Core flow distribution in a General Electric Boiling Water Reactor as measured in Quad Cities Unit 1

Flow distribution at the inlet to the core of a General Electric boiling water reactor driven by jet pumps was studied experimentally at the Quad Cities 1 plant. Emphasis for this test was given to one-recirculation-pump operation with the equilizer valve closed. The flow test was conducted at atmospheric pressure and ambient temperature with all the fuel bundles in place and with the steam separator-dryer and vessel head off. Individual fuel bundle flow was measured with a specially fabricated flow measuring device at the exit of selected fuel bundles located symmetrically in the core. Results of the test indicated that flow through the various fuel bundles of the core during the one-pump operation mode does not vary more than +-1.9 percent from the average bundle flow rate at 95 percent confidence level, and this measured variation is randomly distributed over the core. Also, the two-pump data obtained from this test show essentially uniform flow distribution. This confirms the design assumption of uniform pressure distribution in the reactor lower plenum for both one- and two-pump operation. Since all jet-pump-driven boiling water reactors have similar hydraulic design bases with respect to the jet pump design and the lower plenum, this experimental program confirms that the pressure distribution for all of these BWRs is uniform