7 Jul (NucNet): France’s nuclear regulator ASN (Autorité de Sûreté Nucléaire) has asked Areva NC to increase its oversight of evaporators at the La Hague nuclear fuel processing facility in northern France after greater levels of corrosion than expected were discovered earlier this year.
In February 2016, ASN asked Areva NC to increase its supervision of the units and install isolation facilities and advanced detection systems to limit the consequences of a leak or rupture.
ASN has now imposed a number of additional measures, including asking Areva NC to define the criteria that would necessitate permanent shutdown of the evaporators, such as the minimum thickness of their walls.
ASN said Areva NC must strengthen controls and checks on the thickness of the evaporator walls. There should be increased monitoring of maintenance shutdowns and plans must be prepared to deal with any emergency resulting from the development of a hole in an evaporator.
Results of all tests must be compiled in reports to be sent to ASN twice a year, ASN said.
The evaporators were commissioned between 1989 and 1994 and designed for an operating lifetime of 30 years. They are used to increase the concentration of fission products in liquid waste produced from processing. This liquid is highly radioactive.
The evaporators are in the UP3-A processing plant, which has an annual processing capacity of around 800 tonnes of used nuclear fuel.
According to Areva NC, La Hague has an overall capacity for the annual processing of used fuel from 80 to 100 nuclear reactors, amounting to 1,700 tonnes. This makes Areva NC the biggest operator in the world in the processing of used nuclear fuel.