严重事故安全壳废液中核素活度计算

福岛事故后,放射性废液的处理受到了高度关注。严重事故后安全壳废液中的核素活度分析是废液处理的前提。根据严重事故后安全壳废液中放射性核素的来源及消减机理,建立了AP1000严重事故安全壳废液中核素活度计算模型,研究安全壳废液中放射性核素活度的变化。结果表明：在堆芯核素向安全壳释放阶段,废液中各组核素活度逐渐增大,随后除镧组核素外,其他各组核素活度随时间逐渐减小,碘总活度降低最快,铯组总活度降低最慢；在事故初期,碘是废液中的主要核素,其次是铯；铯组核素占总活度的份额先减小后增大,而其他组核素占总活度的份额先增大后减小。¹³⁴Cs、¹³⁷Cs、⁸⁹Sr、⁹⁰Sr、¹²⁷Te^m、¹⁰³Ru、¹⁰⁶Ru、¹⁴⁴Ce、²⁴¹Pu、⁹⁰Y、⁹¹Y、⁹⁵Nb、⁹⁵Zr衰减很慢,是放射性废液的重要组成成分。#$NL关键词 严重事故；安全壳；废液；核素；放射性活度#$NL中图分类号 TL732； 文献标志码 A

Calculation on Nuclide Radioactivity of Liquid Waste in Containment under Severe Accident

After Fukushima accident, the treatment of radioactive liquid waste has been highly concerned. The analysis of nuclide activity in containment liquid waste after severe accident is the premise of the liquid waste treatment. The source and reduction mechanism of nuclides in containment liquid waste after severe accident were analyzed. The calculation model for the nuclide radioactivity was established. The parameters of AP1000 were used for calculation on the radioactivity in containment liquid waste, and the radioactivity change of main nuclides in the containment liquid waste was studied. The results show that during the release of nuclides from core into containment, the radioactivity of each group nuclides in the containment liquid waste gradually increase, and then with the exception of the lanthanum group nuclides, the radioactivity of other group nuclides gradually decrease with time. The total iodine radioactivity decreases the fastest, and the total cesium radioactivity decreases the slowest. In the early stage of the severe accident, iodine is the main nuclide in the liquid waste, followed by the cesium group nuclides. The proportion of cesium activity in the total activity decreases first and then increases, while that of other groups increase first and then decrease. It is concluded that ¹³⁴Cs, ¹³⁷Cs, ⁸⁹Sr, ⁹⁰Sr, ¹²⁷Te^m, ¹⁰³Ru, ¹⁰⁶Ru, ¹⁴⁴Ce, ²⁴¹Pu, ⁹⁰Y, ⁹¹Y, ⁹⁵Nb and ⁹⁵Zr decay very slowly, which are the important components of the radioactive liquid waste.