Radiation Chemistry of Nitric Acid Solutions.

Abstract

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New insight on the simultaneous H2and HNO2production in concentrated HNO3aqueous solutions under alpha radiation

“…As previously observed in α self-radiolysis, the formation of nitrite in HNO 3 is proportional to the absorbed dose. Kazanjian et al 89 observed an increase of nitrite, that reaches a maximum concentration in γ radiolysis for HNO 3 solutions with concentrations lower than 1 mol dm −3 while at concentrations higher than 1 mol dm −3 , the nitrite increase is linear. The authors suggest that a similar maximum concentration of nitrites for higher doses and β and α radiation, is not excluded.…”

“…Nitrite ions are produced indirectly via attack on nitrate ions by the water radiolysis primary species (reactions (13)–(31) ) or directly by ionizing radiation (reaction (9) ). Kazanjian et al 2 showed that the formation of HNO 2 in HNO 3 in solutions of concentrations higher than 1 mol dm −3 is a result of both direct and indirect action of ionizing radiation; Balcerzyk et al 35 showed that even in HNO 3 solutions of concentrations of 1 mol dm −3 , the direct effects of ionizing radiation have a non-negligible contribution to the formation of nitrate radicals or ions, which in turn can lead to formation of nitrite. Considering the acidity of the investigated solution and following its p K a value: p K a (HNO 2 /NO 2 − ) = 3.24 at 25 °C, 66 nitrite ions exist as nitrous acid.…”

“…The effect of radiation on solvent (HNO 3 ) extractions may result in decreased ligand concentrations, and accumulation of possibly dangerous degradation products. Among these, the most hazardous product is H 2 that can be formed during the radiolytic degradation of HNO 3 , 2–4 due to its flammability range, low ignition energy and high deflagration index 5,6 inside a canister. Due to the multi-component aspect of spent nuclear fuel, a multidirectional approach is needed, taking into account the alpha, beta and gamma radiation induced degradation.…”

Characterization of palladium species after γ-irradiation of a TBP–alkane–Pd(NO3)2system

“…Radiolysis of nitric acid primarily leads to the formation of HNO 2 ( ref. 23 and 70 ) and H 2 O 2 ( ref. 70 ) whereas radiolysis of TBP and TPH can generate many different degradation products such as alkenes, carbonyl compounds (R–CO–R′, R–CO–H), carboxylic acids (R–COOH), alcohols (R–OH), nitro compounds (R–NO 2 ) 23 and phosphorus compounds such as HBDP, H 2 MBP, H 3 PO 4 , etc.…”

Influence of Nitric Acid on the Helium Ion Radiolysis of Aqueous Butanal Oxime Solutions

“…The presence of nitric acid has also an impact on the yields of water radiolysis products especially (H 2 and H 2 O 2 ). Furthermore, nitrous acid (HNO 2 ), or its basic form, nitrite ion (NO 2 – ) are mainly formed under nitrate ion solutions radiolysis due to an interaction between the radicals formed by the radiolysis of water and those formed by the radiolysis of nitrate ions. − The first step of nitrous acid production is the formation of radical intermediates in neutral (eq ) or acidic media (eq ). …”