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Fuel cycle analysis of a fast breeder reactor. P. Vertes, KFKI Atomic Energy Research Institute, Budapest, Hungary. The model reactor- BN800, sodium cooled. 1 - zone of core with low Pu content (24.4%) 2 - zone of core with median Pu content (27.3%)
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Fuel cycle analysis of a fast breeder reactor P. Vertes, KFKI Atomic Energy Research Institute, Budapest, Hungary
The model reactor- BN800, sodium cooled 1 - zone of core with low Pu content (24.4%) 2 - zone of core with median Pu content (27.3%) 3 - zone of core with high Pu content (32.9%) 4 - radial breeding blanket 5 - axial breeding blanket 6 - reflector
Main operational data of the reactor and strategy of calculations Heavy metal masses (fixed): Core: 11228.5 kg, axial blanket: 9351.8 kg, radial blanket: 25682.2 kg Power: 2100MWth, burnup cycle: 165 days 1st load: Pu+MA from spent PWR fuels and Th as breeding materials After each cycle all bred uran are extracted and placed into the core in such extent as criticality reached; if the bred fissionable is not enough then Pu from PWR is taken Tool for calculation: NOTRADAT system (NJOY, TRANSX, DANTSYS, TIBSO) Each cycle is consisted of 10 burnup steps. The keff only after the last step should be less than 1
The breeding-burning cycles The 1st loading of the core contains 31w% Pu+MA and 69w% Th; the blankets are exclusively from Th In the next cycles there are two version: • a new set of spent fuel Pu+MA placed in the core • the Pu+MA burned in previous cycles are left in required extent
. Mass changes during cycles when Pu+MA is new before each cycle (option 1)
Mass changes in version 1. • decrease in amounts of transurans:1868 kg • make up Th: 11212 kg • Bred minus burned U-233 during 14 cycles: 2016 kg • Bred minus burned U-235 during 14 cycles: 94.2 After 14 cycles no more spent fuel Pu+MA required for sustaining the operation of reactor
Mass changes during cycles when Pu+MA is continuously burning
Mass changes in version 2. • decrease in amounts of transurans:1934 kg • make up Th: 13416 kg • Bred minus burned U-233 during 17 cycles: 2023 kg • Bred minus burned U-235 during 17 cycles: 112 kg After 17 cycles no more spent fuel Pu+MA required for sustaining the operation of reactor
Remarks This contribution is a part of a series of investigations concerning the fuel cycle operation of fast breeders Our principles are: • Only spent fuel materials as fissionable must be used • The UREX reprocessing method is recommended • Breeding materials are Th or/and depleted U Next step: calculation kinetic parameters