A separate paper is given in this meeting to describe the passive safety experiments in more detail. Here is only a short overview of the experiments.

1.1. Experiments with CMT and two PBL’s

The main objective of the tests was the overall simulation of the PSIS behaviour. The experiments demonstrated the capability of PACTEL for the simulation of PSIS’s [2, 3, 4, 5]. The data did not provide very detailed information about phenomena in the CMT. The instrumentation of the CMT in the first test series was limited. The tests were partially aimed for investigation of possibilities to run passive safety injection tests on PACTEL. The experience gathered during this first series was then used in the specification of the test parameters and instrumentation of the second series.

1.1.1. The first series ofpassive safety injection experiments (GDE-01 through GDE-05)

The first experiment series included five SBLOCA tests with break in one hot leg of PACTEL. Three break sizes were used. Three tests included secondary system depressurization as an accident management measure. In all tests, only PSIS provided ECC water to the core. The primary pressure used in the tests was lower than the nominal operation pressure of PACTEL. Maximum operation pressure of the passive accumulators determined the upper limit of the experiment pressure (3.8 MPa).

Although some problems with condensation in the CMT occurred no core heat-up was detected. It should be mentioned here that the CMT used in the test was very large, about twice as large as the scaled volume of four accumulators of the reference plant. On the other hand, the volume of the CMT is about the same as the volume of the rest of the loop. All the tests in this first series were terminated before the CMT was totally empty.

The second experiment series included four SBLOCA tests with break in one cold leg of PACTEL. Two break sizes were used. The tests also included studies of primary system depressurization and reproducibility of the phenomena. In all tests, only the CMT provided ECC water to the primary loop.

The primary pressure used in the tests was again lower than the nominal operation pressure of PACTEL. The maximum operation pressure of the passive accumulator limited the maximum experiment pressure to 3.8 MPa. Since one loop of PACTEL was equipped with a different steam generator model the tests run with only two loops in operation. There was still water in the CMT when the tests were terminated. During the rapid condensation period, water level in the core simulator dropped close to the top of the core. However, also in these test no core heat-up occurred.