Double header for Beznau

Thursday, 22 September 2011

The two reactors of Switzerland's Beznau nuclear power plant are set for major maintenance work in 2014 involving new reactor vessel heads as well as other improvements.

 

Westinghouse was the original supplier of the pressurized water reactors and was selected to supply new vessel heads two years ago. A $35 million contract announced yesterday will have it perform the installation during 40-day extended outages in 2014.

 

This will require plasma-cutting through each reactor's concrete and steel containment and removing the old vessel heads to an on-site radioactive waste management building. The new heads, as well as new control rod drives, will then be fitted.

 

A cutaway of the identical Beznau reactors. Click to enlarge (Axpo)

 

During the same outages Westinghouse said it will also be providing two new emergency power buildings with related systems and installing new plant computers.

 

Plant owner NOK said in 2009 that the vessel heads showed no sign of deterioration, but that the experience of more than 80 similar plants around the world was that more regular inspection would begin to be required after about 40 years of operation. Avoiding this extra work was one benefit of the preventative maintenance project.

 

The two 365 MWe reactor at Beznau are the oldest in Switzerland, starting operation in 1969 and 1972. In addition to providing power, they also produce 80 MW in district heating for 11 nearby towns.

 

Swiss nuclear policy is currently a matter of debate, the cabinet having moved to prevent the construction of new nuclear power plants. The eventual text of a new nuclear policy remains to be agreed by the National Council and the Senate, with more input to come from the cabinet in a process that could take years. In the meantime, plans for new reactors at Beznau and Muhleberg have been shelved and the Beznau units remain set to operate until 2019 and 2021 respectively.

 

In an early post-Fukushima safety review, the Swiss Federal Nuclear Safety Inspectorate concluded that the earthquake-resistance of the fuel storage building at Beznau "is in need of improvement," as the fuel pool is not sufficiently protected against earthquakes and flooding. It found that the emergency measures to restore cooling after quakes and flooding "are incomplete." Further recommendations may come from the program of stress tests, led by the European Union, but in which Switzerland is participating. Plant operators will be able to make the required improvements during normal cycle of operation and outage.

 

Researched and written

by World Nuclear News