Decontamination materials compatibility

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. 

Results from a study using live mustard agent showed that the dry wipe was able to adsorb the off-gassing mustard vapors better than the particulate activated carbon and M291 reactive adsorbent substrate. In addition, this wipe performed better in its material compatibility characteristics with strong acids and bases. Another study has proven that the dry decontamination wipe is capable of adsorbing vapors from organophosphorus compoimds like methyl parathion. " ... 

There is an abiding interest in reducing the concentrations of the chemicals in the decontamination solutions, not only to further improve materials compatibility but also to minimize the resulting volume of radioactive waste. To this end, a simple reduction in concentration alone is not sufficient, since such a measure... 

Other full-system decontaminations (e. g. of the Steam Generating Heavy Water Reactor) have been performed using the Rjrco reagent or the Lomi process with and without the NP pretreatment step. The results of these operations were satisfactory as regards decontamination factors and materials compatibility at the circuit surfaces, as well as at the fuel assemblies. 

The Cord process is especially suited for the decontamination of PWR and BWR full primary systems. Detailed investigations (Wille and Bertholdt, 1989) have shown optimum materials compatibility with the solvents to be applied. Calculations showed that using the volume control system of the plant and the connected auxiliary systems, the time required for one decontamination cycle depends on the capacity of the purification system at a purification rate of 15% of the primary loop volume per hour, 24 hours are required. Heating of the entire loop can be achieved by running the main coolant pumps. As the reagents used for the oxidation step are chemically reduced, no time is lost with ion exchange, and a purification step by ion exchange is required only at the end of the decontamination step. For the decontamination of Siemens PWR primary loops, no external equipment is required while the installed capacities in other PWRs and BWRs are... 

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 construction shall allow easy decontamination of surfaces. Compatibility of decontamination materials and the operating environments shall be considered for operational states and design basis accidents. 

During collection, storage, and transportation, use containers constructed of materials compatible with the treatment methods utilized. Ensure the use of burnable single-use containers for waste destined for incinerators. Containers destined for steam sterilizers should allow proper treatment of the waste. Decontaminate reusable containers after each use using only approved methods. Never reuse containers unless decontaminated and before use remove all medical waste labeling. 

Equipment meant to replace obsolete equipment is not always identical to the installed equipment so machining work may be necessary to make connections fit (e.g., the lift cylindeais for the bulk drain system at TOCDF). Sometimes a change in campaigns may lead to an unantidpaled incompatibility of materials. An example of this is the sump lining material at TOCDF that was designed for compatibility with decontamination fluids for GB, but was eroded by the different decontamination fluids used for VX. The sumps had to be relined with a suitable new material. 

Full-system decontaminations require a particularly extensive preparatory work. Compatibility of the materials to the reagents applied in the decontamination solutions is of highest significance when further operation of the plant is planned not only the materials present in the primary circuit have to be tested for corrosive attack, but those in the components of the nuclear auxiliary systems as well, which will be in contact with the solutions in the course of the decontamination procedure. Due to differences in the materials applied, such a test might only be applicable for the plants of a given manufacturer occasionally, a special composition of materials present in one individual plant has to be taken into account. Another... 

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