In an interim report, Axpo informed the general public on the work being carried out on the reactor pressure vessel of Beznau 1. What is the situation at the moment? We asked Mike Dost, the Head of KKB.
Mike Dost, why another delay?
Due to the complexity of the tasks and their interdependencies, the proof of integrity has turned out to be more time consuming than originally anticipated. In particular, the procurement of comparable material samples with a similar inclusion density is challenging both in terms of time and from a legal perspective.
Does the delay mean that the situation at KKB1 is worse than originally communicated?
No. Axpo strives to maintain the utmost transparency. We always inform the general pubic as soon as substantiated statements can be made. The new schedule is due to entirely practical factors.
Can you give us more details about the delay in procuring material samples?
Here not only procurement, but also suitability testing of the additional samples is very involved. In addition, the testing and analysis processes are extremely complex, sometimes involving several months of work. Axpo is also dependent on the availability of specialised companies to carry out these examinations. Numerous legal and commercial issues in connection with the ownership and utilisation rights of these test pieces must be clarified with the partners and suppliers.
Have you already been able to find test specimens?
Yes. We have already been able to locate and analyse various test pieces and more will follow. We are currently also examining the accelerated irradiation of specimens that were fabricated from original reactor pressure vessel forgings, and that were used in the area with the highest neutron irradiation.
What do you hope to gain from the additional material tests?
We want to additionally validate current findings with the material examinations on test pieces.
Is Axpo still of the opinion that the irregularities are inclusions and not dreaded hydrogen flaking?
The location and distribution, as well as the size of the irregularities speak against hydrogen flaking. The chemical composition of the steel also indicates the contrary. In-depth investigations confirm initial assessments: The inclusions are non-metallic inclusions in the raw material that occurred during the fabrication process and, therefore, were not induced during operation.
What else is required for proof of safety?
We will have fulfilled the proof of safety requirements when the tests and analyses have been completed with results that we consider positive. To do so, the impacts of the detected irregularities on the RPV have to be clarified. We have to investigate the influence of the irregularities on the material properties, provide proof of fracture toughness, and rule out any remaining safety reservations. The proof of integrity for the so-called “safety case” can be provided on this basis.
Is the plant still viable?
From an economic standpoint, the continued operation of the Beznau nuclear power plant makes sense as long as a positive operative free cash flow, e.g. a positive contribution margin, is generated in the long term. This is still the case for the long-term outlook. Of course, current low wholesale prices are impacting the profitability of the plant significantly.
What are the costs of the outage?
The renewed restart postponement results in high costs. Depending on the issues that will have to be clarified in the course of the on-going process, investigation expenses and the loss of revenues from electricity sales since August 2015 will cost Axpo about CHF 200 million.
Where is the threshold?
That’s a complex question. In comparison to the costs that would be incurred due to a scheduled or partially scheduled outage, the costs of the current, additional delays are manageable. Of course there is a threshold – we are doing everything possible to avoid reaching this limit.