Exposure minimization radioactive materials

The substantial research eflforts on radioactive materials provided the information needed to establish stringent standards and control procedures that were effective in minimizing disease from occupational and environmental exposures to radioactive materials. Unfortunately, the catastrophic accident that occurred at the Chernobyl nuclear power station in 1986 has left an unfortunate legacy of radioactive contamination of the environment and associated increased potential for radiation-induced disease. The exact influence of this accident and of the radioactive contamination near Russian facilities associated with the nuclear weapons program of the U.S.S.R. will not be known for many decades. 

ALARA principle time, distance, and shielding. We should minimize our time working with radioactive materials, maximize the distance between us and the source of radiation, and use proper shielding to minimize our exposure. Finally, we must make sure that we understand and follow all the facility procedures and regulations regarding the use of radioactive materials so that our safety and that of our patients are assured. 

The transport of plutonium wastes to the transuranic and high-level repositories will represent a major increase in the quantities of radioactive materials shipped therefore an extensive demographic study has been made to examine potential exposures of the public and to select routes to minimize such exposure.45,46... 

Every containeroflicensedmaterialmustbeara clear, durable label bearing eitherCAUTION or DANGER, RADIOACTIVE MATERIAL. The label must also provide additional information, such as the radionuclide in the container, theamountpresent,thedateon which the activity was estimated, radiation levels, and the kinds of materials in order for individuals to determine the level of precautions needed to minimize exposures. The labels on empty, uncontaminated containers intended for disposal must be removed or defaced before disposal. There are exceptions to these labeling requirements, but most containers in use in a facility should be labeled. 

As with all laboratory work, protection of the worker against the hazard consists of good facility design, operation, and monitoring, as well as good work practices on the part of the worker. The ALARA (as low as reasonably achievable) exposure principle is central to both levels of protection. The amount of radiation or radioactive material used should be minimized. Exposures should be minimized by shielding radiation sources and workers and visitors and by use of emergency alarm and evacuation procedures. Physical distance between personnel and radiation sources should be maximized, and whenever possible, robotic or other remote operations should be used to reduce exposure of personnel. 

Occupationally exposed individuals are commonly known as "rad workers" and the training courses one takes to become a rad worker are usually referred to as "rad worker I" and "rad worker II" depending on the level of training provided. To be considered an occupationally exposed individual, a worker s job duties must involve exposure to radiation or a radioactive material. They must also be trained as required by 10 CFR 19.12 on how to properly handle radioactive material or work in areas where radiation exposure is possible and the proper precautions and procedures to follow. Because risks are involved, it is necessary that those exposed be knowledgeable about those risks and, more importantly, know how to minimize them to perform their jobs in a safe and effective maimer. Dose limits for occupational workers apply for all occupational dose received in a given year, even if it was from multiple employers. 

All individuals working in or frequenting any portion of a radiation area shall be informed of the occurrence of radioactive materials or of radiation in such portions of the radiation area shall be instructed in the safety problems associated with exposure to such materials or radiation and in precautions or devices to minimize exposure shall be instructed in the applicable provisions of this section for the protection of employees from exposure to radiation or radioactive materials and shall be advised of reports of radiation exposure which employees may request pursuant to the regulations In this section. 

To achieve the Safety Objectives, measures need to be taken to control radiation exposure in all operational states to levels as low as reasonably achievable and to minimize the likelihood of an accident that might lead to the loss of normal control of the source of radiation. Nevertheless, accidents can happen. Measures are therefore required to ensure that any radiological consequences are mitigated. Such measures include on-site accident management procedures and off-site intervention measures in order to mitigate radiation exposure after an accident has occurred. The greater the potential hazard from an uncontrolled release of radioactive material, the lower the likelihood must be of its occurrence. 

Non-radioactive components or services such as cooling water or purge air services should be located away from process equipment containing radioactive materials or outside of the shielded areas, to minimize radiation exposure to operators or maintenance personnel. 

Exposure of site personnel should be reduced by minimizing the possible amount of radioactive material in plant components. Traps and rough surfaces where radioactive particulates could accumulate should be avoided as far as practicable. 

The Chernobyl new safe confinement (NSC) will shield the sarcophagus, or shelter, that was constracted soon after the nuelear accident in 1986 to contain the deadly radioactive materials in damaged Unit 4. Specifically, the NSC is designed to keep radioactive dust in and rain out and to facilitate the deconstraction of the sarcophagus and Unit 4. The NSC is intended to minimize occupational exposure for at least 100 years, with the expectation that improved storage or disposal methods will be available within that time. 

The plant layout and procedures shall provide for the control of access to radiation areas and areas of potential contamination, and for minimizing contamination from the movement of radioactive materials and personnel within the plant. The plant layout shall provide for efficient operation, inspection, maintenance and replacement as necessary to minimize radiation exposure. 

A. 1222. In the description of the design considerations for the facility and equipment it shall be demonstrated that external and internal radiation exposures of facility personnel and the general public are based on the radiation protection policy described in para. A. 1203. It shall be described how the design philosophy reduces the exposure of personnel, minimizes the undesirable production of radioactive material, reduces the need and the time spent for maintenance and operational activities with the possibility of internal or external exposure, and keeps the releases of radioactive material to the environment as low as reasonably achievable. 

Isolation of radioactive wastes for long periods to allow adequate decay is sought by the use of multiple barriers. These include the waste form itself, the primary containers made of resistant materials, overpacks as secondary layers, buffer materials, concrete vaults, and finally the host rock or sod. Barriers limit water access to the waste and minimize contamination of water suppHes. The length of time wastes must remain secure is dependent on the regulatory limit of the maximum radiation exposure of individuals in the vicinity of the disposal site. 

Radon (Rn-222) is an odorless and colorless natural radioactive gas. It is produced during the radioactive decay of radium-226, itself a decay product of uranium-238 found in many types of crustal materials, that is, rocks and soils. Rn-222 has a short half-life (3.8 days) and decays into a series of solid particulate products, known as radon progeny or radon daughters, all of which have even shorter half-lives ( 30 min or less). Other isotopes of radon also occur naturally, but due to differences in half-life and dosimetry their health significance is minimal compared to that from exposure to Rn-222. 

During its lifetime, a fusion reactor presents little radiation hazard. The internal structure, particularly the vacuum containment vessel and the heat exchanger, will be subject to intense neutron bombardment. The neutrons will convert some of the elements of the structure into long-lived radioactive isotopes. Selecting construction materials that do not easily become activated can minimize radioisotope production. No material is entirely resistant to neutron activation, thus the decommissioning of a fusion reactor will require the handling and disposal of potentially hazardous radioactive isotopes. Because of the lack of uranium, plutonium, and fission products, the total radiation exposure hazard from the decommissioned fusion reactor is 10,000 to 1,000,000 less than from a decommissioned fission reactor. 

Technical Safety Requirements shall define the operating limits and surveillance requirements, the basis thereof, safety boundaries, and management or administrative controls necessary to protect the health and safety of the public and to minimize the potential risk to workers from the uncontrolled release of radioactive or other hazardous materials and from radiation exposure due to inadvertent criticality. 

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