Radioactive material, fissile

A D—T fusion reactor is expected to have a tritium inventory of a few kilograms. Tritium is a relatively short-Hved (12.36 year half-life) and benign (beta emitter) radioactive material, and represents a radiological ha2ard many orders of magnitude less than does the fuel inventory in a fission reactor. Clearly, however, fusion reactors must be designed to preclude the accidental release of tritium or any other volatile radioactive material. There is no need to have fissile materials present in a fusion reactor, and relatively simple inspection techniques should suffice to prevent any clandestine breeding of fissile materials, eg, for potential weapons diversion. 

Since the amount of fissile material in the fuel assemblies is only about 3 percent of the uranium present, it is obvious that there cannot be a large amount of radioactive material in the SNF after fission. The neutron flux produces some newly radioactive material in the form of uranium and plutonium isotopes. The amount of this other newly radioactive material is small compared to the volume of the fuel assembly. These facts prompt some to argue that SNF should be chemically processed and the various components separated into nonradioac-tive material, material that will be radioactive for a long time, and material that could be refabricated into new reactor fuel. Reprocessing the fuel to isolate the plutonium is seen as a reason not to proceed with this technology in the United States. 

Radioactive Material From 49 CFR 173.403, a radioactive material is any material having a specific activity greater than 0.002 microcuries per gram (uCi/g). Specifications and descriptions can be found in the regulations. The reader may also refer to the term fissile material in this glossary. 

Aqueous reprocessing methods have been developed to effect an efficient and thorough separation of fissile elements from the contaminating fission products in spent fuel( l). While these processes may be altered to yield a proliferations-resistant product by coprocessing or by the addition of radioactive material that will contaminate the clean fissile material, it still is necessary to safeguard some of the process steps to ensure that material useful in nuclear weapons will not be diverted (3). The safeguard requirements and the ease of subversion of such provisions make many versions of the conventional processes subject to unacceptable proliferation risks. 

This brief discussion of the Purex process is expanded in Chap. 10, which discusses other processes for treating irradiated fuel and which deals with novel aspects of processing highly radioactive and fissile materials. 

A RADIOACTIVE WHITE-I label must be affixed to each package measuring 0.5 miUirem or less per hour at each point on the external surface of the package, provided the package is not a Fissile Class II or EH, or does not contain a large quantity of radioactive material, as defined in Section 173.389 of the regulations... 

The reactor core is the heart of any nuclear reactor and consists of fuel elements made of a suitable fissile material. There are presently four radioactive materials that are suitable for fission by thermal neutrons. They are uranium-233 uranium-235 plutonium-239 ( Pu),... 

Transportation regulations quantify the risk of radioactive materials by considering the type and degree of radiation, the critical mass of fissile materials, and the heat generated by the radiation. 

LSA I material is (a) ores containing naturally occurring radionuclides, e.g. uranium, thorium, and uranium or thorium concentrates of such ores (b) solid, unirradiated natural uranium or depleted uranium or natural thorium or their solid or liquid compounds or mixtures or (c) radioactive material, other than fissile material, for which the A2 value is unlimited. lATA 10.3.5.1.1... 

Radioactive materials are grouped according to their form and/or characteristics. These include Special Form Low Specific Activity (LSA) Surface Contaminated Object (SCO) Fissile Other Form. A radioactive material may meet the definition of one or more of the above. lATA 10.3.3... 

The physical protection of fissile and radioactive materials and of nuclear power plants as a whole is mentioned where appropriate but is not treated in detail obligations of States in this respect should be addressed on the basis of the relevant instruments and publications developed under the auspices of the IAEA. Non-radiological aspects of industrial safety and environmental protection are also not explicitly considered it is recognized that States should fulfil their international undertakings and obligations in relation to these. 

Testing before the introduction of fissile and radioactive material... 

A. 8. The inspection area of testing before the introduction of fissile and radioactive material encompasses those activities and tests performed before the introduction of such material by the operator in order to demonstrate that SSCs function properly and conform to design requirements. It also covers the inspection and acceptance criteria for the receipt at the facility of fissile and radioactive material. The regulatory inspection programme should include ... 

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