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40 CFR 194.15(A)(2) MONITORING 1-15-1 Water Level Fluctuations in SNL-13. DOE/WIPP-12-3489 p. 143 states "SNL-13 was also excluded [from the Culebra groundwater analysis] due to a sudden rise and then sudden stabilization following the drilling of a new oil or gas well nearby." Please address the following:1. Identify and provide the location, depth, and purpose of the 'new' nearby wells.2. What activities took place at the nearby wells during the time of the changes in SNL-13, such as fluid injection? Provide pressure histories, volumes and fluid types, fluid enhancements (e.g. fracking fluids or proppants).3. Provide a chronological history of the activities in the nearby wells compared to the "sudden" changes in adjusted freshwater heads recorded in SNL-13.4. Were water levels in other monitoring wells influenced by activities at nearby wells?40 CFR 194.15(A)(2) MONITORING 1-15-2 Shaft Extensometers Not Taking Recordings. DOE is not replacing the failed monitoring instruments in the shaft. However, EPA Section 42, Monitoring requirements expects, " ...extent of deformation ..." and "...brittle deformation... " to be monitored. Please provide a justification to discontinue measuring these characteristics in the WIPP shafts as these measurements are used to calibrate numerical models and predict closure rates. Additionally, identify how this requested information will be addressed in the future.

EPA's Completeness Questions Received December 17, 2014

Status Report of DOE Responses to EPA Completeness Questions

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40 CFR 194.15(A)(2) MONITORING 1-15-3 Derivation of Annual Culebra Water Level Map. CRA-2014 Section 42.8 Changes or New lnformation Since the CRA-2009 discusses changes to the process used to derive the 

Culebra groundwater flow parameters that is used to prepare the annual water level map. Please address the following:1. For each yearly calculation (ERMS 558589, Section 2.3.2.2), if the monitored freshwater heads have changed, do the 100 calibrated T-Fields need to be recalculated? If not, why?2. ERMS 557633 Section 2.1 states, "The PA MODFLOW model T (transmissivity), A (anisotropy) and R (recharge) input fields are appropriately averaged across 100 realizations, producing a single average MODFLOW flow model." Provide information as to how averaging is done with examples.3. For the averaged MODFLOW model, T (transmissivity), A (anisotropy) and R (recharge) are fixed while a subset of the boundary conditions is modified (ERMS 557633, Section 2.1). Please describe how the new boundary conditions are determined and implemented. If this simply involves raising or lowering the heads along the boundaries to best match the observed water levels within the modeled area, describe how well the assigned boundaries honor the water levels in the nearest monitoring wells both inside and outside the model area.4. If the step-by-step creation of the annual Culebra water level map is the same as that provided during 2012 and 2013 inspections, please denote as such. If generating the annual water level map differs from what has been provided during inspections, please provide these steps.

40 CFR 194. 23 MODELS AND COMPUTER CODES1-23-1 Continuing Validity of Kds. CRA-2014 Appendix PA, Table PA-1 states that the Culebra Matrix Partition Coefficients (Kds) are, " Carried over from CRA-2009 PABC ." Please provide the rationale for the assumption that the CRA 2014 Kds can be same as those used in the CRA-2009 despite the changes in the organic ligand content and the 2012 inventory since the last PA. Additionally, provide a discussion of the potential impacts of the organic kitty litter added to the LANL waste on the Culebra Kds.

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40 CFR 194. 23 MODELS AND COMPUTER CODES1-23-2 Continuing Validity of T-Fields. CRA-2014 Appendix PA, Table PA-1 states that the Culebra Transmissivity Fields are, " Carried over from CRA-2009 PABC ." It 

appears that the last update to the geologic well data analysis was performed in 2007 (Powers 2007a and Powers 2007b). Specificquestions and requests the Agency has related to the T-Fields are listed below. 1. Have changes in the Culebra well data during the past seven years changed the T-Field derivation in any way?2. Has any additional hydraulic testing been performed that could be used for additional calibration of the T-Fields?3. Has the saturated thickness of the Culebra remained constant since the original derivation of the T-Fields?4. Provide justification that new well information and water level changes since the 2009 PABC do not need to be included in the TField derivation and that the 2009 T-Fields are still valid for use in the CRA-2014 PA.5. Provide justification for the continued use of the CRA-2009 T-fields.

40 CFR 194. 23 MODELS AND COMPUTER CODES1-23-3 REGION ROMPCSThe Agency agreed to the adopted parameter values used for the panel closure change request to isolate the effects and facilitate a comparison of the proposed panel closure design on the baseline PA and, at the time of the planned changed request, there wasuncertainty in the emplacement technique to be used. The Agency would like DOE to address the following comments on several parameters related to the panel closures:1. Identify and technically justify that ranges of porosity and permeability for the ROM salt PCS during the time period 0 to 100 years (material PCS_T1) are consistent with initial emplacement of the ROM salt material without wetting or compaction.2. Provide technical justification for applying a capillary pressure model that assumes zero threshold pressure to region ROMPCS during time periods 100 to 10,000 years (T2 and T3).3. Provide a technical justification for selecting the ranges for the residual brine and gas saturations (SAT_RBRN and SAT_RGAS) during time periods T2 and T3; the justification should include adopting a zero value as the low end.4. Provide technical justification for using the same value for the bulk compressibility of ROM salt during the T1, T2 and T3 time periods (from 0 to 100, 100 to 200, and 200 to 10,000 years).

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40 CFR 194. 23 MODELS AND COMPUTER CODES1-23-4 REGION DRZ PCSThe Agency would like DOE to address the following comments related to the parameter values adopted for the DRZ_PCS:1. Provide technical justification for assigning the same sampled value of porosity to the material in DRZ_PCS region for both early and late time periods (T2 and T3) when the DRZ is undergoing consolidation and healing.2. Provide technical justification for the apparent discrepancy created by independently sampling the permeability of material DRZ_PCS, representing a healed DRZ, from a distribution that can provide a sampled permeability as much as seven orders of magnitude higher than the permeability of intact halite.3. Provide technical justifications for assigning zero values to the residual brine and gas saturations (SAT_RBRN and SAT_RGAS) in CRA-2014 for the region DRZ_PCS during the T3 time period (200 to 10,000 years).4. Provide technical justification for applying a capillary pressure model that assumes zero threshold pressure in region DRZ_PCS during the T3 time period (200 to 10,000 years).5. Provide technical justification for the value of the bulk compressibility of the DRZ_PCS region, and applying that same value during both early and late time periods (T2 and T3) when the material in that region is undergoing consolidation.

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40 CFR 194. 23 MODELS AND COMPUTER CODES1-23-5 Waste Shear Strength. Please address the following:1. Provide horsetail plots of the remaining fraction of uncorroded iron in the repository throughout the 10,000-year regulatory time frame from the CRA-2009 PABC from each of the three replicates and each scenario.2. Provide horsetail plots of the remaining fraction of undegraded CPR in the repository throughout the 10,000-year regulatory time frame from the CRA-2009 PABC from each of the three replicates and each scenario.3. Provide and justify the criteria used in advancing the surrogate waste samples during the shear strength tests when the eroded sample face was not smooth but irregular.4. Identify and justify the consequences of using the proposed uniform distribution rather than the currently approved log-uniform distribution for TAUFAIL.5. Provide the quality control procedures used during the shear strength tests and provide evidence that the tests were performed consistent with those procedures.

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40 CFR 194. 23 MODELS AND COMPUTER CODES1-23-6 Probability of Encountering a Castile Brine Pocket. Please address the following comments:1. TDEM results are site specific and indicate the presence of potentially large volumes of brine beneath some waste panels. Explain why TDEM data is not used in DOE's proposed approach for estimating PBRINE.2. DOE's approach ignored the presence of high electrical conductivity zones identified beneath four of the ten WIPP waste panels. Please explain how this omission affected the comparison of the TDEM approach with DOE's newly derived drilling data approach.3. ERMS 558724 asserts that brine encounters of sufficient size to impact the repository would be noticed and logged by a driller. The approach does not acknowledge the potential of encountering a low yield and high volume brine pocket which would not be noticed by the driller in calculating PBRINE. Please address the basis for not considering the low yield, high volume brine pockets.4. DOE reported the same count of 34 brine intrusions out of 678 Castile wells in 2008. It is unclear whether 2008 was the last time a brine intrusion was observed at the time of collecting data for the CRA-2014 or if 2008 was the cut-off date for recoding a brine intrusion. Please clarify.5. The circular regions in Figure 5 of ERMS 558724 were selected to include a known brine pocket encounter. Please provide information as to whether this radius would bias the results and the sensitivity of the results to the radius size.6. Provide information as to how the well depths, for each well that did and did not encounter a brine pocket, were incorporated into the drilling data analysis.7. The ratios in Table 2 of ERMS 558724 include double-counting of many wells. Please provide information as to how this affected the results.8. ERMS 558724 states that pressurized brine is associated with near-vertical fractures. However, WIPP-12 yielded large volumes of brine that is assumed to have been stored and transmitted through the extensive and primarily interconnected horizontal to sub-horizontal fractures. Please provide an explanation as to how the near-vertical fracture model adopted by DOE's modified PBRINE parameter is consistent with evidence that WIPP-12 releases are attributed to horizontal and sub-horizontal fractures.

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40 CFR 194. 23 MODELS AND COMPUTER CODES1-23-7. Volume of Repository Operations and Experimental Areas. Please address the following:1. Explain how DOE arrived at a volume of 148,011 m3 for the underground.

2. In the diagram of repository ventilation during recovery (see attached, labeled Phase 2B Underground Map , dated 

March/17/2014) a large portion of the north experimental area is denoted as 'backfilled'. Please provide information of the material properties of these backfilled areas and how they are modeled during the 10,000 year regulatory period in the CRA-2014 PA.

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40 CFR 194.23 MODELS AND COMPUTER CODES1-23-8 Fluid Flow in Repository Operations and Experimental Areas. There have been numerous refinements of conceptual and numerical models of repository fluid flow since the 1994-95 time frame as well as changes to the panel closure system that may also change repository fluid flow. Please provide updated technical justifications for the following parameter values adopted for the experimental and operations areas:1. Setting the permeability of the operations and experimental rooms to a constant value of value 10 -11 m2 throughout the modeled 

period.2. Setting the porosity of the operations and experimental rooms to a constant 18%throughout the modeled period.3. Setting the porosity and permeability of the DRZ adjacent to the operations and experimental room to the same sampled value as the DRZ surrounding a waste panel throughout the modeled period.

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40 CFR 194.23 MODELS AND COMPUTER CODES1-23-11 EQ3/6 and Supporting Files. Please provide the following computer files related to the actinide source term modeling calculations and the determination of the cumulative distribution functions for the actinide solubilities:1. The EQ3/6 database file DATA0.FM1 used for the CRA-2014 solubility calculations, (also known as DATA0.FMT.R2).2. EQ3/6 input and output files used for calculating actinide solubilities for the actinide source term at different brine volumes (1x, 2x, 3x, 4x, 5x minimum brine volumes).3. The Excel macro GetEQData.xls and all Excel spreadsheets that contain the output extracted with GetEQData.xls.4. EQ3/6 input and output files used for calculating actinide solubilities for the +III and +IV actinide uncertainty analysis calculations.5. Excel macros GetEQData_v101e.xls and GetEQData_v101f.xls; and6. Excel files Thorium_Uncertainty_Results_2014_PA.xls andAmericium_Uncertainty_Results_2014_PA.xls.40 CFR 194.23 MODELS AND COMPUTER CODES1-23-12 WIPP-Specific Organic Complexation Data. Appendix SOTERM Section 3.8.2 provides a description and four graphs (Figure SOTERM-21) that relate to WIPP-specific experiments designed to evaluate the effects of organic chelating agents on +III and +IV actinide solubility in WIPP brines.1. Please provide supporting documentation for these data, including a summary of the experimental approach, materials and analytical methods used to produce the data.2. Please provide any available characterization data for the solid phases present in these experiments.

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40 CFR 194.23 MODELS AND COMPUTER CODES1-23-13 Missing Reference. Appendix SOTERM, Figure SOTERM-7 caption cites Altmaier (2011) but this reference is missing from the reference list. Please provide this reference.40 CFR 194.24 WASTE CHARACTERIZATION- PERFORMANCE ASSESSMENT INVENTORY1-24-1 Shielded Container Lead Inventory1. Please provide information as to how lead shielding on RH shielded containers is included in the performance assessment. 40 CFR 194.24 WASTE CHARACTER IZATION- PERFORMANCE ASSESSMENT INVENTORY1-24-2 Inventory Report Text Unclear. Please address the following:1. Provide information as to how the "projected-to-stored volume ratio" is derived for both RH and CH waste. Please provide anexample of this derivation.2. Provide information of the RH waste volume that has been and will be placed in the leaded containers on the waste panels floors.3. Provide information that specifies how potential waste inventory listed in the inventory report estimate is used in the CRA-2014 performance assessment.40 CFR 194.24 WASTE CHARACTER IZATION- PERFORMANCE ASSESSMENT INVENTORY1-24-3 Emplaced Inventory Chemical Constituents1. In the ATWIR 2012, Section 2.3, it is stated that, "Chemical constituents are not reported in the emplaced inventory". In the PAIR 2012 report, Section 4.3, it is indicated that "two additional analysis" were performed for chemical and other important constituents. It is unclear how the chemical constituents of emplaced inventory, identified in the PAIR report, are derived andcalculated for the CRA-2014 PA, provide clarification.

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40 CFR 194.24 WASTE CHARACTER IZATION- PERFORMANCE ASSESSMENT INVENTORY1-24-4 Missing References. Please provide the following references:French, D. 2009. Analysis of Container Material Masses , INV-SAR-19. Los Alamos National Laboratory - Carlsbad Operations, Carlsbad, NM.Los Alamos National Laboratory - Carlsbad Operations (LANL-CO) 2010. Analyses , LCOQP9 - Los Alamos National Laboratory - 

Carlsbad Operations, Carlsbad, NM.Los Alamos National Laboratory - Carlsbad Operations (LANL-CO) 2011a. Data Collection, Data Management, and Control for the Comprehensive Inventory , INV-SP-01. Los Alamos National Laboratory - Carlsbad Operations, Carlsbad, NM.Los Alamos National Laboratory - Carlsbad Operations (LANL-CO) 2011b. Entry, Verification, and Validation of inventory Information in the Comprehensive Inventory Database , INV-SP-02. Los Alamos National Laboratory - Carlsbad Operations, Carlsbad, NM.Los Alamos National Laboratory - Carlsbad Operations (LANL-CO) 2011c. LANL-CO Software Quality Assurance Plan , LCO-QPD02. Los Alamos National Laboratory - Carlsbad Operations, Carlsbad, NM.Los Alamos National Laboratory- Carlsbad Operations (LANL-CO) 2011d. Software Quality Assurance , LCO-QP19-1. Los Alamos National Laboratory - Carlsbad Operations, Carlsbad, NM.Los Alamos Nationa! Laboratory - Carlsbad Operations (LANL-CO) 2011e. Comprehensive Inventory Database , Version 2.0, 

Schema Version S2.00, Data Version D.10.01. Los Alamos National Laboratory - Carlsbad Operations, Carlsbad, NM.Los Alamos National Laboratory - Carlsbad Operations (LANL-CO) 2012. Comprehensive Inventory Database , Version 2.01, Schema Version S2.01, Data Version D.11.00. Los Alamos National Laboratory - Carlsbad Operations, Carlsbad, NM.Chemical and Cement Components 2011 Inventory Estimates . LANL-CO. INV-SAR-28, Revision 0, November 1, 2012. LANL-CO Record ID# INV-1211-01-01-01.Estimation of Cellulose, Plastic, and Rubber Emplacement Materials in the Waste Isolation Pilot Plant (WIPP) . LANL-CO. INV-SAR27, Revision 0, November 5, 2012. LANL-CO Record ID# INV-1211-02-01-01.GENERAL: CRA-2014 DOCUMENTATION1-G-1 Reference Appendix QAPD-2014 Not Provided. CRA-2014 Section 23, Models and Computer Codes, Section 23.5.7 states, "The DOE's quality assurance program, as applied to the CRA-2014, is contained in Appendix QAPD-2014." The appendix has not been provided. Please provide this document.

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GENERAL: CRA-2014 DOCUMENTATION1-G-2 Codes IDs Do Not Include Source Code Listing. CRA-2014 Section 23, Models and Computer Codes, Section 23.8.7 states, "The IDs include source-code listings..." EPA examined a number of code Implementation Documents; they include a reference to the location of the source-code listing, but not the actual listing of the code. Please provide the source-code listing for the following CRA-2014 codes: BRAGFLO 6.02, MATSET 9.20, CCDFGF 6.0.

GENERAL: CRA-2014 DOCUMENTATION1-G-3 New Codes EQ3/6 and JAS3D Documentation Incomplete. DOE states in CRA-2014 Section 23, 23.7.7, "The documentation for the new codes EQ3/6 and JAS3D may be found in their respective UM, AP, VD, ID, and RD/VVP." It does not appear that this documentation has been included in CRA-2014. Please provide this documentation.CHEMISTRY COMMENTS1-C-1 LANL Waste Stream With Added Cellulosic Material.Organic kitty litter was used as an absorbent for nitrate salts for Waste Stream LA-MIN02-V.001 (NMED 2014) and 349 drums of this waste were placed in Panels 6 and 7 (Wallace 2014). Please address the following:1. Provide a complete waste profile for the kitty litter; including; cellulosic content and other ingredients; emplaced volume and mass.2. Specify the number of drums with kitty litter placed in either Panel 6 or 7.3. Identify the type of waste emplaced in the drums with the kitty litter.4. Indicate whether this cellulosic kitty litter has been used in other waste streams and whether the corresponding waste profile reports adequately describe the waste material parameters.5. Describe the effects of omitting the organic kitty litter in the waste stream(s) on the CPR inventory and consequent effects on gas generation rates calculated for the CRA-2014 PA.6. Provide information of the quantities of soluble organics, such as organic ligands or surfactants that could affect actinide solubilities when this material is leached.

194.23 MODELS AND COMPUTER CODES2-23-1 ROM Salt Panel Closures Locations. Please provide the WIPP configuration layout (a plan view) used for the 2014 CRA that includes all locations where the ROM saltpanel closures are to be placed. Provide text that provides the exact location, dimensions and properties for the set of panel closures that lie furthest north in the repository.

EPA's Completeness Questions Received February 27, 2015

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194.23 MODELS AND COMPUTER CODES2-23-2 Provide An Update of the Derivation of the Shaft Properties at the Repository Horizon. In the BRAGFLO grid for the 2004 and 2009 CRA Performance Assessments (PAs), the modeled lower portion of the shaft included an effective permeability that incorporated both the concrete portion of the shaft (at the repository horizon level) and the furthest north panel closures located just south of the waste and exhaust shafts. The material properties of the modeled shaft (the concrete monolith segment) were combinations of the shaft properties and the Option D panel closure properties (Camphouse and Clayton 2011, ERMS 555204). Now, however, there is a new panel closure system that uses run of mine salt instead of the Option D design, and the properties of new panel closure system are different than that of the concrete portion in the lower shaft. In the CRA 2014 PA, however, it appears the material properties of the shaft at the repository horizon have not been updated to reflect the change. Please confirm this and identify how the properties would change to reflect the change in the panel closure design.194.33 FUTURE DRILLING2-33-1 Future Drilling Into Nitrate Waste. Please provide the probability and describe the potential consequence(s) to PA calculations of drilling into the nitrate waste. 194.43 PASSIVE INSTITUTIONAL CONTROLS 2-43-1 Changes in Passive Institutional Controls (PICs). Recent Nuclear Energy Agency and International Atomic Energy Agency reports describe changes and developments in international approaches to PICs. These are referenced in INIS-US-13-WM-13145 which states “The DOE/CBFO WIPP PIC's program in place today meets the regulatory criteria, but complete feasibility of implementation is questionable, and may not be in conformance with the international guidance being developed.” Please explain this feasibility concern. Please also provide the complete INIS-US-WM-13145 report (the Web link only provides an Abstract) and any other recent studies or reports that may impact PICs planning in the future. Reference: INIS-US-13-WM-13145, “The Revised WIPP Passive International Controls Program – A Conceptual Plan – 13145, Dated 2013-07-01, Web link: http://www.osti.gov/scitech/biblio/22225507

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194.44 ENGINEERED BARRIERS 2-44-1 MgO Physical Segregation. In Franco (2012) DOE notified EPA that MgO emplacement has been modified by placing a 3,000 pound supersack of MgO on every other waste stack or on each waste stack in every other row. In the Franco 2012 letter the “effective diffusion penetration length of CO2” was considered but the information on physical segregation is limited. Please provide updated documentation to more explicitly and clearly address whether the larger lateral separation distance still allows sufficient reactions between MgO and CO2. References: Franco, J.R. 2012. Letter to A. Perrin (Subject: “Planned Change Notice for Placement of MgO Supersacks," withenclosure (Analysis of an alternative placement scheme for MgO supersacks). February 14, 2012. Carlsbad, NM: U.S. Department of Energy Carlsbad Field Office. U.S. Department of Energy (DOE). 2009. Title 40 CFR Part 191 Subparts B and C Compliance Recertification Application for the Waste Isolation Pilot Plant, Appendix MgO-2009. Magnesium Oxide as an Engineered Barrie r. 

DOE/WIPP 09-3424. Carlsbad, NM: Carlsbad Field Office. Vugrin, E.D., M.B. Nemer, and S.W. Wagner. 2006. Uncertainties Affecting MgO Effectiveness and Calculation of the MgO Effective Excess Factor (Rev. 0, November 17). ERMS 544781. Carlsbad, NM: Sandia National Laboratories.

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194.46 REMOVAL OF WASTE2-46-1 CCA Appendix WRAC Waste Removal Documentation Needs Updating. The cited removal plan is basically the same as that given during the 1996 CCA and does not reflect updates and modifications to the repository design and waste characteristics. The Agency found discrepancies between what was used as the removal plan listed in 1996 CCA Appendix WRAC, “Waste Removal after Closure,” with the current 2014 repository design, waste, and container characteristics. These are listed below. Please update the waste retrieval plan to address these discrepancies. Please assure that 40 CFR 194.46 requirements “Removal of Waste” still comply and are aligned with expected repository conditions at the time of closure, and that removal of waste remains feasible. The repository is no longer mined on one contiguous level [CCA Appendix WRAC page WRAC-7], the southern portion of the mine was moved up to the Clay Seam G level. The waste containers have changed. The CCA assumed two principal types of containers (55-gallon drums and standard waste boxes) [CCA Appendix WRAC, page WRAC-8] but with the introduction of large waste boxes, shielded RH-TRU containers, pipe over packs, and super-compacted waste, these assumptions are no longer valid. The waste characteristics have changed with the introduction of nitrate waste potentially subject to exothermic reactions. The run-of-mine salt panel closure replaced the original concrete-based Option D panel closure design, which can no longer be used “as markers for locating panels and drifts” [CCA Appendix WRAC, Section WRAC.6.4]. Given the use of shielded containers CH and RH wastes no longer must be segregated in the waste panels [CCA Appendix WRAC, Sections WRAC.4.3, WRAC.6, WRAC.6.4] and can no longer be removed using separate retrieval operations where the RH shielded containers are comingled with CH waste containers. CCA Appendix WRAC refers to performance assessment (PA) modeling to predict future characteristics of repository waste rooms. The PA assumptions, models, parameters, and inventory have changed since the CCA. Please include these changes in the waste removal reevaluation. CCA Appendix WRAC, Section WRAC.4.3 takes credit for the effectiveness of active and passive controls to deter human intrusion for up to 700years after closure. However, this credit was denied by EPA because of difficulty predicting the future. This should be removed from the waste removal reevaluation. References: U.S. Department of Energy (DOE). 1996. Title 40 CFR Part 191 Compliance Certification Application for the Waste Isolation Pilot Plant (October). CCA Appendix WRAC, Waste Removal After Closure”. DOE/CAO-1996-2184. Carlsbad, NM: Carlsbad Area Office. U.S. Department of Energy (DOE). 1996. Title 40 CFR Part 191 Compliance Certification Application for the Waste Isolation Pilot Plant (October). CCA Chapter 7.0, “Assurance Requirements”. DOE/CAO-1996-2184. Carlsbad, NM: Carlsbad Area Office. U.S. Department of Energy (DOE). 2004. Title 40 CFR Part 191 Compliance Recertification Application for the Waste Isolation Pilot Plant (March). CRA-2004 Chapter 7.0, “Assurance Requirements”. DOE/WIPP 2004-3231. Carlsbad, NM: Carlsbad Field Office. U.S. Department of Energy (DOE). 2009. Title 40 CFR Part 191 Compliance Recertification Application for the Waste Isolation Pilot Plant (March). CRA-2009 Section 46, “Removal of Waste” DOE 09-2434. Carlsbad, NM: Carlsbad Field Office.

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194.55 RESULTS OF COMPLIANCE ASSESSMENTS 2-55-1 Incorrect Reference. Appendix IGP-2014, Section IGP-2.1 makes reference to 194.55(b)(1), should this be 194.54(b)(1) “Existing boreholes...”? CHEMISTRY COMMENTS2-C-3 Data Supporting Water Balance Assumptions. The CRA-2014 PA calculations include the effects of MgO hydration, microbial degradation of CPR and iron sulfide formation on repository water balance. For PA, it is assumed that hydrogen sulfide created by CPR degradation preferentially reacts with iron hydroxide versus metallic iron (CRA-2014 Appendix MASS, page MASS-57). These hydrogen-sulfide reactions are: Fe(OH)2(s) + H2S(g) → FeS(s) + H2O(l) (1) Fe(s) + H2S(g) → FeS(s) + H2(g) (2) The assumption that hydrogen sulfide preferentially reacts with 

iron hydroxide increases brine production and decreases gas production compared to the assumption that all or some of the hydrogen sulfide reacts with metallic iron. It is also assumed for PA that carbon dioxide preferentially reacts with brucite instead of unreacted MgO. The carbonation reactions are:1.25 Mg(OH)2(s) + CO2(g,aq) → 0.25 Mg5(CO3)4(OH)2•4H2O(s) (3)1.25 MgO(s) + CO2(g,aq) + 1.25 H2O(l) → 0.25 Mg5(CO3)4(OH)2•4H2O(s) (4) The assumption that carbon dioxide preferentially reacts with brucite increases brine production in the repository. Please provide supporting data for these water-balance assumptions and evaluate the potential magnitude of the effects of these assumptions on the water balance.

CHEMISTRY COMMENTS2-C-4 Hydromagnesite Conversion Rate. Clayton (2013) formulated the conversion reaction from hydromagnesite to magnesite for inclusion in the BRAGFLO calculations as:Mg5(CO3)4(OH)2•4H2O(s) → 4 MgCO3(s) + Mg(OH)2(s) + 4 H2O(l) (5) Clayton (2013) calculates a range for the hydromagnesite conversion rate based on reaction times of 100 years to 10,000 years. However, the minimum reaction time for this conversion is uncertain. SCA (2008) reviewed the available experimental and natural analogue data and concluded that hydromagnesite conversion is best represented by a range of zero conversion (only hydromagnesite remains after 10,000 years) tocomplete conversion (only magnesite remains after 10,000 years), with a uniform distribution across this range. Please provide an explanation as to why the specific upper and lower limits used in the PA were picked. The effect of using zero rather than 100years as the minimum conversion rate is likely to be less brine production in the water balance, based on equation (5). Please provide an explanation of the effects on PA if the lower limit of the hydromagnesite conversion rate is set to zero while the upper limit is decreased by a variety of plausible factors that are less than what Clayton had adopted. References: Clayton, D.J. 2013. Justification of Chemistry Parameters for Use in BRAGFLO for AP-164, Rev. 1. Sandia National Laboratories, ERMS 559466. SCA (S. Cohen and Associates). 2008. Review of MgO-Related Uncertainties in the Waste Isolation Pilot Plant. Final Report prepared for the U.S. Environmental Protection Agency Office of Radiation and Indoor Air, Washington, D.C., January 24, 2008.

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CHEMISTRY COMMENTS2-C-5 Cumulative Effects of Water Balance Assumptions on PA. The result of several water balance assumptions is to increase brine production from waste reactions in the repository. These assumptions include that hydrogen sulfide will preferentially react with iron hydroxide instead of metallic iron (Comment 2-C-3); that carbon dioxide will preferentially react with brucite instead of MgO (Comment 2-C-3); and that the minimum rate of hydromagnesite conversion to magnesite is greater than zero (Comment 2-C-4). Please provide a description of the cumulative effects of these assumptions on the water balance calculations for the CRA-2014 PA.CHEMISTRY COMMENTS2-C-6 MgO Hydration Rate. MgO has been supplied for the WIPP engineered barrier by three vendors: National Magnesia Chemicals, Premier Chemicals, and, currently, from Martin Marietta Magnesia Specialties (Martin Marietta). The majority of the MgO in the repository is from Premier Chemicals and Martin Marietta. Clayton (2013) used MgO hydration rates obtained from experiments conducted with MgO supplied by Premier Chemicals to establish the hydration rates used in PA. However, Wall (2005) performed preliminary tests with the Martin Marietta MgO and concluded that it reacted to form brucite faster than Premier MgO. Given the multiple vendors that supply MgO a summary of the following information needs to be provided; The inundated and humid MgO hydration rates for MgO from the three vendors. The potential effects of the variable MgO hydration rates on repository performance. The amounts of National Magnesia Chemicals, Premier MgO and Martin Marietta MgO that will be present in the WIPP repository at the time of closure, and assumptions regarding the future source(s) of MgO. References: Clayton, D.J. 2013. Justification of Chemistry Parameters for Use in BRAGFLO for AP-164, Rev. 1. Sandia National Laboratories, ERMS 559466. Deng, H., M. Nemer, and Y. Xiong. 2007. Experimental Study of MgO Reaction Pathways and Kinetics Rev. 1. Sandia National Laboratories TP 06-03.Deng, H., Y. Xiong, M. Nemer and S. Johnsen. 2009. Experimental Work Conducted on MgO Long-Term Hydration. Sandia National Laboratories ERMS 551421. Wall, N.A. 2005. Preliminary Results for the Evaluation of Potential New MgO. Sandia National Laboratories ERMS 538514.CHEMISTRY COMMENTS2-C-7 MgO Hydration Rate Data File. Please provide a copy of the Microsoft Excel file “hydration kinetics Q & HY2 & HH djc 5-1-07.xls” used by Nowak and Clayton (2007) to calculate the MgO hydration rates. References: Nowak, E.J. and D. Clayton. 2007. Analysis of MgO Hydration Laboratory Results and Calculation of Extent of Hydration and Resulting Water Uptake versus Time under Postulated WIPP Conditions. Sandia National Laboratories ERMS 546769.

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CHEMISTRY COMMENTS2-C-8 Iron and Lead Corrosion Rate Data. Please provide spreadsheets containing the iron and lead corrosion data listed in Appendix A, Tables A-1 and A-2 from Roselle (2013). References: Roselle, G.T. 2013. Determination of Corrosion Rates from Iron/Lead Corrosion Experiments to be Used for Gas Generation Calculations. Sandia National Laboratories ERMS 559077.

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194.32 SCOPE OF PERFORMANCE ASSESSMENT Since the original certification decision changes have been made to the repository, it is our observation that, for many of thefeatures, events, and processes (FEPs) we have reviewed, DOE has not fully considered all of the relevant changes to the repository. Additionally, DOE has not fully considered updates relevant to activities within the WIPP vicinity. Table FEP-1 lists our comments on specific FEPS; immediately below we discuss general FEP screening issues that need further attention. 2-32-G1 Obsolete FEP Screening Arguments, Curtailed FEP Screening Arguments, and Completeness Considerations. The screening arguments in the CRA-2014, Appendix SCR- 2014 for many FEPs have been carried forward from past baseline reviews and do not necessarily reflect changes that have occurred in the past several years. This especially applies to information on how some FEPs are accounted for in PA. Some FEPs need to be updated to reflect current repository design and new knowledge of repository behavior. These are identified in Table FEP-1. For some FEPs, the screening argument needs to provide amore complete discussion of the FEP and how it is determined to be screened-in or screened-out. The supporting arguments, alongwith documents incorporated by references, need to provide a basic understanding of how the FEP is accounted for in PA calculations, where the FEP is accounted for in the repository region and surrounding geosphere, and when in the regulatory time frame the FEP is accounted for. Those FEPs with inadequate or curtailed screening arguments are provided in Table FEP-1. For some FEPs that DOE has reported "no change", EPA disagrees and believes that DOE should reconsider and update the FEP discussion. Table FEP-1 includes those FEPs in this category that EPA has identified, to date, as being incomplete.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S1. Screening argument considers only boreholes intersecting the waste region. Please supplement the argument with a discussion of boreholes that intersect the non-waste regions and the consequence to PA calculations. Provide references and specific information as to whether boreholes penetrating non-waste regions could result in the transport of radionuclides between the waste and non-waste regions, to overlying units, or to the surface. Provide information, either directly or by reference, as to how deep boreholes penetrating the non-waste and waste regions of the repository are accounted for in the PA.

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194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S2. The screening argument considers flow into the repository from boreholes that intercept pressurized fluid in underlying formations but only for boreholes intersecting the waste region. In the current BRAGLO model gas and brine readily flow between the waste and non-waste regions. A discussion and analysis of boreholes that could intersect the non-waste regions and their impact on the PA needs to be provided.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S3. Screening argument considers only boreholes intersecting the waste region and also pressurized Castile brine. In the current BRAGLO model gas and brine readily flow between the waste and non-waste regions . Please supplement the argument with a 

discussion and analysis of boreholes that could intersect the non-waste regions on the PA.

194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S4. Please address whether enhanced production techniques are being used in the Delaware basin and in the vicinity of WIPP. Please also address the potential for these techniques to create a preferential pathway for radionuclide releases through a second well.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S5. This FEP is screened out partially on the basis that solution mining will not occur in low ambient temperature conditions. However, solution mining is occurring in the nearby Eddy mine under similar conditions that exist in the vicinity of WIPP. Please provide text that reconciles the basis of the screening argument and the conditions at the Eddy mine where solution mining is taking place.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S6. In the screening argument please provide evidence that the modeled excavated volume is the expected mined volume of the underground workings at the time of closure.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S7. The screening argument citation of the CCA as the source of information on the Heterogeneity of waste forms ignores changes that have occurred in the past 15 years, including supercompacted waste and mingling RH waste in shielded containers with CH waste. Please update the information to reflect current waste forms.

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194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S8. Please supplement the screening argument with an explanation of the implementation in PA of the material inventory of shielded containers containing RH waste.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S9. The screening argument for this FEP states “This excavation-induced, host-rock fracturing is accounted for in PA calculations (the CCA, Chapter 6.0, Section 6.4.5.3).” The cited CCA text indicates that the DRZ is modeled in the same way around all repositoryexcavations. However, the DRZ is now expected to vary spatially. Provide an updated description of the DRZ in the waste and nonwaste locations of the repository.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S10. Screening argument was combined with that for W18 Disturbed Rock Zone(DRZ); please see comments for FEP W18.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S11. Please supplement the screening argument with a discussion of salt creep and consolidation specific to the ROM salt in the ROMPCS, and healing of the adjacent DRZ. Such a discussion can be found in Camphouse et al. (2012, Section 2.0. ERMS 557396). The screening argument for this FEP states that “Salt creep in the Salado is accounted for in PA calculations (the CCA, Chapter 6.0, Section 6.4.3.1).” The cited CCA section discusses these FEPs only in the context of the waste region. In addition, this is the only FEP that addresses DRZ healing, which is expected to vary spatially.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S12. Screening argument was combined with that for W20 Salt Creep ; please see comments for FEP W20. Additionally, please supplement the screening argument with discussions of 1) the coupling between consolidation of the ROM salt in the ROMPCS and healing of the adjacent DRZ (DRZ healing cannot occur until the ROM salt is consolidated and applies a back stress sufficient to compress and heal the DRZ); and 2) lateral extrusion of the ROM salt when under compressive stress from drift creep closure.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S13. Please supplement the screening argument with a discussion of the potential for high waste panel gas pressures to delay the consolidation of the ROM salt, thereby maintaining a higher permeability in the PCS for a longer period of time.

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Status Report of DOE Responses to EPA Completeness Questions

194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S14. Please update the screening argument to reflect the LANL inventory with nitrates and added organic matter that resulted in an exothermic reaction.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S15. Please modify the screening argument to address whether, in addition to "a reduction of TRU radionuclides from previous estimates", the quantities of fissile radionuclides have also been reduced.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S16. Please supplement the screening argument with information on the impacts of changes in GLOBAL:PBRINE and the PCS on brine inflow.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S17. Please supplement the screening argument with information on the impacts of changes in GLOBAL:PBRINE and the PCS on the availability of brine in the waste panels.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S18. Please supplement the screening argument with an expanded discussion of the importance of the availability of brine on the degradation of organic material. Changes that affect the availability of brine in a waste panel, such as the water balance implementation, the revised value of GLOBAL:PBRINE, and the properties of the ROMPCS and associated DRZ, will affect this FEP.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S19. Please modify the screening argument to acknowledge the reduced thermal impact of seal concrete hydration because of the elimination of additional explosion walls and the Option D monolith.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S20.The reported reason for the screening argument update is not consistent between Table SCR-1, where the update is due to new radionuclide inventory, and Section SCR-6.5.1.7.2 where the update is due to new cellulose inventory. The screening argument inSection SCR-6.5.1.7.3 refers only to the new radionuclide inventory. Please reconcile the information.

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194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S21. Please supplement the screening argument with a discussion of the impact of exothermic reactions in the waste panels. 194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S22. Please supplement the screening argument with a discussion of the impact on the PA based on a reduced concrete inventory due to DOE now not using the Option D concrete monoliths in the panel closure system. Update the analysis to include where explosion walls are or will be installed.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S23. Please update the screening argument to provide a description of the as-emplaced properties of the ROM salt now that in situ testing has been completed.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S24. Please update the screening argument to include the chemical composition of the steel bulkheads that are part of the panel closure design.194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S25. Please supplement the screening argument with information on consolidation specific to the ROM salt in the ROMPCS. Such a discussion can be found in Camphouse et al. (2012, Section 2.0. ERMS 557396).194.32 SCOPE OF PERFORMANCE ASSESSMENT 2-32-S26. The screening decision for this FEP was changed from UP (screened in) to SO-P (screened out – low probability). Please supplement the screening argument with a discussion of the chemical degradation of the steel bulkheads, which are part of the ROM salt panel closure system. Please also provide technical justification for the changed screening decision in light of the presence of the bulkheads.

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