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Title: Corrective Action Decision Document/Corrective Action Plan for Corrective Action Unit 97: Yucca Flat/Climax Mine Nevada National Security Site, Nevada, Revision 1

Abstract

This corrective action decision document (CADD)/corrective action plan (CAP) has been prepared for Corrective Action Unit (CAU) 97, Yucca Flat/Climax Mine, Nevada National Security Site (NNSS), Nevada. The Yucca Flat/Climax Mine CAU is located in the northeastern portion of the NNSS and comprises 720 corrective action sites. A total of 747 underground nuclear detonations took place within this CAU between 1957 and 1992 and resulted in the release of radionuclides (RNs) in the subsurface in the vicinity of the test cavities. The CADD portion describes the Yucca Flat/Climax Mine CAU data-collection and modeling activities completed during the corrective action investigation (CAI) stage, presents the corrective action objectives, and describes the actions recommended to meet the objectives. The CAP portion describes the corrective action implementation plan. The CAP presents CAU regulatory boundary objectives and initial use-restriction boundaries identified and negotiated by DOE and the Nevada Division of Environmental Protection (NDEP). The CAP also presents the model evaluation process designed to build confidence that the groundwater flow and contaminant transport modeling results can be used for the regulatory decisions required for CAU closure. The UGTA strategy assumes that active remediation of subsurface RN contamination is not feasible with current technology. As amore » result, the corrective action is based on a combination of characterization and modeling studies, monitoring, and institutional controls. The strategy is implemented through a four-stage approach that comprises the following: (1) corrective action investigation plan (CAIP), (2) CAI, (3) CADD/CAP, and (4) closure report (CR) stages.« less

Authors:
 [1]
+ Show Author Affiliations
  1. Navarro, Las Vegas, NV (United States)
Publication Date:
Research Org.:
Navarro, Las Vegas, NV (United States)
Sponsoring Org.:
USDOE Office of Environmental Management (EM)
OSTI Identifier:
1410988
Report Number(s):
DOE/NV-1566-REV. 1
DOE Contract Number:
NA0002653
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; UGTA; CADD/CAP; CAU 97; Yucca Flat/Climax Mine; NNSS

Citation Formats

Farnham, Irene. Corrective Action Decision Document/Corrective Action Plan for Corrective Action Unit 97: Yucca Flat/Climax Mine Nevada National Security Site, Nevada, Revision 1. United States: N. p., 2017. Web. doi:10.2172/1410988.
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Farnham, Irene. Corrective Action Decision Document/Corrective Action Plan for Corrective Action Unit 97: Yucca Flat/Climax Mine Nevada National Security Site, Nevada, Revision 1. United States. doi:10.2172/1410988.
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Farnham, Irene. Tue . "Corrective Action Decision Document/Corrective Action Plan for Corrective Action Unit 97: Yucca Flat/Climax Mine Nevada National Security Site, Nevada, Revision 1". United States. doi:10.2172/1410988. https://www.osti.gov/servlets/purl/1410988.
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@article{osti_1410988,
title = {Corrective Action Decision Document/Corrective Action Plan for Corrective Action Unit 97: Yucca Flat/Climax Mine Nevada National Security Site, Nevada, Revision 1},
author = {Farnham, Irene},
abstractNote = {This corrective action decision document (CADD)/corrective action plan (CAP) has been prepared for Corrective Action Unit (CAU) 97, Yucca Flat/Climax Mine, Nevada National Security Site (NNSS), Nevada. The Yucca Flat/Climax Mine CAU is located in the northeastern portion of the NNSS and comprises 720 corrective action sites. A total of 747 underground nuclear detonations took place within this CAU between 1957 and 1992 and resulted in the release of radionuclides (RNs) in the subsurface in the vicinity of the test cavities. The CADD portion describes the Yucca Flat/Climax Mine CAU data-collection and modeling activities completed during the corrective action investigation (CAI) stage, presents the corrective action objectives, and describes the actions recommended to meet the objectives. The CAP portion describes the corrective action implementation plan. The CAP presents CAU regulatory boundary objectives and initial use-restriction boundaries identified and negotiated by DOE and the Nevada Division of Environmental Protection (NDEP). The CAP also presents the model evaluation process designed to build confidence that the groundwater flow and contaminant transport modeling results can be used for the regulatory decisions required for CAU closure. The UGTA strategy assumes that active remediation of subsurface RN contamination is not feasible with current technology. As a result, the corrective action is based on a combination of characterization and modeling studies, monitoring, and institutional controls. The strategy is implemented through a four-stage approach that comprises the following: (1) corrective action investigation plan (CAIP), (2) CAI, (3) CADD/CAP, and (4) closure report (CR) stages.},
doi = {10.2172/1410988},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Aug 01 00:00:00 EDT 2017},
month = {Tue Aug 01 00:00:00 EDT 2017}
}
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DOI:  10.2172/1410988
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  • ;
    This Corrective Action Investigation Plan contains the U.S. Department of Energy, Nevada Operations Office's (DOE/NV's) approach to collect the data necessary to evaluate Corrective Action Alternatives (CAAs) appropriate for the closure of Corrective Action Unit (CAU) 97 under the Federal Facility Agreement and Consent Order (FFACO). Corrective Action Unit 97, collectively known as the Yucca Flat/Climax Mine CAU, consists of 720 Corrective Action Sites (CASs). The Yucca Flat/Climax Mine CAU extends over several areas of the NTS and constitutes one of several areas used for underground nuclear testing in the past. The nuclear tests resulted in groundwater contamination in themore » vicinity as well as downgradient of the underground test areas. Based on site history, the Yucca Flat underground nuclear tests were conducted in alluvial, volcanic, and carbonate rocks; whereas, the Climax Mine tests were conducted in an igneous intrusion located in northern Yucca Flat. Particle-tracking simulations performed during the regional evaluation indicate that the local Climax Mine groundwater flow system merges into the much larger Yucca Flat groundwater flow systems during the 1,000-year time period of interest. Addressing these two areas jointly and simultaneously investigating them as a combined CAU has been determined the best way to proceed with corrective action investigation (CAI) activities. The purpose and scope of the CAI includes characterization activities and model development conducted in five major sequential steps designed to be consistent with FFACO Underground Test Area Project's strategy to predict the location of the contaminant boundary, develop and implement a corrective action, and close each CAU. The results of this field investigation will support a defensible evaluation of CAAs in the subsequent corrective action decision document.« less

  • The Underground Test Area (UGTA) Corrective Action Unit (CAU) 97, Yucca Flat/Climax Mine, in the northeast part of the Nevada National Security Site (NNSS) requires environmental corrective action activities to assess contamination resulting from underground nuclear testing. These activities are necessary to comply with the UGTA corrective action strategy (referred to as the UGTA strategy). The corrective action investigation phase of the UGTA strategy requires the development of groundwater flow and contaminant transport models whose purpose is to identify the lateral and vertical extent of contaminant migration over the next 1,000 years. In particular, the goal is to calculate themore » contaminant boundary, which is defined as a probabilistic model-forecast perimeter and a lower hydrostratigraphic unit (HSU) boundary that delineate the possible extent of radionuclide-contaminated groundwater from underground nuclear testing. Because of structural uncertainty in the contaminant boundary, a range of potential contaminant boundaries was forecast, resulting in an ensemble of contaminant boundaries. The contaminant boundary extent is determined by the volume of groundwater that has at least a 5 percent chance of exceeding the radiological standards of the Safe Drinking Water Act (SDWA) (CFR, 2012).« less

  • ;
    The peer review team commends the Navarro-Intera, LLC (N-I), team for its efforts in using limited data to model the fate of radionuclides in groundwater at Yucca Flat. Recognizing the key uncertainties and related recommendations discussed in Section 6.0 of this report, the peer review team has concluded that U.S. Department of Energy (DOE) is ready for a transition to model evaluation studies in the corrective action decision document (CADD)/corrective action plan (CAP) stage. The DOE, National Nuclear Security Administration Nevada Field Office (NNSA/NFO) clarified the charge to the peer review team in a letter dated October 9, 2014, frommore » Bill R. Wilborn, NNSA/NFO Underground Test Area (UGTA) Activity Lead, to Sam J. Marutzky, N-I UGTA Project Manager: “The model and supporting information should be sufficiently complete that the key uncertainties can be adequately identified such that they can be addressed by appropriate model evaluation studies. The model evaluation studies may include data collection and model refinements conducted during the CADD/CAP stage. One major input to identifying ‘key uncertainties’ is the detailed peer review provided by independent qualified peers.” The key uncertainties that the peer review team recognized and potential concerns associated with each are outlined in Section 6.0, along with recommendations corresponding to each uncertainty. The uncertainties, concerns, and recommendations are summarized in Table ES-1. The number associated with each concern refers to the section in this report where the concern is discussed in detail.« less

  • CAU 104 comprises the following corrective action sites (CASs): • 07-23-03, Atmospheric Test Site T-7C • 07-23-04, Atmospheric Test Site T7-1 • 07-23-05, Atmospheric Test Site • 07-23-06, Atmospheric Test Site T7-5a • 07-23-07, Atmospheric Test Site - Dog (T-S) • 07-23-08, Atmospheric Test Site - Baker (T-S) • 07-23-09, Atmospheric Test Site - Charlie (T-S) • 07-23-10, Atmospheric Test Site - Dixie • 07-23-11, Atmospheric Test Site - Dixie • 07-23-12, Atmospheric Test Site - Charlie (Bus) • 07-23-13, Atmospheric Test Site - Baker (Buster) • 07-23-14, Atmospheric Test Site - Ruth • 07-23-15, Atmospheric Test Site T7-4 •more » 07-23-16, Atmospheric Test Site B7-b • 07-23-17, Atmospheric Test Site - Climax These 15 CASs include releases from 30 atmospheric tests conducted in the approximately 1 square mile of CAU 104. Because releases associated with the CASs included in this CAU overlap and are not separate and distinguishable, these CASs are addressed jointly at the CAU level. The purpose of this CADD/CAP is to evaluate potential corrective action alternatives (CAAs), provide the rationale for the selection of recommended CAAs, and provide the plan for implementation of the recommended CAA for CAU 104. Corrective action investigation (CAI) activities were performed from October 4, 2011, through May 3, 2012, as set forth in the CAU 104 Corrective Action Investigation Plan.« less

  • This CADD/CAP follows the Corrective Action Investigation (CAI) stage, which results in development of a set of contaminant boundary forecasts produced from groundwater flow and contaminant transport modeling of the Frenchman Flat CAU. The Frenchman Flat CAU is located in the southeastern portion of the NNSS and comprises 10 underground nuclear tests. The tests were conducted between 1965 and 1971 and resulted in the release of radionuclides in the subsurface in the vicinity of the test cavities. Two important aspects of the corrective action process are presented within this CADD/CAP. The CADD portion describes the results of the Frenchman Flatmore » CAU data-collection and modeling activities completed during the CAI stage. The corrective action objectives and the actions recommended to meet the objectives are also described. The CAP portion describes the corrective action implementation plan. The CAP begins with the presentation of CAU regulatory boundary objectives and initial use restriction boundaries that are identified and negotiated by NNSA/NSO and the Nevada Division of Environmental Protection (NDEP). The CAP also presents the model evaluation process designed to build confidence that the flow and contaminant transport modeling results can be used for the regulatory decisions required for CAU closure. The first two stages of the strategy have been completed for the Frenchman Flat CAU. A value of information analysis and a CAIP were developed during the CAIP stage. During the CAI stage, a CAIP addendum was developed, and the activities proposed in the CAIP and addendum were completed. These activities included hydrogeologic investigation of the underground testing areas, aquifer testing, isotopic and geochemistry-based investigations, and integrated geophysical investigations. After these investigations, a groundwater flow and contaminant transport model was developed to forecast contaminant boundaries that enclose areas potentially exceeding the Safe Drinking Water Act radiological standards at any time within 1,000 years. An external peer review of the groundwater flow and contaminant transport model was completed, and the model was accepted by NDEP to allow advancement to the CADD/CAP stage. The CADD/CAP stage focuses on model evaluation to ensure that existing models provide adequate guidance for the regulatory decisions regarding monitoring and institutional controls. Data-collection activities are identified and implemented to address key uncertainties in the flow and contaminant transport models. During the CR stage, final use restriction boundaries and CAU regulatory boundaries are negotiated and established; a long-term closure monitoring program is developed and implemented; and the approaches and policies for institutional controls are initiated. The model evaluation process described in this plan consists of an iterative series of five steps designed to build confidence in the site conceptual model and model forecasts. These steps are designed to identify data-collection activities (Step 1), document the data-collection activities in the 0CADD/CAP (Step 2), and perform the activities (Step 3). The new data are then assessed; the model is refined, if necessary; the modeling results are evaluated; and a model evaluation report is prepared (Step 4). The assessments are made by the modeling team and presented to the pre-emptive review committee. The decision is made by the modeling team with the assistance of the pre-emptive review committee and concurrence of NNSA/NSO to continue data and model assessment/refinement, recommend additional data collection, or recommend advancing to the CR stage. A recommendation to advance to the CR stage is based on whether the model is considered to be sufficiently reliable for designing a monitoring system and developing effective institutional controls. The decision to advance to the CR stage or to return to step 1 of the process is then made by NDEP (Step 5).« less