by Vera PARAFONOVA, science writer
Scientists from a nuclear research center at Snezhinsk (its former code name was Chelyabinsk-70; today this is a federal center for nuclear research - All-Russia Scientific Research Institute of Physics Technology) have come up with a really fantastic idea. They suggest - believe it or not - conducting what they call thermonuclear "mini explosions". For peaceful purposes - as a method of saving the world from the "energy famine", and ecological catastrophe into the bargain. And one can only hope and pray that these scientists really know what they are talking about. Indeed, there is no denying the fact that back in the 20th century Russian experts did save the world from global military conflicts by developing strategic nuclear and thermonuclear deterrents. And having said that, what other technical "wonders" can lie in store for us all in the 21st century?
But to begin from the beginning, the Snezhinsk experts say they are ready to design and build what they call the "core" power plant of "explosive" deuterium power industry - an explosive combustion atomic pile (KVS). Speaking in more common terms, what they have in mind is a ferroconcrete barrel, or tank, some 150 m in diameter, 200 m high and wall thickness of 35 m. On the inside the tank is lined with a 20 cm layer of steel and the whole structure is buried inside an earth mound more than one hundred meters high. The structure, code-named KVS-10, will also contain a protective liquid sodium "blanket" inside of which deuterium blasts will be conducted at intervals of half an hour. Such blasts of 10 kg trotyl equivalent will release 37 GWt of heat energy which is an equivalent of burning 25 mln tons of oil a year.
What makes the KVS idea attractive? The answer is provided by the head of the project, Dr. Gennady Ivanov: "There are really no basic problems in translating the idea into reality Most of the things required for a pilot power plant are already available. It has been quite some time since specialists learned to conduct thermonuclear explosions with energy releases of tens of tons and even one kiloton. And in our case the problem of dealing with high temperatures and pressures is eliminated since the reaction is triggered by an uranium or plutonium charge and the fuel is deuterium - an ecologically pure, inexpensive and readily available in unlimited quantities nuclear material obtained from ordinary water. This material, of course, will have to be exploded with the help of uranium or plutonium, but the quantities of these 'dirty' materials will be thousands of times less than those required by atomic power stations of similar capacity. And that means that there will be small amounts of radioactive wastes. And we suggest using in our KVS reactors not uranium-235 or plutonium-239, but uranium-233, which can be synthesized from thorium which is readily available in nature."
"Explosive" technologies, to use this general term, are quite common in our daily life. One most obvious example is that our cars are powered by internal combustion engines. Explosions of motor fuel in car cylinders produce pressures much greater than those expected in KVS. And that simply means that the methods suggested by the Snezhinsk experts is a "yesterday" of modem science. And the reasons for their revival are really tangible. Under the leadership of academicians Yevgeny Zababakhin, Yevgeny Avrorin and
Boris Litvinov they have developed "clean" deuterium charges for peaceful nuclear blasts. And there is no denying the historical fact that right from the start the research potential of the Center has been aimed not only at nuclear weapons and that some of its best brains were constantly concerned with peaceful uses of nuclear energy In the final analysis this has brought them to the problem of industrial uses of nuclear explosive devices. To this day the Institute remains the one and only center in the world where such devices are developed for economic applications. The list includes 14 such devices out of which 9 have been used for peaceful applications for nearly one hundred times. And Dr. Ivanov is no novice in this field, having been awarded a State Prize in 1983 for his research into the diagnostics of thermonuclear combustion.
The very first suggestions about using nuclear explosions for power production date back to the late 1940s. But Dr. Ivanov came into the picture some 15 years later and in the beginning these ideas failed to catch his imagination as compared with the dazzling prospects of controlled thermonuclear synthesis and breeder energetics* based on the reproduction, or breeding, of nuclear fuel. And it was some 25 years ago that Academician Andrei Sakharov - one of the fathers of the concept of "controlled thermonuclei" with the help of magnetic retention of plasma - was bold enough to finally reject these studies as erroneous. He substantiated his stand by pointing to the slow progress in controlled thermonuclear synthesis in breeders. This took off from the agenda the dream of producing something in between "solar combustion" and a full- scale blast while also achieving the required density of energy release in controlled thermonuclear synthesis. As Dr. Ivanov is saying now: "It took us but five years to obtain the conditions of thermonuclear combustion in bombs. And this, to my mind, produced the illusion that one can take a milligram, and bum it like a kilogram. It appears that some such experiments were conducted by the Americans and, I think, the outcome was just the same. But chances are that someone, somewhere and sometime will learn to produce such combustions."
But the time for dealing with this problem is really pressing. According to different expert assessments and different prognostications, the duration of the "petroleum era" in the history of mankind amounts to only 25 or 100 years from now. Natural gas reserves on our planet are not as rich as those of oil (in terms of energy) and are not being used up with such intensity And in the opinion of Dr. Ivanov both these fuels are likely to be exhausted at nearly one and the same time. And that means that out of the traditional fuels coal alone will be able to replace oil and gas in the near future. That being so, the rate of its consumption will increase tenfold in the next 25 years and will be 20 times greater than now in the next half a century And even then there can be enough coal for another hundred years. But coal is expensive to
* In breeder power engineering enriched uranium is used in what are called breeder reactors. By suitable design, more Pu-239 can be produced in their blanket than is required to enrich the fuel in the core. These reactors are 50 times more economical in uranium usage than thermal reactors. The most promising are breeder reactors on fast neutrons with a uranium-plutonium cycle. So far their fuel has been U-239, but in future this will be replaced with a mixture of U-238 and Pu-239. Currently used reactors on thermal neutrons "bum up" 0.5-1.0 percent of uranium and the use of breeder reactors can boost this factors by tens of times, providing a more reliable basis for the development of nuclear power engineering.- Ed.
mine and transport and pollutes the environment to a dangerous extent. The potential resources of uranium-238 are about the same as of coal. But atomic power stations will be able to use it only after reprocessing into plutonium in breeder reactors.* This, however, is still unprofitable with the present breeder factors. "For KVS, - Dr. Ivanov points out, - the problem of fuel does not exist. It is using hundreds of times less fissionable materials per unit of power."
Does that mean that a transition to KVS offers the only way of preventing an energy catastrophe? And what about safety? Addressing the participants of a recent international symposium "Electrical Engineering-2010", Dr. Ivanov said: "An energy- generating charge for KVS will be assembled by manipulators directly in the blast chamber from two fragments, or sections each of which taken separately presents no danger. Most we can expect is an explosion in the absence of the sodium protective shell in the chamber. According to calculations, the inner steel jacket will be badly damaged in this case, putting the pile out of operation, but there will be no leakage, or escape, of radioactive materials into the environment. The only concern is that the blast energy should not exceed the nominal level by 8 times. This is the strength limit of the ferroconcrete KVS shell with wall thickness of 35 m. Of course there is nothing unusual for the blast energy to deviate from the design mean value by 8 percent. But a difference of 8 times is something quite different? Hard as we tried, we failed to boost the blast energy even by 50 percent. And there are many ways of decreasing it."
But what about the regime of non-proliferation of nuclear materials? And what about the mounting menace of terrorism? Dr. Ivanov replies: "The fissionable material used in KVS cannot be piled up by a single terrorist, or a state. Using it right after its separation, the staff runs no risks. But after a period of one month a terrorist assembling a bomb will simply be doomed. And it is also useless stealing a complete charge of this kind because it looses its 'explosive potential' within one hour after the assembly. And the explanation is simple. Uranium-233 in the charge is bombarded with fast neutrons. And a neutron hitting an uranium nucleus strikes out of it with certain probability two particles, thus forming a nucleus ofuranium-232. And that has a half-life of 70 years which accounts for its high activity And protection from uranium radiation is no problem. But the chain of U-232 transformations includes thallium-208 which emits 'hard' (2.6 MeV) gamma radiation. And while the 'fuel' in the charge presents no threat during the first few hours because it contains no thallium, about a week later it should be handled by robots only So, let me say again that the fuel core of a reactor with uranium processed for KVS will be highly dangerous for man within a month after manufacture. The rate of thallium build-up continues to grow so that after some 25 hours one has to observe 'radiation safety standards', a week later the material becomes really dangerous and a month later it is fatally dangerous for the assembly staff, or even a person who may have to put it into some proper storage."
As Academician Sakharov wrote back in 1977 about a unit similar to KVS in an article entitled "Nuclear Power Engineering and Western Freedom": "I would not change places with a terrorist!"
"They are trying to convince us, - Dr. Ivanov went on, - that direct use of arms technologies in 'internal combustion piles' will produce a situation when some third countries will obtain 'ready-made' nuclear and thermonuclear weapons, because with respect to KVS technologies the non-proliferation regime is 'nothing but theory'. And if some military technologies are not excluded from the proposed peaceful applications, no special services will be able to prevent dangerous 'leaks' of information. And we simply have no choice because what we call 'slow' thermonuclear charge neither burns, nor even smolders. And if this effect could not be achieved after half a century of experiments, the problem is really complicated and chances of solving it are really small. But what if a solution is found after all? Well, then there will have to be experts who are much more 'clever' than what we have today and they would be able to 'put together' atom bombs from any reactor fuel and teach millions of 'boiler room operators' from thermonuclear synthesis facilities. And that would really be a most 'massive' leakage of nuclear technologies."
In the opinion of the Snezhinsk experts, a pilot KVS unit will put to the test all of the proposed technical solutions, generating commercial amounts of electricity over several years. What they call the minimal blast energy for such unit would most likely amount to 1 -2 kilotons in the TNT equivalent. And the cost will be between 100 to 600 mln dollars depending on the amounts of electricity produced, service life, safety margin, etc. A pile of this kind for municipal heating needs of the cities like Chelyabinsk and Yekaterinburg (1.5-2.0 GWt of heat per city) should cost no more than 300 min dollars according to the available expert assessments."
The project, of course, is yet to be "put on its feet". And while the "theory" is ready now, detailed technical solutions are yet to come. Nor are there the necessary funds to pay for all this work. But the main part of the way is already behind-a deuterium energy source is there already. So, what is yet to be done? What we need now is a decision of our political leaders for building a pilot plant. No more and no less. The "brainchild" of the Snezhinsk experts falls within the limits of the General Nuclear Test Ban Treaty The treaty does not ban their peaceful uses, as had been requested by the leaders of the Chinese People's Republic, but imposes some limitations which will leave any potential investors in the dark about the time limits of the KVS introduction. According to this document, a country wishing to conduct the appropriate tests should first prove their peaceful nature and that they are in accordance with the national interests.
"The Russian version of explosive deuterium power engineering offers many advantages, - says the head of the project Dr. Ivanov. - It is one of the few high technologies which is in line with our previous progress and which really meets the genuine needs of mankind."
* See: V. Subbotin, "Nuclear Power Safety", Science in Russia, No. 1, 1999. -Ed.
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