30.11.2015 - Examinations on the two reactor pressure vessels of the Beznau nuclear power plant have reached additional important milestones. KKB will submit a roadmap for the further analysis and testing process on Unit 1 today. Measurements on Unit 2 are in an advanced stage. Contrary to Unit 1, no abnormal results were found here. At present, nothing should stand in the way of the scheduled restart at the end of December 2015 following the completion of the Unit 2 revision.
Ultrasonic measurement findings on KKB Unit 1 in July 2015 indicated faults in the raw material of the reactor pressure vessel, and were the subject of further investigations. Based on current information, it is most likely that these irregularities were due to minute inclusions that occurred during the fabrication of the forged rings.
Since then, extensive analyses and calculations have been carried out by internal and external experts. In August, the Federal Nuclear Safety Inspectorate (ENSI) called for additional investigations. KKB decided to carry out additional measurements with a special testing method developed for a Belgian reactor. These measurements are currently being assessed, however, to a large extent, they confirm the findings of measurements carried out in the summer of 2015. In December 2015, KKB will submit the new, provisional test report to the Swiss Association for Technical Inspections (SVTI/ASIT) and then to ENSI.
As a result, the analysis and testing process that commenced in July on the basis of the first measurements begins anew. The extensive analysis and testing phase takes several months and is carried out with an international committee of experts nominated by ENSI. KKB must prove that the integrity of the reactor pressure vessel has not been compromised despite the irregularities that were found. Based on the current results, KKB remains convinced that Unit 1 will go back on grid after completion of the testing phase. However, the upcoming analyses and certificates will take a great deal of time so that a restart approval for KKB Unit 1 is not expected before the end of July 2016.
Up to now, the ultrasonic measurements on Unit 2 have only resulted in minute findings, which according to KKB experts are normal based on their number and location. The respective test report will be submitted to SVTI/ASIT in the next few days. Should the supervisory authorities assess the report positively, KKB Unit 2 will go back on grid as scheduled at the end of December 2015.
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