NUCLEAR POWER PLANT A-1 BOHUNICE
NPP A-1 Bohunice with heterogeneous reactor fuelled by natural uranium, moderated by heavy water and cooled by CO2 had been in operation for 4 years. It was finally shut down in February 1977 after an accident (INES level 4). First decommissioning phase occurs in accordance with decommissioning plan. ÚJD issued in 1999 the permit for this decommissioning phase on the basis of “Atomic Act”.
The radioactive inventory at NPP A-1 Bohunice was significantly reduced by the transfer of remaining spent fuel to Russia in 1999, so the main activities in the year 2000 were focused to the increasing of safety during storage of liquid and solid waste and its conditioning. The attention was paid mainly to the spent fuel pond radwaste handling. Using decontamination and shielding, better conditions were created for removal and treatment/ conditioning of remaining radioactive waste from this pond. The new tanks including pipe and transport systems for replacement of “chrompik” (contaminated spent fuel coolant) and store for higher activity level liquid and solid radioactive waste were commissioned in 2000. The preparation of fragmentation project for spent fuel pond internals started.
View of NPP A-1 Bohunice
Chrompik vitrification continued as well as the treatment of low level contaminated scrap using fragmentation and decontamination facilities. The complex technology for fragmentation and decontamination of metallic scrap including stores of conditioned/ unconditioned waste was developed in ex-turbine building after complete dismantling of original equipment.
ÚJD SR evaluated safety documentation relevant to described activities and approved the changes of technical specifications.
View of NPPs Bohunice site
UJD inspected nuclear and radiation safety, fire protection, decommissioning and radioactive waste management, changes influencing safety and readiness of new technologies for operation. The inspection of NPP A1 Bohunice safety aspects were combined with those general for all nuclear facilities operated by SE- VYZ, e.g. training and qualification of personnel, emergency preparedness and quality insurance. Usual problems at NPP are connected with insufficient documentation control and delay of time schedule for individual tasks. Operator continuously fulfils the requirements imposed by ÚJD SR. One event (INES level 0) occurred at NPP A1 Bohunice in 2000.
INTERIM SPENT FUEL STORAGE BOHUNICE
An interim spent fuel storage Bohunice serves to temporarily store the spent fuel from the NPP V-1 and V-2 Bohunice before it is transported to a reprocessing facility or disposed of at a repository. The original storage capacity of fuel assemblies had nearly tripled over the period between 1998 and 2000. This was achieved through the use of new types of containers with a higher storage capacity of fuel assemblies and closer storage thereof in the interim spent fuel storage Bohunice existing pools. These changes also called for an increase in the capacity of cooling and ventilation systems.
In the course of finishing works on the interim spent fuel storage Bohunice reconstruction in 2000, seismic upgrading and modifications to the process systems were completed. All of the reconstructed systems and components were comprehensively tested.
During 2000 the assessment of activities associated with the interim spent fuel storage Bohunice reconstruction was oriented to finishing work and the collection of necessary documents to issue an UJD’s decision permitting the start of interim spent fuel storage Bohunice operation following the reconstruction. The final version of the schedule for filling the compact containers and placing thereof in interim spent fuel storage Bohunice pools, the Programme for the Reconstructed interim spent fuel storage Bohunice Commissioning, the interim spent fuel storage Bohunice Preparation Safety Report after seismic upgrading and enhancing of the storage capacity and the final protocol on completion of contractual tests of the reconstructed interim spent fuel storage Bohunice were submitted to UJD for review and approval by the operator of the interim spent fuel storage Bohunice. Following up on review and approval thereof as well as of other documents required by the “Atomic act“, UJD issued a decision permitting the reconstructed interim spent fuel storage Bohunice commissioning.
The control activity was carried out under UJD inspection plan for 2000. Two controls for spent fuel storage were conducted. These were aimed at checking of compliance with the Limits and Conditions and operating regulations for respective equipment operation. No violation of the conditions and operating regulations was found in either case. A special inspection was focussed on realization of seismic strengthening of construction parts of the storage. Revealed incompatibilities with the design were either corrected on justified by the designer as necessary and incorporated to the safety documentation.UJD assessed the interim spent fuel storage Bohunice operation as safe.