TEPCO announced they will begin installation of a filtered emergency vent system at the number seven unit at Kashiwazaki Kariwa nuclear plant. Concerns were raised after the Fukushima meltdowns as venting needed to prevent a catastrophic containment failure released large amounts of radiation into the atmosphere.
The system TEPCO plans to use involves an 8 meter by 4 meter water tank to filter any venting releases. The current venting systems assume the suppression chamber (torus) will filter venting gasses by being partially filled with water. What was found during the Fukushima meltdowns was that the suppression chamber can be drained of water through a number of processes leaving no water to filter the venting. Venting the drywell directly, releases radiation directly to the environment. Units 1 and 2 at Fukushima Daiichi were both drywell vented during the meltdowns.
While TEPCO has taken steps to begin solving this problem at units that may never be restarted the US power companies are doing everything they can to not install vent filters. US NRC staff have recommended to the commission that US Mark 1 and Mark II reactors should install vent filters. In response the US nuclear industry through their representative to the NRC, NEI has refused to cooperate.
NEI’s stance has been that this simple request needs to be debated and they claim it is too complicated to implement. NEI has previously claimed these GE BWR reactors are each so unique they can’t be asked to install a standard system. The filter system as seen in the TEPCO presentation sits outside the reactor building between the building and the vent stack. This outside design eliminates any supposed unique reactor design excuses made by NEI. The requests by NEI to debate the “pros and cons” of these vents is simply a stalling tactic and sadly even TEPCO has proven more responsive than the US industry. The “every reactor is unique” excuse to not install a somewhat standardized filter system is yet another stalling tactic.
Having to create multiple types of filtration, prove they work and run each one through a unique NRC approval process would take years vs. a much shorter and less resource intensive process of mandating a standardized design for all BWR units. This isn’t a debate about technical implementation it is an issue of the US power companies not wanting to spend the money. The NRC has estimated installing a filter system could cost $15 million or more per unit. The US nuclear industry simply does not want to spend money if they don’t have to and are willing to gamble with public safety. Without a hard fast deadline and a standardized system to install this needed safety mandate it will end up like many other safety rules on US reactors, never done.
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