Use of depleted uranium in equilibrium core of standard PHWRs: a complete study

The PHWRs have been designed to use natural uranium in their equilibrium state. The use of depleted uranium in the Indian PHWRs was limited (384 bundles) to provide the flux flattening in the fresh core, which facilitates to operate the reactor very close to the rated power during the initial period of operation. However, in the equilibrium core the flux flattening is maintained by dividing the core into two burnup zones and adopting the differential refuelling scheme in the two burnup zone core. The regular use of the depleted uranium in the equilibrium core of 220 MWe reactor has been achieved by using the differential enrichment in the two zones of the core. The loading of the depleted uranium has been optimised to maximise the natural uranium saving without changing the reactor hardware. This paper describes the complete study carried for the regular use of depleted uranium in Indian standard PHWRs (220 MWe). (author)