Decontamination chemical methods

The surface-contaminated materials which, during plant operation, were located outside the neutron field represent the largest fraction by far of the spent materials even when a full-systems decontamination has been performed, residual contamination is still associated with these materials. In principle, they also have to be conditioned and finally disposed as radioactive waste. The same applies to components which were removed from the plant during a replacement action (such as PWR steam generator tube bundles or BWR recirculation piping). In order to further reduce the remaining contamination level, hard chemical decontamination methods can be applied, since materials compatibility of the solutions is not re-... 

The chemical and physical compatibility of decontamination solutions or other decontamination materials must be determined before use. Any decontamination method that permeates, degrades, damages, or otherwise impairs the functioning of the personal protective equipment (PPE) is incompatible with such PPE and should not be used. If a decontamination method does pose a direct health hazard, measures must be taken to protect both decontamination personnel and the workers being decontaminated. Figure 16.22 presents a decision aid for the evaluation of health and safety aspects of decontamination methods. 

WASTE DISPOSAL METHOD All decontaminated material should be collected, contained and chemically decontaminated or thermally decomposed in an EPA approved incinerator, which will filter or scrub toxic by-products from effluent air before discharge to the atmosphere. Any contaminated protective clothing should be decontaminated using HTH or bleach and analyzed to assure it is free of detectable contamination (3X) level. The clothing should then be sealed in plastic bags inside properly labeled drums and held for shipment back to the DA issue point. Decontamination of waste or excess material shall be accomplished in accordance with the procedures outlined above with the following exception ... 

Treatment—Patients should be decontaminated immediately prior to treatment using the chemical agent decontamination method presented in Section 7.3.2. No known antidote is available. 

EPA (2006). Sentinels Detection Methods and Chemical Decontamination Health Risk Key Components of EPA s Safe Building Program. US Environmental Protection Agency, Washington, DC. 

The ideal chemical separation method should be relatively simple, have few separation stages and should be time / cost effective. Itoh et al (2002) used a combined anion and cation exchange column method for the isolation of Ca from other alkaline earth metals. This 3 column separation involved 6 chemical separation techniques following two HF/HCIO4 digests. The decontamination factors for Eu and Co are quoted as >10. The final limit of detection for " Ca for this method was 8 Bq/g, based on a measurement by X-ray spectrometric determination. 

Military personnel may be questioned for guidance by local civilian authorities or may deal with supply shortages in the field. Knowledge of the U.S. doctrinal decontaminating solutions may not suffice in these situations, and awareness of alternative methods of decontamination will prove very beneficial. What decontamination method is used is not as important as how and when it is used. Chemical agents should be removed as quickly and completely as possible by the best means available. 

Yurow HW. Decontamination methods for HD, GB and VX A literature survey. Aberdeen Proving Ground, Md Army Armament Research and Development Command Chemical Systems Laboratory 1981. AD-B057349L. 

Gel carrier for vertical surfaces Surfactant-based Decontamination Solution Quaternary Ammonium Complex Decontaminant Chemical/UV decontamination method... 

A method of decontaminating alllaboratory wastes must be available, preferably within the laboratory (i.e., autoclave, chemical disinfection, incineration, or other approved decontamination method). 

Neutralization. Neutralization involves the elimination of a chemical s toxicity by applying another chemical that reacts with it, such as neutralizing an acid with an alkali. These reactions can produce heat, which is potentially as damaging as the original chemical. This method is almost never used on contaminated victims. This is more applicable to decontaminating environmental surfeces than victims. 

Methods discovery for decontamination concerns the research and development to identify what will neutralize or kill chemical or biological agents. Ideally, decontamination methods will be effective against a broad array of potential agents and pathogens. Also, it is desirable that methods will not be corrosive or otherwise destroy the functionality of materials and equipment being decontaminated. 

Later on, the process solutions contained comparatively high concentrations of organic acids (hard decontamination methods) the processes at that time were based on fixed, preset chemical and application parameters and special procedures for component and system decontamination. Today, most of the processes applied for operational decontamination use extremely low concentrations of chemicals (soft decontamination methods) and are applied in several brief cycles, possibly including variations in the chemical composition of the decontamination solution. In doing so, it became possible to adapt the decontamination process to the conditions and requirements of the system or component to be decontaminated. Several successive short decontamination cycles make better use of the allocated time frame, since an additional cycle can always be added. Important benefits of these new decontamination technologies are improved decontamination factors, shorter time requirements, less radioactive waste and a virtually zero hazard to the materials. 

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