CSNI1004: UPTF/TEST5A/RUN063, Steam/Water Flow Phenom.Blowdown PWR Cold Leg Break LOCA

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CSNI1004 UPTF/TEST5A-RUN063. (Abstract last modified 05-NOV-1998)

UPTF/TEST5A/RUN063, Steam/Water Flow Phenom.Blowdown PWR Cold Leg Break LOCA

Abstract Table of Contents:

1. NAME OR DESIGNATION - UPTF/TEST5A-RUN063.

2. COMPUTER FOR WHICH PROGRAM IS DESIGNED AND OTHER MACHINE VERSION PACKAGES AVAILABLE -

To request or retrieve programs click on the one of the active versions below. A password and special authorization is required.

Explanation of the status codes.

Program-name Package-ID Status UPTF/TEST5A-RUN063 CSNI1004/01 Arrived

Machines used: Package-ID Orig.Computer Test Computer CSNI1004/01 Many Computers

3. DESCRIPTION OF TEST FACILITY - The Upper Plenum Test Facility (UPTF) is a geometrical full-scale simulation of the primary system of the four-loop 1300 MWe Siemens/KWU pressurized water reactor (PWR) at Grafenrheinfeld. The test vessel, upper plenum and its internals, downcomer, primary loops, pressurizer and surge line are replicas of the reference plant. The core, coolant pumps, steam generators and containment of a PWR are replaced by simulators which simulate the boundary and initial conditions during end-of-blowdown, refill and reflood phase following a loss-of-coolant accident (LOCA) with a hot or cold leg break. The break size and location can be simulated in the broken loop. The emergency core coolant (ECC) injection systems at the UPTF are configurated to simulate the various ECC injection modes, such as hot leg, upper plenum, cold leg, downcomer or combined hot and cold leg injection of different ECC systems of German and US/Japan PWRs. Moreover, eight vent valves are mounted in the core barrel above the hot leg nozzle elevation for simulation of ABB and B&W PWRs.
The UPTF primary system is divided into the investigation and simulation areas. The investigation areas, which are the exact replicas of a GPWR, consist of the upper plenum with internals, hot legs, cold legs and downcomer. The realistic thermal-hydraulic behavior in the investigation areas is assured by appropriate initial and boundary conditions of the area interface. The boundary conditions are realized by above mentioned simulators, the setup and the operation of which are based on small-scale data and mathematical models. The simulation areas include core simulator, steam generator simulators, pump simulators and containment simulator. The steam production and entrainment in a real core during a LOCA are simulated by steam and water injection through the core simulator.

4. DESCRIPTION OF TEST - This separate effects test was performed to investigate the steam/water flow phenomena in the intact cold legs, downcomer and lower plenum of a PWR during end-of-blowdown of a large cold leg break LOCA with cold leg ECC injection.
Boundary Conditions:
In this test the pump simulators of the three intact loops were closed. The hot leg of broken loop was closed. Initially, the lower plenum was filled with saturated water (13200 kg) at a system pressure of 18 bar to simulate the flashing and entrainment in the lower plenum during depressurization. The test was initiated by opening the cold leg break valve followed by subcooled ECC injection into the cold legs of the three intact loops.
Significant Findings:
The results showed that immediately after the start of ECC injection, water plugs were formed in the cold legs. After a short delay, the water plugs reached the downcomer causing intermittent ECC delivery to it. Initially, the ECC injected into cold leg 1 adjacent to the
break was completely bypassed while some of the ECC injected into cold legs 2 and 3 far away from the break penetrated to the lower plenum. Subcooled water was first detected in the lower plenum immediately after the plug entered the downcomer. ECC delivery from cold legs 2 and 3 to the lower plenum increased with decreasing upflow in the downcomer, and finally, all the ECC injected into these loops was delivered to the lower plenum. However, the ECC injected into cold leg 1 was mostly bypassed throughout the transient.

5. EXPERIMENTAL LIMITATIONS OR SHORTCOMINGS - The system operating pressure was limited to 20 bar. So for some experiments pressure scaling was necessary.

6. PHENOMENA TESTED - The test focuses on plug formation in the injecting cold legs, countercurrent flow or countercurrent flow limitation in the downcomer and ECC bypass.

7. SPECIAL FEATURES OF EXPERIMENT - Investigation of multi-dimensional flow behavior in a full-scale primary system of a 1300 MWe PWR.

8. COUNTERPART EXPERIMENTS - CREARE

9. STATUS
CSNI1004/01: 05-NOV-1998 Arrived at NEADB

10. REFERENCES  -
CSNI1004/01:
- UPPER PLENUM TEST FACILITY (UPTF)
  Test No. 5: Downcomer Separate Effect Test R515/87/16
  Experimental Data Report (Kraftwerk Union AG, September 1987)
- R. Emmerling et al.:
  UPTF: Program and System Description (U9 414/88/023, November 1988)
- J. Sarkar, J. Liebert, R. Laufer:
  Work Report, UPTF Test Instrumentation, Engineering Units and Computed
Parameters (S554/92/013, November 26, 1992)
- 2D/3D Program Work Summary Report
NUREG/IA-0126 - GRS-100 - MPR-1345 (June 1993)
- Reactor Safety Issues Resolved by the 2D/3D Program
NUREG/IA-0127 - GRS-101 - MPR-1346 (July 1993)

11. TEST DESIGNATION - TEST5A/RUN063

12. PROGRAMMING LANGUAGE -CSNI1004/01:

15. ESTABLISHMENT -
    Siemens AG, KWU, Postfach 3220,
    91050 Erlangen, FRG
    Germany

16. MATERIAL AVAILABLE -CSNI1004/01:
CCVM Data

17. CATEGORIES -

- Y. Integral Experiments Data, Databases, Benchmarks

Keywords: BLOWDOWN, DATA, LOSS-OF-COOLANT ACCIDENT