Mechanism Study and Control of 41Ar Source Term in EPR Unit Coolant
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摘要: 为控制欧洲压水反应堆（EPR）冷却剂中的41Ar辐射源项，本研究首次构建了压水堆冷却剂中41Ar的源项输运模型，揭示了在不同工况下41Ar比活度变化的规律。通过模型分析发现了某机组冷却剂中41Ar比活度异常情况，并首次探测到EPR加氢站气-液分离器内形成了稳定的气态辐射热点。利用模型追溯了外界空气携带40Ar进入冷却剂的具体途径，并据此采取措施有效控制了41Ar的辐射源项，降低了机组的辐射风险。
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关键词:
- 欧洲压水反应堆（EPR） /
- 反应堆活化 /
- 源项控制 /
- 辐射防护 /
- 41Ar
Abstract: In order to control the Argon-41 (41Ar) radiation source term in European Pressurized Reactor (EPR) coolant, this research pioneers the development of a transport model for 41Ar in EPR coolant and elucidates the pattern of 41Ar specific activity variation under different conditions. Through the model analysis, it is found that the specific activity of 41Ar in the coolant of a unit is abnormal, and it is the first time to detect the formation of a stable gaseous radiation hotspot within the gas-liquid separator of the EPR's hydrogen refueling station. The model is used to trace the specific path that the environmental air carries 40Ar into the coolant, and measures are taken to effectively control the radiation source term of 41Ar and reduce the radiation risk of the unit. -
图 1 压水堆冷却剂中41Ar源项产生及输运模型示意图
Figure 1. Schematic Diagram of 41Ar Source Term Generation in PWR Coolantand Its Transport Model
图 2 A机组某循环41Ar比活度变化趋势图
Figure 2. Variation Trend of 41Ar Specific Activity in a Cycle of Unit A
图 3 B机组某循环41Ar比活度变化趋势图
Figure 3. Variation Trend of 41Ar Specific Activity in a Cycle of Unit B
图 4 41Ar辐射影响验证分析点示意图
RCP—反应堆冷却剂系统
Figure 4. Schematic Diagram of 41Ar Radiation Impact Verification Analysis Points
图 6 B机组新循环41Ar比活度变化趋势图
Figure 6. Variation Trend of 41Ar Specific Activity in New Cycle of Unit B
表 1 某电厂A和B机组41Ar源项对比分析表
Table 1. Comparative Analysis of 41Ar Source Item for Units A and B
维度 41Ar 源项特点 A机组 B机组 初期阶段 上升期持续约3个月 上升期持续约4个月 中后期阶段 下降至稳定水平，末期比活度约1000 MBq/t 维持高位，缓慢上升，末期比活度约10000 MBq/t 比活度峰值 3701 MBq/t 10685 MBq/t 比活度峰值节点 循环初期 循环后期 40Ar 浓度
（平均）6.04 mg/L 17.4 mg/L 
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表 2 A和B机组41Ar管道辐射场贡献对比分析表
Table 2. Comparative Analysis of Pipeline Radiation Field Contribution by 41Ar for Units A and B
机组 取样比
活度/
(MBq·t−1)补偿比
活度①/
(MBq·t−1)接触剂量
率贡献/
(mSv·h−1)环境剂量
率贡献/
(mSv·h−1)实测接触
剂量率/
(mSv·h−1)A 1000 1429 0.064 0.006 0.8 B 7000 10000 0.450 0.039 1.2 注：①考虑到41Ar的半衰期较短，对取样后测量期间的衰减进行了补偿
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表 3 A和B机组41Ar加氢站热点对比分析表
Table 3. Comparative Analysis of 41Ar Hot Spot of Hydroge Refueling Station for Units A and B
机组 41Ar 气相
比活度/
(Bq·m−3)空间
体积/m341Ar 接触剂量率/
(mSv·h−1)环境
剂量率/
(mSv·h−1)实测接触
剂量率/
(mSv·h−1)A 8.97×1010 0.0224 4.29 0.43 7 B 6.28×1011 0.0224 30 3 33
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