Spent Fuel Pools Protect The Public. Don’t Believe Skeptics
A two-page Policy Forum opinion piece titled Nuclear safety regulation in the post-Fukushima era: Flawed analyses underlie lax U.S. regulation of spent fuel by Edwin Lyman, Michael Schoeppner and Frank von Hippel appeared in the May 26, 2017 issue of Science Magazine, an outlet that has a public reputation as a reliable source of technical information.
Aside: The UCS has made an arrangement with Science to provide access to a full version of the May 26 opinion piece. The arranged link can be found embedded in the lede of Dr. Lyman’s May 25 All Things Nuclear blog post titled UCS in Science: The NRC Must Act to Reduce the Dangers of Spent Fuel Pool Fires at Nuclear Plants End Aside.
The authors admit in their final paragraph that their goal is instilling concern and distrust. They are seeking to create sufficient public support for their minority viewpoint that the Nuclear Regulatory Commission (NRC) is so closely aligned with the nuclear industry that it protects the industry from spending money on what the authors assert is a grave risk.
“The larger problem of NRC regulatory capture will be dealt with, however, only when pressure from the concerned public outweighs that from the nuclear industry.”
Spent Fuel Pool Fires
The issue that the three authors claim demonstrated the NRC’s condition as a captured regulatory agency is often referred to as a spent fuel pool fire. Specifically, they are worried about the fact that U.S. spent fuel pools are loaded with a large quantity of fuel assemblies that have been used to generate power and thus contain radioactive isotopes, including cesium-137, a gamma emitting isotope with a 30-year half life. They assert that the potential radioactive contamination problem associated with the material in the spent fuel pools could be reduced by moving assemblies that have been out of reactors for more than five years into licensed dry storage containers.
Their premise is that the public will be better protected if the NRC requires nuclear plant operators to reduce the density of their spent fuel pools and limit the amount of material that could potentially be released.
The NRC has invested many thousands of professional staff hours and and uncounted number of millions of dollars addressing the concerns raised by Lyman, von Hippel, Schoeppner and other critics in an effort that has lasted at least 30 years. Via SECY-16-0100, dated August 24, 2016, Victor McCree, the current Executive Director for Operations at the NRC, reaffirmed the staff’s position on spent fuel pools to the Commission and the public.
That short Policy Issue Information paper has a 22-page enclosure that addresses each of the findings of the National Academy of Sciences work mentioned in the Lyman, von Hippel, and Schoeppner Science Policy Forum opinion piece in excruciating detail.
The following conclusion statement from SECY-16-0100 should set most minds at ease, even if it does not satisfy or quiet the stubborn critics.
The staff concludes that spent fuel continues to be stored safely and securely at nuclear power plants in both spent fuel pools and dry casks. The security of U.S. nuclear power plants remains extremely robust.
The enclosed NRC assessment of the current NAS study reflects an extensive history of how spent fuel safety and security have been assessed and improved in the United States. Significant enhancements to the safety and security of nuclear power plants, including spent fuel pools, were made following the terrorist events of September 11, 2001, and the Fukushima accident in 2011.
Spent fuel pool safety was enhanced at U.S. reactors when licensees implemented new NRC requirements to develop strategies for spent fuel pool cooling following losses of large areas of the plant due to fires, explosions, or extreme natural events. The NRC will continue to cooperate with other federal agencies and international organizations to assess possible threats to nuclear power plants and to improve risk assessment techniques. The staff will continue to bring policy matters to the Commission for consideration and action as appropriate.
(Reference: SECY-16-0100 p. 4. Emphasis and paragraph breaks added.)
Why Does This Issue Periodically Capture Public Attention?
Worries about the radiological consequences of a fire in a spent fuel pool might seem otherworldly to those of us who have seen spent fuel pools and understand that they are 40 feet deep pools of water with very thick concrete walls lined with a thick, penetration-free steel liner. Fires and pools are not two words that go together very well. Until 2001, one could confidently assert that the vast majority of the general public would yawn if told they should worry about a fire in a pool, no matter what kind of pool it was.
In the aftermath of 9-11, Americans were open to hearing about new reasons to be concerned, so people opposed to nuclear energy seized the opportunity provided by the crisis to raise the issue of spent fuel pool fires postulated to be the result of a hypothetical terrorist attack that caused widespread damage at a nuclear plant.
Once again, a crisis presented an opportunity to nuclear opponents. During the Fukushima Frenzy, Dr. Greg Jaczko, then serving as Chairman of the NRC, raised the issue of spent fuel pool fires to a whole new level of public awareness. It is a topic that had been simmering inside the nuclear enterprise for several decades. Most of the people who were aware of the issue had determined that it was highly unlikely and carried relatively low probability of harm even if the rare conditions required somehow were assumed to occur in the proper sequence.
On March 17, 2011, Dr. Jaczko told Congress in a public hearing that the March 11 earthquake and tsunami had successfully created the necessary conditions in the spent fuel pool at Fukushima Unit 4. According to his testimony, the unit 4 spent fuel pool was dry and burning, releasing enough material to support his recommendation to evacuate all U.S. personnel within 50 miles of the Fukushima Dai-ichi nuclear power station.
The Internet is full of articles and commentary that stimulate discussion about spent fuel pool fires; many of them point to Fukushima Unit 4 as either a catastrophe that happened [accuracy is not necessarily the strong suite of historical internet documents or news reports] or a near miss that could have happened.
As a result of the concerns stoked by Jaczko’s testimony, the NRC received strong encouragement from several NGOs and from congressional oversight committees to address the issue. That pressure continued even after the Frenzy had calmed down enough for more sober investigators to determine (p.2) that the spent fuel pool for unit 4 had never come close to being emptied and that the fuel temperature had most likely not exceeded 100 ℃.
“On March 11, 2011, a 9.0-magnitude earthquake struck Japan and was followed by a 45-foot tsunami, which resulted in extensive damage to the nuclear power reactors at the Fukushima Dai-ichi facility. After the onset of core damage in some units, there were significant concerns about the integrity of SFPs and the possible release of radioactive materials from the spent fuel assemblies. However, subsequent inspections determined that pool integrity had been maintained, the integrity of the spent fuel cladding had not been challenged, and equipment to restore coolant inventory had been successfully deployed, despite radiological hazards and extensive damage to the surrounding structures from the tsunami and hydrogen explosions. While the SFPs and the spent fuel assemblies at the site remained intact, the event led to questions about the safe storage of spent fuel and whether the NRC should require expedited transfer of spent fuel to dry cask storage at nuclear power plants.”
The Science Policy Forum piece is part of a sustained effort by the team of Lyman, von Hippel and Schoeppner to create public fear and distrust strong enough to stimulate political action. In the May 24, 2016 issue of Science, Richard Stone published a brief report in Science titled Spent fuel fire on U.S. soil could dwarf impact of Fukushima. That report quoted Lyman and von Hippel and described the dispersal simulation created by Schoeppner in support of a paper that the three were planning to submit to the journal Science & Global Security.
That proposed paper was submitted and accepted. It appeared online on May 8, 2017, less than three weeks before the opinion piece in Science was published.
The three assumed that the NRC had correctly computed the maximum amount of cesium-137 that could be released if there was some kind of initiating event that partially drained a spent fuel pool and prevented any successful efforts by plant operators or first responders. In this “nightmare scenario,” the resulting lack of cooling, combined with the continuing addition of decay heat from fuel assemblies force material temperatures high enough to cause protective cladding to fully react with either air, steam or a combination of the two.
The scenario assumes that the reaction is rapid enough to cause an explosive accumulation of hydrogen gas that ignites and eliminates the retention effect of the building that houses the fuel pool. The reaction is also rapid enough to generate the kind of updraft that will loft material from the pool to a sufficient height that it can be dispersed by winds over distances in excess of 50 miles – 80 km.
Using a source term of 1600 petabecquerels of Cs-137 – 100 times as much as was released by melting three reactor cores at Fukushima – the trio ran simulations in which the release was from the Peach Bottom nuclear station. They computed the contamination levels resulting if the release happened on the first day of each month using weather information from 2015 and created maps of average land concentration. They assumed that all areas in which the land contamination value exceeded 1.5 MBq/m2 would be evacuated.
Based on the government actions following Chernobyl and Fukushima, they expect that the evacuations would turn into long-term relocations with devastating political, economic and mental health consequences.
Their simulations, using the same maximum release value as used by the NRC in its evaluation of the situation, produced an evacuation land area that was three times larger and included five times as many people as the NRC’s worst described case. Based on their consequence results, they believe that the NRC wrongfully chose not to force nuclear plant operators to perform a more rapid transfer of spent fuel out of pools and into dry storage containers. They assert that the NRC’s decision was that of a captured agency responding to industry pressure at the expense of public safety.
Their thesis is that the Commission chose inaction in order to protect the industry from the $5 billion cost of the expedited transfer program and not because the agency determined that the public is more than adequately protected under current conditions.
Regulators Agree There’s No Reason To Worry
The NRC staff’s recommendation to the Commission following its study of the risk and potential consequences of a spent fuel pool fire and the potential benefit of requiring an expedited program of moving fuel from spent fuel pools into dry storage containers is documented in COMSECY-13-0030 dated as follows:
The staff’s assessment concludes that the expedited transfer of spent fuel to dry cask storage would provide only a minor or limited safety benefit, and that its expected implementation costs would not be warranted. Therefore, the staff recommends that no further generic assessments3 be pursued related to possible regulatory actions to require the expedited transfer of spent fuel to dry cask storage and that this Tier 3 Japan lessons-learned activity be closed.
The staff did not reach that recommendation quickly or cheaply. The conclusion is provided as part of a ten page memorandum that enclosed a 159 page supporting document titled Regulatory Analysis for Japan Lessons-Learned Tier 3 Issue on Expedited Transfer of Spent Fuel
That regulatory analysis was based on previously completed work, including a congressionally mandated post-Fukushima effort that was documented in a 416 page study titled Consequence Study of a Beyond-Design-Basis Earthquake Affecting the Spent Fuel Pool for a U.S. Mark I Boiling Water Reactor dated October 2013. I haven’t asked what the entire effort cost, but the Consequences study itself was the result of more than $3 million and 11,000 professional staff hours spent during FY11-FY13.
When asked for a comment in response to the publication of the Science opinion piece questioning the NRC’s competence and integrity as an effective safety regulator, Scott Burnell of the NRC’s public affairs office provided the following statement.
“The staff’s analysis followed well-established, Commission-approved directives for identifying all attributes affected by the proposed alternative and analyzing them either quantitatively or qualitatively (https://www.nrc.gov/reading-rm/doc-collections/commission/secys/2013/2013-0112scy.pdf). The staff’s technical conclusions regarding potential safety benefits were reached before considering potential costs.
The NRC’s current conclusions regarding spent fuel pool safety and security are best summarized by the staff’s response last summer to the National Academies Phase 2 report on lessons learned from Fukushima:
The NRC welcomes well-supported analysis on issues relating to the agency’s mission. The staff will review the Science policy paper and determine whether any additional action is required. Absent such a review, the NRC stands by the conclusions from the staff’s work to date.”
Skeptics Stubbornly Assert They’re Correct
When contacted via email, von Hippel and Lyman stood by their assertions that the NRC had not properly considered the societal cost of a wide-spread relocation effort and the loss of effective economic use of large swaths of heavily populated areas. They asserted that the NRC chose to ignore the possibility of terrorist action while they asserted that terrorists were fully capable of causing the required damage to spent fuel pools while also maintaining enough control of the area to prevent operators from taking any planned or improvised mitigating actions.
“Adams: Can you explain why you and your coauthors think that the public should be so concerned about such improbable event with such a tiny health risk that they should be willing to spend $5 billion to modestly reduce the potential?
von Hippel: I can only speak for myself. I think that the risk that the NRC estimated of 0.14 to 6 percent during the next 20 years of an event that would on average require the long-term relocation of 8 million (our estimate; the NRC estimated 1.3-8.7 million) is significant. On top of that, I would add the terrorist risk. On top of that, I would add that, when we correct the NRC’s cost-benefit analysis, the average probability-weighted benefits would exceed the costs even before taking into account the risk of terrorism.”
When I pressed harder regarding the inability of terrorists to impose the kind of widespread infrastructure obstacles that can be imposed by earthquakes, tsunami or major storms and suggested that the U.S. might be able to avoid the kind of relocations imposed in Ukraine or Japan, Dr. Lyman weighed in with the following additional comments.
“We aren’t alleging that terrorism would necessarily result in worse consequences than accidents. But a deliberate attack can be engineered to induce consequences similar to the most severe, low-probability accidents, yet the NRC’s quantitative risk methodology does not take that into account. What we are proposing is a defense-in-depth measure to reduce the consequences should such an attack occur. And I disagree with you that a terrorist attack would necessarily be of more limited scope than a natural disaster. Terrorists can both interfere with on-site emergency response and deny site access to external responders — tactics that are seen routinely around the world.
And on your last point, our article should make clear that we agree that the societal disruption due to long-term relocation is a significant consequence that is not accounted for in the NRC’s methodology. But it is unrealistic to expect that spontaneous relocation would not take place from contaminated areas even if the government tried to assure people that it was safe to stay. The best way to avoid such impacts is to reduce the risk of such an event in the first place.”
In a second installment, I will address additional considerations and correspondence. But the bottom line here is that the responsible professionals at the Nuclear Regulatory Commission have determined that the public has nothing to worry about regarding the current conditions of spent fuel pools. In contrast, a small group of physicists disagree and want the public to support their quest for expensive political action.
Both before and after writing the above, I engaged in a spirited email exchange with Drs. Frank von Hippel (Princeton University) and Edwin Lyman (Union of Concerned Scientists). Their point of view is fundamentally different from mine and is based on the vast differences in our educational and professional backgrounds. In my view, it is worthwhile to engage in a discussion in public to allow observers a better opportunity to make informed choices on important issues.
Dr. von Hippel provided the following rebuttal to the above post. I will address this response along with additional thoughts about the vast differences in perception between us regarding hazards related to the radioactive material stored in spent fuel pools under current regulations.
On how close the spent fuel in Fukushima pool #4 came to be uncovered, I would reference the discussion in chapter 2 of the National Academy of Sciences report. See especially the discussion associated with Figure 2.15.
With regard to the representation of our work, Rod links only to the article summary because the article itself is behind a paywall. UCS has, however, provided a link to the full article. Ed Lyman can provide that link.
Rod demeans our analysis as only two pages while ignoring the two backup articles in Science & Global Security referenced there, of which he is aware, and for which I have provided links.
Reducing the Danger from Fires in Spent Fuel Pools, Science & Global Security Vol. 24, No. 3, 141–173
Economic Losses From a Fire in a Dense-Packed U.S. Spent Fuel Pool Science & Global Security Volume 25, 2017 – Issue 2 May 2017.
Rod demeans us three as fringe characters while representing the NRC as a font of unbiased wisdom. Although it doesn’t seem to bother Rod, most people find it pretty devastating to the NRC’s credibility when they learn of the omissions and mistakes that we have pointed in the staff’s analysis: ignoring the possibility of terrorism, leaving out consequences beyond 50 miles, and in its computer program secretly increasing the contamination threshold for relocation three-fold and assuming that decontamination by up to a factor of 15 of an area the size of New Jersey can be accomplished within a year.
I would also note that, in his effort to represent us as fringe characters, Rod has ignored that our work builds on the four-year-long National Academy of Sciences study referenced above which includes many of the criticisms that he attributes to us, including the NRC’s refusal to consider the possibility of terrorism and or take into account consequences beyond 50 miles. Indeed, the NRC, in a “sensitivity study” quoted in the NAS report, concluded that including the consequences beyond 50 miles and updating its value for a human life lost to cancer would have increased fivefold the consequences it used in its cost-benefit analysis. That would have brought its cost-benefit analysis to the break-even point without including the possibility of terrorism. The additional errors that we pointed out with respect to relocation threshold and decontamination timescale increased the accident consequences by another factor of three.
Rod’s piece does not even hint at the above. Based on my exchanges with him, his answer that we are wrong and the NRC is right is unchangeable but the arguments on which he bases that conclusion changed completely with each cycle of our exchange. That is why I decided to give up trying to educate him.
You can use the above as a rebuttal. I would request also that you flag our backup articles and add the above links.
Frank N. von Hippel, Senior Research Physicist and
Professor of Public and International Affairs emeritus
Program on Science and Global Security and
International Panel on Fissile Materials
Note: A version of the above was first published on Forbes.com. It has been modified with additional information about the current position of the NRC staff as documented in SECY-16-0100. It is republished here with permission.
I am under the impression that each nuclear power plant has a large security staff.
You would be very correct in that impression, including the Local Law Enforcement and FBI involvement. This whole thing just sounds like the post 911 scare tactics about aircraft impacts all over again. Folks, it’s been demonstrated and proven, there’s not much to see here other than people digging in their heels on what they feel is a big issue. I can tell you first hand, the NRC is not interested in being friends with the power producers. We are cordial and all business, everyday, but no one is out having drinks together after work. Can’t say the same for oil and gas though….shouldn’t we be watching them like we get watched? After all, a couple of $9 per hour folks with flashlights and a phone at the front gate protecting a massive potential fireball that could wipe out an area very easily seems more scary than our SFPs…
Rod, has anyone ever done a back of the envelope guesstimate on the price of oil and gas if they even had to upgrade their physical security and cyber security like we do? Something tells me the price of gas as a potential replacement for nuke wouldn’t even be in the ball park, based upon the risks (target sets, locations, etc.).
Should we include cost of the US military forces deployed in the middle east?
I heard that the US navy spends ~$60 billion per year just patrolling the Persian Gulf.
All that to provide “security of supply” to all the nations dependent on oil/gas imports. (South Korea now volunteering to become far more dependent.) Of note is that we still spend all that despite the oil and gas “miracle” happening in our country, and that our level of foreign dependence is much smaller, almost non-existent.
One justification may be that, since oil and gas are fungible, international commodities, a supply disruption would still impact the US economy, as the world price (including those at home) would go way up, even if we were not a net importer. (The US oil/gas producers would make a mint, however….)
I have to wonder if the US actually likes this situation; more than they would like to see all nations become energy independent. Have the world be utterly dependent on the delivery of a commodity from an unstable part of the world, and have the US (imperial) navy be essentially be in control of those supplies. Would kinda put the US in a position of advantage in any negotiations or dealings with other countries, don’t you think? Subtle blackmail?
I also have to wonder if the oil/gas industry bankrolled the campaign of South Korea’s new president. Or if they’ve been wielding their influence in places like Taiwan as well. In addition to nuclear’s suffering at home due to (created?) economic problems, nations all over the world are making direct political decisions to close down nuclear (even if it is less expensive) and replacing it with gas. I smell powerful influence.
They do. A sizable and armed staff.
From the EL Blog:
“The danger could be greatly reduced if plant owners thinned out the pools by transferring their older fuel to dry storage casks. But despite the relatively modest cost of this common-sense step—about $50 million per reactor—owners won’t do it voluntarily because they care more about their bottom line.”
Only an academic or someone similarly out of touch could call $50 million “relatively modest.” Just what does EL think the plant cash flow is? Let alone the operating profit available for such projects?
This is simply another scare-mongering pretext for pricing nuclear out of business.
By the way, the full Science article appears to be behind the paywall. At least I cant get to it.
Did you follow the link to the All Things Nuclear blog and then try to click the link posted there?
Yes I did; it sent me to the Science page that requires login. But, when I tried again (on my phone, instead of my employers laptop), it sent me right to the article. Weird. Anyway, thanks for the link.
I thought that the NAS study showed that the very idea of a SFP cladding fire was rather dubious, and that it was only (remotely) possible at a handful of sites (pools). They went on to say that they would need to do further (more detailed) analysis to confirm that it was even possible, at that handful of pools. But their initial, conservative review/analysis was enough to show that it wasn’t even possible at the great majority of pools.
Is my understanding incorrect?
BTW, I actually agree with them that an up to 6% chance is indeed very significant. So significant, that I find it almost impossible to believe. I’m surprised that NRC came up with such a high number. But then I remind myself how unrealistically conservative nuclear analyses are (having done many such analyses myself). The notion of an SFP fire having a 6% likelihood being one more wonderful product of such flawed, unrealistically conservative analysis. A 6% chance that, in ~2 weeks (?), they wouldn’t be able to arrange to bring a hose near the pool and spray some water on it? Seriously??
We have multiple, massive Godwin pumps (diesel) that can pump water into the SFP using multiple sources of water……like our spray ponds (ultimate heat sink) We can also use fire protection water via our fire protection pumps.
That is a good point.
The SFP rapid draining issue really only exists with BWR plants, with SFPs installed high above grade.
Moreover, the fire issue only arises with COMPLETE drainage, such as is only made possible by a hole in the bottom of the SFP.
With partial drainage, the hot air circulation required for fire initiation — as demonstrated by Sandia experiments — does not exist.
Of course in-ground SFPs at PWRs don’t have this issue at all.
The risk of drainage may be higher with BWR sfps, however due to lower power density, BWR fuel is far less likely to ignite.
Also the bwrs I’ve been at have remotely operated fire protection and emergency service water valves to fill the pools in an emergency.
The scenario that supposedly causes the kind of large scale release that von Hippel & Lyman want us all to worry about is a rapid pool drain that stops just in time so that the water and debris remaining at the bottom of the pool stops all air from flowing past the exposed part of the fuel assemblies. They model the effects of this situation as an adiabatic heat up of the fuel assemblies.
The blockage that prevents any kind of cooling magically disappears when oxidation begins to ensure there is plenty of wet air flow to sustain an oxidation reaction that rapidly releases enough H2 to accumulate and explode to both remove all of the structures above the pool and loft the radioactive material in the pool to an elevation high enough so that the wind can carry it to distant locales that are 80 or more kilometers from the pool.
That material is deposited in such a manner as to contaminate thousands of square km of surfaces to a level exceeding 1.5 MBq/m^2. At that contamination level in an unshielded scenario, people will be exposed to doses exceeding the relocation recommendations of the U. S. Environmental Protection Agency and used at Chernobyl and Fukushima. (20 mSv in first year and/or 5 mSv/yr for the subsequent four years for an assumed total of 40 mSv.)
IMO all of those cascading conservatisms don’t result in a conservative estimate of hazard; they produce an estimate that is wildly exaggerated and inaccurate.
My reading of Von Hippel & Lyman’s Policy Forum article is that the chief concern is an SFP fire.
They state that “Dense-packed spent fuel would be susceptible to catching fire if an accident or terrorist attack caused a loss of the pool’s cooling water.”
“NRC contractors at Sandia National Laboratory estimated that, had there been a fire in pool 4, 100 times as much cesium-137 would have been released to the atmosphere than actually
leaked from the damaged Fukushima reactors.”
“After Fukushima, the NRC evaluated whether to require nuclear power plants to reduce the risk of a catastrophic spent fuel fire….”
Indeed, SFP fire is the only mechanism for a large release of radioisotopes.
The hydrogen explosion may be very dramatic, but by itself it does not lead to much radioisotope release from the SFP (and is readily avoided with PARs – Passive Autocatalytic hydrogen Recombiners – which all Japanese plants now have).
The Sandia series of experiments clearly demonstrated a couple of things: A zirconium fire in LWR fuel is very difficult to achieve, requiring temperatures of about 1,000ºC, PLUS circulation of heated air at several hundred degrees, from below the fuel assembly support grid, up through the channel box, and out the top.
Blockage of hot air circulation starves the zirconium fire.
Indeed, the test runs showed that after ignition, there is rapid oscillation in fire intensity inside each fuel channel box, as oxygen is alternately consumed and replenished by the air flow from below.
Results from the Sandia experiments were used to calibrate NRC’s MELCOR code, which can then be used to simulate a large-scale fire in the entire SFP – as well as the resulting radioisotope releases.
There is no doubt that the calibrated MELCOR code makes valid predictions for postulated circumstances.
The significance of uncovering the top of fuel in an SFP is simply that dose rates on the refuelling floor around the pool become far too high for mitigating action – the stated assumption being that once that happens, a complete dry-out of the SFP is inevitable, either by continued draining, by water boil-off, or by a combination of the two.
As long as there is water in the SFP, even well below the level of top of fuel assemblies, the continued cooling by water boiling off, at ambient pressure, cools the zirconium to well below 1,000ºC, while at the same time blocking hot air flow into the channel boxes from below.
In other words, no fire until complete dry-out.
Now, if as “Bonds 25” says, there are means of continued refilling of the SFP remotely, even in a large hole / rapid drainage scenario, then the fire risk goes away completely.
And, as we saw at both Fukushima and Onagawa, not even the massive Tohoku earthquake was able to crack & drain ANY of the SFPs.
My point exactly. So why is NRC talking about an up to 6% chance? What is that based on?
I have a sense that they may have done probability studies for a handful of parameters, while ignoring the presence of extremely (unrealistically) conservative assumptions for a host of other parameters that affect the calculations (such as the examples Rod gave).
If that is the case, then quoting a percent chance based on statistical analysis of only some parameters is a disservice. It’s one thing to qualitatively state that something is “possible” or “worst-case”, but if you’re going to quote a percent chance, then it better be at least remotely accurate. That is, it must consider the probabilities associated with all parameter inputs or other assumptions.
Adiabatic heating is obviously an absurdly unrealistic assumption. I don’t understand how blockage of the bottom would prevent all air (convective) cooling. At least some air would be able to enter from the sides. It would be hard for air to get in with channeled assemblies, but it still would not be zero.
And my understanding is that even a small amount of air flow makes a significant difference, relative to a literally adiabatic configuration. Nature abhors extremely high temperatures (as it abhors a vacuum). It is very difficult to create conditions where such high temperatures can occur.
The assumption that losing shielding from water halts all mitigation might have been valid before we learned a valuable response technique during the Fukushima Frenzy.
As my good friend Cal Abel realized and managed to share with responders in Japan, if you want to pump water with precision into a tank that you cannot approach, there is a readily available answer – use the type of articulated boom pump truck that is used on construction sites.
Though those trucks are designed to precisely place concrete, they move water with even greater ease. Though often associated with high rise construction in cities, I see them frequently in my relatively new and still under construction neighborhood when basements or foundation slabs are being poured.
The concrete mixer sits on the street and the articulated boom allows the concrete to be placed several hundred feet away from the source. Concrete mixer trucks can carry a lot of water instead of concrete.
The fact that emptying a pool down to the top of fuel assemblies causes a substantial spike in gamma radiation also provided the responders at Fukushima with a valuable indication that there was still water remaining in the pool. Since they did not get the spike, they logically put a fairly low priority on adding water to the pool.
The idiotic panic by NRC representatives on the ground about the unit 4 SFP lead to their ridiculous – or carefully crafted – recommendation to try dropping water from helicopters into the pool. That was mathematically ignorant, but it led to a great video shot that could be used as a call-back to Chernobyl for the antinuclear movement where Jaczko had learned everything he knew about nuclear energy before his appointment as a Commissioner.
Here’s an excerpt from a post I published on March 17, 2011:
We also have a fire truck onsite with a spray monitor that can reach the top of our Reactor Building (which is the tallest in the USA) This was a post 9-11 B.5.b regulation issued by the NRC.
The fire trucks did ok at Fukushima, but the articulated boom trucks did a better job of precisely placing water into the pool. Though water isn’t expensive, it’s available in limited quantities during a casualty response effort due to the need to move it from place to place.
I’m only speculating here, but I believe directing water into pools instead of spraying it in the direction of pools provides several additional benefits to the responders.
Oil, gas, hydro, wind and solar should be held to the same potential, predicted and possible death rate as nuclear power. Lost Time accidents at Tesla is an order of magnitude worse than the worse NPP.
“Oil, gas, hydro, wind and solar should be held to the same potential, predicted and possible death rate as nuclear power.”
Do these industries also have Academics scrutinizing their processes to a similar extent? Somehow, I get the idea that the somewhat exotic nature of nuclear power draws these guys to do analyses like a moth to a flame. A similar analysis to a chemical storage facility could possibly be quickly dismissed. It is a shame that there are so many causing excessive “corrective” spending in an energy source that could eliminate the problem of global warming.
I hope you realize that the National Academy of Sciences does not choose the subjects that it studies. An NAS study is a very expensive effort; they have a lot of fancy infrastructure to maintain and some generous salaries and consulting fees to pay.
The NAS study mentioned here was demanded by Congress, which told the NRC to fund it out of its operating budget. Though I have not taken the time to trace where the pressure came from, my guess is that it involved Boxer, Markey and Sanders, among other nuclear energy critics/fear mongers.
“I hope you realize that the National Academy of Sciences does not choose the subjects that it studies”
Well – I guess I do now.
“my guess is that it involved Boxer, Markey and Sanders, among other nuclear energy critics/fear mongers.”
Of the three, I think there is still hope for Bernie Sanders. His wife just started the Sanders Institute. Among the movie stars and their cronies making up this organization is Jeffrey Sachs. Surprisingly, enough, he is not anti-nuke.
Maybe, he’ll have some influence on old Bernie.
It does certainly seem there are items that warrant study with a more immediate need than nuclear fuel pools.
Rod, thank you for this careful research.
The opponents are happy to attack anything. At Vermont Yankee, a major anti-nuclear activist is attacking plans to transfer the fuel from the pools to dry casks. He claims to worry about the children in the school across the street. He says VY should wait till school is out of session to move the fuel.
Opponents are not really concerned about fuel fires IMHO. It’s just another point of attack.
The discussion about Gorleben started with this 2011 publication in Environ Sci Pollut Res Int, about a.o. the 0.4% on av. increased m/f sex odds in Europe (39 countries) after Chernobyl.
It provoked discussion. Pubmed gives an overview.
This presentation delivers easy to read background and an overview regarding the increased genetic damage around Gorleben, etc.
Ordered by the state (Niedersachsen), pro-nuclear scientists extended the original study area mainly to the east and found to the their unpleasant surprise even worse genetic damage. Not strange as local winds are from the west, but they were convinced Scherb etal found artifacts. Though they couldn’t find a non Gorleben explanation for their results, they still tried to deny.
The state then organized a conference at which all involved scientists presented and discussed (all PPT’s can be downloaded from the conference page).
At the end the original study authors got the assignment to write the final report for federal govt (Berlin). After about ~half a year Berlin decided to close the still 70% empty facility.
I notice that all the references cited are authored by Hagen Scherb and Kristina Voigt.
Sherb is a co-signer of the so-called “Lesvos Declaration”, along with Chris Busby, Inge Schmitz-Feuerhake, Alexey Yablokov, Sebastian Pflugbeil, and other discredited “researchers” who engage in generating bogus statistical results.
This is NOT the “Reliable scientific citation” that was requested by “turnages says” above.
European Committee on Radiation
The Lesvos Declaration, 6th May 2009
Professor Yuri Bandazhevski (Belarus),
Professor Carmel Mothershill (Canada),
Dr Christos Matsoukas (Greece),
Professor Chris Busby (UK),
Professor Roza Goncharova (Belarus),
Professor Alexey Yablokov (Russia),
Professor Mikhail Malko (Belarus),
Professor Shoji Sawada (Japan),
Professor Daniil Gluzman
(Ukraine), Professor Angelina Nyagu (Ukraine),
Dr Hagen Scherb (Germany),
Professor Alexey Nesterenko (Belarus),
Professor Inge Schmitz-Feuerhake
(Germany), Dr Sebastian Pflugbeil (Germany),
Professor Michel Fernex (France),
Dr Alfred Koerblein (Germany)
Check the links in my comments and the links in the presentation I linked. It concerns many publications in peer reviewed scientific journals.
Check also the more sophisticated attacks and the responses in the Pubmed overview which I linked above.
As well those in the PPT’s by the pro-nuclear presenters at the conference which I linked above.
All those attacks cannot convince as those cannot explain the sudden ~10% increase of the m/t sex ratio of newborn up to 40km away at Gorleben. Neither similar (though lower) sudden increases around NPP’s the moment those start to operate.
It’s clear that the attacks couldn’t convince German authorities at the conference, as Scherb etal got the assignment to write the concluding document for federal govt after the conference.
Actually your cited “verlorene maedchen” PDF disputes that…
“Grundsatzlich bleibt es zu betonen, dass nur wenige effekte als einflussfaktoren des geschlechtsverhaltnisses etabliert sind; Selbst risiken, die die reproduktivitait betreffen, wie zigarettenverbrauch oder eben auch ionisierende strahlung, scheinen keinen impact auf das geschlechterverhaltnis der nachkommen zu habben.”
“In principle, it has to be emphasized that only a few effects are established as influencing factors of gender relations; Even risks affecting reproducibility, such as cigarette consumption or even ionizing radiation, do not seem to have any impact on the gender balance of the offspring.”
I’m completely unconvinced that Dry Cask Storage (in which nuclear material is basically inert could have had as big of an impact as is claimed here.)
But that’s just your interpretation of the entire thing. You haven’t shown any evidence that the Dry Cask Storage has anything to do with a so-called gender unbalance, as far as it has been recorded.
Remember – Correlation doesn’t mean Causation. And to suppose that “just because scientists can’t find it, means they are wrong” is far too simplistic and naive for my taste. It smells of conspiratorial thinking, which almost always ends up in Disqualification.
Can you show me how much radiation escapes from this facility in the first place?
Remember, these things are sealed…
“Dry cask storage allows spent fuel that has already been cooled in the spent fuel pool for at least one year to be surrounded by inert gas inside a container called a cask. The casks are typically steel cylinders that are either welded or bolted closed. The steel cylinder provides a leak-tight confinement of the spent fuel. Each cylinder is surrounded by additional steel, concrete, or other material to provide radiation shielding to workers and members of the public. Some of the cask designs can be used for both storage and transportation.”
Then explain this, there are 16 dry cask storage facilities in use in Germany, with more than one thousand Dry Casks. Can you quantify the amount of radiation leaking from these casks, and how much argon is produced.
And how does this stack up against natural sources of radiation? Aside from that, you do know that Argon40 is a decay product of naturally occurring Potassium40, right?
NRC only states those provide radiation shielding for the public.
And yes, chance is extremely small that someone passing the dry casks will get cancer.
But note that the NRC does not state that the freed neutrons (or other particles) will all be absorbed by the steel (steel is a bad absorber) or the concrete (which is better as it contains in general a lot of water)…
So those neutrons may affect via the argon mechanisms, genetic health of children which are conceived that night or the ~4 nights thereafter.
The casks used in Germany are thick walled standard casks. Same are also used in USA. Though in USA also thin walled standard casks are used.
The German casks are also suited for and used for transportation.
“Spent” bundles are cooled using natural air circulation in the concrete cask which cools the helium inside the metal liner. Neutron dose rates on the casks (ONLY on contact with the vents) are <1 to 1 mrem/hr. The high majority of our (36) casks are <1 mrem/hr Neutron.
Gamma dose rates…again ONLY on contact with the vents are <1 to 2 mrem/hr.
I know this because I actually PERFORM these surveys. So, you're telling me these are dangerous levels? Hahaha
Gresnigt talks about radioactive Argon-41 production by neutrons escaping from SNF casks.
How significant can that be ?
How does it compare to natural ambient Ar41 production?
The incident cosmic ray neutron flux is approximately 1 neutron per second per square centimeter of the earth’s surface.
So, each square kilometer of the earth gets about 10 billion neutrons per second ( = 10E9 n/sec).
By comparison, the total neutron production inside an SNF cask is about 0.6E9 n/sec.
However, only a tiny fraction of that total gets outside the cask, or even outside the fuel rods themselves: Many fission products in the fuel absorb neutrons.
For example, Nd147, Pm147, Sm149, Sm151, Sm152, absorb neutrons at a rate from about 1,000 to 10,000 greater than Argon (for comparison).
Other components of the fuel – mainly Uranium – also absorb neutrons, as of course does the thick cask wall.
If 0.1% of neutrons produced inside the cask make it out, that comes to 0.0006E9 n/sec.
Suppose a storage site has 100 dry storage casks. That then comes to 0.06E9 n/sec total from the site.
By comparison, if the storage site is at the center of four squares, each 1 km^2, then the ambient natural background is 40E9 n/sec – 670 times the rate from the 100 stored fuel casks.
Consequently, the rate of natural radioactive Ar41 production will also be about 670 times the amount of Ar41 coming from the SNF storage site.
Gresnigt & co. need to explain how Ar41 from SNF storage is of any significance, relative to natural Ar41 production – let alone any kind of factor in population sex ratio.
Gorleben was the prime nuclear power waste dry storage location in Germany.
I assume that there are more such locations as hospitals, etc. also generate such waste. Furthermore that the new nuclear power dry casks are distributed around at other storage locations now.
I’m not aware of measurements around those.
“… bundles are cooled using natural air circulation in the concrete cask…”
If true, than part of the argon nucleus in that cooling air will become radio-active (AR-41) due to collision with neutrons.
Which sets the stage for similar increased m/f sex ratio of new born up to 40km away (if there is “normal” local wind) as found around Gorleben.
E.g. male nuclear workers at Sellafield get 39% more boys than girls, while there is no doubt that safety standards are followed. Which implies increased genetic damage. Hence research found significant increased risks on stillbirth (Parker etal) and cancers for that offspring.
Thanks for your theory.
Near all neutrons coming from space collide high in the air (stratosphere). So that formed Ar-41 won’t reach the surface.
Theory is nice but repeated statistical measurements involving all newborn (so no sampling errors), show again and again the significant increased m/f sex ratio of newborn up to 40km away from significant nuclear facilities.
In one response to Adams:
“von Hippel: I can only speak for myself. I think that the risk that the NRC estimated of 0.14 to 6 percent during the next 20 years of an event that would on average require the long-term relocation of 8 million (our estimate; the NRC estimated 1.3-8.7 million) is significant. ”
Risk estimates aside — which as Rod points out, “produce an estimate that is wildly exaggerated and inaccurate.” — there needs to be more attention turned to the need for short-term emergency evacuation as well as long-term expulsion based on needlessly low radiation thresholds in place based on ALARA principles. Surely Fukushima has demonstrated how official panic led to deaths whereas radiation caused exactly zero deaths. Japan, more specifically the Fukushima prefect, is still recovering from needless expulsion.
This graph composed by Wade Allison illustrates how ridiculously low current thesholds have been set by government agencies. As is well known, ALARA regulations are based on the failed LNT hypothesis. Godspeed to the efforts undertaken by the volunteer medical physicists and biologists at SIRI and XLNT attempting to convince the NRC and EPA that current standards are insanely low and serve only to promote radiophobic FUD and ensuing panic in the event of a nuclear accident, however insignificant it might be.
1st Argon40 is a naturally occurring isotope which is a decay product of the naturally abundant Potassium40.
2nd there are 16 other Dry Cask Facilities in Germany with over one Thousand dry casks. Why does this happen in only one place? Can you explain the anomaly? How does this anomaly stack up against multiple dozens of these facilities?
Oh sure thanks Mathijs! You must be causing Bas much concern. Just a wild guess that Bas didn’t know about the other sites. With this new information, he must be getting a special tingly feeling in his nether regions. Hopefully when he thinks this through, Jaro’s explanation will eventually overcome those radiophobic tingly feelings.
“Can you explain the anomaly?”
He cannot, but that wont stop him from vomiting this BS up again….and again…..and again.
Gorleben is on the west bank of the Elbe, the former dividing line between West and East Germany. Downwind is to the east, yes?
I would look to former Soviet style manufacturing as a potential cause of birth anomalies.
Possibly nuclear power plants would be better off with much smaller security forces?
@David E. Benson
They’d definitely have lower operating expenses.
Just so people know, Bas has aired Scherb’s fraudulent studies about altered sex ratios due to radiation many times on this site, and they have been thoroughly refuted in other comment threads. In particular, the claims about sex-ratio changes near the nuclear waste depository at Gorleben have been debunked in detail, especially by RR Meyer’s excellent analysis. (https://atomicinsights.com/former-nrc-counsel-attacks-quoted-source-used-in-radiation-isnt-the-real-risk/ ) .
That’s how Bas operates. He makes outlandish claims based on a handful of junk-science studies by Scherb (which are indeed sometimes published in peer-reviewed journals and cited by government authorities, more’s the scandal). When these studies are demolished by knowledgeable commenters here, with great effort and meticulous care, he simply waits a while, then brings them up again in a new comment thread without any reference to the previous exchanges in which they were discredited. That’s pretty sleazy.
It’s child’s play for Bas to spew out the same frauds by junk-researchers over and over again, while it’s an exhausting, Sisyphean task for honest people to uncover and expose the myriad errors and deceptions that these frauds are built on each time he rehashes them. That’s why propagandists like Bas tend to win the day through sheer repetition of lies. People reading Bas’s comments should take all this into account.
Thanks for that reminder Will. I won’t bother responding to Gresnigt’s reply to comments I made wherein he again cites a Scherb paper.
And don’t forget that a few (several?) years back Cooper of Vermont School of Law notoriety made an overture to BAS on these fora that looked very much like a prelude to a job offer.
Thank you for reminding me why I had previously banned Bas from commenting here. During the past month and a half or so, most of my waking hours have been devoted to being the best darn Gramps I can be. I haven’t been reading Bas’s comments very carefully.
I’ve deleted all of Bas’s comments on this post. That action also deletes all of the excellent responses provided.
Possibly not the best form of censorship.
@David E. Benson
Private citizens cannot engage in censorship. Bas is free to establish his own outlet for his odd notions. I’m not going to allow him to spread his stuff here any longer.
If anyone is interested in his thoughts and some good response to them, they can feel free to visit https://atomicinsights.com/former-nrc-counsel-attacks-quoted-source-used-in-radiation-isnt-the-real-risk/ and its attached comment thread.
You missed deleting some of the subthreads and Bas-posts. My original response to Bas “Reliable scientific citation required” now appears as if it were responding to Meredith, which isn’t fair on her at all!
Sorry for somewhat off topic comment, although it’s still about SFPs and the cladding fire bogey man.
As discussed in the article below, none other than conservative/GOP DOE Secretary Rick Perry suggests that we could have a Fukushima like event in the US, due to the fuel in SFPs, if we don’t resolve the waste problem (e.g., build Yucca).
This is one of many cases I’ve seen where people have tried to use fear mongering arguments in order to “help nuclear” by getting people to accept Yucca, etc… Such actions are very problematic and counter-productive. The industry doesn’t need “help” like that.
It should be obvious to intelligent people by now that nuclear fear mongering arguments in general do not help nuclear win public support in the long run. Also, if you try to argue for moving Yucca forward by talking about the horrible risks of spent fuel, wouldn’t that just make the people in any regions that may consider hosting a repository that much more hostile to the idea?
Perry’s statement is bad enough, given the above general/philosophical concerns, but it is even worse given the blatant inaccuracies, i.e.:
Lack of a repository does not result in more pool storage, it results in more on-site dry cask storage. Even if Yucca moves forward, it will be a long time before the pools are emptied. All it will do is possibly avoid some dry storage.
Also, he even seems to suggest that the SFPs were damaged at Fukushima, or that they contributed to the release. He appears to agree with Von-Hippel, et al, in his suggestion that an earthquake could cause an SFP cladding fire.
It’s pretty distressing that such things would come from a DOE Secretary, especially a GOP-appointed one. Almost makes me wonder if this is part of a subtle plan to talk about supporting nuclear, but actually hampering it so that fossil fuels (that they actually support) can increase their market share.
There is no reason that I know of to believe that Perry will support nuclear and every reason to believe that he is in natural gas’s pocket. He was the governor that lead to Texas blowing $10 billion+ in rate payer money to build transmission lines to West Texas. That never gets factored into the cost when folks brag about cheap Texas wind. I’m sure he helped a lot of people who wanted to start subsidy farms (AKA wind farms) and who wanted to burn more natural gas.
On the same theme, there are some advanced reactor fans that make a fearmongering deal out of spent fuel in much the same way. Also not helpful, and actually unlikely to advance their cause, since public fear of nuclear power generally doesn’t respect technical boundaries.
Amen, brother. Couldn’t have said it better.
Although historically they have not fear-mongered SFPs and (more generally) on-site storage that much. In fact, they generally like the idea of on-site storage (or centralized interim storage) as a way to avoid placing fuel in a repository (despite the fact that retrievability is a requirement for repositories).
They tend more to fear-monger the (actually negligible) long-term risks of leakage from repositories. You sometimes even hear them say that “we don’t know how” to isolate spent fuel for long time periods. We don’t have the tech. What BS. Many if not most of man’s other waste streams actually pose a larger hazard over the very long term. Not that anyone cares….
Furthermore, they are naïve enough to think that reducing the longevity (half-life) and bulk of the waste somewhat will significantly reduce the (purely political) difficulty in siting a repository. They are clueless about politics and public psychology, and the real sources of fear and opposition. Hint, if the public and politicians were quantitative and scientific(i.e., if those half-life and volume numbers meant anything at all to them), there wouldn’t have been any problem in the first place, even for a once-through repository. Another hint, look up the public/political reaction in the Dakotas to DOE’s humble proposal to merely study the idea of deep borehole disposal of capsules containing pure Sr-90 (30-year half-life) and other such fission product isotopes (i.e., the final products of even an ideal closed fuel cycle).
Kinda like the push for “safer” advanced Nuclear Reactors…..
Wait….the reactors that were built in the 60’s and 70’s are incredibly safe. I understand the point of labeling them “safer”, the problem I have is that phrase seems to automatically makes today’s Reactors “unsafe”.
I believe there was a huge mistake made as we learned more about how to keep building safe reactors. Instead of aiming to make them “safe” than existing designs, we should have aimed to keep them just as safe, but a lot less expensive to license, build, operate and maintain.
You folks that voted for Trump are patsies. He ain’t gonna ride to NE’s rescue. And any fool could see it when he stacked the deck with fossil fuel pimps like Perry. The man is a pathological liar, about everything. He’s running a con, and Perry’s appointment underscores that fact. What does Perry know about NE? Not much, obviously, if his prior lack of knowledge about the functuon of the DOE is any indication. Any discussion about pertinent NE issues, such as spent fuel pools, is a waste of time with this administration in power. Policies are not established out of concern for science, the public’s welfare, or anything other than the profits of special interests, and the ego of the sick and deranged wack job in the Oval Office.
Once again, I did not vote for Trump. I accepted the fact that he was elected by the people of the US following the well established rules under which we hold elections. I believe it has been terribly destructive for his opponents to paint the process as illegitimate instead of simply functioning as an opposition party is supposed to function in our system of checks and balances.
I do not expect Trump and his appointees to purposely elevate nuclear energy above other sources. I do expect that with skillful communications efforts, nuclear energy should be able to achieve a more level playing field that will allow it to flourish if the engineers, managers, operators, etc. step up their game and learn how to be competitive energy suppliers.
Von Hippel’s and Lyman’s recommendation that old spent fuel be removed to dry storage is odd. Surely they must be aware, it is only the new fuel that can heat up to such extent as to release activity. The old fuel just doesn’t have sufficient heat source to cause fuel failure, even with total loss of all pool water. This has been known for a long time.
In fact, more recent research with better heat transfer codes confirmed this result once again, and also proved that placing the old assemblies around newer, hotter ones, will be a large improvement in terms of cooling. The old assemblies basically act as heat sinks/cooling fins for the hot assemblies in a pool draindown accident.
@ Cyril R.
While it’s true that “The old assemblies basically act as heat sinks/cooling fins for the hot assemblies in a pool draindown accident,” experiments at Sandia have demonstrated that a fire in the hot assemblies eventually heats adjacent old assemblies enough to set them on fire as well.
In this way, the entire inventory can burn.
Thanks Jaro. I do not doubt that 11 day old spent fuel assemblies will fail in a total draindown accident. This just proves my point. It’s the fresh spent fuel assemblies that are any cause of concern.
However, having cold assemblies around, like other parameters such as density of the rack, rack design etc. can help reduce the time after exposure at which fuel will not fail anymore in a draindown accident. Still I don’t doubt that 11 day old assemblies can be made to be ok after total draindown.
Probably the best thing to do is have the newest spent fuel assemblies in a small, dedicated rack having low density and lots of space for air cooling (possibly fitted with cooling fins if/as required). This would have passive air cooling ability. This rack wouldn’t have to be big – just the latest off-load, probably sized to ~1 full core. The older FAs can be easily laid in a high density racking with some simple checkerboard or other arrangement.
7 billion is overpriced for simple casks. Yet in a more important way, it is pretty cheap. US nuclear power output is over 90 GWe average.
7 billion in solar PV installations would barely get 1 GWe average output. And no cost included for managing the e-waste of solar panels. Some solar companies are claiming they will take responsibility for the e-waste, but little financial commitment is made to it (unlike in the nuclear industry where a large sum of money has been set aside).
Even in the future will dramatic cost reductions in solar, 7 billion would barely get 2 GWe of average output.
Ugh posted in wrong thread. Sorry.
Can I ask what kind of dose rates would be seen around (outside) the plant exclusion area boundary if there were a hypothetical spent fuel fire? Would the dose exceed 2 mSv/day?
That’s actually a really interesting question, and seeing as nobody else has replied I’ll have a go, even though the thread is a little old now. The first important point is that a fire in a spent fuel pool is totally unrealistic and basically impossible in real world conditions. This means there are no credible accident scenarios involving spent fuel pool fires where any elevated doses would be received at the plant boundary.
Moving on to incredible accident scenarios it is possible to get volatile radionuclides in the spent fuel to become airborne. Without a significant source of energy (like the graphite fire at Chernobyl) most of the nuclides won’t make it very far. If you twist the parameters enough you can end up with the Cs-137 in the spent fuel becoming airborne then deposited just over the plant boundary, which would give extremely high radiation doses. Exactly how high depends on various assumptions about the accident, but given we’ve made it this far you could easily select a fanciful situation and make dose rates at the plant boundary many gray per hour.
I’ve never heard a vaguely credible accident scenario for a fire in a spent fuel pool. It would require both damage to plant systems and loss of access to the plant for well over a week, without being so bad that the disaster itself causes the spent fuel to be dispersed into the environment before it can catch fire. This rules out terrorism, reactor accidents and natural disasters. The least unbelievable spent fuel fire scenario I’ve thought of is this:
1. a small volcano erupts near a reactor without any warning
2. all plant operators are immediately incapacitated
3. an initial earthquake somehow disables the redundant water supply systems to the spent fuel pool
4. the ongoing eruption produces enough ash and carbon dioxide to stop aircraft from accessing the plant
5. a lava moat around the reactor prevents all ground access
6. somehow the reactor building is strong enough to stop the pool from filling with ash but then allows free escape of volatile radioactive material once a fire starts
I thought twice about including my scenario of most concern for a spent fuel fire as I didn’t want to scare people, but I think it’s important to get the information to the public. Also, I managed to include a lava moat – once I figure out where to add some dragons it will make a decent dystopian fantasy novel!
But what would be the dose rate downwind? Would it exceed 2 mSv/day that is considered the chronic limit for health damage? This seems very hard to do with Cs137, even with Cs134 included. But perhaps if it happened with a few weeks old fuel, there would be some radio-iodine isotopes and tellurium isotopes?
Tough to say what the actual dose rate would be, but it could be very high. It’s such an unlikely situation it’s not really worth the effort to calculate in detail, so the only people who have actually calculated downwind radiation doses tend to be very anti-nuclear. This generally means that their models have been set up to ensure any contamination will spread over as wide an area as possible rather than being concentrated near the fire. As a result, lots of people get an elevated radiation dose and the number of people who would be evacuated is maximized, but the maximum doses end up lower than expected.
Still, Alvarez et. al. calculated maximum doses over 200 mSv per year in a wide dispersion model (see https://www.nrc.gov/docs/ML1209/ML120960695.pdf). By changing parameters to ensure that more contamination is deposited close to the fire it would be easy to increase the maximum calculated doses by an order of magnitude or more, taking them well above 2 mSv per day. It’s never going to happen, but if it did then doses could easily get to the point where people actually get hurt.
The sequence of events that would have to happen to produce both harmful doses to even a single member of the public AND widespread contamination are mutually exclusive. For example: If there are substantial areas where the concentration of isotopes is high enough to cause harm for anyone who remains for days, why would they still be there? Even simple survey instruments would indicate the danger.
If the pool drains slowly, a lot of heat has to be moved out of the pool in the form of evaporated water. That limits the temperature rise. If recently removed fuel is concentrated in a small portion of the pool, that section can theoretically smolder, but the rest of the pool would be far too cool to be a concern, so the source term should not be the total inventory of Cs-137.
Since we now know that concrete pumper trucks, which can be delivered to any US nuclear facility in a relatively short period of time from local resources, can fill even elevated pools that have drained enough to cause high local radiation fields, why would any operating crew ever let fuel pools reach a condition in which large scale release is a problem?
Rod, I think one of the concerns is that there is a leak (maybe from beyond design basis earthquake?) of such size that it exceeds the make-up systems capacity to keep the level up.
Unless the makeup system is a spray type (which I would have done probably if designing this sort of system), uncovery of the fuel would be hard to prevent.
Do you know more about the construction of the pool and liner? Presumably there is space between the liner and the concrete structure. And around the concrete structure, other cells. (talking about BWR here not PWR). Does the leak just flood up those other cells until they are filled up and then does the leak stop? If so then the makeup system could still be useful. If the leak continues indefinately (because the other cells aren’t leak tight for example) then an uncovery situation could be possible.
Personally it seems a little far fetched; if you know something about the ductility of annealed 300 series stainless steel, you’d agree that large ruptures or tears producing leaks exceeding makeup system capacity are not really credible. A small weld tear or pinhole leak is quite credible but of such small leak rate to be of no consequence even without makeup for days.
Still it would be useful to know the dose rate from the postulated fire. Agree that it would only affect the hottest fuel assemblies – probably less than 1/3 of a core in source term. Still there is iodine in 10-20 day old spent fuel so that has to be considered.
I couldn’t agree with you more. Honestly, for every slightly realistic accident involving spent fuel that I’ve looked at there has been no chance of an elevated dose to any member of the public. Even a small scale release is beyond anything that could plausibly happen. A release from a fire requires such a complex and exact mix of bad luck, negligence and weeks of inaction by all external parties, that it just won’t happen. Even if there was a fire in a spent fuel pool, most of the fuel won’t be damaged, and some (maybe even most) of the material released will stay in or around the pool because there isn’t going to be a huge fire or explosion to help disperse it. Then after all of that, there would be such a long time between the start of the incident and a hypothetical release that people could pack up and evacuate in an orderly manner well before any release of radioactive material.
Just curious – have you ever considered writing up your findings? Unfortunately, I have gathered the impression from years of reading journals that physicists are taught to avoid claiming anything is impossible.
I have no such compunction. For example, I am positive that it is impossible for me to dunk a basketball into a standard elevation hoop without some assistance that is not a part of the game of basketball.
I’ve heard about people having freak strength during dire times (lifting cars off people)
You don’t believe a person can have freak jumping ability?
What about my 30 lb RP meter car that is required to have 3 out of 4 wheels chocked when not is use. You don’t think my cart, in the event of an earthquake, could bounce around and hit the “meltdown” button?
Maybe I’m confusing this with Superman. You really have to work at a Nuclear Power Plant to understand how incredibly over cautious and over complicated this industry is. Even with simple things…..like a cart needing to be heavily secured even though its not even close to safety systems.
Maybe there is such a thing as freak jumping capability. What do you think the chances are of me getting that ability while on a basketball court and holding a basketball?
Since you only know me from my writing, it might help you determine the probability of that unlikely series of events if you know that I haven’t been on a basketball court with a basketball in my hand in several years. During the majority of the past 40 years – since high school graduation – I haven’t been on a court for more than 30 minutes at a time a few times per year.
“articulated boom pump truck”
Rod could have been a consultant for Pandora, the most entertaining, if not realistic 😉 , nuclear power plant disaster movie since The China Syndrome.
( http://www.rottentomatoes.com/m/pandora_2017/ )
I do not understand your comment. If it’s humor, it’s too subtle for me.
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