The result of very small quantity of ETA injection program in Tomari Unit 1

In Tomari Nuclear Power Station, iron concentration reduction of feed water is quite important subject to maintain the integrity of Steam Generator (SG) heat transfer tubes. Water chemistry of BOP in Tomari is all volatile treatment (AVT) to adjust pH=9.3 in feed water as NH3 and 0.3ppm N2H4. In order to reduce iron concentration, two water chemical methodologies are applied internationally in commercial plants, namely high AVT and advanced amine treatment. Tomari has some copper bearing materials in BOP heat exchangers, therefore high AVT is not able to be applied without large scale replacement of copper bearing materials. Tomari flow full condensate water for Condensate Demineralizing polisher and furthermore has an environmental regulation of COD concentration in disposable waste water, therefore advanced amine treatments are restricted in the upper limit of amines concentration unless Condensate Demineralizing System (CDS) and disposal waste water treatment system are largely improved. Consequently, very small quantity of ETA injection to present AVT was the most effective for Tomari condition, so the injection of very small quantity of ETA program in Tomari Unit-1 was tested. The test resulted in 20-30% reduction effect of iron concentration in the secondary feed water system, especially 50% reduction in steam/water two phase flow at maximum. This paper reports the outline and prospect of ETA injection program in Tomari. (J.P.N.)