Behavior of Nitrogen Compounds in Radiation Field and Nuclear Reactor Systems

Abstract

Formation of nitrogen compounds in N,-H 2 0 systems under radiation was studied. A reaction scheme with 24 species and 73 reactions was proposed. Two trigger reactions for nitrogen atom generation: N, ~ 2N (o-value of 1.6 pmol per 1 kJ absorbed energy in N 2 molecules), and N2+H20*-NH 2 +NO (k=3.0 x 10 9 s-at 298 K with activation energy of 34.4 kJ/mol) were included. Calculated results with the reaction scheme agreed within an error factor of two with ammonium formation rates from an aqueous solution with dissolved nitrogen and hydrogen gasses under r-irradiation at temperatures of 288-473 K. The reaction scheme was also verified with BWR plant observations on nitric acid formation from in-leaked air under hydrogen water chemistry and ammonium injection tests.

Nitrogen compounds' formation in aqueous solutions under high ionizing radiation: An overview

“…In addition to NO and NH 2 in reaction (2), the formation of nitrogen atom by irradiation has also been proposed N 2* 2N (Ibe et al, 1989), and the generation of N-atom is explained as…”

“…However, the index of water chemistry related to HWC reportedly vary from plant to plant, which may be partly attributed to specific impurities present in the water used (Ibe et al, 1989). Nitric acid and NH þ 4 formed through radiolytic reactions from continuous air in-leaked or airingress from the main steam condenser, are among such impurities (Ibe et al, 1989). Nitrous acid is reported to form in moist air radiolysis (Reed, 1991;Baulch et al, 1973), and its high concentration affects the oxygen responses.…”

“…According to them the formation of nitrogen oxides takes place exclusively in the gas phase as indicated by the increase in nitrate ion yield with increasing gas to liquid volume ratio. Dimitriev (1963) has proposed a direct reaction of N 2 with d OH radicals (reaction (1)) whereas Ibe et al (1989) have proposed a reaction of N 2 with excited water molecules (reaction (2)) for nitrate formation N 2 + d OH-NO+NH (Dimitriev, 1963) (1) N 2 +H 2 O n -NO+NH 2 (Ibe et al, 1989) (2) However, these reactions predict an equal proportion of -N-H type (e.g. NH 3 ) and -N-O type (e.g.…”

“…of nuclear reactors (boiling water reactors (BWR)/PWR/pressurized heavy water reactors (PHWR)) has been one of the most important concerns in the corrosion engineering of structural materials (Cowan et al, 1988), to achieve long reactors' life. Hydrogen-water chemistry (HWC) has been commonly applied to BWR primary coolants, to suppress oxygen and thus mitigate susceptibility for stress corrosion cracking of structural materials (Ibe et al, 1989). However, the index of water chemistry related to HWC reportedly vary from plant to plant, which may be partly attributed to specific impurities present in the water used (Ibe et al, 1989).…”

“…Hydrogen-water chemistry (HWC) has been commonly applied to BWR primary coolants, to suppress oxygen and thus mitigate susceptibility for stress corrosion cracking of structural materials (Ibe et al, 1989). However, the index of water chemistry related to HWC reportedly vary from plant to plant, which may be partly attributed to specific impurities present in the water used (Ibe et al, 1989). Nitric acid and NH þ 4 formed through radiolytic reactions from continuous air in-leaked or airingress from the main steam condenser, are among such impurities (Ibe et al, 1989).…”