Nuclear reactors containment

Nuclear Fuel Reprocessing. Spent fuel from a nuclear reactor contains Pu, Th, and many other radioactive isotopes (fission... 

Nuclear Fuel Reprocessing. Spent fuel front a nuclear reactor contains - tsy easy cwpu Mc-py, ant many other radioaclive isnlopes (fission products). Reprocessing involves the treatment of the spent fuel to separate plutonium and unconsumed uranium from other isotopes so that these can be recycled or safely stored. 

Enclosures are typically designed for low pressures in the inches-of-water range. Other designs, such as those for nuclear reactor containment, are rated much higher, but cost much more. To function properly as an enclosure, a stmcture should be airtight and able to be purged and vented if a release occurs. 

Hoffheins, B. S., Lauf, R. J., McKnight, T. E., Smith, R. R. and James, R. E. 1997, Evaluation of a hydrogen sensor for nuclear reactor containment monitoring, Proceedings of the International Topical Meeting on Advanced Reactor Safety, American Nuclear Society, 1 609. 

A nuclear reactor containing only fuel elements would be unusable because a chain reaction could probably not be sustained within it. The reason is that nuclear fission occurs best with neutrons that move at relatively modest speeds, called thermal neutrons. But the neutrcns released from fission reactions tend to be moving very rapidly, at about 1/15 the speed of light. In order to maintain a chain reaction, therefore, it is necessary to irrtroduce some material that will slow down the neutrcns released during lissicn. Such a material is known as a moderator. 

A typical electrical generating plant has a capacity of 500 megawatt (MW 1 MW = 10 J s ) and an overall efficiency of about 25%. (a) The combustion of 1 kg of bituminous coal releases about 3.2 X 10 kj and leaves an ash residue of 100 g. What weight of coal must be used to operate a 500-MW generating plant for 1 year, and what weight of ash must be disposed of (b) Enriched fuel for nuclear reactors contains about 4% U, fission of which gives... 

Although waste from nuclear reactors may not be produced in quantities that are large compared to radioactive hospital waste, it is far more dangerous. For example, spent fuel rods from nuclear reactors contain both short-lived and long-lived radioisotopes produced by collisions of fast-moving particles with atoms in the nuclear fuel and in the walls of the reactor itself. These rods are usually stored at the reactor site for several decades until the isotopes with short half-lives have decayed. 

Different categories apply to the hydrogen issue in nuclear reactor containments. During normal operation, small quantities of H2 are generated by radiolysis of the coolant, 44 H2 and 22 O2 molecules per 10 eV of neutron radiation energy. Under accident conditions, significant amounts of hydrogen could be produced due to radiolysis and corrosion reactions. 

MURPHY, B, Japanese Industry Turns to Sandia to Test Nuclear Reactor Containment Building Safety, Sandia LabNews, December 20, 1996. 

A better approach is given by the numerical calculation models. Detonation codes have been developed at the Research Center Karlsruhe, DETID and D3D, to determine the characteristic parameters within the reaction zone and outside in the unbumt mixture [20, 95, 100]. These models consider a homogeneous mixture of H2, O2, N2, H2O and are mainly applied to examine the load on a nuclear reactor containment. Validation was made against the above mentioned balloon tests of the Fraunhofer Institute and the Russian RUT experiments. Parameter calculations of 3D detonation have shown that the 3D structure is unimportant for the pressure load and that a relatively coarse grid provides sufficient accuracy [20]. 

A French radioisotope production group provided radionuclides such as Cr, Fe, Cu, Zn, and As by the Szilard-Chalmers processes (Henry 1957). At the Japan Atomic Energy Research Institute, this process was applied to obtain pure from neutron-irradiated potassium phosphate. Ordinary products using (n,p) reaction in a nuclear reactor contain an impurity isotope P in P, but P produced by (n,y) reaction in neutron-irradiated phosphate does not contain P. Hot atom chemically obtained P by (n,y) reaction was therefore appropriate for some special experiments in which contamination of P with different half-life and P-particle energy had to be excluded (Shibata et al. 1963). 

Quan, R. C., Evans, G. J. The impact of organic compounds on pH and iodine volatility in nuclear reactor containment structures. J. Radioanal. Nucl. Chemistry Articles 180, 237-243 (1994)... 

Pyramids, Toxic Wastes and Nuclear Reactors Containments... 

Pressure Behavior in a Nuclear Reactor Containment following a Loss of Coolant Accident", by M.S. Khattab, N.A. Ibrahim and S.D. Bedrose, AEA Cairo... 

R.K. Kumar, G.W. Koroll, Hydrogen combustion mitigation concepts for nuclear reactor containment buildings. Nucl. Safety 33, 398 14 (1992)... 

J.R. Travis, A heat, mass, and momentum transport model for hydrogen diffusion flames in nuclear reactor containments. Nucl. Eng. Design 101, 149-166 (1987)... 

It is of interest to consider whether impairment of heat transfer would be encountered under the conditions likely to be achieved in a buoyancy-driven flow system of the kind which has been proposed for passively cooling a nuclear reactor containment vessel. In this connection, a further matter needs to be considered. Most of the experimental studies of mixed convection reported to date have been carried out with a thermal boundary condition of uniform wall heat flux. However, in the case of a severe accident in a pressurised water reactor, where steam is released from the core into a steel containment vessel and is condensing on its inside surface, the vessel will take up a uniform temperature. Since the nature of the thermal boundary condition could certainly affect the process of heat transfer to the air, there is a need to consider whether the behaviour with uniform wall temperature will be similar to that with uniform wall heat flux. 

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