Surface decontamination deposition using

The cobalt deposition rate on new, replacement, or decontaminated recirculation piping surface has been reduced by pretreating the piping using an atmosphere of oxygenated wet steam to form an oxide film (25). Studies have been conducted for both PWRs and BWRs to reduce the cobalt content of materials used in the nuclear parts of the plants, particularly in hardened and wear surfaces where cobalt-base alloys ( 50% Co) are used (26). Some low cobalt materials have been developed however, the use of the materials is limited to replacement parts or new plants. 

It forms numerous salts, some of which are listed in Ref 4, p 466 L. It has been used for determination of about 40 metals and several anions (Ref 2) also used for decontamination of radioactive surfaces and removal of insol deposits of Ca Mg soaps (Ref 4). Its application in volumetric titrations is discussed in Ref 3. Accdg to Alrose Chem Co, PO Box 1294, Providence, RI, EDTA dissolves Ca oxalate and serves as a sequestrene. The term sequestration may be used for any instance in which an ion is prevented from exhibiting its usual props due to close combination with an added material (Ref 4, p 1013 L) ... 

Radioactivity transport in reactor coolant circuits involves both surface corrosion and deposition. Several XPS studies(8,9) of reactor boiler alloys have been reported which show the very strong effect of coolant chemistry on the films deposited. The chemistry of corrosion products precipitated on ZrO and Al O surfaces has been studied using XPS.ly More recently, chemical decontamination of radioactive boiler circuits has been assisted by XPS analysis of the surface-active decontaminating agent.(1 ) Surface oxidation in gas-cooled reactor circuits has also been investigated. AES has been used to follow the CC>2 oxidation of a chromium steel(H) and some pure metals. (12)... 

Confirmatory sampling is used by the decontamination crews to determine the effectiveness of the cleaning technique being employed. If a cleaned surface tests clean, the surface should be isolated from further airborne deposition. 

A variety of decontamination techniques are used. Key considerations in the selection of techniques include the appropriateness of wet or dry application, the nature of contaminant deposition, the depth of contamination, the sensitivity of the project to decontamination or surface damage, and the availability of ratios to monitor effectiveness. 

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