SCHOTT, an expert provider of glass-to-metal electrical penetration assemblies to the nuclear power industry, has welcomed a report released by the International Atomic Energy Agency (IAEA) highlighting the potentially severe issues that can occur as a result of complete failure of electrical and instrumentation and control (I and C) equipment under severe accident conditions.
The report, the latest in the IAEA TECDOC Series, is entitled Assessment of Equipment Capability to Perform Reliably under Severe Accident Conditions, and highlights the fact that severe accidents can 'subject electrical and instrumentation and control (I and C) equipment to environmental conditions exceeding the equipment's original design basis assumptions (DBA).'
Furthermore, it recommends that when qualifying electrical and I and C equipment for use within nuclear power plants, components should be tested to be able to withstand severe accident conditions – such as a core melt. Its objective is to provide 'an international technical basis to be considered when assessing the electrical and I and C equipment reliable performance under severe accident conditions needed for implementation of mitigative measures during severe accidents'.
Maintaining the integrity of the containment is key to mitigating severe accidents. This is where glass-to-metal sealed Electrical Penetration Assemblies (EPAs), such as those produced by SCHOTT in its Eternaloc line of components, can play a critical role in nuclear power plant safety. Glass barriers remain hermetic as the material does not degrade like organic epoxy-based variants, even under currently defined severe accident conditions.
Glass barriers are also resistant to radiation leaks, able to withstand extreme temperatures and pressures simultaneously, and provide a hermetic barrier against humidity. In addition, glass barriers have been tested to withstand pressures found under water depths of 12m for up to 30 days – which enables the containment to remain sealed under flooding conditions, whether caused by the event itself or as a consequence of mitigation strategy.
Thomas Fink, General Manager Nuclear Safety Division of SCHOTT, commented: "In the event of a severe accident, the most important area of concern is maintenance of the fission product barrier – effectively maintaining the barrier between the radioactive fuel inside the containment and the outside environment.
The deployment of glass-to-metal seals for electrical penetrations should be considered best and standard practice. This logic applies to all equipment responsible for monitoring and mitigation of severe accidents, such as isolation valves and emergency cooling injectors. The findings and recommendations from the IAEA should be reflected in international and national standards as soon as possible, especially in the UK where major new build plans exist.
All new plants must fulfill these long-term safety requirements as they have targeted operational lifetimes of 60 years. The use of non-aging materials like ceramic, glass, and steel – as recommended by the IAEA – will also reduce total cost of ownership, as components made of these materials do not require maintenance or replacement.
Additionally, costs could be far better managed under a system of universal international standards, as at present each new power plant that is constructed effectively reinvents the wheel due to differing local standards that must be adhered to. SCHOTT welcomes this new report and would encourage regulators to adopt its recommendations at the earliest possible opportunity."
Areva signs MOX fuel fabrication contract with Japan
New AREVA has signed a contract with Japan's NFI (Nuclear Fuel Industries) for the fabrication of 32 MOX* fuel assemblies for the Takahama 3 and 4 reactors operated by Kansai Electric.
The supply of MOX fuel assemblies for Kansai is a follow-up to agreements signed with Japanese utilities from 1975 onwards for the treatment of up to 3,000 tonnes of used fuel at the la Hague site.
The … read more
