Water quality control in primary cooling system of crud concentration suppressed boiling water reactor. I Water chemistry experience in latest crud conentration suppressed BWR.

Abstract

The No. 2 Unit of Fukushima-Daini Nuclear Power Plant (2F-2; I ,1 00 MWe) was commercially operated for 10,320 effective full power hours (EFPH) as its first fuel cycle. The basic design concept of the 2F-2 incorporated the following two features : (1) Application of procedures for reducing shutdown dose rate based on the Japanese Improvement and Standardization Program (2) Low crud generation to minimize radioactive waste by careful material selection for the primary system. Thus, it was possible to keep the average Fe concentration in the condensate water at less than 6 ppb during the first fuel cycle. As a result of this low value, the average life of powdered resin precoated prefilters was extended to about a month, and the average chemical regeneration period of the deep bed demineralizers was extended to more than one year. The water chemistry of the 2F-2 was characterized by low 6°C o and high 58 Co radioactivities in the reactor water, which resulted in a low shutdown dose rate determined mainly by 58 Co depositing on the primary piping. For example, average dose rate around the primary piping just after reactor shutdown was about 70 mR/h, about 7 5% of which was from 58 Co depositing on the pipe inner surfaces. The contribution of 6°C o was about 25%.

Improvements of Water Chemistry for Moderating Environmental Impacts of BWR Plants.

“…(8) means that increasing 6oCo radioactivity is not explained only by the change in the BJ load factor. The effects of pH change should also be considered.…”

Improvements of Water Chemistry for Moderating Environmental Impacts of BWR Plants

“…Cobalt-60 radioactivities calibrated by using the relationship between the relative crud deposition coefficient and the BJ fuel load factor, RBJ, are exprcssed as Eq. (8) with a deviation Rz of 0.10. RBJ = 1.92 -0 .…”