Study of behavior of running parameters after scram on Nuclear Ship MUTSU

It is very important for an operator on Nuclear Ship to control the plant after scram properly, in order to prevent the nuclear plant condition from exceeding the permitted limits and to regain her propulsion rapidly. And the proper control needs an exact knowledge about the transient pattern of some principal parameters such as primary coolant temperature, steam flow, bus electric power and etc. Present paper describes characteristic behavior of these parameters every 0.1 second, 1 second and 1 minute after scram, in connection with the sequential workings of the equipment and the manual operation. And it includes a study about the effects of the reactor power before scram. As the results of the present investigation, for example concerning primary coolant temperature, some phenomena worthy of mention are here. (1) The instantaneous rate of temperature drop runs up to 1000 degC/h immediately after 100% scram. (2) Transient of the rate of temperature drop always calms down after two peaks. (3) The maximum value of temperature drop is mainly influenced by manual operation. It would be useful for an operator to know the cause-and-effect relationship between the behavior of principal parameters and the operation after scram. (author)