Reactivity effects of fission product decay in PWRs
The purpose of the work reported in this paper is to analyze the effects of fission product chains with radioactive decay on the reactivity in pressurized water reactor (PWR) cores, calculating their accumulation and absorption rates along fuel burnup at continuous operation and after shutdown periods extending from 1 day to a few months. The authors PWR version of the WIMS-D4 code is first used to obtain the individual number densities, absorption rates, and averaged cross sections for every nuclide of the fission product chains with significant decay rates, as a function of fuel burnup at continuous irradiation. Next, by an auxiliary ad hoc code, these data, have been processed together with the required one for fissile nuclides and boron, also taken from WIMS at each burnup step, to calculate the average or effective values relevant for the analysis and the decay and change in overall absorption after several shutdown times. (1) The reactivity effect of fission product decay changes significantly with the shutdown time. The maximum absorption increase by decay is reached in /approx/ 10 days' shutdown. (2) The dependence with fuel type, enrichment, and burnup is slight, but the change with previous power density is nearly linear, which might be significant after coast-down in previous cycles. (3) For long shutdown periods, the overall reactivity effect of decay in the three fission product chains considered is much less than if only the samarium peak due to /sup 149/Nd is considered.
- OSTI ID:
- 5942383
- Report Number(s):
- CONF-881011-
- Journal Information:
- Trans. Am. Nucl. Soc.; (United States), Vol. 57; Conference: Joint meeting of the European Nuclear Society and the American Nuclear Society, Washington, DC, USA, 30 Oct - 4 Nov 1988
- Country of Publication:
- United States
- Language:
- English
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TRIGA MARK-II source term
PRESSURIZED WATER REACTOR (PWR) PROJECT TECHNICAL PROGRESS REPORT FOR THE PERIOD OCTOBER 24, 1960 TO DECEMBER 23, 1960
Related Subjects
FISSION PRODUCTS
DECAY
PWR TYPE REACTORS
REACTOR KINETICS
ABSORPTION
BORON
BURNUP
FISSILE MATERIALS
IRRADIATION
NEODYMIUM
REACTIVITY
REACTOR CORES
REACTOR OPERATION
REACTOR SHUTDOWN
SAMARIUM
W CODES
COMPUTER CODES
ELEMENTS
FISSIONABLE MATERIALS
ISOTOPES
KINETICS
MATERIALS
METALS
OPERATION
RADIOACTIVE MATERIALS
RARE EARTHS
REACTOR COMPONENTS
REACTORS
SEMIMETALS
SHUTDOWNS
WATER COOLED REACTORS
WATER MODERATED REACTORS
210200* - Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled