Establishment of technical basis for the nuclear emergency planning and preparedness programme for the Pebble Bed Modular Reactor(PBMR) nuclear power station

Abstract

In this work, description and explanation for the conditions of emergency preparedness is given. The aim was to establish the technical basis for emergency response plans in the event of a nuclear incident that might occur at the PBMR nuclear power station. The Koeberg Nuclear Power Station Technical Basis for Emergency Planning was basically used as a guideline and PC COSYMA, a programme that runs on PC, was used to help ,model the release as described or specified by the regulations set in [5] for South Africa. PC COSYMA runs were done to calculate doses to specific organs and to the whole body. These runs were done considering two weather categories (Pasquill stability category D and F) for neutral and moderately stable weather conditions. Wind speed of 2m/s was used for exposure dose integration periods 1, 10, 30 and 70 days. All dose results (organ and effective) were given by pathways: groundshine, cloudshine and inhalation, except thyroid doses whereby it was assumed that all doses are essentially committed through inhalation. A run for Thyroid including inhalation only as a pathway was also done and a run for iodine prophylaxis as protective action to see the effectiveness of the countermeasures. All the calculated doses were lower than the individual radiation dose limit (50mSv) set by the regulator (NNR) for PBMR [20]. The implementation of countermeasures prevented a further dose accrual. Therefore, there is no need for implementation of countermeasures at PBMR, since they are well below the set criterions. But it will be a good safety culture and Defense in Depth to make an allowance for an emergency plan. Since Defense in Depth is a principle that requires that there should be multiple layers of overlapping safety provision and good safety culture looks at the behaviour on doing things,