APPENDIX A

QUALITY ASSURANCE REVIEW OF THE

PCS-2012 PA PARAMETER DATABASE
ii

TABLE OF CONTENTS

Abbreviations and Acronyms ........................................................................................................ iv

Executive Summary.........................................................................................................................v

1.0 Introduction..........................................................................................................................1

2.0 Approach..............................................................................................................................3

3.0 Review of Parameter Database Migration ...........................................................................5

4.0 Review of Parameters used in PCS-2012 that have Changed Since PABC-2009...............7

4.1 Errors Identified in Parameter Data Entries.............................................................7

4.2 Transparency Concerns Identified in Parameter Data Entries.................................8

4.3 Review of Supporting Documentation...................................................................10

4.3.1 Use of Default Values................................................................................27

4.3.2 ROM Salt Porosity and Permeability Values.............................................27

4.3.3 PCS DRZ Porosity and Permeability Values.............................................30

4.3.4 Two-Phase Flow Parameters......................................................................31

4.4 Review of PAPDB Database-to-Code Interface for PCS-2012.............................34

5.0 Parameter Data Entry Process Review ..............................................................................43

6.0 Computing Hardware.........................................................................................................44

7.0 Conclusions........................................................................................................................45

References......................................................................................................................................46
iii

LIST OF TABLES

Table 1. Parameters Used in the PCS-2012 PA that have Changed since PABC-2009 ............11

Table 2. Justification Check for Parameters Used in the PCS-2012 PA that have 

Changed since PABC-2009 .........................................................................................14

Table 3. Database-Code Interface Test Results for Parameters Used in the PCS-2012 PA 

that have Changed since PABC-2009..........................................................................36

Table 4. WIPP PA Alpha Cluster Nodes Used in PCS-2012.....................................................44
iv

ABBREVIATIONS AND ACRONYMS

CCA Compliance Certification Application

CFR Code of Federal Regulations

DOE or the

Department U.S. Department of Energy

DRZ Disturbed Rock Zone

EPA or the

Agency U.S. Environmental Protection Agency

ERMS Electronic Record Management System

HP Hewlett Packard

PA Performance Assessment

PABC-2009 2009 WIPP Performance Assessment Baseline Calculation

PAPDB Performance Assessment Parameter Database

PAVT Performance Assessment Verification Test

PC3R Panel Closure Redesign and Repository Reconfiguration Analysis

PCS Panel Closure System

PDE Parameter Data Entry

QA Quality Assurance

ROM Run-of-Mine

SAN Storage Area Network

SNL Sandia National Laboratories

T1 First Time Period (0 to 100 years)

T2 Second Time Period (100 to 200 years)

T3 Third Time Period (200 to 10,000 years)

TBM Technical Baseline Migration

TSD Technical Support Document

VBA Virtual Basic for Applications

WIPP Waste Isolation Pilot Plant
v

EXECUTIVE SUMMARY

This appendix documents a quality assurance review of the changes made by DOE/SNL to the 

WIPP Performance Assessment Database (PAPDB) for the PCS-2012 PA. Of the approximately 

1,700 parameters in the PAPDB, 78 changes were made since PABC-2009. Most of the changes 

involved the assignment of existing parameter names and values to newly defined materials for 

the three time periods used to model consolidation of both the ROM salt and the disturbed rock 

zone (PCS DRZ) above and below the salt. All ROM salt materials for the third time period were 

new because three different time periods had not previously been used in WIPP PA. Three data 

errors were identified by the Agency in the PCS-2012 PAPDB. These involved an erroneous 

value for the mean of a distribution, an erroneous designation of a distribution type (loguniform 

instead of uniform), and transposition of the mean and median values of a distribution. However, 

none of these errors adversely affected PCS-2012 results. EPA has brought these errors to DOE’s 

attention and has received assurances that they will be corrected.

A review of primary and secondary supporting documents was conducted for all parameter 

changes and all documents were quickly retrieved from the WIPP Records Center. Although the 

parameter values were generally correct, many of the supporting documents were not found to 

adequately justify those parameter values as used in the PCS-2012 analysis, and many had 

transparency weaknesses because the cited source documents were prepared for other analyses 

and the associated metadata described those analyses rather than the PCS-2012 PA. For example, 

the designated supporting document may have described a parameter that was used in an earlier 

analysis for a time period extending from zero to 200 years, but was used in the PCS-2012 PA 

for a time period extending from zero to 100 years. Transparency issues generally become 

problems for those trying to understand an analysis they are not already familiar with. DOE’s 

approach was to explain the differences in the supporting documentation, however EPA believes 

that the database should be consistent with the supporting documentation. The justification 

weaknesses were resolved in part by the Agency’s independent review of the technical basis for 

many of the parameter values, and in part because of the need to leave some existing parameter 

values unchanged to minimize differences between the PCS-2012 and the baseline PABC-2009, 

so that the differences in performance results could be readily attributable to the principal effects 

of changing the PCS design. However, modeling the progressive consolidation of ROM salt in a 

waste panel access drift and the subsequent consolidation of the surrounding DRZ involves 

processes and parameters that are new to WIPP PA. If the alternative PCS design proposed by 

DOE is implemented, the Agency will thoroughly evaluate all associated parameter values for 

continued relevance for use in future PAs. 

A database interface evaluation was performed for all new parameters and the correct parameter 

values were retrieved from the PAPDB with the exception of one instance where the distribution 

identified for the parameter in the PAPDB was not properly sampled. However, this error did not 

affect the PCS-2012 PA results because the returned value was the desired value. The Agency 

has brought this error to DOE’s attention and has received assurances that it will be corrected.

Procedures for developing, documenting, controlling, and changing parameters, and for entering 

those parameters into the PAPDB, were also reviewed. The Agency found all procedural changes 

to be consistent with earlier versions and found all revisions to be appropriate.
vi

In summary, many more concerns were raised by this review than were raised in previous PA 

parameter reviews. However, as documented in this report, the problems identified by the 

Agency concern details of the PCS-2012 parameters that did not affect the overall PA results.
1

1.0 INTRODUCTION

The panel closure system (PCS) at the Waste Isolation Pilot Plant (WIPP) consists of barriers 

constructed in access drifts to filled waste panels that close the panels to further access, and 

reduce brine and gas transfer between the filled panels and the rest of the repository. The U.S. 

Department of Energy (the Department or DOE) has proposed to change the PCS design from 

the current “Option D” design, consisting of a concrete monolith and an explosion wall, to a 

design nominally consisting of 100 feet of run-of-mine (ROM) crushed salt fill between two 

ventilation bulkheads. Where explosion walls already exist, only one ventilation bulkhead would 

be constructed on the outboard side of the ROM salt. The purpose of these bulkheads is to 

restrict air flows and personnel access to filled waste panels. DOE expects the ROM salt panel 

closure to be easier and less expensive to construct than the Option D design. In addition, the 

proposed design eliminates the need for an explosion wall, which has been found to be 

unnecessary because of low volatile gas concentrations in the waste panels (Nelson 2011). The 

two alternative PCS designs are more fully described in Camphouse et al. (2012a). Changing the 

panel closure design would require a new rulemaking by the U.S Environmental Protection 

Agency (the Agency or EPA), because one of the conditions in the 1998 Agency rulemaking that 

certified WIPP to receive transuranic waste mandated use of the Option D design.

The short-term purpose of the PCS is to minimize the impact of filled waste panels on the rest of 

the WIPP repository for worker protection during the repository’s operational period. After the 

operational period ends and the repository is closed, DOE expects that increasing pressure from 

the surrounding bedded salt as it creeps into the filled access drifts will consolidate the ROM salt 

and eventually return it to the near undisturbed, in situ conditions of very low permeability and 

porosity. Over the long term, DOE expects the decreasing permeability will increasingly isolate 

each waste panel by reducing the exchange of brine and gas with the rest of the repository.

Sandia National Laboratories (SNL), DOE’s science advisor, designed the PCS-2012 

performance assessment (PA) to compare the long-term performance of the WIPP repository 

with the proposed ROM salt PCS against the long-term performance with the original Option D 

PCS. This was achieved by revising the parameter values in the PABC-2009 PA, which is the 

current regulatory baseline, to reflect the proposed use of crushed salt instead of concrete, and to 

simulate the progressive consolidation of the crushed salt during creep closure. The changes 

primarily affect the BRAGFLO Salado Flow PA model. Only those changes that directly relate 

to the panel closure materials and their consolidation were made (Camphouse et al. 2012a). The 

ventilation bulkheads were not simulated in the PCS-2012 PA because SNL does not consider 

them to have long-term functionality (Camphouse et al. 2012a). The only change in the 

BRAGFLO model grid was to better simulate the ROM salt panel closure, which is about 10 m 

shorter than the Option D concrete monolith (Camphouse et al. 2012a). DOE evaluated the effect 

of the proposed ROM salt PCS on long-term repository performance by comparing the results of 

the PCS-2012 PA against those of the PABC-2009 PA.

This appendix describes the Agency’s review of the Performance Assessment Parameter 

Database (PAPDB), parameter traceability, adequacy of parameter documentation, and changes 

to the performance assessment (PA) parameters used to support DOE’s PCS-2012 PA. The 

results of this review document the Agency’s evaluation of DOE’s compliance with the
2

requirements of 40 CFR 194.23(c)(4). The PAPDB is a computerized database that contains the 

values of parameters used in PA calculations. The PAPDB also records a history of parameter 

value changes for different PA runs. It identifies metadata, such as parameter names, units, and 

distribution characteristics, and it identifies supporting documentation. Following completion of 

the PABC-2009 PA, SNL migrated the PAPDB to a new version and platform to improve its 

ease of use and to facilitate access of the parameter data by the PA codes.
3

2.0 APPROACH

This review was conducted by Agency and contractor personnel. The scope of the review 

included the following:

Verification and documentation of the PAPDB migration to a new platform

Verification and documentation of changes made to the PAPDB for the PCS-2012 PA

Reviewing procedural documentation supporting database changes

Reviewing and evaluating supporting metadata for new and changed parameter values

Checking the ability of PA codes to accurately access input parameters from the new 

database

The primary objectives of the Agency’s review were to assess the accuracy of the database 

migration to the new platform and to assess the transcription accuracy, documentation, and 

traceability of changes to the parameter values and metadata that were made for the PCS-2012 

PA. Parameter values and modeling approaches for the PCS-2012 PA were proposed by DOE in 

February 2012. Several concerns were raised by the Agency during its evaluation of DOE’s 

proposal and a final modeling approach was agreed upon in June 2012. The Agency’s review of 

the adequacy of DOE’s implementation of the modeling approach was initiated in October 2012 

with an on-site review of the PAPDB and its PA code interfaces. The PAPDB parameter 

database and associated metadata are maintained in Carlsbad, New Mexico, by SNL. Hard and 

electronic copies of documentation supporting the parameters and their values are maintained in 

SNL’s WIPP Records Center in Carlsbad. The supporting documents are tracked by SNL’s 

Electronic Record Management System (ERMS), through which a unique identifying number is 

assigned to each document. 

The parameter changes from PABC-2009 to PCS-2012 consisted of 48 new parameters for the 

ROM salt and 30 new parameters for the disturbed rock zone (DRZ) above and below the ROM 

salt. This zone is herein identified as the PCS DRZ. The following activities were conducted in 

reviewing these parameter changes and the aforementioned database migration during the 

Agency review team’s October 2012 visit to Carlsbad:

Reviewed the structure of the new PAPDB and the steps taken by SNL to confirm an 

accurate migration of the PABC-2009 parameter values and associated metadata into the 

new database.

Reviewed the accuracy of data entry into the PAPDB by visually comparing the online 

PAPDB values with the values on the Parameter Data Entry (PDE) forms for every new 

parameter. Parameter units, distribution type, statistics, names, and references were also 

reviewed.
4

Checked PDE forms of all new and changed parameters for completeness, signatures, and 

references to supporting documentation.

Reviewed supporting documentation identified on the PDE forms for every new 

parameter to confirm accuracy of parameter values on the PDE forms and to evaluate the 

traceability of the parameter changes.

Reviewed the ability of the current PA codes to accurately access every new input 

parameter from the database.

Follow-up activities were subsequently conducted by e-mail, telephone, and a return visit to 

Carlsbad in November 2012. SNL provided clarifications, copies of applicable data entry and 

handling quality assurance procedures, and copies of additional documentation as requested to 

address issues that developed as the review of the database changes proceeded. 
5

3.0 REVIEW OF PARAMETER DATABASE MIGRATION

Following completion of PABC-2009, SNL developed new database software, called PAPDB 

Version 2.00, to replace the previous PAPDB Version 1.00, and migrated the parameter values 

and associated metadata from Version 1.00 to Version 2.00. The database structure was modified 

to make it easier to use and to facilitate parameter data access from the PA codes on Solaris, 

Linux, and VMS platforms. The new database resides on a MySQL Server and is physically 

located on an Intel-based server running Solaris 11 (Kirchner and Long 2012). The database 

migration process is more fully described by Kirchner (2011).

A primary improvement in the new database is the ability to accurately retrieve parameter values 

used in earlier PAs. PAPDB Version 2.00 is designed to default to the parameter value most 

recently entered into the database, and to automatically log in the analysis that used the 

parameter value. However, if desired, an earlier value can be returned by specifying an earlier 

analysis. A similar functionality was provided in PAPDB Version 1.00, but did not work 

properly. In addition, distributed parameters are now assigned a default value for use when the 

distribution is not to be sampled. For example, when assigning three-dimensional, isotropic 

permeability values to a material, only the value of PRMX_LOG is randomly sampled using the 

PRELHS code. The constant default values for PRMY_LOG and PRMZ_LOG are taken from 

the database as placeholders and are subsequently reassigned the same value as PRMX_LOG in 

the BRAGFLO ALGEBRA file. 

The methodology for retrieving parameter values from the database remains essentially 

unchanged. The MATSET code retrieves the default value for every parameter in the analysis. 

Parameter values that are to be sampled are identified in the input files to the PRELHS code, 

which supplies that information to the LHS code. The LHS code then retrieves 100 sample 

values per replicate from the database and supplies them to the post LHS code. If a parameter has 

been retrieved by LHS, the POSTLHS code replaces the default parameter value retrieved by 

MATSET with the parameter value retrieved by LHS. In a subsequent step, the remaining default 

values retrieved by MATSET for distributed parameters are replaced by the desired value in the 

ALGEBRA1 file, as described in the example above. For constant parameters, the default value 

is the constant value and remains unchanged. Although the default values for distributed 

parameters are typically the means or medians of the distributions, any value can be used as the 

default value. 

The PAPDB Version 2.00 database tables are constructed to store the data residing in PAPDB 

Version 1.00. An Access database, ParamTransfer.mdb, was used to transfer the data from 

PAPDB Version 1.00 to PAPDB Version 2.00. Most of the transfers were done using queries to 

extract the data from the PAPDB Version 1.00 and append it to tables in PAPDB Version 2.00. 

The transfers were checked for completeness using a series of queries and, for the parameter 

value data, two VBA (Visual Basic for Applications) routines. The queries were designed to 

compare the PAPDB Version 2.00 values with the corresponding values in PAPDB Version 1.00 

and to show only records in the PAPDB Version 1.00 that were not matched in the PAPDB 

Version 2.00. Thus, the desired outcome was an empty data set. 
6

Verification of the transfer process involved a transfer of the data followed by the deletion of 

selected records from the various tables and execution of the various queries to show that the 

missing records were detected. Following the verification of the procedures, the data were 

transferred once again and the same queries run to verify that no records were dropped during the 

transfer. It was also necessary to generate a report that showed the records whose value string 

could not be matched due to differences in formatting. The records shown in that report were 

compared and verified to be equivalent.

In addition to the records transferred from PAPDB Version 1.00, two sets of records were 

developed that were missing from the original database. The design of PAPDB Version 1.00 did 

not allow for multiple analyses being run under a single Analysis Plan (AP), as was done for AP132. It appears to have kept only the records from the most recent retrieval of parameters. 

Furthermore, the retrieval of parameters by MATSET for use in NUTS seems to never have been 

recorded. To capture these usages of parameters, a series of queries were run to insert the 

missing records.

The data were transferred following verification of the transfer procedures. SNL verified an 

accurate data transfer by reviewing the comparison reports, as documented by Kirchner and 

Long (2012). Problems found in initial data transfers were corrected and in the final transfer, all 

of the comparison tests were successful except one, where the data did not exactly match due to 

formatting differences. Those test results were reviewed manually and the values of the two data 

sets were found to be equivalent.

The transfer process was reviewed by the Agency and detailed documentation of that review is 

presented in Appendix A.
7

4.0 REVIEW OF PARAMETERS USED IN PCS-2012 THAT HAVE 

CHANGED SINCE PABC-2009

This review evaluated 78 new parameters out of approximately 1,700 parameters currently in the 

PAPDB. All changes to the PABC-2009 parameter database involve new parameters, because 

the use of ROM salt panel closures is new to WIPP PA. Three time periods with varying material 

properties were introduced in PCS-2012 to represent time-dependent consolidation of the ROM 

salt panel closure material and the related time-dependent healing of the DRZ above and below 

the PCS. Time period T1 extends from repository closure (at time zero) to 100 years, time period 

T2 extends from 100 to 200 years, and time period T3 extends from 200 years to the end of the 

regulatory time frame at 10,000 years. Time-dependent changes were not needed for the 

properties of the Anhydrite AB layer modeled within the DRZ above the ROM salt, because 

anhydrite does not exhibit the creep characteristics of halite and would be little affected by the 

proposed change to ROM salt as the panel closure material.

The parameters representing the ROM salt PCS were separately entered in the PAPDB for each 

of the three time periods, as reflected in the material names. The parameters representing the 

DRZ above and below the ROM salt were assigned pre-existing material names DRZ_1 and

DRZ_PCS. These material names were originally developed by SNL for a 2006 analysis of a 

ROM salt PCS, called AP-129, which was never formally reviewed by the Agency. Material 

DRZ_1 is used in PCS-2012 to represent the properties of the PCS DRZ during time periods T1 

and T2, and material DRZ_PCS is used in PCS-2012 to represent the properties of the PCS DRZ 

during time period T3. 

The new parameters are identified in Table 1. This table presents the parameter names 

(consisting of a material name and a property name), the distribution type, the parameter values 

used in the PCS-2012 analysis, the analysis where the parameter value was first used, the 

parameter units, and the PA code(s) using the parameter. The Parameter Data Entry (PDE) form 

provides the source information for parameter values and associated metadata to be entered into 

the PAPDB.

4.1 ERRORS IDENTIFIED IN PARAMETER DATA ENTRIES

The parameter values and metadata entered into the PAPDB were visually compared with those 

on the PDE forms and the following data entry errors were identified. As noted below, none of 

these errors resulted in impacts to the PCS-2012 PA:

Parameters PCS_T1:PRMY_LOG and PCS_T1:PRMZ_LOG were identified on PDE 

form PDE 2012a and entered in the PAPDB as having loguniform distributions, whereas 

they should have been identified as having uniform distributions. Parameter 

PCS_T1:PRMX_LOG was properly identified and sampled from a uniform distribution. 

No impact to the PCS-2012 PA resulted from this error, because constant default values 

were taken from the PAPDB for PCS_T1:PRMY_LOG and PCS_T1:PRMZ_LOG, and 

later set equal to the sampled value of PCS_T1:PRMX_LOG in the BRAGFO 

ALGEBRA1 file. The correct distributions for these parameters are given in Table 1.
8

The mean of the uniform distribution for parameter PCS_T3:POROSITY was identified 

in the source document Camphouse (2012), on PDE form PDE 2012b, and in the PAPDB 

as 0.05, whereas it should have been entered as 0.0265. Again, no impact to the PCS2012 PA resulted from this error, because the mean is not used in LHS when developing 

a sampling scheme for a uniform distribution. The correct mean value for this parameter 

is given in Table 1.

The mean and median values of the cumulative distribution for PCS_T3:SAT_RBRN are 

reversed on PDE form PDE 2012b and in the PAPDB. The mean should be 0.25 and the 

median should be 0.2, consistent with the means and medians for the parallel parameters 

PCS_T1:SAT_RBRN and PCS_T2:SAT_RBRN. Again, no impact to the PCS-2012 PA 

resulted from this error, because the constant default value was taken from the PAPDB 

for PCS_T3:SAT_RBRN and later set equal to the sampled value of 

PCS_T1:SAT_RBRN in the BRAGFLO ALGEBRA1 file. The correct mean and median 

values for this parameter are given in Table 1. 

4.2 TRANSPARENCY CONCERNS IDENTIFIED IN PARAMETER DATA

ENTRIES

The Agency’s transparency review of parameter data entries focused on the clarity and 

completeness of the PDE forms. All PDE forms were found to have properly entered and dated 

signatures of the individuals responsible for Concurrence, Data Entry, and QA 

Reviewer/Checker. The traceability concerns identified by the Agency most commonly resulted 

from the use of source documents that were prepared for analyses other than the PCS-2012 PA. 

Although the parameter names and values were the same in these earlier documents and resulted 

in no errors for the PCS-2012 PA, the metadata referred to different applications of the 

parameter, which would be misleading to someone not familiar with the PCS-2012 PA. The 

Agency’s findings for each new parameter are presented in Table 2. Several of the more common 

transparency concerns are summarized below:

The parameter values to be entered into the PAPDB are commonly identified in the PDE 

forms by attaching one or more pages from source documents containing tables of 

parameter values and indicating on those tables which parameter values are relevant to 

the specific PDE form. The Agency has noted a transparency concern regarding this 

practice, as exemplified by PDE form PDE 2012a. The parameter values to be entered are 

currently indicated by arrows in the margins pointing at the row in the table containing 

the relevant parameter and value, whereas in the past, those rows containing parameters 

and values not relevant to the particular PDE were lined out and those that were relevant 

were circled. The current process can be made more transparent by explaining the 

significance of the arrows in the PDE form and lining out the non-relevant parameters, or 

by reverting to the previous practice of circling the relevant parameters and lining out the 

rest.

The sources of the parameter values to be entered into the PAPDB are sometimes 

identified on tables attached to the PDE forms that were taken from source documents. 

This practice can be misleading, because although the source of the attached table can be 

inferred to be the source document identified on the PDE form, the “sources” of the 
9

parameter values identified on the table are second tier documents only identified in the 

reference list of the document from which the table was taken, and are not given on the 

PDE form or its attachments. An example is again PDE form PDE 2012a, where the 

“source” of the parameter value is identified on the attached table as, for example, 

“Patterson Page 13” or “This memo.” A clarifying note should be added that “This 

memo” does not refer to this PDE form or its attachments, but to Camphouse (2012), and 

that the citation to “Patterson” can be found in the reference list for the primary source 

document Camphouse (2012), which is identified on the PDE form.

Two parameters, PCS_T3:PORE_DIS and PCS_T3:SAT_RBRN, are assigned 

cumulative distributions and have documented mean values in the PAPDB. However, 

PDE form PDE 2012b for these properties does not show mean values for these 

distributions and therefore could not have been the source for them. Data entry 

information for the T1 and T2 versions of these parameters (for example, PDE form PDE 

2006c for PCS_T1:PORE_DIS) was documented on an earlier version of the PDE form 

that prompts entry of mean values and does document those values. 

Those parameters on Table 1 referenced to a First Use analysis of AP-129 are 

documented in PDE forms prepared in 2006 for SNL’s Redesigned Panel Closure System 

Analysis. Because that analysis used the same material names PCS_T1 and PCS_T2, and 

the same parameter types and values as in the current PCS-2012 PA, the PAPDB entries 

for AP-129 were used without modification for PCS-2012. A transparency concern arose 

in the metadata, however, because the parameter descriptions have changed since the AP129 analysis. In the PCS-2012 analysis, time period T1 extends from zero to 100 years, 

while in the AP-129 analysis, time period T1 is described in the PDE form as extending 

from zero to 200 years. Also, in the PCS-2012 analysis, time period T2 extends from 100 

to 200 years, while in the AP-129 analysis, time period T2 is described in the PDE form 

as extending from 200 to 10,000 years. Examples are provided in PDE forms PDE 2006a

and PDE 2006b for parameters PCS_T1:COMP_RCK and PCS_T2:COMP_RCK. To 

avoid confusion, new PDE forms with new parameter descriptions should have been 

developed for the PCS-2012 analysis. SNL’s practice of explaining these differences in 

parameter descriptions in the source documents is not adequate, because the database and 

the source documents should be consistent.

The DRZ_1 parameters on Table 1 referenced to a First Use analysis of CCA and TBM

are documented in PDE forms prepared in 1996 for the CCA and in 2002 for the TBM. 

Because those analyses used the same material name DRZ_1 and the same parameter 

types and values as in the current PCS-2012 PA, the PAPDB entries for those parameters 

were used without modification for PCS-2012. A transparency concern arose in the 

metadata, because the parameter descriptions have changed since the CCA and TBM 

analyses. In the CCA and TBM, material DRZ_1 is described as “Disturbed Rock Zone: 

0 to 1000 yrs” (for example, see PDE Form SNL 1997 for DRZ-1:RELP_MOD, dating to 

the 1996 CCA database). In the PCS-2012 PA, material DRZ_1 is applied to the 

properties of the DRZ above and below the PCS during the time period from zero to 

200 years. The current definition is not the same as that originally adopted for the CCA 

and TBM. To avoid confusion, new PDE forms with new parameter descriptions should 
10

have been developed for the PCS-2012 analysis for parameter descriptions dating back to 

the CCA and TBM.

4.3 REVIEW OF SUPPORTING DOCUMENTATION

Table 2 summarizes an assessment of the adequacy of supporting documentation for justifying 

the parameter changes. Table 2 provides the parameter name (material and property names), a 

description of the parameter type, ERMS numbers for the PDE form and principal supporting 

document(s), the effective date of the change, and comments that summarize the basis for the 

change.1

As previously mentioned, several concerns were raised by the Agency during its evaluation of 

the parameter values proposed by DOE for the PCS-2012 PA, and a final agreement was reached 

in June 2012. This agreement was based upon the modeling approach and parameter values 

described in a May 2012 memo by Camphouse et al. (2012a) and upon a proposal by DOE to 

lower the minimum permeability value of the ROM salt during time period T1 from 

-18.7 log(m2), as proposed by Camphouse et al. (2012a), to -21.0 log(m2). The development of 

permeability values for the time-dependent consolidation of the crushed salt and the surrounding 

DRZ is further described below. As also described below, the Agency approved keeping several 

parameter values the same as in the baseline PABC-2009 PA to facilitate a direct comparison of 

results. However, when approving the PCS-2012 modeling approach and parameter values, the 

Agency noted that the PCS-2012 PA was designed and parameterized to facilitate a comparison 

of results, and that the appropriateness of continuing to use the same modeling approach and 

parameter values would be re-evaluated for the 2014 recertification PA.

 

1

Parameter Data Entry (PDE) forms are identified by ERMS number in this report and are not included in 

the reference list.
11

Table 1. Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material Name Property Name Distribution 

Type

Parameter Value Used in PCS-2012 PA First 

Use

Parameter 

Units Used in Code

Mean Other Minimum Maximum Default

PCS_T1 CAP_MOD Constant 1 - - 1 1 1 PC3R None BRAGFLO

PCS_T2 CAP_MOD Constant 1 - - 1 1 1 PC3R None BRAGFLO

PCS_T3 CAP_MOD Constant 1 - - 1 1 1 AP 161 None BRAGFLO

PCS_T1 COMP_RCK Constant 8.0E-11 - - 8.0E-11 8.0E-11 8.0E-11 AP 129 Pa-1 BRAGFLO

PCS_T2 COMP_RCK Constant 8.0E-11 - - 8.0E-11 8.0E-11 8.0E-11 AP 129 Pa-1 BRAGFLO

PCS_T3 COMP_RCK Constant 8.0E-11 - - 8.0E-11 8.0E-11 8.0E-11 AP 161 Pa-1 BRAGFLO

PCS_T1 KPT Constant 0.0 - - 0.0 0.0 0.0 AP 129 None BRAGFLO

PCS_T2 KPT Constant 0.0 - - 0.0 0.0 0.0 AP 129 None BRAGFLO

PCS_T3 KPT Constant 0.0 - - 0.0 0.0 0.0 AP 161 None BRAGFLO

PCS_T1 PC-MAX Constant 1E08 - - 1E08 1E08 1E08 AP 129 Pa BRAGFLO

PCS_T2 PC-MAX Constant 1E08 - - 1E08 1E08 1E08 AP 129 Pa BRAGFLO

PCS_T3 PC-MAX Constant 1E08 - - 1E08 1E08 1E08 AP 161 Pa BRAGFLO

PCS_T1 PCT_A Constant 0.0 - - 0.0 0.0 0.0 PC3R Pa BRAGFLO

PCS_T2 PCT_A Constant 0.0 - - 0.0 - - 0.0 PC3R Pa BRAGFLO

PCS_T3 PCT_A Constant 0.0 - - 0.0 - - 0.0 AP 161 Pa BRAGFLO

PCS_T1 PCT_EXP Constant 0.0 - - 0.0 - - 0.0 PC3R None BRAGFLO

PCS_T2 PCT_EXP Constant 0.0 - - 0.0 - - 0.0 PC3R None BRAGFLO

PCS_T3 PCT_EXP Constant 0.0 - - 0.0 - - 0.0 AP 161 None BRAGFLO

PCS_T1 PO_MIN Constant 1.01325

E05 - -

1.01325

E05

1.01325

E05

1.01325

E05 AP 129 Pa BRAGFLO

PCS_T2 PO_MIN Constant 1.01325

E05 - -

1.01325

E05

1.01325

E05

1.01325

E05 AP 129 Pa BRAGFLO

PCS_T3 PO_MIN Constant 1.01325

E05 - -

1.01325

E05

1.01325

E05

1.01325

E05 AP 161 Pa BRAGFLO

PCS_T1 PORE_DIS Cumulative 2.52 Median

0.94 0.11 8.1 0.94 AP 129 None PRELHSBRAGFLO

PCS_T2 PORE_DIS Cumulative 2.52 Median

0.94

0.11 8.1 0.94 AP 129 None BRAGFLO

PCS_T3 PORE_DIS Cumulative 2.52 Median

0.94 0.11 8.1 0.94 AP 161 None BRAGFLO

PCS_T1 POROSITY Uniform 0.1265 - - 0.066 0.187 0.1265 AP 161 None PRELHS

BRAGFLO

PCS_T2 POROSITY Uniform 0.05 - - 0.025 0.075 0.05 AP 161 None

PRELHS

BRAGFLO

PCS_T3 POROSITY Uniform 0.0265 - - 0.001 0.0519 0.0265 AP 161 None PRELHS

BRAGFLO

PCS_T1 PRMX_LOG Uniform -16.5 - - -21 -12 -16.5 AP 161 log(m2)

PRELHS

BRAGFLO

PCS_T1 PRMY_LOG Uniform -16.5 - - -21 -12 -16.5 AP 161 log(m2) BRAGFLO

PCS_T1 PRMZ_LOG Uniform -16.5 - - -21 -12 -16.5 AP 161 log(m2) BRAGFLO
12

Table 1. Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material Name Property Name Distribution 

Type

Parameter Value Used in PCS-2012 PA First 

Use

Parameter 

Units Used in Code

Mean Other Minimum Maximum Default

PCS_T2 POR2PERM Normal 0.0 Std Dev

0.86 -1.72 +1.72 0.0 AP 161 None PRELHSBRAGFLO

PCS_T2 PRMX_LOG Constant -18.6 - - -18.6 -18.6 -18.6 AP 161 log(m2) BRAGFLO

PCS_T2 PRMY_LOG Constant -18.6 - - -18.6 -18.6 -18.6 AP 161 log(m2) BRAGFLO

PCS_T2 PRMZ_LOG Constant -18.6 - - -18.6 -18.6 -18.6 AP 161 log(m2) BRAGFLO

PCS_T3 POR2PERM Normal 0.0 Std Dev

0.86 -1.72 +1.72 0.0 AP 161 None BRAGFLO

PCS_T3 PRMX_LOG Constant -19.1 - - -19.1 -19.1 -19.1 AP 161 log(m2) BRAGFLO

PCS_T3 PRMY_LOG Constant -19.1 - - -19.1 -19.1 -19.1 AP 161 log(m2) BRAGFLO

PCS_T3 PRMZ_LOG Constant -19.1 - - -19.1 -19.1 -19.1 AP 161 log(m2) BRAGFLO

PCS_T1 RELP_MOD Constant 4 - - 4 4 4 AP 129 None BRAGFLO

PCS_T2 RELP_MOD Constant 4 - - 4 4 4 AP 129 None BRAGFLO

PCS_T3 RELP_MOD Constant 4 - - 4 4 4 AP 129 None BRAGFLO

PCS_T1 SAT_IBRN Uniform 0.1 - - 0.04 0.16 0.1 AP 161 None PRELHS

BRAGFLO

PCS_T1 SAT_RBRN Cumulative 0.25 Median

0.2 0.0 0.6 0.2 AP 129 None PRELHSBRAGFLO

PCS_T2 SAT_RBRN Cumulative 0.25 Median

0.2 0.0 0.6 0.2 AP 129 None BRAGFLO

PCS_T3 SAT_RBRN Cumulative 0.25 Median

0.2 0.0 0.6 0.2 AP 161 None BRAGFLO

PCS_T1 SAT_RGAS Uniform 0.2 - - 0.0 0.4 0.2 AP 129 None PRELHS

BRAGFLO

PCS_T2 SAT_RGAS Uniform 0.2 - - 0.0 0.4 0.2 AP 129 None BRAGFLO

PCS_T3 SAT_RGAS Uniform 0.2 - - 0.0 0.4 0.2 AP 161 None BRAGFLO

DRZ_ 1 CAP_MOD Constant 1 - - 1 1 1 CCA None BRAGFLO

DRZ_ PCS CAP_MOD Constant 1 - - 1 1 1 TBM None BRAGFLO

DRZ_ 1 COMP_RCK Constant 7.41E-10 - - 7.41E-10 7.41E-10 7.41E-10 CCA Pa-1 BRAGFLO

DRZ_ PCS COMP_RCK Constant 7.41E-10 - - 7.41E-10 7.41E-10 7.41E-10 TBM Pa-1 BRAGFLO

DRZ_ 1 KPT Constant 0.0 - - 0.0 0.0 0.0 CCA None BRAGFLO

DRZ_ PCS KPT Constant 0.0 - - 0.0 0.0 0.0 TBM None BRAGFLO

DRZ_ 1 PC_MAX Constant 1E08 - - 1E08 1E08 1E08 CCA Pa BRAGFLO

DRZ_ PCS PC_MAX Constant 1E08 - - 1E08 1E08 1E08 TBM Pa BRAGFLO

DRZ_ 1 PCT_A Constant 0.0 - - 0.0 0.0 0.0 CCA Pa BRAGFLO

DRZ_ PCS PCT_A Constant 0.0 - - 0.0 0.0 0.0 TBM Pa BRAGFLO

DRZ_ 1 PCT_EXP Constant 0.0 - - 0.0 0.0 0.0 CCA None BRAGFLO

DRZ_ PCS PCT_EXP Constant 0.0 - - 0.0 0.0 0.0 TBM None BRAGFLO

DRZ_ 1 PRMX_LOG Uniform -16.0 - - -19.4 -12.5 -16.0 CCA log(m2)

PRELHS

BRAGFLO
13

Table 1. Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material Name Property Name Distribution 

Type

Parameter Value Used in PCS-2012 PA First 

Use

Parameter 

Units Used in Code

Mean Other Minimum Maximum Default

DRZ_ 1 PRMY_LOG Uniform -16.0 - - -19.4 -12.5 -16.0 CCA log(m2) BRAGFLO

DRZ_ 1 PRMZ_LOG Uniform -16.0 - - -19.4 -12.5 -16.0 CCA log(m2) BRAGFLO

DRZ_ PCS PRMX_LOG Triangular -18.8160 Mode

-18.7496 -20.699 -17.0 -18.7496 TBM log(m2

)

PRELHS

BRAGFLO

DRZ_ PCS PRMY_LOG Triangular -18.8160 Mode

-18.7496 -20.699 -17.0 -18.7496 TBM log(m2

) BRAGFLO

DRZ_ PCS PRMZ_LOG Triangular -18.8160 Mode

-18.7496 -20.699 -17.0 -18.7496 TBM log(m2

) BRAGFLO

DRZ_ 1 PO_MIN Constant 1.01325

E05 - -

1.01325

E05

1.01325

E05

1.01325

E05 CCA Pa BRAGFLO

DRZ_ PCS PO_MIN Constant 1.01325

E05 - -

1.01325

E05

1.01325

E05

1.01325

E05 TBM Pa BRAGFLO

DRZ_ 1 PORE_DIS Constant 0.7 - - 0.7 0.7 0.7 CCA None BRAGFLO

DRZ_ PCS PORE_DIS Constant 0.7 - - 0.7 0.7 0.7 TBM None BRAGFLO

DRZ_ 1 POROSITY Cumulative 0.0211 Median

0.0129 0.0039 0.0548 0.0129 AP-132 None PRELHSBRAGFLO

DRZ_ PCS POROSITY Cumulative 0.0211 Median

0.0129 0.0039 0.0548 0.0129 AP-132 None BRAGFLO

DRZ_ 1 RELP_MOD Delta 4

Median

4

1 4 0 CCA None BRAGFLO

DRZ_ PCS RELP_MOD Delta 4

Median

4

1 4 0 TBM None BRAGFLO

DRZ_ 1 SAT_RBRN Constant 0.0 - - 0.0 0.0 0.0 CCA None BRAGFLO

DRZ_ PCS SAT_RBRN Constant 0.0 - - 0.0 0.0 0.0 TBM None BRAGFLO

DRZ_ 1 SAT_RGAS Constant 0.0 - - 0.0 0.0 0.0 CCA None BRAGFLO

DRZ_ PCS SAT_RGAS Constant 0.0 - - 0.0 0.0 0.0 TBM None BRAGFLO

Notes to Table 1

First Use Analyses:

CCA: Compliance Certification Analysis, 1996

TBM: Technical Baseline Migration Analysis, 2002

AP-129: Redesigned Panel Closure System Analysis, 2006

AP-132: 2009 Compliance Recertification Analysis, 2007

PC3R: Panel Closure Redesign and Repository Reconfiguration Analysis (AP-151), 2010

AP-161: PCS-2012 PA Analysis, 2012
14

Table 2. Justification Check for Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material 

Name

Property Name Parameter Type Parameter 

Data Entry 

ERMS No.

Supporting 

Document 

ERMS No.

Effective 

Date

Comments

PCS_T1 CAP_MOD Capillary pressure model 

number for the ROM Salt 

during time period T1

544680 554623 12/20/2010 ERMS 554623 states that capillary pressure Model 1 was selected for the ROM salt

during time period T1 to agree with the model selected for the DRZ above and below 

the ROM salt. ERMS 557721 (not cited in the PAPDB as a source for this parameter) 

adds that Model 1 is also used to avoid numerical difficulties in BRAGFLO. Model 1

is typically used when the threshold capillary pressure is set to zero, which deactivates 

the capillary pressure model. However, the parameter values accepted by EPA in 

ERMS 557396 included a value of 2 for the capillary pressure model, which would 

have activated that model. The EPA subsequently performed an analysis, which 

showed that an activated capillary pressure model made no significant difference in 

repository performance. See text discussion of two-phase flow parameters for 

additional information.

PCS_T2 CAP_MOD Capillary pressure model 

number for the ROM Salt 

during time period T2

554681 554623 12/20/2010 The comment for PCS_T1:CAP_MOD also applies to PCS_T2:CAP_MOD.

PCS_T3 CAP_MOD Capillary pressure model 

number for the ROM Salt 

during time period T3

557951 557721 7/17/2012 ERMS 557721 states that capillary pressure Model 1 was selected for the ROM salt

during time period T3 to agree with the model selected for the DRZ around the ROM 

salt and that Model 1 is also used to avoid numerical difficulties in BRAGFLO. Model 

1 is typically used when the threshold capillary pressure is set to zero, which 

deactivates the capillary pressure model. However, as stated above, the parameter 

values accepted by EPA in ERMS 557396 included a value of 2 for the capillary 

pressure model, which would have activated that model. The EPA subsequently 

performed an analysis, which showed that an activated capillary pressure model for 

the ROM salt and surrounding DRZ made no significant difference in repository 

performance. See text discussion of two-phase flow parameters for additional 

information.

PCS_T1 COMP_RCK Bulk compressibility of 

the ROM Salt during time 

period T1

543322 542894 3/27/2006 ERMS 542894 states that the value of this parameter was used for the crushed salt 

materials in the original shaft seal, that it is considered a reasonable estimate for 

reconsolidated salt, and that “the initial compressibility of the salt will be higher since 

it will be emplaced without compaction.” EPA has reviewed this parameter value and 

concurs that it is appropriate for reconsolidated salt. EPA believes that the use of this 

parameter for time periods T1 and T2, when the ROM salt likely has not fully 

reconsolidated, is acceptable because the ROM salt may be compacted upon 

emplacement.

PCS_T2 COMP_RCK Bulk compressibility of 

the ROM Salt during time 

period T2

543322 542894 3/27/2006 The comment for PCS_T1:COMP_RCK also applies to PCS_T2:COMP_RCK.

PCS_T3 COMP_RCK Bulk compressibility of 

the ROM Salt during time 

period T3

557951 557721 7/17/2012 ERMS 557721 refers to ERMS 557396 as the source of this parameter. ERMS 557396 

states that it was used for the crushed salt materials in the original shaft seal, but 

provides no further justification or references. EPA has reviewed this parameter value 

and concurs that it is appropriate for the reconsolidated salt that would be present 

during time period T3.
15

Table 2. Justification Check for Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material 

Name

Property Name Parameter Type Parameter 

Data Entry 

ERMS No.

Supporting 

Document 

ERMS No.

Effective 

Date

Comments

PCS_T1 KPT Flag for selecting the 

permeability used in 

calculating threshold 

capillary pressure for the 

ROM Salt during time 

period T1

543323 542894 3/27/2006 ERMS 542894 states that all WIPP PA materials use the same value of 0.0 for KPT 

and that this parameter is specific to the capillary pressure model used in WIPP PA. 

This parameter is a flag for using constant or varying permeability in the threshold 

pressure calculation and was originally set to 0.0, because varying permeability was 

not used in the CCA calculations. EPA understands that when KPT is set to zero, the 

threshold capillary pressure is recalculated for each new material and would therefore 

be appropriately recalculated for the new ROM salt materials during T1, T2, and T3. 

EPA therefore accepts a value of 0.0 for KPT. See text discussion of two-phase flow 

parameters for additional information.

PCS_T2 KPT Flag for selecting the 

permeability used in 

calculating threshold 

capillary pressure for the 

ROM Salt during time 

period T2

543338 542894 3/27/2006 The comment for PCS_T1:KPT also applies to PCS_T2:KPT.

PCS_T3 KPT Flag for selecting the 

permeability used in 

calculating threshold 

capillary pressure for the 

ROM Salt during time 

period T3

557951 557721

557396

7/17/2012 ERMS 557721 refers to ERMS 557396 as the source of this parameter. ERMS 557396 

states that all WIPP PA materials use the same values for KPT, but provides no 

further justification as to why this is appropriate for the ROM salt, which is a new 

material in WIPP PA. Despite the weakness in DOE’s justification, EPA understands 

that when KPT is set to zero, the threshold capillary pressure is recalculated for each 

new material, and would therefore be appropriately recalculated for the new ROM salt 

materials during T3. EPA therefore accepts a value of 0.0 for KPT. See text discussion 

of two-phase flow parameters for additional information.

PCS_T1 PC_MAX Maximum allowable

capillary pressure for the 

ROM Salt during time 

period T1

543324 542946

542894

3/27/2006 ERMS 542946 states that the values of PC_MAX and PO_MIN were reversed in 

ERMS 542894 and corrects that error. ERMS 542894 states that all WIPP PA 

materials use the same value for PC_MAX, but provides no justification for that 

value, nor does it refer to documents that do provide justification. However, EPA has 

reviewed the value of this parameter and found it to be reasonable. EPA also notes 

that capillary pressure can become very large at low brine saturations, and it is 

appropriate to limit the maximum value of this parameter to avoid numerical problems 

with BRAGFLO. EPA therefore concludes that the current value of this parameter is 

appropriate for PCS-2012. See text discussion of two-phase flow parameters for 

additional information.

PCS_T2 PC_MAX Maximum allowable 

capillary pressure for the 

ROM Salt during time 

period T2

543339 542946

542894

3/27/2006 The comment for PCS_T1:PC_MAX also applies to PCS_T2:PC_MAX.

PCS_T3 PC-MAX Maximum allowable 

capillary pressure for the 

ROM Salt during time 

period T3

557951 557721

557396

7/17/2012 ERMS 557721 refers to ERMS 557396 as the source of this parameter. ERMS 557396 

states that all WIPP PA materials use the same value for PC_MAX, but provides no 

justification for that value, nor does it refer to documents that do provide justification. 

In addition to the above comments for PC_MAX during T1 and T2, EPA notes that 

this parameter is not used when CAP_MOD is set to 1.0, as it was in PCS-2012, and is 

therefore acceptable. However, EPA expected CAP_MOD to be set to 2.0 for the 

ROM salt. See text discussion of two-phase flow parameters for additional 

information.
16

Table 2. Justification Check for Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material 

Name

Property Name Parameter Type Parameter 

Data Entry 

ERMS No.

Supporting 

Document 

ERMS No.

Effective 

Date

Comments

PCS_T1 PCT_A Threshold capillary 

pressure linear parameter 

for the ROM Salt during 

time period T1

554680 554623 12/20/2010 ERMS 554623 states that PCT_A was set to 0.0 for the PCS during time period T1 to 

agree with the model selected for the DRZ around the ROM salt. ERMS 557721 (not 

cited in the PAPDB as a source for this parameter) adds that PCT_A was also set to 

0.0 to avoid numerical difficulties in BRAGFLO. Setting PCT_A to zero sets the 

threshold capillary pressure to zero and deactivates the capillary pressure model. The 

parameter values accepted by EPA in ERMS 557396 included a value of 0.56 for 

PCT_A, which would have activated the capillary pressure model. The EPA 

subsequently performed an analysis which showed that an activated capillary pressure 

model made no significant difference in repository performance. See text discussion 

of two-phase flow parameters for additional information.

PCS_T2 PCT_A Threshold capillary 

pressure linear parameter 

for the ROM Salt during 

time period T2

554681 554623 12/20/2010 The comment for PCS_T1:PCT_A also applies to PCS_T2:PCT_A.

PCS_T3 PCT_A Threshold capillary 

pressure linear parameter 

for the ROM Salt during 

time period T3

557951 557721 7/17/2012 ERMS 557721 states that the value of PCS_T3:PCT_A was set to 0.0 in order to have 

consistency between the ROM salt and the surrounding DRZ, that a value of 0.0 was 

also used for the crushed salt component of the original shaft seal model, and that a 

value of 0.0 avoids numerical difficulties in BRAGFLO. EPA notes that setting 

PCT_A to zero is consistent with the selection of capillary pressure Model 1 and with 

capillary pressure modeling practice in the baseline PABC-2009. However, as stated 

above, the parameter values accepted by EPA in ERMS 557396 included a value of 

0.56 for PCT_A, which would have activated the capillary pressure model. The EPA 

subsequently performed an analysis which showed that an activated capillary pressure 

model made no significant difference in repository performance. See text discussion 

of two-phase flow parameters for additional information.

PCS_T1 PCT_EXP Threshold capillary 

pressure exponential 

parameter for the ROM 

Salt during time period 

T1

554680 554623

557721

12/20/2010 ERMS 554623 states that PCT_EXP was set to 0.0 for the ROM salt during time 

period T1 to agree with the model selected for the DRZ around the ROM salt, which 

deactivates capillary pressure. PCT_EXP is typically set to zero when PCT_A is set to 

zero. The parameter values accepted by EPA in ERMS 557396 included a value of 

0.56 for PCT_A and a value of -0.346 for PCT_EXP, which would have activated the 

capillary pressure model. The EPA subsequently performed an analysis which showed 

that an activated capillary pressure model made no significant difference in repository 

performance. See text discussion of two-phase flow parameters for additional 

information.

PCS_T2 PCT_EXP Threshold capillary 

pressure exponential 

parameter for the ROM 

Salt during time period 

T2

554681 554623

557721

12/20/2010 The comment for PCS_T1:PCT_EXP also applies to PCS_T2:PCT_EXP.

PCS_T3 PCT_EXP Threshold capillary 

pressure exponential 

parameter for the ROM 

Salt during time period 

T3

557951 557721 7/17/2012 ERMS 557721 states that the value of PCS_T3:PCT_EXP was set to 0.0 in order to 

have consistency between the ROM salt and the surrounding DRZ, and that a value of 

0.0 was also used for the crushed salt component of the original shaft seal model. EPA 

notes that setting PCT_EXP to zero is consistent with the selection of capillary 

pressure Model 1 and with capillary pressure modeling practice in the baseline PABC2009. However, the parameter values accepted by EPA in ERMS 557396 included 
17

Table 2. Justification Check for Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material 

Name

Property Name Parameter Type Parameter 

Data Entry 

ERMS No.

Supporting 

Document 

ERMS No.

Effective 

Date

Comments

values for PCT_A and PCT_EXP that would have activated the capillary pressure 

model. The EPA subsequently performed an analysis which showed that an activated 

capillary pressure model made no significant difference in repository performance. 

See text discussion of two-phase flow parameters for additional information.

PCS_T1 PO_MIN Minimum allowable brine 

pressure for the ROM 

Salt during time period 

T1

543327 542894

542946

3/27/2006 ERMS 542946 states that the values of PC_MAX and PO_MIN were reversed in 

ERMS 542894 and corrects that error. ERMS 542894 states that all WIPP PA 

materials use the same value for PO_MIN, but provides no justification for that value, 

nor does it refer to documents that do provide justification. EPA notes that this 

parameter is only used for capillary pressure Model 3, which was not used in PCS2012 or in PABC-2009. The value of this parameter, therefore, has no impact on the 

PA results.

PCS_T2 PO_MIN Minimum allowable brine 

pressure for the ROM 

Salt during time period 

T2

543342 542894

542946

3/27/2006 The comment for PCS_T1:PO_MIN also applies to PCS_T2:PO_MIN.

PCS_T3 PO_MIN Minimum allowable brine 

pressure for the ROM 

Salt during time period 

T3

557951 557721

557396

7/17/2012 ERMS 557721 refers to ERMS 557396 as the source of this parameter. ERMS 557396 

states that all WIPP PA materials use the same value for PO_MIN, but provides no 

justification for that value, nor does it refer to documents that do provide justification. 

EPA notes that this parameter is only used when CAP_MOD is set to 3.0. Because 

only capillary pressure Models 1 or 2 have been contemplated for PCS-2012, this 

parameter was not used.

PCS_T1 PORE_DIS Brooks-Corey pore 

distribution parameter for 

the ROM Salt during time 

period T1

543328 542894 3/27/2006 ERMS 542894 states that all WIPP salt-related parameters for the original shaft seal 

model use relative permeability Model 4, a modified Brooks-Corey model, which 

requires this property. EPA has reviewed the range and distribution for this parameter 

and found them to be reasonable.

PCS_T2 PORE_DIS Brooks-Corey pore 

distribution parameter for 

the ROM Salt during time 

period T2

543343 542894 3/27/2006 The comment for PCS_T1: PORE_DIS also applies to PCS_T2: PORE_DIS.

PCS_T3 PORE_DIS Brooks-Corey pore 

distribution parameter for 

the ROM Salt during time 

period T3

557951 557721

557396

7/17/2012 ERMS 557721 refers to ERMS 557396 as the source of this parameter. ERMS 557396 

states that the crushed salt materials for the original shaft seal model use the same 

values and distributions for PORE_DIS as used in PCS-2012 and in PABC-2009. EPA 

has reviewed the range and distribution for this parameter and found them to be 

reasonable.

PCS_T1 POROSITY Porosity of the ROM Salt 

during time period T1

557949 557721

557396

7/17/2012 ERMS 557721 refers to ERMS 557396 as the source of this parameter. ERMS 557396 

states that, depending on the method of emplacement, the initial porosity of the ROM 

salt will vary between 20% and 35%. The range of PCS porosity for T1 was 

determined at the T1 midpoint time of 50 years, when the ROM salt porosity predicted 

by JAS3D modeling is a low of 6.6% for an initial porosity of 20% and a high of 

18.7% for an initial porosity of 35%. EPA acknowledges that considerable uncertainty 

is associated with the rate of ROM salt consolidation in a panel closure and accepts 

this range and the underlying uniform distribution as providing adequate estimates of 

ROM salt porosities for PCS-2012 during time period T1. Also see text discussion of 

ROM salt porosity and permeability.
18

Table 2. Justification Check for Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material 

Name

Property Name Parameter Type Parameter 

Data Entry 

ERMS No.

Supporting 

Document 

ERMS No.

Effective 

Date

Comments

PCS_T2 POROSITY Porosity of the ROM Salt 

during time period T2

557950 557721

557396

7/23/2012 ERMS 557721 refers to ERMS 557396 as the source of this parameter. ERMS 557396 

states that the range of ROM salt porosity values for T2 is based on JAS3D modeling 

results, on consideration of 0.05 as the expected value, and on maintaining a range 

that is similar to the range for intact halite. EPA acknowledges that considerable 

uncertainty is associated with the rate of ROM salt consolidation in a panel closure 

and accepts this range and the underlying uniform distribution as providing adequate

estimates of ROM salt porosities for PCS-2012 during time period T2. Also see text 

discussion of ROM salt porosity and permeability.

PCS_T3 POROSITY Porosity of the ROM Salt

during time period T3

557951 557721

557396

7/17/2012 ERMS 557721 refers to ERMS 557396 as the source of this parameter. ERMS 557396 

states that the ROM salt T3 porosity is assumed to be equal to the porosity for intact 

halite and is therefore the same as the porosity range for intact halite in WIPP PA.

EPA agrees that the porosity of the ROM salt will, over time, approach that of intact 

halite and agrees that, based on modeling and analog studies, the ROM salt T3 

porosity range and underlying uniform distribution provide adequate estimates 

appropriate for the PCS-2012 PA. Also see text discussion of ROM salt porosity and 

permeability.

PCS_T1 PRMX_LOG Permeability of the ROM 

Salt in the X-direction 

during time period T1

557949 557721 7/17/2012 The cited source ERMS 557721 refers to ERMS 557396 as the source of the original 

range, -18.7 to -12 log(m2), for this parameter. ERMS 557396 states that this 

permeability range corresponds to laboratory data for the porosity range of 0.066 to 

0.187 assigned to the parameter PCS_T1:POROSITY. ERMS 557721 refers to a 2012 

DOE response to EPA questions (ERMS 557865) as the source of a revised lower 

value of the sampled range for this parameter, -21 log(m2). However, this revised 

lower value was based on laboratory data that was reviewed by DOE in ERMS 

557396 and rejected when developing the original range. See text section on ROM 

salt porosity and permeability for additional discussion of this inconsistency. EPA 

accepts the assumption that the ROM salt material is isotropic, with the same 

permeabilities in the X-, Y-, and Z-directions.

PCS_T1 PRMY_LOG Permeability of the ROM 

Salt in the Y-direction 

during time period T1

557949 557721 7/17/2012 The comment for PCS_T1:PRMX_LOG also applies to PCS_T1:PRMY_LOG.

PCS_T1 PRMZ_LOG Permeability of the ROM 

Salt in the Z-direction 

during time period T1

557949 557721 7/17/2012 The comment for PCS_T1:PRMX_LOG also applies to PCS_T1:PRMZ_LOG.

PCS_T2 POR2PERM Distribution used to 

calculate permeability 

from porosity values 

during time period T2

557950 557721

537396

7/23/2012 ERMS 557721 refers to ERMS 557396 as the source of this parameter. ERMS 557396 

adequately describes the sampling process and the derivation of the ROM salt 

permeability as a function of porosity, but unfortunately does not mention the property 

POR2PERM. POR2PERM is, in fact, the same as the parameter alpha in ERMS 

557396 Equation 2. Except for this lapse in transparency, EPA believes that 

POR2PERM (or alpha) was adequately described and justified, and provides an 

appropriate mechanism for incorporating uncertainty into a correlation of permeability 

and porosity. See the text discussion of PCS porosity and permeability for additional 

information.
19

Table 2. Justification Check for Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material 

Name

Property Name Parameter Type Parameter 

Data Entry 

ERMS No.

Supporting 

Document 

ERMS No.

Effective 

Date

Comments

PCS_T2 PRMX_LOG Permeability of the ROM 

Salt in the X-direction 

during time period T2

557950 557721 7/23/2012 ERMS 557721 refers to ERMS 557396 as the source of this parameter. The constant 

PCS_T2: PRMX_LOG default value is identified as the average of the minimum and 

maximum values described for T2 in ERMS 557396, Table 5. The default value is 

retrieved from the database and then set equal to the ROM salt permeability calculated 

for time period T2 based on the T2 porosity and POR2PERM value. This same 

permeability value is assigned to the X-, Y-, and Z-directions. The Agency accepts 

this process for determining permeability values and considers the assumption of 

isotropic permeability to be reasonable. See the text discussion of ROM salt porosity 

and permeability for additional information.

PCS_T2 PRMY_LOG Permeability of the ROM 

Salt in the Y-direction 

during time period T2

557950 557721 7/23/2012 The comment for PCS_T2: PRMX_LOG also applies to PCS_T2: PRMY_LOG.

PCS_T2 PRMZ_LOG Permeability of the ROM 

Salt in the Z-direction 

during time period T2

557950 557721 7/23/2012 The comment for PCS_T2: PRMX_LOG also applies to PCS_T2: PRMZ_LOG.

PCS_T3 POR2PERM Distribution used to 

calculate permeability 

from sampled porosity 

values during time period 

T3

557951 557721

557396

7/17/2012 The comment for PCS_T2:POR2PERM also applies to PCS_T3:POR2PERM.

PCS_T3 PRMX_LOG Permeability of the ROM 

Salt in the X-direction 

during time period T3

557951 557721 7/17/2012 ERMS 557721 refers to ERMS 557396 as the source of this parameter. The constant 

PCS_T3: PRMX_LOG default value is identified as the average of the minimum and 

maximum values described for T3 in ERMS 557396, Table 5. The default value is 

retrieved from the database and then set equal to the ROM salt permeability calculated 

for time period T3 based on the T3 porosity and POR2PERM value. This is the same 

process as used for calculating the PCS_T2: PRMX_LOG value. The same T3 

permeability value is assigned to the X-, Y-, and Z-directions. The Agency accepts 

this process for determining permeability values and considers the assumption of 

isotropic permeability to be reasonable. See the text discussion of ROM salt porosity 

and permeability for additional information.

PCS_T3 PRMY_LOG Permeability of the ROM 

Salt in the Y-direction 

during time period T3

557951 557721 7/17/2012 The comment for PCS_T3: PRMX_LOG also applies to PCS_T3: PRMY_LOG.

PCS_T3 PRMZ_LOG Permeability of the ROM 

Salt in the Z-direction 

during time period T3

557951 557721 7/17/2012 The comment for PCS_T3: PRMX_LOG also applies to PCS_T3: PRMZ_LOG.

PCS_T1 RELP_MOD Relative permeability 

model number for the 

ROM Salt during time 

period T1

543333 542894 3/27/2006 ERMS 542894 states that all WIPP salt-related parameters for the original shaft seal 

model use relative permeability Model 4, a modified Brooks-Corey model. EPA has 

reviewed this model and found it to be appropriate for the ROM salt .

PCS_T2 RELP_MOD Relative permeability 

model number for the 

ROM Salt during time 

period T2

543348 542894 3/27/2006 The comment for PCS_T1:RELP_MOD also applies to PCS_T2:RELP_MOD.
20

Table 2. Justification Check for Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material 

Name

Property Name Parameter Type Parameter 

Data Entry 

ERMS No.

Supporting 

Document 

ERMS No.

Effective 

Date

Comments

PCS_T3 RELP_MOD Relative permeability 

model number for the 

ROM Salt during time 

period T2

557951 557721

557396

7/17/2012 ERMS 557721 refers to ERMS 557396 as the source of this parameter. ERMS 557396 

states that the two-phase flow model for the ROM salt PCS uses the modified BrooksCorey model, which corresponds to relative permeability Model 4. EPA believes that 

the choice of Model 4 for the ROM salt PCS is appropriate and consistent with the use 

of Model 4 in the baseline PABC-2009.

PCS_T1 SAT_IBRN Initial brine saturation of 

the ROM Salt at the 

beginning of time period 

T1

557949 557721 7/17/2012 ERMS 557721 states that a range of initial brine saturations of the ROM salt was used 

in the PCS-2012 PA to account for uncertainty in the method to be used in emplacing

the ROM salt. The low end of the range is based on loose emplacement with no added 

moisture. The high end of the range assumes the salt is compacted to 20% porosity 

with 1% by weight added moisture. The density of brine was assumed to be 

1220 kg/m3and the density of halite was assumed to be 2140 kg/m3. The Agency 

accepts this range; however, see text discussion of two-phase flow parameters.

PCS_T1 SAT_RBRN Residual brine saturation 

of the ROM Salt during 

time period T1

543334 542894 3/27/2006 ERMS 542894 states that all WIPP salt-related parameters for the original shaft seal 

model use the same probability distribution and values to model residual brine 

saturation, and that this distribution is also appropriate for the ROM salt materials, but 

provides no further justification or references. Because this distribution was also used 

in PABC-2009, EPA considers it appropriate to retain it for PCS-2012 to simplify 

comparison of results. However, see text discussion of two-phase flow parameters.

PCS_T2 SAT_RBRN Residual brine saturation 

of the ROM Salt during 

time period T2

543349 542894 3/27/2006 The comment for PCS_T1:SAT_RBRN also applies to PCS_T2:SAT_RBRN.

PCS_T3 SAT_RBRN Residual brine saturation 

of the ROM Salt during 

time period T3

557951 557721

557396

7/17/2012 ERMS 557721 refers to ERMS 557396 as the source of this parameter. ERMS 557396 

states that the residual brine saturation for the ROM salt uses the same values and 

distribution as for the crushed salt component of the shaft seals, and were defined for 

the CCA based on a literature review and on professional judgment. A reference is 

provided to the original CCA justification documentation. EPA accepts these values 

and distribution as appropriate for comparative purposes in PCS-2012. However, see 

text discussion of two-phase parameters for additional information.

PCS_T1 SAT_RGAS Residual gas saturation of 

the ROM Salt during time 

period T1

543335 542894 3/27/2006 ERMS 542894 states that all WIPP salt-related parameters for the original shaft seal 

model use the same probability distribution and values to model residual gas

saturation, and that this distribution is also appropriate for the ROM salt materials, but 

provides no further justification or references. Because this distribution was also used 

in PABC-2009, EPA considers it appropriate to retain it for PCS-2012 to simplify 

comparison of results. However, see text discussion of two-phase flow parameters.

PCS_T2 SAT_RGAS Residual gas saturation of 

the ROM Salt during time 

period T2

543350 542894 3/27/2006 The comment for PCS_T1:SAT_RGAS also applies to PCS_T2:SAT_RGAS.

PCS_T3 SAT_RGAS Residual gas saturation of 

the ROM Salt during time 

period T3

557951 557721

557396

7/17/2012 ERMS 557721 refers to ERMS 557396 as the source of this parameter. ERMS 557396 

states that the residual gas saturation for the ROM salt uses the same values and 

distribution as for the crushed salt component of the shaft seals, and were defined for 

the CCA based on a literature review and on professional judgment. A reference is 

provided to the original CCA justification documentation. EPA accepts these values 

and distribution appropriate for comparative purposes in PCS-2012. However, see text 

discussion of two-phase parameters for additional information.
21

Table 2. Justification Check for Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material 

Name

Property Name Parameter Type Parameter 

Data Entry 

ERMS No.

Supporting 

Document 

ERMS No.

Effective 

Date

Comments

DRZ_ 1 CAP_MOD Capillary pressure model 

number for the PCS DRZ 

during time periods T1 

and T2

545696 545496 3/01/2007 EPA found no mention of parameter DRZ_1:CAP_MOD in the cited source document 

ERMS 545496. Despite this lack of traceability, EPA concludes that the choice of 

Model 1 for the capillary pressure model is appropriate, because it is consistent with 

SNL practice of selecting Model 1 when the threshold capillary pressure is set to zero. 

See text discussion of two-phase flow parameters.

DRZ_ PCS CAP_MOD Capillary pressure model 

number for the PCS DRZ 

during time period T3

520524 520524 2/14/2002 ERMS 520524 states that, except for permeabilities, the property values assigned to 

the DRZ_PCS are the same as those used for the PAVT material DRZ_1, but does not 

refer to documents that justify those values. Material DRZ_1 was defined for the 

PAVT and most subsequent analyses as the DRZ from 0 to 10,000 years. Despite the 

redefinition of the time frame for this material to 0 to 200 years in PCS-2012, EPA 

accepts the choice of Model 1 for the capillary pressure model as appropriate, because 

it is consistent with SNL’s practice of selecting Model 1 when the threshold capillary 

pressure is set to zero. See text discussion of two-phase flow parameters.

DRZ_ 1 COMP_RCK Bulk compressibility of 

the PCS DRZ during time 

periods T1 and T2

232871 232288 2/12/1996 ERMS 232288 identifies the value of this parameter that was used in PCS-2012 and in 

PABC-2009 as the bulk compressibility of the DRZ around a waste panel for times 

greater than zero. Although the conceptual model of the DRZ around a waste panel is 

described and this compressibility value is asserted to be consistent with the 

conceptual model, no specific technical justification of this parameter value is 

presented, either for its original application to the DRZ around a waste panel or to its 

current application to the DRZ around a ROM salt panel closure. However, EPA 

accepts this compressibility value to minimize differences between PCS-2012 and the 

baseline PABC-2009, and simplify comparison of results.

DRZ_ PCS COMP_RCK Bulk compressibility of 

the PCS DRZ during time 

period T3

520524 520524 2/14/2002 ERMS 520524 states that, except for permeabilities, the property values assigned to 

the DRZ_PCS are the same as those used for the PAVT material DRZ_1, but does not 

refer to documents that justify those values. Material DRZ_1 was defined for the 

PAVT and most subsequent analyses as the DRZ from 0 to 10,000 years. Despite the 

redefinition of the time frame for this material in PCS-2012, EPA has reviewed and 

accepts the assigned value as representative of the bulk compressibility of nearly 

intact halite.

DRZ_ 1 KPT Flag for selecting the 

permeability used in 

calculating threshold 

capillary pressure for the 

PCS DRZ during time 

periods T1 and T2

232870 235271 4/09/1996 ERMS 235271 describes this parameter as a flag for using either constant or varying 

permeability in the threshold pressure calculation, and states that the value should be 

set to 0.0 because varying permeability will not be used in the CCA calculations. EPA 

notes that at the time this justification was prepared, material DRZ_1 was defined as 

representing the waste panel DRZ from time zero to 10,000 years. However, EPA 

accepts setting KPT to zero for PCS-2012, because it is understood that the threshold 

capillary pressure is recalculated by BRAGFLO for each new material, and would 

therefore provide a threshold pressure relevant to the permeability of material DRZ_1 

for time periods T1 and T2. See text discussion of two-phase flow parameters for 

additional information.

DRZ_ PCS KPT Flag for selecting the 

permeability used in 

calculating threshold 

capillary pressure for the 

PCS DRZ during time 

period T3

520524 520524 2/14/2002 ERMS 520524 states that, except for permeabilities, the property values assigned to 

the DRZ_PCS are the same as those used for the PAVT material DRZ_1, but does not 

refer to documents that justify those values. Material DRZ_1 was defined for the 

PAVT and most subsequent analyses as the DRZ from 0 to 10,000 years. Despite the 

redefinition of the time frame for this material in PCS-2012, EPA accepts setting KPT 

to zero for PCS-2012, because it is understood that the threshold capillary pressure is 
22

Table 2. Justification Check for Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material 

Name

Property Name Parameter Type Parameter 

Data Entry 

ERMS No.

Supporting 

Document 

ERMS No.

Effective 

Date

Comments

recalculated by BRAGFLO for each new material, and would therefore provide a 

threshold pressure relevant to the permeability of material DRZ_PCS for time period 

T3. See text discussion of two-phase flow parameters for additional information.

DRZ_ 1 PC_MAX Maximum allowable 

capillary pressure for the 

PCS DRZ during time 

periods T1 and T2

232899 238568 2/05/1996 The cited source ERMS 238568 identifies this parameter as one of many “legacy 

parameters” and states that there are numerous sources for these parameters, but that 

the majority of parameter values can be considered as the choice of the PA analyst. A 

specific source for this parameter was not provided. Because PC_MAX represents a 

specific cutoff pressure in capillary pressure calculations, EPA considers that its 

magnitude should have been specifically justified. However, EPA has reviewed the 

value of this parameter and found it to be reasonable.

DRZ_ PCS PC_MAX Maximum allowable 

capillary pressure for the 

PCS DRZ during time 

period T3

520524 520524 2/14/2002 ERMS 520524 states that, except for permeabilities, the property values assigned to 

the DRZ_PCS are the same as those used for the PAVT material DRZ_1, but does not 

refer to documents that justify those values. Material DRZ_1 was defined for the 

PAVT and most subsequent analyses as the DRZ from 0 to 10,000 years. Despite the 

redefinition of the time frame for this material in PCS-2012, EPA has reviewed the 

value of this parameter and found it to be reasonable.

DRZ_ 1 PCT_A Threshold capillary

pressure linear parameter 

for the PCS DRZ during 

time periods T1 and T2

236559 232288 2/22/1996 The assigned value of zero for PCT_A in PCS-2012 sets the threshold capillary 

pressure of the DRZ to zero during time periods T1 and T2. The material DRZ_1 

originally represented the DRZ around a waste panel, which was conceptually 

considered to not heal and retain open vertical fractures throughout the regulatory time 

frame because of the effect of gas pressurization. ERMS 232288 correctly states that a 

zero threshold capillary pressure is reasonable for a fractured material. EPA therefore 

considers a value of zero for PCT_A to be appropriate for material DRZ_1 as used in 

PCS-2012, because it represents a fractured halite that has not fully healed. EPA also 

accepts a value of zero for this parameter to facilitate a comparison of results because 

it was used in both PCS-2012 and PABC-2009. See text discussion of two-phase flow 

parameters for additional information.

DRZ_ PCS PCT_A Threshold capillary 

pressure linear parameter 

for the PCS DRZ during 

time period T3

520524 520524 2/14/2002 ERMS 520524 states that, except for permeabilities, the property values assigned to 

the DRZ_PCS are the same as those used for the PAVT material DRZ_1, but does not 

refer to documents that justify those values. Material DRZ_1 was defined for the 

PAVT and most subsequent analyses as the DRZ from 0 to 10,000 years. Despite the 

redefinition of the time frame for this material in PCS-2012, EPA accepts a value of 

zero for PCT_A to facilitate a comparison of results because it was used in both PCS2012 and PABC-2009. However, a value of zero may not be fully appropriate for the 

PCS DRZ, because it represents a healed rather than a fractured material. See text 

discussion of two-phase flow parameters for additional information.

DRZ_ 1 PCT_EXP Threshold capillary 

pressure exponential 

parameter for the PCS 

DRZ during time periods 

T1 and T2

236560 232288 2/22/1996 The assigned value of zero in ERMS 232288 for PCT_EXP is consistent with the 

assigned value of zero for PCT_A, which sets the threshold capillary pressure to zero. 

The comment for DRZ_1:PCT_A therefore also applies to DRZ_1:PCT_EXP. EPA 

accepts a value of zero for this parameter to facilitate comparison of results, because it 

was used in both PCS-2012 and PABC-2009. See text discussion of two-phase flow 

parameters for additional information.
23

Table 2. Justification Check for Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material 

Name

Property Name Parameter Type Parameter 

Data Entry 

ERMS No.

Supporting 

Document 

ERMS No.

Effective 

Date

Comments

DRZ_ PCS PCT_EXP Threshold capillary 

pressure exponential 

parameter for the PCS 

DRZ during time period 

T3

520524 520524 2/14/2002 ERMS 520524 states that, except for permeabilities, the property values assigned to 

the DRZ_PCS are the same as those used for the PAVT material DRZ_1, but does not 

refer to documents that justify those values. EPA accepts a value of zero for 

DRZ_PCS:PCT_EXP for reasons stated above for DRZ_1:PCT_EXP. See text 

discussion of two-phase flow parameters for additional information.

DRZ_ 1 PRMX_LOG X-direction permeability 

of the PCS DRZ during 

time periods T1 and T2

522016 519513 2/14/2002 The range and distribution of permeabilities assigned to DRZ_1 is the same as those 

assigned to the DRZ around the waste panels in the PAVT and in subsequent analyses. 

ERMS 519513 traces the origin of this range and distribution to EPA-mandated values 

for the PAVT and provides a brief summary of their justification. ERMS 519513 also 

presents additional data that support this range. EPA accepts this range and 

distribution as applicable to T1 and T2 because, like the DRZ around a waste panel, 

the PCS DRZ may not be fully healed during these time periods. EPA also accepts the 

assumption of an isotropic permeability for this material.

DRZ_ 1 PRMY_LOG Y-direction permeability 

of the PCS DRZ during 

time periods T1 and T2

522016 519513 2/14/2002 The comment for DRZ_1:PRMX_LOG also applies to DRZ_1:PRMY_LOG.

DRZ_ 1 PRMZ_LOG Z-direction permeability 

of the PCS DRZ during 

time periods T1 and T2

522016 519513 2/14/2002 The comment for DRZ_1:PRMX_LOG also applies to DRZ_1:PRMZ_LOG.

DRZ_ PCS PRMX_LOG X-direction permeability 

of the PCS DRZ during 

time period T3

520524

555599

520524 2/14/2002

5/24/2011

ERMS 520524 refers to AP-086 (ERMS 520612) for a detailed description and 

justification of material DRZ_PCS. This material was originally defined as the healed 

DRZ above the Option D concrete monolith. ERMS 520612 states that the DRZ above

the monolith would heal quickly and would likely have slightly higher permeability 

than intact halite because it is relatively thin and may have small-scale 

heterogeneities, such as thin clay seams, that would increase its permeability. The 

permeability range for intact halite is -24 to -21 log(m2). Material DRZ_PCS was 

given the same permeability range as the Option D concrete monolith, because it met 

the criterion of being slightly higher than for intact halite, and so that the DRZ and 

concrete monolith would act as a composite system. EPA agrees that healing of the 

DRZ around the ROM salt would likely be essentially complete by time period T3,

and the use of this permeability range for PCS-2012 is therefore acceptable for 

purposes of comparison with PABC-2009. EPA also accepts the assumption of an 

isotropic permeability for this material. However, the healing and consequent 

permeability reduction of the PCS DRZ is linked with the healing of the ROM salt . 

See text discussion of DRZ porosity and permeability.

DRZ_ PCS PRMY_LOG Y-direction permeability 

of the PCS DRZ during 

time period T3

520524

555599

520524 2/14/2002

5/24/2011

The comment for DRZ_PCS:PRMX_LOG also applies to DRZ_PCS:PRMY_LOG.

DRZ_ PCS PRMZ_LOG Z-direction permeability 

of the PCS DRZ during 

time period T3

520524

555599

520524 2/14/2002

5/24/2011

The comment for DRZ_PCS:PRMX_LOG also applies to DRZ_PCS:PRMZ_LOG.
24

Table 2. Justification Check for Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material 

Name

Property Name Parameter Type Parameter 

Data Entry 

ERMS No.

Supporting 

Document 

ERMS No.

Effective 

Date

Comments

DRZ_ 1 PO_MIN Minimum allowable brine 

pressure for the PCS DRZ 

during time periods T1 

and T2

232903 236051 2/22/1996 The cited source document ERMS 236051 identifies only the value of this parameter 

used in PCS-2012. It does not justify that value, nor does it refer to a document that 

does provide justification. However, EPA understands that this parameter is used only 

in capillary pressure Model 3, which was not used in either PCS-2012 or in PABC2009. EPA therefore considers this parameter value to be acceptable despite the lack 

of justification.

DRZ_ PCS PO_MIN Minimum allowable brine 

pressure for the PCS DRZ 

during time period T3

520524 520524 2/14/2002 ERMS 520524 states that, except for permeabilities, the property values assigned to 

the DRZ_PCS are the same as those used for the PAVT material DRZ_1, but does not 

refer to documents that justify those values. EPA understands that this parameter is 

used only in capillary pressure Model 3, which was not used in either PCS-2012 or in 

PABC-2009. EPA therefore considers this parameter value to be acceptable despite 

the lack of justification.

DRZ_ 1 PORE_DIS Brooks-Corey pore 

distribution parameter for 

the PCS DRZ during time 

periods T1 and T2

232901 232288 2/12/1996 ERMS 232288 identifies the assigned constant value of 0.7 for this parameter as the 

median for Salado halite; however, for the ROM salt PCS, this parameter is sampled 

from a cumulative distribution with a median value of 0.94. EPA accepts a constant 

value of 0.7 for this parameter to facilitate comparison of results because it was used 

in both PCS-2012 and PABC-2009. However, the difference in median values and the 

use of a constant value for the PCS DRZ versus a distributed value for the ROM salt 

PCS should be justified.

DRZ_ PCS PORE_DIS Brooks-Corey pore 

distribution parameter for 

the PCS DRZ during time 

period T3

520524 520524 2/14/2002 ERMS 520524 states that, except for permeabilities, the property values assigned to 

the DRZ_PCS are the same as those used for the PAVT material DRZ_1, but does not 

refer to documents that justify those values. Material DRZ_1 was defined for the 

PAVT and most subsequent analyses as the DRZ from 0 to 10,000 years. Despite the 

redefinition of the time frame for this material in PCS-2012, EPA accepts a constant 

value of 0.7 for this parameter for the reasons given above for DRZ_1:PORE_DIS.

DRZ_ 1 POROSITY Porosity of the PCS DRZ 

during time periods T1 

and T2

545795 545755 4/10/2007 ERMS 545755 corrects an error in the maximum value of parameter 

S_HALITE:POROSITY and also lists the porosity range and distribution used for

DRZ_1:POROSITY, but provides no justification for those parameters, nor does it 

refer to a document that does provide justification. However, ERMS 557396 states 

that the initial porosity of the PCS DRZ is set equal to the porosity of the DRZ around 

the waste panels. EPA accepts this approach as reasonable despite a lack of 

justification in the cited source document.

DRZ_ PCS POROSITY Porosity of the PCS DRZ 

during time period T3

545795 545755 4/10/2007 ERMS 545755 corrects an error in the maximum value of parameter 

S_HALITE:POROSITY and also lists the porosity range and distribution used for 

DRZ_PCS:POROSITY, but provides no justification for those parameters, nor does it 

refer to a document that does provide justification. However, ERMS 557396 states 

that the long-term value of DRZ_PCS:POROSITY is the same as the porosity of the 

DRZ around the Option D panel closure (which is also the same as the initial DRZ_1 

porosity around the panel closures). Although the long-term DRZ porosity would be 

expected to be smaller than the initial porosity due to consolidation effects, EPA 

accepts the range and distribution for the DRZ_PCS porosity used in PCS-2012,

because they were also used in PABC-2009 and therefore facilitate a comparison of 

results.
25

Table 2. Justification Check for Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material 

Name

Property Name Parameter Type Parameter 

Data Entry 

ERMS No.

Supporting 

Document 

ERMS No.

Effective 

Date

Comments

DRZ_ 1 RELP_MOD Relative permeability 

model number for the 

PCS DRZ during time 

periods T1 and T2

232910 232288 2/13/1996 ERMS 232288 identifies the two-phase flow model as “Brooks/Corey (same as 

Halite).” EPA considers it appropriate to use the same model for DRZ_1 as for the 

intact halite. However, this parameter is shown in the cited PDE form and the PAPDB 

as distributed using a Delta function with a probability of 0.33 for a value of 1 (which 

selects Permeability Model 1, a modified van Genuchten-Parker model) and a 

probability of 0.67 for a value of 4 (which selects Permeability Model 4, a modified 

Brooks-Corey model). Despite specifying a distributed value in the database, this 

distribution was not sampled and a value of 4 was returned for every vector. Although 

EPA accepts this result because Model 4 is the desired Brooks-Corey model, the 

inconsistencies between the database, the justification, and the actual sampling 

practice are not acceptable. See text discussion of Table 3 for more information.

DRZ_ PCS RELP_MOD Relative permeability 

model number for the 

PCS DRZ during time 

period T3

520524 520524 2/14/2002 ERMS 520524 states that, except for permeabilities, the property values assigned to 

the DRZ_PCS are the same as those used for the PAVT material DRZ_1, but does not 

refer to documents that justify those values. Although this parameter is shown in the 

PDE form and the PAPDB as distributed using a Delta function with a probability of 

0.33 for a value of 1 (which selects Permeability Model 1) and a probability of 0.67 

for a value of 4 (which selects Permeability Model 4), a value of 4 was returned for 

every vector. Although EPA accepts this result because Model 4 is the desired 

Brooks-Corey model, the inconsistency between the database and the actual sampling 

practice is not acceptable. See text discussion of Table 3 for more information.

DRZ_ 1 SAT_RBRN Residual brine saturation 

of the PCS DRZ during 

time periods T1 and T2

232912 238568 12/05/1996 The cited source ERMS 238568 identifies this parameter as one of many “legacy 

parameters” and states that there are numerous sources for those parameters, but the 

majority can be considered as the choice of the PA analyst. A specific source for this 

parameter was not provided. Because SAT_RBRN represents a cutoff saturation 

below which brine cannot flow, EPA considers that its magnitude should have been 

specifically justified. EPA accepts the assigned constant value of zero for this 

parameter to facilitate comparison of results, because it was used in both PCS-2012 

and PABC-2009. However, EPA notes that while a value of zero may be appropriate 

for a fractured medium and may therefore be justified for a fractured DRZ during time 

periods T1 and T2, it may not be appropriate for consolidated materials. In addition, 

SAT_RBRN is treated as a constant for the DRZ_PCS while it was sampled over a 

range from zero to 0.6 for the ROM salt material. The lack of consistent treatment and 

the appropriateness of a zero value should be justified. EPA accepts the value of 

DRZ_1:SAT_RBRN used in PCS-2012 despite a lack of justification, because it was 

also used in PABC-2009 and facilitates comparison of results. Also see text discussion 

of two-phase flow parameters.

DRZ_ PCS SAT_RBRN Residual brine saturation 

of the PCS DRZ during 

time period T3

520524 520524 2/14/2002 ERMS 520524 states that, except for permeabilities, the property values assigned to 

the DRZ_PCS are the same as those used for the PAVT material DRZ_1, but does not 

refer to documents that justify those values. Material DRZ_1 was defined for the 

PAVT and most subsequent analyses as the DRZ from 0 to 10,000 years. In 

considering the redefinition of the time frame for this material in PCS-2012, EPA

notes that while a value of zero may be appropriate for a fractured medium, it may not 

be appropriate for a consolidated and healed DRZ, such as is conceptually assumed 

for the DRZ_PCS during T3. In addition, SAT_RBRN is treated as a constant for the 

DRZ_PCS while it was sampled over a range from zero to 0.6 for the ROM salt 
26

Table 2. Justification Check for Parameters Used in the PCS-2012 PA that have Changed since PABC-2009

Material 

Name

Property Name Parameter Type Parameter 

Data Entry 

ERMS No.

Supporting 

Document 

ERMS No.

Effective 

Date

Comments

material. The lack of consistent treatment and the appropriateness of a zero value 

should be justified. EPA accepts the value of DRZ_PCS:SAT_RBRN used in PCS2012 despite a lack of justification, because it was also used in PABC-2009 and 

facilitates comparison of results. Also see text discussion of two-phase flow 

parameters

DRZ_ 1 SAT_RGAS Residual gas saturation of 

the PCS DRZ during time 

periods T1 and T2

232913 238568 12/05/1996 The cited source ERMS 238568 identifies this parameter as one of many “legacy 

parameters” and states that there are numerous sources for those parameters, but the 

majority can be considered as the choice of the PA analyst. A specific source for this 

parameter was not provided. Because SAT_RGAS represents a specific cutoff 

saturation below which gas cannot flow, EPA considers that its magnitude should 

have been specifically justified. EPA accepts the assigned constant value of zero for 

this parameter to facilitate comparison of results because it was used in both PCS2012 and PABC-2009. However, EPA notes that a value of zero may not be 

appropriate for consolidated materials, and that SAT_RGAS was sampled over a 

range from zero to 0.4 for the ROM salt material. The lack of consistent treatment and 

appropriateness of a zero value should be justified. Also see text discussion of twophase flow parameters.

DRZ_ PCS SAT_RGAS Residual gas saturation of 

the PCS DRZ during time 

period T3

520524 520524 2/14/2002 ERMS 520524 states that, except for permeabilities, the property values assigned to 

the DRZ_PCS are the same as those used for the PAVT material DRZ_1, but does not 

refer to documents that justify those values. Material DRZ_1 was defined for the 

PAVT and most subsequent analyses as the DRZ from 0 to 10,000 years. In 

considering the redefinition of the time frame for this material in PCS-2012, EPA

notes that while a value of zero may be appropriate for a fractured medium, it may not 

be appropriate for a consolidated and healed DRZ, such as is conceptually assumed 

for the DRZ_PCS during T3. In addition, SAT_RGAS is treated as a constant for the 

DRZ_PCS while it was sampled over a range from zero to 0.4 for the ROM salt 

material. The lack of consistent treatment and the appropriateness of a zero value 

should be justified. EPA accepts the value of DRZ_PCS:SAT_RGAS used in PCS2012 despite a lack of justification, because it was also used in PABC-2009 and 

facilitates comparison of results. Also see text discussion of two-phase flow 

parameters.

References for Supporting Documents:

ERMS 232288: Vaughn 1996a

ERMS 232910: SNL 1997

ERMS 235271: Vaughn 1996b

ERMS 236051: Vaughn 1996c

ERMS 238568: Tierney and Vaughn 1996

ERMS 519513: Wall 2001

ERMS 520524: Stein 2002a

ERMS 520612: Stein 2002b

ERMS 542894: Vugrin et al. 2006

ERMS 542946: Vugrin 2006

ERMS 543322: PDE 2006a

ERMS 543328: PDE 2006c

ERMS 545496: Vugrin and Nemer 2007

ERMS 545755: Ismail 2007

ERMS 554623: Camphouse 2010

ERMS 557396: Camphouse et al. 2012a

ERMS 557721: Camphouse 2012

ERMS 557865: Patterson 2012

ERMS 557949: PDE 2012a

ERMS 557951: PDE 2012b
27

4.3.1 Use of Default Values

As previously noted, distributed parameters are now assigned a default value in the PAPDB for 

use when the distribution is not to be sampled (Kirchner 2011). Seven parameters were sampled 

for the ROM salt materials and three parameters were sampled for the PCS DRZ materials. The 

sampled parameters are shown in Table 1. When a sampled parameter value is applied without 

change for all three time periods in the PCS-2012 analysis, the sampling occurs during the first 

time period where the parameter is used. The default value, shown in Table 1, is retrieved from 

the database for subsequent time periods and is later set equal to the original sampled value in 

the BRAGFLO ALGEBRA1 file. This same process is used for directional permeabilities in 

isotropic media. The X-direction permeability PRMX_LOG is sampled, default values are 

retrieved from the database for PRMY_LOG and PRMZ_LOG, and are later set equal to the 

PRMX_LOG value in the BRAGFLO ALGEBRA1 file. 

The foregoing sampling process is applied to four of the six sampled ROM salt properties 

(PORE_DIS; POR2PERM; SAT_RBRN, and SAT_RGAS) and is also applied to all sampled 

PCS DRZ properties (PRMX, Y, Z_LOG; POROSITY; and RELP_MOD). The ROM salt

property POR2PERM applies only to time periods T2 and T3. The ROM salt property 

POROSITY is separately sampled from uniform distributions for the three time periods T1, T2, 

and T3. The initial brine saturation of the ROM salt, SAT_IBRN, is sampled from a uniform 

distribution. The sampled value is applied at time zero and replaces the brine saturation 

calculated during the 5 year preclosure time period. The ROM salt permeability is directly 

sampled for T1. For T2 and T3, default values are taken from the database and the permeabilities 

used in the PCS-2012 analysis are calculated as a function of the randomly selected values of 

POR2PERM and POROSITY. This process is further explained below.

4.3.2 ROM Salt Porosity and Permeability Values

The porosity of the ROM salt is sampled from a uniform distribution for time period T1. For 

time period T2, the ROM salt porosity is sampled from a different uniform distribution and is 

compared to the porosity value sampled for T1. If the T2 value is greater than the T1 value, a 

new T2 value is calculated that is less than or equal to the T1 value. Similarly, for time period 

T3, the ROM salt porosity is sampled from a third uniform distribution and is compared to the 

porosity value determined for T2. If the T3 value is greater than the T2 value, a new T3 value is 

calculated that is less than or equal to the T2 value. This approach is appropriate because the 

porosity of the ROM salt should be monotonically decreasing during creep closure. The porosity 

ranges for the three time periods are shown in Table 1.

The log permeability of the ROM salt is sampled from a uniform distribution for time period T1, 

independent of the sampled porosity value for T1. The log permeability for the ROM salt is then 

determined for time period T2 as a function of the T2 porosity and the sampled value of a 

parameter called PCS_T2:POR2PERM that is used to correlate permeability with porosity. SNL 

developed a correlation between porosity (expressed as fractional salt density) and log 

permeability based on laboratory brine permeability studies by Brodsky (1994). Development of 

this correlation is described by Camphouse et al. (2012a). This correlation showed that the

permeability of moist, crushed salt consolidating under an external applied stress tends to 
28

decrease as the porosity decreases. Such a correlation is logical and would be generally expected. 

Consolidation data for moist crushed salt is also appropriate, as compared with data for dry 

crushed salt, because moist conditions are expected in the post-closure repository. A least 

squares linear fit to the data served to identify the expected value of log permeability as a 

function of porosity, and at a given porosity the distribution of test results around this expected 

value was shown to be reasonably well approximated by a normal distribution. This normal 

distribution was standardized by taking the expected value as the mean, assigning the mean a 

default value of zero, and sampling over two standard deviations from the mean. The sampled 

value of PCS_T2:POR2PERM is the deviation from the mean of this normal distribution of log 

permeability values. 

Knowing the value of PCS_T2:POROSITY, an algorithm in the BRAGFLO ALGEBRA1 file 

calculates the actual value of the mean permeability corresponding to that porosity and replaces 

the default value of zero with the actual value. Knowing the value PCS_T2:POR2PERM, the 

algorithm also uses the deviation from that mean to calculate the value of PCS_T2:PRMX_LOG. 

Because the ROM salt is assumed to be isotropic, this same log permeability is assigned to 

PCS_T2:PRMY_LOG and PCS_T2:PRMZ_LOG. The PAPDB contains only constant default 

values of PCS_T2:PRMX_LOG, PCS_T2:PRMY_LOG, and PCS_T2:PRMZ_LOG as 

placeholders. These default values are the means of the overall ranges of log permeability values 

corresponding to the range of porosities applicable to time period T2 and are the same for all 

three directional permeabilities. These default values are replaced by the calculated values once 

the actual log permeabilities are determined. 

A separate calculation is then made to compare the T2 permeability with the T1 permeability. If 

the T2 permeability is greater than the sampled T1 permeability, the T2 permeability is set equal 

to the T1 permeability. This approach is appropriate, because the permeability of the ROM salt

should be monotonically decreasing during creep closure.

A similar process is used to determine the T3 permeability, however for this time period, the 

value of POR2PERM is assumed to be the same as for time period T2. This is accomplished by 

retrieving a constant default value of 0.0 from the PAPDB for parameter PCS_T3:POR2PERM

and replacing that default value with the sampled value of PCS_T2:POR2PERM in the 

BRAGFLO ALGEBRA1 file. This approach maintains the same deviation from the mean for the 

permeability distribution during time periods T2 and T3 and is appropriate, because if an above 

normal permeability is sampled for T2, for example, it is reasonable that the permeability for T3 

would also likely be above normal. 

Knowing the value of PCS_T3:POROSITY, an algorithm in the BRAGFLO ALGEBRA1 file 

calculates the actual value of the mean and replaces the default mean value of zero with the 

actual value. Knowing that the value of PCS_T3:POR2PERM is the same as the value of 

PCS_T2:POR2PERM, this algorithm also uses the deviation from that mean to calculate the

value of PCS_T3:PRMX_LOG. Because the ROM salt is assumed to be isotropic, this same log 

permeability is assigned to the Y- and Z-directional permeabilities during time period T3. Again, 

the PAPDB contains only constant default values of PCS_T3:PRMX_LOG, 

PCS_T3:PRMY_LOG, and PCS_T3:PRMZ_LOG as placeholders. These default values are the 

means of the overall range of log permeability values corresponding to the range of porosities 
29

applicable to time period T3 and are replaced by the calculated values once the actual log 

permeabilities are determined. The T3 permeabilities calculated in this manner will generally be 

different from the T2 permeabilities because of the differences in porosity values.

A separate calculation is then made to compare the T3 permeability with the T2 permeability. If 

the T3 permeability is greater than the T2 permeability, the T3 permeability is set equal to the T2

permeability. This approach is appropriate, because the permeability of the ROM salt should be 

monotonically decreasing during creep closure.

The ROM salt log permeability used in the PCS-2012 PA for time period T1 ranges over nine 

orders of magnitude, from a low of -21 log(m2) (1×10-21m

2

) to a high of -12 log(m2) (1×10-12

m

2

). The default value of -16.5 for PCS_T1:PRMY_LOG, and PCS_T1:PRMZ_LOG is the 

mean of this range. This range was developed by SNL based on laboratory data for consolidated 

crushed salt at or near the minimum (0.066) and maximum (0.187) porosities in the range 

sampled for time period T1. 

The ROM salt log permeability for time period T2 ranges from -20.8 log(m2) (1.44×10-21m

2

) to 

-16.3 log(m2) (4.55×10-17 m

2

), however only the mean constant default value of -18.6 log(m2) is 

entered into the PAPDB for all three T2 directional permeabilities. The ROM salt log 

permeability for time period T3 ranges from -21.4 log(m2) (4.46×10-22m

2

) to -16.8 log(m2) 

(1.47×10-17 m

2

), however only the mean constant default value of -19.1 log(m2) is entered into 

the PAPDB for all three T3 directional permeabilities. These permeability ranges are not 

provided in the PAPDB, but are documented in Camphouse et al. (2012a).

Following completion of the PCS-2012 PA calculations, an error in calculating the permeability 

of the ROM salt materials for time periods T2 and T3 was discovered in the BRAGFLO 

ALGEBRA1 file. The permeability is calculated using the equation

k = 10-21.187(1 – Φ) + 1.5353 + α

where k is the calculated permeability, Φ is the sampled porosity value, and α is the sampled

POR2PERM value from a normal distribution with a mean of 0, a standard deviation of 0.86, and 

truncated at ±2 standard deviations. Upon closer inspection, The Agency found that the leadingterm constant of -21.187 in this equation was incorrectly transcribed to the ALGEBRA1 input 

file as

-21.87 for both materials PCS_T2 and PCS_T3. This error led to calculated permeabilities for 

materials PCS_T2 and PCS_T3 that were lower than the minimum values listed above for some 

vectors. However, as described in Camphouse et al. (2012b), this transcription error was found to 

have a negligible impact on the PCS-2012 PA results. SNL reran Replicate 1 of the PCS-2012 

PA with the corrected equation and the resulting releases were virtually identical with those of 

the original analysis.

As previously described, the original range of T1 log permeabilities was from -18.7 to 

-12.0 log(m2), and the low end was later extended from -18.7 to -21.0 log(m2) based on the 

minimum value from Test 3 of Case et al. (1987), as corrected for the Klinkenberg effect 

(Patterson 2012). Case et al.’s Test 3 was for moist WIPP salt with 20 mm maximum grain size. 
30

These same test results were considered by Camphouse et al. (2012a), but were not used when 

developing the original T1 permeability range “...because the maximum grain size for Test 3, 20 

mm, is somewhat smaller than the measured maximum grain size for WIPP salt, 38 mm.” 

(Camphouse et al. 2012a). Generally, permeability would be expected to drop more rapidly when 

consolidating a finer-grained material than when consolidating a coarser-grained material. 

However, Patterson notes a disagreement on the magnitude of this effect in laboratory test results 

and concludes that, “The impact of grain size on permeability measurements for moistened cores 

of crushed salt is ambiguous at this time” (Patterson 2012). 

In light of the apparent disagreement within DOE over whether to include the Case et al. Test 3 

results in the range of ROM salt permeabilities for T1, the Agency performed an independent 

evaluation of the appropriateness of the T1 permeability range for the purpose of the PCS-2012 

PA. The Agency observes that the range of permeabilities used in the PCS-2012 PA for time 

period T1 is larger than the ranges for the subsequent time periods, suggesting a greater 

uncertainty during T1. This uncertainty arises in part from uncertainty in the rate at which the 

ROM salt is compressed during creep closure, and also in part from uncertainty in the method 

that will be used by DOE to emplace the ROM salt. The Agency also notes that the minimum 

permeability of -21.0 log(m2) during T1 is less than the minimum permeability during T2 for the 

entire range of T2 porosities, and is also less than the minimum permeability during T3 for most 

T3 porosities. These comparisons indicate an inconsistency with the aforementioned conceptual 

model of monotonically decreasing permeability over time, as well as an inconsistency between 

the permeability data sets used by DOE. 

The adjustments SNL has made to the sampled/calculated values of porosity and permeability to 

assure physically reasonable monotonic decreases in the values of these parameters with time has 

also contributed to some permeabilities falling below the originally agreed-upon two standard 

deviation range for T2 and T3. Although the Agency believes that the minimum ROM salt

permeability of -21.0 log(m2) during time period T1 may be unrealistically low for coarse WIPP 

ROM salt in an initial time period of 100 years, the Agency understands that the T2 and T3 data 

sets from Brodsky (1994) are relatively sparse, and that a high degree of uncertainty is associated 

with the consolidation of an ROM salt panel closure during T1. The Agency accepts the use of 

the applied permeability range for T1 because of the uncertainty involved, and because a log 

permeability of -21.0 log(m2) is several orders of magnitude higher than the lowest permeability 

of -24.0 log(m2) used for intact WIPP halite, indicating that complete healing of the ROM salt 

has not yet occurred. However, if the Agency approves DOE’s proposal to modify the PCS 

design and if the uncertainty in the T1 permeability range is reduced, for example when the 

initial conditions of the ROM salt are better understood once the method of salt emplacement is 

determined by DOE or if additional relevant data become available, the Agency may re-evaluate 

the appropriateness of the T1 ROM salt permeability range for use in future PAs.

4.3.3 PCS DRZ Porosity and Permeability Values

As indicated in Tables 1 and 2, the porosity values for the DRZ above and below the ROM salt 

were not adequately justified and were modeled as unchanging during all three time periods. The 

permeability data were better supported and did generally reflect a decrease over time, as would 

be expected with a consolidating material. However, the permeability ranges for material DRZ_1
31

(early time) overlap with those for material DRZ_PCS (late time), which may result in an 

unrealistic permeability increase in late time because the distributions are sampled 

independently. Additionally, the PCS DRZ permeability is independent of the ROM salt 

permeability, even though the conceptual model described by Camphouse et al. (2012a) states, 

“As ROM salt reaches higher fractional densities during consolidation, back stress will be 

imposed on the surrounding rock mass leading to eventual healing of the disturbed rock zone 

(DRZ).” The Agency agrees that healing of the PCS DRZ cannot occur until sufficient back 

stress is generated by the ROM salt and such back stress cannot be generated until the ROM salt 

is sufficiently consolidated to significantly reduce its porosity and permeability. It is apparent 

that the decrease in permeability of the PCS DRZ is correlated with the decrease in permeability 

of the ROM salt. Although the Agency agreed with the PCS DRZ values used in PCS-2012 to 

maintain consistency with PABC-2009 and simplify comparison of results, the appropriateness 

of conditioning for monotonic decreases in porosity and permeability over time, and for 

correlating decreases in PCS DRZ porosity and permeability with decreases in ROM salt 

porosity and permeability, may be evaluated by the Agency for the 2014 recertification PA.

4.3.4 Two-Phase Flow Parameters

Relative permeability Model 4 is a Brooks-Corey model that was modified by SNL to use a 

residual gas saturation in calculating the effective saturation for the relative permeability of the 

non-wetting (gas) phase. Model 4 was used to model two-phase flow in the PCS-2012 PA for 

both the ROM salt and the surrounding PCS DRZ. Inputs for this model specific to two-phase 

flow include a capillary pressure model CAP_MOD, a pore distribution PORE_DIS, an initial 

brine saturation SAT_IBRN, a residual brine saturation SAT_RBRN, and a residual gas 

saturation SAT_RGAS. Capillary pressure Models 1 and 2 are generally used in WIPP PA. 

Model 1 is similar to Model 2, except that Model 2 invokes a maximum value for the capillary 

pressure, while Model 1 has no maximum and is typically used when the threshold capillary 

pressure is set to zero, which deactivates the model. Inputs for the capillary pressure models 

include a maximum allowable capillary pressure PC_MAX (for Model 2) and a threshold 

capillary pressure Pt. If the threshold capillary pressure is set to zero, the material is modeled in 

BRAGFLO as having no (zero) capillary pressure. A minimum allowable capillary pressure 

PO_MIN must also be specified in the database, but is only used in capillary pressure Model 3, 

which was not used in either PCS-2012 or PABC-2009.

Threshold capillary pressure is the pressure required for a gas to overcome capillary forces and 

enter a brine-saturated salt. Threshold capillary pressure for the Brooks-Corey model is 

calculated as 

Pt = a k–b

where a is called the linear parameter, designated in WIPP PA as the property PCT_A, k is the 

permeability of the material in the X-direction, and b is the exponential parameter, designated in 

WIPP PA as the property PCT_EXP. Both a and b are constants in WIPP PA. Inputs for the 

threshold capillary pressure model are, therefore, PCT_A, PCT_EXP, the permeability k, and a 

flag called KPT that determines whether k is constant (KPT = 0.0) or whether k changes with 

time (KPT = 1.0) during the analysis. According to Chris Camphouse (SNL’s BRAGFLO 
32

administrator), k is automatically reset to the current X-direction permeability each time the 

material changes. Therefore, even if KPT is set to zero, the threshold capillary pressure is 

recalculated for the ROM salt for each time period T1, T2, and T3, because PCS_T1, PCS_T2, 

and PCS_T3 each represent a different material in BRAGFLO.

Two-phase flow parameters for unconsolidated salt were first developed in WIPP PA for 

modeling the DRZ around the waste panels and for modeling the salt component of the original 

shaft seal. The waste panel DRZ was considered to retain open fractures and relatively high 

permeabilities (compared to intact halite) for the entire regulatory time frame because of the 

disruptive effects of gas pressurization from waste decomposition. The salt component of the 

original shaft seal was to be emplaced as a porous material using ROM WIPP salt, also with a 

relatively high permeability. The open fractures and pores of the waste panel DRZ were 

considered to result in an essentially zero threshold capillary pressure, a zero residual brine 

saturation, and a zero residual gas saturation. Capillary pressures are not modeled in a material if 

the threshold capillary pressure is zero. In addition, KPT was set to zero, because permeabilities 

remained constant during a given realization.

Zero values continued to be assigned to these DRZ parameters until the DOE proposed a 

modified panel closure design that used ROM salt, whose consolidation was to be specifically 

modeled over three time periods in the PCS-2012 PA. The agreed upon parameterization for that 

PA included a nonzero threshold capillary pressure for the ROM salt, a residual brine saturation 

that was sampled over a range from 0.0 to 0.6, and a residual gas saturation that was sampled 

over a range from 0.0 to 0.4. The effect of nonzero values for these parameters is to add 

restrictions to the flow of brine and gas in the salt. Low values approaching zero for threshold 

capillary pressure, residual brine saturation, and residual gas saturation may be appropriate for 

materials that have open fractures, but nonzero values would be expected for consolidated 

materials. Capillary pressure Model 2 is typically used when the threshold capillary pressure is 

nonzero, and that model was specified in the agreed-upon parameterization. Zero values for these 

parameters were used for the PCS DRZ to maintain consistency with the baseline PABC-2009 

and simplify comparison of the effects of different panel closure designs.

As previously stated, capillary pressure Model 1 is typically used in WIPP PA when the 

threshold capillary pressure is zero. When performing the PCS-2012 PA, DOE found that a 

nonzero threshold capillary pressure for the ROM salt caused numerical difficulties in 

BRAGFLO and resolved this problem by setting the threshold capillary pressure for the ROM 

salt to zero. Because this change was not consistent with the parameterization that the Agency 

had previously agreed upon and the effect of a nonzero threshold capillary pressure could not be 

determined from the PCS-2012 results, the Agency requested DOE to correct the numerical 

difficulties in BRAGFLO and rerun the PCS-2012 PA with nonzero threshold capillary pressures 

in the ROM salt. 

SNL found that the aforementioned numerical difficulties arose when the threshold capillary 

pressure was nonzero and the initial brine saturation was less than the residual brine saturation. 

In capillary pressure Model 2, BRAGFLO computes the brine saturation at which the capillary 

pressure equals the maximum allowable capillary pressure, PCMAX. Because capillary pressure 

increases as brine saturation decreases, this calculated value is the minimum allowable brine 
33

saturation for the particular material. If the initial brine saturation is less than this minimum 

value, the capillary pressure is set to the PCMAX value of 1 × 108Pa (Nemer 2007b). In 

previous analyses, the initial brine saturation was set to 1.0 (a fully saturated condition) at time -

5 years for the DRZ and intact halite in the vicinity of a waste panel, and at time zero, the brine 

saturation was the saturation calculated by BRAGFLO after 5 years of drainage into the waste 

panel. However, for the ROM salt, the initial brine saturation SAT_IBRN was reset to a much 

drier condition at time zero that was representative of the expected range of brine saturations for 

granular ROM salt. Because this initial saturation was less than the minimum value, the capillary 

pressure was increased to 1 × 108Pa at time zero. Because gas pressure equals brine pressure 

plus capillary pressure, BRAGFLO also increased gas pressure at time zero by 1 × 108Pa over 

the brine pressure to maintain equilibrium conditions. Because the gas pressure in adjacent 

materials at time zero was still low, this sudden increase created an unrealistically high gas 

pressure gradient that resulted in numerical difficulties in BRAGFLO. Numerical difficulties can 

also arise as the brine saturation drops and approaches the residual brine saturation because 

capillary pressures are increasing rapidly at these low saturations. In addition to the lack of a 

physical reason why the gas pressure in the repository should suddenly increase to a high value 

at time zero, as discussed below, brine saturations below the residual brine saturation represent a 

non-physical condition in BRAGFLO.

In previous analyses, the aforementioned numerical difficulties in BRAGFLO were resolved by 

reverting to capillary pressure Model 1 and setting the threshold capillary pressure to zero. This 

set the capillary pressure to zero and made the gas pressure equal to the brine pressure, thereby 

eliminating large gas pressure gradients between adjacent materials. A nonzero threshold 

capillary pressure can be specified in Model 1, but unlike Model 2, no maximum value for 

capillary pressure is provided in Model 1. Because there is no maximum capillary pressure in 

Model 1, if the brine saturation is below the residual brine saturation, the capillary pressure is 

arbitrarily set to zero (Nemer 2007b). This default, coupled with a zero capillary pressure for 

higher brine saturations, set capillary pressure in Model 1 to zero for any brine saturation. 

Eliminating capillary pressure altogether eliminated large gas pressure gradients and allowed 

BRAGFLO to converge more readily.

The initial brine saturation for the ROM salt was determined to range from 0.04 to 0.16, 

assuming a granular material that had dried and was partially rewetted, whereas the residual 

brine saturation was sampled over a range from 0.0 to 0.6, resulting in many vectors with 

sampled residual brine saturations greater than the initial brine saturations. Although the range of 

initial brine saturations is physically reasonable, they can only be reached by assuming an 

evaporative or chemically based moisture removal process that is not modeled in BRAGFLO. 

Under the humid conditions modeled in BRAGFLO, such a drying process could not happen, 

because it would require brine flow in salt to occur below the lower limit that such flow could 

occur, as defined by the residual brine saturation. This numerical problem can be resolved by 

setting the initial brine saturation above the residual brine saturation. It was temporarily resolved 

by SNL by increasing the initial brine saturation of the ROM salt to 1.0. The Agency considers 

the assumption of higher brine saturations to be appropriate, because humid conditions are 

expected to develop in the repository soon after closure.
34

SNL reran the corrected BRAGFLO code with an initial brine saturation of the ROM salt at time 

zero reset to 1.0 and nonzero threshold capillary pressures in the ROM salt for all three time 

periods. The initial brine saturation in the PCS DRZ did not need to be changed, because it was 

set to 1.0 at time -5 years and not reset at time zero. The results showed that including threshold 

capillary pressures in the ROM salt made no significant difference in the mean repository 

releases. Because SNL’s BRAGFLO runs were not reviewed for quality assurance purposes, the 

WIPP PA codes were reviewed and rerun by the Agency with the same results. The Agency 

therefore concludes that DOE’s deviation from the agreed-upon parameterization in PCS-2012 is 

acceptable. 

As described above, the Agency accepted retention in the PCS-2012 PA of several parameter 

values from the PABC-2009 PA to simplify comparison of results by focusing only on parameter 

value changes that were potentially significant and resulted directly from the proposed changes 

in PCS design. However, when agreeing with the parameter values for the PCS-2012 PA in June 

2012, the Agency noted that although the multi-phase flow and other parameters in BRAGFLO 

could remain as they have been in past PAs, they may be re-evaluated for appropriateness in the 

2014 recertification PA.

4.4 REVIEW OF PAPDB DATABASE-TO-CODE INTERFACE FOR PCS-2012

Accurate access by the WIPP PA codes of PAPDB parameter values was evaluated by visually 

comparing code input files with PAPDB database values. The PA code input files were accessed 

by SNL staff member Jennifer Long in the SNL Carlsbad office. The input files were observed 

and compared with PAPDB values by the Agency review team. This review was conducted for 

all parameters used in PCS-2012 that have changed since CRA-2009. The results of this review 

are shown in Table 3.

Table 3 presents the parameter name (material and property), the code that used the parameter, 

the names of the input file and library that were accessed, the parameter value in PAPDB, the 

parameter value returned from the PAPDB, and comments providing additional details. In every 

case, the code using the parameter was BRAGFLO. BRAGFLO Version 6.0 (Nemer 2007a) was 

used in both PCS-2012 and in CRA-2009. For all constant parameters, the value returned was the 

same as the PAPDB value. For all distributed parameters, the value returned was within the 

range of the parameter distribution. For distributed parameters, two or more values were 

generally returned, representing samples for specific replicates and vectors randomly selected by 

the Agency reviewer. In all but one case, the correct values were returned.

The single exception was the sampled value for DRZ_1:RELP_MOD. This parameter identifies 

the relative permeability model to be used for material DRZ_1. This parameter is entered into the 

PAPDB as a sampled value from a Delta function with a probability of 0.33 for a value of 1 

(which selects relative permeability Model 1, a modified van Genuchten-Parker model) and a 

probability of 0.67 for a value of 4 (which selects relative permeability Model 4, a modified 

Brooks-Corey model). However, three different vectors were checked from three replicates, and 

in each case a value of 4 was returned. The sampled results were further checked and a value of 4 

was returned for every vector in every replicate. Although this indicates a problem with the 

PRELHS sampling algorithm, the Agency concludes that it has no impact on the PCS-2012 
35

results, because relative permeability Model 4 is the desired model for the modified BrooksCorey model used in PCS-2012 and PABC-2009. This problem did not exist for the parameter 

DRZ_PCS:RELP_MOD, because the default value of zero was returned and later set equal to the 

sampled value for DRZ_1:RELP_MOD in the BRAGFLO ALGEBRA1 file. This problem also

did not exist for the ROM salt, because the value of RELP_MOD for that material is entered in 

the PAPDB as a constant equal to 4 for all three time periods. The Agency informed Chris 

Camphouse (SNL) of this error. He confirmed the error and said it would also have been present 

in PABC-2009 and will be corrected by changing this parameter to a constant value. 

The methodology used to establish a value for DRZ_1:POROSITY is complex and warrants a 

brief explanation. The porosity of the DRZ around the PCS is the same as the porosity of the 

DRZ around a waste panel. The value of this parameter is derived from a sampled porosity value 

for intact halite which, once determined, remains unchanged throughout the regulatory time 

frame. Most such parameters are sampled for the first time period (usually the zero to 200-year 

time period of DRZ_1 for the DRZ PCS) and a default value is taken from the database for later 

time periods (in this case, the 200 to 10,000-year time period for material DRZ_PCS) that is 

subsequently set equal to the sampled value for the earlier time period in the BRAGFLO 

ALGEBRA1 file. However, for DRZ_1:POROSITY, the default value rather than a sampled 

value is taken from the database and is then set equal to the value for parameter 

DRZ_0:POROSITY in the BRAGFLO ALGEBRA1 file. DRZ_0:POROSITY is the porosity 

assigned to the DRZ for the time period -5 years to time zero. This time period is used to 

establish initial conditions in the DRZ at time zero for BRAGFLO parameters, such as initial 

brine saturation. The value of DRZ_0:POROSITY is equal to the sampled porosity value for 

intact halite, S_HALITE:POROSITY, plus a constant value of 0.0029 (parameter 

DRZ_0:ADDPOR). This correlation assures that the porosity of the DRZ is always greater than 

the porosity of intact halite. Although the distributions for DRZ_0:POROSITY, 

DRZ_1:POROSITY, DRZ PCS:POROSITY, and S_HALITE:POROSITY are correct in the 

PAPDB, only the distribution for S_HALITE:POROSITY is actually sampled. This parameter

was handled the same way in the PCS-2012 PA as it was in the PABC-2009.
36

Table 3. Database-Code Interface Test Results for Parameters Used in the PCS-2012 PA that have 

Changed since PABC-2009

Material Name Property Name Code File Name Library PAPDB 

Value

Value 

Returned Comments

PCS_T1 CAP_MOD BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1 1 The correct value was returned.

PCS_T2 CAP_MOD BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1 1 The correct value was returned.

PCS_T3 CAP_MOD BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1 1 The correct value was returned.

PCS_T1 COMP_RCK BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 8.0E-11 8.0E-11 The correct value was returned.

PCS_T2 COMP_RCK BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 8.0E-11 8.0E-11 The correct value was returned.

PCS_T3 COMP_RCK BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 8.0E-11 8.0E-11 The correct value was returned.

PCS_T1 KPT BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

PCS_T2 KPT BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

PCS_T3 KPT BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

PCS_T1 PC-MAX BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1.0E08 1.0E08 The correct value was returned.

PCS_T2 PC-MAX BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1.0E08 1.0E08 The correct value was returned.

PCS_T3 PC-MAX BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1.0E08 1.0E08 The correct value was returned.

PCS_T1 PCT_A BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

PCS_T2 PCT_A BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

PCS_T3 PCT_A BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

PCS_T1 PCT_EXP BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

PCS_T2 PCT_EXP BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

PCS_T3 PCT_EXP BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

PCS_T1 PO_MIN BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1.01325E05 1.01325E05 The correct value was returned.

PCS_T2 PO_MIN BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1.01325E05 1.01325E05 The correct value was returned.

PCS_T3 PO_MIN BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1.01325E05 1.01325E05 The correct value was returned.

PCS_T1 PORE_DIS BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.11 to 8.1 0.5301

Value from R2 V31. Sampled value 

correctly lies within the sampled range 

of 0.11 to 8.1.

PCS_T1 PORE_DIS BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 0.11 to 8.1 7.108

Value from R1 V57. Sampled value 

correctly lies within the sampled range 

of 0.11 to 8.1.

PCS_T2 PORE_DIS BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.11 to 8.1 0.940 Value from R2 V31. The default value 

was correctly returned.

PCS_T2 PORE_DIS BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 0.11 to 8.1 0.940 Value from R1 V57. The default value 

was correctly returned.
37

Table 3. Database-Code Interface Test Results for Parameters Used in the PCS-2012 PA that have 

Changed since PABC-2009

Material Name Property Name Code File Name Library PAPDB 

Value

Value 

Returned Comments

PCS_T2 PORE_DIS BRAGFLO LHS3_BF_AP161_R3_V042.CDB LIBAP161_BF 0.11 to 8.1 0.940 Value from R3 V42. The default value 

was correctly returned.

PCS_T3 PORE_DIS BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.11 to 8.1 0.940 Value from R2 V31. The default value 

was correctly returned.

PCS_T3 PORE_DIS BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 0.11 to 8.1 0.940 Value from R1 V57. The default value 

was correctly returned.

PCS_T3 PORE_DIS BRAGFLO LHS3_BF_AP161_R3_V042.CDB LIBAP161_BF 0.11 to 8.1 0.940 Value from R3 V42. The default value 

was correctly returned.

PCS_T1 POROSITY BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.066 to 

0.187 0.09049

Value from R2 V31. Sampled value 

correctly lies within the sampled range 

of 0.066 to 0.187.

PCS_T1 POROSITY BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 0.066 to 

0.187 0.07102

Value from R1 V57. Sampled value 

correctly lies within the sampled range 

of 0.066 to 0.187.

PCS_T2 POROSITY BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.025 to 

0.075 0.06855

Value from R2 V31. Sampled value 

correctly lies within the sampled range 

of 0.025 to 0.075.

PCS_T2 POROSITY BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 0.025 to 

0.075 0.02965

Value from R1 V57. Sampled value 

correctly lies within the sampled range 

of 0.025 to 0.075.

PCS_T2 POROSITY BRAGFLO LHS3_BF_AP161_R3_V042.CDB LIBAP161_BF 0.025 to 

0.075 0.02683

Value from R3 V42. Sampled value 

correctly lies within the sampled range 

of 0.025 to 0.075.

PCS_T3 POROSITY BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.001 to 

0.0519 0.03087

Value from R2 V31. Sampled value 

correctly lies within the sampled range 

of 0.001 to 0.0519.

PCS_T3 POROSITY BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 0.001 to 

0.0519 0.01855

Value from R1 V57. Sampled value 

correctly lies within the sampled range 

of 0.001 to 0.0519.

PCS_T3 POROSITY BRAGFLO LHS3_BF_AP161_R3_V042.CDB LIBAP161_BF 0.001 to 

0.0519 0.01705

Value from R3 V42. Sampled value 

correctly lies within the sampled range 

of 0.001 to 0.0519.

PCS_T1 PRMX_LOG BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -21 to -12 -14.24

Value from R2 V31. Sampled value 

correctly lies within the sampled range 

of -21 to -12.

PCS_T1 PRMX_LOG BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -21 to -12 -18.04

Value from R1 V57. Sampled value 

correctly lies within the sampled range 

of -21 to -12.

PCS_T1 PRMY_LOG BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -16.5 -16.5 Value from R2 V31. The default value 

was correctly returned.

PCS_T1 PRMY_LOG BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -16.5 -16.5 Value from R1 V57. The default value 

was correctly returned.

PCS_T1 PRMZ_LOG BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -16.5 -16.5 Value from R2 V31. The default value 

was correctly returned.
38

Table 3. Database-Code Interface Test Results for Parameters Used in the PCS-2012 PA that have 

Changed since PABC-2009

Material Name Property Name Code File Name Library PAPDB 

Value

Value 

Returned Comments

PCS_T1 PRMZ_LOG BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -16.5 -16.5 Value from R1 V57. The default value 

was correctly returned.

PCS_T2 POR2PERM BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -1.72 to 

+1.72 0.8755

Value from R2 V31. Sampled value 

correctly lies within the sampled range 

of -1.72 to +1.72.

PCS_T2 POR2PERM BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -1.72 to 

+1.72 -1.092

Value from R1 V57. Sampled value 

correctly lies within the sampled range 

of -1.72 to +1.72.

PCS_T2 PRMX_LOG BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -18.6 -18.6

Value from R2 V31. The default value 

was correctly returned. See text 

discussion.

PCS_T2 PRMX_LOG BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -18.6 -18.6 Value from R1 V57. The default value 

was correctly returned.

PCS_T2 PRMY_LOG BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -18.6 -18.6 Value from R2 V31. The default value 

was correctly returned.

PCS_T2 PRMY_LOG BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -18.6 -18.6 Value from R1 V57. The default value 

was correctly returned.

PCS_T2 PRMZ_LOG BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -18.6 -18.6 Value from R2 V31. The default value 

was correctly returned.

PCS_T2 PRMZ_LOG BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -18.6 -18.6 Value from R1 V57. The default value 

was correctly returned.

PCS_T3 POR2PERM BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -1.72 to 

+1.72 0

Value from R2 V31. The default value 

was correctly returned. See text 

discussion.

PCS_T3 POR2PERM BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -1.72 to 

+1.72 0

Value from R1 V57. The default value 

was correctly returned.

PCS_T3 PRMX_LOG BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -19.1 -19.1

Value from R2 V31. The default value 

was correctly returned. See text 

discussion.

PCS_T3 PRMX_LOG BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -19.1 -19.1 Value from R1 V57. The default value 

was correctly returned.

PCS_T3 PRMY_LOG BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -19.1 -19.1 Value from R2 V31. The default value 

was correctly returned.

PCS_T3 PRMY_LOG BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -19.1 -19.1 Value from R1 V57. The default value 

was correctly returned.

PCS_T3 PRMZ_LOG BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -19.1 -19.1 Value from R2 V31. The default value 

was correctly returned.

PCS_T3 PRMZ_LOG BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -19.1 -19.1 Value from R1 V57. The default value 

was correctly returned.

PCS_T1 RELP_MOD BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 4 4 The correct value was returned.

PCS_T2 RELP_MOD BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 4 4 The correct value was returned.

PCS_T3 RELP_MOD BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 4 4 The correct value was returned.
39

Table 3. Database-Code Interface Test Results for Parameters Used in the PCS-2012 PA that have 

Changed since PABC-2009

Material Name Property Name Code File Name Library PAPDB 

Value

Value 

Returned Comments

PCS_T1 SAT_IBRN BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.04 to 0.16 0.1335

Value from R2 V31. Sampled value 

correctly lies within the sampled range 

of 0.04 to 0.16.

PCS_T1 SAT_IBRN BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 0.04 to 0.16 0.1337

Value from R1 V57. Sampled value 

correctly lies within the sampled range 

of 0.04 to 0.16.

PCS_T1 SAT_RBRN BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 to 0.6 0.1561

Value from R2 V31. Sampled value 

correctly lies within the sampled range 

of 0.0 to 0.6.

PCS_T1 SAT_RBRN BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 0.0 to 0.6 0.5511

Value from R1 V57. Sampled value 

correctly lies within the sampled range 

of 0.0 to 0.6.

PCS_T2 SAT_RBRN BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 to 0.6 0.2 Value from R2 V31. The default value 

was correctly returned.

PCS_T2 SAT_RBRN BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 0.0 to 0.6 0.2 Value from R1 V57. The default value 

was correctly returned.

PCS_T2 SAT_RBRN BRAGFLO LHS3_BF_AP161_R3_V042.CDB LIBAP161_BF 0.0 to 0.6 0.2 Value from R3 V42. The default value 

was correctly returned.

PCS_T3 SAT_RBRN BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 to 0.6 0.2 Value from R2 V31. The default value 

was correctly returned.

PCS_T3 SAT_RBRN BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 0.0 to 0.6 0.2 Value from R1 V57. The default value 

was correctly returned.

PCS_T3 SAT_RBRN BRAGFLO LHS3_BF_AP161_R3_V042.CDB LIBAP161_BF 0.0 to 0.6 0.2 Value from R3 V42. The default value 

was correctly returned.

PCS_T1 SAT_RGAS BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 to 0.4 0.105

Value from R2 V31. Sampled value 

correctly lies within the sampled range 

of 0.0 to 0.4.

PCS_T1 SAT_RGAS BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 0.0 to 0.4 0.07844

Value from R1 V57. Sampled value 

correctly lies within the sampled range 

of 0.0 to 0.4.

PCS_T2 SAT_RGAS BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 to 0.4 0.2 Value from R2 V31. The default value 

was correctly returned.

PCS_T2 SAT_RGAS BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 0.0 to 0.4 0.2 Value from R1 V57. The default value 

was correctly returned.

PCS_T2 SAT_RGAS BRAGFLO LHS3_BF_AP161_R3_V042.CDB LIBAP161_BF 0.0 to 0.4 0.2 Value from R3 V42. The default value 

was correctly returned.

PCS_T3 SAT_RGAS BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 to 0.4 0.2 Value from R2 V31. The default value 

was correctly returned.

PCS_T3 SAT_RGAS BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 0.0 to 0.4 0.2 Value from R1 V57. The default value 

was correctly returned.

PCS_T3 SAT_RGAS BRAGFLO LHS3_BF_AP161_R3_V042.CDB LIBAP161_BF 0.0 to 0.4 0.2 Value from R3 V42. The default value 

was correctly returned.
40

Table 3. Database-Code Interface Test Results for Parameters Used in the PCS-2012 PA that have 

Changed since PABC-2009

Material Name Property Name Code File Name Library PAPDB 

Value

Value 

Returned Comments

DRZ_ 1 CAP_MOD BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1 1 The correct value was returned.

DRZ_ PCS CAP_MOD BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1 1 The correct value was returned.

DRZ_ 1 COMP_RCK BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 7.41E-10 7.41E-10 The correct value was returned.

DRZ_ PCS COMP_RCK BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 7.41E-10 7.41E-10 The correct value was returned.

DRZ_ 1 KPT BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

DRZ_ PCS KPT BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

DRZ_ 1 PC_MAX BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1.0E08 1.0E08 The correct value was returned.

DRZ_ PCS PC_MAX BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1.0E08 1.0E08 The correct value was returned.

DRZ_ 1 PCT_A BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

DRZ_ PCS PCT_A BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

DRZ_ 1 PCT_EXP BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

DRZ_ PCS PCT_EXP BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

DRZ_ 1 PRMX_LOG BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -19.4 to -12.5 -13.05

Value from R2 V31. Sampled value 

correctly lies within the sampled range 

of -19.4 to -12.5.

DRZ_ 1 PRMX_LOG BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -19.4 to -12.5 -16.37

Value from R1 V57. Sampled value 

correctly lies within the sampled range 

of -19.4 to -12.5.

DRZ_ 1 PRMX_LOG BRAGFLO LHS3_BF_AP161_R3_V042.CDB LIBAP161_BF -19.4 to -12.5 -14.48

Value from R3 V42. Sampled value 

correctly lies within the sampled range

of -19.4 to -12.5.

DRZ_ 1 PRMY_LOG BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -16.0 -16.0 Value from R2 V31. The default value 

was correctly returned.

DRZ_ 1 PRMY_LOG BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -16.0 -16.0 Value from R1 V57. The default value 

was correctly returned.

DRZ_ 1 PRMZ_LOG BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -16.0 -16.0 Value from R2 V31. The default value 

was correctly returned.

DRZ_ 1 PRMZ_LOG BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -16.0 -16.0 Value from R1 V57. The default value 

was correctly returned.

DRZ_ PCS PRMX_LOG BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -20.699 to 

-17.0 -18.4

Value from R2 V31. Sampled value 

correctly lies within the sampled range 

of -20.699 to -17.0.

DRZ_ PCS PRMX_LOG BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -20.699 to 

-17.0 -17.79

Value from R1 V57. Sampled value 

correctly lies within the sampled range 

of -20.699 to -17.0.
41

Table 3. Database-Code Interface Test Results for Parameters Used in the PCS-2012 PA that have 

Changed since PABC-2009

Material Name Property Name Code File Name Library PAPDB 

Value

Value 

Returned Comments

DRZ_ PCS PRMX_LOG BRAGFLO LHS3_BF_AP161_R3_V042.CDB LIBAP161_BF -20.699 to 

-17.0 -19.53

Value from R3 V42. Sampled value 

correctly lies within the sampled range 

of -20.699 to -17.0.

DRZ_ PCS PRMY_LOG BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -18.7496 -18.7496 Value from R2 V31. The default value 

was correctly returned.

DRZ_ PCS PRMY_LOG BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -18.7496 -18.7496 Value from R1 V57. The default value 

was correctly returned.

DRZ_ PCS PRMZ_LOG BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF -18.7496 -18.7496 Value from R2 V31. The default value 

was correctly returned.

DRZ_ PCS PRMZ_LOG BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF -18.7496 -18.7496 Value from R1 V57. The default value 

was correctly returned.

DRZ_ 1 PO_MIN BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1.01325E05 1.01325E05 The correct value was returned.

DRZ_ PCS PO_MIN BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1.01325E05 1.01325E05 The correct value was returned.

DRZ_ 1 PORE_DIS BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.7 0.7 The correct value was returned.

DRZ_ PCS PORE_DIS BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.7 0.7 The correct value was returned.

DRZ_ 1 POROSITY BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0039 to 

0.0548 0.0129

Value from R2 V31. The default value 

was correctly returned. See text 

discussion.

DRZ_ 1 POROSITY BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 0.0039 to 

0.0548 0.0129

Value from R1 V57. The default value 

was correctly returned. See text 

discussion.

DRZ_ 1 POROSITY BRAGFLO LHS3_BF_AP161_R3_V042.CDB LIBAP161_BF 0.0039 to 

0.0548 0.0129

Value from R3 V42. The default value 

was correctly returned. See text 

discussion.

DRZ_ PCS POROSITY BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0039 to 

0.0548 0.0129 Value from R2 V31. The default value was correctly returned.

DRZ_ PCS POROSITY BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 0.0039 to 

0.0548 0.0129 Value from R1 V57. The default value was correctly returned.

DRZ_ PCS POROSITY BRAGFLO LHS3_BF_AP161_R3_V042.CDB LIBAP161_BF 0.0039 to 

0.0548 0.0129 Value from R3 V42. The default value was correctly returned.

DRZ_ 1 RELP_MOD BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1 or 4 4

Value from R2 V31. A value of 4 was 

returned in every sample whereas it 

should have only been returned an 

average of 67% of time. See text 

discussion.

DRZ_ 1 RELP_MOD BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 1 or 4 4

Value from R1 V57. Same comment as 

for R2 V31.

DRZ_ 1 RELP_MOD BRAGFLO LHS3_BF_AP161_R3_V042.CDB LIBAP161_BF 1 or 4 4

Value from R3 V42. Same comment as 

for R2 V31.

DRZ_ PCS RELP_MOD BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 1 or 4 0

Value from R2 V31. The default value 

was correctly returned.
42

Table 3. Database-Code Interface Test Results for Parameters Used in the PCS-2012 PA that have 

Changed since PABC-2009

Material Name Property Name Code File Name Library PAPDB 

Value

Value 

Returned Comments

DRZ_ PCS RELP_MOD BRAGFLO LHS3_BF_AP161_R1_V057.CDB LIBAP161_BF 1 or 4 0

Value from R1 V57. The default value 

was correctly returned.

DRZ_ PCS RELP_MOD BRAGFLO LHS3_BF_AP161_R3_V042.CDB LIBAP161_BF 1 or 4 0

Value from R3 V42. The default value 

was correctly returned.

DRZ_ 1 SAT_RBRN BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

DRZ_ PCS SAT_RBRN BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

DRZ_ 1 SAT_RGAS BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.

DRZ_ PCS SAT_RGAS BRAGFLO LHS3_BF_AP161_R2_V031.CDB LIBAP161_BF 0.0 0.0 The correct value was returned.
43

5.0 PARAMETER DATA ENTRY PROCESS REVIEW

Parameter data entry process and control were evaluated by reviewing the PDE forms used as the 

basis for data entry into the PAPDB, in accordance with SNL Procedure NP 9-2 Rev 01, 

Parameters. This procedure was most recently updated in August 2006 and is the same 

procedure that was reviewed by the Agency for PABC-2009. This procedure prescribes the 

processes for developing, documenting, controlling, and changing parameters used in 

compliance-level and programmatic PA calculations performed by SNL in support of the WIPP. 

Parameter values are required to be developed and documented in accordance with approved, 

procedurally driven planning documents. NP 9-2 Rev 01 provides detailed instructions for 

entering or changing a parameter value in the PAPDB. Responsibilities for checking and 

approval are clearly defined and appropriate. No concerns regarding this procedure were 

identified.

EPA also reviewed Activity Specific Procedure SP 9-5 Rev 01, Parameter Data Entry, for 

PABC-2009. This procedure has since been recalled, because data entry in PAPDB Version 2.00 

is accomplished directly by responding to prompts in the database input files. The master input 

file is called Parameter Database Data Entry. It presents a series of options for various tasks: 

identifying a new code; identifying new documents; defining new analyses; entering new 

parameters; and setting up a new analysis. Under the New Parameter button, for example, 

choices are given for adding a new material, adding a new property, adding a new parameter, 

adding parameter attributes, and adding parameter documentation. Under Add New Parameter, 

for example, the material name, property name, units, and reference type (such as reference 

constant) are entered. The Agency reviewed the data entry options and found them to be 

complete. Entries made through this system are manually checked for accuracy against the PDE 

forms and signed off. Additionally, the Agency found no problems related to the functioning of 

the PAPDB Version 2.00 in its database – code interface review. The new database appears to be 

working well and provides an enhancement over PAPDB Version 1.00.

Each PDE form for the 78 parameters that are new or have been changed since PABC-2009 was 

inspected by the Agency for completeness to confirm that all appropriate blanks were filled in 

and the necessary signatures were provided. Accuracy of the data entry process was checked by 

visually comparing the information on the form with the information shown in the online 

PAPDB. Although several errors were found in the documentation used to create the PDE forms, 

in none of the cases were errors found in the entered parameter values when compared to the 

forms. 

A review of the PDE forms supporting the parameter changes between PABC-2009 and PCS2012 determined that they were completely and correctly filled out. Handwritten changes were 

found on several forms correcting the associated metadata. These hand entries were dated and 

initialed by the originator of the form or by another responsible individual and were, therefore, 

acceptable.
44

6.0 COMPUTING HARDWARE

Run control for BRAGFLO is documented in Camphouse et al. (2012b). The calculations that 

were affected by the changes from PABC-2009 were updated, while the results from previous 

PAs were used for the calculations that were relatively unaffected by the changes. For PCS-2012 

calculations, the codes were executed on the WIPP PA Alpha Cluster consisting of 8 Hewlett 

Packard (HP) AlphaServer nodes configured to share the same disk array using Storage Area 

Network (SAN) technology for efficient disk utilization and data storage and management. This 

allows for highly distributed processing while providing for integrated data access. The WIPP 

PA Alpha Cluster runs the Open VMS operating system (Version 8.2). The node name and 

hardware description for the nodes used are provided in Table 4.

Table 4. WIPP PA Alpha Cluster Nodes Used in PCS-2012

Node Hardware Type Number of CPUs CPU Operating System

TBB HP AlphaServer ES47 4 Alpha EV7 Open VMS 8.2

TRS HP AlphaServer ES47 4 Alpha EV7 Open VMS 8.2

GNR HP AlphaServer ES47 4 Alpha EV7 Open VMS 8.2

MC5 HP AlphaServer ES47 4 Alpha EV7 Open VMS 8.2

CCR HP AlphaServer ES45 Model 2 4 Alpha EV68 Open VMS 8.2

TDN HP AlphaServer ES45 Model 2 4 Alpha EV68 Open VMS 8.2

BTO HP AlphaServer ES45 Model 2 4 Alpha EV68 Open VMS 8.2

CSN HP AlphaServer ES45 Model 2 4 Alpha EV68 Open VMS 8.2

Brine and gas flow in and around the repository and in overlying formations are calculated using 

the BRAGFLO suite of codes (PREBRAG, BRAGFLO, and POSTBRAG) in conjunction with 

several utility codes. Sampling of the uncertain parameters used by the various process model 

codes is performed with the PRELHS and LHS codes. PRELHS reads information about the 

ranges and distributions of the uncertain parameters from the PAPDB and formats this 

information for LHS. The LHS code implements the sampling algorithms. LHS is executed once 

per replicate. Each of the three replicates includes six scenarios designed to cover a range of 

drilling intrusion types and times. For each replicate/scenario combination, calculations are 

performed for 100 vectors of uncertain model input parameters. Additional run control 

information is provided by Camphouse et al. (2012b).
45

7.0 CONCLUSIONS

Although a number of database problems were identified in this review, none had a significant 

effect on the results of the PCS-2012 analysis. Of the approximately 1,700 parameters in the 

PAPDB, 78 changes were made since PABC-2009. Most of the changes involved the assignment 

of existing parameter names and values to newly defined materials used in the ROM salt PCS 

and newly defined time periods applied to the PCS DRZ. All PCS_T3 materials were new, 

because three different time periods had not previously been used in WIPP PA. Three data errors 

were identified in the PAPDB. All resulted from errors in source data tables and none resulted 

from transcription errors in preparing parameter data entry forms or in entering values into the 

PAPDB. However, none of these errors adversely affected PCS-2012 results.

A check of primary and secondary supporting documents was made for all parameter changes, 

and all documents were quickly retrieved from the WIPP Records Center. Many of the 

supporting documents were not found to adequately justify the parameter values used in the 

PCS-2012 analysis, and many had transparency weaknesses, because the cited source documents 

were prepared for other analyses and the associated metadata described those analyses rather 

than the PCS-2012 PA. 

A database interface evaluation was performed for all new parameters and the correct parameter 

values were retrieved from the PAPDB in all but one case, where the parameter was not sampled 

from the distribution described in the database. This error had no effect on the PCS-2012 PA 

results.

Procedures for developing, documenting, controlling, and changing parameters, and for entering 

those parameters into the PAPDB, were also reviewed. The Agency found all procedural changes 

to be consistent with earlier versions and found all revisions to be appropriate.

In summary, many more concerns were raised by this review than were raised in previous PA 

parameter reviews. However, as documented in this report, the Agency’s concerns address 

details of the PCS-2012 PA database that did not affect the overall results.
46

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