The REWET-project was started with REWET-I single fuel rod simulator facility for generic studies of the basic phenomena of the reflood phase of a Loss-of-Coolant Accident (LOCA) of a nuclear power plant. It has continued with the REWET-II and REWET-III facilities.
The REWET-II facility was designed for the investigation of the reflooding phase of a LOCA. The main design principle was the accurate simulation of the rod bundle geometry and the primary system elevations. This was necessary in order to have the correct hydrostatic pressures for the reflooding process. The scale of the volumes was 1:2333. The reactor vessel was simulated by a stainless steel U-tube construction consisting of downcomer, lower plenum, core and upper plenum. The primary loops contained a pipe simulating the broken loop and a connection line between the upper plenum and downcomer simulating five intact loops. The containment was simulated by a preesure vessel. Steam generators and primary pumps were simulated with flow resistances. The ECC-water could be injected to the downcomer and/or to the upper plenum by a pump or from an accumulator.
The simulation of the fuel-rod bundle consisted of 19 indirectly electrically heated simulator rods. The heating coils were inside stainless steel cladding in magnesium oxide insulation. The heated length (2.4 m), the outer diameter (9.1 mm) and the lattice pitch (12.2 mm) of the fuel-rod simulators as well as the number and the construction of the rod bundle spacers were the same as in the reference reactor. Three different fuel rod simulator bundles had been used in experiments, two bundles with nine-step chopped cosine power distribution and one with uniform linear power.
REWET-II facility was constructed in 1981 and modified in 1985 by adding a steam generator and a pressurizer. Totally 76 experiments were carried out. The updated version of the facility was called REWET-III.
IMAGES: (from the year 1983)
REWET-II (two floors)
REWET-II (larger image)
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