EFFECTS OF HYDROGEN WATER CHEMISTRY ON RADIATION-FIELD BUILDUP IN BWRS

A number of boiling water reactor (BWR) plants worldwide are currently operating under hydrogen water chemistry (HWC). Ln some reactors, whe n switching from normal water chemistry (NWC) to HWC, an increase in t he recirculation piping dose rates has been observed. Understanding th e key factors which affect the dose rate increase is the subject of ou r current investigation. Laboratory experiments have been conducted un der control chemistry conditions to examine the rates of Co-60 deposit ion and the characteristic of oxide films formed on stainless steel su rfaces. The activity buildup data obtained from two operating BWRs are carefully reviewed and discussed in this paper. Based on both laborat ory and reactor data, a plausible mechanism of enhanced activity build up under HWC conditions is hypothesized.