Light-water reactors limits

Kang, J., von Hippel, F. 2005. Limited proliferation-resistance benefits from recycling unseparated transuranics and lanthanides from light-water reactor spent fuel. Science and Global Security 13 169-181. 

Presently, plutonium is used in light-water reactors as MOX fuel and also in small amounts for the development of fast-breeder reactors. Currently 22 power reactors in five countries (France, Germany, Switzerland, Belgium, and Japan) are loaded with MOX fuel and this number is expected to rise to between 36 and 48 by 2000. The use of MOX reduces the inventory of separated plutonium and is regarded as an interim measure before plutonium s possible full-scale use in fast reactors later in the next century. It is known that multiple recycling in light-water reactors degrades plutonium, which in turn limits the number of times it can be recycled to two or three. Such... 

The nuclear fuel consists of uranium, usually in the form of its oxide, U3O8 (Figure 23.12). Naturally occurring uranium contains about 0.7 percent of the uranium-235 isotope, which is too low a concentration to sustain a small-scale chain reaction. For effective operation of a light water reactor, uranium-235 must be enriched to a concentration of 3 or 4 percent. In principle, the main difference between an atomic bomb and a nuclear reactor is that the chain reaction that takes place in a nuclear reactor is kept under control at all times. The factor limiting the rate of the reaction is the number of neutrons present. This can be controlled by lowering cadmium or boron rods between the fuel elements. These rods capture neutrons according to the equations... 

This section provides a comparison of power reactors built in the UK with the Soviet RBMK. But it is worth recollecting that, elsewhere in the world, other types of power reactors are in use. The most widely built reactor is the Pressurised Water Reactor (PWR) but the second is the Boiling Water Reactor (BWR), a light water reactor in which, like the RBMK, steam is generated in the core and passed to the turbines in a direct cycle. Light (i.e. ordinary) water is used as coolant and moderator. The Canadian industry has developed the CANDU series of reactors, with limited export to India, etc., which have many pressure tubes to retain the coolant, as in the British SCHWR and Soviet RBMK, but are heavy-water-cooled and moderated. 

Commercial fabrication of uranium oxide fuels for light-water reactors is the fastest maturing segment of the nuclear fuel cycle. Some ten commercial fuel faibii-cators now routinely manufacture uranium fuels bn a more or less mass production basis. With this maturing comes an increased incentive to increase production rates and thereby reduce fuel fabrication costs. One astutely observes that the criticality safety. K, therefore, behooves us to periodically reexamine plant equipment in light of advances in criticality safety technology and to adjust limits wherever possible to enhance the economics of the fuel cycle. 

Beaudoin, R.R. and P. Pattantyus. 1997. Comparison of Dry Fuel Storage Costs and Required Land Area for CANDU 9 and Light Water Reactors (LWRs) in South Korea, Appendix B in Atomic Energy of Canada Limited Report. AECL-11892,41-48. 

When information on the production and transport of the radionuclides in the primary system is requested, it is not sufficient to limit the analyses to those isotopes that are relevant for dose rate buildup such as °Co, Co, and Mn. As will be discussed in the following sections, there are two different possible sources of radionuclides in the primary circuit of light water reactors the materials located permanently in the core region and those located outside the neutron field from which corrosion products are transported to the reactor core and are temporarily deposited there. With regard to the production of radionuclides, the main difference between these two sources is the residence time of the substances in the neutron field, which is equivalent to its activation period for this reason, determination of the element specific activity, i. e. the activity of a given long-lived radionu-... 

Because of these differences in the conditions compared with an LWR severe accident, and because of the limited number of measurements performed, the data obtained here have not been introduced into the evaluations of the consequences of severe light water reactor accidents, so that the high degree of retention of fission product iodine within the plant which was observed in the TMI-2 accident turned out to be an unexpected and surprising fact for the accident analysts. 

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