Cobalt transport at the Vermont Yankee BWR

Technical Report · Thu May 01 04:00:00 EDT 1986

OSTI ID:5764875

Palino, G F; Hobart, R L; Wall, P S; Sawochka, S G; Gardner, J; Prystupa, M

The behavior of Co-59 (the precursor of Co-60) is of particular interest in BWRs since Co-60 has been shown to be primarily responsible for BWR shutdown radiation levels. To assist in understanding cobalt transport in the BWR, a cobalt solution was injected at the effluent of the condensate demineralized system and was transported to the primary system via the feedwater at the Vermont Yankee BWR. The quantity injected was equivalent to the amount transported during routine operation over approximately 7 days. Sample system modified to eliminate cobalt bearing alloys were demonstrated to provide valid process stream samples for cobalt. Cobalt injected at the effluent of the condensate demineralizers was retained in portions of the feedwater cycle for approximately six hours prior to the initial indication of an increase in cobalt transport to the primary system. This anomaly, which led to considerable difficulty in interpreting concentration variations observed during and subsequent to the injection, is attributed to chemi-sorption of cobalt on iron oxide coated surfaces of the condensate/feedwater system. A similar phenomenon also occurred in the primary system thus eliminating the possibility of establishing an absolute value for the primary system cobalt source strength. Nonetheless, it was possible to infer that cobalt transported to the reactor by the feedwater was the primary source of cobalt available for deposition on the fuel. 14 figs., 13 tabs.

• Research Organization: NWT Corp., San Jose, CA (USA); Vermont Yankee Nuclear Power Corp., Brattleboro (USA)
• OSTI ID: 5764875
• Report Number(s): EPRI-NP-4560; ON: TI86920262
• Country of Publication: United States
• Language: English

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