Radioactive materials classification

Classification of the material is more complex if hazards other than radioactivity are present. While Class 7 radioactive material classification takes precedence over other hazards (i.e., the regulations consider "radioactive" to be the highest hazard class), the presence of secondary chemical hazards must still be considered in radioactive shipment preparation, documentation, and execution. Refer to 49 CFR 173.2 for information on other hazard classes. 

Exempt Radioactive Wastes. The radioactive waste classification system in the United States does not include a general class of exempt waste (see Table 1.1). Rather, many products and materials that contain small amounts of radionuclides (e.g., specified consumer products, liquid scintillation counters containing 3H and 14C) have been exempted from requirements for use or disposal as radioactive material on a case-by-case basis. The various exemption levels are intended to correspond to low doses to the public, especially compared with dose limits in radiation protection standards for the public or doses due to natural background radiation. However, the exemption levels are not based on a particular dose, and potential doses to the public resulting from use or disposal of the exempt products and materials vary widely. 

Deficiencies in the Radioactive Waste Classification System. The classification system for radioactive waste in the United States summarized in Table 1.1 is based primarily on the earliest descriptions of different classes of waste that arises from chemical reprocessing of spent nuclear fuel and subsequent processing of nuclear materials that were developed beginning in the late 1950s. These wastes were considered to be the most important in regard to potential radiological impacts on workers. 

The classification system lacks a set of principles for determining when a waste contains sufficiently small amounts of radionuclides that it can be exempted from regulatory control as radioactive material. The lack of a general class of exempt waste increases in importance as the resources required for management and disposal of radioactive waste increase compared with the resources required for management and disposal of these materials as nonradioactive waste, and it may foreclose possible beneficial uses of slightly contaminated materials. 

A second consideration that has been important, at least implicitly, in developing classification systems for radioactive waste is natural background radiation. The presence of a ubiquitous and unavoidable background of radiation and its description in terms of radiation dose provide a measure of the significance of potential exposures of radiation workers and members of the public to any radioactive waste. Levels of radiation in waste materials compared with levels of natural background radiation have played an important role in radioactive waste classification. 

IAEA has been developing recommendations on classification of radioactive waste and principles for exempting radioactive waste from regulatory requirements for radioactive material for more than 30 y. This Section briefly reviews these developments. 

According to this classification an inflammable liquid or solid chemical is given a number designating its class, and a red color that indicates its physical or chemical hazard such as flammability. For toxic, corrosive, explosive radioactive material a container should be marked with different numbers and colors (Fig. 2.4). 

Following the classification of the analytical methods given by ISO 32 [3] two major type of calibration materials can be certified. For relative methods such as all spectrometric ones, pure substances are necessary. They can be certified for the stoichiometry and degree of purity but also for isotopic composition. The latter case is a prerequisite for measurements of radioactive materials and for stable isotope mass spectrometry (isotope dilution TIMS or ICP-MS). For comparative methods, pure substances and mixtures of substances are necessary, as well as matrix materials for which the element to be determined is perfectly known and also the major compounds that produce a matrix influence on the signal (e.g. alloys, gases). 

Radioactive substances of various activities, conc trations (or specific activities), decay modes, etc., constitute quite different hazards, and must be handled accordingly. Various countries classify radioactive material differently and issue different working rules. We give a few classifications and rules, adhering primarily to the recommendations of the IAEA. 

This classification is only qualitative and rigid health physics monitor- ing must always be carried on after radioactive material first enters the process equipment. The unique features of plant designs for such conditions will be discussed next. 

Hazard analysis results are summarized and displayed. A final hazard classification of the SNL HCF and the radioactive material storage areas, consistent with DOE-STD-1027-92, is also presented (DOE 1992b). Finally, a limited set of bounding hazards is Identified for further development using quantitative, deterministic techniques In Section 3.4, "Accident Analysis."... 

The hazard analysis is performed to 1) identify and evaluate potential acddents 2) identify bounding accident scenarios that require further quantitative development and 3) verify the initial hazard classification assigned to the HCF and associated radioactive material storage areas. 

FAIRBAIRN, A., MORLEY, E, KOLB, W., The classification of radionuclides for transport purposes , The Safe Transport of Radioactive Materials (GIBSON, R., Ed.), Pergamon Press, Oxford and New York (1966) 44 6. 

SCOs are not regulated for shipment if contamination is below the definition of contamination in 49 CFR 173.403. SCOs are also exempt from classification as radioactive material if the total activity on the surface can be demonstrated to be less than the activity limit for an exempt consignment (see 49 CFR 173.401(b)(5) as of 2014, and DOT interpretations 05-0145 dated July 1,2005, and 08-0012 dated May 7,2008 available on the PHMSA website, http //www.phmsa.dot.gov/hazmat/regs/interps). 

Much of the regulation of radioactive material shipment hinges on the A1/A2 value, and the classification and packaging of the material may fall in line after this determination is made. However, a large portion of radioactive material shipments make use of provisions for LSA material that falls outside of the A1/A2, Type A/Type B regulatory structure. 

The other piece of information needed is the solubility of the material. Radioactive materials are classified into three different solubility classes. Two different classification systems are used but both have the same purpose and in practice are used interchangeably. The first classification system is based on ICRP 26 (1977) and is also the basis for the tables contained in 10 CFR 20. This system classifies materials into solubility classes of D (day), W (week), or Y (year) according to the rate at which the material is absorbed out of the lungs and into the bloodstream. The second system is based on ICRP 66 (1994)... 

B7.3 EWLa-X Electrode Classifications. The EWLa-X electrodes are tungsten electrodes containing lanthanum oxide, referred to as lanthana. The advantages and operating characteristics of these electrodes are similar to that of the EWCe-2 electrodes. Unlike thoria, lanthana is not a radioactive material. 

---