Shutdown standards establishment

On the basis of the above, utilities have established concrete safety standards for shutdown and observe them to secure shutdown safety. They are paying attention to the cases of abnormal events experienced in other countries. 

The field connections to the safety sensors and outputs are established through dedicated safety certified input/output sub systems that carry the essential diagnostics and an independent means of shutdown in aecordance with the principles we have seen. Profisafe is a certified protocol with diagnostics and fail-safe responses. The system is designed to maintain functional independence for all safety functions in hardware and software. The standard Profisafe DP protocol can then share the same network to communicate with standard controllers and standard peripheral devices such as I/O sub systems or variable speed drives. 

In establishing the residual heat loads of the reactor (including decay heat, heat due to shutdown fission and stored energy), it should be assumed that the fuel has been exposed to operation at power for a period of time that would produce the maximum decay heat load and the decay heat should be evaluated consistently with applicable standards. 

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