Recent media reports accusing the nuclear energy industry of opposing the installation of filtered vents on Mark I and II boiling water reactors (BWRs) are incorrect. What is really at stake is taking the most meaningful steps at nuclear plants to prevent and manage an accident like the one at Fukushima.

The nuclear energy industry continues to learn a great deal about what happened at Japan’s Fukushima Daiichi nuclear power plant on March 11, 2011, and is applying the lessons to make America’s nuclear plants even safer.

Commercial nuclear power plants in the U.S. must be able to prevent and manage an accident like the one at Fukushima.

Clearly, the best way is to not have an accident in the first place.  As documented in a report by an independent commission of Japan’s national legislature, U.S. plants are much better regulated, run and prepared than their counterparts in Japan.  In addition to the myriad systems installed in U.S. plants to prevent accidents and cope with a severe accident, U.S. plants have become even better prepared since the Fukushima accident.  Even if all installed cooling systems were to fail, new portable power and water systems will cool the reactor core and protect spent uranium fuel in storage pools at the facility.  These new systems—part of a new diverse and flexible safety strategy (FLEX)—also include additional pre-staged pumps, generators, and other equipment at other nuclear plants and two new regional response centers.

But, what happens if these measures don’t prevent a meltdown?  The image of Fukushima that sticks with many people is the explosions at three of the plant’s buildings. These explosions were later found to be caused by a buildup of hydrogen, which was produced as uranium fuel overheated but was not released by plant operators from the reactor containment by the installed venting system.  Instead, hydrogen collected in the buildings surrounding the containment structures, where it mixed with oxygen in the air and was ignited.

Excess pressure in the reactor containments also resulted in radioactive releases (mostly not via the vent) that contaminated the surrounding area.  However, evacuations due to the tsunami warning and Tokyo Electric Power Co.’s emergency response plans effectively relocated nearby residents prior to the release of radiation.

Based on lessons learned from Japan, the U.S. Nuclear Regulatory Commission (NRC) ordered 31 reactors with the same basic design as those at Fukushima to install hardened vents that could be used to release the buildup of hydrogen and other gases.

In the extremely unlikely event that an accident progresses to the point of the fuel melting through the reactor vessel onto the containment floor, it is imperative that water be injected into containment to cool the fuel debris on the floor.  If not, radiation releases will occur from numerous locations in the containment building and bypass the vent.  If the vent is bypassed, it doesn’t help if there is a filter on the vent, because it, too, will be bypassed.

Last November, the NRC staff issued a policy paper recommending that the commission also approve the installation of external filters on boiling water reactors.

The external filters favored by the NRC staff are large tanks partially filled with water that are located outside the containment building.  Gases that are moved from the containment building using the vent system are released through the water, which filters the radionuclides.

The decision on filters is pending before the five NRC commissioners.

Is there a better solution? Yes.

One approach marries the need to cool the uranium fuel debris by injecting water into the containment building with filtering radioactive material from the vent gases with that water.

A September 2012 report by the Electric Power Research Institute (EPRI) evaluated several potential radiation filtering strategies and assessed their abilities to avoid radiation releases.  The report emphasized the need to cool the fuel debris during a severe accident.  Otherwise, the melted fuel will rupture containment and releasing radioactive materials into the environment bypassing the vent and any filter that might be installed.

Ensuring core cooling this way has the added benefit of “filtering” radioactive material inside the containment building.  The water in containment would work the same way that it would in an external filter.  Thus, keeping damaged fuel cool through the injection of water, with its inherent filtering capability, challenges the basis for compelling external filters at 31 reactors.

This is not a new concept.  In the late 1980s, when the NRC wanted the BWR Mark I plants to add containment vents to prevent over-pressurization during an accident, the vents were piped through the internal suppression pools (water already in containment as part of the existing design to cool and reduce the pressure of the containment atmosphere during accidents).  NRC staff reviews dating back to 1993 stated that an “external filter would not significantly increase the removal of radioactive material….”

In light of the significant body of research on this issue, the industry has recommended that the NRC consider less-prescriptive filtering strategies. Consistent with the EPRI research, filtering strategies focus primarily on providing additional ways to get water to the fuel during a severe accident and to control pressure in containment.  Rather than a prescriptive solution like external filters that has limited benefit and may not provide for additional water to cool the core, the industry envisions that each company would assess the issue on a site-by-site basis and develop an approach that best suits each site.

As pointed out numerous times industry testimony and letters to the NRC, filtering strategies based on the individual plant evaluations could result in the installation of a vent filter if that’s what makes sense for a given plant.

Even the NRC’s Advisory Committee on Reactor Safeguards — an independent body that reviews NRC staff activities and provides independent recommendations to the Commission – supports the proposal to look at performance-based solutions at each reactor.

Filtering strategies will require plant upgrades.  The nature and ultimate cost of those upgrades will depend on the result of the commissioners’ vote on the NRC staff recommendation.  These upgrades will involve making sure that cooling systems can put water in containment to cool the fuel debris and filter radioactive material when and where needed.

Adding this additional layer of safety is the right thing to do, but the industry must have the necessary flexibility to take the right steps based on the unique characteristics of their facilities.

It’s not about the money.  The Fukushima Daiichi accident reinforced the fact that no one can predict Mother Nature. We expect the unexpected and prepare beyond it, to ensure the swiftest and safest response to protect the public and the environment. That’s why we are constantly reviewing and improving the technology and systems we have in place to ensure we have backups to every backup, and practiced emergency response plans for the most extreme situations.

This issue is about providing yet reliable methods to cool the fuel debris by injecting water into containment and filtering the radioactive material from the vent gases with water inside the containment building.

The following article was written by Jason Zorn and Steven Kraft of the Nuclear Energy Institute. Zorn is NEI’s assistant general counsel. Kraft is senior technical advisor.

Representatives of the nuclear energy industry once again this week asked the NRC to adopt a performance-based approach to minimize the release of radioactivity from damaged fuel in a severe accident, while agency staff reiterated its earlier recommendation to require external filters for the containment vents of early-model boiling water reactors.

“A performance-based approach to filtration provides the greatest overall improvement in plant safety with sufficient filtration,” said Maria Korsnick, Constellation Energy Nuclear Group’s chief nuclear officer and chief operating officer. “The industry approach has the advantage of retaining the filtered radionuclides in containment. The desire is to prevent land contamination.”

Korsnick added that a performance-based approach that would specify results rather than methods to attain them would require plant-specific analyses. She noted that the NRC’s independent Advisory Committee on Reactor Safeguards “supports this approach”.

NRC staff told the commissioners it believed filtered vents should be required for boiling water reactors with Mark I and II containments, similar to those involved in the 2011 accident in Japan.

“There is general agreement of all stakeholders that filtration is important to mitigate potential radioactive releases,” said Bill Borchardt, executive director for operations at the NRC. “However, it’s the staff’s view that it is prudent to require the installation of [external] filters on the containment vents.”

Preston Swafford, chief nuclear officer at Tennessee Valley Authority, said he agrees with the industry position as put forward by Korsnick, adding that his organization is conducting analyses on the effectiveness of filtered vents.

“We are supporting Maria and the industry on [the performance-based approach to filtering],” Swafford said. “A dry filter … might be of value. We haven’t concluded one way or another yet, but there may be some additional coping time that filter would give us. We have to finish that [analysis].”

NRC Chairwoman Allison Macfarlane asked whether the decision to manually vent containment during an accident would be easier for operators to make if they knew the vent had an external filter.

“I feel very confident that operators would vent containment as necessary. I don’t think a filter changes that, quite frankly,” Korsnick said.

Neil Wilmshurst, vice president and chief nuclear officer at the Electric Power Research Institute, gave a technical explanation of the performance-based approach. He said that a performance-based filtration strategy should target a 1,000-fold reduction in the amount of fission products released, also known as a decontamination factor of 1,000.

According to a recent EPRI analysis, that level could be reached using a combination of strategies. These would include spraying or immersing damaged fuel within the containment, along with a specifically designed hardened vent that could reliably open and close at appropriate times. This combined approach would not necessarily require a filtered vent.

“A [decontamination factor] of 1,000 is the benchmark we set in our analysis,” Wilmshurst said. “If utilities can come to a position of spraying and flooding and have a controlled reliable, hardened vent, our analysis shows that DFs of over 1,000 can be achieved without a filter.”

Wilmshurst added that the performance-based approach would require site-specific analyses and that filters may play a role in certain scenarios.

“[The EPRI analysis] doesn’t mean filters might not be needed in certain circumstances,” he said. “This is a generic analysis. Specific plant evaluations would be required.”

The five-member commission is continuing its study of filtering strategies and will likely vote on the matter in the near future.

Slides and the meeting agenda are on the NRC website, and an archive of the webcast video is available on the agency’s webcast portal.

Earlier today, the Nuclear Energy Institute released a five-minute video explaining the comprehensive and tailored response strategy that it is implementing across the industry to enhance nuclear plant safety in the face of extreme natural events.

To produce the high-definition video, NEI acquired first-of-its kind footage of the deployment of new emergency response equipment at U.S. nuclear energy facilities. The video also features animation and interviews with industry leaders and technical staff discussing nuclear plant safety.

The diverse and flexible (“FLEX”) response strategy developed by industry addresses the major challenges encountered at the Fukushima Daiichi power station following the March 11, 2011, earthquake and tsunami: the loss of power to maintain effective reactor fuel cooling.

Additional on-site portable equipment is being acquired to help ensure that every U.S. nuclear energy facility can respond safely to extreme events, no matter what the cause. The equipment ranges from diesel-driven pumps and electric generators to ventilation fans, hoses, fittings, cables and satellite communications gear. It also includes support materials for emergency responders. For additional information concerning how the American nuclear energy is applying lessons learned from Fukushima, please visit the Fukushima response section of NEI.org.

Industry/Regulatory/Political

• U.S. Nuclear Regulatory Commission staff has recommended requiring engineered filters to the containment vents for Mark I and Mark II boiling water reactors as a post-Fukushima response. A staff paper released this week for the commission’s consideration said an alternative performance-based approach to filtering preferred by industry and by the NRC’s Advisory Committee on Reactor Safeguards would work but take too long to implement.
• Japan’s pro-nuclear energy Liberal Democratic Party won a landslide victory Dec. 16, taking 294 of the 480 seats in the lower chamber of parliament, despite voters’ relatively negative view of nuclear energy. A poll by the Japanese national newspaper Asahi Shimbun found that 16 percent of voters want to scrap nuclear energy immediately, 28 think it should be phased out and 15 percent support continuing to use nuclear energy. The newspaper concluded that voters did not consider nuclear energy a key issue in the race.
• Japan Atomic Power Co. rejected the finding of the Nuclear Regulation Authority (NRA) that its facility in Tsuruga sits on a newly discovered active fault line. The company said it would sponsor its own seismic study to confirm that it does not. Regulatory authorities can order the plant closed if it is correct.
• The NRA said it would set a standard that’s tighter than that of the International Atomic Energy Agency (IAEA) to determine when to evacuate local residents following a nuclear accident. It said it would evacuate people within a radius of 5 to 30 kilometers [3.1 to 18.6 miles] if radiation levels reached 500 microsieverts per hour rather than the 1,000 microsievert-level set by the IAEA.
• The International Atomic Energy Agency will establish a base in Fukushima prefecture to provide training and emergency equipment that could be used in nuclear accidents in Asia. The base may open as soon as next year. It will be the first IAEA base outside its headquarters in Vienna.

Media Highlights

• Bloomberg reports that Tokyo Electric Power Co. led a surge in the stocks of Japanese power utilities after the Liberal Democratic Party won a landslide election victory. TEPCO jumped 33 percent, leading a 9.3 percent gain in the Topix Electric Power and Gas Index.

Upcoming Meetings

• The NRC will provide an update on activities related to Fukushima task force recommendations 4 (mitigating strategies/FLEX) and 7 (used fuel pool instrumentation and makeup capability) Dec. 17.

This is the last issue of the Fukushima Update. As the situation in Japan has stabilized, the focus in this country has shifted to implementing lessons learned from the nuclear accident. News related to Japan’s response to the event will appear periodically in NEI’s online member publication Nuclear Energy Overview.

NRC staff has recommended requiring engineered filters to the containment vents for early-model boiling water reactors as a post-Fukushima response.

A staff paper (SECY-12-0157) released this week for the commission’s consideration said an alternative performance-based approach to filtering preferred by industry and by the NRC’s Advisory Committee on Reactor Safeguards would work but take too long to implement.

The commission had directed agency staff (SRM-SECY-11-0137) to consider whether adding external filters at the same time as reliable hardened containment vents for Mark I and II boiling water reactors would help limit significant radiation releases from severe accidents.

The staff response said the option to require the installation of vent filters “would provide the most regulatory certainty and the timeliest implementation.”

The staff paper noted that quantitative considerations alone did not demonstrate that the benefits would exceed the costs of its recommended approach. However, it said if qualitative factors such as the importance of the containment function within the NRC’s defense-in-depth philosophy were included, its recommendation for external filters could be justified.

The staff also considered an option for a more comprehensive strategy to maintain cooling and control containment pressure that would combine the use of installed equipment, operator actions and improvements to plant-specific severe accident management guidelines. The industry considers this combined approach the most effective way to reduce radiation releases in extreme situations where reactor fuel may be damaged and consistent with the diverse and flexible “FLEX” coping strategy that is being implemented at every nuclear energy facility.

Steven Kraft, NEI’s senior technical adviser, said the industry believes that use of filters may be unnecessary. In addition, because the filters would be external to the containment building, the radioactive particles generated during an accident would not remain trapped in containment.

The industry’s comprehensive filtering strategy was developed by the Electric Power Research Institute. A report released by EPRI in September said, “Combining containment sprays or immersion of damaged fuel with a specifically-designed vent that can reliably open and close at appropriate times would provide a more than 1,000-fold reduction in the amount of fission products released” (see Nuclear Energy Overview, Oct. 1).

EPRI also commended the industry’s FLEX strategy, observing that “the best way to avoid radiological release and potential land contamination is to prevent an accident from occurring by improving and augmenting the strategies for preventing core damage.”

The NRC’s Advisory Committee on Reactor Safeguards concurred with the industry’s filtering approach. The ACRS said it preferred more general “performance-based standards” that would give plant operators scope to decide on innovative strategies to mitigate radiation releases, while allowing for the alternative technologies and procedures to be measured against objective outcome-based criteria (see Nuclear Energy Overview, Nov. 15).

The staff paper acknowledges that the industry approach is “consistent with NRC policy to encourage the use of performance-based requirements.” However, it said it was recommending vent filters because the combined strategy would “involve a longer-term effort” to complete a rigorous regulatory analysis including a cost/benefit assessment to comply with the agency’s backfit rule. The staff also said the performance-based approach “would likely extend the resolution of this issue by several years,” which it believes runs counter to the commission direction to consider the filtering issue “without delay,” along with the reliable hardened vent issue.

The NRC staff is also recommending that the reliable hardened vents ordered for Mark I and II containments be upgraded to vents that will operate following a severe accident.

NEI’s Kraft said that the NRC staff’s concern about the length of the effort is largely misplaced. Many of the questions the staff appears to have about the filtering strategies option also apply to the use of external filters, he said. For example, injecting water into containment to cool a damaged core is needed in all cases, including if an external filter is installed.

Kraft added, “The industry looks forward to continuing to work with the NRC and other stakeholders to identify the most appropriate way to retain radioactive material inside containment following a severe accident that damages the nuclear fuel and on scheduling and timeline issues related to the regulatory analyses required for a performance-based approach.”

The commissioners will be briefed by the industry, other stakeholders and the staff on Jan. 9. NRC spokesman Scott Burnell said the commissioners are expected to vote on the staff’s recommendations sometime in January.

Industry/Regulatory/Political

• Japan’s Nuclear Regulation Authority said Monday that its survey of a second fault zone directly beneath one of two reactors at the Tsuruga nuclear energy facility in Fukui prefecture found it likely to be seismically active. NRA Chairman Shunichi Tanaka said that, given the results, “there is no way we can carry out safety assessments for a restart.” The NRA team said reactor 2 may have to be decommissioned by the plant operator, although the agency only has the authority to bar the plant from restarting.

• A magnitude 7.3 earthquake occurred Friday off the coast of northeastern Japan, in almost the same area that was hit by a magnitude 9 quake and tsunami on March 11, 2011. Small tsunami waves were recorded at three locations, reaching a maximum height of about three feet. Japan’s nuclear regulator confirmed there was no damage to nuclear energy facilities in the area, including Tokyo Electric Power Co.’s Fukushima Daiichi and Daini, Tohoku Electric Power’s Higashidori and Onagawa plants, Japan Atomic Power Co.’s Tokai Daini, and the fuel cycle complex in Aomori prefecture.

• A preliminary assessment of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) that there are no observable health effects from the Fukushima accident is expected to be endorsed by the UN. The report was approved by the UN General Assembly in September.

Media Highlights

• Japan’s Environment Ministry reported the country’s carbon emissions rose by 3.9 percent in the year following the Fukushima Daiichi accident, during which all but two of the country’s 50 reactors were shut down, said a Bloomberg article. Japan had committed to reducing its emissions by 6 percent from 1990 levels in the period from 1998 to 2012 and actually achieved a reduction of 9.2 percent by 2011, the report said.

• The Japan Times reports that the Nuclear Regulation Authority could begin preliminary safety checks of idled nuclear reactors by the spring, using a draft of new safety standards that are expected to be finalized by July. The inspections could pave the way for some reactors to restart by the summer.

• Kyodo News notes that the NRA has decided to appoint three prominent international nuclear experts as external advisers—former NRC Chairman Richard Meserve; Andre-Claude Lacoste, former chairman of France’s nuclear safety authority; and Mike Weightman, the head of Britain’s nuclear regulation office.

Upcoming Meetings

• The Japanese government and the International Atomic Energy Agency will hold a ministerial conference on nuclear safety in Fukushima prefecture Dec. 15-17. The meeting’s main objective is “to contribute to strengthening nuclear safety worldwide.”

The NRC has issued its final interim staff guidance describing one acceptable method for conducting integrated assessments of external flooding hazards at nuclear energy facilities. The guidance is intended for use in cases where a re-evaluation of the flooding hazard exceeds levels defined by the utilities’ flooding design basis.

The new guidance, JLD-ISG-2012-05, is the latest in a large volume of work the NRC staff is developing to address lessons learned from the 2011 reactor accident in Japan. Interim staff guidance clarifies issues that are not addressed in the standard review plan for nuclear energy facilities.

Last March, the NRC issued three orders and a detailed request for information based on issues or questions raised by the accident, which occurred after a tsunami struck the Fukushima Daiichi nuclear energy facility. The orders required mitigation strategies for severe events that exceed design parameters, enhanced instrumentation for used fuel pools, and reliable hardened containment vents for some reactors. The NRC also required companies to provide detailed information on seismic and flooding hazards and emergency communications systems.

The flood-related portion of the NRC’s request calls for licensees to use the latest available information and methodologies to analyze site-specific hazards, including stream and river flooding, hurricane storm surges, tsunamis, and dam failures. This re-evaluation will determine whether the hazard exceeds the facility’s flooding design basis. If it does, the licensee must perform an integrated assessment for external flooding.

The integrated assessment must consider all modes of plant operation that could be affected by a flood, including shutdown, and take into account other events that could reasonably be expected to occur at the same time as a flood. When licensees report the results of these assessments to the NRC, they must outline the measures that have been taken or are planned to deal with the re-evaluated flooding hazard.

For licensees that must perform an integrated assessment, their report is due to the NRC within two years after submittal of their flooding re-evaluations.

The final guidance can be found on the NRC’s ADAMS document tracking database under ML12311A214.

A 7.3 magnitude earthquake struck Japan overnight, triggering tsunami warnings across the island nation. The warnings were lifted soon after and the quake caused very little damage.

We’ve got out eyes on the situation at Fukushima Daiichi, and things there look quiet according to ABC News: “No damage has been reported at monitoring posts and water treatment facilities at the reactors … All the workers were moved to higher ground on the site and told to stay inside after the tsunami warning.”

Industry/Regulatory/Political

• Japan’s Nuclear Regulation Authority last week began examining a fissure beneath Japan Atomic Power Co.’s Tsuruga nuclear energy facility in Fukui prefecture to determine whether it is associated with a nearby active fault. NRA officials investigated samples of rock strata extracted in a field survey. If the agency decides that the plant is located above an active fault, the facility’s two reactors are unlikely to be allowed to resume operation. The agency is expected to finalize its assessment after a Dec. 10 meeting. Several other reactors are slated for similar investigations. A separate team last month failed to reach a definitive conclusion about Kansai Electric Power Co.’s Ohi site, where Japan’s only two operating reactors are located.

• The Japan Atomic Energy Commission submitted a draft proposal to the government suggesting that plans for the “semi-permanent” burial of high-level radioactive glass waste from the reprocessing of used nuclear fuel be revised to allow for retrieval of the waste if more stable disposal areas or better disposal methods are discovered in the future. The JAEC report also said the government should quantify the total amount of waste that would be generated if it limits the operating lifetimes of nuclear reactors to 40 years and bans new reactors.

Plant Update

• Tokyo Electric Power Co. plans to speed up the removal of used nuclear fuel from the Fukushima Daiichi reactor 4 storage pool. The removal is scheduled to begin in November 2013, a month earlier than originally planned, and to be completed December 2014, one year earlier than planned. TEPCO said it will accomplish this by increasing the number of steel containers used to store the fuel after its removal from the pool.

Media Highlights

• The Mainichi reports that Japan has not retracted its Kyoto Protocol goal to reduce carbon emissions by 25 percent of 1990 levels by 2020, even though it has not explained how it expects to meet the target with most of its nuclear capacity idled. The U.N. Framework Convention on Climate Change kicked off discussions last week in Doha, Qatar, on measures to recommit developed nations to a second period of the Kyoto Protocol, which expires at the end of the year. The Yomiuri Shimbun notes that Japan’s Environment Ministry has criticized Tokyo Electric Power Co.’s plans to buy electricity from coal-based “independent power producers” because of the increased carbon emissions that would result.

• A senior official of the opposition Liberal Democratic Party said last week that Japan must quickly restart its idled nuclear reactors “once their safety has been confirmed,” an article by Bloomberg News said. The LDP is considered likely to lead a coalition back to power after December’s general election.

• The Japan Times reports on a preliminary paper released last week by the World Health Organization, which says that cancer risks in the vicinity of Fukushima Daiichi are expected to be low.

Upcoming Meetings

• The Nuclear Energy Institute holds its Fukushima Regulatory Response Workshop in Washington, D.C., on Dec. 3-4. The workshop will focus on implementation of the industry’s FLEX strategy.

• NRC staff meets with the agency’s Advisory Committee on Reactor Safeguards Dec. 4 to finalize its options for creating a more integrated regulatory framework as was recommended by the post-Fukushima task force.

• The Japanese government and the International Atomic Energy Agency will hold a ministerial conference on nuclear safety in Fukushima prefecture Dec. 15-16. The meeting’s main objective is “to contribute to strengthening nuclear safety worldwide.”