Reading this page on Integral Fast Reactors (IFR) they look to my admittedly amateur eye as the best bet for nuclear energy production available. That site says 99.5% of the nuclear fuel put into the reactor is eventually used compared with 1% in Light Water Reactors. The chances for plutonium being nabbed from such a place to be used for a nuclear weapon seem near impossible. By design the plutonium is mixed with other fuels such that anyone walking off with it would need to have the waste undergo istopic separation…no simple matter especially with stuff as nasty as this.
Yes, this material would be suitable for a dirty bomb but then many things are suitable for a dirty bomb. This link describes a visit to a FBR and shows how difficult it would be to obtain anyway. From that link:
Interestingly the link above describes a test where the reactor was going full blast and the pumps were intentionally shut down. The reactor shut itself off (passively safe).
As nuclear fission reactor designs go the IFR seems about as clean and safe as you are likely to get. It may not money out on the economics yet but that is a different issue entirely.
Hey, same for me! And I am a pretty woman. Thus, I decided I’d better not stick around in the nuclear navy where my oogling had to be much too surreptitious for my tastes I would hate to screw up my newfound freedom with a poorly edited post.
I’m sorry for the hijack, but if you’re on this topic you really need to hear about this. I was standing watch on my carrier’s bridge one day when I heard the new helmsman going on and on to the cute leehelmsman about how he liked to do science and math research and he was currently looking into the nuances of the quadratic equation. I had to turn around to see who could be such an idiot, and there he was, the Nuclear Boyscout himself. Recognized his name from the Harper’s article on the subject.
Now, I have mixed feelings as it is about judges telling young criminals “you can go into the military, or you can go to jail.” I had one division that was about 10% “reformers,” and while I really wanted to help these young men, most of them didn’t want to be helped. In any case, what idiot would send THIS KID to a nuclear aircraft carrier?! It’s like sending a convicted child molester to do public service in a pediatric hospital. Worse yet, I went and talked to the guy in charge of giving access to the power plants, and it turned out this kid was working on becoming an interior communications electrician and had just applied to get his dosimeter so he could get into the reactor spaces. You can bet I put the crush on that very quickly!
Again, I’m sorry for the hijack. I just had to tell you how individuals can screw up this government security thing, even though the whole system is more than a bit overblown.
It is partly for space reasons - I’m 5’4" and was about 125 lbs when I was training on a sub, and it was cramped in there for me! I can’t imagine getting cameramen into some of those spaces, let alone some guy with a boom mike etc. It’s not like you could clear out the operators to get the camera crew in - they have to be in there 24-7.
I’ll second OtakuLoki’s answer on this one. It’s not that the subject is special, it’s that I and many like me want to keep our tender hides out of Leavenworth.
As to why the government insists on that, honestly, it really bothers me. I could understand the secrecy up front when nobody knew anything about design, but I’d imagine the cat is pretty well out of the bag by now. The artists formerly known as Soviets, especially, probably know as much about our plants as we do. I guess you could argue in favor of keeping the plans secret since damaging a plant would be a lot easier if you knew the exact layout (ie where to strike the hull), what materials were used, and so on.
Bottom line, though, I think the government’s effort to keep things to ourselves has resulted in a grossly overblown mistrust of nuclear power. It does have huge problems, the waste thing in particular, but I wish we could have a dialogue (as we are in this thread) about the actual problems, rather than the imagined B-movie radiation monster problems. As much as they frustrate me, it’s hard to blame the environmentalists in their extremism when they don’t have much of a hope of understanding what the real issues are. Then again, if they had a thorough grasp of 8th grade science it would help, but that’s a subject for another thread, I guess.
You are quite welcome - thanks for bringing up such thoughtful questions. I’m learning so much with this thread.
I read an article about him after reading about him in Cecil’s column about thoriated gas lantern mantles. (Sorry, I don’t have the link). IIRC, the writer said that he wasn’t allowed to work on reactors because he had already exceeded his allowable lifetime limit of radiation exposure. I also thought that he was dying or was dead. Are you sure it was the same guy?
Not to defend the guy’s actions, but he wasn’t trying to make a nuclear bomb or anything. He was doing unlicensed breeder reactor experiments for his Eagle Scout merit badge. It is hardly a case of sending the fox to guard the henhouse.
Here’s the Wikipedia entry on David Hahn. The article claims that “he was kept away from the nuclear reactors, largely for his own safety, as he had reached the point that further exposure would result in illness,” which is somewhat improbable; while a high level of short-term radiation can cause radiation sickness, and long-term exposure to slightly elevated levels correlates with a greater incidence of many carcinomas, radiation exposure isn’t cummulative in the sense that residual poisons are.
Fair enough - it’s just that in order to do what he did, he must have known a thing or two about fissionable materials. So, to then proceed to amass them in his backyard shed and intentionally concentrate them without some serious precautions (if you read the Harper’s article you’ll get an idea of the trash-bag type “containments” he was using) indicates to me a shocking lack of critical connections somewhere between the ears, or at least gross disregard for the safety of himself and others. Whatever the issue, I wouldn’t want him anywhere near the controls of something horribly dangerous that has tempted his intense (is that a strong enough word?) curiosity in the past. I also wouldn’t let a guy load munitions if he’d been arrested for blowing things up with home-made pipe bombs. I’m completely prepared to admit that I may be overreacting. Abundant caution is good in a nuclear engineer.
Yep, I’m positive it was the same guy. He fessed up to it with some embarrassment when he was brought in to discuss his radiation badge application.
Yeah, it’s a load of hooey, for the reasons you named. According to him, he asked to become a Nuke (and I’m guessing he was smart enough) but because of his earlier gross errors in judgement his request was declined for security reasons, not because of radiation exposure. He had also been ordered never to seek a job that involved access to information on the reactors or reactor spaces, which is why he got in trouble with us. In any case, non-occupational exposures aren’t covered by OSHA, and therefore aren’t included in the Navy regulations based on OSHA standards. It sounds like a good story for him to tell to save face, though. If I were a reporter I’d buy it, and I couldn’t even really blame young Mr. Hahn for telling it.
Spacekat, cool to see yet another nuc (or former nuc) on the Dope. I do hope you’ll stick around once your guest period is over.
<hijack>May I ask what your rate was, and where your training was? In part I’m confused about the comment about sub plants being so tight you couldn’t fit a TV camera in 'em. Of course my whole career was on surface plants, really. Things were tight, and I’d seen one guy lay himself out flat trying to respond to a drill situation and forgetting about a low overhead. But not that tight. (S3G was a plant for a sub, but it had things like steam driven pumps, a DFT, and other specifically ‘surface’ features that leave me wondering just how representative of sub plants it really was.)
</hijack>
While I see your point to wondering about the concerns the gov’t has about keeping us quiet about nuclear plants, I am not quite as willing as you to see them go away. I still remember the crack about nucs being “all brains and no common sense” and can easily imagine situations where someone with more mouth than brain would talk about things without considering consequences. And, I’ll admit, I’m skeptical of the public’s desire to be educated about the realities of nuclear power.
Whack-a-Mole, I really don’t know what kind of refuelling schedule a PBMR reactor would need. I’m having trouble imagining a reactor that couldn’t be designed to get around that. I’m sure that it would be more difficult to engineer, but that’s a world of difference from saying it would be impossible.
Likewise, and thanks! Yeah, I’m a medical student now but I’m going to see if I can scrape together some scarce pocket money and stick around here. I have learned so many cool things in the past couple days, and have laughed my ass off which is even better.
I was one of the first women trained as officers in the program. Believe it or not I was recruited as a submariner, but Congress/JCsofT did another about face so I ended up in surface, which was fine. In any case, I did prototype on those old Lafayette class in Charleston and have been a guest on several active subs. Boomers are a little bigger, but I’m telling you, even modern fast attacks are TIGHT. The Lafayettes were the worst, though - anyone bigger than me (80% of the adult US poplulation) would be squashed, and in many places even two of the smallest people couldn’t pass each other in the engineroom. Never bothered me, but the poor guys who got bombarded with sexual harassment training before I showed up were nervous as hell until they realized I was on their side and would never do them in. No comparison at all to suface plants, even on the Enterprise where things are packed pretty tight due to vintage/cramming in 8 of those puppies. When I first saw a surface plant I thought it looked like a good place to play football.
I definitely see your points about the secrecy - I keep trying to be optimistic about people, even though it nearly always gets me kicked in the teeth.
Cool story. Well, to get back on track, I’d like to know what the nuclear engineers around here think of PBMRs. The Chinese are apparently betting on them to provide the electricity they are going to need. What are the gotchas in building one. Do they need a containment dome? What can and/or should be done with spent pebbles? If we committed to building one today, how long would it take to come online? How valid are the objections? Are they competitive?
Now we’re really getting into rarified territory with these questions. I honestly can’t tell you what the gotchas would be with a PBMR. That is the sort of thing I was talking about where my knowledge is unable to offer even a guess about. Likewise that’s the same answer I’ll give you about time to having a plant in operation.
As for a containment dome - that’s a bit easier. If we’re talking about helium as the heat transfer medium, I don’t think there’s any point to a containment dome. Helium can’t carry entrained contaminants, and doesn’t activate to any signifigant degree. The purpose of a containment dome around PWR and BWRs isn’t to stop a Chernobyl type release, but to prevent release of contaminated steam from a cooling line rupture. This isn’t to say that containment domes won’t be built around PBMRs. Just that I don’t think one would be necessary.
As for the objections - we’re starting to get to the point where people have to measure relative risks. First off, I don’t believe that at this point it is fair to compare the costs, and risks of nuclear power to anything but coal power. That may change in the future. If we get a breakthrough in solar power efficiency, for example my current judgement of relative risks is bound to go out the window.
So, the costs for coal power, in my mind, have to include the clean up costs for fly ash, the costs of coal mining, including how regular casualties are. And not just the large-scale disasters like the most recent coal mine accident here in the US, but the regular deaths from small rocks falling from the overhead in the mine. And all the other health concerns for coal mining and burning. When all that is factored in, I think PWRs are better. And since PBMRs remove some of the bigger headaches with operating a PWR, I’m even more inclined to see them built.
But I have to point out, I can see the viewpoints of some of those people who disagree with me. There are a number of rational people who disagree with me, and who have real understanding behind their views. The original topic of this thread is a case in point - the reprocessing of spent reactor fuel. It’s not an all or nothing argument. I just think that many people don’t give it enough thought.
From what I understand, I agree with you that containment domes wouldn’t be necessary to prevent coolant release but it seems like a structure would be necessary to protect the reactors from things like planes flying into them. Would it release a large amount of radioactive smoke if a plane destroyed the fire supression equipment and set the pebbles on fire? One of the hopes of PBMR advocates is that the reactor vessels can be commoditized and added to an existing plant as demand increases. Wouldn’t a containment dome throw a monkeywrench into that?
I was after a comparison between conventional reactors (the latest designs) and PBMRs. I originally wrote this post to Cecil and then found that the bigger objection to reprocessing is that its cheaper to use new fuel. I also found out that easily accessible uranium sources are likely to peak in the next few decades. I was wondering if it was really necessary to permanently sequester spent fuel or if that could be stockpiled for future reprocessing, stuck in RTGs and attached to the grid or some other “waste not, want not” approach.
I also want to know how to use waste environmental heat to power my a/c, but that’s another thread.
A Scientific American from last fall (probably Oct. or Nov.) had an article on the wonders of fast breeder reactors. Here are the salient points as I recall them.
Instead of using up about 4% of the available nuclear energy from the fuel, it would use 95%.
Instead of leaving radioactive waste that has half lives measured in the tens or thousands of years for the most dangerous components, the waste would be fircely radioactive at first, but decay relatively quickly so that if would not be a disaster if surveillance were abandoned in a few hundred years.
It could use reprocessed fuel left over from current reactors as its own fuel, thus solving that problem too. Of course, the problem of moving it there remains, but any means of waste disposal has that problem.
It would not have to reporcess its own fuel; it would just continue to “burn” it until not enough nuclear energy remained to be useful.
On the other side is the fact that we have little or no experience with this sort of reactor.
Aside from this Sci-Am article, I have seen no public discussion of these reactors and they do not seem to be on the table. Assuming the article is correct (and I am not in any position to know about that), this would seem to be something well worth investigating.
I would hate to screw up my newfound freedom with a poorly edited post.