Disposition of weaponsgrade plutonium in westinghouse. Plutonium customarily used in nuclear weapons weapons grade pluto nium and plutonium separated from spent reactor fuel reactor grade pluto 9 see david albright, frans berkhout, and william walker, world inventory of plutonium and highly enriched uranium 1992, london. Security and nonproliferation the canadian nuclear faq. The blankets of thermal reactors are known to accumulate plutonium with an isotope composition close to that of weapon grade plutonium. Second, the increased radiation of reactor grade plutonium is a major impediment to its use in u. The department of energy is providing additional information related toa 1962 underground nuclear test at the nevada test site that usedreactor grade plutonium in the nuclear explosive. This report discusses the results of a simulation study involving the burnup of mixedoxide mox fuel in a westinghouse pressurizedwater reactor pwr. In contrast, weaponsgrade plutonium is almost pure pu239 more than 90 percent. The dimona nuclear reactor is used to produce plutonium used in atomic bombs. An analysis of the current february 2009 status and future potential of indias nuclear fuel cycle is presented in this book. In the book, jones shows that nuclear weapons can be manufactured using reactorgrade plutonium that have the same predetonation probability, size and weight as nuclear weapons using weapongrade plutonium. The eol isotopic composition of a molten salt fast reactor operating 60 years on weapon grade plutonium feed 094600 to unload 2414377 diverges less than expected from one operating on reactor grade plutonium feed 35524117 to unload 422461017 case, see.
The doe definition of reactor grade plutonium changed in 1976. Plutonium acquisitions federation of american scientists. Potential nuclear explosive yield of reactorgrade plutonium. Strongly inclined against weaponization of reactorgrade plutonium are a. Utilization of triso fuel with reactor grade plutonium in. A molten salt reactor msr is a class of nuclear fission reactor in which the primary nuclear reactor coolant andor the fuel is a molten salt mixture. The attractive forces depend on the composition of the polar cores. Specifically a successful test was conducted in 1962, which used reactor gradeplutonium in the nuclear explosive in place of weapon grade plutonium. The integral fast reactor ifr, originally advanced liquidmetal reactor is a design for a nuclear reactor using fast neutrons and no neutron moderator a fast reactor.
Plutonium isotopics nonproliferation and safeguards issues. This plutonium is clearly fuel grade, not reactor grade. Probably all sides of this debate will agree that only a modern design could even conceptually use reactor grade plutonium without a severe degradation in yield. Reactor grade plutonium is found in spent nuclear fuel that a nuclear reactor has irradiated for years instead of weeks or months, leading to transmutation of much of the fissile, relatively long halflife isotope 239 pu into other isotopes of plutonium that are less fissile or more radioactive. These differences between reactor grade and weapon grade plutonium are not nearly as important from a nonproliferation perspective as some have argued. Plutonium halflives, and weapon grade and reactor grade 20 isotopic concentrations, at given fuel discharges.
Next, let us assume that in converting from fertile to fissile material, we get a conversion factor of about 0. Thermalneutron reactors todays nuclear power stations can reuse reactorgrade plutonium only to a limited degree as mox fuel, and only for a second cycle. Fuel burnup nuclear reactor physics wiley online library. This poses a certain risk of proliferation since such plutonium, having a small content of higher isotopes and plutonium 238, may be used in weapons actually with no prior processing. This form requires a specially designed and operated reactor.
Phwr, and magnox models, the material compositions at a burnup level of 0. The bn800 reactor is a sodiumcooled fast breeder reactor, built at the beloyarsk nuclear power station, in zarechny, sverdlovsk oblast, russia. Explosive properties of reactorgrade plutonium science. First, a swift primer about how fission bombs work. Any study therefore necessarily depends upon reverse calculations based on the information that is available. In 20 i refuted this claim and demonstrated that the plutonium was indeed reactor grade. The mox was composed of uranium and plutonium oxides, where the plutonium was of weapons grade composition.
Spent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor usually at a nuclear power plant. The paper investigates the prospects of utilization of triso fuel made of reactor grade plutonium in candu reactors. Setting the record straight about plutonium production in. By that time, the united states had plenty of weapon grade plutonium and had no need to supplement it with reactor grade plutonium.
The reactor was purchased from france as part of a secret agreement related to the suez war, in which the i. In contrast, the weapons grade plutonium produced in military reactors consists of over 93 percent. On the other hand, triso type fuel can withstand very high fuel burnup levels. In other words, increasing russias weapons plutonium disposition rate to 4mt a year would require utilising additional reactor capacity. Management and disposition of excess weapons plutonium. To reduce the concentration of pu240 in the plutonium produced, weapons program plutonium production reactors e.
Reactor grade plutonium is found in spent nuclear fuel that a nuclear reactor has irradiated burnupburnt up for years before removal from the reactor, in contrast to the low burnup of weeks or months that is commonly required to produce weapons grade plutonium, with the high time in the. Plutonium grades and nuclear weapons nuclearfree campaign. The last production reactor, ade2 in zheleznogorsk, was shut down in april 2010. Reactorgrade and weaponsgrade plutonium in nuclear explosives. Commercial plutonium a bomb material the japan times. In any event, public law 97415 prohibits united states defense use of plutonium produced in licensed facilities, i. The reactor grade plutonium is being processed into mox fuel. For the reactor grade plutonium curve, setting the spontaneous neutron emission rate at 20 x 10 5 per second is equivalent to choosing the mass as 10 kg, since the spontaneous emission rate of reactor grade plutonium is 200 nsg. The iaea applies similar safeguards measures to all plutonium, regardless of isotopic composition, apart from an exemption for plutonium containing 80% or more of the. Reactorgrade plutonium and nuclear weapons part one. Stacey second edition, completely revised and enlarged. The composition depends on the fuel burnup and the reactor type used. The mixture of thorium and weapons grade plutonium is the fuel for the new kind of reactors. Today, india may have deployed nuclear weapons using reactor grade plutonium.
Conceptually, because such a scheme has never been tested in the united statesnor elsewhere, to our knowledge. In the uk, the magnox reactors were designed for the dual use of generating commercial electricity as well as being able to produce plutonium for the countrys defence programme. Reactor grade plutonium is significantly more radioactive which complicates its use in nuclear weapons. The total doe plutonium acquisitions for the period 1944 to september 30, 1994, were 111. According to hans blix, then iaea director general. Isotopic uranium and plutonium denaturing as an effective method. Isotopic uranium and plutonium denaturing as an effective. Grade uranium and plutonium composition of weapons. According to the curve, there will always be a yield ratio of at least 2. Before this, three grades were recognised, the change in definition for reactor grade, from describing plutonium with greater than 7% pu240 content prior to 1976, to reactor grade, being defined as containing 19% or more pu240. Reactor grade plutonium is defined as material composed of more than 18% 240pu. For this calculation, weapongrade plutonium has the composition of 93. B reactor irradiate the uranium for a far shorter time than is normal for a nuclear power reactor.
There is substantial worldwide experience with the use and behavior of reactor grade plutonium, because all operating reactors contain plutonium created during the fission process. Fuel burnup nuclear reactor physics, second edition. Although the greater heat emissions from reactorgrade material would complicate the engineering of the weapon, this problem is surmountable. As is known, weapongrade plutonium wgpu consists mainly of 239pu with. The reactor grade material contains an admixture of undesirable plutonium isotopes other forms of plutonium. Estimating indias nuclear weaponsproducing capacity. Bomb designs utilizing reactor grade plutonium would also require a somewhat larger critical mass of plutonium, and would need to account for the greater heat generated by pu238. The long term operation has eliminated a major part of the. Weaponusable plutonium includes plutonium separated from the spent fuel of commercial reactors reactor grade plutonium and plutonium recovered from dismantled nuclear weapons weapon grade. Scientists create new material for nuclear reactors. Exploding the myths, longtime defense analyst gregory s. The isotopic composition of plutonium is affected by how long it stays in the reactor. Lengthy irradiation of uranium fuel can change significantly isotopic composition of uranium in particular, isotopes 232 u and 236 u do appear. Sergey bedenko says, large amounts of weapons grade plutonium were.
Designs using reactorgrade plutonium with no yield reduction. Jones draws from his decades of research using publicly available, unclassified information to debunk the persistent fallacy that reactor grade plutonium cannot be used to build reliable nuclear weapons. Plutonium in use federation of american scientists. Exploding the myths on the first question, the good news is that iaea safeguards do not differentiate plutonium based on its isotopic composition. If all three reactors were producing weapon grade plutonium, and they would have likely all been capable of doing so by about 2000, then they would have been producing 280 kilograms of weapon grade plutonium per year, assuming a capacity factor of 85 percent. This study evaluated the standard of westinghouse ap reactor and zrb2 as integral fuel burnable absorber ifba. Reactorgrade plutonium can be brought to a supercriticaland, hence, explosivestate by any assembly system that can handle u235. Ifr would breed more fuel and is distinguished by a nuclear fuel cycle that uses reprocessing via electrorefining at the reactor site. Weapon grade plutonium is defined as plutonium containing no more than 7 percent plutonium 240. Short exposures produce plutonium with very little pu240 and with very little plutonium being consumed by fission. Weapon grade plutonium separated at dedicated reprocessing plants located at the same three sites. In the united states, plutonium containing between 80 and 93 percent plutonium239 is referred to as fuelgrade plutonium, while plutonium with less than 80 percent plutonium239 typical of plutonium in the spent fuel of lightwater and candu reactors at normal irradiation.
Why is weapon grade plutonium better than reactor grade plutonium in weapons. Bombs, reprocessing, and reactor grade plutonium scgi. Plutonium isotope composition as a function of fuel exposure in a pressurizedwater reactor, upon discharge. Jones book ought to be the last word on the matter. Table 1 isotopic composition of first discharge plutonium from bushehr 1. So, plutonium produced in power reactors reactorgrade plutonium, rgpu contains the larger amounts of heavier plutonium isotopes. Reactor grade plutonium and heavy water moderator can give a good combination with respect to neutron economy. Each of the plutonium isotopes is sufficiently fission able that the separated isotope in metal form could provide a bare critical mass, so that a bare critical assembly could be made with plutonium metal no matter what its isotopic composition might be. Jun 06, 2014 rather, the united states recognized the dangers of reactor grade plutonium and applied pressure to france to block the sale of the reprocessing plant needed to produce separated reactor grade plutonium. The change in the definition for reactor grade, from describing plutonium with greater than 7% pu240 content prior to 1976, to reactor grade being defined as containing 19% or more pu240. Next to the rate at which uranium is being mined 46,403 tonnesyr, this is not enough to stave off peak uranium. The weapon plutonium reprocessing facility at mayak was shut down in 1987, after which the fuel from the mayak reactors was sent to tomsk7 for reprocessing. Computational and experimental forensics characterization of.
In the united states, plutonium containing between 80 and 93 percent plutonium239 is referred to as fuelgrade plutonium, while plutonium with less than 80 percent plutonium239 typical of plutonium in the spent fuel of lightwater and candu reactors at normal irradiation is referred to as reactorgrade plutonium. Can reactor grade plutonium be used in nuclear weapons. More precisely, weapons grade plutonium is obtained from uranium irradiated to a low burnup. Hence the simplest type of nuclear explosive, a gun type, in which the optimum critical. In the generic thermal reactor described above, only a small fraction of the. To date the isotopic composition of plutonium has not been a major issue for safeguards, because most plutonium under safeguards is of a similar composition, ie reactorgrade. Reactorgrade and weaponsgrade plutonium in nuclear. The plutonium 240 content even in weapons grade plutonium is sufficiently large that very rapid assembly is necessary to prevent preinitiation.
Thorium reactors may dispose of enormous amounts of. In fissile material, a free neutron may do any of several things. Composition of weapons grade uranium and plutonium. Controlling the flow of weaponusable fissile materials rand. Reactorgrade plutonium use in weapons would cause concern over radiation exposure to military service personnel. It is technically easier to build weapons from uranium than plutonium. Such a fuel cycle assessment is important, but relatively opaque because india regards various aspects of its nuclear fuel cycle as strategically sensitive. Typical reactor grade plutonium recovered from reprocessing used power reactor fuel has about onethird nonfissile isotopes mainly pu240 d. Certainly it is known that nuclearweapons states themselves have little use for reactor grade plutonium. The reactor is designed to generate 880 mw of electrical power. Reactor grade plutonium with any level of irradiation is a potentially explosive material. May 31, 2017 but it seizes on the difference between weapon grade plutonium and reactor grade plutonium, the latter coming from spent fuel that has been irradiated for a much longer time than weapon grade. Plutonium manufacture and fabrication nuclear weapon.
Reactorgrade plutonium can be used to make powerful and. The production of fissile materials for nuclear weapons. May 15, 2014 a commercial power reactor creates many isotopes of plutonium, including pu239, pu240, pu241, and pu242. Weaponusable fissile materials are defined as uranium with a fissile isotopic content of 20 percent or more and plutonium of any isotopic composition. The plant was considered part of the weapons grade plutonium management and disposition agreement signed between the united states and russia, with the reactor part of the final step for. As an example, isotopic composition of uranium fuel initial enrichment 4. This pamphlet discusses plutonium from discovery to its production, separation, properties, fabrication, handling, and uses, including use as a reactor fuel and.
A high content of the plutonium 240 isotope reactor grade plutonium is a complication, but not a preventative. The plutonium composition of pu1 see table 10 was chosen with a radius of the reactorgrade plutonium sphere of 5. Theft of separated plutonium, whether weapons grade or reactor grade, would pose a grave security risk. If approved by nrc, the reactor licensee would test the mox fuel by first operating with a few lead test assemblies in the reactor for at least two operating cycles. Questions persist in some nonproliferation policy circles as to whether a bomb could be made from reactor grade plutonium of high burnup, and if so, whether the task would be too difficult for a threshold state or terrorist group to consider. Fast reactors and nuclear nonproliferation problem. It is also essential that the future arms control treaties like the fmct subject all plu tonium regardless of its isotopic composition to treaty provisions. It is no longer useful in sustaining a nuclear reaction in an ordinary thermal reactor and depending on its point along the nuclear fuel cycle, it may have considerably different isotopic constituents. Reactorgrade plutoniumrgpu is the isotopic grade of plutonium that is found in spent nuclear. Long exposures produce high pu240 concentrations, and a substantial portion of the plutonium produced is consumed by fission. Jan 30, 2018 thorium reactors may dispose of enormous amounts of weapons grade plutonium jan 22, 2018 finding that nitrogen can combine with oxygen in zirconia to form no may lead to safer materials for.
748 827 1265 856 22 550 481 1241 713 338 809 646 716 280 416 310 181 1619 1054 71 417 1141 1463 1500 358 1349 1588 532 1013 1239 349 1469 658 805 943 151 967 1465 1023