硝酸对N,N-二甲基羟胺γ-辐解及液态辐解产物的影响

N,N-二甲基羟胺(DMHA)是用于动力堆乏燃料后处理U与Pu和Np分离的新型无盐还原剂, 本文研究了硝酸对DMHA γ-辐解及液态辐解产物的影响. 研究结果表明: 在U、Pu分离循环和Pu纯化循环的辐照剂量下, 在0.3-1.0 mol·L^-1的硝酸溶液中, 0.1 和0.5 mol·L^-1 DMHA具有较好的辐照稳定性. 当吸收剂量为5-25kGy时, DMHA硝酸溶液的液态辐解产物主要有单甲基羟胺、甲醛、甲酸和亚硝酸. 有机物的浓度远远高于亚硝酸浓度, 且随着剂量和硝酸浓度的增加而增大. 对于相同的硝酸浓度和剂量, 0.1 mol·L^-1 DMHA辐解产生的一甲基羟胺的浓度高于0.5 mol·L^-1 DMHA, 但前者辐解产生的甲醛浓度低于后者; 当硝酸浓度较高时, 0.1 mol·L^-1 DMHA辐解产生的甲酸浓度高于0.5 mol·L^-1 DMHA. 亚硝酸浓度与硝酸浓度及剂量的关系取决于起始DMHA和硝酸浓度.

Effect of HNO3 on the γ Radiolysis and Radiolytic Liquid Products of N,N-Dimethylhydroxylamine

N,N-dimethylhydroxylamine (DMHA) is a novel salt-free reductant used for the separation of U from Pu and Np in the reprocessing of spent fuel. We investigated the effect of HNO₃ on the radiolysis of DMHA and its radiolytic liquid product. Results show that 0.1 and 0.5 mol·L^-1 DMHA containing 0.3-1.0 mol· L^-1 HNO₃ have good radiation stability at a reasonable dose level during the U/Pu separation cycle and the Pu purification cycle. For 5-25 kGy the main radiolytic liquid products are N-methyl hydroxylamine, HCHO, HCOOH, and HNO₂. The concentration of these organic compounds is much higher than that of HNO₂ and increases with both HNO₃ concentration and absorbed dose. At the same HNO₃ concentration and dose, the concentration of N-methyl hydroxylamine in irradiated 0.1 mol·L^-1 DMHA-HNO₃ is higher than that in irradiated 0.5 mol·L^-1 DMHA-HNO₃. However, the HCHO concentration in 0.1 mol·L^-1 DMHA-HNO₃ is lower than that in 0.5 mol·L^-1 DMHA-HNO₃. The HCOOH concentration in 0.1 mol·L^-1 DMHA-HNO₃ is higher than that in 0.5 mol·L^-1 DMHA-HNO₃ at higher HNO₃ concentrations. The relationship of HNO₂ concentration with HNO₃ concentration and dose depends on the original DMHA and HNO₃ concentrations.