Fuel Performance, Design and Development in Indian Reactors

Abstract

Presently twelve 220 MWe Pressurized Heavy Water Reactors (PHWRs) and two Boiling Water Reactors (BWRs) arc in operation in India. The normal fuel configuration for operating 220 MWe PHWRs is natural uranium dioxide nineteen element fuel bundle. So far, 65 full power years of PHWR operation and 38 full power years of BWR operational experience has been accumulated. This corresponds to irradiation of 250 thousand PHWR fuel bundles and 2700 BWR bundles. Fabrication of 37-element fuel bundle for two 540 MWe units under construction is being taken up. Design and development studies of 680 MWe PHWR units by introducing boiling in channels has been taken up Based on the reactor operating experience; the fuel design, manufacturing quality control and the reactor operating practices; are under continuous evolution in order to improve the fuel performance and ease fuel fabrication. The overall fuel failure rate currently is about 0.1 % and efforts are on to further reduce it. The core discharge burnup in different reactors is around 7000 MWD/TeU. In addition to natural uranium fuel bundles, 232 numbers of Thorium dioxide bundles have been irradiated as a part of initial flux flattening in different reactors. It is planned to irradiate, in addition to natural uranium fuel bundles, depleted uranium and mixed oxide fuel bundles in PHWRs. The fuel design for the MOX bundle has been completed. The fuel fabrication specifications have been prepared. The reactor physics lattice and core calculations optimising the core loading pattern with these bundles has been finalised. The loading is planned to be carried out in an operating unit. The safety analyses for the core using these bundles has been reviewed by regulatory authorities.