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The test facility was originally designed to model the Finnish Loviisa plant but it was redesigned and modified for this test programme. The facility can be operated at atmospheric pressure with loop and high pressure injection flows from different cold legs in the area of interest to the pressurized thermal shock.
The test facility was initially constructed as a 1 to 2.56 scale model of the Loviisa VVER-440 reactor. The facility contains a half of the circumference of the reactor downcomer made of acrylic plastic. The downcomer is semiannular in shape.
In 1985 model tests were performed at the Hydraulic Laboratory of Imatran Voima Oy in Finland to study mixing of emergency cooling water with primary water in the USNRC-IVO downcomer during a postulated loss-of-coolant accident. The test matrix consists of 20 tests. The varied parameters were flow rates and the number and configuration of cold legs with high-pressure injection and loop flows. Four tests were done with decreasing loop flow temperature to simulate primary flows during steam line breaks.
Transparent materials were used to allow flow visualization during the tests. The choice of transparent materials limits the upper temperature to 75 deg.C. The fuel buoyancy effect was induced by salt addition and the high-pressure injection temperature was used as a tracer.
Study mixing of emergency cooling water with primary water in a semiannular downcomer during a postulated loss-of-coolant accident, with interacting flows from cold legs.
- Harri Tuomisto and Pertti Mustonen:
Thermal mixing tests in a semiannular downcomer with interacting flows from
cold legs, IVO Report RLB 340
- Additional fluid and thermal mixing tests in the USNRC-IVO downcomer
IVO Report RLB 341