In the project plan, the operator must outline the planned steps and methodology for characterising and evaluating the indications. ENSI will now review the plan for completeness and assess the extent to which the method chosen appears suitable for delivering reliable results on the integrity of the reactor pressure vessel. ENSI will issue a review report.
As soon as Axpo submits the documents on the characterisation and evaluation of the findings completing the safety case, ENSI will examine these as well and prepare an opinion report on the safety evaluation of the structural integrity of the Beznau 1 reactor pressure vessel.
Additional external experts
ENSI will include the opinion of a group of international experts in its assessment of Axpo’s safety case. For this reason, upon notification of the indications in the Beznau 1 RPV, ENSI rapidly decided to build up an International Review Panel. The regulator contacted recognised international experts possessing in-depth knowledge in such areas as the safety case of reactor pressure vessel integrity, materials testing, large forging fabrication and non-destructive testing methods.
These experts are consulted in a two-stage process. After reviewing the project plan, the second step is to review Axpo’s analyses and safety case with regard to such aspects as the evaluation of non-destructive measurement results, material testing as well as structural and fracture mechanics analyses taking the indications into account.
“We will incorporate the experts’ recommendations into our safety evaluation report,” says Georg Schwarz, deputy director general of ENSI and division head for nuclear power plants. “Only ENSI is responsible to take the regulatory decision regarding the possible further operation of Beznau 1.”
