The SG secondary pH under SGTR condition is a key factor that affects the iodine partition coefficient and thus affects the SGTR radiological consequence. Higher pH favors a higher iodine partition coefficient and thus a lower radiological consequence. In this paper, the SG secondary pH under SGTR condition of HPR1000 is studied combine with the thermal-hydraulic analysis. A pH evaluation model using chemical equilibrium method is developed, and is validated by comparison with the measured pH. The transient thermal-hydraulic characteristics of SGTR event have been analyzed to determine the time variant chemical concentrations in the SG secondary side. Then, the SG secondary pH as a function of time is calculated by the pH evaluation model. The calculation results indicate that the SG secondary pH decreases from the initial value of 9.1 to approximately 6.5 by the end of the transient. An iodine partition coefficient of 197 is derived with the minimum SG secondary pH value of 6.5, which envelopes the suggested value of 100 in the regulations.

SGTR条件下的SG二次pH是影响碘分配系数并因此影响SGTR放射学结果的关键因素。pH值越高，碘分配系数越高，因此放射学结果越低。结合热工水力分析，研究了HPR1000在SGTR条件下的SG二级pH。建立了使用化学平衡法的pH评估模型，并通过与测得的pH值进行比较进行了验证。分析了SGTR事件的瞬态热工水力特性，以确定了SG二次侧中随时间变化的化学浓度。然后，通过pH评估模型计算SG二次pH作为时间的函数。计算结果表明，SG二级pH从初始值9降低。瞬变结束时从1到大约6.5。碘的分配系数为197，最小SG次级pH值为6.5，该值涵盖法规中的建议值100。