Corrective Action Decision Document/Closure Report for Corrective Action Unit 375: Area 30 Buggy Unit Craters, Nevada National Security Site, Nevada, Revision 0

Abstract

Corrective Action Unit 375 comprises three corrective action sites (CASs): (1) 25-23-22, Contaminated Soils Site; (2) 25-34-06, Test Cell A Bunker; and (3) 30-45-01, U-30a, b, c, d, e Craters. The purpose of this CADD/CR is to provide justification and documentation supporting the recommendation that no further corrective action is needed for CAU 375 based on the implementation of corrective action of closure in place with administrative controls at CAS 25-23-22, no further action at CAS 25-34-06, and closure in place with administrative controls and removal of potential source material (PSM) at CAS 30-45-01. Corrective action investigation (CAI) activities were performed from July 28, 2010, through April 4, 2011, as set forth in the Corrective Action Investigation Plan for Corrective Action Unit 375: Area 30 Buggy Unit Craters. The approach for the CAI was divided into two facets: investigation of the primary release of radionuclides, and investigation of other releases (migration in washes and chemical releases). The purpose of the CAI was to fulfill data needs as defined during the data quality objective (DQO) process. The CAU 375 dataset of investigation results was evaluated based on the data quality assessment. This assessment demonstrated the dataset is acceptable for use in fulfilling the DQO data needs. Investigation results were evaluated against final action levels (FALs) established in this document. A radiological dose FAL of 25 millirem per year was established based on the Remote Work Area exposure scenario (336 hours of annual exposure). Radiological doses exceeding the FAL were assumed to be present within the default contamination boundaries at CASs 25-23-22 and 30-45-01. No contaminants were identified at CAS 25-34-06, and no corrective action is necessary. Potential source material in the form of lead plate, lead-acid batteries, and oil within an abandoned transformer were identified at CAS 30-45-01, and corrective actions were undertaken that consisted of removing the PSM. Use restrictions and warning signs were implemented for the remaining radiological contamination at CASs 25-23-22 and 30-45-01. 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. Therefore, NNSA/NSO provides the following recommendations: (1) No further corrective actions are necessary for CAU 375; (2) A Notice of Completion to NNSA/NSO is requested from the Nevada Division of Environmental Protection for closure of CAU 375; and (3) Move CAU 375 from Appendix III to Appendix IV of the FFACO.