A Study on the Characteristics of the Radiation Source Terms of Spent Fuel and Various Non-Fuel Hardware for Shielding Applications

Review of SCALE Validations Applicable to Spent Nuclear Fuel Shielding Calculations

“…Only nuclides important to radiation source terms and dose rates are discussed in this report. These radionuclides have been identified in previous studies based on cask shielding calculations [11,12,13]. The cooling times analyzed in those studies are 1 to 40 years, 100 years, and Comparison of code predictions to experimental measurements for high quality experimental data [14] for one PWR UO2 fuel sample shows that SCALE nuclide concentration predictions are in good agreement with the measured values for most of the measured nuclides and these predictions are similar to nuclide concentrations calculated with other depletion codes.…”

Updated Recommendations Related to Spent Fuel Transport and Dry Storage Shielding Analyses

“…The information consolidated in the report includes publicly available light water reactor (LWR) fuel assembly design data dated 1992 or older. ORNL/SPR-2021/2373 [16] describes a study on the characteristics of SNF and NFH radiation source terms for shielding applications. A parametric study in that report extended the range of depletion parameters previously analyzed in NUREG/CR-6802 for the treatment of PWR and BWR fuel with increased enrichment and higher burnup.…”

“…The guidance in NUREG-2215 and NUREG-2216 indicates that bounding source terms should be used in shielding analyses and that the fuel assembly minimum initial enrichment, maximum burnup, and minimum cooling time are more appropriate for use as loading controls and limits. Previous parametric studies [9,10,16] have clearly shown that SNF neutron source strength-and consequently the neutron and secondary gamma dose ratessignificantly increase with decreasing fuel enrichments at a fixed burnup. An increase of the fuel initial enrichment causes an increase of the 235 U absorption rate, a decrease of the absorption rates of other nuclides, a reduction of the thermal neutron flux, and hardening of the neutron spectrum.…”

“…This report provides updated recommendations relevant to current shielding designs and analyses, which are primarily based on a series of ORNL research studies sponsored by the NRC. These research studies are documented in sponsor reports [13,14,15,16,17,18] that are publicly available from the DOE Office of Scientific and Technical Information (OSTI.GOV). More justification for updated shielding recommendations is provided in Section 1.1.…”

Review of Experimental Data for Validating Computer Codes Used in Shielding Calculations for Spent Fuel Storage and Transportation Systems

“…The most important radionuclides in SNF with respect to radiation source terms have been identified in previous work based on cask shielding calculations [13,14,15]. The cooling times analyzed in those studies are 1 to 40 years, 100 years, and 10,000 years.…”