Radiological hazard

DOE sites not only are subject to radiological hazards, but also have the typical physical, chemical, and biological hazards associated with other sites. Although your site may seem unlikely to have radiological hazards, they can be found in more places than you might believe. Eor example, if your site manufactures chemicals or other items, or generates electricity, it likely has some form of radiological hazards. 

Unlike many chemical hazards, radiological hazards can be easy to detect with highly sensitive, direct reading instruments. Radiological control personnel conduct surveys and post warning signs. 

The important aspect is to know how to control or limit your exposure to radiological hazards. Some of the solutions can be summarized as follows  

Anyone working with different types of radioactive material should know the conditions when various materials may be present. The following provides some additional guidance as to where radioactive materials may be present  

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Because of the high rate of emission of alpha particles and the element being specifically absorbed on bone the surface and collected in the liver, plutonium, as well as all of the other transuranium elements except neptunium, are radiological poisons and must be handled with very special equipment and precautions. Plutonium is a very dangerous radiological hazard. Precautions must also be taken to prevent the unintentional formulation of a critical mass. Plutonium in liquid solution is more likely to become critical than solid plutonium. The shape of the mass must also be considered where criticality is concerned. 

The radiological hazard of tritium to operating personnel and the general population is controlled by limiting the rates of exposure and release of material. Maximum permissible concentrations (MPC) of radionucHdes were specified in 1959 by the International Commission on Radiological Protection (79). For purposes of control all tritium is assumed to be tritiated water, the most readily assimilated form. The MPC of tritium ia breathing air (continuous exposure for 40 h/wk) is specified as 185 kBq/mL (5 p.Ci/mL) and the MPC for tritium in drinking water is set at 3.7 GBq/mL (0.1 Ci/mL) (79). The maximum permitted body burden is 37 MBq (one millicurie). Whenever bioassay indicates this value has been exceeded, the individual is withdrawn from further work with tritium until the level of tritium is reduced. 

Designation of restricted areas, e.g. containing flammable materials, eye protection zones, hearing protection zones, radiological hazards, microbiological hazards Ensuring freedom from obstruction of roads, stairs, gangways, escape routes Control of vehicles... 

Observing the partner for signs of adverse exposure to chemical, physical, or radiological hazards... 

Most of the radioactive isotopes of cerium have very short physical half-lives and do not normally represent a radiological hazard to humans. Only the three longer-lived isotopes, 141Ce, l3Ce, and H4Ce,... 

Under biological conditions, the thermodynamic end-point (the ultimately most stable form of the element) is perrhenate, which is rapidly excreted by the kidneys. This is in contrast to, for example, 13II and 90Y, which thermodynamically tend towards, respectively 1 (which accumulates in thyroid) and solvated Y3+ (which accumulates in skeleton) each of these constitutes a radiological hazard to nontarget tissues. 

Some alarm systems are manually operated others use sensors that automatically trigger the alarms. Smoke alarms installed in residences are examples of automatic alarms. A number of alarm systems on the market today will also sound automatically if a radiological hazard exceeds a specified threshold. Automatic radiation alarm systems provide a number of advantages over manually operated alarms ... 

Radiation Authority For radioactive materials, the Radiation Authority is usually a state agency or state designated official. The responsibilities of this authority include evaluating radiological hazard conditions during normal operations and during emergencies. 

A D—T fusion reactor is expected to have a tritium inventory of a few kilograms. Tritium is a relatively short-lived (12.36 year half-life) and benign (beta emitter) radioactive material, and represents a radiological hazard 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. 

Exempt waste would be defined as waste that contains such low concentrations of radionuclides that it could be exempted from regulatory control as radioactive material because the radiological hazards associated with disposal of the waste would be negligible. The basis for defining exempt radioactive waste recommended by IAEA is a limit on annual dose to individuals from waste disposal of 10 xSv (see Section 4.1.3.2). 

Accurate estimates of the accumulation of tritium on the surface and in the bulk of the materials of the various PFCs of ITER and the degree of tritium permeation to the coolant are very important for determining the tritium supply requirements, for assessing the radiological hazards from routine operation and from potential accidents, and for decisions regarding the de-tritiation system. 

Use risk assessment of potential biological, chemical, or radiological hazards in the community to determine roles and responsibilities of those involved in public health BT response. 

There has been significant public concern regarding the use of DU by the military, and it has been hypothesized that DU may be a cause of Gulf War Syndrome. The public concern also stems from the lack of awareness regarding the specific physical chemistry and hazards of DU, and the belief that DU is still a form of uranium and therefore radiologically hazardous. These concerns have given rise to the belief that DU may be used as a weapon of mass destruction in the form of a dirty bomb, or as an agent of bioterrorism. 

Although natural uranium has a low specific-activity of 0.67 pCi/g (25,000 Bq/g) and depleted uranium has even less (0.36 pCi/g) (10 CFR 20 Wrenn et al. 1987), it is reasonable to believe that uranium, such as highly enriched uranium with its high specific activity, may present a radiological hazard, especially in cases of human exposure (Kirk 1980 USNRC 1989). Three accidental exposure reports and health data from several years of follow-up studies are available (Kathren and Moore 1986 USNRC 1986 Zhao and... 

Uranium is unusual among the elements because it presents both chemical and radiological hazards. For soluble uranium, with an U enrichment no greater than 5%, limits on intakes and air concentrations for radiation workers are based on the chemical toxicity of uranium since it is more limiting than the radiological hazard. For this case, the USNRC s limit for a 40-hour workweek is 0.2 mg uranium per cubic meter of air average (USNRC 1993f). 

In contrast, the chemical toxicity of uranium is more important than its radiological hazard. In body fluids, uranium is present as soluble U(VI) species and is rapidly eliminated from the body (60% within 24 h Goyer and Clarkson (2001)). It is rapidly absorbed from the gastrointestinal tract and moves quickly through the body. The uranyl carbonate complex in plasma is filtered out by the kidney glomerulus, the bicarbonate is reabsorbed by the proximule tubules, and the liberated uranyl ion is concentrated in the tubular cells. This produces systemic toxicity in the form of acute renal damage and renal failure. 

APPLICATION OF THE RADIOLOGICAL HAZARD POTENTIAL (RHP) TO RADIONUCLIDES IN MAGNOX REACTOR DECOMMISSIONING... 

The paper considers how the updated metric, named Radiological Hazard Potential (RHP), can be summated for the radioactive waste streams on a particular site and used to help set priorities for future waste management activities. Uncertainties in RHP values may be utilised to prioritise further sampling and radio-analytical measurements. The paper outlines the difficulties in dealing with hazards posed by non-radioactive materials, and some cautionary advice is given on the correct application of the RHP, particularly in avoiding its use as the sole criterion for establishing work priorities. 

Since the formation of the Nuclear Decommissioning Authority (NDA) there has been an emphasis on a demonstrable process for prioritisation of remediation work on UK decommissioning sites. As part of this process, the HI has now been re-named the Radiological Hazard Potential (RHP) and is one of five metrics which are combined numerically to produce a prioritisation metric, the Safety and Environmental Detriment (SED), see below. This paper relates only to the RHP. It is a quantitative measure of the potential for a material or plant item to cause harm, but does not address the risk of that harm occurring and has universal application irrespective of facility type. 

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