Validation Study for Crediting Chlorine in Criticality Analyses for Spent Nuclear Fuel Disposition

Conference · Sun Sep 13 00:00:00 EDT 2015

OSTI ID:1215581

Sobes, Vladimir ^[1]; Scaglione, John M. ^[1]; Wagner, John C. ^[1]; Dunn, Michael E. ^[1]

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1. UT-Battelle LLC/ORNL, Oak Ridge, TN (United States)

Spent nuclear fuel (SNF) management practices in the United States rely on dry storage systems that include both canister- and cask-based systems. The United States Department of Energy Used Fuel Disposition Campaign is examining the feasibility of direct disposal of dual-purpose (storage and transportation) canisters (DPCs) in a geological repository. One of the major technical challenges for direct disposal is the ability to demonstrate the subcriticality of the DPCs loaded with SNF for the repository performance period (e.g., 10,000 years or more) as the DPCs may undergo degradation over time. Specifically, groundwater ingress into the DPC (i.e., flooding) could allow the system to achieve criticality in scenarios where the neutron absorber plates in the DPC basket have degraded. However, as was shown by Banerjee et al., some aqueous species in the groundwater provide noticeable reactivity reduction for these systems. For certain amounts of particular aqueous species (e.g., chlorine, lithium) in the groundwater, subcriticality can be demonstrated even for DPCs with complete degradation of the neutron absorber plates or a degraded fuel basket configuration. It has been demonstrated that chlorine is the leading impurity, as indicated by significant neutron absorption in the water that is available in reasonable quantities for the deep geological repository media under consideration. This paper presents the results of an investigation of the available integral experiments worldwide that could be used to validate DPC disposal criticality evaluations, including credit for chlorine. Due to the small number of applicable critical configurations, validation through traditional trending analysis was not possible. The bias in the eigenvalue of the application systems due only to the chlorine was calculated using TSURFER analysis and found to be on the order of 100 percent mille (1 pcm = 10^-5 k_eff). This study investigated the design of a series of critical configurations with varying amounts of chlorine to address validation gaps. Such integral experiments would support the crediting of the chlorine neutron-absorption properties in groundwater and the demonstration of subcriticality for DPCs in deep geologic repositories with sufficient chlorine availability.

• Research Organization: UT-Battelle LLC/ORNL, Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1215581
• Resource Relation: Conference: 2015 International Conference on Nuclear Criticality (ICNC 2015), Development of Standards and Assessment Methodology-II , Charlotte, NC (United States), 13-17 Sep 2015; Related Information: https://www.ans.org/meetings/view-191/
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
Nuclear Criticality Safety Program (NCSP)
Dual-Purpose Canisters (DPCs)
TSURFER Analysis
Chlorine
Validation
Groundwater
Disposition
Heavy Metal (MTHM)
Pressurized Water Reactor (PWR)
KENO
TSUNAMI-3D
SCALE 6.1 Code Package
SAMINT