User's manual of safety map code SWAC-10-MJ/2; Evaluate detector capability against small leak sodium-water reaction

Watanabe, Osamu*; Kishida, Masako*; Shirataki, Koji*; Hirazawa, Yoshiya*

PNC TJ906 79-02, 109 Pages, 1979/12

PNC-TJ906-79-02.pdf:2.29MB

Water leak detectors-hydrogen concentration meters are equipped with secondary cooling system of LMFBR to detect small leak of water from heat transfer tube in steam generator. Leak rate region to be able to detect the water leaks before secondary tube failure is decided by using the concept of so-called "safety map". Computer code "SWAC-10-MJ/2" provides the safety map for secondary cooling system of proto-type reactor. This paper is written for user's manual of the code. Performance of "SWAC-10-MJ/2" code is as follows; (1)Secondary cooling system of proto-type LMFBR is selected for calculation object. (2)Wastage rate equations proposed by PNC are accepted. (3)The relation between the initial leak rate and the enlargement of the leak hole is enabled to be feeded as an input. (4)The enlargement by self wastage is taken into account in calculating the change of hydrogen concentration. (5)Effect of mixing of hydrogen in sodium is introduced for plenum regions. (6)Detectability of water leak in stagnant sodium (in the down-commer region) by means of hydrogen detectors is enabled to be evaluated. (7)Movement of hydrogen between sodium and cover gas is enabled to be evaluated. (8)Hydrogen diffusion process in Ni membrance of hydrogen detector is introduced. (9)The number of calculating points of leak rate is 50 points, and the range of calculation time is about 20,000 seconds. (Time mesh size; 4 seconds and Calculating step; 5,000 steps) By the way, the region size needed is about 470KB and the computing time for IBM 370/168 is about 0.83 msec/point of leak rate/step.