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17 th AER Symposium Yalta, 24-28 September, 2007

USE OF VVER SPENT FUELS IN A THORIUM FAST BREEDER P. Vértes, KFKI Atomic Energy Research Institute, Budapest, Hungary. 17 th AER Symposium Yalta, 24-28 September, 2007. The BN800 reactor Cylinder, halved vertical cross section. 1 - zone of core with low Pu content (24.4%)

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17 th AER Symposium Yalta, 24-28 September, 2007

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  1. USE OF VVER SPENT FUELS IN A THORIUM FAST BREEDERP. Vértes, KFKI Atomic Energy Research Institute, Budapest, Hungary 17th AER Symposium Yalta, 24-28 September, 2007

  2. The BN800 reactorCylinder, halved vertical cross section 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

  3. Thorium fast breeder reactor model (Based on BN800 fast reactor) • Core:Th+Pu+(uranium)=11228.5 kg • Axial breeding blankets:Th=9351.8 kg (4675.9 kg in the 3rd case) • Radial breeding blanket:Th=25682.2 kg • The heavy metal in the core is consisted of • Pu+MA as come from a 39.6 MWday/kg burned and 3 years cooled VVER-440 assembly • uranium (U232, U233, U234, U235) breeded in earlier cycles either in the core or in the blankets • thorium The Pu+MA component is distributed among the zone of core as 0.288, 0.323 and 0.389

  4. Condition of operation • Power: 2100MWth, • Burnup cycle: 165 days • A burnup cycle is divided up to 10 burnup steps • The initial composition of each B.C is chosen that thekeffonly after the last burnup step becomes less than1 • The irradiated thorium is cooled 165 days (to let the Pa decay to uranium) • Uranium isotopes are extracted from blankets and are placed into the core together with new Pu+MA fuels and the cycle starts again.

  5. Case 1: Thorium blankets are on both axial sides, reactor is cooled with sodium No Pu+MA required after 11th cycle! After 15 cycles: • Total amount of Pu+MA required: 10311 kg • Total amount of Pu+MA left: 8480 kg • Total number of spent VVER assembly: 7389 • Total amount of required Thorium: 54962 kg • Amount of spared: 127kg

  6. Case 2: Pb-Bi coolant No Pu+MA required after 10th cycle After 15 cycles: • Total amount of Pu+MA: 10311.1 kg • Total amount of Pu+MA left: 8340 kg • Total number of spent VVER assembly: 7389 • Total amount of required Thorium: 54962 kg • Amount of spared: 243kg

  7. Case 3: Axial thorium blanket are only bottom, reactor is cooled with sodium After 43 cycles: • Total amount of Pu+MA: 27682 kg, • Total amount of Pu+MA left: 25200 kg • Total number of spent VVER assembly: 19917 • Total amount of required Thorium: 52399.5 kg • Amount of spared: 0kg

  8. Proliferation problem • About 80% U-233 and U-235 in the rest uranium • About 20 kg critical mass • 6 A-bomb in the 1st case, 12 A-bomb in the 2nd case • Th-fast breeder fleet is not an acceptable solution for countries signed the non-proliferation treaty • Other countries may use this solution and may fabricate fuels mixing the breeded uranium with the depleted one

  9. Method of calculation The NOTRADAT system: NJOY⇨BBC⇨TRANSX ⇩ ⇖ DANTSYS⇨TIBSO

  10. The special featuresof NOTRADAT system • nuclear data: each isotope in separate file having standardized name • NJOY processing in batch: generic input is used • TRANSX: composition data may be separated from other control input items • Total power can be calculated not only fission power • Flux, calculated by DANTSYS multigroup SN code normed to required power and used for burnup calculation by TIBSO code • Fuel manipulation can be accomplished by means of TIBSO • New material composition obtained from burnup and possibly from fuel manipulation can be directly used in TRANSX due to an output option of TIBSO • Burnup libraries which may differ in different part of reactor zone can be modified after each burnup cycle In our calculations a 30 group system has been used

  11. References [1] Dekusar V.M., et. al., Feasibility Studies of BN-800 Type Reactor with (Pu-Th)O2 Fuel for Effective Incineration of Minor Actinides, Technical Meeting of the CRP on «Studies of Advanced Reactor Technology Options for Effective Incineration of Radioactive Waste, 22-26 November 2004, Hefei, China [2] P. Vertes, NOTRADAT – a program package for neutronic calculations of nuclear systems, unpublished [3] R. E. MacFarlane, D.W. Muir, NJOY Nuclear Data Processing System, LA-12740, 1994 [4] R. E. MacFarlane, TRANSX 2: A Code for Interfacing MATXS Cross-Section Libraries to Nuclear Transport Codes, LA-12312-MS (July 1992) [5] R. E. Alcouffe, R. S. Baker, F.W. Brinkley, D.R. Marr, R. D. O’Dell, and W. F. Walters, “DANTSYS: A Diffusion Accelerated Neutral Particle Transport Code System,” LA-12969-M (June 1995) [6] Vértes P. Multinodal treatment of production, decay and spreading of radioactive isotopes, Nuclear Technology 1999;128:124-130.

  12. Thank You

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