CSNI1027 IVO/LOOP-SEAL.

IVO/LOOP-SEAL, IVO-Loop Seal Facility (Air/Water), Two-phase behaviour of a PWR cold leg loop seal during LOCA accidents

NAME OF EXPERIMENT, COMPUTER, DESCRIPTION OF TEST FACILITY, DESCRIPTION OF TEST, PHENOMENA TESTED, STATUS, REFERENCES, TEST DESIGNATION, LANGUAGE, ESTABLISHMENT, MATERIAL, CATEGORIES

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1. NAME OF EXPERIMENT: IVO/LOOP-SEAL AIR/WATER.

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2. COMPUTERS

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Program name	Package id	Status	Status date
IVO/LOOP-SEAL	CSNI1027/01	Report	01-JAN-1988

Machines used:

Package ID	Orig. computer	Test computer
CSNI1027/01	Many Computers

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3. DESCRIPTION OF TEST FACILITY

The experimental facility is a full-scale model of one entire cold leg. The steam flow is modelled with atmospheric air flow delivered by the high-capacity fan (3 m3/s with a head of 30 kPa). The maximum available superficial air velocity is 9 m/s in the cold leg with a diameter of 850 mm. The opening simulates a break in the long horizontal section between the RCP and the reactor pressure vessel (RPV). The RCP mock-up has been designed to give a similar flow behaviour: the overflow edge and the single-phase pressure drop are equal to those of the real RCP. The break location can be varied to simulate a botton, side or top break. The speed-controlled air fan has a buffer tank (10 m3) and throttling for the control of oscillations. Make-up water can be injected into the loop seal section with a maximum flow rate of 30 kg/s.
The measuring system records the pressures p1 and p2, and the air and make-up water flow rates. The differential pressure measurements in the horizontal section of the loop seal give average void fractions (or level values of the stratified flow).

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4. DESCRIPTION OF TEST

Three separate air/water test series were performed to determine the onset of slugging in the horizontal pipe, the residual water mass and the total two-phase drop in the loop seal. The results of flow regime transition experiments have been compared with smaller-scale experiments and with theoretical predictions to evaluate scaling criteria. The strong hysteresis of transitions found between the stratified and slug flow regimes depends on the loope seal geometry and U-tube oscillations.

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6. PHENOMENA TESTED

Study two-phase of a PWR cold leg loop seal during loss-of-cooland accidents.

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9. STATUS