Sensible recommendation: 100 mSv/month – As High As Relatively Safe
Dr. Wade Allison, the author of Radiation and Reason, was interviewed following a recent visit to Japan. He has a rational recommendation for the international radiation protection community – instead of setting radiation dose limits based on keeping them as close to zero as possible, why not choose levels that are based on keeping the hazard to human beings within reasonable levels.
It seems apparent to me that people accept many minor hazards because they recognize that accepting a little risk can make life richer. Instead of seeking to tighten rules on fossil fuels or other energy alternatives to the standards achieved by nuclear energy, why not ease the rules on nuclear energy to point where it poses a hazard no greater than what has already proven to be acceptable for its competitors?
All is a matter of risk taking as the Dalai Lama pointed out to those assisting at the speech he gave in Fukishima on the benefits of nuclear for the poorest on the planet. Those who chose to get here and eat the snacks & drinks offered took some risks, he went on to say!
I see the hysteria about anything radioactive as part of the “health movement”. It’s been building over the last 10 years and it’s the phenomenon of wealthy people, most of them with 1 child per family, becoming obsessed about their health and especially their child. They single out ingredients in food products that they think are a conspiracy to make everybody unhealthy, they reject too much science in food, want it to be “organic”. Generally, they don’t trust any official report and have prejudices and suspicions about big corporations. When these people are subsequently confronted with well-designed propaganda by the anti-nuclear groups, that appeals to precisely these suspicions and prejudices, they immediately join the choir “no nukes” and buy gas masks to protect from “hot particles” that might have made it across the entire Pacific Ocean and several mountain ranges.
All this flies in the face of where our wealth originally came from: it came from courage and hard work, both of which might very well be harmful to health. But it was understood that health is not everything, we want to achieve more than just be alive and functioning, we want wealth of other forms, and these might be more important to us than transient things like health.
Given the choice between good health and a cheeseburger, many people still prefer the cheeseburger.
This is absolutely on the money. You literally took the words out of my mouth. I thought it was bad in the US, but I would say in Canada (where I am working these days) it is worse. Most grocery stores here have an aisle of yogurt that is 40 feet long. At lunch the topic of discussion is always whether a brussel sprout or organic carrots are ‘healthier’. The whole thing is more than a little narcissistic I think. As you say it is a function of wealth. Western countries are extremely risk-averse these days (of course risk is not assessed very accurately). It’s one reason my real hope for nuclear renaissance lies with China. I just hope they are not cutting too many corners and end up with a problem.
We have to look at it objectively and realise that health is just one of many aspects of our standard of living, and that it costs. The environmentalist movement is following the same pattern, only that it prioritises the environment instead of health. Both movements go very well together.
Both movements use the same tactics.
Both movements are as much about presenting solutions to problems.
Both fail to properly consider if their is even a problem to start with.
Both fail to properly consider the effects and consequences of their solutions on the systems related to their problem topic.
Both do have good ideas and bad ideas. The good ideas tend to become the norm. Yet the norm is often seen as corrupt by these people.
Speaking of money, there’s a lot of money to be made here. Almost all of the “health movement” stuff is due to marketing, and the middle class — particularly the upper middle class, with more disposable income — gets the brunt of the attention. Thus, it’s not surprising that they are ones exhibiting most of the silliness.
Unfortunately, the marketing is helped by a substantial amount of low-grade science that purports to show that this is unhealthy or that is healthy, usually based on the flimsiest of evidence. These marginal studies then get inflated past their worth by unscrupulous people trying to make a buck, whether it’s through selling a book or selling a certain type of food or other product. An entire niche industry exists for this purpose, consisting of public relations companies that play up this stuff, ostensibly in the public’s interest (and often through a front group), but meanwhile they’re being paid for their work by companies that are hoping to profit on the latest scare or fad.
How many people remember all of the awful breakfast-cereal commercials that we had to endure on TV a couple of decades ago, because a couple of marginal studies claimed to have found “important” health benefits from a high-fiber diet? That fad has come and gone, but we can still laugh at the Saturday Night Live spoof of it, Colon Blow.
I remember the emphasis on fresh food and blenders, highlighted by the SNL skit “Bass-o-matic”: http://www.youtube.com/watch?v=0BQFv83QJ2Y
I wonder if the ageing population and/or low birth rates of Western countries is the root cause of this risk aversion…
Somebody slap Rod upside the head with a slide rule. What kind of sorry SOB want to reduce standards when we have proven that we can easily meet them. It is not acceptable anyplace in the power industry to hurt people.
The power industry has an excellent safety record and produces electricity for Americans with insignificant environmental impact. Every year we get better. I like to think that the nuclear industry leads the way and that excellence is contagious.
Here is what people who never learned to use a slide rule do not understand, once it is insignificant it does not matter if it is even less significant. There is no difference between very small numbers when we are talking about risk. The risk of dying is 1.0000. The risk from nukes is 0.0000000000001 and the risk from being hurt by a coal power plant is 0.0000001. These are the same number 1.0000000000001 and 1.0000001.
In the context of a corrupt USSR, I can show that mathematically that not having a containment building is economical. So Rod do you find it ethically acceptable to expose children even if the risk of core melt is insignificant?
Here is what I know. Containment buildings are not all that expensive if you can make them last 60-100 years. Just for fun compare the cost of cleanup at TMI to the Kingston coal ash cleanup.
What is the cost of operational excellence? You make bigger profits because it lowers your cost.
What is the consequence of the decisions that we had been making? What is the consequence of the risk? Just because something can be done does not necessarily make it the “right” choice.
You are right operational excellence is imperative to ensure adequate capital recovery. It lead us fro 70% to 90% capacity factors. Doing it right the first time is the best choice.
There is a difference here that we and I mean all of us have gotten our wires crossed about. What level is safe enough? This goes back to our series of posts about the LNT model. What is the consequence of our assumptions with that model?
Let’s take an accident scenario where the core is relocated and mostly melted. Would you prefer to have the containment intact as a barrier that you can close when you are ready or do you want to have the containment breeched and unable to contain the fission products. WASH 1400 identified that the small break LOCA posed the largest risk to core damage. Ok does having a vented containment negatively impact that scenario (probability of 10-4 to 10-5 ish) What is the risk that the population is exposed to. If you listen to the likes of Bob Applebaum it will be disastrous. If you adopt a threshold then the risk is nothing.
In order to be able to make effective designs and procedures the risks have to be fully identified. In the situation where one risk is completely misguided (LNT) it forces us to assume real risk to the operators and the safety of the plant (Fukushima) by not having vented containments.
Ask yourself without any prior prejudice, what would nuclear power look like if we had not adopted LNT and had accurately identified our risks.
The USSR designs were the way they were because they didn’t have any value for the life of a human being. There is a saying “Doing the right thing for the wrong reasons is still doing the right thing.” The RBMK design is an aberration to begin with. It blew up because of that. The force behind the explosion would have challenged even a very well designed containment.
Rod and I are not saying do not have a containment. Far from it, we need a containment, but keep the containment vented to reduce any pressure build up. The operators then have the option to isolate the containment after containing the casualty. The containment serves to contain the fission products in bulk which if they are contained allows the operators to access the necessary portions of the plant to combat the casualty.
It is in the economic interest of the owner of the utility to operate the plant safely and reliably (these are synonymous in my mind). The market forces in the western world force our reactors to be safe. USSR did not have that requirement.
Rod is simply proposing making the standards match the risks.
I never used the word or the intent of “disastrous”. Releases are not “disastrous”, but the effects are not zero either.
The EPA uses a consistent 10^-6 to 10^-4 excess acceptable lifetime cancer risk for a huge number of toxins, radiation included. Seems fair to me, why should nuclear be allowed to socialize their costs more than any other industry?
Looks like the fossil fuel industry has an EPA exemption:
How much did the industry pay for it?
How much will society pay for it?
I am interested to hear how nuclear power socializes its costs.
EPAct 2005 was the first time that any subsidy was ever granted to nuclear power. The PTC is the only socialization that is out there.
Price Anderson creates a pool of cash ~20 Billion to cover a major accident. I have feeling Japan will be around that number. So any accident damages to the public is covered within an order of magnitude.
The fuel has a fuel surcharge that built 75% of Yucca mountain. The remaining 25% came from the DOE. The DOE was slated to fill 25% of Yucca Mountain with the remaining 75% from commercial waste. So fuel disposal costs are covered. (side note I think it is crazy to throw away perfectly good fuel.)
The costs of construction is borne by the ratepayers who benefit from the power. It is an investment. Once the power plant is paid for 25-40 years, the rate payers only pay for the marginal cost of electricity. Sounds like a rational investment by a state to encourage building nuclear power plants.
The other aspect is loan guarantees. Unlike Solyndra and others, Southern Company had to pay such high subsidy costs that they almost went with private equity to fund construction. The risk of default is shared by those seeking the loan. The GAO specifies the level of the subsidy that has to be paid. Southern Company’s books are a little different than just about any company that is out there today.
So Bob, the only socialization is in the subsidies under EPAct 2005. Please be more specific with your comments. If this is what you are referring to I agree with you. If you are implying something else, then check what you say.
The 20 billion from Price Anderson is paid by the consumer of the electricity through their rates. Thus it represents an internalized cost. Similarly the spent fuel surcharge does the same. Obama and Reid just reneged on the NWPA 1982.
More than the direct competition – the coal industry?
The Fukushima containments had venting valves and pipes installed, and these were used.
The problems with it are as follows:
1. It is fully manually operated. AND the politicians decide when to vent a containment.
2. It vents to the upper building. Venting hydrogen rich gas and fission products to a confined non-armored space has got to be the dumbest idea ever. We can just be honest about that. This design choice does appear to be an artifact of the silly LNT and ALARA which in this case have turned out to be penny wise pound foolish.
In stead, what should have been installed was a simple pipe in the shape of a U, filled with water and with filters installed on both ends. One end of the U pipe sticks into the containment, the other sticks outside. Increasing pressure pushes water down, opening the filtered vent path. This is a fully passive system and is redundantly filtered with HEPA and carbon filters. Radioactive emissions could have been cut a thousand fold with such a simple system.
I think we can be honest about Fukushima. There were important design flaws in the venting system, the hydrogen control, and the electrical infrastructure. I suggest to make the changes to existing and new nuclear plants where necessary and move on with the nuclear build.
Cyril it sounds like you do not understand the design at Fukushima. Read the INPO report and pay particular to ‘Figure 4.4-1 Unit 4 Standby Gas Treatment System Hydrogen Flow Path’.
Cyril, we agree, all nuclear plants should have accident rated vents with filters. See #5. That combined with igniters to prevent H2 explosions should reduce the worst case consequences of nuclear accidents to levels far lower than the routine operation of fossil plants.
Maybe I’m slow this Monday morning but you seem to be arguing against yourself, Kit.
Once the nuclear industry is safe enough, it doesn’t make a worthwhile difference to push it to be even safer. The acceptability of hurting people is no longer the issue – no people are being hurt. This is the valid point you make with your digits of precision.
Applying this to the nuclear industry, how safe is safe enough? My assessment is that we have already passed the point of useless improvements. Indeed the danger now is that nuclear power plants will be forced into doing expensive things that make no difference to real safety (except in models of extreme events that are basically limited in how far they can be believed anyway).
While I do not think that Chernobyl was solely the result of the specific events on the night, I’d remind you that the reason they put the reactor into its highly unstable state was to perform a “safety test”.
Making electricity has been ‘safe enough’ for at least 20 years in the US but no regulator is going to allow anything but the best available technology (BAT) for new plants. All new power plants are expensive including fossil plants with pollution controls.
Many of the new features that make a new nuke expensive have nothing directly to do with safety. If we can make the fleet of plants designed for 40 years with an 80% capacity factor last for 60 years and 90% capacity, why not design those features in to get a plant that will last 100 years with a 95% capacity factor and higher thermal efficiency?
Improving reliability has up front cost but there is payback over the years. Reducing the number of initiating event has the modeling effect of reducing core damage frequency.
What part of bigger do you not understand? If you ever tried to work on a car in a garage that is too small you know what I mean. Bigger containments not only allow for easier maintenance but keep the concentration of hydrogen concentration lower after an accident, as a result Passive Hydrogen Recombiners, may not need to be safety related. Higher initial costs but lower lifetime coasts.
One more example, I am responsible for a safety system that only has a safety function and is the essence of simplicity. On older designs, a much larger and more complex system that was used for normal operations is also was used for that safety function. A royal pain in the rear end and a human factors nightmare. Again higher initial costs that results in lower operating costs while reducing the core damage frequency in the model.
So you can compare the operating costs of a 40 year old coal and nuke plant that are ‘safe enough’. If you are going to build a new power plant, the coal plant is going to have state of the art pollution controls and the nuke plant is going to have a mitigation strategy for a molten core burning the reactor vessel head for example. If you are making an economic choice, compare new to new based on the current regulations.
I think that new nukes will prove to be the economical choice without lowering standards.
Excellent examples, Kit, of the push for excellence, and the often-unforeseen benefits of controlling activities closely.
I don’t have a problem with improvements – especially when those come with a reliability benefit. I have a problem with regulations that require levels of safety beyond what is useful in detailed ways that sometimes do not leave the field open for kind of improvements you discuss. Like say a bigger containment – that needs years of regulatory review and is held to standards of pressure containment that it physically cannot experience.
But I think we actually mostly agree on this topic.
More relevantly in the context of Professor Allison’s thesis, it is the regulations in times of accident that need real review. ALARA is all very well for designing normal operating environments, but we need to be able to switch to real risk numbers when facing a crisis like Fukushima, and make sensible judgements about mass evacuation and cleanup techniques.
And let us not forget that Chernobyl was a military installation disguised as a civilian plant.
That’s not quite true. Yes RBMK reactors were used as breeders for PU at one point, but that had stopped by the time the Chernobyl power plant was built. The Soviets had moved to dedicated breeders by that time.
I remember that info either from Sen Domenici’s or Bruno Comby’s book. But I do remember that those were for military purpose. But you may be right.
No. Chernobyl was a civilian power plant whose design was based on a military development program. It wasn’t a military site, and that kind of conspiracy thinking will obstruct the learning of useful lessons from that disaster.
I just reread Comby’s chapter on Tchernobyl. He does not address the military dimension. I’ll try to find Sen Domenici’s book. It has to be from his book.
Joffan is correct. The RBMK is a scaled-up version of a weapons-production reactor. It was an easy short-cut for the Soviets to develop electricity production from technology that they already had developed.
Although based on weapons technology, the bigger design was used to produce only heat and electricity, and I have yet to find a credible reference that indicates that these reactors were used for anything but this purpose.
Ok. I’ll go for DVX and Brian’s explanation for now
… And Joffan’s.
Let’s cool it. We should not make the mistake that the frightened anti-nuclear lobby makes. The problem that the Japanese have is that they do not trust one another on nuclear matters. Let us explain the truth (the medical facts of radiobiology and clinical radiology) and build on it to make confidence and understanding (as many have on how to be sensible with UV when on holiday in the sun). Arguing with the frightened is a waste of time. Stop slagging them off, they do not understand. Have a look at my pre-Fukushima book “Radiation and Reason: the Impact of Science on a Culture of Fear” and website http://www.radiationandreason.com If we work at explaining why antinuclear is wrong, it will be like smoking, one day public opinion will switch almost overnight. In the UK at least we are not THAT far away from this point, I believe.
When we explain the medical facts of radiobiology and clinical radiology (as well as epidemiology) we end up with LNT.
That’s where we are.
No, we don’t. We end up with some weird hybrid that uses a “magic” factor called DDREF to avoid admitting a threshold. That means that the so-called linear no-threshold model is no longer linear with high dose effects and so has no justification.
ICRP admitted as much in the extract of their publication 99. http://www.icrp.org/publication.asp?id=ICRP%20Publication%2099
“Unless the existence of a threshold is assumed to be virtually certain, the effect of introducing the uncertain possibility of a threshold is equivalent to that of an uncertain increase in the value of DDREF, i.e. merely a variation on the result obtained by ignoring the possibility of a threshold.”
Without DDREF, LNT is falsified by the evidence.
DDREF isn’t magic…it’s an observed phenomenon. Biological damage depends on the total dose and the rate that the dose is delivered.
That’s called science, not magic.
No, Bob. DDREF is not an observed phenomenon. It’s a model adjustment to attempt to account for the observed phenomenon that LNT does not work at low doses.
It is an indicator that LNT is wrong at low doses, but that people are not willing to admit it. The use of an arbitrary factor does not mean LNT is still valid, as you like to think. It introduces a gaping discontinuity into the model that is a clear indicator of a broken scheme.
For my curiosity, are you aware of any study that compares data for people from Ramsar or the other oft-cited regions with naturally high background radiation that matches up with an LNT model?
All of those types of studies that I’ve seen are ecologic in design, not cohort studies. “By design” they won’t match the LNT model.
However, in other study areas (like A-bomb survivors, residential radon, etc.) where the epidemiological study is designed as a cohort study, you get agreement with LNT.
Of course, there is always a gap between zero (the origin of the graph) and the lowest point on any observed curve. This is true of many toxins, not just radiation. That’s because epidemiology is limited statistically. That statistical gap will always be there, we’re 100% certain of that.
It takes a preponderence of evidence to be convinced it is also an effect gap. Such evidence does not exist.
Bob, are you saying that there is no way to design a study that could show LNT via a study of the populations of different locations with varying degrees of background radiation?
No, it could be done. But it would be very expensive. That’s why it hasn’t historically been done.
“All of those types of studies that I’ve seen are ecologic in design, not cohort studies. “By design” they won’t match the LNT model.”
This makes absolutely no sense.
Under the LNT model, if one person gets 10 mSv and another zero, the total risk is the same as if one person got 5 mSv and the other also 5 mSv (and any other combination of doses, as long as the collective dose is the same). Therefore if LNT holds, we should get the same result regardless of the distribution of doses in the population.
Conclusion: an ecological study cannot determine the true dose response, but it can disprove the LNT hypothesis.
Shhh … don’t confuse the issue with mathematics!
Don’t you realize that preponderance of the evidence clearly indicates that the world is linear unless ecological studies are involved?!
Your example proves the point…in an ecological study, the two populations you’ve described would have an average dose of 5 mSv ((10+0/2)=5 and (5+5)/2=5).
It wouldn’t matter how the cancers appeared in these two populations. You couldn’t infer an LNT relationship because the average doses are 5 mSv and the cancer outcomes are either the same or different.
Nuclear is and should continue to be the safest energy source for electrical power generation. Having said that, the safety aspect needs to be weighed carefully. What I see is that the supposed safety regulation for nuclear has been carried so far that it makes power plants difficult and expensive to build. The consequence is that instead of building nuclear power plants, other types of power plants are built or continue in operation, all of which are more dangerous. The result of the very high level of nuclear safety is a net reduction in safety for electric power. I fail to see the superiority of this.
This is the pro-nuclear argument that seems from my viewpoint to be virtually impenetrable.
The whole point of regulations that demand that every nuclear plant be gold plated when it come to health and safety is that it will make them too expensive to compete.
Fossil-fuel interests knew that they didn’t have a hope of competing with nuclear, so they leveraged Cold War fears of fallout and radiation (which themselves had been overblown to serve political ends) to lobby for increased regulation often through PACs that they funded.
At an average, we have 200g of potassium in us. this includes 35mg of radioactive K-40. Those of us, who are more “health-conscious”,take “light” salt with 15% potassium chloride.
Just like temperature, there is an optimum amount of radioactivity which is good for us. It is time the medical community came out with optimum and maximum safe radioactive levels.
What we need to be doing is to choose the least risk alternative.
Evacuating people over 20 mSv/year kills many; tens of people died in just one hospital in Fukushima district, simply because it was abandoned.
When to evacuate an area? When the alternative, letting people stay, is highly likely to kill more than evacuating people.
We must also be consistent. Major cities, industrial areas and highways kill hundreds of thousands each year by air pollution. Yet we don’t evacuate major cities, people near major roads or industrial areas.
Not that this is for NORMAL operation of said cities, roads and industrial complexes. In offnormal (accident) conditions, many more die. But surprisingly few die in accidents; almost all die from cancer, lung infections etc. caused by the NORMAL operation of cities, roads and industrial complexes.
We couldn’t practically evacuate all major roads, cities, and industrial areas, and even if we would attempt this, millions would likely from the attempt.
A more solid choice before us is what type of power plants to build. Nuclear plants directly substitute dirt burners, saving many lives. If Fukushima Daiichi nuclear complex had not been built, and in stead a coal plant had taken up its place, how many would have died from air pollution?
Coal has a best (lowest) case death rate of 15 deaths per TWh. If less than optimal abatement is used then the number goes up an order of magnitude but let’s be kind to coal for now.
Fukushima Daiichi has generated 877 TWh over its lifetime:
Thus, 13000 people have been saved from (almost exclusively) air pollution deaths.
So far the radiation death count from Fukushima is at zero. Some workers have regrettably died falling out of cranes and drowning and dying through exhaustion. Nothing to do with radiation, everything to do with dangerous earthquakes and dangerous tsunamis and working in a natural disaster struck area.
However fear has killed tens of people already – those poor abandoned souls in the hospital. There are likely many other such fear related deaths. Even if, somewhat unfairly, those fear related deaths are added to Fukushima Daiichi, it is still much safer than 13000 air pollution deaths from the coal option.
Source for deaths per TWh:
I strongly disagree with my Brother Rod, here.
This not the way to win hearts and minds. It’s just the opposite in fact.
I’m not talking about background radiation levels. They certainly should be adjusted TO a safe level…which has to be discussed by health physicists and doctors and engineers and so forth to whatever level is reasonably safe and makes the public *feel* safe. We can’t have only technocratic answers and solutions to making the public safe. They have to *feel* safe as well. So clearly the very low tolerances pushed by some for background radiation needs to be adjusted upward.
But that’s different than looking at safety in general. I’m *against* the idea that stainless steel piping welds don’t get full nuclear non-destructive testing in nuclear plants simply because stainless steel piping in fossil plants don’t.
I’m against the idea that security at a nuclear plant should be the same as that as my old gas plant, 1 65 year old guy, unarmed, from a rent-a-cop agency.
I can go on an on based on this *method* unless someone wants to argue, and we can discuss it, that nuclear plants only need to be as safe as fossil plants, which I think is truly insane.
Walter with the reason to disagree brother Rod is that he is wrong. A large break LOCA will damage a certain about of fuel which is why containment leakage is an important consideration. Off site doses limits are based on normal operation, abnormal events, and postulated accidents. If an accident occurs the public needs to be protected without evacuation. A very reasonable expectation on the part of the public and clearly within the ability of the nuclear industry.
At Fukushima there was a ‘beyond design basis event’ which led to a ‘severe accident’. At this point, ‘sensible’ exposure limits become the rule. Western nuke plants are designed for ‘beyond design basis event’ but to a different standard considering emergency plans that call for evacuation.
The short answer is we do not design for very infrequent 1000 year events but consider the possibility.
The inability to provide cooling because of too much pressure for a low head high volumetric flow rate source will damage even more fuel. Out first job in design and operations is to contain the fission products in the fuel to the maximum extent possible.
So what is the most important thing in achieving this means? Cooling. NRTM-20 has 10 principles for combating a reactor accident. Terminating fission is first followed by keep the core covered in close succession. If you have a large break LOCA there is a significant back pressure that develops. Large PWR containments are designed for this with a cap at around 12 psig. Ok, but now what. There is still a heat source in the bottom of the containment. If like in Fukishima we are unable to provide cooling for the contentment we risk a containment rupture. We observed three such events in Japan. AP-1000 manages this by providing steam suppression through containment spray, and natural convection on the exterior of the containment. Great Grand wonderful. We demonstrate that we can learn with time.
The decision to build nuke plants is based off of money that costs around 10% interest. This is not cheap. How much capital savings could we observe if we used smaller containments because they were vented. By the way you can do maintenance in a tight space. Just that the design has to be well thought out as to what will break and what needs to be inspected and how that is supposed to happen. Trust me it is not impossible.
If the containment was vented it would allow faster and easier core cooling. There would be no pressure buildup in the containment in a large break LOCA. The reactor would effectively depressurize itself venting mostly N-16 and crud. The crud as was observed in TMI mostly spread on the cool components and not in a direct water vapor.
From the time that core damage occurs once the active fuel height is uncovered is only a mater of minutes. Thus a low head injection (or even gravity feed) could rapidly introduce water directly to the core.
That is a large break LOCA. So far the releases are greatly minimized and the containment is fully intact allowing the casualty responders to effectively combat the event. They can then once they have achieved cold iron and a stable UHS isolate the containment. Thus a catastrophic casualty is brought completely under control in less than a day with little to no action on the part of the operators. Oh I nearly forgot about hydrogen. Hydrogen needs oxygen to be explosive. If you fill a small space with a lot of steam the steam will mix with the air. As it is a vented space the steam air mixture will leave. We ran casualty scenarios like this on the ship for a steam line rupture. We had to wear breathing protection until we could get enough oxygen back in the space. Well a vented containment becomes a massive steam jet air ejector. Thus even if you have a massive zirconium oxidation there is no oxygen in the air to cause an explosion.
We can use the collapse of steam to our advantage. If the containment is vented into a big tank of water as the steam in the containment condenses the vacuum being drawn would draw water back into the containment. Thus we are using a push pull effect to help get more water into the containment.
Lets explore this big tank idea. If there is a big tank of water, we have a fission product sponge. Water loves Iodine and Cesium. Thus venting the containment into this big tank of water we contain the two main fission products of concern. The others are noble gases that rapidly dissipate and pose little risk to people.
So I must say it the Kool-Aide that Brother Rod is serving tastes pretty darned good. Which design is safer, simpler, and cheaper, with less maintenance costs? What is the risk to the people that we are sworn to protect?
Smaller containment structures are easier to design against large plane impacts. The risk to a reactor is not the aircraft impact to the containment structure it is the impact to the auxiliary building, where all those pumps and heat exchangers are. Blow up an Aux building on a twin unit facility and watch two reactors with isolated containments go pop.
Yes, I agree with this philosophy. Using simple things like a below grade tank or pool of water is a great way to improve core and containment coolability in any beyond design basis accident.
I’ve also suggested to add a simple standpipe in the containment, in the shape of a U that is filled with water. One end sticks into the contaiment, the other could stick into the water tank. This is the passive containment venting system. If the containment is pressurized the water in the tube pushes down, until it reaches the bottom and then the water lock breaks, letting overpressure out towards the tank of water the other side of the tube. The AP1000 could easily adopt such a simple standpipe. The problem is that the regulators will delay for decades even for minor changes.
The problem is not safety requirements, its the darned bureaucracy that is clearly bent on delaying and complexing the process indefinately. This has hampered even the simplest of innovation and is why we can’t build any modern passively safe nuclear power plants. It is why the Chinese are not only eating our lunch, they’ll have finished dinner before the USA even decides to get out of bed…
Son, Cal, can I call you that since I completed my time as a navy nuke officer and had earned an SRO certification and completed a BWR startup before you were born?
If you have a model that shows venting a large break LOCA does not exceed offsite dose limits, you might change my mind about venting.
I was a certified expert in BWS including ECCS and decay heat removal including experience at all three GE containment designs.
Let me correct Cal’s first miscue. Our first job is to protect life, our second is to protect the environment, and finally we have the responsibility of protecting the assets that provide the public service of making electricity.
To understand containment design you have to look at the full range of events and the sequence of those events not just one event like in Japan. This leads to Cal’s second miscue.
During a large break LOCA, the RCS blows down rapidly while containment pressure increases rapidly. Low pressure ECCS pumps must have provisions to prevent them from going into run out and overloading the EDG. This all occurs in less than 10 minutes before people can be evacuated.
Now do you understand why we do not start with vented containment on large commercial reactors?
Third miscue is not understanding that the abnormal event in Japan was a Loss of Offsite Power (LOOP). Nuke plants are designed to get to cold shut down for this event. This event was followed by a beyond design basis event called a station black out (SBO).
Removing decay heat from core and containment is a long term issue. We have time to evacuate as a precaution. I suspect the AP-1000 like all new designs provide more time for operators to recover from the unexpected.
I have seen one new design where the diesels are not safety related but they still have then for asset protection. In Japan the assets were destroyed.
Not so much a miscue as a common belief of those from naval reactors with no stationary power plant experience. What part of bigger do you not understand? A 33% increase in power only requires a 10% containment size.
Once again, I-131 is the fission product of significance because it is volatile and has an 8 day half-life. Since N-16 has a seven second half-life and is an activation product of water is impossible to get to it after a scam. We did learn from TMI that transport models for fission products were two orders of magnitude conservative.
“Thus we are using a push pull effect to help get more water into the containment.”
Hopefully Cal is not a mechanical engineer. We are looking at decay heat levels of 100 MWte dropping down to 10 MW. This is no problem until and extended loss of AC power.
We agree that there is value in having a large, spacious containment that allows plenty of room to perform maintenance. Though we can do maintenance virtually inside a bottle if necessary, that is generally not a cost effective decision. Removing interference and opening up access points is part of the reason that submarine repair work is so darned expensive.
Size alone is not the cost driver for our containment structures. The real cost driver is the need to make them virtually leak proof up to a pressure that is generally on the order of 40-60 psig (0.2 – 0.4 Mpa). In a very large structure, the wall thickness required to meet that requirement is pretty substantial. In addition, you have to consider the effect of that pressure on thousands of seals, hundreds of penetrations, and thousands of meters of insulated electrical cabling.
If spacious containments are designed so that pressure cannot build up because there is a safe path through which to vent, the initial cost of those design features can be substantially reduced AND the ongoing cost of maintaining and testing those features throughout the life of the plant can be substantially reduced.
Cal and I care deeply about the safety of the population, but we also care about the safety of the operators (containments that pop at pressure because the operators physically could not operate the backfitted “hardened vents” demonstrates that sealed containments might not be so “conservative”). I know it is terribly un-nuke of me, but I also care deeply about finding reasonable ways to reduce the initial capital cost and the continuing ownership cost of nuclear power plants.
As the young lady in the TEDx video I have posted on my site says, a nuclear reactor is just another way to boil water. Some people like to throw that line in our face because they think it demeans what we do and why we do it. What they do not realize is that boiling water is a tremendously useful thing to do. The world consumes about 3 billion tons of hydrocarbons (including coal) per year to perform that useful act. Part of the reason that the consumption rate is still so high is that design assumptions about nuclear power plants have led us to a very expensive initial hurdle and added a significant level of complexity to what is actually a very elegant way to boil water.
Fission uses very little material, it produces a tiny volume of waste, and the physics of the device makes it a natural load follower if designed for that feature from the beginning. I know that you like coal as well as nuclear, but I hope you will admit that a fission reactor is a little easier to operate than a coal furnace and it is quite a bit easier to keep it from contaminating the local environment. (Scrubbers, low NOx burners, and bag houses are not simple or low cost devices and that is even without considering the enormous cost of trying to capture and store CO2.)
Like Cal, I am a lazy guy who seeks to make it easier to provide people with abundant resources so they can make choices about how they want to use them to make the world a better place.
If you are in your 60’s you are right about your experience. I interviewed with Skip Bowman and you probably had the pleasure of Rickover. I’ll refrain from calling you Pops. I am not a ME, I am a nuclear engineer.
First, the venting is done into a tank, and the tank is vented out an effluent stack. Cs and I, our two isotopes of concern have a large affinity to water. So passing the reactor vent into a large tank will act to entrain a good amount of the fission products of concern.
Second, it takes time for the fuel to melt during a large break LOCA. The reactor has to have sufficient time to blow down. While the reactor is blowing down the core is still covered. As there is water over the core it is next to impossible to initiate major core damage unless there has been a significant reactivity transient, which are next to impossible because of the reactivity safeguards at power and a if it were to occur during startup the power history is sufficiently low to not generate decay heat.
As long as there is water over the core and the reactor is shut down, it is unlikely that the fuel will melt. The DHR immediately after shutdown is 7% of initial power but that goes away to below the point of DNB or CHF as the reactor vessel depressurizes. So the fuel is safe for the time being.
I have to reach into the way back machine, here so the time to fuel damage for an uncovered core is on the order of 1-2 minutes from the time of being uncovered. By this time the reactor would be relatively close to ambient pressure. The transport of fission products requires a differential pressure. So the differential pressure across the reactor is relatively low likely on the order of 100-200 psig. The flashing to steam of 1000 psia water to 14.7 psia with the water initially at saturation is about 37%. That 37% is a tremendous removal of heat from the LHV of water. This does two things in the large break LOCA, it removes heat and then passes steam through the break. As steam has a much lower speed of sound the critical flow that develops is at a much lower flow rate. Of course people get PhD’s or did at one point on modeling this sort of stuff. It is complex and highly dynamic with a significant number of factors.
At this point the reactor is depressurizing and the containment has not developed any major pressure. The venting of the steam has removed almost all of the oxygen from inside the containment.
The ECCS pumps have a set of valves that restrict the flow going into the reactor in order to prevent pump runout. With a loss of all power even for a protracted period of time we have with the vented containment depressurized the reactor and containment. If this were a LOCA not in a SBO the low pressure fill system would initiate flow, as would be seen in a conventional ECCS system. We have successfully depressurized everything and initiated flow without a major release of fission products. The Xe and Kr are notable exceptions as is the Ar. All of which pose very little biological risk and are rapidly dissipated into the atmosphere. The particulate fission products are contained in the water tank and vent filter. I listed N-16 because it has a 7 sec half life and is inconsequential.
If there is a SBO, the physical structures are still intact. We have the next three days to get through without power. The hydrogen that is produced is in a steam filled atmosphere and poses no explosive risk. As the steam starts to condense the pressure in the containment rapidly drops. It does not take a large vacuum to collapse a tank. At Sequoyah we managed to provide some theory to practice on that with a rad waste collection tank. This is the beauty of having the containment vented into a tank of water. Is that we use physics to suck water back into the plant. Depending on the size of the containment will determine the amount of water that can be sucked back in. So we just added 10s of cubic meters of water without even lifting a finger. Granted the fuel is a blob at this point, but if like japan they would have been able to initiate flow within the first few hours of the casualty greatly reducing the risk of losing control of the casualty.
With no pressure in the containment it is acting as a near impenetrable barrier to fission products. This will allow the operators to respond to the casualty without having to worry about fighting the plant. This will limit the overall exposure to the population and the environment and help to achieve rapid control of the plant even without electricity.
The actions for a small break LOCA involve using the high pressure injection or even the CVCS system to prevent uncovering the core proceeded by a rapid and relatively controlled depressurization of the plant, how long it takes to lower the pressure and get a high volumetric flow injection depends on how much core damage you get. This is why the small break LOCA is such a significant challenge to prevent fuel damage. Recall that we have the containment vented into a tank of water… Thus the fission products will be entrained as before.
In a steam line rupture the containment sees no pressure increase. However, an additional system (likely compressed nitrogen) would have to be used to prevent the backflow of water into the containment. What is desireable in one is not in another. By keeping the containment at a much lower pressure we limit the damage to the installed components (steam, pressure, and electrical stuff is a bad combination) So we can then bring the plant back online more quickly once we wiped up the water and replaced the broken steam generator. So we gain something additional by venting the containment.
If you can think of any other casualties that would cause a pressure transient inside the primary containment please let me know.
As for the exposures to immediately off site, the release of the noble gas fission products will lead to some fixed surface contamination Cs and Rb with relatively short half lives, minutes.
So if you held a radiac at the site boundary you would see a spike. It may even be up to 1rem/hr but it will rapidly dissipate and is of isotopes that have little to no long term impact. So what is the risk that we are exposing the population to. How many people have you seen day in day out at the plant boundary? I see deer, and that’s about it.
I ask you this question, What is the basis of your assumptions for the exposure risk to the people we are sworn to protect? I hope that you see the assumption and yes Bob, I use the word assumption of the LNT with DDREF limits what we can do. By making those assumptions what are we being conservative about? Conservatism is a choice that has to based on understanding of the risks. What risk did the operators get exposed to at Fukushima because the contaminants were not vented? What risk did we expose the civilian population to? We are a dedicated lot and short of death will not give up our duty to operate the reactors. Why push ourselves to martyrdom? What do we gain other than a quick introduction to St Pete?
For the record venting the containment throws out your thumb rule for sizing the containment structure. If this was retrofit onto one of the few ice condensed plants it would save a whole mess of problems and costs with the glycol systems which are an awful mess.
“Thus we are using a push pull effect to help get more water into the containment.”
Let me elaborate, The steam will mix with the air in the primary containment. As the pressure builds the air and steam mixture will escape through the vent tank. The fraction of air to steam will exponentially decrease inside the primary containment structure. Leaving mostly steam. As time goes on the steam will begin to condense. As it is close to atmospheric pressure already it will rapidly form a vacuum inside the containment structure. Being a competent engineer I designed the tank to be large enough to have an adequate water heal in the tank. The pressure differential between the reactor and the outside draws the water that is left in the tank back into the containment structure. This is a large fraction of the total volume of the containment. Because I am a nuclear engineer I add a whole lot of boron into this water. I now without lifting a finger or expending a single electron covered the reactor with water after a large break LOCA. It does not matter if it is a BWR or PWR physics is physics and I am lazy.
Please remind me what my miscues are again.
I had a good laugh courtesy of Dr. Allison’s website. Did he just crawl out of a cave?
I reviewed his 4 “facts” here:
I’m glad you pointed that entry out Applebaum. Unfortunately I haven’t got time tonight to shred your answers in detail, but I will tomorrow.
Just as a preview: it’s apparent you have no idea what the “healthy worker effect” is, or when it should be applied, or you do and you are lying outright.
I will start with your last point, and give you a chance to answer.
4. The mortality of UK radiation workers before age 85 from all cancers is 15-20% lower than comparable groups.(from the main article)
“This is a well-known effect in epidemiology called the “healthy worker effect”. Here’s a 1999 article which describes it, but it was known long before then. (note I replaced your link with one to the full text)
This point suggests that Dr. Allison might need remedial training in epidemiology.
In fact it is you that needs a lesson in epidemiological research.
The “healthy worker effect” is a form of selection bias that manifests itself in one of two ways: ether the screening for new employees is such that potentially vulnerable workers are not hired, or conditions are such in the workplace that there tendency for those who develop diseases to leave their employment.
Now these were indeed cryptic factors in the coal mining industry where the effect was first documented. However in the nuclear industry, records are more complete, and evidence of both sources of bias would be available if it was a factor. Such evidence simply doesn’t exist. In fact all of the studies done on nuclear workers include subjects that were no longer employed in the field.
Consequently, this factor is not present in the results of the U.K. study, and cannot be used to dismiss it.
The problem with the logical response above from both Rod and Cal is that it sounds like they spend too much time listening to anti-nukes and do not yet have enough experience with large commercial reactors. The perception is that it is too hard, too complicated, and too expensive.
That is just not true; I have 104 nuke plants in the US providing the evidence that it is nuclear power is the not that hard, not that complicated, and very economical. This old guy thinks making steam with a reactor is less complicated than a coal boiler and I have nuclear engineers tell me about fuel design and boiler expert tell me about boiler design.
It is true that anti-nukes can provide examples to the contrary. It is too hard for some and they failed. Putting solar panels on a house is also too hard for some judging by the number of house fires. The point here is that if you are going to do something, figure out how to do it right. Being a mechanical engineer with a flare for safety, my solar hot water system worked on natural circulation with the panels on the hill below the house. Being a nuke, I had triple redundant mixing valves to prevent scalding.
My system worked too good because if enough demand was not on the system the relief was challenged every day in the summer. An SBO would result in no power to the well and the system would boil dry. What did I learn? I will let the power company make electricity for my hot water heater. Rented a house once with a gas not water heater. I had a sever headache and red completion so I checked and it was not properly vented.
My fist commercial job was local leak rate testing for a 1200 MWe BWR under construction. It was not because I was a LLRT expert but because that was the job that had to be done the day I walked though the gate for the first time. I also help with the integrated leak rate test. I have put my hands on every containment isolation valve, penetration, and inspected the containment when pressurized.
So showing that leakage is within acceptable limits is not a big deal. Just another program.
When I was talking about size I was referring to size of the reactor. Want a reactor with a 200 more MWe increase the diameter of the vessel so it can hold 20 more or so fuel assembles. The size of the reactor vessel and RCS components only increase a smaller amount.
The pressure in the containment depends on the size of the break while the size of ECCS pumps also depend on the size of the break and the amount with the decay removal capacity being much less. I have been at all three BWR containment types which have suppression pools. BWRs are vented through a big tank. It is called a suppression pool. Do not remember what peak pressure was.
As it happens I just reviewed a document that contains data on containment pressure for a very large containment. Peak pressure is about 70 psia between ten and twenty seconds for a large break LOCA for a 4 loop PWR. Tell me again about your plan to vent? The good news is that hydrogen is below the detonation limit.
Again the reason not vent is release of fission products. during a LOCA there is a certain amount of fuel damage. The criteria are that a coolable geometry remains after blowdown. Fuel rods have internal pressure that is a result of build up of gaseous fission products. ‘Hot rod’ will experience plastic deformation during the blowdown because RCS pressure decreases while some high power rods are still hot. A certain number of rods will burst. These calculations are done by reactor engineers but referenced by my group to show that the adequate flow can be provided to remove decay to prevent core melt for long term cooling.
After a LOCA, the fuel is not safe. It is in fact destroyed as well as the plant. The public and workers are safe. The difference is evacuation is not needed until either more fuel is damaged (melted) or the containment is vented.
Enough damage is done so that you can not vent the containment during or shortly after the blowdown.
SBGT HEPA filters will remove non-noble gas fission products from the limited damage as well as direct hydrogen up the stack. This requires AC power however.
Again, look at what happens in seconds and what happens in the days after.
I am also an environment engineer so I understand the fate and transport of bad things. The USSR had reactors that could blow up and catch fire without an emergency plan. LWR with containment capture and holdup fission products long enough to evacuate if the event becomes a ‘severe accident’.
The data from Japan show that no one would have been hurt offsite confirming what I have always thought. The models are conservative. Venting containments (i.e., no containment) at the start of the accident is the approach used in the USSR.
So Cal’s theory about the mechanical integrity of fuel and heat transfer does not match actual transient analysis. The next thing Cal is missing is reactivity control. What is the boron concentration of CVCS or RHR at Sequoyah when the high pressure inject are operating in the safety injection mode? You can not allow a slug of condensate to enter the core of a PWR.
At a BWR, boron is injected by SLCS when the integrity of the fuel rods are in question.
And yes, there are other accidents such as a rod ejection. Yes it complicated but we model each event one at a time. For things that happen fast, the operator does not have to do anything for a given period of time.
“I see deer, and that’s about it.”
Look in the mirror dumbass. What do you see? It is one of those trees falls in the forest question. I do not want to work with people who think dying is okay to increase profits. During the day there might be 500 to 1000 people on site. I think working at a nuke plant is very safe. I am not worried about low doses or getting cancer. We do an excellent job of preventing fatal exposures and hydrogen explosions. Never the less, the hazards are real.
We design the systems to mitigate the hazards so that the risk is very low. What models show is that the unmitigated risks are terrible. LWR had big think containments before we had anti-nukes.
As an aside, I have been in the presence of THE admiral several times. It was more interesting than a pleasure. At our commissioning I used paper clips instead of gold buttons. I suspect a man who been an officer longer than I had been alive could figure it out but rather was playing a game to see how high others would jump.
The navy was different and we approached risk differently. I was on warship with an aluminum superstructure and propulsion system that did not care about weight. Starting with our friends, things that catch aluminum on fire include the USS Kennedy and French missiles. Trial by fire, the sequel.
So this Wade Allison recommends 1.2 Sieverts per year?
And all of you here agree with that number with your apparent knowledge?
did he walk around the reactors without protection to show the world what he believes?
I lost my mother to cancer recently and what he says about radiation therapy is a load of crock. With chemo you cant just give a total dose either, not just because it would kill immediately, but because the body has to deal with the derbies of dead tumor tissue in a process called lysis. go too fast and it will kill too.
Both radiation therapy and Chemotherapy are terrible processes to witness, and it is not uncommon for those to be the actual cause of death.
Just more garbage on the heap.
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