Study on Thermal Stratification of Marine Reactor Surge Line Based on Operating Data

The thermal stratification of marine reactor surge line is divided into four types of typical transient based on the operating data: power increase, power decrease, off-design conditions, and small spray flow. The dimensionless Richardson number (Ri) analysis and the numerical simulation calculation of transient conditions are performed separately for these typical transients, generating the thermal stratification section length, duration and maximum temperature difference along the horizontal line section of the surge line under these typical transients. As indicated by the results, the thermal stratification under power increase and decrease transient conditions extends through the surge line just once, and the surge line safety may be affected by the circulating thermal fluctuation at the joint under the power increase transient condition, the thermal stratification of long section, long time and large temperature difference in the horizontal section under the small spray flow transient condition, and the thermal stress fluctuation caused by the off-design conditions. The method of study on thermal stratification of surge line based on operating data, proposed in this paper, lays a foundation for the subsequent thermal stress and thermal fatigue analyses, and also provides reference for the thermal stratification studies of other volumetric equipment.