Corrective Action Plan for Corrective Action Unit 366: Area 11 Plutonium Valley Dispersion Sites, Nevada National Security Site, Nevada
This Corrective Action Plan has been prepared for Corrective Action Unit (CAU) 366, Area 11 Plutonium Valley Dispersion Sites, in accordance with the Federal Facility Agreement and Consent Order (FFACO, 1996 as amended). CAU 366 consists of the following six Corrective Action Sites (CASs) located in Area 11 of the Nevada National Security Site: · CAS 11-08-01, Contaminated Waste Dump #1 · CAS 11-08-02, Contaminated Waste Dump #2 · CAS 11-23-01, Radioactively Contaminated Area A · CAS 11-23-02, Radioactively Contaminated Area B · CAS 11-23-03, Radioactively Contaminated Area C · CAS 11-23-04, Radioactively Contaminated Area D Site characterization activities were performed in 2011 and 2012, and the results are presented in Appendix A of the Corrective Action Decision Document (CADD) for CAU 366 (U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office [NNSA/NSO], 2012a). The following closure alternatives were recommended in the CADD: · No further action for CAS 11-23-01 · Closure in place for CASs 11-08-01, 11-08-02, 11-23-02, 11-23-03, and 11-23-04 The scope of work required to implement the recommended closure alternatives includes the following: · Non-engineered soil covers approximately 3 feet thick will be constructed at CAS 11-08-01 over contaminated waste dump (CWD) #1 and at CAS 11-08-02 over CWD #2. · FFACO use restrictions (URs) will be implemented for the areas where the total effective dose (TED) exceeds the final action level (FAL) of 25 millirems per Occasional Use Area year (mrem/OU-yr). The FAL is based on an assumption that the future use of the site includes occasional work activities and that workers will not be assigned to the area on a regular basis. A site worker under this scenario is assumed to be on site for a maximum of 80 hours per year for 5 years. The FFACO UR boundaries will encompass the areas where a worker would be exposed to 25 millirems of radioactivity per year if they are present for 80 hours per year. These boundaries will be defined as follows: – It is assumed that radiological contaminants are present at CAS 11-08-01 and CAS 11-08-02 within CWDs #1 and #2 at levels exceeding the FAL. Therefore, UR boundaries will be established around the perimeters of the soil covers that will be constructed at CWD #1 and CWD #2. A geophysical survey revealed buried metallic debris outside the fence and adjacent to CWD #1. Therefore, the UR boundary for CWD #1 will be expanded to include the mound containing buried material. – It is assumed that radiological contaminants are present at CAS 11-23-02, CAS 11-23-03, and CAS 11-23-04, within the three High Contamination Area (HCA) boundaries associated with the 11b, 11c, and 11d test areas at levels exceeding the FAL. Therefore, the UR boundaries will be established around the perimeters of the HCAs. The TED at an area of soil impacted by radiological debris outside the fence and adjacent to the 11c test area HCA exceeds the FAL of 25 mrem/OU-yr. Because the radiological impact from the debris at this location is visible on the aerial flyover radiological survey, all other areas within this isopleth of the flyover survey are conservatively also assumed to exceed the FAL. Therefore, the UR boundaries for the 11b, 11c, and 11d test areas will be expanded to include the areas within this isopleth. · The FFACO URs will all be located within the large Contamination Area (CA) that encompasses Plutonium Valley. Because access to the CA is limited and entry into the CA for post-closure inspections and maintenance would be impractical, UR warning signs will be posted along the existing CA fence. In accordance with the Soils Risk-Based Corrective Action Evaluation Process (NNSA/NSO, 2012b), an administrative UR will be implemented as a best management practice for the areas where the TED exceeds 25 millirems per Industrial Area year. This limit is based on continuous industrial use of the site and addresses exposure to industrial workers who would regularly be assigned to the work area for an entire career (250 days per year, 8 hours per day, for 25 years). Establishing an administrative UR will prevent inadvertent exposure of workers to radioactivity if a more intensive use of the site were to be considered in the future. As a precautionary measure, the administrative UR boundary will be expanded to include the areas where removable contamination is present that exceeds the criterion for a CA. This will further ensure that workers will not perform future activities within this area without being notified of the presence of site contaminants. Therefore, the administrative UR boundary will be established around the perimeters of the large CA that encompasses the site and the CAs associated with the decontamination station and hot park.
- Research Organization:
- Nevada Test Site (NTS), Mercury, NV (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- Contributing Organization:
- NSTec Environmental Restoration
- DOE Contract Number:
- DE-AC52-06NA25946
- OSTI ID:
- 1079484
- Report Number(s):
- DOE/NV-1502
- Country of Publication:
- United States
- Language:
- English
Similar Records
Corrective Action Decision Document/Closure Report for Corrective Action Unit 561: Waste Disposal Areas, Nevada National Security Site, Nevada, Revision 0
Corrective Action Decision Document/Closure Report for Corrective Action Unit 365: Baneberry Contamination Area, Nevada National Security Site, Nevada, Revision 0