US NRC panel does not support mandatory filters at nuclear units

Washington (Platts)--9Nov2012/447 pm EST/2147 GMT

An advisory panel to the US Nuclear Regulatory Commission said Friday it does not support requirements that 31 nuclear units install expensive external filters, saying a more general requirement that the plants improve protection from radiation release would be a better regulatory step.

NRC staff, at a briefing for the advisory panel last week, will formally recommend to commissioners that the external filtered vents be required for the 31 units, which are boiling water reactors similar in design to those that experienced core melting at Fukushima 1 in March 2011.

Commissioners will decide whether to require the vents, which the agency has estimated may cost $16 million each to install, or take different measures after receiving a staff paper outlining options later this month.

The Advisory Committee on Reactor Safeguards, a group of professors, scientists and engineers, said in a letter made public Friday that they supported tougher measures for the 31 reactors, and recommended that existing systems to ventilate the reactors' containment structures be upgraded.

Venting containment is important in nuclear accidents to relieve pressure from heat that can build up in a reactor with fuel damage. The Fukushima 1 accident in Japan "called into question the reliability of current vent systems," especially when power has been lost, the ACRS said in the letter.

Staff had said external filters, which use sand or water to trap radioactive contaminants, should be required for the 31 reactors, which have smaller containment structures than other US nuclear units.

The containment is a sealed structure that surrounds the reactor, safety systems and associated equipment. At Fukushima 1, the containment structures apparently leaked and, when vented, released large amounts of radioactivity.

The ACRS letter said setting performance-based standards could result in utilities installing external filters for vents, but would provide "more scope for innovation and may result in more effective solutions."

The Nuclear Energy Institute, which represents nuclear reactor vendors and operators, said it favored a performance-based approach that would allow utilities to use a series of strategies to minimize radioactivity releases during an accident.

NEI supports the ACRS position, spokesman John Keeley said Friday.

NEI said in a letter to NRC last month that a performance-based standard for mitigating radiological releases in an accident could include flooding containment structures with water and cycling open and shut existing hardened vent systems. Filters cannot scrub the smallest particles from aerosols released through the vents, NEI said.

During a meeting last week, at which NRC staff presented the recommendation to the ACRS, representatives of environmental groups said they support requiring the external filters.

Requiring filtered containment vents for the reactors in question is "a no-brainer," said Mary Lambert, head of the group Pilgrim Watch in Massachusetts. Entergy's 728-MW Pilgrim reactor in Plymouth, Massachusetts, is one of the 31 units that the proposed order would cover.

Requiring the vents would put the US in line with most other countries operating BWRs, said Jim Riccio, a nuclear policy analyst with Greenpeace in Washington.

The new measures, if approved by the commission, would apply to certain models of General Electric-designed reactors.

--William Freebairn, william_freebairn@platts.com
--Edited by Valarie Jackson, valarie_jackson@platts.com