* Low natural gas and power prices could shut reactors
* Filtered vents could cost up to $30 million
* Filtered vents would be in addition to hardened vents
By Scott DiSavino
Jan 9 (Reuters) - U.S. Nuclear Regulatory Commission (NRC) staff on Wednesday briefed the commission on its recommendation to require nuclear operators to spend tens of millions of dollars to install filtered vents at more than two dozen reactors.
Energy analysts said the filtered vents recommendation, which was in response to the staff's review of lessons learned from the 2011 Fukushima nuclear disaster in Japan, is just one of several factors that could increase the cost of nuclear power and possibly lead to the shutdown of some older reactors.
Other factors include: the low cost of natural gas from record shale production that has pushed power prices to decade lows and reduced electric revenues; the lack of government action to limit greenhouse gas emissions; states' efforts to lower power capacity prices; and increasingly strict environmental water and other regulations, the analysts said.
At the NRC meeting on Wednesday, the nuclear industry presented its less costly proposals to filter radioactive contaminants out of a reactor's containment structure in the event of an accident.
During the question and answer period, NRC Commissioner William Magwood referred to the industry proposals as a toolbox of several options that would allow plant operators to decide which practices, including the possible installation of a filter, works best to reduce contaminants from their reactor.
The industry said no two reactors were alike so operators should have various options to reduce possible contamination from each site.
The NRC staff, however, recommended that the nation's 31 boiling water reactors with Mark I and Mark II containment types - similar to those damaged at Fukushima - install filtered vent systems. The 104 reactors in the United States provide about 20 percent of the nation's power.
No U.S. reactors have filtered vents, Scott Burnell, a spokesman at the NRC told Reuters, noting the agency's approach to this point has been on ensuring accidents do not occur in the first place.
Many countries in Europe and other parts of the world already require filtered containment systems or are considering the safety benefits of filters since the Fukushima accident, according to an NRC report.
The NRC said the staff has estimated the filtered vents, which could be as large as the trailer on an 18-wheeler truck, could cost about $15 million. Others estimated the equipment could cost $30 million or more.
Preston Swafford, chief nuclear officer at the Tennessee Valley Authority (TVA), told the commissioners that several of the flexible or so called "FLEX" efforts TVA and others in the industry have put in place, such as the addition of bigger portable pumps and generators, would allow operators to filter out more contaminants before they reach the atmosphere in the event of an accident.
Swafford said TVA had already planned to spend about $185 million on Fukushima-related upgrades and studies, adding that the company was studying the benefits of a filter such as the one recommended by the NRC staff.
He said such a filter could cost about $20 million per unit. TVA has three General Electric Co designed reactors with Mark I containments at the Browns Ferry nuclear plant in Alabama.
"This is not a decision making meeting for the NRC. The different parties will present the pros and cons of installing filters. We're basically at the beginning of the process ... and will come away from this meeting with a lot more information," Tom Kauffman, a spokesman at the Nuclear Energy Institute, an industry trade group, told Reuters.
A spokesman at the NRC said the commission had not set a date to decide on the filtered vent issue, but hoped to have something later this year.
In one of its earlier decisions after reviewing the lessons learned from Fukushima, the NRC in March required the operators of Mark I and II reactors to modify or install hardened vents to more effectively and safely release excessive containment pressure after a serious accident.
Mark I containments already have hardened vents and will likely only need to modify their vents to meet the NRC requirements. But the operators of the nation's eight Mark II reactors will have to install hardened vents as they do not exist in that containment type.
The nuclear industry said it had until the end of February to submit plans to the NRC on how they will meet the hardened vent rules over the next two 18- or 24-month refueling cycles.
"If filtered vents are required, that will change everything because the current plans only include hardened vents - not hardened and filtered vents," NEI's Kauffman said.
The NRC said however that the staff's concept would be that the Mark Is and IIs would have two cycles from the issuance of the proposed order to install the filtered vents.