# Japan's nuclear power plants **URL:** \ **Category:** Factual Questions\ **Created:** [March 12, 2011, 5:49am UTC](https://boards.straightdope.com/t/japans-nuclear-power-plants/574382 "2011-03-12T05:49:04Z")\ **Posts on this page:** 8\ **Page:** 6
**Author:** ![Hyperelastic](https://avatars.discourse-cdn.com/v4/letter/h/a3d4f5/32.png) [@Hyperelastic](https://boards.straightdope.com/u/Hyperelastic)\ **Post date:** [March 16, 2011, 5:10pm UTC](https://boards.straightdope.com/t/japans-nuclear-power-plants/574382/101 "2011-03-16T17:10:32Z")
> [@Sailboat](#): > > The short layman’s version: > > [ul] > [li]Harm to health is dependent on exposure (linear…more=bad, less=less bad)[/li][li]There is no safe minimum exposure (threshold)[/li][/ul] I would echo your criticism of the NAS’s use of the word “safe,” which is a relative and not absolute term. Even in identical circumstances, safety is a judgment that varies from person to person. Safety must also take the whole situation into consideration. It is not safe to run into a burning building to get your coat, but it can be safe (i.e. likely to result in the least total injury) to run into a burning building to wake a sleeping person. Saying there is no safe level implies that total avoidance of radiation can be achieved safely, which it can’t. They should state the risk as relative to the risk of a commercial airline flight, or the risk of smoking a pack of cigarettes, or something else people can relate to. It would be very helpful to know the expected rate of cooldown of the reactors and the spent fuel pools under different assumptions (normal circulation, seawater cooling, no cooling, etc.) But I am afraid there are no reporters who would even think to ask such a question, and if they did, they probably wouldn’t like the answer, which is that this, the greatest news-generating event since 9/11, has a predictable end point. I also would like a bit more perspective applied to the nuclear emergency. Even under a worst-case scenario, it is a tiny fraction of the total danger surrounding this catastrophe. Yet it has dominated the headlines for days. ---
**Author:** ![cckerberos](https://avatars.discourse-cdn.com/v4/letter/c/f0a364/32.png) [@cckerberos](https://boards.straightdope.com/u/cckerberos)\ **Post date:** [March 16, 2011, 5:14pm UTC](https://boards.straightdope.com/t/japans-nuclear-power-plants/574382/102 "2011-03-16T17:14:27Z")
> [@Sailboat](#): > > Secondly, while it is reasonable for various authorities and news sources to characterize the harm from low levels as “negligible,” minuscule, or otherwise of little account, it’s somewhat disingenuous of them to characterize the situation as having “safe levels” as if there’s some line you can stay under and be completely confident. There’s randomness involved and there’s a theoretical chance from any sort of exposure. Honestly, given the way some people out there are jumping on any excuse to succumb to panic, I don’t mind the press dumbing down this point. Fact is, there is a certain level of radiation under which no harm is scientifically verifiable. I’m okay with that being characterized as safe in this context. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [March 16, 2011, 7:24pm UTC](https://boards.straightdope.com/t/japans-nuclear-power-plants/574382/103 "2011-03-16T19:24:00Z")
radio news stated that the containment of reactor 3 may be damaged. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [March 16, 2011, 10:43pm UTC](https://boards.straightdope.com/t/japans-nuclear-power-plants/574382/104 "2011-03-16T22:43:02Z")
the storage pool at reactor 4 may have gone fully or partially dry. ---
**Author:** ![Gray\_Ghost](https://avatars.discourse-cdn.com/v4/letter/g/c0e974/32.png) [@Gray\_Ghost](https://boards.straightdope.com/u/Gray_Ghost)\ **Post date:** [March 16, 2011, 11:15pm UTC](https://boards.straightdope.com/t/japans-nuclear-power-plants/574382/105 "2011-03-16T23:15:39Z")
Cites are always nice for this sort of thing. Accordingly,[from CNN’s latest update](http://www.cnn.com/2011/WORLD/asiapcf/03/16/japan.nuclear.reactors/index.html?hpt=T1), the Chairman of the U.S. Nuclear Regulatory Commission, Gregory Jaczko, testified before a U.S. House of Representatives subcommittee the following: > [@](#): > > “What we believe at this time is that there has been a hydrogen explosion in this unit due to an uncovering of the fuel in the fuel pool,” Gregory Jaczko told a House energy and commerce subcommittee hearing. “We believe that **secondary containment has been destroyed and there is no water in the [Reactor 4] spent fuel pool,** [Emphasis added] and we believe that radiation levels are extremely high, which could possibly impact the ability to take corrective measures.” [TEPCO](http://www.tepco.co.jp/en/index-e.html) hasn’t said anything one way or the other concerning the comments that the SFP has no water remaining. I have read, but cannot find the cite, that TEPCO is disputing the NRC’s version of what’s going on, denying the NRC Chairman’s claim that there is no water within the SFP. Again, this is an ongoing crisis; accounts are going to be contradictory at times. [The NRC has advised Americans](http://nrc.gov/reading-rm/doc-collections/news/2011/11-050.pdf) to evacuate to a 50 mile distance from the plant. They stress, however, that: > [@](#): > > All the available information continues to indicate Hawaii, Alaska, the U.S. Territories and the U.S. West Coast are not expected to experience any harmful levels of radioactivity. I’d like to re-stress that for the exposed rods within Reactor 4’s SFP to pose a significant danger to people outside of the plant vicinity, the fuel bundles’ cladding would probably need to actually ignite. I do not know whether sufficient amounts of gaseous/finely divided solid radioactive materials exist within the cladding to endanger significant numbers of people outside of the plant, if the cladding were only to rupture extensively, and not actually ignite. For reasons already stated by others within the multitude of threads on the Dope and elsewhere, ignition will be **very unlikely**. Again, very unlikely. The NUREG I cited earlier has their guesses as to the probabilities, if you’re curious. Merely uncovering those fuel rods will not cause their ignition immediately all by itself. That said, if the pool(s) is/are dry, they really need to re-cover those fuel rod bundles with water as soon as possible, if only to help shield nearby workers from the radiation emitted from intact spent fuel bundles. And I’m sure that they are sparing no effort to do so, if indeed the NRC Chairman is correct with his statements. ---
**Author:** ![minor7flat5](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/minor7flat5/32/258_2.png) [@minor7flat5](https://boards.straightdope.com/u/minor7flat5)\ **Post date:** [March 17, 2011, 12:48am UTC](https://boards.straightdope.com/t/japans-nuclear-power-plants/574382/106 "2011-03-17T00:48:06Z")
> [@Sailboat](#): > > When reading press releases that imply there is some “safe” level of radiation exposure, or some level that is too low to cause damage, it’s worth noting that the National Academies of Science committee took the view that there is no such thing, at least not _per se_. > … > The short layman’s version: > > [ul] > [li]Harm to health is dependent on exposure (linear…more=bad, less=less bad)[/li][li]There is no safe minimum exposure (threshold)[/li][/ul] > … > The takeaway: radiation levels can be low enough not to worry about, but it irritates me when it’s presented like some bad SF movie where you can stand in the radiation for 29 seconds and be safe if 30 seconds is the “lethal dose.” And that’s what the Navy taught us. (Former Navy radiation tech here) There is no “safe” level. But they have to draw a line somewhere. As **robby** indicated, the civilian world is limited to 5 rem/year and 3 rem/quarter, while the Navy took the much more conservative route of dropping those limits down to one tenth: 500 mrem/year and 300 mrem/quarter. There are all kinds of issues that complicate things. Here’s a few: [ul][li]It is not unusual to receive a few mrem/month from natural sources such as the sun and radon emitters (paint, masonry, pipe lagging). The Navy measures this and subtracts it from the dosimetry reading, as if natural radiation is somehow harmless.[_]The limits we speak of normally are “whole body” dose limits. When dealing with point sources of high radioactivity, it is quite possible to have much higher exposure levels to certain body parts, such as one’s fingers.[_]The health issues don’t stop with gamma radiation—serious health problems can result from radioactive contamination (radioactive particles that come in contact with the human body)[/ul][/li]I remember reading a case study of one fellow who found a [Co-60 radiography source](http://www.orau.org/ptp/collection/Sources/radiographyunk.htm) on the ground somewhere and he put it in his pocket. In the article they showed a diagram of his body with what looked like lines from a contour map showing the different exposure levels he received. Not surprisingly, he received absolutely massive doses to his thighs and his Johnson, with much less exposure to his lower legs and other parts of his body. He lived to tell the tale, but lost everything from the waist down. The amazing thing is, his body parts received what would have been guaranteed lethal doses had they been whole body exposure: he would have dropped in his tracks. For example, his manhood received a 3000 rem dose (not mrem). Fortunately, this was not a whole body dose. And about that contamination: Our clothing and dead skin cells do a peachy job of stopping such nastinesses as alpha particles (a helium nucleus) and beta particles (electrons). Those alpha particles are like big giant bowling balls and do substantial damage, but don’t penetrate far; however, if the alpha emitter is ingested or gets into an open wound, the alpha particles don’t have to travel far at all to cause mayhem at a cellular level. Any kind of ingestion is bad news. ---
**Author:** ![Gray\_Ghost](https://avatars.discourse-cdn.com/v4/letter/g/c0e974/32.png) [@Gray\_Ghost](https://boards.straightdope.com/u/Gray_Ghost)\ **Post date:** [March 17, 2011, 1:12am UTC](https://boards.straightdope.com/t/japans-nuclear-power-plants/574382/107 "2011-03-17T01:12:12Z")
[quote=“minor7flat5, post:106, topic:574382”] There are all kinds of issues that complicate things. Here’s a few: [ul][li][_]The limits we speak of normally are “whole body” dose limits. When dealing with point sources of high radioactivity, it is quite possible to have much higher exposure levels to certain body parts, such as one’s fingers.[_][/ul][/li][/QUOTE] In a related vein, see [Anatoli Bugorski.](http://en.wikipedia.org/wiki/Anatoli_Bugorski) [In 1978, he leaned into a beam of energetic protons from a particle accelerator.](http://www.boingboing.net/2011/02/22/what-happens-when-yo-6.html) [He received a dose in the vicinity of 200,000 rads to his head.](http://www.wired.com/wired/archive/5.12/science.html) Not a typo. Not sure what quality factor you’d have to use to convert that to Rem, but he received one hell of a dose, anyway you look at it. That the beam was finely collimated I’m sure had a lot to do with his survival; what the beam touched, it nuked, but it didn’t seem to harm much else around the beam path. Wouldn’t want to have to insure him against cancer though… ---
**Author:** ![Gray\_Ghost](https://avatars.discourse-cdn.com/v4/letter/g/c0e974/32.png) [@Gray\_Ghost](https://boards.straightdope.com/u/Gray_Ghost)\ **Post date:** [March 17, 2011, 2:13am UTC](https://boards.straightdope.com/t/japans-nuclear-power-plants/574382/108 "2011-03-17T02:13:37Z")
Last post for awhile, but it looks like TEPCO [might be worried](http://content.usatoday.com/communities/ondeadline/post/2011/03/new-fire-reported-at-fukushima-reactor-no-4/1) [about a criticality accident](http://www.guardian.co.uk/world/2011/mar/16/fukushima-workers-evacuate-radiation-spikes) [within the SFP](http://www.bbc.co.uk/news/science-environment-12762608). > [@](#): > > [From USA Today link] There’s growing concern that the spent fuel rods at the No. 4 reactor at the Daiichi plant could reach “criticality” again and restart a nuclear chain reaction. Tokyo Electric Power Co. now says it might use helicopers to drop boric acid on the exposed fuel rods outside the plant reactor, which was offline before Friday’s earthquake and tsunami. During normal operations, boron rods are used to control the nuclear reactions inside a reactor. > > ‘‘The possibility of recriticality is not zero,’’ TEPCO said in announcing steps to counter a possible fall in water levels in the pool storing the rods. How is this possible? Perhaps the neutron absorbing materials—boron or cadmium sheets—were dislodged within the SFP by the earthquake or the possible loss of water. I didn’t think you needed such things,[but if you have the pool stuffed full of fuel elements](http://www.reuters.com/article/2011/03/15/us-chernobyl-clean-up-expert-slams-japan-idUSTRE72E7AL20110315), they may be needed to ensure against an inadvertent formation of a critical mass. If there is no water within the pool, the fuel assemblies are much closer to each other than they should be—or damaged, and the fuel allowed to accumulate closer than it should, and the neutron absorbant is not where it should be: since water is a moderator of thermal neutrons, _adding_ water may enhance the chances for a criticality accident. What a mess. [Previous page](https://boards.straightdope.com/t/japans-nuclear-power-plants/574382.md?page=5)