Irradiation plant design

A whole plant design optimization increases the reactor thermal output from 100 to 140 MWt. The fast neutron flux increases about 30% as shown in Fig. 27 and the maximum allowable number of fuel irradiation test rigs increases from nine to twenty-one. The MK-III core will support various irradiation tests on advanced fuels like MA doped fuel, high plutonium content MOX fuel and vibration packed fuel. The irradiation technology has also been developed to expand the capability and flexibility of fuels and materials irradiated. 

The main objectives in designing a commercial irradiation plant are a high utilization of the radiation energy, i.e., high efficiency, and a uniform dose throughout the product. Other considerations include a minimum holdup time in the process and ease of replenishing the radioactive source. 

Several of the early designs of irradiation plants incorporated a deep water pond in the irradiation chamber into which the source frame was lowered under gravity. A water pond has several advantages, such as the following ... 

However, unlike photosynthesis in green plants, the titanium oxide photocatalyst does not absorb visible light and, therefore, it can make use of only 3-4% of solar photons that reach the Earth. Therefore, to address such enormous tasks, photocatalytic systems which are able to operate effectively and efficiently not only under ultraviolet (UV) but also under sunlight must be established. To this end, it is vital to design and develop unique titanium oxide photocatalysts which can absorb and operate with high efficiency under solar and/or visible-light irradiation [9-16]. 

We have now embarked on a program to realize this potential. The U. S. Rubber Co. and Martin-Marietta Corp. have created a new, jointly-owned subsidiary—Isochem, Inc. This new company will build a fission product conversion and encapsulation plant at the Hanford, Wash., reservation to produce fully encapsulated fission products for commercial use (5). The plant is designed with four separate production lines, each for a different fission product. The capacity of each line varies with the process involved and the batch sizes and processing time. The capacity of the single line normally used for cesium-137 has been set at 29 million curies per year to meet the projected market demands of the early 1970,s (1). At these production quantities, cesium-137 should be available at less than ten cents per curie for large irradiators. 

A small pilot plant for the photochlorination of hydrocarbons consists of an ideal tubular-flow reactor which is irradiated, and a recycle system, as shown in the sketch. The HCl produced is separated at the top of the reactor, and the liquid stream is recycled. The CI2 is dissolved in the hydrocarbon (designated as RH3) before it enters the reactor. It is desired to predict what effect the type of reactor operation will have on the ratio [RH2Cl]/[RHCl2] in the product stream. Determine this ratio, as a function of total conversion of RH3, for two... 

Plants, allowing to carry out irradiation both in aerial and airless media [233] are designed for studying oxygen effect on the rate of photodestmction. 

Electric wires and cables used in nuclear power plant are exposed by low dose rate irradiation during the life time of the plant. In addition, loss of coolant accident (LOCA) that is a design basis accident brings about the degradation by heat and radiation on the electric wire and cables. The dose varies from plant to plant. IEEE std.323-1974 (/) estimated the dose 0.5 MGy for the period of the life time and 1.5 MGy for LOCA as one of the example. The standard estimated 40years and one year, for the lifetime of plant and duration of LOCA respectively. 

The first microgram quantities of plutonium were produced [S6] in 1942 by irradiation of natural uranium with deuterons in the cyclotron of Washington University in St. Louis. This plutonium was separated at the Chicago Metallurgical Laboratory of the Manhattan Project by Seaborg and his collaborators, who employed the method of carrier precipitation frequently used by radiochemists to extract small amounts of radioactive material present at low concentration. As wartime urgency required that a plutonium separation plant be designed and built before macro quantities of plutonium could be available for process development, it was decided to use the same carrier precipitation process that had successfully produced the first small quantities of this element. 

In the Aquafluor process [G4] developed by the General Electric Company, most of the plutonium and fission products in irradiated light-water reactor (LWR) fuel are separated from uranium by aqueous solvent extraction and anion exchange. Final uranium separation and purification is by conversion of impure uranyl nitrate to UFg, followed by removal of small amounts of PuF , NpFg, and other volatile fluorides by adsorption on beds of NaF and Mgp2 and a final fractional distillation. A plant to process 1 MT/day of irradiated low-enriched uranium fuel was built at Morris, Illinois, but was never used for irradiated fuel because of inability to maintain on-stream, continuous operation even in runs on unirradiated fuel. The difficulties at the Morris plant are considered more the fault of design details than inherent in the process. They are attributed to the attempt to carry out aqueous primary decontamination, denitration, fluorination, and distillation of intensely radioactive materials in a close-coupled, continuous process, without adequate surge capacity between the different steps and without sufficient spare, readily maintainable equipment [G5, R8]. 

The principal radionuclides to be discharged from the plant as originally designed are gaseous tritium and Kr. The 100-m stack provides adequate dilution and dispersion. Equipment for removing Kr will be added when fuel irradiated after 1982 is to be reprocessed. 

In the use of radioactive tracers it is assumed that the radioactive isotopes studied are identical in chemical behavior to the nonradioactive isotopes. The first experiments that used radioactive tracers were carried out in 1913 in Germany and were designed to measure the solubility of lead salts via the use of a radioactive isotope of lead. In industry, radionuclides have been used for analytical purposes, for measurements of flow in pipes, and as part of many other apphcations. Another example of an important tracer study has been the investigation of photosynthesis of carbohydrates from atmospheric CO2 in the presence of light and chlorophyll. Scientists used eC, 15P, and iH to identify the intermediate steps involved in the photosynthesis of carbohydrates in plants that had been placed in an atmosphere composed of fyC-labeled CO2 and had been irradiated with hght. The presence of the radioactive carbon in the synthesized carbohydrate was evidence that O2 was involved in the synthesis. 

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