Swiss plants to be retrofitted for better hydrogen control

26 January 2015

All five of Switzerland's nuclear power reactors are to be retrofitted to increase hydrogen control capabilities, according to new requirements set by the country's nuclear regulator ENSI.

In addition, the units will install new equipment to increase safety during severe accidents, ENSI said in a statement.

All Swiss reactors will have passive hydrogen control once passive hydrogen re-combiners have been installed at Gösgen and Leibstadt, ENSI said. Gösgen has already submitted an application for use of the re-combiners and Leibstadt has until March 2016 to do so.

Beznau has to submit plans by the end of the year to improve hydrogen control, while Mühleberg has to develop a way to measure hydrogen as part of a management plan. Mühleberg has an oxygen-free containment, meaning hydrogen explosions at that unit are not possible. Its plan has to be submitted to ENSI before the end of June.

Two months after the Fukushima Daiichi nuclear power plant accident in March 2011, the Swiss government announced that the country's existing reactors would not be replaced after they reach the end of their operational life.

Without cooling water, the cores of units 1, 2 and 3 of the Fukushima Daiichi plant overheated and largely melted in the first three days. Hydrogen generated by this high-temperature process caused explosions in the upper service floors of reactor buildings at units 1 and 3. Unit 4 had not been operating, but was affected by a hydrogen explosion due to gas back-flow from unit 3.

Researched and written
by World Nuclear News