Posted on 07/09/2002 4:09:32 PM PDT by corlorde
The U.S. Senate gave final congressional approval on Tuesday to President Bush's decision to bury deadly nuclear waste from across the nation in Nevada's Yucca Mountain, setting aside the state's safety concerns that will be heard in federal court challenges.
Senators approved a resolution -- previously passed by the House of Representatives -- to override Nevada's veto of the administration's plan to put the country's first permanent nuclear waste repository in the Nevada desert, 90 miles northwest of Las Vegas. The action effectively clears the way for the U.S. Energy Department to apply to the Nuclear Regulatory Commission to license the $58 billion project, scheduled to open in 2010 and hold 77,000 tons of radioactive material.
The state of Nevada has already filed suits in federal court to try to stop it, and will take its case to the NRC that despite administration claims to the contrary, Yucca Mountain is an unsafe site for a nuclear dump.
Factually incorrect. This postulated scenario is not supported by the laws of physics. Dispersion of material driven by an external force (e.g., a missile explosion) results in very localized contamination. Widespread dispersion is always associated with release of significant amounts of internally-stored energy. Decayed fuel (the kind that will be shipped) has greatly reduced stored energy. It will not become supercritical and even if it did it would not result in a nuclear explsoion (you need significant compression of highly-enriched fissile materials for that, which fuel is not). Nor is significant vaporization (another requirement for widespread dispersion) likely given the physics of the explosive process driving the dispersion, and the material properties of the fuel (it doesn't pulverize or vaporize very readily).
2) even without a terrorist threat, trains derail and trucks crash all the time...
Nuclear materials have been shipped in this country for over a half a century, involving tens of thousands of shipments. During this time, a total of eight transportation accidents have occurred involving nuclear materials. Of these, none of them resulted in the release of radioactive materials, and none of them resulted in fatalities or injuries to the public.
and 3) even after the site is at full capacity, the waste left over will still be about the same as today.
That is an insufficient argument against the proposition that the inventory of used fuel on hand should not be stored in a central, stable, isolated repository. The fact that the waste stream will not be immediately reduced to zero is irrelevant and does not invalidate the many sound technical, economic, and national security arguments that support the Yucca Mountain plan.
IMO, this whole statement is yet another reason why commercial reprocessing should be resurrected in this country. What better way to reduce plutonium inventory than to fission it away as fuel in a reactor?
But, that aside, I cannot see this as a very great threat. This is because you still need significant reprocessing capability to extract the plutonium from the fuel matrix. That can be done (we used to do something like it at the SRP and of course Hanford) and if someone in the future is smart enough to have this capability they would probably be better off getting their plutonium an easier way, and that is by breeding it in a production reactor, just like we did in the Manhatten Project.
Run the numbers yourself to check the power (i.e., activity) in used fuel as a function of decay time. A good statistical approximation is the Way-Wigner relationship [1]. If that doesn't appeal to you, you might try the empirical fit developed by Untermyer and Weills [2] which uses experimental data. Its a little messy, but spreadsheet programs can handle it.
ref.:
[1] Way, K., and E. P. Wigner, Physical Review 70:1318 (1948)
[2] Untermyer, S. and J. T. Weills, "Heat Generated in Irradiated Uranium", ANL-4790, 2/25/52.
Better one area for the future Indiana Jones to find than hundreds of contaminated sites around the country.
But you still need to do separation, and doing transuranic/actinide chemistry is not the kind of thing you do in your basement (I know because I have worked on it, and not in my basement). Anyone who is smart enough to do that will likely be smart enough to cobble together a production reactor and irradiate targets of uranium specifically designed to facilitate the production and subsequent extraction of bred plutonium, rather than digging up Yucca Mountain and playing with material that never was really optimized for production and extraction of weapons-grade material. You can live with the need to do hot chemistry on irradiated targets. Hot cell technology is no more of a problem to develop than the extraction process. An inexperienced national program can do it.
Actually, you're in a lot more danger from every gasoline and propane tanker that barrels down the Interstate than from truckloads of nuclear waste.
Furthermore, a truckload of nuclear waste is the product of far more energy expended than will ever be produced by a tanker of gasoline.
I wish the waste repository had been built here in Phoenix. We have a stable nuclear site for it, and we need the jobs it would create.
The libs (except the wicked RAT Sen. Reid of NV), want to be sure the stuff is stored where only the citizens of the Red states will be irradiated when an accident happens. Far fewer conservative voters that way.
Injestion hazard? You're talking about people eating the material? That is a far-fetched scenario. If you're going to go that route, you need to account for transport through the biosphere. Any kind of reasonable malicious use scenario will involve some type of clandestine dispersion, which greatly reduces concentration. You're comparing apples to organes. Sure, a pile of spent fuel sitting there after a thousand years would be hazardous to someone walkming up to it and eating it. But any kind of dispersion means dilution and you're again talking about small concentrations.
Lets look at the specfic nuclides you mentioned. Np-237 has a physical half-life of 2.14 million years, and the estimated inventory in spent fuel circa 1994 was about 7900 Ci. For Np-237 the physical half-life is 213,000 years and the inventory about 345,000 Ci. This sounds like a lot but when you calculate the specific activities you find the forms are very dilute. Fission/activation just doesn't make that many of those nuclei. The physical half-life for Iodine-129 comes in at 15.7 million years, but if you're talking biohazard then you need to account for biological half-life. For iodine, this is age-dependent. It averages about 11 days for infants, 23 days for 5 year-olds, and 80 days for adults. So for any kind of dispersion scenario, wherein the release is of short duration, you'll have an initial organ dose that will reduce with time as the material clears the body. The biological effects for this form are driven more by biological half-life than physical half-life.
But this has nothing to do with my point, which is that spent fuel is not reactor grade plutonium. There is plutonium present but in a form that requires some reasonably complex processing and refinement. Commercial reprocessing would never have been developed and proposed by the industry if it were not possible to recover plutonium from the used fuel, but it would not be a simple step. A national program in a country with sufficient infrastructure and resources could do it, but an independent group or individual would find it a challenge.
My first point is that you cannot guarantee that the repository will be safeguarded 100, 200, 300, 500, 1000, ... years from now. We're talking time periods beyond the history of this country.
You can't guarantee anything. But you need to weigh the risks against the benefits, and IMO the benefits of using the technology outweigh the risks, even including the unlikely ones. What I can guarantee is that it will be easier to detect if there is a diversion attempt at a single, secured site than it would be if you have dozens of sites scattered around the country. Simple estimates of resource utilization and deployment will show that to be true. Providing security at Yucca Mountain presents less of a challenge than for dispersed sites.
My second point, as supported by other researchers, is that it would not be very difficult to extract weapons-usable material from a repository.
Very difficult for whom? Nothing like using undefined terms. An experienced national program? Yes, you can get plutonium and other things from the used fuel. An inexperienced national program, perhaps. An independent group with experience or no? Doubtful. A single individual? Highly unlikely if not impossible.
My third point is that the extractors could be a subnational group that could use the material for malicious purposes. It is no more far-fetched than terrorists flying jetliners into skyscrapers,
Nonsense. Thousands of jetliners are around everyday, poorly guarded even now, much less pre-Sept. 11th. You don't have used nuclear fuel rods flying around the country by the thousands every day. Now they're all at power plant sites. If Yucca Mountain goes through they'll be underground down in a thousand feet of volcanic tuff. There's no rational way you can compare the relative risks, and attempting to do so is nonsense.
But, if you think its no more far-fetched, tell you what, give it a try sometime. Go ahead and attempt an extraction operation from a spent fuel storage pool. Just make sure before you do that your affairs are in order and your loved ones are provided for.
and the consequences would be a heck of a lot worse.
Only if there were the construction of a usable nuclear weapon from the diverted material, and, again, an inexperienced national program might be able to do it if they had access to enough material and were reasonably advanced, but, again, they'd probably be better off either doing their own separations of 235U or breeding plutonium in a reactor. Dispersion weapons aren't going to cut it in terms of widespread effects.
Yeah right. I don’t get it. This from someone who blows off external exposure considerations, evidently unaware that any kind of comprehensive radiological hazard analysis will account for both external and internal exposures.
Thankfully, DOE in its design of the repository facility does not take such a cavalier and uninformed approach. External exposures have indeed been considered and incorporated in aspects of the repository siting and design. And the accepted methods of characterizing the source term and postulating reasonable exposure models are used. In fact, one of my first jobs after graduating was working with a group contracted by DOE to look as just this issue. And, perhaps surprisingly, while some of the scenarios (exposure models) might be considered implausible, they are in fact more plausible than the dispersion model you seem to be so hung up on. They have been mentioned right here on FR, in this as well as other threads related to this subject. The most likely being surface exposures immediately upon filing the repository with as fresh used fuel as possible. Yes, it’s a thousand feet down in tuff surrounded by engineered safeguards, but you’ve got gigacuries of mixed radionuclides emitting various radiations, and that merits consideration of the exposure model wherein an individual is sited on top of the mountain directly above the canisters. You’ve got direct exposures in the range of millirems per year. Not a hazard by any means, but it shows that the case has been considered.
Other models? Of course, the case wherein people are still working at the site prior to its closure. There the source term and exposure models are different, but the results are similar: no exposures above allowable occupational limits. Unauthorized intrusion after repository closure? The most likely is a deliberate attempt to recover the material for beneficial use. Imagine an energy poor future wherein knowledge of what is there at Yucca Mountain is retained, and our progeny curse our short-sightedness for burying such a valuable energy resource, and seek to correct our error by recovering it. Exposures are then possible and perhaps significant, out to a certain time. The same goes for accidental or malevolent intrusion.
There is never any threat from external exposure to radiation because at any time after the spent fuel is placed in the repository, the fuel is 1000 ft below the surface and well shielded. If you want to compare spent fuel to natural uranium, the measure of performance is the ingestion hazard index (IHI). Again see the Figure 11.31, p. 623 of Nuclear Chemical Engineering, also referenced in the pervious post. The IHI is a weighted average of the radioactivity (by isotope), normalized with respect to the maximimum allowable concentrations of these isotopes in drinking water, per federal regulations. The units for IHI are volume of water (e.g., cubic meters of water, sometimes it's normalized with respect to the metric tons of initial heavy metal in the fuel). The IHI can be interpreted physically as the volume of water required to dilute the radioactivity to a level that it could be consumed with negligible risk. The bottom line is that the IHI for unprocessed spent fuel will not drop below the IHI for natural uranium until after about 1 million years of radioactive decay. Visualize two repositories, one containing unprocessed spent fuel and the other containing an amount of natural uranium ore that was needed to make the fuel. Neither repository will pose an external radiation hazard. However, the repository containing unprocessed spent fuel will remain more hazardous (with respect to radioactivity escaping the repository and getting into the groundwater and bioshpere) than the repository containing the natural uranium for about 1 million years.
I’m not questioning your sources on the IHI issue, just your application of it in this context, which seems to be more of a scare tactic than a reasonable risk analysis. You appear to be narrowly focused on the dispersion issue and giving it more weight than it really deserves in reality.
Going around throwing out the IHI for something without specifying a reasonable case under which the IHI becomes a concern is an incomplete picture. I’d guess that almost anything you have around has an IHI or something analogous to it, some of it probably pretty high. The gasoline in your car’s tank, the combustion products in your home’s furnace, the computer monitor you’re looking at now, all would pose an injestion hazard. But you don’t really worry about that because reasonable precautions are taken to preclude that. So the IHI becomes a non-issue, whatever it is.
It’s an argument in the same vein as the anti-nuke canard about plutonium. You know, the one about how “one gram of plutonium can give everyone on Earth lung cancer”. Well, my response to that is BFD. If you haven’t stated a reasonable manner in which that one gram can be distributed precisely to each person on Earth, the argument is bogus.
So lets use a variation of your argument above to visualize two cases. You’ve got two repositories sitting there, one with natural uranium and the other used fuel. You’ve sealed them up a hundred years ago. Both will have an external dose rate and an IHI. You’ve broken in and are checking things out. Which is more hazardous? The used fuel because of external exposures. Now you wait a little longer, perhaps a thousand years after sealing it up. You’re checking things over and what is happening to you? You’re getting some external exposure from the uranium, but less from the used fuel. In either case, the IHI is not the deciding factor because you’re not injesting the material. Ah, but wait, you say, don’t blow off the chance that some way could be found to disperse the material and thus effect injestion? Well, then, other considerations come into the picture. You need to postulate a dispersion mechanism, and its associated effects that may or may not make the IHI an issue. To that end…
But in reality, neither repository should pose a long-term radiological risk, provided the waste is packaged properly and corrosion, transport, and dilution mechanisms are accounted for.
You are correct. and in fact, the design accounts for them. The fission product transport rates we measured for the volcanic tuff at depth in the YM formations are measured in terms of centimeters per geologic age. How do we know that? One way is by experiment. You take a source of fission products and begin it diffusing through the material of interest. You account for different conditions, totally dry, totally saturated with water, and various points in between. You use extremely sensitive assay techniques (ICP-MS, or isotope dilution, for example) and measure the number of atoms of the material at various points along the diffusion path. Another way is looking at the geologic record. Fission product migration in natural limestone from the Gabon fossil reactors indicates very limited dispersion, even in a totally uncontained system.
Corrosion rates for canisters? You betcha those are known. One thing materials science types are good at is measuring corrosion rates. Those waste canisters might eventually fall apart in a totally saturated environment, in a time measured in hundreds of millennia.
A possible exception is the flooded repository scenario I mentioned previously, which would enhance corrosion and transport to the biosphere. The DOE has refused to publish results for this scenario (maybe the results didn't look so good?), which could pose a problem when trying to get the repository licensed by the NRC.
This issue was looked at in some of the early siting studies dating back to when the politics of the disposal process dictated that two sites (east and west) be developed. The most likely means of flooding the repository, based on the accepted principle of uniformitarianism, is a gradual raising of the water table in a given area. For the case of Yucca Mountain, this means a rise of about a thousand feet. Given the nature of the strata at depth there, any kind of diastrophism that will cause this will do so over a time period on the order of tens of millions of years, long enough for even your beloved IHI to drop off significantly.
Thus, dispersion driven by a natural process would be unlikely to result in a significant biohazard. So what about unnatural processes, deliberate or accidental? Well, this overlaps some of your other points, noted below.
The real issue is do you really want to bury about 50,000 bombs-worth of weapons-usable plutonium in a repository for which you cannot guarantee safeguards for the required time periods (tens of thousands of years). Clandestine recovery of sufficient plutonium to make several weapons is not an implausible event in the not-to-distant future, several hundred years after the repository has been closed.
Chemical separation of plutonium from spent fuel is not the simplest process in the world, but there are well-established solvent extraction processes (PUREX) that become a lot easier if the spent fuel has aged a few hundred years, because the radiation barrier is greatly diminished (as shown by the decay curves you are so proud of). You can get several bombs-worth of plutonium from a single cansister, and the separations facility could be about the size of your basement. A future Tim McVeigh would not need national-scale resources to do this, nor would he need national-scale resources to retrieve a single canister from the repository. A small group could pull this off.
What you’re implying is a kind of “The End of Civilization As We Know It” scenario, a situation wherein government authority has collapsed, safeguarding of the material is not being actively done. Since you brought up the spectre of “a future Tim McVeigh”, for the purposes of this discussion, lets take that scenario and run down its implications.
First, keep in mind that McVeigh’s motives for what he did were to harass a government that he thought was or was becoming oppressive. But in the end of the world scenario you’re postulating, either Tim has been successful at doing away with that or perhaps someone else has done his work for him, so what motive would he have for digging up Yucca Mountain, setting up a PUREX extraction facility, and going through the trouble of fabricating a fission bomb? It would seem Tim would be going through a lot of trouble for nothing.
But, if you’re willing to blow off this eminently logical and practical argument which totally demolishes the pretext, lets continue to run through the scenario. Next, we have to consider a reasonable sociopolitical model that might allow us to predict the conditions of such a time of likely chaos and disorganization. More often than not, in conditions leading to the collapse of fundamental governmental authority of relatively stable political systems and institutions, there is a concurrent loss of knowledge and technical infrastructure. Thus, we have to ask ourselves, would Tim have the knowledge that Yucca Mountain was even there? Probably not. If he did, would McVeigh understand the nature and potential of what was emplaced there? Likely not. If he did, would he have the ability to extract it? Remember, we’re talking about material sealed up in man-made structures and artifacts a thousand feet down in volcanic rock. Its not the kind of thing that Tim would dig up with a pick and shovel. He’d have to have fairly sophisticated mining equipment, explosives, and a cadre of skilled and trained people around to help him. Would such be available in a new Dark Age?
But, okay, say McVeigh is able to break into the repository. He gets a few of those canisters out. If it’s a few hundred years after disposal, the external radiation hazard is diminished to the point that he doesn’t kill himself. So then what? Those canisters aren’t the kind of thing Tim is going to break open by hitting it with a rock. He tries but all he does is pulverize the rock. He swings his pickax at a canister. His pickax breaks. He tries a hack saw. The blade dulls down to a smooth strip. He tries to break one open by running his excavator over it. All he succeeds in doing is breaking the suspension of his vehicle.
No, he’ll have to have access to some fairly sophisticated cutting technology, maybe high speed water jets, e-beam or laser welder/cutters, or high temperature plasma torches. Has that technology survived the collapse of civilization? Problematic.
So, maybe somehow McVeigh and his gang can get the pellets out of the canisters. He needs access to fairly sophisticated technology to effect plutonium separation. Has the knowledge of PUREX survived the collapse of civilization? Does Tim have that knowledge himself, or can he find someone who does? Can he get the apparatus and materials necessary to get a PUREX reprocessing line going?
But, lets say, for the sake of argument, that somehow Tim pulls it off up to this point. Perhaps he even has a formula quantity of plutonium to work with. What then? Well, has the knowledge, skill, and infrastructure necessary to complete the job survived the end of the world as we know it? Remember, getting a formula quantity of material is only part of the battle. You still have to make it work. That means you need someone around who is good enough with shaped charges and explosives to produce a symmetric and focused implosion of the kind necessary to achieve a compression of a factor of about two for the fissile material assembly. While Tim has demonstrated his ability to assemble a fuel oil and fertilizer bomb, that isn’t going to cut it when it comes to making an nuclear weapon go boom. You need access to technology that is essentially a plutonium forge. Remember, if you’ve separated out enough plutonium for a formula quantity, it is radioactive. You’re going that have to fabricate the material into the appropriate metallic forms that you can machine. Has that technology survived the collapse of civilization? If you get the plutonium into suitable metallic form, do you have access to fairly sophisticated machining technology, and people who can run it? You’ll have to do precision milling and lathing in an inert atmosphere. Are there machine tools around after civilization has collapsed? You probably are not going to be successful fabricating a plutonium core using chisels and files, much less considering poisoning yourself with plutonium particulates. You also have to come up with an initiator (itself a tricky proposition) and tamper. Then you need a sophisticated electronics package to set it off. Any chance that kryton switches can be had after civilization collapses? They can be had in today’s world, but, then again, we’re not talking about today’s world here.
So, okay, then, Tim decides that maybe it isn’t worth the trouble to go boom, so he’ll go the radiological dispersion route. After all, the stuff has an IHI, right? Just spread it around the environment. Well, now we’re back into the same old arguments about the “dirty bomb” business, and having slogged through a dozen or so threads on this subject, I’m tired of demolishing yet another one. Suffice it to say that the hazards associated with a radiological dispersion weapon are greatly exaggerated in the public mind. Dispersion driven by external explosive forces is just too limited to be considered a threat to the general public at large. Sure, it will cause some local cleanup problems, but hardly the “death of billions” whining we hear all the time in these kinds of debates. And that’s not even taking credit for the reduction in hazard from decay that the future Tim McVeigh would encounter with his radiological dispersion weapon.
Regardless of whether the plutonium is dispersed or concentrated in Yucca Mountain, safeguards will be required for many thousands of years, which simply cannot be guaranteed.
Reasonable ones can, using reasonable assumptions. Unreasonable ones cannot. You cannot guarantee that a meteor will not crash down on my head today and kill me. Should I or my employer be required to provide a meteor shield? I cannot guarantee that tomorrow you will not be whisked away by an Invasion of the Saucer Men, and have all sorts of grotesque and unmentionable experiments and examinations be performed on you. Should you be required then to have alien abduction insurance? My point is that you can make a career out of postulating any number of unlikely and unreasonable occurrences that we can wring our hands over for eternity and not get anything done. We just can’t do serious work on that basis.
That said, let me say that the proposed Yucca Mountain plan is not my preferred choice either. I’d rather reprocess the material and get the usable energy-bearing stuff out for future use, as well as whatever other useful things we can get. That will tremendously reduce the volume of material that will ultimately have to be disposed of, and more efficiently utilize existing resources. But, the political reality is that it isn’t going to happen. Given that, Yucca Mountain is the best we can do. Will that change in the future? I hope so. But, until then, there are any number of sound technical, economic, and security arguments that support the idea of a single, central repository, rather than many dispersed ones.
I would agree with reprocessing waste, but that it is not inconsistent with building the facility at Yucca Mountain.
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