田湾核电站弱贯穿辐射调查与个人剂量监测

Weakly penetrating radiation and personal dose monitoring in Tianwan Nuclear Power Station

在田湾核电站两次大修换料期间,对1、2号机组开展了弱贯穿辐射调查,主要工作包括可能存在较高弱贯穿辐射风险场所的辐射剂量率监测、部分代表性工作人员受到的弱贯穿辐射剂量监测、防护用品的防护效果测试等。由弱贯穿辐射测量结果可知,田湾核电站各检修设备表面沉积的放射性核素基本一致,主要包含58Co、60Co、95Nb、95Zr、51Cr、124Sb、54Mn、110mAg、59Fe等,其伴随发射的β射线能量主要集中在600 keV以下。其中测得主泵剂量率比值H’(3)/H^*(10)最大值为2.08,H’(0.07)/H^*(10)最大值为34.9;蒸汽发生器H’(3)/H^*(10)最大值为2.58,H’(0.07)/H^*(10)最大值为10.7;堆本体H’(3)/H^*(10)最大值为1.25,H’(0.07)/H^*(10)最大值为26.4;主泵之外其他泵类设备H’(3)/H^*(10)最大值为3.80,H’(0.07)/H^*(10)最大值为55.6;阀门类设备H’(3)/H^*(10)最大值为1.15,H’(0.07)/H^*(10)最大值为4.18;其他物项H’(3)/H^*(10)最大值为1.53,H’(0.07)/H^*(10)最大值为2.16。检修人员弱贯穿剂量监测结果表明,Hp(0.07)/Hp(10)和Hp(3)/Hp(10)最大值分别为7.66和3.73,大修监测期间的个人剂量当量Hp(10)都在0.35 mSv以下,且这几次大修所有人员的个人剂量当量Hp(10)都小于2 mSv,由此可知Hp(0.07)和Hp(3)分别超过国家标准规定的个人剂量限值500 mSv/a及IAEA新限值20 mSv/a的可能性较小。根据弱贯穿测量结果,建议对主泵可抽取部件检修、反应堆水池清洁、KBA系统泵阀检修、放射性废物分拣等专项检修人员,开展眼晶体剂量和皮肤剂量监测。

During the two refueling outages of the Tianwan Nuclear Power Station,the investigation of weakly penetrating radiation of Units 1 and 2 was carried out,mainly including radiation dose rate monitoring at sites that may have a higher probability of weakly penetrating radiation,the weakly penetrating radiation dose monitoring received by some representative workers and the protective effect test of protective equipment. From the measurement results of weak penetrating radiation,the radionuclides deposited on the surface of the maintenance equipment of Tianwan nuclear power plant are basically the same,including 58Co,60Co,95Nb,95Zr,51Cr,124Sb,54Mn,110mAg,59Fe,etc. The β-ray energy is mainly concentrated below 600 keV. It is measured that the maximum value of H’(3)/H^*(10) is 2. 08 and H’(0. 07)/H^*(10) has a maximum value of 34. 9 for reactor coolant pump item;H’(3)/H^*(10) has a maximum value of 2. 58 and H’(0. 07)/H^*(10)has a maximum value of 10. 7 for the steam generator item;H’(3)/H^*(10) has a maximum value of 1. 25,’(0. 07)/H^*(10) has a maximum value of 26. 4 for the reactor item;The maximum value of H’(3)/H^*(10)is 3. 80 and H’(0. 07)/H^*(10) has a maximum value of 55. 6 for the other pumps item;H’(3)/H^*(10) has a maximum value of 1. 15 and the monitoring value of H’(0. 07)/H^*(10) is 4. 18 for the valves item. The maximum value of H’(3)/H^*(10) is 1. 53 and H’(0. 07)/H^*(10) has the maximum value of 2. 16 for the other items. The results of weakly penetration dose monitoring showed that the maximum values of Hp(0. 07)/Hp(10) and Hp(3)/Hp(10) are 7. 66 and 3. 73 respectively,and the personal dose equivalent Hp(10) during the overhaul monitoring period are all below 0. 35 mSv. In addition,the personal dose equivalent Hp(10) of the entire staff in these overhauls is less than 2 mSv. It indicates that Hp(0. 07) and Hp(3) are less likely to exceed the national standard personal dose limit of 500 mSv/a and the new IAEA limit of 20 mSv/a,respectively. It is suggested to carry out eye crystal dose and skin dose monitoring for special maintenance personnel such as reactor coolant pump maintenance, reactor pool cleaning, KBA system pumps and valves maintenance,radioactive waste sorting,etc.