低剂量氚相对生物效能的实验研究与建议

Experimental study and suggestions on the relative biological effectiveness of low-dose tritium

笔者从辐射防护的角度概述了核聚变燃料氚低剂量照射下的相对生物效能(RBE)的研究。选择指数递减剂量率和恒定剂量率2种氚照射方式, 观察研究以下生物学指标:卵母细胞和精母细胞的显性致死突变率, 显性骨骼突变率, 初级卵母细胞和精原细胞的存活率, 以及外周血淋巴细胞和胎肝嗜多染红细胞微核细胞率。计算2种氚照射方式下的RBE值, 并分析RBE的影响因素。结果显示, 在累积剂量为0.2、0.3、0.4、0.5、0.6 Gy/10 d的条件下, 指数递减剂量率和恒定剂量率2种氚照射方式下的RBE值为2.9~4.2。为了辐射防护的目的, 建议将低传能线密度(LET)辐射对生物群的RBE值设定为3.0~3.5。如果估计暴露于氚β粒子或其他低LET辐射或接近导出考虑参考水平下, 则可能需要采用较高的RBE值进行评估, 以更为准确地估计辐射的危险度。

Studies on the relative biological effectiveness(RBE)of tritium as nuclear fusion fuel under low-dose irradiation from the perspective of radiation protection were summarized.Two tritium irradiation methods,namely,exponentially decreasing dose rate and constant dose rate,were selected to observe and analyze the following biological indicators:dominant lethal mutation rate in oocytes and spermatocytes,dominant skeletal mutation rate,survival rate of primary oocytes and spermatogonia,and micronucleus cell rate in peripheral blood lymphocytes and polychromatic erythrocytes of fetal liver.The RBE under these two tritium irradiation methods was calculated,and the factors influencing the RBE were analyzed.Results showed that at cumulative doses of 0.2,0.3,0.4,0.5,and 0.6 Gy/10 d,the RBE under the tritium irradiation methods of exponentially decreasing dose rate and constant dose rate was 2.9-4.2.For radiation protection,the RBE of low-linear energy transfer(LET)radiation on the biome must be set to 3.0–3.5.In case of exposure to tritiumβparticles or other low-LET radiation or values close to the derived reference level,a high RBE may be required for an accurate estimation of the radiation risk.