Wednesday, May 19, 1999

Test A—single inlet, single outlet, external tank injection

Please note the time shift in the inlet temperature history (the front enters the simulation boundary 3.6 seconds sooner) and the larger measured core pressure drop (from a steady state of 5 in H₂O to 6 in H₂O).

Initial investigations have shown that heat losses are below 10% over the duration of the transient (approximately 60 seconds).

Approximately 20 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 good repeatability.

The primary system is initially well mixed at 74°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

In addition, velocity measurements from the visualization facility show the expected velocity distribution as a function of time at the simulation boundary inlet.

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

Figure 2 shows the temperature measured by the central thermocouple as a function of time during the test. The other two functioning inlet thermocouples read within the instrument error of 1° C. Two other thermocouple (these are very fine instruments) have failed. NOTE THAT THE TEMPERATURE BEGINS TO DROP ABOUT 3.6 s EARLIER THAN GIVEN IN THE DECEMBER 1998 POSTING. The temperature history can be downloaded in text format through inletT.txt or from the master data rBCTestA.xls worksheet.

Figure 2. Inlet temperature history for test A

The slug injection flowrate was determined from the level drop of the injection tank. 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 rBCTestA.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. Note that the cells used in early tests were replaced when shifting of the zero was noticed from test to test. The newer probes showed that the initial calibration was off by approximately 20% at full flow. A backfit calibration was done on the data and the new core dp history was plotted along with the old history on figure 4. The core dp history can be downloaded in text format through coredp.txt or from the master data rBCTestA.xls worksheet.

Figure 4. Core pressure drop history for test A

Velocity Distribution at Inlet

Visualization facility measurements confirmed the expectation that the radial velocity profile is relatively flat after the flow straightener. Figure 5 shows the measurement configuration.

Figure 5. Inlet velocity measurement configuration—from visualization facility

Mean and rms velocities were measured in the flow direction and radially. Rms measurements demonstrated the absence of significant structures in the bulk of the flow. The radial measurements showed that any flow other than streamwise is negligible. Figure 5 shows the radial streamvise velocity from zero flow up to the full flowrate; the profile remains relatively flat throughout. The mean streamvise velocity profile can be downloaded can be downloaded in text format through Umean.txt or from the master data rBCTestA.xls worksheet. The rms streamwise velocity, and the mean and rms cross-stream velocities are also included in the master data rBCTestA.xls worksheet.

Figure 6. Mean streamwise velocity transient profiles after the flowstraightener

Required Code Predictions

As decided during the 1st workshop, code predictions will be compared with data collected by downcomer thermocouples--see ISP TC Locations.  For the full interpretation of essential code predictions full data dumps at 10 time points will be needed.  Based on experimental data, the relevant 10 time points are:

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