Wednesday, May 19, 1999

Test B—single inlet, single outlet, steam generator injection

The Loop is operated as a closed system throughout this test series.  The slug is placed at the bottom of SG A.  When pump A1 is started, the slug proceeds through CL A1 into the downcomer, up through the core and exits through HL A.  All other cold legs are isolated.

Heat Losses

Initial investigations have shown that heat losses are below 20% over the duration of the transient (approximately 200 seconds).

Four tests were run with the boundary conditions given to participants (93% pump speed and approximately 60°C temperature difference between the primary coolant and the front). The tests show great repeatability.

The primary system is initially well mixed at 69°C.

The simulation boundary conditions consist of:

-slug flow rate as a function of time,

-temperature as a function of time at the inlet of the simulation boundary, and

-pressure drops in the core region.

The locations at which the data was measured are indicated on Figure 1.

Figure 1. Recommended simulation boundary

All data is collated in the BCTestB.xls (Microsoft Excel 97) worksheet.

Figure 2 shows the average temperature measured by the three working inlet thermocouples as a function of time during the test. The three inlet thermocouples read within the instrument error of 1° C. Two other thermocouple (these are very fine instruments) have failed.  The temperature history can be downloaded in text format through inletT.txt or from the master data BCTestB.xls worksheet.

Figure 2. Inlet temperature history for test B

The flowrate was determined from the calibrated ultrasound flowmeter.  Figure 3 shows the injection flowrate time history. The slug injection flowrate history can be downloaded in text format through flow.txt or from the master data BCTestB.xls worksheet.

Figure 3. Slug injection flowrate history for test A

Two dp cells measure the static pressure drop from the lower plenum to the exit hot leg flange. The average (between the two cells) core dp history is plotted in figure 4. The core dp histories (of both cells and their average) can be downloaded in text format through coredp.txt or from the master data BCTestB.xls worksheet.

Figure 4. Core pressure drop history for test A

Required Code Predictions

As decided during the 1st workshop, code predictions will be compared with data collected by downcomer thermocouples--see ISP TC Locations.  Since this transient is a slug (as opposed to the test A transient, which was a front) a longer simulation period is relevant.  The minimum has to cover 60 seconds after the cold slug reaches the simulation boundary inlet.  At least twelve full data dumps (rather than 10--as was agreed during the workshop) are necessary to capture the significant aspects.

Please also make sure to keep track of and document the mass balance during the transient.