Round of upgrades for Swiss nuclear plant

27 July 2011

The Leibstadt nuclear power plant is to have its circulation system upgraded by Areva to help it use nuclear fuel more effectively. A turbine retrofit has already been carried out and some post-Fukushima improvements are to come.


Leibstadt features a boiling water reactor built in the early 1980s. Coolant water is constantly pumped through a large system of piping to remove heat from fission reactions in the core, in the process being formed into a steady flow of steam to drive a turbine-generator set.


Areva has said it will "modernize" this primary circulation set-up "to enhance system availability and to use nuclear fuel even more efficiently." This will see an increased circulation rate during the period approaching refuelling, controlled by new variable speed drive controls. At the same time, the plant's analogue reactor power control systems will be replaced with digital versions.


Leibstadt canteen
Leibstadt workers take a break. About 1500 are involved in the plant's 
scheduled outages when refuelling, maintenance and upgrades take place


Preparatory work will start next year with the bulk of engineering to take place during a scheduled refuelling outage in 2015. Areva will also rework some piping to reduce the number of welding seams and shock suppressors in order to simplify routine inspections.


Swiss policy  


In March the Swiss cabinet announced an intention not to allow replacement of the country's five power reactors, which would mean Leibstadt's closure in 2034 as the last of the country's operating reactors.


This has been approved by the lower house, but is thought unlikely to be approved without modification by the upper house, the Council of States. A public referendum may also be required, particularly as nuclear power was approved by public vote as recently as February this year. In all, it may be about three years before Switzerland's nuclear policy is settled.

The plant's most recent outage was extended slightly at 47 days, during which time engineers replaced three low pressure turbines and a transformer to raise generating capacity by 40 MWe.


Separately, Leibstadt managers are to make displays in the main control room fault resistant after the recommendations of a post-Fukushima safety review. This also requires displays to indicate the water level and temperature of the fuel pools in emergency control rooms as well as the main control room. The plant will also be subject to the European Union's stress tests, in which Swiss authorities are participating fully.


The plant produces 1165 MWe for six utilities with various stakes and meets the needs of around 1.1 million people in the north of Switzerland.
Researched and written
by World Nuclear News