N_(2)气氛下氨水溶液γ辐射分解行为  

γ-Radiolysis of the aqueous ammonia solution saturated by N2

作　　者：郭子方 张扬 李一帆 林子健 刘春雨 林鹏 林铭章[1] GUO Zifang;ZHANG Yang;LI Yifan;LIN Zijian;LIU Chunyu;LIN Peng;LIN Mingzhang(School of Nuclear Science and Technology,University of Science and Technology of China,Hefei 230026,China;China Nuclear Power Technology Research Institute Co.,Ltd.,Shenzhen 518028,China)

机构地区：[1]中国科学技术大学核科学技术学院,合肥230026 [2]中广核研究院有限公司,深圳518028

出　　处：《辐射研究与辐射工艺学报》2024年第1期28-37,共10页Journal of Radiation Research and Radiation Processing

基　　金：国家自然科学基金“叶企孙”科学基金(U2241289)资助。

摘　　要：某些压水堆中使用氨及其分解产生的H_(2)抑制H_(2)O_(2)、O_(2)和·OH等氧化性物种的浓度,在保持一回路的还原性化学环境的同时调节冷却剂pH,以减轻结构材料的腐蚀。本工作为了研究脱氧氨水溶液在辐射场中的分解行为,针对其在γ场中的辐解过程进行了实验研究,重点考察了N_(2)压强、气相与液相体积之比和温度对氨水溶液辐解的影响,测定了剩余氨、H_(2)和氮氧化物(NO_(2)^(-)和NO_(3)^(-))的浓度及溶液的pH。结果表明:N_(2)压强(0.5~5.0 MPa)及气液体积比的变化未对氨的分解和氮氧化物的生成造成影响,吸收剂量为28.8 kGy时,辐解产生的氮氧化物浓度约为1 mg/L,但N_(2)压强和气液体积比的增加会显著降低H_(2)的浓度。温度由25℃升至200℃时,氨的分解过程将大幅放缓,吸收剂量为14.4 kGy时,30 mg/L氨水中氨的分解比例由26.5%降至8.4%,高温有利于抑制氨的分解速率,但同时导致NO_(2)^(-)和NO_(3)^(-)的浓度分别升高34和3倍左右。此外,本工作中还建立了含氨冷却剂的辐解模型并对其可靠性进行了验证,不同温度下实验数据与模型预测结果的最大相对误差仅为4.1%。随后利用该模型计算了不同初始浓度的含氨冷却剂辐解过程中剩余氨的浓度变化,结果表明较高的初始浓度有利于体系中氨的保持,连续辐照的情况下单独使用氨抑制氧化性物种时需要及时对其进行补充。In some reactors,ammonia and its radiolytic product(H_(2))are used to scavenge the oxidizing species(H_(2)O_(2),O_(2),and·OH).A reducing chemical environment is thus created and the pH of the coolant is regulated simultaneously.In the present study,the radiolytic behaviors of deoxygenated ammonia solution were studied in the γ-ray field.The impacts of N_(2) pressure,gas-liquid volume ratio,and temperature on deoxygenated ammonia solution radiolysis were investigated.The pH and the concentrations of residual ammonia,H_(2),and nitrogen oxides(NO_(2)^(-)and NO_(3)^(-))were analyzed.The results revealed that the variation of N_(2) pressure(0.5~5.0 MPa)and gas-liquid volume ratio had no influence on the concentrations of residual ammonia and nitrogen oxides.NO_(2)^(-)and NO_(3)^(-)concentrations were approximately 1 mg/L at room temperature when the absorbed dose was 28.8 kGy.However,the apparent concentration of H_(2) significantly decreased with the N_(2) pressure and gas-liquid volume ratio.The loss fraction of ammonia considerably declined from 26.5% to 8.4% when the temperature increased from 25 to 200℃,demonstrating that the radiolysis of ammonia was suppressed at the elevated temperature.However,the concentrations of NO_(2)^(-)and NO_(3)^(-)increased to 34 and 3 times,respectively,at 200℃ compared to those at 25℃.In addition,a radiolysis model of ammonia-containing coolant was established in the present study.The maximum relative error between experimental data and calculation results at any temperature was 4.1%.The model was thereafter used to calculate residual ammonia concentration with the absorbed dose under different initial ammonia concentrations.The results revealed that it was necessary to replenish ammonia regularly when using it alone to inhibit oxidizing species.

关 键 词：冷却剂 辐射分解 氨水 水化学 反应堆 

分 类 号：TL13[核科学技术—核能科学]