This “Technical Evaluation Report on the Content of the U.S. Department of Energy’s Yucca Mountain License Application; Postclosure Volume: Repository Safety After Permanent Closure” (TER Postclosure Volume) presents information on the NRC staff’s review of DOE’s Safety Analysis Report (SAR), provided on June 3, 2008, as updated by DOE on February 19, 2009. The NRC staff also reviewed information DOE provided in response to NRC staff’s requests for additional information and other information that DOE provided related to the SAR.

EPRI has discovered several aspects of the U.S Department of Energy (DOE) proposed design and operation of the Yucca Mountain repository that—if implemented as described in the license application (LA)—could result in unnecessary occupational health and safety risk to workers involved with repository-related activities. This report identifies key DOE conservatisms and focuses on the occupational risk consequences of the DOE's approach to the repository design, performance assessment, and operation.

The work reported here is an investigation of the sensitivity of component temperatures in a specific storage system, including fuel cladding temperatures, in response to modeling assumptions that differ from design-basis, including age-related changes that could degrade the thermal behavior of the system. Preliminary evaluations of representative horizontal and vertical storage systems at design basis conditions provides general insight into the expected behavior of storage systems over extended periods of time.