WWER Fuel Performance and Modelling Activities in Bulgaria

Transcription

1 WWER Fuel Performance and Modelling Activities in Bulgaria Maria Manolova INRNEBAS, Sofia, Bulgaria TWGFTP Meeting Vienna, IAEA, April 2010 Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA 1

2 OUTLINE Kozloduy NPP Fuel Failures, Unit 14, 1 WWER440 Unit 56, 5 WWER1000 Fuel Performance Modelling Computer Codes FUMEX Programs International Conference Organization IRTSofia Research Reactor Fuel Shipment Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA 2

3 Kozloduy NPP Fuel Failures, Root causes Statistics Fuel failure criteria Operational events FAs type Compensatory measures Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 3

4 Kozloduy NPP Fuel Failures, Units 14, WWER440 Analysis of the possible causes for nuclear fuel failures is performed in the frame of contract between Kozloduy NPP and RRC Kurchatov Institute Moscow in Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 4

5 Kozloduy NPP Fuel Failures, Units 14, WWER440 Possible reasons for fuel failure: manufacturing defects; operational regime of units; increased hydraulic characteristics in the core resulting in the increasing vibrations of the core elements; chemical regime in the primary circuit and corrosion processes in the core; placing the dummy assemblies. Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 5

6 Kozloduy NPP Fuel Failures, Units 14, WWER440 Number of Fuel Failures Year Unit 1 Unit 2 Unit 3 Unit TFAs LFAs TFAs LFAs 107 Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA TFAs LFAs TFAs LFAs

7 Kozloduy NPP Fuel Failures, Units 14, WWER440 TFAs Tested fuel assemblies LFAs Leaking fuel assemblies Methods for individual FAs control: , Wetcanister , Wetcanister, Unit , Sipping test, Unit 4 Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 7

8 Kozloduy NPP Fuel Failures, Units 56, WWER1000 Failure criteria 1. Failure criteria for leaking fuel, based on 131 I activity, obtained by the results from the Fuel Cladding Integrity Control (FCIC) FA type Operation time 131 I Activity Application TVS in operation till Ci/kg till 2003 TVSM ( Bq/kg) Ci/kg ( Bq/kg) from 2003 till now TVSA in operation since 2004 till now Ci/kg ( Bq/kg) 2. Failure criteria, based on an evaluation of mechanical and corrosion damages of the fuel Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 8

9 Kozloduy NPP Fuel Failures, Units 56, WWER Operational Event: Delayed Rod Control Cluster (RCC) insertion into the core of Unit 6 (over 4.00 sec) Problem identified at NPP operating WWER 1000 in Russia, Ukraine and Bulgaria FAs type TVS base model for twoyears fuel cycle Root cause Analyses performed by Chief Designer OKB Gidropress, Kurchatov Institute and other institutes. Analysis finds out the root cause is the bow of FA skeleton. Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 9

10 Kozloduy NPP Fuel Failures, Units 56, WWER Compensatory measures Decreasing the RCC drop time by Increased RCC weight Increased RCC weight of drives and bars Drilled RCC drive bars Measurement of RCC insertion times with the aim to monitor the problem and to make the correction actions if needed New FA design with increased FA skeleton stability Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 10

11 Kozloduy NPP Fuel Failures, Units 56, WWER Mechanical defects of the FAs 2001 Unit 5 Because of mechanical defects and FCIC results a few FAs were discharged from the rector core before their end of life: 2 FAs operated one fuel cycle (8 th fuel cycle) 12 FAs operated during two fuel cycles (7 th and 8 th ) FAs type Improved FAs type TVSM (in serial production since 1996). Main construction differences new FR bottom ends, new FA bottom nozzle support Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 11

12 Kozloduy NPP Fuel Failures, Units 56, WWER1000 Root causes For the leaking FAs operating in the reactor core of Unit 5 probably has a complex character and it is due to: Change in the construction of FR bottom ends Unreliable fixation of the FR to the bottom spacer grid FR Cladding bottom parts fretting wear Change in the construction of FA bottom nozzle support Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 12

13 Kozloduy NPP Fuel Failures, Units 56, WWER Unit 6 After the end of 7 th fuel cycle of Unit 6, during the 2002 reloading, all 108 FAs to be reloaded in the 8 th fuel cycle have been visually inspected. 5 FAs with mechanical integrity failures were found. The management of NPP Kozloduy took a decision not to allow reloading of these FAs in the reactor core. Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 13

14 Kozloduy NPP Fuel Failures, Units 56, WWER1000 Root causes for Unit 6 FAs mechanical integrity failures have complex character, including. Construction of FR bottom ends Unreliable fixation of FR in the lower spacer grid Insufficient FA bottom nozzle support Different materials of the FR cladding and lower grid resulting in fretting wear of FR cladding bottom parts. Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 14

15 Kozloduy NPP Fuel Failures, Units 56, WWER1000 FA design improvements 1. Change in the construction of FA bottom nozzle support 2. Change in the construction of FR bottom end support 3. Change in the fuel column fixing in the FR upper part 4. Changing of the thickness of the lower spacer grid Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 15

16 Kozloduy NPP Fuel Failures, Units 56, WWER1000 Transition to the new generation of FAs TVSA during the period In this way the problem has been finally solved. No fuel defects and failures have been found during and after the transition to the new fuel type. Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 16

17 Fuel Performance Modeling More then 15 years INRNE researchers work on modeling and studying of the inreactor fuel performance at normal and offnormal conditions. Computer codes TRANSURANUS FEMAXI6 PINw99 PINmicro Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 17

18 Fuel Performance Modeling TRANSURANUS code One of the widely used and powerful computer codes for studying standard reactor fuel behaviour for WWER s, operated in the East European countries Developed to high level of reliability at the Modelling Group of the European Commission Institute for Transuranium Elements in Karlsruhe, Germany Covers fuel performance modeling for different fuel subtypes and irradiation conditions The WWER version of the code has been developed with intensive participation of a team of INRNE specialists in close coordination and cooperation with the Modelling Group of the EC ITU Karlsruhe, Germany Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 18

19 Fuel Performance Modeling TRANSURANUS code validation Some of the data sets used from the IFPE Database The GAIN program, compiled in the IFPE; 4 (UO 2 +Gd 2 O 3 ) rods, offers very good opportunities for testing fuel performance codes in the case of Gddoped fuel; covers: changes of fuel rod length and diameter; pin pressure and FGR WWER1000 FA4108 irradiated in Novovoronezh NPP, investigated in the hot cells of NIIAR : measured rod length; clad diameter and fuelcladding gap Ramp tests of WWER440 fuel in the MIR reactor 9 rods preirradiated in KOLA3 WWER unit up to Bu max ~ 60 MWd/kgU), fuel temperature; pin pressure; FGR (FUMEXIII). TRANSURANUS code simulation of fuel rod transient and loadfollow regimes of operation leading to local PCMI effects and possible cladding failures will be performed for the rods of FUMEXIII program Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 19

20 Fuel Performance Modeling Participation in the IAEA CRP FUMEX on model development and code validation for high burnup fuel FUMEXI ( ) PINmicro code FUMEXII ( ) TRANSURANUS code and PINw99 code FUMEXIII ( ) TRANSURANUS code and FEMAXI6 code Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 20

21 Fuel Performance Modeling International Conference Organization Organization and hosting, in cooperation with the IAEA, of the 1 st, 2 nd, 3 rd,4 th, 5 th, 6 th,7 th and 8 th International Seminars / Conferences on WWER Fuel Performance, Modelling and Experimental Support 1994, 1997,1999, 2001, 2003, 2005, 2007, 2009 The 9 th Conference, 1724 Sept. 2011, under preparation Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 21

22 IRTSofia Research Reactor Operated by the INRNEBAS, safely shipped all of their Russianorigin nuclear fuel from Bulgaria to the Russian Federation beginning in 2003 and completing in According to the Resolution of the Bulgarian Council of Ministers from 2001 IRT2000 is in process of reconstruction into a low power reactor up to 200 kwk These fresh and spent fuel shipments removed all highly enriched uranium (HEU) from Bulgaria. The HEU shipments were assisted by the Russian Research Reactor Fuel Return Program (RRRFR) of DOE of USA, in close collaboration with IAEA Intermediate Meeting of the TWGFTP, April 2010, Vienna,IAEA 22

23 IRTSofia Research Reactor Fuel Quantities Shipped Fresh Fuel by air in December 2003 using trucks and a commercial cargo aircraft HEU: kg, 28 type IRT2M FAs (36% enrichment) Spent Fuel July 2008, Combined spent fuel shipment of HEU and LEU was completed using high capacity Škoda VPVR/M casks transported by truck, barge, and rail HEU: 6.44 kg, 16 type C36 FAs (36% enrichment) LEU: kg, 58 type EK10 FAs (10% enrichment ). Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA 23

24 References 1. Analysis of core operation of Units 13 NPP Kozloduy, Report RRC Kurchatov Institute, 1994 (in Russian) 2. Methodology for calculation of coolant flow through fuel assemblies of rector cores of Units 14 of NPP Kozloduy, 230P081, 2001 (in Russian) 3. Kozloduy WWER440 Fuel Performance Review. V.Tzotcheva, I.Assenov, G.Neshovska, Third Int.Seminar on WWER Fuel Performance, Modelling and Experimental Support, 48 October 1999, Pamporovo, Bulgaria 4.Methods and approaches for control, criteria for evaluation of mechanical damages of the WWER1000 fuel assemblies during reactor operation. Quality Instruction. 5. Kozloduy NPP WWER1000 Fuel and Control Rods Performance, Y.Georgiev. Third Int.Seminar on WWER Fuel Performance, Modelling and Experimental Support, 48 October 1999, Pamporovo, Bulgaria 6. RER3006/9004/01 Regional Workshop of Russian Research Reactor Fuel Return Program Lessons Learned, Varna, Bulgaria, 2225 June Experience of Shipping Russianorigin Research Reactor Spent Fuel to the Russian federation. IAEATECDOC1632 Intermediate Meeting of the TWGFTP, April 2010, Vienna, IAEA, IAEA 24

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