Reactivity Effects of Steam Bubbles Injected into the BREST-OD-300 Reactor Core

• Published in: Atomic energy (New York, N.Y.) Vol. 130; no. 3; pp. 136 - 142
• Main Authors: Davydov, V. K., Zhirnov, A. P., Kalugina, K. M., Lemekhov, V. V., Moiseev, A. V., Smirnov, V. S., Umanskii, A. A.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-07-2021; Springer; Springer Nature B.V
• Subjects: Analysis; Boilers; Bubbles; Compression; Coolants; Density; Energy industry; Hadrons; Heavy Ions; Injection; Localization; Nuclear Chemistry; Nuclear Energy; Nuclear Physics; Nuclear power plants; Nuclear reactors; Physics; Physics and Astronomy; Pressure reduction; Reactivity; Reactor cores; Reactors; Separation; Steam
• ISSN: 1063-4258; 1573-8205
• DOI: 10.1007/s10512-021-00784-x

Possible scenarios for steam bubbles to be injected into the core in the event of depressurization of the pipes of the loop built into the steam generator are examined in the BREST-OD-300 pilot demonstration fast reactor with an integral construction of the lead coolant loop. The injection of steam bubbles into steam bubbles into the core bring about the steam void reactivity effect, which, depending on their volumetric content in the coolant, parameters, and localization on passage through the core, can change right up to a change in the sign of the effect. Calculations show that under the most conservative assumptions regarding the formation of steam bubbles and their movement through the loop the large difference between the density of lead and steam, the loop design, and the circulation pattern of the coolant that promote separation and compression of bubbles exclude the materialization of a large positive reactivity effect (Δϱ ≥ β) on injection of steam bubbles into the core. Under the hypothetical assumption that only small bubbles, avoiding separation and compression, appear and enter the core in an accident with depressurization of the steam generator, the materialization of a large reactivity effect is also excluded. The negative component of the steam with the high density inherent in small bubbles compensates the positive void component of the bubbles.