Emergency Operating Procedure

EOP 2 Loss of All AC Power to the Main Bus

Revision 1, 2/6/64

A. Symptoms

B. Immediate Actions

C. Follow-Up Action

D. Discussion

A loss of power from either turbine-generator will normally result in an immediate automatic startup of the two 750 KW auxiliary diesel generators and automatic tripping of the ship's non-vital loads. The casualty considered here is a loss of all power to Bus 1 and Bus 2 of the main switchboard which will occur only if both turbine-generators trip from the line and both diesel generators fail to start up and synchronize. Among the possible causes of such a failure are the following:

On loss of all power to the main busses, the 300 KW emergency diesel generator will start automatically, and the emergency cooling system will go into operation. Emergency sea water pump DK-P1 and emergency canned pump DP-P2 will start, and valves DK-4V, DK-19V, DK-20V, DK-21V, and DK-32V will be opened to the full open position by their motor operators. The ship's emergency lighting will operate from the 120V A-C/D-C temporary bus. All other equipment necessary for safe operation of the ship will operate from the 450 V A-C bus or the 120 V A-C bus of the emergency switchboard. Operation of the emergency diesel generator will be indicated by its WHITE light on the mimic panel. Closing of the emergency diesel generator circuit breaker will be indicated by its BLUE light. The 120V, single phase, A-C bus will be available for critical instrumentation provided the D-C/A-C MG sets are not lost as a result of the same accident which caused loss of power to the main buses. Operation of these motor generators will be indicated by their WHITE lights on the mimic board. Closed circuit breakers on the 120V bus will be indicated by the Blue circuit breaker closed lights.

The immediate results of loss of power on the main buses will be loss of power to all four primary pumps with primary flow decaying quickly to a very low value. The operator's first concern is to check that the measures necessary to protect the reactor from damage have proceeded automatically. He might ensure that all rods have scrammed and that the emergency cooling system has started along with the emergency diesel generator. Since the emergency cooling system is controlled from the emergency cooling panel on the navigation bridge deck, an operator must go to the emergency cooling system as soon as it starts, to isolate the emergency cooling system from the console if necessary and to control the rate of cooling.

Subsequent action, in general, should be that required to place the 750 KW auxiliary diesel generators in operation allowing a normal shutdown if one generate can be started or resumption of operation if both can be started. Action should then be initiated to restore the turbine-generators to operation leading up to restoration of normal plant operation.

My text copyright 2020 Tommy Johnson, all rights reserved. I believe the Savannah documentation is property of MARAD or the US government.