Search Results for fukushima

NRC Cherry-Picking in the Post-Fukushima Era: A Case Study

Mark Leyse , UCS

In the late 1960s, the Atomic Energy Commission (AEC), the forerunner of the NRC, paid the very companies that designed nuclear reactors—Westinghouse and General Electric (GE)—to test the efficacy of their own emergency cooling systems. Read More

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Fukushima’s Nuclear Safety Dividend at Surry Nuclear Plant

, director, Nuclear Safety Project

On March 11, 2011, a large earthquake with an epicenter a few miles off the northeastern shores of Japan spawned a tsunami that inundated the Fukushima Daiichi nuclear plant. The earthquake disconnected the plant from the offsite power grid. The tsunami disabled the onsite emergency diesel generators. Deprived of electricity for emergency systems, the reactor cores for Units 1, 2 and 3 overheated and melted down.

On March 12, 2012, the Nuclear Regulatory Committee (NRC) ordered owners of US nuclear power plants to develop and implement mitigation strategies to reduce the vulnerabilities of their facilities to extreme earthquakes and floods. While the specific measures varied from plant to plant, the mitigating strategies generally involved portable pumps, portable generators, cables, hoses, and hauling equipment (called FLEX equipment) and associated procedures for workers to use should permanently installed equipment become disabled.

While the NRC’s order and the industry’s FLEX equipment were intended to reduce vulnerabilities to hazards over and above those deemed credible when the nuclear plants were designed and licensed, Dominion Energy has figured out how to use the new equipment to lessen old risks at its Surry nuclear plant, thus reaping a nuclear safety dividend from its Fukushima investment.

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Presentation to NRC Commission on Lessons from Fukushima

, director, Nuclear Safety Project

The Nuclear Regulatory Commission invited me to share UCS’s perspectives on the status of lessons learned from the Fukushima accident during a November 17, 2015, briefing. This briefing was one in a series of briefings conducted every 3-4 months by the Chairman and Commissioners to hear from external stakeholders and the NRC’s senior staff. Read more >

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Four Years after Fukushima: The NRC at a Tipping Point

, senior scientist

Today, on the fourth anniversary of the Fukushima accident, the Nuclear Regulatory Commission (NRC) is on the verge of a major decision that could determine whether or not the types of regulatory errors that set the stage for the accident in Japan will be effectively fixed in the United States. Read more >

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TEPCO’s Fukushima Folly

, director, Nuclear Safety Project

Fission Stories #180

In early August 2014, the Tokyo Electric Power Company (TEPCO) announced that its latest analysis revealed the meltdown of the Unit 3 reactor at Fukushima Daiichi was worse than previously estimated. Read more >

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Initial Comments on NAS’s Report “Lessons Learned from the Fukushima Nuclear Accident for Improving Safety of U.S. Nuclear Plants”

, director, Nuclear Safety Project

On July 24, 2014, the National Academy of Sciences (NAS) released the final pre-publication report  by a committee tasked with reviewing the March 2011 accident at the Fukushima nuclear plant in Japan and its lessons for improving the safety of U.S. reactors. With appendices, the report is over 350 pages long. My colleague Ed Lyman and I have done an early review of the report and have these initial comments, likely to be supplemented as we probe this extensive report further. Read more >

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“Fukushima: The Story of Nuclear Disaster” Book Released

, co-director and senior scientist

Yesterday we officially released our book Fukushima: The Story of a Nuclear Disaster, published by New Press and co-authored by Dave Lochbaum and Ed Lyman, and journalist Susan Q. Stranahan. Susan for many years was a journalist with the Philadelphia Inquirer, and was the lead reporter of the Inquirer’s Pulitzer Prize-winning coverage of the 1979 Three Mile Island nuclear accident. Read more >

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Water Management and Mismanagement at Fukushima

, senior scientist

This photo shows the reactors (right) and the storage tanks for contaminated water (left) at Fukushima Daiichi on March 3, 2013 (Source: Google Earth)

In December 2011, the government of Japan announced with great fanfare that the nuclear reactors damaged in March at Fukushima Daiichi were in a state of “cold shutdown” and that the release of radioactive materials from the reactor containment vessels had been brought under control. Read more >

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Two Years After Fukushima: Status of NRC Safety Reforms

, senior scientist

Following the March 11, 2011, nuclear accident at the Fukushima Daiichi nuclear plant in Japan, the Nuclear Regulatory Commission (NRC) set up a task force to identify the lessons the U.S. nuclear industry should learn from the accident to avoid something similar here. Two years later, where does that effort stand to make U.S. reactors safer? Read more >

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Fission Stories #130: Fukushima’s Dividends or Mea Culpas

, director, Nuclear Safety Project

On March 11, 2011, an earthquake measuring 9.0 on the Richter scale off the coast of Japan spawned a large tsunami wave that overtopped the protective seawall at the Fukushima Daiichi nuclear plant. The flood waters disabled emergency equipment. The three reactors operating at the time of the earthquake experienced extensive damage due to overheating. Read more >

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Lyman Letter Urges NRC to Pursue Post-Fukushima Safety Upgrades

, co-director and senior scientist

Ed Lyman sent a letter today to NRC Chair Allison Macfarlane  urging the NRC to reject recent requests by legislators to weaken critical post-Fukushima safety reforms and slow down their implementation. His letter is responding to recent letters sent to the NRC by Senate and House Republicans complaining that the agency is moving too quickly with costly post-Fukushima safety upgrade requirements. Read more >

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Is NRC Hiding an American Fukushima?

, director, Nuclear Safety Project

The Huffington Post reported on September 14, 2012, that the Nuclear Regulatory Commission (NRC) has known for several years about a flooding threat that could trigger all three reactors at the Oconee nuclear plant in South Carolina to melt down. The Huffington Post’s account included a link to a letter to the NRC’s Inspector General from the NRC’s primary author of a lengthy report on flooding hazards.

In his letter, this NRC staffer alleges that the NRC improperly withheld information about this hazard from the public. Read more >

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Briefing to the NRC on Fukushima Lessons-Learned

, director, Nuclear Safety Project

On Tuesday the Nuclear Regulatory Commission (NRC) was briefed by two panels on the implementation of lessons learned from the Fukushima Daiichi nuclear accident. The first panel consisted of James Scarola of Progress Energy, Casey Pfeiffer of the Professional Reactor Operators Society, Christopher Paine of the Natural Resources Defense Council, and me.

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Lochbaum and Lyman Address NAS on US Response to Fukushima

, co-director and senior scientist

The National Academy of Sciences (NAS) is working on a study called “Lessons Learned from the Fukushima Nuclear Accident for Improving Safety and Security at US Nuclear Plants.” It is currently in the phase of collecting information through public meetings.

Dave Lochbaum and Ed Lyman were part of a small group of people who addressed the NAS panel yesterday. The slides from their presentation are available here.The others addressing the panel were two representatives from the Nuclear Regulatory Commission—Mike Johnson, deputy executive director for Reactor and Preparedness Programs, and Rob Taylor, deputy director of the Japan Lessons Learned Project Directorate—and Marv Fertel, president and CEO of the Nuclear Energy Institute, the nuclear industry trade association.

The NAS website says the report will address the following issues:

1. Causes of the Fukushima nuclear accident, particularly with respect to the performance of safety systems and operator response following the earthquake and tsunami.

2. Re-evaluation of the conclusions from previous NAS studies on safety and security of spent nuclear fuel and high-level radioactive waste storage, particularly with respect to the safety and security of current storage arrangements and alternative arrangements in which the amount of commercial spent fuel stored in pools is reduced.

3. Lessons that can be learned from the accident to improve commercial nuclear plant safety and security systems and operations.

4. Lessons that can be learned from the accident to improve commercial nuclear plant safety and security regulations, including processes for identifying and applying design basis events for accidents and terrorist attacks to existing nuclear plants.

The two-year study is due out in 2014.

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Fukushima Response

, director, Nuclear Safety Project

Tony Pietrangelo, Chip Pardee, me, and Bill Borchardt from left to right (NEI photo).

The Nuclear Energy Assembly was conducted May 21-23, 2012, in Charlotte, North Carolina. Approximately 500 nuclear industry executives from the United States and abroad typically attend these annual conferences. Marvin Fertel, President of the Nuclear Energy Institute, invited me to attend the conference this year and participate in a session titled “The Response to Fukushima.” Tony Pietrangelo, NEI’s Chief Nuclear Officer, moderated the session which also included Bill Borchardt, Executive Director of Operations for the Nuclear Regulatory Commission, and Chip Pardee, Exelon’s Chief Operating Officer.

Tony posed a series of questions to the panel drawing out the measures taken and planned in response to the Fukushima disaster. Bill made the point that the NRC needed discipline to avoid labeling everything as being a Fukushima fix. The NRC developed a process to implement the lessons learned from Fukushima that complements existing processes for resolving other safety and security issues. Bill indicated that these multiple tracks worked best when items did not cross lanes seeking a fast track.

Chip reinforced a point often made throughout the conference about the importance of not allowing the focus on safe performance of operating reactors to get distracted or diluted by the implementation of Fukushima’s lessons.

Tony’s final question sought our views on what a successful response to Fukushima would look like. Earlier discussions questioned whether a 5-year timeframe for complete implementation was viable. I stated that success entails effective implementation without undue delay. Conceding that delay was, like beauty, in the eyes of the beholder, I cited the gas accumulation in safety system piping and components issue (Generic Letter 2008-01, as a good example of the nuclear industry and the NRC working together to resolve a safety issue without undue delay. If the Fukushima lessons can be implemented effectively with no wasted time or inactive periods along the way like in the Generic Letter 2008-01 precedent, it’ll be a success.

Before closing, I wish to express my appreciation to Marv Fertel, Tony Pietrangelo and NEI for including me on this panel. They knew beforehand that my views would not align with theirs and could have easily and justifiably not invited me to the panel. I applaud Marv and Tony for soliciting a broader spectrum of viewpoints.

A video of the panel is available here.

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US Nuclear Power Safety — One Year After Fukushima

, co-director and senior scientist

Yesterday UCS released its report U.S. Nuclear Power Safety One Year After Fukushima, written by Dave Lochbaum and Ed Lyman. It assesses how the Nuclear Regulatory Commission (NRC) and US nuclear industry are responding to the nuclear accident that occurred in Japan on March 11 of last year.

The report points out that this is not an academic exercise since the designs of the Fukushima reactors are similar to many US reactors, and US reactors are also vulnerable to natural disasters or a terrorist attack. The Japanese accident exposed several safety shortcomings that could also affect US reactors.

To its credit, soon after the accident, the NRC set up a task force to review the accident and identify measures to reduce vulnerabilities at US reactors. The task force presented 12 recommendations in July 2011.

Its first recommendation was to clarify the current patchwork of regulatory requirements governing “beyond-design-basis” accidents—that is, accidents more severe than the reactor is designed to withstand. Currently, the NRC regulations governing such accidents are fragmented and uneven—there are some NRC requirements that apply to some types of beyond-design-basis events, but not others. The task force considered this the most important recommendation because it provides a necessary foundation for its other 11.

The NRC later placed all but the first recommendation into three categories of priority:

  • Tier 1 items, which are expected to be handled largely by means of orders issued to plant owners before the first anniversary of the accident, although the plants would not have to fully implement the changes for nearly five years;
  • Tier 2 items, to be addressed through rulemaking within five years of the accident; and
  • Tier 3 items, to be dealt with through means and a schedule to be outlined by September 2012.

However, the NRC decided to move the task force’s top recommendation to the bottom of its priority list—below even Tier 3. Dave and Ed note that this decision “will likely only add more patches to the existing patchwork” and make it harder to implement the other recommendations consistently across all U.S. reactors.

The nuclear industry is responding to Fukushima by proposing the Diverse and Flexible Coping Capability program, or FLEX, under which plant owners are beginning to buy new emergency equipment, ostensibly to better respond to severe natural disasters. Plant owners are dispersing it in numerous locations on and near reactor sites, but are not planning to harden it against natural disasters. The industry is banking on there being enough equipment available so that at least some of it would be usable in the event of an emergency.

But since there are no NRC guidelines yet for what equipment is needed or how it should be protected, this may not ultimately be an effective response if there is an emergency. This may be a case of the industry tail wagging the NRC dog—hopefully the NRC will not be deterred from requiring hardened equipment if that is what its analysis shows is needed to provide adequate protection.

UCS released its own recommendations for improving reactor safety and protecting the public last July. Three of them—enlargement of emergency evacuation zones, expansion of potassium iodide distribution, and accelerated transfer of spent fuel from pools to dry casks—were later chosen by the NRC staff for further evaluation. However, the NRC placed these recommendations into the Tier 3 category, deferring action for an as-yet-unspecified period of time.

Dave and Ed also have an op-ed on

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NRC’s Post-Fukushima Response: Going in Circles?

, senior scientist

One of the most important tasks before the Nuclear Regulatory Commission (NRC) today is moving forward quickly on implementing the safety improvements recommended by its Fukushima Near-Term Task Force, and considering additional safety enhancements that have been identified by the NRC staff.

For a while it appeared that this was actually taking place. Read more >

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Details on Fukushima: Info from INPO

, co-director and senior scientist

Last Friday the Institute of Nuclear Power Operations (INPO) released a detailed timeline of events at Fukushima in the days following the March 11 earthquake and tsunami, titled “Special Report on the Nuclear Accident at the Fukushima Daiichi Nuclear Power Station.”

The report doesn’t seem to break much new ground, but is a nice summary of what is known about those initial days.

INPO is a not-for-profit organization set up by the nuclear industry following recommendations of the Kemeny Commission that investigated the March 1979 Three Mile Island accident.

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Feedback to the NRC on Fukushima Task Force Recommendations

, co-director and senior scientist

Ed Lyman, UCS Senior Scientist, took part in a small meeting with the NRC Commissioners on September 14 to provide comments on the “short-term actions” recommended by the NRC Task Force that was set up following the Fukushima nuclear accident. A panel of experts provided comments on the Task Force recommendations:

  • William Leith, Earthquake Hazards Program Coordinator, U.S. Geological Survey
  • Charles Pardee, Chairman, Industry Fukushima Response Steering Committee and Chief Operating Officer, Exelon Generation
  • Thomas Cochran, Natural Resources Defense Council
  • Ed Lyman, Union of Concerned Scientists
  • Sue Perkins-Grew, Director, Emergency Preparedness, Nuclear Energy Institute
  • Patrick Mulligan, State of New Jersey and Federal Radiological Preparedness Coordinating Committee

Ed’s presentation can be found here.

Following comments by the panelists, the NRC staff made a presentation to the Commissioners on these short term actions.

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NRC’s Path After Fukushima: Still Lined with Pitfalls

, senior scientist

On Friday, August 19, the Nuclear Regulatory Commission (NRC) released its initial response to the recommendations of the Fukushima Near-Term Task Force. The NRC did not address the substance of the Task Force recommendations, but only the process for further evaluating them. The NRC’s response, in the form of a “Staff Requirements Memorandum” (SRM), represents an attempt at reconciling the often differing views of NRC Commissioners.

A core dispute hinged on whether the Commission should vote within 90 days to move forward with any of the 12 recommendations provided by the Task Force, or instead require the staff to analyze the issues further and provide additional opportunities for external input. Chairman Jaczko said there was sufficient analysis at this point to move forward on voting on the recommendations within 90 days, noting that this would be only the first step and that there would be further opportunities for Commission guidance, such as rulemaking proceedings.

A majority of the Commissioners, however, believed that a process should be instituted for NRC staff and external “stakeholders” (e.g., the nuclear industry and non-governmental organizations) to have the opportunity to review, analyze, and comment on the recommendations before the Commission votes on whether to adopt them.

As a result, the majority view prevailed, and in the August 19 SRM the Commission ordered the staff to produce a draft charter to guide the review process, which will involve the creation of a senior-level NRC steering committee. The Commission also required the staff to provide two additional papers after 21 days and 45 days, which would contain further proposals on prioritizing the Task Force recommendations. Each of these papers will have to be voted on by the Commission. In addition, the Commission requested the Advisory Committee on Reactor Safeguards (ACRS) to formally review the Task Force recommendations, as well as the staff’s evaluation and prioritization of the recommendations.

Finally, the Commission segregated the first recommendation of the Task Force from the others and put it on a much slower track, requesting a staff paper in 18 months. This recommendation is an overarching one that would require a change in the Commission’s policy on how “severe” accidents would be regulated. This is a slower track than is warranted. Although this recommendation is not itself an urgent matter, it could facilitate implementation of other recommendations that do address urgent safety matters. Deferring action on this recommendation could therefore be counterproductive in the long run. This is also an issue the NRC has been considering for decades. Six months should be adequate time for the staff to develop a proposal based on this recommendation.

UCS, as a stakeholder in the process, certainly appreciates the interest of the NRC in developing a process to receive input from external groups. For instance, we would like the NRC to give due consideration to our own recommendations for strengthening nuclear safety, which contain some elements not addressed adequately by the Task Force.

However, UCS does not wish to see a repeat of the NRC’s sluggish response to the 9/11 attacks. In that case, even though the NRC issued a series of orders known as “compensatory measures” in February 2002 to quickly address security vulnerabilities that became apparent after 9/11, the NRC and the Nuclear Energy Institute (NEI), which was representing the nuclear industry, did not even come to agreement on what the orders meant or how they should be implemented until nearly five years later. The guidance was not fully implemented at all plants for five and a half years, and the NRC did not complete its inspections until December 2008—nearly six years after the orders were issued. NEI’s role in this delay is a demonstration as to why “stakeholder” input into regulatory processes is not always beneficial.

UCS believes that many of the Task Force’s recommendations for near-term action, such as addressing gaps in the protection of nuclear plants against natural disasters, can and should be approved quickly with a minimum of additional analysis. The process as outlined in the NRC’s Staff Requirements Memorandum will not necessarily conflict with this goal, but it will all depend on the staff’s plan as approved by the Commission. The Commission should not create a process that allows for open-ended negotiation with NEI on every technical and regulatory issue.

Coming four days after the SRM was issued, the August 23 earthquake in Mineral, Virginia should be a further call to action for NRC. That magnitude 5.8 earthquake caused ground motion that exceeded the “design basis” at the nearby North Anna nuclear plant, even though Dominion, the plant operator, originally had said the plant was designed to withstand an earthquake of magnitude 5.9-6.2.

This event highlights the knowledge gaps in seismic protection at US nuclear plants and supports the Task Force’s recommendation that the NRC should “order licensees to reevaluate the seismic and flooding hazards at their sites against current NRC requirements and guidance, and if necessary, update the design basis and SSCs [structures, systems, and components] important to safety to protect against the updated hazards.”

The American public deserves swift action—before the next surprise hits—to address safety problems that have been allowed to fester unresolved for too long.

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UCS’s Take on NRC’s Post-Fukushima Recommendations

, co-director and senior scientist

Today we released our critique of key recommendations by the Nuclear Regulatory Commission’s (NRC) near-term task force in response to the Fukushima Dai-ichi nuclear accident earlier this year.

Three of the five NRC commissioners have now voted to not put its own task force recommendations on the fast track, arguing that the NRC needs more information to proceed.

However, if the NRC balks at implementing new safeguards in a reasonable time frame on the grounds that it doesn’t have enough information about what happened in Japan, then the agency also doesn’t have enough information to relicense operating reactors or license new ones. If the NRC commissioners need more time to sort out the lessons of Fukushima, there should be a moratorium on relicensing old reactors and licensing new ones until they do.

On July 13, we released our own set of recommendations to the NRC, taking a much broader approach.

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NRC Study Shows the Serious Consequences of a Fukushima- Type Accident in the US

, senior scientist

UCS has obtained a preliminary analysis by the Nuclear Regulatory Commission (NRC) of a hypothetical severe accident at a nuclear power plant in Pennsylvania very similar to the one at Fukushima Daiichi. The NRC analysis finds that—even assuming early evacuation of the area—the accident could cause nearly 1,000 cancer deaths among the population within 50 miles of the plant, on average. Under unfavorable weather conditions, that number could be much higher.

The October 2010 draft report, which UCS obtained under the Freedom of Information Act (FOIA), contains some of the results of a long-delayed NRC study known as the State of the Art Reactor Consequence Analyses (SOARCA) project. The NRC initiated SOARCA in 2005 to provide “updated and more realistic analyses of severe reactor accidents.”(Links to the report are given at the end of this post.)

In part, the purpose of SOARCA was to show that such accidents would not be as bad as previous NRC studies had indicated. However, the new study shows that, at least for the 50-mile population, the average predicted risk of cancer deaths is only a factor of 3 lower than if one assumes the worst-case radiation release characteristics used in the 1982 study known as “CRAC2.”  Given the large uncertainties associated with studies of this kind, a difference of a factor of 3 is not significant, so one can conclude that SOARCA essentially confirms, rather than refutes, the results of past studies.

The SOARCA report analyzes the consequences of an earthquake-induced “station blackout”— the total loss of off-site and on-site alternating current (AC) power—at the Peach Bottom nuclear power station in southeast Pennsylvania. This is exactly what happened at the Fukushima nuclear plant. Moreover, Peach Bottom consists of two General Electric Mark I boiling-water reactors. These reactors, known as BWR/4’s, are similar to Fukushima Daiichi units 2, 3, 4 and 5. Thus the event chosen by the NRC to analyze in detail several years ago was uncannily close to the Fukushima Daiichi accident.

The NRC report evaluates two different station blackout (SBO) scenarios. In one of them, known as a long-term SBO, station batteries, which provide direct current (DC) power, continue to operate until they are exhausted, assumed to occur after 4 hours. The batteries cannot power the main coolant systems, but they can provide enough electricity to maintain the instrumentation systems and operate certain valves, allowing operators to manually operate an auxiliary cooling system (known as the Reactor Core Isolation Cooling System, or RCIC) for some period of time.

If additional sources of electrical power are not brought online before the batteries are exhausted, however, operators lose control of the RCIC system, and eventually the system will fail, the reactor core will overheat, the water in the core will boil away, the nuclear fuel in the core will melt, hydrogen gas will accumulate and cause explosions, and radioactive materials will be released into the environment. This is what occurred at Fukushima Daiichi units 2 and 3.

Another scenario SOARCA analyzes is known as a short-term SBO. In this case, DC power is unavailable, operators are not able to use any auxiliary cooling systems, and coolant loss and core melt occur sooner than in the case of the long-term SBO. The event at Fukushima Daiichi unit 1 was essentially a short-term SBO (although because it was a different design than Peach Bottom, the NRC’s analysis is not directly applicable).

The NRC report also evaluated the possibility that operators might be able to use additional mitigative measures to compensate for the loss of all normal sources of AC and DC power. These measures include emergency diesel generators, diesel-driven firewater pumps, and procedures to manually operate the RCIC system and containment venting system without batteries available to power valves and instrumentation. These measures, often called B.5.b measures, were introduced after the 9/11 attacks raised questions about the ability of nuclear plants to recover from the loss of large areas of the plant due to fires and explosions resulting from a malevolent aircraft attack.

However, information revealed by UCS and by the NRC over the last several months has called into question the feasibility and efficacy of these B.5.b measures. So these cannot be assumed to help.

In the long-term SBO analysis with no mitigative measures assumed, the NRC finds that the water level in the reactor core will drop below the top of the nuclear fuel 9 hours after the total loss of power occurs, and the core will be completely uncovered at 11.6 hours. At 19 hours, the nuclear fuel in the core will have completely melted and dropped to the bottom of the reactor vessel, and 30 minutes later the molten fuel will have melted through the reactor vessel and leaked onto the floor of the containment.

The model predicts that hydrogen generated by the reaction of steam with the overheated zirconium alloy encasing the uranium fuel will cause explosions in the reactor building soon after that. These explosions and other phenomena will cause containment failure and significant radiological releases to the environment after 20 hours. (The model predicts that roughly 2% of the cesium and 4% of the iodine in the reactor core is ultimately released to the environment.)

The NRC study assumed that 99.5% of the population within the 10-mile emergency planning zone around Peach Bottom is evacuated within 5 hours and 15 minutes after notification of the accident, and that 50% took potassium iodide tablets. The study also optimistically (and unrealistically) assumed that 20% of the public within 10 to 20 miles away also evacuate within that same time period, even though, as the report admits, “there is no warning or the notification for the public residing in this area, which is not under an evacuation order.”

These two assumptions mean that in the SOARCA study much of the population within 20 miles of the reactor had evacuated long before any radiological releases occurred at the plant. With these assumptions, the study predicts that the average risk to the public within 50 miles of the plant of contracting a fatal cancer is 70 per million. Combining this with the results of a recent report by the Associated Press that found that the population within 50 miles of the Peach Bottom plant is 5.5 million, the NRC predicts that 385 cancer deaths would occur among this population. Much of the radiation exposure causing these illnesses results from long-term occupation of areas that are contaminated but would still be habitable under Pennsylvania laws.

If the people within 20 miles had not finished evacuating in this time, the number of projected  cancer deaths could have been  larger, as some of the evacuating people could have been exposed to the plume.

This can be seen from the analysis of the of the short-term SBO, in which radiological releases are predicted to occur after about 8 hours, and are somewhat higher than for the long-term SBO (2.3% of the cesium inventory and 10% of the iodine inventory). However, due to the rapid evacuation assumed, even in this case the consequences to nearby residents are limited. Still, the study finds the average cancer fatality risk among the 50-mile population in this case is 160 per million; for a population of 5.5 million, this corresponds to 880 cancer deaths, with a greater proportion due to exposure during the early phase of the accident than in the case of the long-term SBO.

The report goes on to note that the result it obtains for the short-term SBO, 160 deaths per million, is only about a factor of 3 smaller than the worst-case result obtained by the using the worst-case radiological release characteristics of the 1982 Sandia CRAC2 study, even though the CRAC2 worst-case was for a much more serious accident that resulted in a much larger radiological release occurring much sooner (and before most of the population in the 10-mile zone was able to evacuate).

Given the very large uncertainties associated with these kinds of analyses, a factor of 3 difference is not meaningful. Also, this is not a true apples-to-apples comparison, because SOARCA did not even do its own analysis of the type of event represented by the worse case in CRAC2, which was a large-break loss of coolant accident with early containment failure. If SOARCA had done such an analysis, it would have found more severe consequences than its analysis for short-term SBO, and the difference between the SOARCA and CRAC2 worst case would have been even smaller.  Thus the SOARCA study, which was intended to show that the CRAC2 results were unrealistically high, has instead essentially confirmed the CRAC2 results.

It’s important to note that the NRC’s results in the SOARCA study are averaged over a large number of different weather conditions. The actual number of cancer deaths resulting from such an accident could be much greater for unfavorable meteorology. The computer codes used by NRC to conduct these analyses typically show that the worst-case results are 10 times the average value, or even larger.

In fact, when the CRAC2 study was first released, it only provided the average values of the results of the health consequences of accidents at U.S. reactors. However, Congressman Ed Markey of Massachusetts obtained and (together with UCS) released a file containing the worst-case results obtained by the Sandia analyses, which did not appear in the NRC report. The fact that the worst-case results were much higher than the average results caused quite a scandal at the time (see, eg, “Nuclear Study Raises Estimates Of Accident Tolls,” Washington Post, Nov. 1, 1982).

For instance, the CRAC2 average number of latent cancer deaths within 500 miles for Peach Bottom was 2,800, but the peak number turned out to be 37,000—thirteen times greater. A similar factor will likely apply to the SOARCA study’s results, so that one might expect as many as 10,000 cancer deaths within 50 miles from the short-term SBO. But just as in the days of CRAC2, the NRC has not provided the maximum values of its analyses.

In summary, the NRC has just spent more than five years and likely a considerable sum of money to essentially reconfirm the validity of the radiological consequence analyses it has been carrying out since the 1980s. This should be a disappointment to nuclear power advocates who were expecting the study to show that the public health consequences of severe accidents were far less than previous studies had indicated. And in fact, the Fukushima accident has provided a real-world demonstration of how large a radioactive release such accidents can cause.

In responding to the UCS FOIA request, the NRC posted the draft SOARCA report on July 14, 2011. It appears in three parts:

SOARCA draft, part 1

SOARCA draft, part 2

SOARCA draft, part 3

The NYT posted a story about this study today.

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Video: What Happened at Fukushima

, co-director and senior scientist

On June 16, Dave Lochbaum spoke at the Boston Public Library as part of an event titled What Happened at Fukushima – Why It Can Happen Here. The event was sponsored by the group C-10.

Also speaking at the event were Arnie Gundersen, an engineer who—like Dave—worked at nuclear plants for many years, and Richard Clapp, Professor Emeritus of Environmental Health at the Boston University School of Public Health.

Click on the image above to see a video of the presentations by Dave and Arnie.

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UCS Recommendations for Nuclear Power Safety and Security After Fukushima

, co-director and senior scientist

Following the disaster at the Fukushima Dai-Ichi nuclear plant in Japan, we began studying what lessons the US should learn from the event and developing a set of recommendations that would increase the safety and security of U.S. nuclear plants.

Today we released US.Nuclear Power After Fukushima: Common-Sense Recommendations for Safety and Security, which details our 23 recommendations for steps the Nuclear Regulatory Commission (NRC) should take. Many of the recommendations address problems that have been evident for decades, while others address problems brought to light during the Japanese crisis.

The top 8 recommendations, discussed in detail on our website are:

  • The NRC should extend the scope of regulations to include the prevention and mitigation of severe accidents.
  • The NRC should modify emergency planning requirements to ensure that everyone at significant risk from a severe accident—not just the people within the arbitrary 10-mile planning zone—is protected.
  • The NRC should require plant owners to move spent fuel at reactor sites from storage pools to dry casks when it has cooled enough to do so.
  • The NRC should enforce its fire protection regulations and compel the owners of more than three dozen reactors to comply with regulations they currently violate.
  • The NRC should establish timeliness goals for resolving safety issues while continuing to meet its timeliness goals for business-related requests from reactor owners.
  • The NRC should revise its assumptions about terrorists’ capabilities to ensure nuclear plants are adequately protected against credible threats, and these assumptions should be reviewed by U.S. intelligence agencies.
  • The NRC should require new reactor designs to be safer than existing reactors.
  • The NRC should increase the value it assigns to a human life in its cost-benefit analyses so the value is consistent with other government agencies.

In the wake of Fukushima, the NRC set up a 90-day task force to review insights from the accident; that task force released its recommendations today. UCS will post an analysis of those recommendations as soon as we have digested them.

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Fukushima Dai-Ichi Unit 3: The First 80 Minutes

, director, Nuclear Safety Project

As described in my first post, I reviewed the detailed data the Tokyo Electric Power Company (TEPCO) released, to understand the operation of Fukushima Units 1, 2, and 3.

The available information for Unit 3 does not extend long after the arrival of the tsunami, and does not extend to the point at which fuel in the reactor core was damaged by overheating. Much of the available information ends at 4:05 pm local time, about 80 minutes after the earthquake occurred at 2:46 pm.

The available information for the first 80 minutes following the earthquake shows:

  1. The reactor shut down around 2:46 pm local time and remained shut down.
  2. Normal power supplies to in-plant equipment were lost about a minute later. It is assumed that this occurred when the operators manually tripped the turbine/generator per procedure.
  3. Both emergency diesel generators on Unit 3 automatically started and connected to their in-plant electrical buses within seconds of the power loss, restoring power to essential plant equipment.
  4. The power interruption caused the main steam isolation valves to automatically close, disconnecting the reactor core from its normal heat sink and disabling the normal source of makeup water to the reactor vessel.
  5. A safety relief valve (SRV) automatically opened around 2:52 pm to control rising pressure inside the reactor vessel. This SRV automatically re-closed when reactor pressure dropped. This SRV followed by two other SRVs cycled opened/closed periodically over the next 73 minutes to control pressure inside the reactor vessel.
  6. The water level inside the reactor vessel steadily declined as cooling water was discharged through the open SRVs into the torus. By 4:00 pm, the water level had dropped below the bottom end of the level monitoring scale. There’s no compelling evidence that any system was used to provide makeup flow to the reactor vessel from the time that the MSIVs closed around 2:48 pm until 4:00 pm.
  7. Around 3:38 pm, one of the emergency diesel generators stopped running. About a minute later, the other emergency diesel generator stopped running. It is assumed that the tsunami caused these failures.
  8. Around 4:02 pm, the RCIC system appears to have been placed in service. The data ends shortly afterwards at 4:05 pm.

Details of my assessment of Unit 3 for the first 80 minutes after the March 11 earthquake are given here.

My assessments of the early behavior of Unit 1 and Unit 2 are available at these links.

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