Measurement of radiolytic hydrogen generation and impact of drying treatments on reactor exposed and surrogate aluminum materials
- Savannah River Nuclear Solutions (SRNS), Aiken, SC (United States); Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
Technical challenges associated with dry storage of Aluminum-clad Spent Nuclear Fuel (ASNF) include a need to better understand the potential extent of gaseous molecular hydrogen (H2) production through radiolytic degradation of the aluminum (oxy)hydroxide films present on ASNF. The characterization of radiolytic gas generation from ASNF (oxy)hydroxide layers has been identified as a key knowledge gap which poses a technical challenge to the long-term storage of ASNF. Task 2 of the action plan for the extended (>50 years) dry storage of ASNF addresses this gap. Previous radiolysis studies performed under Task 2 established baseline estimates of H2 generation rates from the attendant hydrated oxides. The results confirmed that net radiolytic H2 production has a dependency on absorbed gamma dose, as well as relative humidity and cover gas composition (air, nitrogen, and argon). Further experiments revealed that the physisorbed water on the samples may significantly impact the radiolytic H2 yield. This phenomenon complicates the determination of H2 generation rates for hydrated oxides, which may lead to inaccurate modeling predictions of the long-term H2 yields in sealed storage systems containing ASNF, particularly when compared to spent fuel casks which have undergone some drying process intended to remove physically- and chemically-bound water. This report describes the testing methods utilized and the hydrogen generation results obtained in an investigation of the effects of gamma irradiation on aluminum materials for a variety of (oxy)hydroxide surface compositions and drying conditions. The testing methods included small-area aluminum material testing in ampules, and large-area aluminum material testing in steel vessels. Test material preparation, irradiation, and radiolytic H2 measurement methods are summarized. The measured H2 concentrations, which reflect the variable initial hydrated inventory and drying treatments, are compared to one another as well as to previously published data, to identify the primary factors affecting radiolytic H2 generation rates and potential equilibrium H2 concentrations.
- Research Organization:
- Savannah River Nuclear Solutions (SRNS), Aiken, SC (United States); Savannah River National Laboratory (SRNL), Aiken, SC (United States)
- Sponsoring Organization:
- USDOE Office of Environmental Management (EM)
- DOE Contract Number:
- 89303321CEM000080
- OSTI ID:
- 1838351
- Report Number(s):
- SRNL-STI-2021-00625; TRN: US2302619
- Country of Publication:
- United States
- Language:
- English
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