METHOD FOR DECONTAMINATING INNER SURFACES OF NUCLEAR REACTOR EQUIPMENT Russian patent published in 1999 - IPC

FIELD: nuclear power engineering; removal of corrosion products from inner surfaces of reactor circuits, such as multiple forced circulating circuits of boiling reactors. SUBSTANCE: method involves decontaminating inner surfaced by their treatment with oxalic acid base solutions in two stages; novelty is that during second stage it is proposed to conduct treatment with thinned oxalic acid solution containing nitrite-ion which should be introduced in this solution in the form of nitrite, concentration of components being as follows, g/l: oxalic acid - 0.01- 0.1; nitrite - 0.015-0.1; decontamination is proposed to be conducted for 3-5 h at 85-100 C. Adding nitrite-ions provides for eliminating secondary deposition of ferrous iron oxalate at the time forming oxide film on steel surfaces protecting metal from corrosion; this ensures 2- 2.5 times lower corrosion loss in the course of decontamination. EFFECT: improved in-service corrosion resistance of steel. 2 cl, 4 dwg, 1 tbl