USE OF VVER SPENT FUELS USE OF VVER SPENT FUELS IN A THORIUM FAST BREEDERIN A THORIUM FAST BREEDER

P. Vértes, P. Vértes, KFKI Atomic Energy Research KFKI Atomic Energy Research Institute, Budapest, HungaryInstitute, Budapest, Hungary

1717thth AER Symposium AER Symposium

Yalta, 24-28 September, 2007Yalta, 24-28 September, 2007

The BN800 reactorThe BN800 reactorCylinder, halved vertical cross sectionCylinder, 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 blanket5 - axial breeding blanket6 - reflector

Thorium fast breeder reactor Thorium fast breeder reactor

modelmodel (Based on BN800 fast reactor)(Based on BN800 fast reactor)

• Core:Core: Th+Pu+(uranium)=11228.5 kgTh+Pu+(uranium)=11228.5 kg • Axial breeding blankets:Axial breeding blankets: Th=9351.8 kg (4675.9 Th=9351.8 kg (4675.9

kg in the 3rd case)kg in the 3rd case)• Radial breeding blanket:Radial breeding blanket: Th=25682.2 kgTh=25682.2 kg• The heavy metal in the core is consisted ofThe heavy metal in the core is consisted of

– Pu+MA as come from a Pu+MA as come from a 39.6 MWday/kg 39.6 MWday/kg burned and 3 years cooled VVER-440 burned and 3 years cooled VVER-440 assembly assembly

– uranium (U232, U233, U234, U235) breeded in uranium (U232, U233, U234, U235) breeded in earlier cycles either in the core or in the earlier cycles either in the core or in the blanketsblankets

– thoriumthorium The Pu+MA component is distributed among the The Pu+MA component is distributed among the

zone of core as 0.288, 0.323 and 0.389zone of core as 0.288, 0.323 and 0.389

Condition of operationCondition of operation• Power:Power: 2100MWth, 2100MWth, • Burnup cycle:Burnup cycle: 165 days 165 days• A burnup cycle is divided up to 10 burnup stepsA burnup cycle is divided up to 10 burnup steps • The initial composition of each B.C is chosen that The initial composition of each B.C is chosen that

thethe keffkeff only after the last burnup step becomes only after the last burnup step becomes less thanless than 11

• The irradiated thorium is cooled 165 days (to let The irradiated thorium is cooled 165 days (to let the Pa decay to uranium)the Pa decay to uranium)

• Uranium isotopes are extracted from blankets and Uranium isotopes are extracted from blankets and are placed into the core together with new are placed into the core together with new Pu+MAPu+MA fuels and the cycle starts again. fuels and the cycle starts again.

Case 1: Thorium blankets are on both axial sides, Case 1: Thorium blankets are on both axial sides,

reactor is cooled with sodiumreactor is cooled with sodium

No Pu+MA required after 11No Pu+MA required after 11thth cycle! cycle!

After 15 cycles:After 15 cycles: Total amount of Pu+MA required: Total amount of Pu+MA required: 10311 kg10311 kg Total amount of Pu+MA left: 8480 kgTotal amount of Pu+MA left: 8480 kg Total number of spent VVER assembly: 7389Total number of spent VVER assembly: 7389 Total amount of required Thorium: 54962 kgTotal amount of required Thorium: 54962 kg Amount of spared: 127kgAmount of spared: 127kg

Case 2: Case 2: Pb-Bi coolantPb-Bi coolant

No Pu+MA required after 10No Pu+MA required after 10thth cycle cycle

After 15 cycles:After 15 cycles: Total amount of Pu+MA: Total amount of Pu+MA: 10311.1 kg10311.1 kg Total amount of Pu+MA left: 8340 kgTotal amount of Pu+MA left: 8340 kg Total number of spent VVER assembly: 7389Total number of spent VVER assembly: 7389 Total amount of required Thorium: 54962 kgTotal amount of required Thorium: 54962 kg Amount of spared: 243kgAmount of spared: 243kg

Case 3: Axial thorium blanket are only Case 3: Axial thorium blanket are only bottom, reactor is cooled with sodiumbottom, reactor is cooled with sodium

After 43 cycles:After 43 cycles: Total amount of Pu+MA: Total amount of Pu+MA: 27682 kg,27682 kg, Total amount of Pu+MA left: 25200 kgTotal amount of Pu+MA left: 25200 kg Total number of spent VVER assembly: 19917Total number of spent VVER assembly: 19917 Total amount of required Thorium: 52399.5 kgTotal amount of required Thorium: 52399.5 kg Amount of spared: 0kgAmount of spared: 0kg

Proliferation problemProliferation problem

About 80% U-233 and U-235 in the rest uraniumAbout 80% U-233 and U-235 in the rest uranium About 20 kg critical massAbout 20 kg critical mass 6 A-bomb in the 16 A-bomb in the 1stst case, 12 A-bomb in the 2 case, 12 A-bomb in the 2ndnd

casecase Th-fast breeder fleet is not an acceptable solution Th-fast breeder fleet is not an acceptable solution

for countries signed the non-proliferation treatyfor countries signed the non-proliferation treaty Other countries may use this solution and may Other countries may use this solution and may

fabricate fuels mixing the breeded uranium with fabricate fuels mixing the breeded uranium with the depleted onethe depleted one

Method of calculationMethod of calculation

The NOTRADAT system:The NOTRADAT system:

NJOYNJOY⇨BBC⇨TRANSX⇨BBC⇨TRANSX

⇩ ⇖⇩ ⇖

DANTSYS⇨TIBSODANTSYS⇨TIBSO

The special featuresThe special features of NOTRADAT systemof NOTRADAT system

► nuclear data: each isotope in separate file having nuclear data: each isotope in separate file having standardized name standardized name

► NJOY processing in batch: generic input is usedNJOY processing in batch: generic input is used► TRANSX: composition data may be separated from other TRANSX: composition data may be separated from other

control input itemscontrol input items► Total power can be calculated not only fission powerTotal power can be calculated not only fission power► Flux, calculated by DANTSYS multigroup SN code normed to Flux, calculated by DANTSYS multigroup SN code normed to

required power and used for burnup calculation by TIBSO coderequired power and used for burnup calculation by TIBSO code► Fuel manipulation can be accomplished by means of TIBSOFuel manipulation can be accomplished by means of TIBSO► New material composition New material composition obtained from burnup and possibly obtained from burnup and possibly

from fuel manipulation can be directly used in TRANSX due to from fuel manipulation can be directly used in TRANSX due to an output option of TIBSOan output option of TIBSO

► Burnup libraries which may differ in different part of reactor Burnup libraries which may differ in different part of reactor zone can be modified after each burnup cyclezone can be modified after each burnup cycle

In our calculations a 30 group system has been usedIn our calculations a 30 group system has been used

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.

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