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Title 40 CFR Part 191
Subparts B and C
Compliance Recertification
for the
Waste Isolation Pilot Plant

Executive Summary

United States Department of Energy
Waste Isolation Pilot Plant

Carlsbad Field Office
Carlsbad, New Mexico


Executive Summary

Table of Contents


EXECSUM-1.0 Overview.. EXECSUM-1

EXECSUM-1.1 Contents of the CRA-2009. EXECSUM-2

EXECSUM-1.2 Changes Since the CRA-2004. EXECSUM-2

EXECSUM-1.3 Results. EXECSUM-3



List of Figures

Figure EXECSUM-1.      Overall Mean Total Releases for the CCA, CRA-2004, and CRA-2009. EXECSUM-4



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Acronyms and Abbreviations

CCA                Compliance Certification Application

CCDF              complementary cumulative distribution functions

CFR                 Code of Federal Regulations

CRA                Compliance Recertification Application

DOE                U.S. Department of Energy

EPA                 U.S. Environmental Protection Agency

FEPs                features, events, and processes

LANL              Los Alamos National Laboratory

LWA               Land Withdrawal Act

MgO                magnesium oxide

PA                   performance assessment

PABC              Performance Assessment Baseline Calculation

T fields             transmissivity fields

TRU                 transuranic

RH                   Remote-Handled

WIPP               Waste Isolation Pilot Plant

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EXECSUM-1.0  Overview

The Waste Isolation Pilot Plant (WIPP), located near Carlsbad, New Mexico, is a deep geologic repository for the disposal of transuranic (TRU) wastes generated by U.S. defense activities.  The WIPP Land Withdrawal Act (LWA) (Pub. L. 102-579, 106 stat. 4777, as amended by Pub. L. 104-201, 110 stat. 2422) requires the U.S. Environmental Protection Agency (EPA) to certify the WIPP’s compliance with the long-term disposal regulations of 40 CFR Part 191 Subparts B and C prior to the commencement of disposal operations.  To comply with this requirement, the U.S. Department of Energy (DOE) submitted the Compliance Certification Application (CCA) in October 1996 demonstrating compliance with the disposal standards and the criteria for compliance established at 40 CFR Part 194.  The CCA demonstrated how the geological, hydrological, physical, chemical, and environmental characteristics of the site, along with engineered features of the facility, would safely contain radioactive waste for the 10,000-year regulatory time period. After a thorough review of the CCA, the EPA certified WIPP’s compliance with these regulations in May 1998, paving the way for waste disposal operations which began on March 26, 1999.

The WIPP LWA also requires the DOE to submit documentation of WIPP’s continued compliance with the disposal regulations to the EPA not later than five years after initial receipt of TRU waste for disposal at the repository, and every five years thereafter until the decommissioning of the facility is completed.  This periodic documentation of continued compliance is referred to as “recertification.”  The DOE has completed one recertification cycle.  The first Compliance Recertification Application (CRA-2004) was submitted to the EPA on March 26, 2004.  After a thorough review of the CRA-2004, the EPA recertified the WIPP’s compliance on March 29, 2006.  The second five-year recertification cycle ends on March 26, 2009.  As with the CRA-2004, the CRA-2009 is being submitted to the EPA in accordance with the provisions of the LWA and demonstrates that the WIPP continues to be in compliance with the applicable radioactive waste disposal standards.

According to the WIPP Certification Criteria at 40 CFR § 194.15, recertification applications must include any information that is new or different from information contained in the most recent compliance application.  Therefore, the DOE must review any new information that relates to the WIPP’s certification basis and include the new information in each CRA.  The central message of this CRA-2009 is that no significant changes have taken place since the CRA‑2004 was submitted in March 2004.  While there are minor changes documented and analyzed in the following recertification application, none compromise compliance with the radioactive waste disposal standards.  The second five-year recertification cycle ends on March 26, 2009. As with the CRA-2004, the CRA-2009 is being submitted to the EPA in accordance with the provisions of the LWA and demonstrates that the WIPP continues to be in compliance with the applicable radioactive waste disposal standards.  Continuing scientific studies and analyses have led to the conclusion that the WIPP repository is operating and performing as expected.  This conclusion is underpinned by the fact that the results and analyses based on well-established probabilistic modeling tools show that the repository will not adversely impact public health and the environment during the required regulatory period.

EXECSUM-1.1  Contents of the CRA-2009

The CRA-2009 has been developed in accordance with the EPA’s Certification Criteria found at Part 194.  The Criteria allow unchanged information contained in previous applications to be referenced, rather than repeated in recertification applications.  Topics addressed in the CRA‑2009 include, but are not limited to, the following:

·        Natural and engineered features of the disposal system, including geology, geophysics, and hydrogeology of the repository and its environs, as well as the geochemistry of interactions between the disposal system and the wastes placed in it

·        Information concerning the inventory of TRU waste emplaced in the repository, stored at DOE sites, and the waste expected to be generated at those sites and shipped to the WIPP in the future

·        Updated WIPP-relevant features, events, and processes (FEPs) based on data and information acquired since the most recent CRA.  FEPs are screened using specific criteria to determine what phenomena and components of the disposal system can and should be dealt with in PA calculations.

·        Assessments of the disposal system’s long-term performance, including the input parameters and models used in those assessments

·        Individual and groundwater protection standards and the DOE’s analyses demonstrating that the WIPP meets or exceeds those standards and will continue to do so

·        Assurance requirements, including active and passive institutional controls, monitoring, and the effects of natural resource extraction.

EXECSUM-1.2  Changes Since the CRA-2004

This application incorporates information about, and assessments of, changes proposed by the DOE and approved by the EPA or requested by the EPA since the CRA-2004.  In addition, some changes were driven by the availability of new data. These changes may involve different aspects of the physical repository and its components, as well as changes to the predictive tools used to demonstrate compliance.  These changes include

·        Inventory:  The inventory included in the CRA-2004 was updated during the CRA-2004 Performance Assessment Baseline Calculation (PABC) in response to comments from the EPA.  The inventory used in the CRA-2009 PA is the same as the PABC inventory, which is slightly different from that used in the CRA-2004.  Section 24 of this application contains details on the inventory.

·        Remote-Handled (RH) TRU Waste:  WIPP began accepting RH-TRU waste in January 2007.  The impact to the performance of the repository for this waste is assessed in the current performance assessment (PA) as was done in all previous PAs.  Information related to the RH-TRU certification process is found in Sections 8 and 21.

·        CRA-2004 PABC Parameters:  Changes to the CRA-2004 PA were made during the recertification process as part of the CRA-2004 PABC.  The CRA-2004 PABC included changes in gas generation modeling, PA parameter changes, new Culebra transmissivity fields (T fields), and revisions to the calculations of spallings releases during drilling.

·        CRA-2009 PA Updates: Changes to PA since the CRA-2004 PABC include parameter updates, code improvements, and corrections.  Upgrades were also made to the computational platform used to execute the CRA-2009 PA.  These changes are described in detail in Appendix PA-2009, Section PA-2.1.1.

·        Engineered Barrier:  The DOE obtained approval from the EPA to reduce the excess factor for the WIPP’s engineered barrier (magnesium oxide – MgO chemical buffer) from 1.67 to 1.2. Additionally, the supplier for the engineered barrier has changed from that used during the CRA-2004.  See Section 44 of this application for additional information. These changes are detailed in Appendix MgO-2009.

·        Peer Review:  Documentation of WIPP peer reviews pertaining to RH-TRU waste visual examination data verification and sealed sources at Los Alamos National Laboratory (LANL) are presented in the CRA-2009.  These peer reviews are detailed in Section 27.

EXECSUM-1.3  Results

Past PA results included in the previous certification applications (and two previous EPA-requested PAs) have all demonstrated compliance with the release limits of 40 CFR Part 191.  Based on these PA results and other information contained in the compliance applications, the EPA has continued to certify the WIPP’s compliance with the long-term disposal regulations.  Similar to the CRA-2004, the CRA-2009 assesses the combined effect of any new changes on the performance of the disposal system.  As with the results of past PAs, the combined effects of changes analyzed in this CRA do not adversely impact performance or compliance; the predicted releases from the repository remain well below the limits specified in Part 191 Subpart B.  Continued compliance with the assurance requirements of the standards and the criteria is also demonstrated by CRA-2009.

The results of the CRA-2009 PA demonstrate that the repository continues to comply with the disposal standards.  The results demonstrate a greater-than-95% level of statistical confidence that the overall mean of the population of complementary cumulative distribution functions (CCDFs) is in compliance with the containment requirements of 40 CFR § 191.13.  The overall mean CCDFs of the CCA, CRA-2004, and CRA-2009 are shown in Figure EXECSUM-1 and illustrate the wide margin of compliance of the predicted releases with respect to the release limits.

Similarly, compliance analyses performed on the undisturbed repository result in a single postulated release whose value is significantly smaller than even the very small release estimated by the same analyses in the CCA.  Taken together, the CCA, the CRA-2004, and the CRA-2009 compliance analyses demonstrate that the WIPP continues to comply with the individual and groundwater protection standards in Part 191 Subparts B and C.

Figure EXECSUM-1.    Overall Mean Total Releases for the CCA, CRA-2004, and CRA‑2009