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PRESS RELEASE |
Kalpakkam
3rd September 2002
MIXED CARBIDE FUEL REACHES A BURNUP OF 100, 000 MWd/t IN FBTR
The Fast Breeder Test Reactor at Indira Gandhi Centre for Atomic Research, Kalpakkam uses a novel indigenous fuel with 70% plutonium carbide and 30% natural uranium carbide. The fuel was designed in the Indira Gandhi Centre for Atomic Research and pin fabrication was carried out at the Bhabha Atomic Research Centre, Trombay, Mumbai. The Nuclear Fuel Complex, Hyderabad supplied the stainless steel hardwares and assembled the pins into a fuel subassembly. The fuel reached a burnup of 100,000 MWd/t on 3rd September without any pin failure. The fuel “burnup” in a nuclear reactor refers to the energy extracted from the fuel before it is discharged for storage or reprocessing. The higher the burnup, the less will be the fuel cycle cost due to less quantity of fuel fabrication, reprocessing and waste management. The fuel burnup in Pressurized Heavy Water Reactors is about 7,000 MWd/t average, whereas the same is about 40,000 MWd/t in Pressurized Water Reactors. In the early 80’s when this fuel was selected for FBTR, in the absence of any data a conservative estimation of the burnup was 25,000 MWd/t. After achieving the initial targeted value, a fuel subassembly was taken for post irradiation examination in hot cells attached to FBTR. The examination of the highly radioactive fuel indicated that the fuel growth rate due to burnup is lower than what was assumed and that it is capable of further burnup and therefore, it was taken to 50,000 MWd/t. At this stage one more fuel subassembly was taken out for post irradiation examination and it showed that the fuel is performing well with no traces of corrosion from sodium , no strain on the clad and fission gas release was only about 15%. There are residual porosities in the fuel , indicating that further burnup is possible.
Based on the post irradiation examination results and extensive analysis using a computer code, it is found that the fuel is capable of undergoing a burnup of 105,000 MWd/t. When the reactor will be shutdown for refueling, by Mid September, one more subassembly which has reached high burnup, will be taken out for post irradiation examination. Achieving of high fuel burnup is very important milestone in the development of breeder reactor.
Such high burnup could have been achieved last year but for water leakage in the biological shield concrete cooling coil and leakage of 75 kg sodium from the primary purification circuit. Both these incidences were overcome and the reactor is operating well. During the current campaign, the fuel linear power rating was raised to 400 W/cm which was the original design objective. The present power level of the reactor is 17.5 MWt and the maximum electricity generation is 2.8 MWe. The reactor is in continuous operation for the last 30 days without any shutdown. The total generation of electricity during this campaign is 1.2 million units.
The sodium systems are behaving well. The purity of sodium is maintained less than 1 ppm very easily. The various components viz. Control Rod Drive Mechanisms, Sodium Pumps, Steam Generators and Fuelling Machines are operating very well. The operating time for each of the sodium pump has crossed 120,000 h. The pumps have not been taken out of sodium for any maintenance so far during the last 16 years of operation. There is no leak in the steam generator. Commissioning of FBTR fuel reprocessing plant called lead mini cell is in progress and is expected to start fuel processing in a few months. This would be an important step in the development of Breeder Reactor Fuel Cycle.
Director, IGCAR
Kalpakkam