Start-upAvill be defined as the point of commencement of control rod withdrawal or at the commencement of withdrawal of a specific group of rods, Normally, a reactor is considered shut down when the core is 1000 milliNiles reactivity below critical condition. Therefore start-up will be deemed to have commenced at some convenient stage of control rod withdrawal. This will normally be chosen at worst reactor condi­tions to ensure that the reactor remains subcritical in any event.

Checks on the state of the plant’s readiness will be made just prior and after the start-up has com­menced. The majority will be before start-up has com­menced as defined in the operating documents. The operating documents must clearly define the sequence and checks to be carried out and take the operator through the correct route for a successful start-up. Acknowledgement at each stage must be made by a signature at each step and major stages acknowledged by a senior person, usually the shift manager, for further progression.