Plant Operating Standard

PR-18 Relief System

Normal Operation

• 1. Pressurizer is protected by the diaphragm-operated relief valve (PR-3V), set to begin opening at 1930 psig, and to be fully open by 2000 psig, and also by one of the two spring-operated valves (PR-1V or PR-24V), set to open at 2000 psig. The other spring-operated valve is operable and the transfer valve (PR-25V) is operable.

  NOTE: Transfer valve PR-25V should not be actuated while plant is hot, unless through necessity. This is to prevent thermal shock to the idle spring-operated valve.

• 2. The ECT is full to a level of 30 1/2 in., at atmospheric pressure and ambient temperature. The vent valve (PR-9V) and overflow valve (PD-39V) are closed and operable. Relief valve (PR-7V) is operable and set for 50 psig.

  [ECT is Effluent Condensing Tank, PR-T1. It must contain enough water for thermal mass to condense relief effluent.]

• 3. Primary relief valve leakage coolers PR-C1 and PR-C2 are in operation.
• 4. The primary gate valve stop-check bypass valves (PR-10V and PR-11V are open.
• 5. The four boiler relief valves are seated properly and set to operate at 800 psig.
• 6. The purification system relief valve (PR-4V) is seated properly and set to operate at 150 psig.

Minimum Conditions for Reactor Operation

• 1. One spring-loaded valve protecting the pressurizer.
• 2. Both relief valves on one steam generator are seated and operating properly.
• 3. The purification system relief valve is seated an operating properly.