CSNI0038 LOBI/A2-81.

1. NAME OR DESIGNATION:  LOBI/A2-81.

3. DESCRIPTION OF TEST FACILITY

The LOBI-MOD2 test facility is a high pressure integral system blowdown refill test facility designed, constructed and operated at the Joint Research Centre of the European Communities, Ispra Establishment, Italy. It represents and extensive modification of the original MOD1 configuration and was put into operation after shutdown of the MOD1 configuration in June 1982.
   The LOBI facility is a 1/700 scale model of a four loop PWR and has two primary loops, the intact loop representing three loops and the broken loop representing one loop of a four-loop PWR.  The reactor pressure vessel model contains an electrically heated rod-bundle with 64 rods and a heated length of 3.9 m. The nominal heating power is 5.3 MW.  The downcomer is of annular shape.  An upper head simulator is connected to the vessel. Each of the two primary loops contains a pump and a steam generator. The different mass flows in the loops are established by different pump speeds, since the two pumps are identical. ECC water can be supplied from two accumulators, one for each loop.  Cold or hot leg as well as combined injection can be simulated. Heat is removed from the steam  generators by a secondary system.
In the MOD2 configuration, emergency core cooling (ECC) water can be supplied by the high pressure injection system (HPIS) and by the accumulator injection system (AIS).
The LOBI test facility is the only high pressure integral test facility within the European Communities (1982), built and operated in the Joint Research Centre, Ispra, ITALY. In the LOBI experiments  the thermal-hydraulic behavior of the facility during a transient, caused by a simulated loss of coolant accident (LOCA), is investigated to provide an experimental basis for analytical model development and code verification.

4. DESCRIPTION OF TEST

Test A2-81 simulates a 1% cold leg break in the main coolant pipe of a pressurized water reactor. Cooldown is effected via the secondary loop at a rate of 100 K/h. Emergency cooling water is injected into the primary loop by cold leg high pressure injection (HPIS) representative of two injection pumps; of the remaining two pumps in the reference plant, one is assumed to be in maintenance and the other connected to the broken loop.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM: EXPERIMENTAL LIMITATIONS OR SHORTCOMINGS

6. PHENOMENA TESTED

Natural circulation in 1- and 2-phase flow; asymmetric loop behaviour; phase separation; ECC mixing and condensation; heat transfer; 1- and 2-phase pump behaviour.

7. SPECIAL FEATURES OF EXPERIMENT

LOBI's large size and full height components are considered an advantage. Test A2-81 has been made available for the International Standard Problem No. 18 exercise to perform LWR safety system computer code comparison calculations for the "double-blind" post-test prediction of the experimental results.

8. COUNTERPART EXPERIMENTS

Semiscale. A direct counterpart experiment is LOBI Test A1-82, which is performed identically but with high pressure injection into the hot leg of the intact loop.

- L. Piplies and G. Leva:
Quick Look Report on LOBI Test A2-81
ISPRA LQC 85-28 Communication No. 4022, April 1985
- E. Ohlmer and J. Sanders:
Experimental Data Report on LOBI Test A2-81
ISPRA LEC 84-30, Communication No. 4019, November 1984
- B. Worth and H. Staedtke:
Post-Test Calculation Report LOBI-MOD2 Test A2-81 (ISP-18)
ISPRA LPC 85-19 Communication No. 4033 October 1985
- H. Staedtke:
LOBI-MOD2 Small Break Loca Experiment Final Comparison Report
ISP-18 (CSNI Report 133) April 1987
- International Standard Problem No.18
LOBI-MOD2, 1% Cold Leg Break Experiment
- W. Kolar and W. Brewka:
LOBI Experimental Data Tape - Format Description
Technical Note No.I.06.C1.85.49 (May 1985)
- LOBI Project - RELAP5 Base Input Data for LOBI-MOD2
LPC 85-18 (February 1985)

11. TEST DESIGNATION:  A2-81

15. ESTABLISHMENT

        Commission of the European Communities
        Joint Research Centre
        Ispra Establishment
        I-21020 Ispra
        ITALY

CCVM data        mag tapeISP 18, 1% COLD LEG BREAK                  CVMTP