Mühleberg upgrade requirements confirmed

Friday, 4 December 2015

The Swiss nuclear safety regulator has reaffirmed the measures that must be taken by utility BKW in order for its Mühleberg nuclear power plant to continue operating until 2019.

The single-unit Mühleberg plant (Image: ENSI)

Although it had a limitless operating licence for Mühleberg, BKW announced in late 2013 that the plant will be permanently shut down in 2019 instead of 2022 as originally planned because of "uncertainty surrounding political and regulatory trends". The single 372 MWe boiling water reactor began operating in 1972.

In January, the Federal Nuclear Safety Inspectorate (ENSI) approved upgrades proposed by BKW for the continued operation of the plant. At that time, ENSI said it would provide a report to the Federal Nuclear Safety Commission (NSC) for a second opinion before publishing its formal order.

Following the NSC's approval of the upgrades, ENSI has now delivered it final decision. This reaffirms the requirement of the upgrades approved in January.

ENSI has requested that BKW perform non-destructive tests on the reactor core shroud during each annual safety review at Mühleberg. It has also set two technical criteria for cracks found in Mühleberg's core shroud, which may not be exceeded. Based on current knowledge, ENSI does not expect the cracks in the core shroud at Mühleberg to reach these limits before its final decommissioning in 2019.

BKW is also required to upgrade the emergency cooling pumps at the plant, as well as install a new emergency reactor cooling water system and reinforce the emergency cooling system for the used fuel pools. The company had earlier said that, by implementing these measures, it will exceed the safety margin stipulated by ENSI.

Commenting on the regulators final order, ENSI deputy director Georg Schwarz said, "This will ensure that the Mühleberg nuclear power plant will still have a good level of safety up to the end of 2019."

Researched and written
by World Nuclear News