5 Jun (NucNet): Hitachi-GE Nuclear Energy and Areva have said they will work together to install filtered containment venting systems (FCVS) at boiling water reactors (BWRs) in Japan.
The companies said in a joint statement that since the March 2011 Fukushima-Daiichi accident Hitachi-GE has stepped up its efforts to improve the safety of nuclear power plants, and Areva has already installed FCVS in more than 50 plants worldwide.
Hitachi-GE has been working with Areva to study the functions and performance of FCVS suitable for installation at BWR nuclear power plants in Japan.
An agreement announced yesterday means the two companies will work together on the adoption by Hitachi-GE of Areva technology for the design, fabrication, and installation of FCVS.
According to Areva, FCVS play an important role in preventing damage to primary containment vessels due to pressure rises in situations where severe damage has occurred to the reactor, such as following an event that goes far beyond the design basis event criteria.
FCVS is also a filtering system for removing the radioactive material throughout different high efficient filter stages.
In a memorandum issued in March 2012, the US Nuclear Regulatory Commission said operators at Fukushima-Daiichi were unable to successfully operate the containment venting system during the early part of the accident. The inability to reduce containment pressure inhibited efforts to cool the reactor core.
“If additional backup or alternate sources of power had been available to operate the containment venting system remotely, or if certain valves had been more accessible for manual operation, the operators at Fukushima may have been able to depressurise the containment earlier,” the NRC said.
“This, in turn, could have allowed operators to implement strategies using low-pressure water sources that may have limited or prevented damage to the reactor core.”
The NRC said the events at Fukushima-Daiichi showed that reliable hardened vents at BWR facilities with Mark I and Mark II containment designs are important to maintain core and containment cooling.
Hitachi-GE “has been involved with 23 reactors in Japan to date including those under construction”, yesterday’s statement said. Among them, it has been part of all of Japan’s Advanced Boiling Water Reactor (ABWR) projects. Four ABWRs are operational – although offline for safety checks following the Fukushima-Daiichi accident – and three are under construction.
Areva will also equip the Japanese pressurised water reactor (PWR) fleet with more than 100 of its passive autocatalytic recombiners (PARs), which are safety devices used to prevent the build-up of hydrogen into reactor containment and to preserve the integrity of reactor buildings and components.
PARs do not require any operator intervention or power and continue to work even in the event of a station blackout, Areva said. The devices are easily installed, and generate almost no operational or maintenance costs because they use a catalytic oxidation process to convert hydrogen gas into harmless water vapour.
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