NITRITE FORMATION IN THE RADIOLYSIS OF AERATED AQUEOUS SOLUTIONS OF AMMONIA

摘要

Gamma irradiation of aerated aqueous solutions of ammonia leads to the formation of nitrite as a radiolytic product. Its yield increases with increasing concentration of NH_3 as well as O_2 . OH radicals react with NH_3 to give NH_2 radicals, which in the presence of O_2 form NH_2O_2 radicals. These radicals finally lead to the formation of nitrite. G(NO_2~-) decreases with increasing radiation dose due to secondary reactions. Its initial yield, however, is more than 1/2 G_(OH), while hydrogen peroxide yield is less than the expected value viz. G(H_2O_2) + 1/2 G(e_(aq)~-), indicating its participation in reactions with radiation produced free radicals. G(H_2) is 0.35 in aerated aqueous solutions of 10~(-3) mol dm~(-3) NH_3 and 0.23 in the absence of oxygen. Implications of these results to the use of NH_3 in primary coolant water of pressurized water nuclear power reactors of the VVER type are discussed.