July 2003

Irradiation testing of MOX begins at Kalpakkam

newindpress.com, Chennai, 22 July 2003

[Posted 30/07/2003]

Irradiation testing of uranium - plutonium Mixed Oxide (MOX) fuel of 500 MWe Prototype Fast Breeder Reactor (PFBR) began on Monday, in the Fast Breeder Test Reactor (FTBR) at the Indira Gandhi Centre for Atomic Research, Kalpakkam, according to a press release from IGCAR.

As against mixed carbide fuel in FBTR, the MOX fuel has been selected for PFBR because it lends itself to easy fabrication, high burn up and easy reprocessing. MOX fuel irradiation in FBTR requires fissile uranium isotope in order that the chemical composition of the PFBR fuel is stimulated while the desired linear hear generation of 450 W/om is achieved.

The fuel composition is 30 per cent Plutonium Oxide and 70 per cent Uranium Oxide.

The fissile content of Uranium is increased by the addition of U-233 isotope. The MOX fuel sub-assembly will be taken to a burn up of 100,000 MWd/t, after which it will be subjected to post - irradiation examinations. Further MOX subassembly will be introduced into FBTR in step-wise manner, to get statistically irradiation data on the PFBR fuel.

The Uranium 233 used in the subassembly was obtained from the thorium rods irradiated in CIRUS and DHRUVA reactors at Trombay and reprocessed at IGCAR and BARC. The fabrication of the MOX fuel pellets and pins was carried out at Advanced Fuel Fabrication Facility of BARC at Tarapur.

The fuel pin diameter is 6.6 mm and the fuel pellets of 6.66 in diameter, have central holes of 1.8 mm. The sub-assembly contains 37 fuel pins.

Advanced austenitic stainless steel called D-9 is used for cladding tube and hexagonal sheet because of its high strength, corrosion resistance and resistance to neutron induced void swelling. This material was developed jointly by IGCAR, MIDHANI and NFC. The cladding tubes and hexagonal sheaths are fabricated by the Nuclear Fuel complex, Hyderabad. Uranium-233 is being used for the first time in the world.

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