Nuclear Fuel for VVER Reactors. Current Status and Prospects

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6th International Conference on WWER Fuel Performance, Modelling and Experimental Support 19–23 September 2005, Albena Congress Center, Bulgaria

TVEL Corporation

Nuclear fuel for VVER reactors. Current status and prospects

19-23 September, 2005 V.L. Molchanov Nuclear fuel for VVER reactors

Main factors determining burnup and operating life of nuclear fuel

Fuel assembly performance

Fuel rod performance

Core physics

Technical and economic indicators

Nuclear fuel for VVER reactors. Current status and prospects 2 Nuclear fuel for VVER reactors

Post-irradiation Operating tests: experience: Core physics: 1) Design criteria are fulfilled; 1) New design 1) Oxide layer on fuel constraints which allow rod (FR) cladding does 2) 5 TVSA stayed at to introduce loading not exceed 15 µm; Kalinin-1 for 6 years up pattern like complete to burnup of 59 2) Fission Gas Release «in-out»; MW×days/kgU; does not exceed 3%; 2) Flexible fuel cycles 3) 12 working 3) Satisfactory assemblies (WA) condition of cladding. operated at Kola-3 for 6 years up to burnup of 57 MW×days/kgU.

Nuclear fuel for VVER reactors. Current status and prospects 3 Post-irradiation fuel studies

JSC TVEL arranges for post- irradiation studies of full-scale fuel assemblies. During the studies the following is determined: - geometry parameters; - condition of FA components; - properties of zirconium-based materials and fuel composition; - oxidation and hydrating degree; - causes of fuel rod failure. 3 мм

25 мкм

Nuclear fuel for VVER reactors. Current status and prospects 4 Nuclear fuel for VVER-440 reactors

Type 2004 2005 2006 2007 3.82% (WA and FA SA vibration resistant V-230 Kola NPP design and for V-230 reactors) V-213 4.25% (second generation of WA and FA SA ) Dukovany NPP V-213 3,82;4,38% 4,25% Mohovce NPP V-213 3,82% 4,25% V-230 3,82% Bogunice NPP V-213 3,82% 4,25% Paks NPP V-213 3,82% Novovor. NPP V-179 3,82% Rovno NPP V-213 4,21% Loviisa NPP V-213 4,0% Kozloduy NPP V-230 3,6% Armenian NPP V-270 3,6%

Nuclear fuel for VVER reactors. Current status and prospects 5 Nuclear fuel for VVER-440 reactors

Second generation assemblies with improved technical and economic Design parameters, demountable WA with U-Gd fuel 1. 5-year fuel cycle with operation of some assemblies during the 6-th year Fuel cycle 2. Campaign duration 250-330 eff.days 3. Maneuvering modes

Nuclear fuel for VVER reactors. Current status and prospects 6 Nuclear fuel for VVER-440 reactors

Design Assembly parameter Second Standard generation Fuel rod pitch in the bundle, mm 12,2 12,3

Diameter of fuel pellet central hole,mm 1,4 1,2

Fuel column height, mm 2420 2480 Fuel cycle Fuel cycle characteristics 4-year 5-year

Number of make-up FAs, pcs 84 66 Average enrichment of working assemblies, % 3,82 4,25 Burnup, MW×day/kgU 41,6 / 45,0 52,0 / 57,0 (average/maximum),

Nuclear fuel for VVER reactors. Current status and prospects 7 Nuclear fuel for VVER-440 reactors

Use of VVER-440 fuel in maneuvering modes

Control system Primary Secondary Tertiary

Power change 97.5±2.5%Nnom 100-80-100 100-50-100 Nnom range, maximum Nnom

0.5%Nnom/min Power change 2.5%Nnom/min 1.0%Nnom/min (N < 80%Nnom) rate 2.5%Nnom/min (N ≥ 80%Nnom) 250 Number of power Unlimited 2000 (N < 80%Nnom) change cycles 500 (N ≥ 80%Nnom)

Nuclear fuel for VVER reactors. Current status and prospects 8 Nuclear fuel for VVER-440 reactors

Head

Angle fixing to spacer Rigid angle

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Хвостовик

Design of uncased working assembly RK-3

Nuclear fuel for VVER reactors. Current status and prospects 9 Nuclear fuel for VVER-440 reactors

Main characteristics of fuel cycles based on the second generation assemblies and uncased assembly RK-3 Characteristics Second Uncased RK- generation 3 assembly 1. Number of fresh assemblies for 66-72 60 refueling, pcs 2. FA maximum in-pile operation 6 6-7 time, years 3. Average enrichment of make-up 4,2 4,6 fuel, % 4. Maximum burn-up of unloaded 57 65 fuel, MW.days/kgU 5. Time of reactor operation 330 330 between refuelings, eff.days

Nuclear fuel for VVER reactors. Current status and prospects 10 Nuclear fuel for VVER-1000 reactors

2004 2005 2006 2007 Balakovo NPP TVS-2 (enrichment 4.4%)

Volgodonsk NPP UTVS TVS-2 or TVSA

Kalinin NPP TVSA (enrichment up to 4.95%)

Ukrainian NPPs TVSA (enrichment 4.4%)

Kozloduy NPP TVSA (enrichment 4.4%)

Nuclear fuel for VVER reactors. Current status and prospects 11 Nuclear fuel for VVER-1000 reactors

Relief of design conservatism

Decision «On Activities to Clarify Design Constraints with Regard to Power Density for VVER-1000 Cores (V-338, V-320)».

Starting from 22-nd loading (2006 Outage) of Kalinin-1, the new design constraints with regard to power density are to be implemented: • relative power of TVSA (Kq) – 1.40 (design 1.35); • relative power of fuel rods (Kr) – 1.60 (design 1.50).

Nuclear fuel for VVER reactors. Current status and prospects 12 Nuclear fuel for VVER-1000 reactors

Parameter TVS-2

Enrichment, % 4.4

Operation duration, eff.hours 35000

Maximum burnup, MW×days/kgU 55

Fuel pellet diameter, mm 7.57

Pellet central hole diameter, mm 1.4

Uranium amount in FA, kg 494.5

Nuclear fuel for VVER reactors. Current status and prospects 13 Nuclear fuel for VVER-1000 reactors

Change of FA bow at Balakovo-1

Nuclear fuel for VVER reactors. Current status and prospects 14 Nuclear fuel for VVER-1000 reactors

Parameter TVSA

Enrichment, % 4.4 4.95

Operation duration, eff.hours 35000 40000

Maximum burnup, MW×days/kgU 55 65

Fuel pellet diameter, mm 7.57 7.60

Pellet central hole diameter, mm 1.4 1.2

Uranium amount in FA, kg 494.5 505.4

Nuclear fuel for VVER reactors. Current status and prospects 15 Nuclear fuel for VVER-1000 reactors

Change of FA bow at Kalinin-1

15 мм 10

14 ТК 15 ТК 16 ТК 17 ТК 18 ТК 19 ТК 0 1998 1999 2000 2001 2002 2003 2004 Outages, year

Change of measured FA bow Change of measured gap betw een Fas Change of predicted FA bow

Nuclear fuel for VVER reactors. Current status and prospects 16 Nuclear fuel for VVER-1000 reactors

Increase in mass of uranium owing to: Expansion of fuel pellet stack by 150 mm –

total weight of UO2 is 524.1 kg

TVSA-PLUS TVS-2M

Parameter Enrichment, % 4.95 Operation duration, eff.hours 40000 Maximum burnup, MW×days/kgU 65 Fuel pellet diameter, mm 7.60 Pellet central hole diameter, mm 1.2 Axial blankets yes

Nuclear fuel for VVER reactors. Current status and prospects 17 Nuclear fuel for VVER-1000 reactors

Prospective FA design for VVER-1000 reactors suggests: • using of antivibration grid combined with detachable fuel rod collet joint; • using of debris filter; • implementing of 8 spacer grids with increased height for TVSA; • using of intermediate grids with mixing vanes; • using of fuel rods of new design.

Nuclear fuel for VVER reactors. Current status and prospects 18 Fuel rods for VVER-1000s

505.4 kg UO2 per FA 546 kg UO2 per FA

cladding wall thickness 0.65 mm _ 0.57mm fuel pellet outer diameter 7.6 mm _ 7.8 mm

fuel pellet central hole 1.2 mm _ solid pellet

average grain size 10 µm _ 25 µm

Nuclear fuel for VVER reactors. Current status and prospects 19 Fuel cycles for VVER-1000 reactors

Prospective fuel cycles for Russian NPPs with VVER-1000.

Parameter Duration, eff. days 4Ч320*) 5Ч310ч320 3Ч470 Average enrichment of reload 4.4 4.8 4.6 batch, % Number of FAs in reload batch 42 36 70 Maximum FA burnup, 58 68 57 MWЧd/kgU Maximum FR burnup, 64 72 64 MWЧd/kgU

*) under operation at Kalinin NPP-1

Nuclear fuel for VVER reactors. Current status and prospects 20 Conclusion

VVER-440 nuclear fuel

The second generation fuel assemblies with burnup of up to 57 MW×days/kgU have been developed and are introduced. An uncased working assembly of the third generation with burnup of up to 65 MW×days/kgU is under development.

Nuclear fuel for VVER reactors. Current status and prospects 21 Conclusion VVER-1000 nuclear fuel

The main task of further development of nuclear fuel for VVER-1000 reactors is the increasing fuel rod burnup up to 72 MW×days/kgU and operating life up to 6 years through the increase in uranium load in FA and maximum use of potential built-in in the designs of TVSA and TVS-2. They can serve as a basis for promising fuel cycles: 5-year-long and 3х18 month-long.

Nuclear fuel for VVER reactors. Current status and prospects 22 Conclusion (continued)

VVER nuclear fuel

In the nearest future R&D in the field of nuclear fuel for VVER will be directed at: • justification of maneuvering fuel characteristics; • introducing of optimized zirconium alloys.

Nuclear fuel for VVER reactors. Current status and prospects 23