Natural circulation experiments with a VVER reactor geometry

Stephen Lomperski, Jyrki Kouhia

Research output: Contribution to journalArticleScientificpeer-review

9 Citations (Scopus)


Experiments were conducted to study natural circulation behaviour in the PACTEL facility, a medium-scale integral test loop patterned after Soviet-designed VVER pressurized water reactors. Using stepwise inventory reduction and small-break experiments, primary loop flow behaviour was studied over a range of coolant inventories. The tests revealed a trend toward decreasing primary side mass flow rate with inventory. In the small-break experiments, flow stagnation and system repressurization were observed when the water level in the upper plenum fell below the entrances to the hot legs and coolant flow into the hot legs changed from single to two-phase flow. The cause of this flow interruption was attributed to the hot leg loop seals, which are a unique feature of the VVER geometry. Finally, an experiment was conducted to demonstrate how loop seal refilling behaviour at low coolant inventories depends upon the steam flow rate through an individual hot leg. It was shown that loop seal refilling results when low steam velocities permit countercurrent flow in the upflow side of the loop seal.
Original languageEnglish
Pages (from-to)409-424
JournalNuclear Engineering and Design
Issue number3
Publication statusPublished - 1994
MoE publication typeA1 Journal article-refereed


Dive into the research topics of 'Natural circulation experiments with a VVER reactor geometry'. Together they form a unique fingerprint.

Cite this