility and thereby 
doses. 
SECONDARY YMP FEP NUMBER: 2.2.08.03.11 
FEP NAME: Dissolution, precipitation and crystallization (release/migration factors) 
ORIGINATOR FEP DESCRIPTION: None. 
SECONDARY YMP FEP NUMBER: 2.2.08.03.12 
FEP NAME: Kinetics of precipitation and dissolution (release/migration factors) 
ORIGINATOR FEP DESCRIPTION: At low temperatures, precipitation and dissolution reactions are caused 
by changes in fluid chemistry that result in chemical undersaturation or oversaturation (Bruno and Sandino 1987). 
SECONDARY YMP FEP NUMBER: 2.2.08.03.13 
FEP NAME: Speciation (contaminant speciation and solubility) 
ORIGINATOR FEP DESCRIPTION: Chemical speciation will affect dissolution and precipitation, and 
change with time following the thermal pulse. 
SECONDARY YMP FEP NUMBER: 2.2.08.03.14 
FEP NAME: Speciation (geosphere) (contaminant speciation and solubility) 
ORIGINATOR FEP DESCRIPTION: Speciation of contaminants in waters containing different inorganic and 
organic components will affect mobility and sorption. 
SECONDARY YMP FEP NUMBER: 2.2.08.03.15 
FEP NAME: Recrystallization (contaminant speciation and solubility) 
ORIGINATOR FEP DESCRIPTION: Recrystallization is linked to solubility phenomena and changes to 
water chemistry, in turn coupled to radiolysis. Recrystallization may also refer to the long-term alteration of a 
cement matrix, i.e. crystallization of calcium silicate hydrates. 
SECONDARY YMP FEP NUMBER: 2.2.08.03.16 
FEP NAME: Speciation (contaminant speciation and solubility) 
ORIGINATOR FEP DESCRIPTION: Radionuclide behavior will be determined by the physio-chemical 
matrix or form in which the radionuclide is incorporated, or speciation if in aqueous solution. 
SECONDARY YMP FEP NUMBER: 2.2.08.03.17 
FEP NAME: Kinetics of speciation (contaminant speciation and solubility) 
ORIGINATOR FEP DESCRIPTION: The effects of reaction kinetics in aqueous systems are discussed by 
Lasaga et al (1994) who suggest that in contrast to many heterogeneous reactions, homogeneous aqueous 
geochemical speciation reactions involving relatively small inorganic species occur rapidly and are accurately 
described by thermodynamic equilibrium models that neglect explicit consideration of reaction kinetics.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VIII-13 March 2000 
SECONDARY YMP FEP NUMBER: 2.2.08.03.18 
FEP NAME: Groundwater chemistry (sorption/desorption processes) 
ORIGINATOR FEP DESCRIPTION: The groundwater chemistry is controlled by a range of factors, 
including the rock mineralogy, recharge conditions and residence time. For repository performance, the most 
important chemical parameters are the ionic strength, the pH and the Eh. etc. 
PRIMARY YMP FEP NUMBER: 2.2.08.05.00 
FEP NAME: Osmotic processes 
ORIGINATOR FEP DESCRIPTION: Under appropriate circumstances, osmotic processes may occur at 
interfaces between waters of different salinities. Osmosis is the process by which water (or any solvent) 
diffuses through a semi-permeable (or differentially permeable) membrane in response to a concentration 
gradient. At WIPP, clay layers may act as semi-permeable membranes across which osmotic processes may 
occur. 
YMP PRIMARY FEP DESCRIPTION: Osmotic processes in response to chemical gradients could affect 
radionuclide transport in the geosphere. See also FEP 2.2.08.08.00, matrix diffusion. 
SECONDARY YMP FEP NUMBER: None 
FEP NAME: None 
ORIGINATOR FEP DESCRIPTION: None. 
PRIMARY YMP FEP NUMBER: 2.2.08.06.00 
FEP NAME: Complexation in geosphere 
ORIGINATOR FEP DESCRIPTION: (Identified as "Complexing agents" by originator) 
The presence of naturally occurring complexing agents is well established even for deep groundwaters, e.g. 
those deriving from humic and fulvic acids. Thus, their effect on barrier performance should be included in 
the process system. etc. 
YMP PRIMARY FEP DESCRIPTION: Complexing agents such as humic and fulvic acids present in 
natural groundwaters could affect radionuclide transport. See also FEP 2.1.09.13.00 for a discussion of 
complexing agents in the waste and EBS. 
SECONDARY YMP FEP NUMBER: None 
FEP NAME: None 
ORIGINATOR FEP DESCRIPTION: None.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VIII-14 March 2000 
PRIMARY YMP FEP NUMBER: 2.2.08.07.00 
FEP NAME: Radionuclide solubility limits in the geosphere 
ORIGINATOR FEP DESCRIPTION: Identified as "Far-field transport: Solubility constraints" by 
originator. The solubility of radionuclides is controlled by a number of factors, notably pH and Eh. The farfield 
chemistry is less perturbed by the presence of the repository than the near-field chemistry and, 
consequently, solubility constraints in the far-field can be less significant. However, the alkaline plume 
migrating from the near-field may cause significant perturbation in far-field chemistry and control 
radionuclide solubilities there. 
YMP PRIMARY FEP DESCRIPTION: Solubility limits for radionuclides may different in geosphere 
groundwater than in the water in the waste and EBS. See also FEP 2.2.08.01.00 for a discussion of 
groundwater chemistry and FEP 2.1.09.04.00 for a discussion of solubility limits in the waste and EBS. 
SECONDARY YMP FEP NUMBER: 2.2.08.07.01 
FEP NAME: Radionuclide transport through LPD (water transport) 
ORIGINATOR FEP DESCRIPTION: Solubility limits appropriate to the groundwater chemistry are not 
expected to be exceeded and so radionuclides in the LPD would exist either in solution in pores within the rock or 
sorbed onto solid surfaces. 
SECONDARY YMP FEP NUMBER: 2.2.08.07.02 
FEP NAME: Radionuclide transport through MWCF (water transport) 
ORIGINATOR FEP DESCRIPTION: Solubility limits appropriate to the groundwater chemistry are not 
expected to be exceeded and so radionuclides in the Major Water-Conducting Faults would exist either in solution in 
pores within the rock or sorbed onto solid surfaces. In pores through which groundwater flow occurs, predominantly 
the open channels of the small-scale water-conducting features, radionuclides in solution would be transported by 
advection. etc. 
SECONDARY YMP FEP NUMBER: 2.2.08.07.03 
FEP NAME: Solubility limits/colloid formation 
ORIGINATOR FEP DESCRIPTION: Solubility limits are unlikely to be reached in the far field except for 
naturally occurring nuclides, e.g. uranium isotopes. 
SECONDARY YMP FEP NUMBER: 2.2.08.07.04 
FEP NAME: Solubility limits/colloid formation 
ORIGINATOR FEP DESCRIPTION: Solubility limits are unlikely to be reached in the far field except for 
naturally occurring nuclides, e.g. uranium isotopes. 
PRIMARY YMP FEP NUMBER: 2.2.09.01.00 
FEP NAME: Microbial activity in geosphere 
ORIGINATOR FEP DESCRIPTION: Identified as "Microbial activity" by originator. 
Microbes will be naturally present in the system, but in low numbers due to low nutrient and energy 
availability. They may have a minor effect on radionuclide mobility that is small within the uncertainties in 
physical/chemical transport processes. 
YMP PRIMARY FEP DESCRIPTION: Microbial activity in the geosphere may affect radionuclide 
mobility in rock and soil through colloidal processes, by influencing the availability of complexing agents, or 
by influencing groundwater chemistry. See also FEP 2.2.08.10.00 for a discussion of colloidal transport and 
2.2.08.06.00 for a discussion of complexing agents.

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SECONDARY YMP FEP NUMBER: 2.2.09.01.01 
FEP NAME: Microbes (in geosphere) 
ORIGINATOR FEP DESCRIPTION: Incorporation of contaminants into or onto microbes or bacteria could 
affect the rate of transport of contaminants. The activity of microorganisms could affect the mobility of 
contaminants by methylating heavy metals, releasing organic ligands with a high complexing capacity, affecting the 
groundwater pH and redox, and reducing permeability in fractures. 
SECONDARY YMP FEP NUMBER: 2.2.09.01.02 
FEP NAME: Microbes (in geosphere) 
ORIGINATOR FEP DESCRIPTION: Microorganisms exist in geologic environments. ... Possible adverse 
consequences of microbial activities are production of corrosive agents and gases. Either the microbes themselves or 
substances produced by the microbes can be imagined to take up radionuclides by sorption or complex formation. 
SECONDARY YMP FEP NUMBER: 2.2.09.01.03 
FEP NAME: Microbial activity (in geosphere) 
ORIGINATOR FEP DESCRIPTION: Microbes will be naturally present in the system, but in low numbers 
due to low nutrient and energy availability. They may have a minor effect on radionuclide mobility that is small 
within the uncertainties in physical/chemical transport processes. 
SECONDARY YMP FEP NUMBER: 2.2.09.01.04 
FEP NAME: Far-field transport: Biogeochemical changes 
ORIGINATOR FEP DESCRIPTION: The surface environment will change over the lifetime of the repository 
due to changes in climate. The biological (microbial) load of recharge water may also change and this could affect 
the transport of radionuclides in the field. 
SECONDARY YMP FEP NUMBER: 2.2.09.01.05 
FEP NAME: Bacteria and microbes in soil 
ORIGINATOR FEP DESCRIPTION: These organisms help to decompose organic matter in the soil and 
liberate contaminants, which may then be leached or recycled. Bacteria and microbes may also chemically transform 
contaminants and thereby change their mobility in the environment. 
SECONDARY YMP FEP NUMBER: 2.2.09.01.06 
FEP NAME: Chemical transformations (biological processes) 
ORIGINATOR FEP DESCRIPTION: None. 
PRIMARY YMP FEP NUMBER: 2.2.10.01.00 
FEP NAME: Repository-induced thermal effects in geosphere 
ORIGINATOR FEP DESCRIPTION: None. 
YMP PRIMARY FEP DESCRIPTION: Thermal effects in the geosphere could affect the long-term 
performance of the disposal system. Thermal effects are most important in waste, engineered barrier system, 
and the disturbed zone surrounding the excavation. See FEPs 2.1.11.00.00 and 2.2.01.00.00 for discussions of 
this region. See other FEPs in this section for specific discussions of thermal effects in geosphere, including 
effects on saturated and unsaturated groundwater flow, mechanical properties, and chemical effects. 
SECONDARY YMP FEP NUMBER: 2.2.10.01.01 
FEP NAME: Temperature, far-field

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ORIGINATOR FEP DESCRIPTION: The temperature in the far-field rock depends on the location and depth 
of the repository and on the thermal properties of the rock and the groundwater. [The point of the FEP is that farfield 
temperature affects stress, groundwater flow, water chemistry, weathering of rocks, diffusion, thermal 
properties, etc. 
SECONDARY YMP FEP NUMBER: 2.2.10.01.02 
FEP NAME: Temperature, near-field rock 
ORIGINATOR FEP DESCRIPTION: The location and depth of the repository will affect the temperature in 
the surrounding rock, but the temperature in the nearby rock will also be affected by the ventilation of the repository 
during construction and operation. 
SECONDARY YMP FEP NUMBER: 2.2.10.01.03 
FEP NAME: Thermal effects on groundwater flow 
ORIGINATOR FEP DESCRIPTION: The geothermal gradient in the region of the WIPP has been measured 
at about 50 C per mile (30 C per km). Given the low permeability in the region, and the limited thickness of units in 
which groundwater flow occurs (for example the Culebra), natural convection will be too weak to have a significant 
effect on groundwater flow. etc. 
SECONDARY YMP FEP NUMBER: 2.2.10.01.04 
FEP NAME: Groundwater - evolution 
ORIGINATOR FEP DESCRIPTION: Groundwater compositions will evolve, due to the presence of the vault 
as a heat source. 
SECONDARY YMP FEP NUMBER: 2.2.10.01.05 
FEP NAME: Thermal effects on material properties (in waste and EBS) 
ORIGINATOR FEP DESCRIPTION: Potentially, thermal effects on material properties (such as permeability 
and porosity) could affect the behavior of the repository. 
SECONDARY YMP FEP NUMBER: 2.2.10.01.06 
FEP NAME: Thermal effects: Rock-mass changes 
ORIGINATOR FEP DESCRIPTION: The thermal pulse generated in the intermediate-level waste will cause 
the near-field rock to heat up possibly changing its physical properties, which in turn could affect radionuclide 
transport in the far-field. 
SECONDARY YMP FEP NUMBER: 2.2.10.01.07 
FEP NAME: Thermal effects: Hydrogeological changes 
ORIGINATOR FEP DESCRIPTION: The thermal pulse generated in the intermediate-level waste may cause 
the groundwater flow paths to change direction due to the existence of buoyancy forces. The thermal pulse is 
believed to be sufficient to perturb the groundwater flow paths in the far-field. etc.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VIII-17 March 2000 
PRIMARY YMP FEP NUMBER: 2.2.10.04.00 
FEP NAME: Thermo-mechanical alteration of fractures near repository 
ORIGINATOR FEP DESCRIPTION: Identified as "Thermo-mechanical alteration of stress-state in rock 
surrounding drifts" by originator. Heat from the waste causes thermal expansion of the surrounding rock, 
generating compressive stresses near the drifts and extensional stresses away from them. The zone of 
compression migrates with time. 
YMP PRIMARY FEP DESCRIPTION: Heat from the waste causes thermal expansion of the surrounding 
rock, generating changes in the stress field that may change the material properties (both hydrologic and 
mechanical) of fractures in the rock. Cooling following the peak thermal period will also change the stress 
field, further affecting rock properties near the repository. 
SECONDARY YMP FEP NUMBER: 2.2.10.04.01 
FEP NAME: Thermal expansion closes most fractures close to repository 
ORIGINATOR FEP DESCRIPTION: Thermal expansion closes most fractures near the repository. 
Preexisting fracture percolation is diverted into fractures of larger aperture. 
SECONDARY YMP FEP NUMBER: 2.2.10.04.02 
FEP NAME: Thermally-induced fracturing around containers creates a capillary barrier 
ORIGINATOR FEP DESCRIPTION: Thermally induced fracturing of rocks immediately surrounding waste 
canisters creates capillary barriers to movement of moisture between blocks of rock matrix. The matrix is locally 
saturated, forcing flow out into the fractures and resulting in film flow or droplet impact on waste packages. The 
result is accelerated localized corrosion and waste dissolution. 
SECONDARY YMP FEP NUMBER: 2.2.10.04.03 
FEP NAME: Host rock fracture aperture changes 
ORIGINATOR FEP DESCRIPTION: None. 
PRIMARY YMP FEP NUMBER: 2.2.10.05.00 
FEP NAME: Thermo-mechanical alteration of rocks above and below the repository 
ORIGINATOR FEP DESCRIPTION: Identified as "Alteration of the PTn unit by thermo-mechanical 
stress" by originator. Thermo-mechanical compression at the repository produces tension-fracturing in the 
PTn above the repository. (YMP). 
YMP PRIMARY FEP DESCRIPTION: Thermo-mechanical compression at the repository produces 
tension-fracturing in the PTn and other units above the repository. These fractures alter unsaturated zone 
flow between the surface and the repository. Extreme fracturing may propagate to the surface, affecting 
infiltration. Thermal fracturing in rocks below the repository affects flow and radionuclide transport to the 
saturated zone. 
SECONDARY YMP FEP NUMBER: 2.2.10.05.01 
FEP NAME: Thermal expansion of rocks below repository opens fractures in Paint Brush unwelded 
ORIGINATOR FEP DESCRIPTION: Rock movements driven by thermal expansion of underlying units open 
fractures through the Paintbrush nonwelded unit. This creates local zones of increased flux through the unsaturated 
units below. 
SECONDARY YMP FEP NUMBER: 2.2.10.05.02 
FEP NAME: Thermo-mechanical alteration of surface infiltration

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ORIGINATOR FEP DESCRIPTION: Thermal expansion of rocks adjacent to the repository produces tension 
fractures which reach the surface and affect location and amount of infiltration. 
PRIMARY YMP FEP NUMBER: 2.2.10.06.00 
FEP NAME: Thermo-chemical alteration (solubility, speciation, phase changes, precipitation/dissolution) 
ORIGINATOR FEP DESCRIPTION: Identified as "Far-field transport: Thermal effects on 
hydrochemistry" by originator. 
Changes in the groundwater temperature in the far-field, if significant, may change the solubility and 
speciation of certain radionuclides. This would have the effect of altering radionuclide transport processes 
operating in the far-field. 
YMP PRIMARY FEP DESCRIPTION: Thermal effects may affect radionuclide transport directly by 
causing changes radionuclide speciation and solubility in the UZ and SZ, or indirectly, by causing changes in 
host rock mineralogy that affect the flow path. Relevant processes include volume effects associated with 
silica phase changes, precipitation and dissolution of fracture-filling minerals (including silica and calcite), 
and alteration of zeolites and other minerals to clays. 
SECONDARY YMP FEP NUMBER: 2.2.10.06.01 
FEP NAME: Silica phase changes (accompanied by volume change) occur due to elevated temperature 
ORIGINATOR FEP DESCRIPTION: Certain minerals associated with the tuffs are found to undergo phase 
changes and dewater at relatively low temperature <150 C. The associated volume changes are large and for 
substantial concentrations of these minerals significant. 
SECONDARY YMP FEP NUMBER: 2.2.10.06.02 
FEP NAME: Thermochemical change 
ORIGINATOR FEP DESCRIPTION: This FEP should be interpreted as the influence on all chemical 
equilibria (and reaction kinetics, for that matter) of changes in temperature. 
SECONDARY YMP FEP NUMBER: 2.2.10.06.03 
FEP NAME: Alteration of rock properties because of 2-phase flow 
ORIGINATOR FEP DESCRIPTION: Thermally-driven 2-phase flow of water will put hot water or water 
vapor in contact with rock, producing altered phases(e.g. vitric units converted to clays and zeolites with volume 
changes) which will alter permeabilities. 
SECONDARY YMP FEP NUMBER: 2.2.10.06.04 
FEP NAME: Heat-induced chemical reactions plug small fractures; flow is preferentially redirected to large 
fractures 
ORIGINATOR FEP DESCRIPTION: Chemical reactions induced by repository heat plug smaller-aperture 
fractures. After the thermal pulse ends, percolation is diverted into larger fractures. 
SECONDARY YMP FEP NUMBER: 2.2.10.06.05 
FEP NAME: Alteration of minerals to clays (in geosphere) 
ORIGINATOR FEP DESCRIPTION: Minerals adjacent to the residual water-bearing pores are thermally 
altered to clays. 
SECONDARY YMP FEP NUMBER: 2.2.10.06.06 
FEP NAME: Calcite precipitation in hot region produces fluids depleted in calcite which dissolve calcite below 
the repository

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VIII-19 March 2000 
ORIGINATOR FEP DESCRIPTION: Water passing through the warm region around the repository is 
depleted of calcite by temperature-induced precipitation. Below the repository, the calcite-poor water dissolves out 
calcite veins in the Calico Hills nonwelded unit. 
SECONDARY YMP FEP NUMBER: 2.2.10.06.07 
FEP NAME: Precipitates from dissolved constituents of tuff and repository materials form by evaporation 
during thermal period 
ORIGINATOR FEP DESCRIPTION: Waters moving away from the hot region around the repository 
precipitate minerals derived from dissolved constituents of tuff and cements used in repository construction. These 
minerals clog pores and divert subsequent flow into fractures. 
PRIMARY YMP FEP NUMBER: 2.2.10.07.00 
FEP NAME: Thermo-chemical alteration of the Calico Hills unit 
ORIGINATOR FEP DESCRIPTION: Identified as "Alteration of the Calico Hills fractures" by 
originator. Fracture pathways in the Calico Hills are altered by the high pH fluids forming the carrier 
plume. 
YMP PRIMARY FEP DESCRIPTION: Fracture pathways in the Calico Hills are altered by the thermal 
and chemical properties of the water flowing out of the repository. 
SECONDARY YMP FEP NUMBER: None 
FEP NAME: None 
ORIGINATOR FEP DESCRIPTION: None. 
PRIMARY YMP FEP NUMBER: 2.2.10.09.00 
FEP NAME: Thermo-chemical alteration of the Topopah Spring basal vitrophyre 
ORIGINATOR FEP DESCRIPTION: Identified as "Alteration of the Topopah Spring basal vitrophyre" 
by originator. Heating the Topopah Spring basal vitrophyre with water available causes alteration of the 
glasses to clays and zeolites, with a volume increase. 
YMP PRIMARY FEP DESCRIPTION: Heating the Topopah Spring basal vitrophyre with water available 
causes alteration of the glasses to clays and zeolites. Possible effects include volume increases that plug 
fractures, changes in flow paths, creation of perched water zones, and an increase in the sorptive properties 
of the unit. 
SECONDARY YMP FEP NUMBER: 2.2.10.09.01 
FEP NAME: Formation of perched water on the altered Topopah Spring basal vitrophyre 
ORIGINATOR FEP DESCRIPTION: The topography of the altered TPS basal vitrophyre allows local low 
areas to form, in which drainage can accumulate as perched water (possibly contaminated). 
SECONDARY YMP FEP NUMBER: 2.2.10.09.02 
FEP NAME: Sorption of contaminants by the altered Topopah Spring basal vitrophyre 
ORIGINATOR FEP DESCRIPTION: Heating the Topopah Spring basal vitrophyre with water available 
causes alteration of the glasses to clays and zeolites. Such alterations affect and probably enhance the sorption 
properties of this unit. 
SECONDARY YMP FEP NUMBER: 2.2.10.09.03 
FEP NAME: Redirection of transport paths by the altered Topopah Spring basal vitrophyre

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 VIII-20 March 2000 
ORIGINATOR FEP DESCRIPTION: Heating the Topopah Spring basal vitrophyre with water available 
causes alteration of the glasses to clays and zeolites. Such alterations probably alter the direction of flow, plugging 
some fracture pathways, causing accumulation of perched water and then redirecting the flow. 
SECONDARY YMP FEP NUMBER: 2.2.10.09.04 
FEP NAME: Sorption of actinides on altered Topopah Spring basal vitrophyre 
ORIGINATOR FEP DESCRIPTION: Actinides are sorbed on the clays and zeolites which are the alteration 
products of the vitric components of the Topopah Spring basal vitrophyre. 
SECONDARY YMP FEP NUMBER: 2.2.10.09.05 
FEP NAME: Alteration of the Topopah Spring basal vitrophyre 
ORIGINATOR FEP DESCRIPTION: Alteration of the Topopah Spring basal vitrophyre causes a volumetric 
expansion.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 IX-1 March 2000 
ATTACHMENT IX 
LOCATION OF PTN ELEMENTS ALONG FOUR TRANSECTS

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 IX-2 March 2000 
To address the issue of episodic 
transient percolation, the location 
of the PTn elements are plotted 
along four east-west transects 
(N232,000, N233,000, N234,000, 
and N235,000), which are shown 
in the plot to the right. Each 
transect has a tolerance of  200 m 
in the northing direction. 
Each transect plot on the following 
page shows the location of the PTn 
element (symbols) along with the 
approximate location of the 
repository shown in red (outline 
obtained from DTN: 
SN9907T0872799.001). The 
coordinates of the elements 
originate from the LBNL mesh file 
(mpa_pch1.v1) that was 
transmitted with an Input 
Transmittal (ITN: SNL-LBL- 
99249.Tb; DTN: 
LB990701233129.001). 
Note that although the PTn thins to 
the south, PTn material still exists 
everywhere above the repository. 
The existence of the PTn above the 
repository elements should dampen 
the effects of episodic transient 
percolation. 
The souce code and output data 
from this calculation can be found 
the the Technical Data 
Management System under DTN: 
under DTN: MO9912 
SPAPTN01.006. 
230000 
232000 
234000 
236000 
238000 
168000 170000 172000 174000 
Srgrid_repository.qpc 
Northing (m) 
Easting (m)

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 IX-3 March 2000 
East-west crosssectional 
plots showing 
occurence of the PTn 
hydrogeologic unit 
1 0 00 
1 1 00 
1 2 00 
1 3 00 
1 4 00 
1 6 80 0 0 1 7 00 0 0 1 7 20 0 0 1 7 40 0 0 
P tn_ n2 3 2 .qpc 
E levation (m) 
E as ting (m) 
1 0 00 
1 1 00 
1 2 00 
1 3 00 
1 4 00 
1 6 80 0 0 1 7 00 0 0 1 7 20 0 0 1 7 40 0 0 
P tn_ n2 3 3 .qpc 
E levation (m) 
E as ting (m) 
1 0 00 
1 1 00 
1 2 00 
1 3 00 
1 4 00 
1 6 80 0 0 1 7 00 0 0 1 7 20 0 0 1 7 40 0 0 
P tn_ n2 3 4 .qpc 
E levation (m) 
E as ting (m) 
1 0 00 
1 1 00 
1 2 00 
1 3 00 
1 4 00 
1 6 80 0 0 1 7 00 0 0 1 7 20 0 0 1 7 40 0 0 
P tn_ n2 3 5 .qpc 
E levation (m) 
E as ting (m) 
N235,000 m 
N234,000 m 
N233,000 m 
N232,000 m

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 IX-4 March 2000 
Source File: ptn_v1.f V1 
c program ptn_v1.f V1 
c_______________________________________________________________________ 
c
c This program extracts four east-west transects from the LBNL site 
c model grid that contain PTn matrix elements that were grepped from 
c the original mesh file (grep 'ptnM' mpa_pch1.v1 > ptn_elem.dat). 
c The elements, materials, volumes, and coordinates are then printed 
c to four separate output files corresponding the each transect. 
c
c C.K.Ho 
c 11/23/99 
c_______________________________________________________________________ 
c23456789012345678901234567890123456789012345678901234567890123456789012 
character*5 elem, mat 
open(1,file='ptn_elem.dat',status='old') 
open(2,file='ptn_N232.dat',status='unknown') 
open(3,file='ptn_N233.dat',status='unknown') 
open(4,file='ptn_N234.dat',status='unknown') 
open(5,file='ptn_N235.dat',status='unknown') 
c...Data 
ntol=200 
n232max=232000+ntol 
n232min=232000-ntol 
n233max=233000+ntol 
n233min=233000-ntol 
n234max=234000+ntol 
n234min=234000-ntol 
n235max=235000+ntol 
n235min=235000-ntol 
c...Write headers to output files 
write(2,50) 
50 format('***Output file from ptn_v1.f: ptn_N232.dat***'/ 
& 'PTn elements from mpa_pch1.v1 that fall within ' 
& 'the band N232,000 m plus/minus 200 m'/ 
& 'Element, material, volume(m^3), x(m), y(m), z(m)') 
write(3,60) 
60 format('***Output file from ptn_v1.f: ptn_N233.dat***'/ 
& 'PTn elements from mpa_pch1.v1 that fall within ' 
& 'the band N233,000 m plus/minus 200 m'/ 
& 'Element, material, volume(m^3), x(m), y(m), z(m)') 
write(4,70) 
70 format('***Output file from ptn_v1.f: ptn_N234.dat***'/ 
& 'PTn elements from mpa_pch1.v1 that fall within ' 
& 'the band N234,000 m plus/minus 200 m'/ 
& 'Element, material, volume(m^3), x(m), y(m), z(m)') 
write(5,80) 
80 format('***Output file from ptn_v1.f: ptn_N235.dat***'/ 
& 'PTn elements from mpa_pch1.v1 that fall within ' 
& 'the band N235,000 m plus/minus 200 m'/ 
& 'Element, material, volume(m^3), x(m), y(m), z(m)') 
c...Read information from ptn_elem.dat 
7 read(1,10,end=99) elem,mat,vol,x,y,z 
10 format(a5,10x,a5,e10.4,20x,3f10.4) 
c...Check to see if element lies within one of the transects. 
c...If so, print the information to the respective output file. 
if(y.lt.n232max.and.y.gt.n232min) then 
write(2,20) elem,mat,vol,x,y,z 
20 format(2(a5,', '),e10.4,', ',2(f10.3,', '),f10.4) 
elseif(y.lt.n233max.and.y.gt.n233min) then 
write(3,20) elem,mat,vol,x,y,z 
elseif(y.lt.n234max.and.y.gt.n234min) then 
write(4,20) elem,mat,vol,x,y,z

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 IX-5 March 2000 
elseif(y.lt.n235max.and.y.gt.n235min) then 
write(5,20) elem,mat,vol,x,y,z 
end if 
go to 7 
99 stop 
end 
There are four output data files that present the coordinates of the PTn for a given east-west 
transect identified by northing coordinate. Each transect includes occurrences of the PTn " 200 
meters from the given northing coordinate. The output is written in the following manner: 
The four northing coordinates (in meters) used for the transects are: 
232,000 
233,000 
234,000 
235,000 
Grid identifier, hydrogeologic unit identifier, grid volume (in m3), and grid coordinates northing, 
easting, and elevation above sea level, respectively, all in meters. The output confirms that the 
nodes selected are from the PTn within the " 200m interval of the selected cross sections. 
Sample output data from: Ptn_n232.dat 
***Output file from ptn_v1.f: ptn_N232.dat*** 
PTn elements from mpa_pch1.v1 that fall within the band N232,000 m plus/minus 200 m 
Element, material, volume(m^3), x(m), y(m), z(m) 
Mca47, ptnM1, 0.1259E+06, 172848.000, 232093.734, 1091.8849 
Mda47, ptnM4, 0.4190E+06, 172848.000, 232093.734, 1087.6178 
Mea47, ptnM5, 0.1143E+06, 172848.000, 232093.734, 1083.4457 
Mfa47, ptnM6, 0.6340E+06, 172848.000, 232093.734, 1077.6309 
Mca98, ptnM1, 0.1152E+06, 172634.969, 232149.438, 1151.3610 
Mda98, ptnM3, 0.1107E+06, 172634.969, 232149.438, 1149.4645 
Mea98, ptnM4, 0.3410E+06, 172634.969, 232149.438, 1145.6630 
Mfa98, ptnM6, 0.6949E+06, 172634.969, 232149.438, 1136.9746 
Sample output data from: Ptn_n233.dat 
***Output file from ptn_v1.f: ptn_N233.dat*** 
PTn elements from mpa_pch1.v1 that fall within the band N233,000 m plus/minus 200 m 
Element, material, volume(m^3), x(m), y(m), z(m) 
Mda27, ptnM1, 0.1541E+06, 173034.625, 233184.234, 1024.7982 
Mea27, ptnM4, 0.3840E+06, 173034.625, 233184.234, 1020.7847 
Mfa27, ptnM5, 0.9222E+06, 173034.625, 233184.234, 1011.0783 
Mga27, ptnM6, 0.5782E+06, 173034.625, 233184.234, 999.9597 
Mda43, ptnM1, 0.1543E+06, 172273.734, 233195.266, 1171.1655 
Mea43, ptnM2, 0.1500E+06, 172273.734, 233195.266, 1168.7477 
Mfa43, ptnM4, 0.4731E+06, 172273.734, 233195.266, 1163.7947 
Mga43, ptnM5, 0.3265E+06, 172273.734, 233195.266, 1157.4543

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 IX-6 March 2000 
Sample output data from: Ptn_n234.dat 
***Output file from ptn_v1.f: ptn_N234.dat*** 
PTn elements from mpa_pch1.v1 that fall within the band N234,000 m plus/minus 200 m 
Element, material, volume(m^3), x(m), y(m), z(m) 
Mca18, ptnM1, 0.3144E+06, 172726.297, 234098.813, 1156.3379 
Mda18, ptnM2, 0.2252E+06, 172726.297, 234098.813, 1152.1523 
Mea18, ptnM3, 0.1184E+06, 172726.297, 234098.813, 1149.4949 
Mfa18, ptnM4, 0.5777E+06, 172726.297, 234098.813, 1144.1017 
Mga18, ptnM5, 0.2157E+07, 172726.297, 234098.813, 1122.9805 
Mha18, ptnM6, 0.6561E+06, 172726.297, 234098.813, 1101.2928 
Mda61, ptnM1, 0.2564E+06, 172990.063, 233838.844, 1109.7997 
Mea61, ptnM2, 0.1549E+06, 172990.063, 233838.844, 1106.5591 
Sample output data from: Ptn_n235.dat 
***Output file from ptn_v1.f: ptn_N235.dat*** 
PTn elements from mpa_pch1.v1 that fall within the band N235,000 m plus/minus 200 m 
Element, material, volume(m^3), x(m), y(m), z(m) 
Mca 8, ptnM1, 0.2360E+06, 171957.781, 235171.875, 1263.6887 
Mda 8, ptnM2, 0.7768E+06, 171957.781, 235171.875, 1256.6512 
Mea 8, ptnM3, 0.5318E+06, 171957.781, 235171.875, 1247.5916 
Mfa 8, ptnM4, 0.2115E+07, 171957.781, 235171.875, 1229.2262 
Mga 8, ptnM5, 0.3462E+07, 171957.781, 235171.875, 1190.5944 
Mha 8, ptnM6, 0.8896E+06, 171957.781, 235171.875, 1160.5358 
Mca23, ptnM1, 0.1756E+06, 172807.984, 234967.563, 1176.2024 
Mda23, ptnM2, 0.3997E+06, 172807.984, 234967.563, 1170.8516

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 X-1 March 2000 
ATTACHMENT X 
FRACTURE WATER VOLUME IN THE PERCHED WATER ZONE; 
PERCOLATION FLUX AT THE REPOSITORY HORIZON

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 X-2 March 2000 
Software routine perch_ele.fV1 
This routine is for identifying perched-water elements within and below the repository footprint 
and calculating the volume of water in these elements. Input and output files are explained in the 
comment section of the program. The code and its output files can be found in the technical 
database under the data tracking number MO9912SPAPWI01.006. The input files are in 
LB990801233129.001 through LB990801233129.012. 
(1) Code Listing: 
c
c To identify elements in perched-water zones, then identify 
c those perched-water elements within and below 
c the repository area, and then calculate the volume of 
c water in these repository footprint perched-water elements. 
c
c input files: 
c --- INCON or SAVE file. 
c --- MESH or its ELEME. 
c --- file that gives list of repository elements. 
c --- ROCKS or the TOUGH2 input file which includes ROCKS. 
c
c output files: 
c perch_ele.out --- 
c list of all saturated elements and their water pressure, 
c saturation, material name, bulk volume, and coordinates. 
c perch_ele.rep1 --- 
c list of repository footprint saturated elements, their 
c bulk volume, material name, m & f porosity, and coordinates. 
c perch_ele.rep2 --- 
c list of repository footprint perched elements, 
c and total fracure & matrix water volumes for perched elements 
c identified using the criteria below. 
c
c criterion for perched elements: 
c --- for fractures: water pressure greater than the 
c reference gas pressure: xref. 
c --- for matrix: Pw.gt.xref, and the corresponding fracture 
c element is a perched element. 
c
c note: 
c --- file_inp, file_grid, and file_rocks should be consistent. 
c --- 'vf_tot' contains total water volume in perched-water fracture 
c nodes if the fracture volumes in ELEME are pure fracture space, 
c and in such case 'wf_tot' is meaningless; this is the current 
c setup for the LBNL SR TOUGH2 output. 
c However, if the fracture volumes in ELEME 
c are bulk volumes, then 'vf_tot' contains the 
c total bulk volume, and 'wf_tot' contains total water volume 
c in perched-water fracture nodes. 
c 
double precision VOLX 
parameter (xref=0.92e05,z_cut=650.0,z_rep=1100.0) 
character*20 file_inp,file_grid,file_rep,file_rocks

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 X-3 March 2000 
character*20 file_out1,file_out2,file_out3 
character elex*5,elen*5,mele*5,eler*5,xele*5,elef*5 
c***** input files: 
c write(*,*) 'INCON or SAVE file: file_inp' 
c read(*,'(a20)') file_inp 
file_inp='SAVE.pa_glaL2.dat' 
open(13,file=file_inp,status='old') 
c write(*,*) 'MESH or its ELEME: file_grid' 
c read(*,'(a20)') file_grid 
file_grid='mpa_pch2.v1_ele' 
open(15,file=file_grid,status='old') 
c write(*,*) 'repository elements: file_rep' 
c read(*,'(a20)') file_rep 
file_rep='SR-repo-nodes' 
open(16,file=file_rep,status='old') 
c write(*,*) 'ROCKS: file_rocks' 
c read(*,'(a20)') file_rocks 
file_rocks='pa_glaL2.dat' 
open(17,file=file_rocks,status='old') 
c***** output files: 
c write(*,*) 'Output file: file_out1' 
c read(*,'(a20)') file_out1 
file_out1='perch_ele.out' 
open(21,file=file_out1) 
c write(*,*) 'Output file: file_out2' 
c read(*,'(a20)') file_out2 
file_out2='perch_ele.rep1' 
open(22,file=file_out2) 
c write(*,*) 'Output file: file_out3' 
c read(*,'(a20)') file_out3 
file_out3='perch_ele.rep2' 
open(23,file=file_out3) 
open(33,file='tmp.out') 
zmin=20000.0 
vf_tot=0. 
vm_tot=0. 
wf_tot=0. 
wm_tot=0. 
read(13,*) 
500 read(13,'(a5)') elex 
if(elex(1:3).eq.'+++') then 
rewind(22) 
510 read(22,260,end=570) xele,elen,VOLX,POR,PORF,X,Y,Z 
if(elen(1:1).eq.'F') then 
write(23,'(a5)') elen 
vf_tot=vf_tot+VOLX 
wf_tot=wf_tot+VOLX*PORF

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 X-4 March 2000 
else 
rewind(33) 
520 read(33,260,end=510) xele,elef 
if(elen(2:5).eq.elef(2:5).and.elef(1:1).eq.'F') then 
write(23,'(a5)') elen 
vm_tot=vm_tot+VOLX 
wm_tot=wm_tot+VOLX*POR 
goto 510 
endif 
goto 520 
endif 
goto 510 
570 write(23,*) 'zmin,z_cut,z_rep= ', zmin, z_cut, z_rep 
write(23,*) 'vf_tot,vm_tot= ',vf_tot,vm_tot 
write(23,*) 'wf_tot,wm_tot= ',wf_tot,wm_tot 
write(23,*) 'input files:' 
write(23,'(4a20)') file_inp,file_grid,file_rocks,file_rep 
stop 
endif 
if(elex(1:2).eq.'TP'.or.elex(1:2).eq.'BT') then 
read(13,*) 
goto 500 
endif 
read(13,600) sat_pre,d1,d2,sat_phase 
600 FORMAT(4E20.13) 
if(sat_pre.gt.xref) then 
rewind(15) 
650 read(15,150,end=800) elen,NSEQ,NADD,mele,VOLX,AHTX,X,Y,Z 
150 FORMAT(A5,2I5,A5,2E10.4,10X,3f10.3) 
if(elen.eq.elex) goto 700 
goto 650 
700 if(Z.gt.z_cut) then 
if(Z.lt.zmin) zmin=Z 
write(21,200) elex,sat_pre,sat_phase,mele,VOLX,X,Y,Z 
200 format(a5,f12.3,1x,f6.4,1x,a5,1x,e15.5,3(1x,f10.3)) 
endif 
rewind(16) 
read(16,*) 
710 read(16,'(a5)',end=500) eler 
if(elen(3:5).eq.eler(3:5)) then 
rewind(17) 
read(17,*) 
read(17,*) 
750 read(17,'(a5)') xele 
IF(xele.EQ.'REFCO'.or.xele.eq.'topbd' 
+ .or.xele.eq.'botbd') goto 500 
backspace(17) 
READ(17,210) xele,dx,POR 
210 format(a5,5x,2e10.4) 
READ(17,220) PORF 
220 format(70x,e10.4) 
READ(17,*) 
READ(17,*) 
if(xele.eq.mele) then

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 X-5 March 2000 
write(22,260) xele,elen,VOLX,POR,PORF,X,Y,Z 
260 format(2(a5,1x),e11.4,f8.4,e11.4,3f11.3) 
write(33,260) xele,elen,VOLX,POR,PORF,X,Y,Z 
goto 500 
endif 
goto 750 
endif 
goto 710 
endif 
goto 500 
800 write(*,*) 'error: no matching element in file_grid!' 
stop 
end 
(2) Example Input Files: 
(a) SAVE.pa_pchL1.dat 
A TOUGH2 SAVE file for the present-day climate, low infiltration, and perched-water model 
one. 
(b) mpa_pch1.v1_ele 
A TOUGH2 ELEME section taken from the mesh file mpa_pch1.v1, for perched-water model 
one. 
(c) SR-repo-nodes 
A file that gives list of repository elements. 
(d) pa_pchL1.dat 
A TOUGH2 input file that includes the ROCKS input section, for present-day climate, low 
infiltration, and perched-water one. 
(3) Example Output File: 
pa_pchL1.rep2 
List of repository footprint perched elements, and total fracure & matrix water volumes for 
perched elements within and below the repository footprint, for present-day climate, low 
infiltration, and perched-water model one. 
(4) Verification: 
This program has been verified by hand check and visual inspection. As an example, FCi81 in 
the output file pa_pchL1.rep2 is picked up, because the column identifier i81 exists in the 
input file SR-repo-nodes and the associated hydrologic data (gas pressure = 0.114855e06 Pa, 
and water saturation = 1.0) in the input file SAVE.pa_pchL1.dat indicates this element is under 
perched-water condition. Its contribution to the total repository-footprint perched-water volume

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 X-6 March 2000 
in the fractures is the volume (54.79 m3) taken from the input file mpa_pch1.v1_ele. Its 
corresponding matrix element, MCi81, is picked up, because, in addition to reasons similar to 
the above, FCi81 has been identified as belonging to perched-water zone. The contribution of 
MCi81 to the total repository-footprint perched-water volume in the matrix is calculated as the 
product of its element volume (0.3222e06 m3) taken from the input file mpa_pch1.v1_ele and 
its porosity (0.288) taken from the input file pa_pchL1.dat. 
(5) Output  Table X.1 
No. Case No. of 
Nodes 
Wf (m3) V (m3) Wm (m3) 
1 pa_pchL1.d 
at 
121 71459 1.249e07 2.123e06 
2 pa_pchm1. 
dat 
654 474417 7.220e07 1.091e07 
3 pa_pchu1.d 
at 
727 481183 7.983e07 1.332e07 
4 pa_pchL2.d 
at 
268 11306 3.035e07 9.105e06 
5 pa_pchm2. 
dat 
1019 44675 1.240e08 3.733e07 
6 pa_pchu2.d 
at 
2329 113664 2.958e08 9.165e07 
7 pa_glaL1.d 
at 
672 471517 7.221e07 1.108e07 
8 pa_glam1.d 
at 
775 508429 8.502e07 1.427e07 
9 pa_glau1.d 
at 
838 513904 9.134e07 1.624e07 
10 pa_glaL2.d 
at 
846 3800 1.009e08 3.016e07 
11 pa_glam2.d 
at 
1475 71464 1.712e08 5.331e07 
12 pa_glau2.d 
at 
2493 132378 3.088e08 9.543e07 
Wf = total water volume in the fractures of perched-water grid-blocks. 
V = total bulk volume of perched-water grid-blocks. 
Wm = total water volume in the matrix of perched-water grid-blocks. 
Criteria for perched-water condition: 
$ For fracture nodes, water pressure is greater than the reference gas pressure. 
$ For matrix nodes, water pressure is greater than the reference gas pressure, and 
the corresponding fracture nodes are in perched-water zone.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 X-7 March 2000 
Software routine: pflux_rep.fV1 
This routine is for calculating the repository-area percolation flux and its histogram (the latter 
function is not used in the present analysis). Input and output files are explained in the comment 
section of the program. The code and its output files can be found in the technical database 
under the data tracking number MO9912SPAPWI01.006. The input files are in 
LB990801233129.001 through LB990801233129.012. 
(1) Code Listing: 
C
C To produce percolation and percolcation histogram 
C for the repository area. 
C
C Assumption: 
C Vertical connections in the grid are from below to above, 
C i.e., the 1st node is below the 2nd node in a typical vertical 
C connection pair. 
C
C Input Files: 
C SR-repo-nodes --- list of repository nodes. 
C mpa_pch1.v1_conne or mpa_pch2.v1_conne --- connection data. 
C pa_pchL1.out or similar --- TOUGH2 output file. 
C
C Output File: 
C pflux.out --- repository percolations (kg/s, mm/yr). 
C 
parameter (ncmax=396770) 
parameter (err_sum_area_frac=0.9999,eps=0.001) 
parameter (rmin_mm=0,rmax_mm=2.0,delt_mm=2.0) 
character*20 file_inp,file_rep,file_conne,file_out 
character block*60, ele1*5, ele2*5, elex*5, elc1*5, elc2*5 
c write(6,*) 'Enter the file name for the TOUGH2 output:' 
c read(5,'(a)') file_inp 
file_inp='pa_pchu1.out' 
open (11,file=file_inp,status='old') 
c write(6,*) 'Enter the file name for repostory nodes:' 
c read(5,'(a)') file_rep 
file_rep='SR-repo-nodes' 
open (12,file=file_rep,status='old') 
c write(6,*) 'Enter the file name for the connections:' 
c read(5,'(a)') file_conne 
file_conne='mpa_pch1.v1_conne' 
open (13,file=file_conne,status='old') 
c write(6,*) 'Enter the output file name for this run:' 
c read(5,'(a)') file_out 
file_out='pflux_rep.out' 
open(21,file=file_out)

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 X-8 March 2000 
write(21,*) 'file_inp: ', file_inp 
open(31,file='pflux_rep.tmpf') 
open(32,file='pflux_rep.tmpm') 
open(33,file='pflux_rep.tmpt') 
open(41,file='pflux_rep.ref') 
flux_repf=0. 
flux_repm=0. 
area_rep=0. 
write(41,*) 'conne_pair-flux,rep_ele,conne_pair-area:' 
1000 read(11,'(a)') block 
if(block(7:18).ne.'ELEM1 ELEM2') goto 1000 
read(11,*) 
read(11,*) 
num_sumf=0 
num_summ=0 
n1=1 
n2=min(ncmax,53) 
do 1500 i=n1,n2 
read(11,1100) ele1, ele2, flo_liq 
1100 format(5x,a5,4x,a5,12x,e13.5) 
if(ele1(1:1).eq.ele2(1:1).and.ele1(3:5).eq.ele2(3:5)) then 
rewind(12) 
read(12,*) 
1300 read(12,'(a5)') elex 
if(elex.eq.'+++++') goto 1500 
if(elex(2:5).eq.ele2(2:5)) then 
if(ele2(1:1).eq.'F') flux_repf=flux_repf+flo_liq 
if(ele2(1:1).eq.'M') flux_repm=flux_repm+flo_liq 
rewind(13) 
read(13,*) 
1250 read(13,'(2a5,40x,e10.4)',end=1500) elc1,elc2,area 
if(elc1(3:5).eq.elc2(3:5).and.elc2(2:5).eq.elex(2:5)) then 
write(41,1400) ele1,ele2,flo_liq,elex,elc1,elc2,area 
1400 format(2a5,e15.5,1x,a5,1x,2a5,e15.5) 
flo=flo_liq*3.1516e07/area 
if(ele2(1:1).eq.'F') then 
num_sumf=num_sumf+1 
write(31,1450) num_sumf,ele2,flo,area 
1450 format(i5,1x,a5,2e15.5) 
area_rep=area_rep+area 
endif 
if(ele2(1:1).eq.'M') then 
num_summ=num_summ+1 
write(32,1450) num_summ,ele2,flo,area 
endif 
goto 1500 
endif 
goto 1250 
endif 
goto 1300 
endif 
1500 continue 
5000 continue

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 X-9 March 2000 
if(n2.eq.ncmax) goto 6000 
n1=n2+1 
n2=min(ncmax,N1+56) 
read(11,*) 
read(11,*) 
read(11,*) 
do 4500 i=n1,n2 
read(11,1100) ele1, ele2, flo_liq 
4100 format(5x,a5,4x,a5,12x,e13.5) 
if(ele1(1:1).eq.ele2(1:1).and.ele1(3:5).eq.ele2(3:5)) then 
rewind(12) 
read(12,*) 
4300 read(12,'(a5)') elex 
if(elex.eq.'+++++') goto 4500 
if(elex(2:5).eq.ele2(2:5)) then 
if(ele2(1:1).eq.'F') flux_repf=flux_repf+flo_liq 
if(ele2(1:1).eq.'M') flux_repm=flux_repm+flo_liq 
rewind(13) 
read(13,*) 
4250 read(13,'(2a5,40x,e10.4)',end=4500) elc1,elc2,area 
if(elc1(3:5).eq.elc2(3:5).and.elc2(2:5).eq.elex(2:5)) then 
write(41,1400) ele1,ele2,flo_liq,elex,elc1,elc2,area 
flo=flo_liq*3.1516e07/area 
if(ele2(1:1).eq.'F') then 
num_sumf=num_sumf+1 
write(31,1450) num_sumf,ele2,flo,area 
area_rep=area_rep+area 
endif 
if(ele2(1:1).eq.'M') then 
num_summ=num_summ+1 
write(32,1450) num_summ,ele2,flo,area 
endif 
goto 4500 
endif 
goto 4250 
endif 
goto 4300 
endif 
4500 continue 
goto 5000 
6000 write(21,*) 'lump fluxes & area for the repository area:' 
write(21,*) 'flux_repf (kg/s),flux_repm (kg/s),area_rep (m*m) =' 
write(21,'(3e15.4)') flux_repf, flux_repm, area_rep 
flux_repf_avg=flux_repf*3.1516e07/area_rep 
flux_repm_avg=flux_repm*3.1516e07/area_rep 
write(21,*) 'flux_repf_avg (mm/yr),flux_repm_avg (mm/yr) =' 
write(21,'(3e15.4)') flux_repf_avg, flux_repm_avg 
write(21,*) 'histogram for f+m fluxes in the repository area:' 
write(21,*) 'No & x0-x1 (mm/yr) & nsamp & freqency & cumulative =' 
rewind(31) 
do 6500 i=1,num_sumf 
read(31,1450) numf,ele1,flof,areaf 
rewind(32) 
do j=1,num_summ 
read(32,1450) numm,ele2,flom,aream 
if(ele2(2:5).eq.ele1(2:5)) then

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 X-10 March 2000 
flot=flof+flom 
write(33,1490) numf,ele1,ele2,flot,areaf 
1490 format(i5,1x,a5,1x,a5,2e15.5) 
goto 6500 
endif 
enddo 
6500 continue 
sum_area_frac=0. 
m=0 
7000 m=m+1 
dmm1=rmin_mm+(m-1)*delt_mm 
dmm2=rmax_mm+(m-1)*delt_mm 
area_frac=0. 
rewind(33) 
nsamp=0 
do i=1,num_sumf 
read(33,1490) num,ele1,ele2,flo,area 
if(flo.gt.dmm1.and.flo.le.dmm2) then 
nsamp=nsamp+1 
area_frac=area_frac+area/area_rep 
endif 
enddo 
sum_area_frac=sum_area_frac+area_frac 
write(21,2200) m,dmm1,dmm2,nsamp,area_frac,sum_area_frac 
2200 format(i5,2e12.4,i5,2e12.4) 
if(m.gt.200) then 
write(6,*) 'bin interval is too small -> too many bars.' 
stop 
endif 
if(abs(sum_area_frac-err_sum_area_frac).gt.eps) goto 7000 
stop 
end 
(2) Example Input Files: 
(a) SR-repo-nodes 
List of repository nodes. 
(b) mpa_pch1.v1_conne 
Connection data taken from the mesh file mpa_pch1.v1. 
(c) pa_pchL1.out 
TOUGH2 output file, for present-day climate, low infiltration, and perched-water model one. 
(3) Example Output File: 
pa_pchL1.pfx 
Repository-area percolation flux and its histogram, for present-day climate, low infiltration, and 
perched-water model one.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 X-11 March 2000 
(4) Verification: 
This program has been verified by hand check and visual inspection. As an example, the 
connection Frh11Fqh11, its flux 0.10617e-03 (kg/s) and its interface area 0.18610e05 (m2) 
are picked up from the input files mpa_pch1.v1_conne and pa_pchL1.out, because the layer 
identifier q in combination with the column identifier h11 appear in the input file SR-reponodes. 
For similar reasons, the connection Mrh11Mqh11 and its associated data are also 
picked up. 
(5) Output  Table X.2 
Case Qf (kg/s) 
(fracture flow 
rate) 
qf (mm/yr) 
(fracture flux) 
Qm (kg/s) 
(matrix flow 
rate) 
qm (mm/yr) 
(matrix flux) 
pa_pchL1.out 0.032 0.206 0.009 0.057 
pa_pchm1.out 0.625 4.018 0.080 0.516 
pa_pchu1.out 1.800 11.570 0.041 0.260 
pa_glaL1.out 0.248 1.593 0.023 0.148 
pa_glam1.out 3.030 19.480 0.146 0.936 
pa_glau1.out 5.980 38.450 0.075 0.484 
Note: 
1. Total percolation flux from the repository is dependent on the climate and infiltration 
scenario only. It has nothing to do with perched-water model, which differs only below the 
repository. Therefore, only perched-water model 1 is used in this calculation. 
2. Qf and qf refer to the total fracture percolation flux and average fracture percolation rate 
from the repository, respectively. Qm and qm refer to the total matrix percolation flux and 
average matrix percolation rate from the repository, respectively. 
3. Total area of the repository: 0.4902e07 m2. 
The amount of water released relative to the natural flux through the potential repository can be 
evaluated by taking the ratio of the volume of water in the fractures of the perched water zone 
(from Table X.1) and dividing by the total flux rate (volume flow rate for fractures and matrix 
from Table X.2) through the potential repository. The range of times is shown to range from less 
than 1 year to 55 years.

Features, Events, and Processes in UZ Flow and Transport 
ANL-NBS-MD-000001 REV 00 X-12 March 2000 
Table X.3 
No. Case Wf (m3) Qf +Qm 
(m3/yr) 
Time (yr) 
Wf/(Qf+Qm) 
1 pa_pchL1.d 
at 
71459 1.29e03 55 
2 pa_pchm1. 
dat 
474417 2.220e04 21 
3 pa_pchu1.d 
at 
481183 5.81e04 8 
4 pa_pchL2.d 
at 
11306 1.29e03 9 
5 pa_pchm2. 
dat 
44675 2.220e04 2 
6 pa_pchu2.d 
at 
113664 5.81e04 2 
7 pa_glaL1.d 
at 
471517 8.55e03 55 
8 pa_glam1.d 
at 
508429 1.00e05 5 
9 pa_glau1.d 
at 
513904 1.91e05 3 
10 pa_glaL2.d 
at 
3800 8.55e03 0.4 
11 pa_glam2.d 
at 
71464 1.00e05 0.7 
12 pa_glau2.d 
at 
132378 1.91e05 0.7