LIMERICK — In an effort to prevent an explosion at nuclear plants with reactor designs similar to the one at the Fukushima nuclear plant in Japan two years ago, the government is requiring further improvements at some American nuclear plants, including the Limerick Generating Station.
Specifically, the Nuclear Regulatory Commission voted 3-2 on March 19 to require 31 boiling water nuclear reactors with Mark I or Mark II containment system designs to improve their venting systems to keep pressure from escaping hydrogen from building inside the containment building and exploding, as occurred in Japan.
The Fukushima Daiichi disaster occurred in March, 2011 when a tsunami, caused by a 8.9 level earthquake off the coast of Japan, flooded the plant knocking out power to cooling pumps and leading to explosions and massive radiation releases.
However, as The New York Times reported, although the vent decision is meant to prevent the build-up of pressure, temperature and radiation, like at Fukushima, “the agency stopped short of requiring filters to scrub out radioactive particles coming through those vents.”
The staff must consider both the use of filters and other approaches to achieving the goal of preventing the release of radiation during an accident.
Since the Fukushima disaster, the NRC has ordered hundreds of safety upgrades, most of which have been embraced by the nuclear industry.
However one area of resistance has been the question of requiring filters, which would cost the industry as much as $45 million.
The filters, which are supposed to prevent radioactive particles from escaping into the atmosphere and which are required in Japan and much of Europe, have been recommended by the staff of the regulatory commission.
But, as the Times has reported, the industry has held private meetings with commissioners and their staffs, “and helped line up letters of support from dozens of members of Congress, many of whom received industry campaign contributions” against the requirement.
On March 7, NRC Chair Allison Macfarlane wrote to Massachusetts congressman Edward Markey in support of using filters, but the majority of the commission voted against focusing on that approach alone, opting instead to allow filters to be just one of several approaches considered for a staff recommendation.
“The debate over the filters reflects a simmering tension that has been building inside the regulatory agency since the Fukushima accident in Japan. A tug of war among commissioners and between some commissioners and staff members has produced repeated votes that reject staff safety recommendations,” the Times reported in February.
In 2011, former NRC chairman Gregory Jaczko resigned after the other four commissioners complained to the White House that Jaczko was cutting them out of the loop on plans for the industry’s response to the Japanese disaster.
Jaczko, responded that, “unfortunately, all too often, when faced with tough policy calls, a majority of this current commission has taken an approach that is not as protective of public health and safety as I believe is necessary.”
Some action has been taken however.
In March 2012, the NRC ordered that reactors with containment design similar to Fukushima, including Limerick, “harden” their venting systems.
“‘Hardened’ means these vents must withstand the pressure and temperature of the steam generated early in an accident. The vents must also withstand possible fires and small explosions if they are used to release hydrogen later in an accident. The vents must be reliable enough to be operated even if the reactor loses all electrical power or if other hazardous conditions exist,” the NRC’s blog explained last April.
The most recent order takes that improvement one step further.
“This is the bottom line: the NRC will issue an order requiring stronger venting systems and will use the agency’s rulemaking process to consider the best approach by which these 31 reactors can keep radioactive material from the environment during a severe accident,” NRC public affairs officer Scott Burnell wrote on the NRC blog.
“Some of the U.S. reactors that are similar to the Fukushima Dai-ichi plant have vents that reduce pressure during an accident and keep water flowing to the reactor to cool the fuel. The venting systems at Fukushima played a role in their nuclear crisis, and the NRC, last March, issued an order to the 31 plants with similar designs to take action. The plants either had to install vents or improve their existing venting system. The goal was to make sure the vents can operate during the early phases of an accident, even if the plant lost all power for an extended time,” Burnell wrote.
“Generally speaking, these additional requirements mean the vents could handle the pressures, temperatures and radiation levels from a damaged reactor, and that plant personnel could operate the vents under these conditions,” Burnell wrote.
The NRC staff has 60 days to finalize an order for these enhancements.
Dana Melia, communications manager for the Limerick nuclear plant, said the company supports the decision.
“Exelon fully supports the NRC’s decision to use the rulemaking process to identify the most effective way to reduce radiation releases in extreme situations,” Melia wrote in an e-mail to The Mercury.
“Exelon will spend approximately $400 million across its nuclear fleet over the next four years on Fukushima-related enhancements. Industry efforts to upgrade or install new vents is one outcome of Fukushima lessons learned. At Limerick Generating Station, a conceptual design to install new hardened containment vents has been developed to further improve our safe and reliable operations,” she wrote.
“Like our many stakeholders and industry partners, we want the very best strategy available and we continue to advocate for an effective site-by-site solution,” Melia wrote.
NRC staff now has a year to produce a technical evaluation of the new rule.
“The commission directed the staff to consider both the use of a filter to be placed on the vent, as well as a more performance-based approach using existing systems to achieve a similar reduction in radioactive release during an accident,” according to a March 19 NRC release.
The staff then must develop a draft rule and final rule, all by March 2017.
In addition to Limerick, the rule also applies to reactors at Oyster Creek, Peach Bottom and Susquehanna nuclear plants, according to NRC spokesman Neil Sheehan.
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