The operating experience of the ABWR water chemistry

The first Advanced Boiling Water Reactor (ABWR), Unit no.6 of the Kashiwazaki Kariwa Nuclear Power Station (K6), have started the commercial operation since November 1996. The first cycle was successfully operated and after the fuel outage of 55 days the second operation cycle is started. Unit no.7 (K7) that is the twin plant of Unit no.6 is also in operation since July 1997. The ABWR has 1356MWe electric output. In many special features of ABWR, the internal recirc pumps (RIP, reactor internal pump), moisture separator re-heaters, and heater drain pump up systems are the special subjects from the viewpoint of the water chemistry management. The primary system materials are made of SUS316L and lower Co content materials for the SCC (Stress Corrosion Cracking) mitigation and the dose rate reduction. In the Water chemistry management extremely lower iron crud control in the feed water is tried for the K6 to reduce the dose rate in the plant. While, for the K7 Improved Ni/Fe control is implemented. In this paper the experience of water chemistry management of the ABWRs are introduced. (J.P.N.)