Radiological analysis for the Dhruva supplementary control room

Dhruva is a 100-MWth high flux research reactor, sited at Trombay, Mumbai. It is cooled, moderated and reflected by D2O, and has a max. thermal neutron flux of 1.8x1014 n/cm2-s. The reactor has a vertical core and uses natural uranium metal fuel clad in aluminium, and Cd shutoff rods as the primary shut-down system. The core consists of 127 fuel assemblies, each having a 7-pin uranium cluster, with a total weight of the fuel in core of about 6.5 t natural uranium. The coolant enters the core at the bottom inlet plenum and exits from the top. The reactor has a low-pressure concrete containment. In view of the recent trends in reactor safety, it has been decided to provide supplementary control room (SCC) for Dhruva from where the reactor can be tripped and the safety parameters can be monitored over a long period in case the main control room (MCR) becomes unavailable. The reasons for the unavailability could be inhabitability or inaccessibility of the MCR on account of radiological, fire, structural damage, or other causes. Two locations have been marked in the Service Building for providing SCC. This paper examines the merits of the suggested locations from the radiological point of view