Radiation protection aspects of the accident recovery

On the Unit 2 at Paks Nuclear Power Plant accident occurred on 10th April 2003. Thirty fuel assemblies damaged in the cleaning tank installed in the Pit No. 1. Due to the accident casing of the fuel elements and uranium-dioxide pellets inside them damaged. The scratched fuel assemblies and nuclear fuel fragments should be removed and safely deposited. In order to restore the operational condition of the Pit No. 1 a lot of complicated activities with radiation hazard should be implemented. These tasks bring up both technical difficulties and serious radiation protection problems, and it is essential to resolve them in order to reduce radiation exposure of the working personnel and to minimize the amount of off-site radioactive releases. This research-development topic covers radiation protection issues concerning the restoration of the Pit No. 1 on the Unit 2 at Paks NPP. Among other things, new radiation protection monitoring systems installed inside the Pit No. 1, radiation protection model calculations used during the preparation of restoration, organizational and technical measures to be used during the preparation and implementation phases, measures taken in order to prevent, reduce radiation exposure of the personnel, and the required limitations are presented. Also the results of the measurements performed so far and lessons can be learned from the results are demonstrated. The planned airborne and liquid radioactive releases, the ratio of the planned releases and their limits, and public overexposure originated from the planned releases are also presented. It is justified that restoration activities can be implemented with suitable radiation protection measures not failing the limits for releases and radiation exposure limits specified for the personnel and the public. (author)