二次中子源破损诊断方法研究与验证

Study and Verification of Diagnosis Method for Secondary Neutron Source Breakage

压水堆核电机组使用的二次中子源存在破损风险,反应堆功率运行工况下无法对二次中子源的状态进行物理检查。根据二次中子源的活化特性将^(122)Sb和^(124)Sb作为诊断二次中子源破损的特征核素,对使用一回路冷却剂的γ放射性在线监测数据、一回路冷却剂中^(122)Sb和^(124)Sb的比活度诊断二次中子源破损的方法可行性进行了分析,设计了二次中子源破损诊断流程,并使用上述诊断方法对二代改进型1000 MW级压水堆核电机组二次中子源破损问题进行了诊断。验证结果表明,二次中子源破损后一回路冷却剂取样分析得出的^(122)Sb和^(124)Sb比活度变化趋势与核辐射监测设备监测到的一回路冷却剂γ放射性变化趋势在总体上吻合。因此,本研究提出的二次中子源破损诊断方法是有效的。

The secondary neutron source used in the PWR nuclear power unit has a risk of breakage.Physical inspection of the status of the secondary neutron source is not possible at reactor power operation condition.According to the activation characteristics of the secondary neutron source,^(122)Sb and^(124)Sb are used as the characteristic nuclides to diagnose the damage of the secondary neutron source.The feasibility of the method for diagnosing the damage of secondary neutron source by using the on-line monitoring data ofγradioactivity of primary coolant and the specific activity of^(122)Sb and^(124)Sb in primary coolant is analyzed,the secondary neutron source damage diagnosis process is designed,and the secondary neutron source damage problem of the second generation improved 1000 MW PWR nuclear power unit is diagnosed using the above diagnosis methods.The verification results show that the specific activity change trend of^(122)Sb and^(124)Sb obtained by the primary coolant sampling analysis after the damage of the secondary neutron source should be consistent with theγradioactivity change trend of the primary coolant monitored by the nuclear radiation monitoring equipment.Therefore,the secondary neutron source damage diagnosis method proposed in this study is effective.