Irradiation reactor

Nuclear Waste. NRC defines high level radioactive waste to include (/) irradiated (spent) reactor fuel (2) Hquid waste resulting from the operation of the first cycle solvent extraction system, and the concentrated wastes from subsequent extraction cycles, in a faciHty for reprocessing irradiated reactor fuel and (3) soHds into which such Hquid wastes have been converted. Approximately 23,000 metric tons of spent nuclear fuel has been stored at commercial nuclear reactors as of 1991. This amount is expected to double by the year 2001. 

Mager, T. R. and Marschall, C. W. 1984 Development of Crack Arrest Data Bank Irradiated Reactor Vessel Steels. 2, EPRI NP-3616, Palo Alto, CA, July. 

J. Price, Thermal conductivity of neutron-irradiated reactor graphites, 1974, General Atomics. 

Large-scale plutonium recovery/processing facilities originated at Los Alamos and Hanford as part of the Manhattan Project in 1943. Hanford Operations separated plutonium from irradiated reactor fuel, whereas Los Alamos purified plutonium, as well as recovered the plutonium from scrap and residues. In the 1950 s, similar processing facilities were constructed at Rocky Flats and Savannah River. 

Irradiated Fuel A historically important and continuing mission at the Hanford site is to chemically process irradiated reactor fuel to recover and purify weapons-grade plutonium. Over the last 40 years, or so, several processes and plants— Bismuth Phosphate, REDOX, and PUREX—have been operated to accomplish this mission. Presently, only the Hanford PUREX Plant is operational, and although it has not been operated since the fall of 1972, it is scheduled to start up in the early 1980 s to process stored and currently produced Hanford -Reactor fuel. Of nine plutonium-production reactors built at the Hanford site, only the N-Reactor is still operating. 

Plutonium Scrap Processing. In addition to recovering plutonium from irradiated reactor fuel, a Plutonium Reclamation Facility (PRF)( 7,8) is operated at the Hanford site to recover, separate, and purTfy kilogram amounts of plutonium from a wide range of unirradiated scrap materials. A 20 percent TBP-CC1 k solution is used to extract Pu(IV) from HN03-HF-A1(N03)3 solutions of dissolved scrap. 

The oral LDso in rats for 40% hydrogenated terphenyls (reactor coolant) was 17.5 g/kg for irradiated reactor coolant it was 6g/kg. Ingestion by mice for 16 weeks of the irradiated mixture at 1200mg/kg was lethal, whereas the nonirradiated mixture was not lethal but did cause irreversible interstitial nephritis. At 250mg/kg, no lesions were observed for tbe 16-week period of exposure. 

Eight samples of un-irradiated reactor pressure vessel (RPV) steel, two each from Trawsfynydd (TRA), Dungeness A (DNA), Sizewell A (SXA) and Bradwell (BWA) reactors were analysed. ICP-MS analysis was carried out using a high resolution magnetic sector instrument. Despite the sensitivity of this method, i.e. lower limit of detection (LLD) of around 8 pg g for procedural blanks, it failed to detect Li and achieved a detection limit of 80 ng g, which was well above the level of interest. However, the results were consistent and did show that the Li concentration was well below that found from the earlier analytical attempts (ICP-OES) and below the levels conservatively assumed in the waste inventory assessments. 

The group of radionuclides to be considered are the ones produced by nuclear explosions and the ones present in the irradiated reactor fuel. This group comprises several hundred radionuclides, but only a limited number of them contributes significantly to human exposure. These would normally include fission products and activation products. Radioactive noble gases, e.g. Kr, Xe, are not considered since they are unlikely to contribute significantly to internal exposure via the food chain. 

Analytical description of the CEC and MD kinetics in irradiated reactor steels... 

Gokhman, F., Bergner, A., and Ulbricht, U. (2005) Iron matrix effects on cluster evolution in neutron irradiated reactor steels, 9th Research Workshop Nucleation Theory and Applications, Joint Institute for Nuclear Research, 25 June - 3 July, Dubna, in Schmelzer, J. W., Roepke P., Priezzhev, V. B. (eds.) (2006) Nucleation Theory and Applications, J/VRPwM, 408-419... 

Although packed columns are simple and have no moving parts, their large space requirements have resulted in the replacement of packed columns by pulsed columns, or by other more compact contactors, in more recent installations for reprocessing irradiated reactor fuel. 

The radioactive decay properties of the plutonium isotopes that appear in irradiated reactor fuel are listed in Table 9.14. All but Pu and Pu are alpha emitters. Because it penetrates matter only weakly, alpha radiation is stopped by the outer layer of dead skin and is not a hazard outside the body. However, plutonium is very effective biologically when deposited in or on living tissue, particularly if by inhalation or by contaminated injuries. Pu is a relatively short-lived (13.2-year... 

The chemistry involved in the isolation and purification of the actinide elements from irradiated reactor fuel elemmts is further discussed in Chapter 21. Actinide chemistry in the ecosphere is discussed in 22.6. 

Another possible approach is the use of less meaningful apparent rates of photoconversion employing a different basis, such as in the case of Vfrr, the irradiated reactor volume. Thus, the basic balance, as described in equation (1-12), becomes... 

During the process of calculating the rates of photoconversion, frequently researchers make no distinction between the total reactor volume, V, and the irradiated reactor volume. It should be stressed that only under very special conditions and designs one can adopt the V = Vj r assumption and consider an apparent rate of photoconversion directly obtained from the change in concentration of an i chemical pollutant species. 

Two subcategories branch off from solar illuminated reactors nonconcentrating reactors and concentrating reactors. Non-concentrating solar irradiated reactors employ intensities equal or lesser than natural solar irradiation while concentrating solar reactors use irradiation intensities that surpass irradiations equivalent to one sun. 

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