Deaeration practices in Swedish BWRs

The control of the concentration of dissolved oxygen in the reactor water during pre-nuclear hot test and before nuclear start-up has been a routine operation with the Swedish BWRs for almost ten years since the first test runs of the first Swedish BWR. During cold shut down the primary system is blanketed with nitrogen. During the yearly refuelling outage the reactor water is saturated with air. Before the start of nuclear heating of the reactor the oxygen is stripped of the ractor water by blowing nitrogen gas through the RPV. The Swedish BWRs have operated since the first start-up with oxygen addition to the feed water. In 1979 a chemical deaeration technique was successfully demonstrated in the 570 MWe Oskarshamn 2 BWR. The control of oxygen concentration of the primary water by addition of hydrogen to the coolant appears to be able to eliminate BWR IGSCC