Standard versus hydrazine water chemistry in VVER-440s: a score draw

Studies of VVER-440 reactor water chemistry have found that there is no significant difference between new VVER units using hydrazine water chemistry and those with standard water chemistry. The level of Co-60 activity was found to depend on the level of cobalt impurities in in-core and steam generator materials. A short hydrazine experiment at Bohunice 3 (finished in the second third of cycle 2) produced no significant results since only the level of Co-58 activity on the steam generator tube surfaces appeared to be affected. (author)