Heat generation, radioactive processes

It is assumed that the average heat generation due to the radioactive processes described above was around 8x 10 6 J/g of rock (Birch, 1954). If this value is extrapolated to the Earth s crust (to a depth of 35 km), the result is 53 J/cm2/year. It seems clear that the crust of the primeval Earth contained about four times as much 40K as today. The higher half-life of 238U means that the amount of this isotope present about four billion years ago was around twice today s value. The corresponding factor for 235U, with a half-life of 7x 108 years, is 64. Thus, the value of... 

The nuclear processes can affect the properties of the atoms, and this can have an effect on the properties of materials that are made with those atoms. For example, there is often a lot of heat generated by radioactive atoms, and this heat can affect material properties. Did you know that much of the potassium in our body is in the form of a radioactive isotope This accounts for some of the heating within our own bodies (see Chapter 11). 

Primarily, radioactive effluents and wastes were generated within the 105-N reactor building and the 109-N heat transfer building. The radioactive process effluent and waste streams ultimately were sent to either the 116-N-l crib and trench, the 116-N-3 crib and trench, or the 1314-N liquid waste loadout station (LWLS). 

Heat generation by fission products. The problem of heat removal is an important consideration in the design of processes and equipment for handling radioactive fi.ssion products. This is particularly true in the present case, because of the relatively short age of the fission products at the time of their extraction from the fuel. However, heat removal from fused salts does not present a difficult problem. 

The process at Three Mile Island involved nuclear fission and subsequent reactor cooling using circulating water. The primary water was kept under pressure to prevent boiling. Heat was transferred to a secondary water system that supplied power to a steam generator. Upon completion of this step, steam condensate was recovered and recycled. All radioactive materials, including primary water, were enclosed in a lined concrete containment building to prevent their escape to the atmosphere. 

Three of the 300,000-gal tanks that do not contain cooling coils are used to store radioactive liquid wastes that do not generate any appreciable heat because the concentration of fission products is too low. One of these three tanks is retained as a spare in the event that failure of a process vessel containing radioactive solution contaminates normally non-... 

As uranium undergoes fission, the uranium atoms split and release neutrons. Some of these neutrons split other uranium atoms, which produce radioactive waste products. The net result of the fission process is the generation of intense heat which is used to generate steam for turning the generators. 

The remaining liquid after Pu and U are removed is high-level waste (HLW), containing about 3% of the spent fuel. It is highly radioactive and continues to generate a lot of heat. This waste must be immobilized and because of the presence of radioisotopes with long half-lives it must be immobilized for tens of thousands of years. Ceramics are key materials in this process. 

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