Corrective Action Decision Document/Closure Report for Corrective Action Unit 367: Area 10 Sedan, Ess and Uncle Unit Craters Nevada National Security Site, Nevada, Revision 0
Corrective Action Unit 367 comprises four corrective action sites (CASs): • 10-09-03, Mud Pit • 10-45-01, U-10h Crater (Sedan) • 10-45-02, Ess Crater Site • 10-45-03, Uncle Crater Site The purpose of this Corrective Action Decision Document/Closure Report is to provide justification and documentation of the corrective actions and site closure activities implemented at CAU 367. A corrective action of closure in place with use restrictions was completed at each of the three crater CASs (10-45-01, 10-45-02, and 10-45-03); corrective actions were not required at CAS 10-09-03. In addition, a limited soil removal corrective action was conducted at the location of a potential source material release. Based on completion of these correction actions, no additional corrective action is required at CAU 367, and site closure is considered complete. Corrective action investigation (CAI) activities were performed from February 2010 through March 2011, as set forth in the Corrective Action Investigation Plan for Corrective Action Unit 367: Area 10 Sedan, Ess and Uncle Unit Craters, Nevada Test Site, Nevada. The approach for the CAI was divided into two facets: investigation of the primary release of radionuclides, and investigation of non-test or other releases (e.g., migration in washes and potential source material). Based on the proximity of the Uncle, Ess, and Sedan craters, the impact of the Sedan test on the fallout deposited from the two earlier tests, and aerial radiological surveys, the CAU 367 investigation was designed to study the releases from the three crater CASs as one combined release (primary release). Corrective Action Site 10-09-03, Mud Pit, consists of two mud pits identified at CAU 367. The mud pits are considered non-test releases or other releases and were investigated independent of the three crater CASs. The purpose of the CAI was to fulfill data needs as defined during the data quality objective (DQO) process. The CAU 367 dataset of investigation results was evaluated based on a data quality assessment. This assessment demonstrated the dataset is complete and acceptable for use in fulfilling the DQO data needs. Analytes detected during the CAI were evaluated against final action levels (FALs) established in this document. For the primary release, radiological doses exceeding the FAL of 25 millirem per year were not found to be present in the surface or shallow subsurface soil outside the default contamination boundary. However, it was assumed that radionuclides are present in subsurface media within each of the three craters (Sedan, Ess, and Uncle) due to prompt injection of radionuclides from the tests. Based on the assumption of radiological dose exceeding the FAL, corrective actions were undertaken that consisted of implementing a use restriction and posting warning signs at each crater CAS. These use restrictions were recorded in the FFACO database; the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office (NNSA/NSO) Facility Information Management System; and the NNSA/NSO CAU/CAS files. With regard to other releases, no contaminants of concern were identified at the mud pits or any of the other release locations, with one exception. Potential source material in the form of lead was found at one location. A corrective action of clean closure was implemented at this location, and verification samples indicated that no further action is necessary. Therefore, NNSA/NSO provides the following recommendations: • A Notice of Completion to NNSA/NSO is requested from the Nevada Division of Environmental Protection for closure of CAU 367. • Corrective Action Unit 367 should be promoted from Appendix III to Appendix IV of the FFACO.
- Research Organization:
- Navarro-Intera, LLC (N-I), Las Vegas, NV (United States)
- Sponsoring Organization:
- USDOE Office of Environmental Management (EM)
- DOE Contract Number:
- DEAC5209NA28091
- OSTI ID:
- 1020555
- Report Number(s):
- DOE/NV-1451; TRN: US201116%%779
- Country of Publication:
- United States
- Language:
- English
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