From the above experimental study the following conclusions can be made.

(1) The total drain water quantity during the safety valve discharge is no more than 20 % of the initial water inventory, no matter whether the safety valve is full open or not. ( this is confirmed by the heat balance) .

The drain velocity and flow rate can be calculated by the critical flow theory.

(2) For the discharge caused by breaking of a pipe from the steam plenum, the drain quantity depends on the position of the pipe in the steam volume. During the discharge process water may be drained discontinuously. The bigger the pipe diameter, the more the discharged quantity. The total drain water quantity is more than for the opening of the safety valve at the same discharge orifice diameter.

(з) For the discharge from the water volume, the drain quantity is more than that of a drain from the steam volume. All water above the pipe opening will be drained. When the level is lower than the opening of the pipe, the drain quantity depends on the height difference between the liquid level and the opening of the pipe. In a certain range the bigger the height difference, the smaller the drain quantity. Under the conditions of our tests, when the height difference is more than 5cm, its effect on the quantity can be negligible.

References

1. Ma Changwen, Bo Jinhai, Za Meisheng and Others:

“ Safety experimental study for the Nuclear Heating Reactor ” INET Report, 1991, 2.

2. Ja Haijun

Safety experimental study on the Boron injection system of the 5MW Heating Reactor, doctoral thesis. 1991, INET, Tsinghua Univ.