Decay heat and gamma dose-rate prediction capability in spent LWR fuel

Technical Report · Sun Aug 01 04:00:00 EDT 1982

DOI:https://doi.org/10.2172/6949675· OSTI ID:6949675

Neely, G J; Schmittroth, F

The ORIGEN2 code was established as a valid means to predict decay heat from LWR spent fuel assemblies for decay times up to 10,000 year. Calculational uncertainties ranged from 8.6% to a maximum of 16% at 2.5 years and 300 years cooling time, respectively. The calculational uncertainties at 2.5 years cooling time are supported by experiment. Major sources of uncertainty at the 2.5 year cooling time were identifed as irradiation history (5.7%) and nuclear data together with calculational methods (6.3%). The QAD shielding code was established as a valid means to predict interior and exterior gamma dose rates of spent LWR fuel assemblies. A calculational/measurement comparison was done on two assemblies with different irradiation histories and supports a 35% calculational uncertainty at the 1.8 and 3.0 year decay times studied. Uncertainties at longer times are expected to increase, but not significantly, due to an increased contribution from the actinides whose inventories are assigned a higher uncertainty. The uncertainty in decay heat rises to a maximum of 16% due to actinide uncertainties. A previous study was made of the neutron emission rate from a typical Turkey Point Unit 3, Region 4 spent fuel assembly at 5 years decay time. A conservative estimate of the neutron dose rate at the assembly surface was less than 0.5 rem/hr.

• Research Organization: Hanford Engineering Development Lab., Richland, WA (USA)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC06-76FF02170
• OSTI ID: 6949675
• Report Number(s): HEDL-TC-1787; ON: DE82021027
• Country of Publication: United States
• Language: English

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