The rupture that is being considered here is a large leak in one of the main cooling water lines of the intermediate cooling system. If a small leak occurred in one of the smaller lines, the condition would probably be annunciated, and the operation of the system would not be affected greatly after the leak was isolated. The rupture that is being considered here will prevent further normal operation until the leak is repaired and system operation resumed. All of the other systems which are normally cooled by this system will be affected by this failure. Some will be affected to a lesser degree than some of the others. Normally cooling water is supplied to the following components:
Once buffer seal water flow to the buffer seals has been stopped, no control rods should be moved out of the reactor. The shaft in the reactor will heat to reactor temperature and upon withdrawal may bind to the extent that it would not scram.
Since cooling water flow is not available, the emergency cooling system will have to be brought into service.
The flow through the primary loop purification and buffer seal systems is closed off as soon as possible. In the purification system this action protects the ion exchanger resin from hot primary water. The buffer seal system is secured to keep the pressurizer level nearly constant with no letdown flow, and to prevent raising the temperature of SL-T1.
Tripping the T.G.'s as soon as possible prevents extracting large quantities of heat from the primary system, and thereby causing contraction and requiring a makeup rate beyond the capability of Emergency Makeup Pump. Conservation of the primary system temperature will facilitate startup.
With no buffer seal water being delivered to the buffer seals during this period of time, the buffer seal temperature will increase. The only part in the seals which will be affected by this condition is the lower O-ring which seals off the inlet flow between the capsule and the housing at the reactor end of the seals. Because of their proximity to the reactor nozzle flange, they can consequently see a temperature in excess of 350F only if the seal water flow is not re-established after two hours time. If these O-rings remain at a temperature of 350F or greater, the Buna-N material of which they are made begins to harden and consequently reduces their effectiveness as a seal ring. However, it would take six to eight hours before they harden to the point where leakage will occur past these rings. After the intermediate cooling system is restored to service and the buffer seal system put into service again, the inward leakage through the seals should be observed. IF this leakage did not exceed one gpm through each seal, the normal operation of the buffer seal and primary loop purification systems would not be affected.
The ship's service air system should be connected up down-stream of the instrument air compressor to keep the pneumatic instrumentation operating. The instrument air compressors must be turned off because of possible damage due to overheating. When the compressor comes off the line, all the pneumatic instrumentation will be lost in 3 to 4 minutes if the ship's service air system were not connected up.
In an emergency, any primary system pump may be operated without CW flow for the following time periods:
The loss of cooling water for approximately 30 minutes to the reactor shield tank cooling coils, containment cooling coils, Quantichem and Larson-Lane Coolers, and the hydraulic power supply coolers will not adversely affect the operation of the plant.
In placing the buffer seal system back in operation, the water to the seals should be put on slowly by either of the following methods in order to prevent thermal shock to the seals and shafts:
Before any rods are moved, seal flow should be established for the following period of time prior to moving rods: Fifteen (15) minutes plus the amount of time seal flow was "OFF", up to a maximum of four (4) hours.