Calculation of dose rates in loss of coolant accident due to double ended rupture of the experimental tangential irradiation beam tube of MTR reactor.

Abstract

The doses and dose rates following a LOCA in a MTR reactor have been studied. A MTR reactor is an open water pool reactor type. The water pool serves as a shield from radioactive radiations.The most serious accident in this type of reactors is the Loss of Coolant Accident (LOCA) due to rupture either of a primary coolant pipe or of any experimental beam tube. In the present work, it has assumed that pool water drains out due to double ended rupture of the tangential irradiation beam tube (TIC) which has a diameter 150 mm. For an operating power level of 22 MW, the equilibrium core would enter into melting conditions if the pool drain time is less than one hour.It was also assumed that Emergency Core Cooling System (chimney water injection system and siphon effect breaker were not working. Therefore conservatively a severe damage (~80%) is expected to occur to the core, either by a core uncover situation following extended boiling operation, or by a core covered situation with extended boiling.The reactor building, reactor hall and control room, have been modeled using the Monte Carlo N-Particle Transport code (MCNPX 2.7.0). The source term has been determined using the ORIGEN-2 code. The doses and dose rates calculations in different places of operator (as phantom of Tissue-Equivalent Material) inside of the reactor building were determined using the Monte Carlo N-Particle Transport code (MCNPX).The results show that the dose rate in the control room would be 5.24557 SV/h, the dose rate in the reactor hall above the pools on the gate would be7.20137 SV/h and the dose rate in the emergency control room would be 2.68239 SV/h. These dose rates are extremely high and would lead to fatal doses in short time.

Comprehensive power quality performance assessment for electrical system of a nuclear research reactor

“…Among the basic safety conditions related to a research reactor are cooling of the reactor core after shutting down the reactor 34 . Accidents or incidents may occur in case of losing reactor coolant pumps which their main function is to remove and transfer the amount of heat generated in the reactor core by providing forced primary coolant flow to the reactor core 35 .This NRR is operating with two core cooling pumps (2000m 3 /h) at its full power (22 MW thermal) 36 and there are a lot of single phase loads on this facility.…”