Method to control n-16 radiation levels in steam phase bwrs

Abstract

In a boiling water reactor nuclear plant, hydrogen is injected into the feed water to neutralize radiolysis which causes stress corrosion in stainless steel components. It has been discovered that by inhibiting volatile ammonia, and other gaseous nitrogen compounds from leaving the liquid phase portions of the plant to the steam phase portions of the plant, radiation is reduced to acceptable levels. Formation of ammonia is inhibited chemically, by altering the reaction paths for volatile nitrogen species with trace additives in the parts per billion range, suitable additives include nitrous oxide, copper, zinc, carbon dioxide, and other components. It has also been found that by manipulating the pH, the formation of the voltage nitrogen compounds, especially ammonia, is decreased. Similarly, by physically altering plant operating conditions to reduce sparging or scrubbing of the gases from areas of high radiation, confinement of the N-16 within the liquid phase of the plant within the reactor vessel occurs. It is further found that by decreasing the total hydrogen concentration in the core region, the N-16 volatility can be limited. This includes alternate hydrogen injection points and enhancement of the hydrogen-oxygen recombination reaction by e.g., catalysis by radiation or by surfaces. The possibility of increasing the N-16 holdup time in the steam phase is also considered. Finally, the concept of operating at a higher electrochemical potential which requires a lower hydrogen concentration and hence less N-16 converted to the volatile form is also described.