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U.S. Department of Energy
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Survey of vessel fluence reduction techniques. Final report

Technical Report ·
OSTI ID:6428442

Strategies are examined for slowing PWR pressure vessel embrittlement by reducing the incident fast flux to the vessel through fuel management and core periphery modifications. Such strategies can help to mitigate the consequences of pressurized thermal shock (PTS), a current licensing concern. Design quality analytical techniques were used to calculate power and flux distributions; in contrast to previous work in this area, spatial power redistribution and isotopic depletion effects were explicitly calculated. For most operating PWRs, a factor of 2 reduction in fast flux to the reactor vessel critical welds can be achieved with little or no penalty in power peaking (3% or less). This can be accomplished with low leakage fuel management which places twice-burned fuel in selected peripheral locations near the critical welds. To achieve higher reduction factors, fast neutron reflecting materials must be used in conjunction with low leakage fuel management. In general, a factor of 3 reduction in fast flux is a practical upper limit to what can be reasonably achieved without significant thermal margin degradation.

Research Organization:
Combustion Engineering, Inc., Windsor, CT (USA). Power Systems Group
OSTI ID:
6428442
Report Number(s):
EPRI-NP-3664; ON: TI85920006
Country of Publication:
United States
Language:
English