Chemical Connections decontamination using chemicals

Operations using perchloric acid for digestions or heated dissolutions should be performed in perchloric acid hoods that are specifically constructed for this purpose. Perchloric acid, being extremely reactive, can produce explosive perchlorates with metals that are touch- or shock-sensitive. Thus, the interior lining of these hoods must be constructed of nonreactive materials (such as stainless steel) with sealed seams to facilitate decontamination. These hoods are normally fitted with equipment for washing down the interior of the hood exhaust system after perchloric acid use to prevent the buildup of explosive perchlorate residues. The entire exhaust system must be independent of other exhaust systems connected to other chemical hoods. These hoods must be clearly labeled as perchloric acid work only. Anyone using perchloric acid should seek special training in these operations. 

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... 

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