A Natural circulation rate computer code for a single channel; Users' manual of computer code "NASCH"

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The removal of decay heat from a pressure tube type reactor at a loss of power accident (LOPA) or a total black out (TBO) depends on natural circulation with low water level. In this case, the information on the natural circulation rate is one of the important items to estimate the ability of core cooling. This report is a users' manual of a computer code "NASCH" which calculates the steady natural circulation rate for a single channel loop. This code can deal with the natural circulation in not only the HTL loop but also HWR. The validity of this code is confirmed by comparison between the calculated results and the HTL data. The program is written in Fortran and its size is 160 Kbyte.