The effect of radiation on carbon dioxide coolant

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The effects of radiation on carbon dioxide coolant are mainly reflected in the following aspects: it induces radiation-induced reactions. Under reactor irradiation conditions, CO2, which normally does not react significantly with graphite at temperatures below 600°C, becomes activated, causing the graphite to undergo gasification. The reaction rate is related to the intensity of nuclear radiation, the density of CO2, and the porosity of the graphite; the effect of temperature is not significant. It results in differences in material loss; the reaction rate in Magnox reactors is slow, with only 5% loss of graphite over a 20-year operational life ； However, in advanced gas-cooled reactors (AGR), due to the high pressure and high power density, the amount of graphite loss is significantly higher. Impact on operation and safety: This type of radiation-induced corrosion increases the maintenance costs of reactors and may also shorten the service life of equipment. Additionally, CO2 under irradiation produces a small amount of carbon-14, resulting in related emission issues. This can be improved by adding inhibitors; introducing a small amount of hydrogen or methane into the coolant can effectively suppress such radiation-induced corrosion reactions and reduce the rate of material loss.