Radioactive materials, definitions

Where two or more authorities use the same definition with only differences in format or punctuation, the definition is not duplicated it is reproduced from its source according to the following hierarchy UN, IMDG, ICAO, US, and LATA. IAEA takes precedence for all definitions related to radioactive materials. Definitions differing in wording, spelling, or pluralization, however small, are considered unique. Corrections to regulatory definitions appear within brackets [ ]. 

The basic unit of radioactivity is the curie, Ci. One curie is the amount of radioactive material that emits particles at a rate of 3.7 X 1010 disintegrations per second (dps), or 2.2 X 1012 min-1 (dpm). Amounts that large are seldom used in experimentation, so subdivisions are convenient. The milli-curie (mCi, 2.2 X 109 min-1) and microcurie (yu,Ci, 2.2 X 106 min-1) are standard units for radioactive measurements (see Table 6.2). The radioactivity unit of the meter-kilogram-seconds (MKS) system is the becquerel (Bq). A becquerel, named in honor of Antoine Becquerel, who studied uranium radiation, represents one disintegration per second. The two systems of measurement are related by the definition 1 curie = 3.70 X 1010 becquerels. Since the becquerel is such a small unit, radioactive units are sometimes reported in MBq (mega, 106) or TBq (tera, 1012). Both unit systems are in common use today, and radioisotopes received through commercial sources are labeled in curies and bequerels. 

The definition of high-level waste in Clause (A) of NWPA given above follows the traditional, source-based description although, for the first time, the presence of fission products is mentioned explicitly. However, the definition remains qualitative because highly radioactive material and sufficient concentrations of fission products are not quantified, nor are the minimum concentrations of alpha-emitting transuranium radionuclides. 

Issues of dual regulation also arise in management and disposal of waste that contains NAEM and waste classified as hazardous under RCRA. This type of waste is subject to dual regulation essentially because the definition of hazardous waste developed by EPA under RCRA (EPA, 1980b) does not include NARM waste (Section 4.2.1.2). Waste that contains NARM can be regulated under RCRA only if it is specifically included in the definition of hazardous waste, even though the exemption of radioactive materials defined in AEA from regulation under RCRA does not apply to NARM. 

Hazardous chemical waste is defined in RCRA regulations as a solid waste that exhibits the characteristic of ignitability, corrosivity, reactivity, or toxicity, or is a specifically listed waste. The definition of hazardous waste specifically excludes radioactive material (source, special nuclear, or byproduct material) defined in AEA. 

In 1934, nuclear physics was young and the neutron had only just been discovered, yet the transuranium project was approached with a remarkable degree of confidence. The concepts from chemistry and nuclear physics that framed and guided the investigation were never seriously questioned, even though the synthesis and identification of new elements was, by definition, a leap into the unknown. Similarly, researchers were relatively unconcerned about the limitations of their small-scale experiments, even though the experiments themselves were notoriously difficult due to the tiny quantities of radioactive material. 

Standards for the control of residual radioactive materials from inactive uranium processing sites—definitions control of residual radioactive materials and their listed constituents EPA 2001k 40CFR192, Subpart A... 

See 173.389 (c) and 173.389 (o), for full-load shipments of radioactive materials meeting the definition of low specific activity when transported pursuant to 173.392 (b). 

For the purposes of transport, any material with a specific activity greater than 70 kBq/kg (0.002 M-Ci/g) must be declared as a radioactive material. Nevertheless, a material coming within that definition may be present in such small quantity or incorporated in another material to such an extent that its hazardous nature is very much reduced and it may be excepted from certain packing and labelling requirements (see schedule 1, 2, 3 or 4 as appropriate). IMO Class 7, 1.1.5... 

Radioactive material means any material having a specific activity greater than 70 Bq per gram (0.002 microcurie per gram) (see definition of specific activity ). US 173.403... 

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... 

With these definitions in mind, the following section presents selected parts of the current 10 CFR Part 20, which went into effect on January 1, 1994. Holders of NRC licenses must have formal programs to ensure that all programs covered by the regulations and all individuals working with radioactive materials now comply with the revised standard. 

For accidental releases, the HC3 radioactive material storage areas are administratively controlled to total radioactive inventories in each location to less than HC2 thresholds. Thus, by the definition of these thresholds in DOE-STD-1027-92, accidents in the radioactive material storage facilities would have the potential for only localized consequences. Also in accordance with the definition of the DOE-STD-1027-92 thresholds, accidental releases from the HCF have the potential only for significant on-site consequences. Thus, no release with the potential to cause significant environmental insult exists. 

By DOE-STD-1027 definition, the HCF radioactive material storage areas (RMSA), since they are limited to radiological material inventories less than Hazard Category 2 thresholds, do not, by themselves, have the potential for significant off-site consequences. However, the potential release of this inventory as a contributor to the overall release can be evaluated for a perspective of the overall risk. 

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