CSNI0074 LOBI/BT-00.

1. NAME OR DESIGNATION:  LOBI/BT-00.

3. DESCRIPTION OF TEST FACILITY

LOBI-MOD2 is a non-nuclear two loop, high pressure integral system test facility for PWR safety research. It simulates the cooling system of a four-loop 1300 MWe PWR. It is especially designed for large and small break loss-of-coolant experiments and for special transient accident investigations. Emphasis is placed on the influence of loop components and of emergency cooling systems on the course of a reactor accident transient.

4. DESCRIPTION OF TEST

LOBI tests provide experimental data for checking and improving computer codes. In addition, they demonstrate the performance of reactor safety systems and procedures.
  
MOD2 is an extension of MOD1 25 large break loss-of-coolant experiments by the addition of components as needed for small break tests, e.g. scaled steam generators, a high pressure injection system (HPIS), secondary auxiliary feedwater injection (AFW), additional instrumentation and complete thermal insulation.
  
Test BT-00 belongs to the LOBI special transient test program and is part of the B-test series. Within the LOBI special transient test matrix this test is also called "ST-2" (scoping test no.2). Test BT-00 simulates a loss of main feedwater (LOFW) followed by a steam generator dryout and a subsequent cooldown via primary bleed and feed.
  
Scaling: The power input, the primary circuit coolant mass flow and volume are scaled down from the reactor values by a factor of 712. All the other most relevant quantities such as operating temperature, pressure, lengths and pressure drops along heat transfer surfaces have been scaled 1:1. Also the absolute heights and relative elevations of the individual system components have been kept at reactor values thus preserving the gravitational heads.

6. PHENOMENA TESTED

Test BT-00 consists of three consecutive phases:
- Phase 1 simulates a loss of main feedwater transient (LOFW) causing a boildown of the secondary water inventory in the steam generators followed by power scram.
- In phase 2 also auxiliary feedwater supply is interrupted to cause dryout on the secondary side and thus a primary side heat-up.
- In the final phase 3 the system is cooled down by primary side bleed and feed.
The test investigates the possibility of reproducing LOFW transients with the LOBI facility in a similar way as they would be expected for the reference plant.
  
Particular phenomena of main interest from this test are the heat-up after loss of main feed, cooldown after scram, heat-up after loss of secondary inventory and the final cooldown. During both heat-ups, pressurizer relief valve (PORV) opening is observed. The final cooldown by primary bleed and feed is performed with an open pressurizer relief valve and cold leg high pressure injection (HPIS) at an injection rate representative of two injection pumps. The behavior of the LOBI steam generators at low secondary inventories was also studied at the previous tests A1-76 and A2-90.

- 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)
- J. Sanders and E. Ohlmer:
Experimental Data Report on LOBI-MOD2 Test BT-00 (LOFW)
(ISPRA LEC 86-38, Communication No. 4038)  April 1986

11. TEST DESIGNATION:  BT-00.

15. ESTABLISHMENT

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