Monte Carlo depletion analysis of UO{sub 2} and MOX fuels in a checkerboard assembly
- Lockheed Martin Idaho Technologies, Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.
One of the most favored candidate methods for disposing of weapons-grade Pu (WGPu) is to blend plutonia (PuO{sub 2}) with natural or depleted urania (UO{sub 2}), creating mixed-oxide fuel (MOC) for light water reactor (LWR) fuel pellet fabrication. To maximize the use of current LWR technology, a design goal for the MOX fuel assembly is to retain the configuration of an LWR fuel assembly. One important design requirement to meet is that the MOX fuel relative pin power not exceed the limiting envelope. The limiting relative fuel pin power in a typical Westinghouse (17 x 17) pressurized water reactor (PWR) core is 1.52. By definition, the peak relative pin power in the core is the product of the peak relative assembly power and the peak relative pin power (PRPP) in an assembly. With the nominal peak relative assembly power equal to 1.22, the MOX fuel assembly should be designed to guarantee that the PRPP is less than the limiting value 1.52/1.22 = 1.245 at beginning of cycle (BOC). Plutonium-239 has a higher thermal neutron absorption cross section than {sup 235}U, which hardens the neutron spectrum, produces larger flux gradients at the boundary between the UO{sub 2} and MOX fuel assemblies, and reduces boron worth. To reduce the impact of MOX fuel in the PWR core and compare the neutronic characteristics of reactor-grade (RG)-MOX and WG-MOX fuels, the WG-MOX fuel assemblies will be interspersed with PWR UO{sub 2} and RG-MOX fuel assemblies in a checkerboard (CHK) arrangement. The MCNP and ORIGEN2 codes and a CHK fuel assembly model (CBFAM) depletion tool are used to analyze the mixed fuel-burnup characteristics. The results of this study demonstrate that one comprehensive calculational step with the CBFAM can compute the important core physics parameters.
- OSTI ID:
- 644282
- Report Number(s):
- CONF-980606--
- Journal Information:
- Transactions of the American Nuclear Society, Journal Name: Transactions of the American Nuclear Society Vol. 78; ISSN 0003-018X; ISSN TANSAO
- Country of Publication:
- United States
- Language:
- English
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