What conditions constitute the reactor secured state?

What conditions constitute the reactor secured state?

• A. 1) the console key switch is off and the key is removed; 2) no work is in progress involving fuel, core structure, installed control blades, or control blade drives unless they are physically decoupled from the control blades; 3) no experiments being moved or serviced that have a reactivity worth exceeding 720 pcm.
• B. Only the first criterion is required.
• C. Only the second criterion is required.
• D. Only the third criterion is required.

Answer: (A)

Secured state means placing the reactor in a deliberately safe, lockout condition so that accidental or uncontrolled reactivity changes cannot occur. The three conditions together cover different risk areas: first, turning the console key switch off and removing the key stops any operator-driven restart and prevents inadvertent re-energizing of control systems; second, ensuring no work is in progress on fuel, core structure, installed control blades, or control blade drives unless they are physically decoupled from the blades removes the possibility that core configuration or control actions could change while secured; third, preventing movement or servicing of experiments with a reactivity worth exceeding 720 pcm avoids large, unanticipated reactivity insertions or withdrawals during the secured state. Taken together, all three must be satisfied to truly declare the reactor secured, because each addresses a different pathway to unsafe conditions. If any one condition isn’t met, there remains a potential for unintended reactivity changes or unsafe scenarios.

Secured state means placing the reactor in a deliberately safe, lockout condition so that accidental or uncontrolled reactivity changes cannot occur. The three conditions together cover different risk areas: first, turning the console key switch off and removing the key stops any operator-driven restart and prevents inadvertent re-energizing of control systems; second, ensuring no work is in progress on fuel, core structure, installed control blades, or control blade drives unless they are physically decoupled from the blades removes the possibility that core configuration or control actions could change while secured; third, preventing movement or servicing of experiments with a reactivity worth exceeding 720 pcm avoids large, unanticipated reactivity insertions or withdrawals during the secured state. Taken together, all three must be satisfied to truly declare the reactor secured, because each addresses a different pathway to unsafe conditions. If any one condition isn’t met, there remains a potential for unintended reactivity changes or unsafe scenarios.