Auxiliary facilities instruments

So far as cooling air is concerned, the operator is warned by alarms on pressure and flow of air and also on radioactivity in the air stack. Air flow failure causes a. mild automatic safety action (slow setback see Table 5.5.A). 

In order that reactor operation may be as free as possible from the effects of transient disturbances or outages on the purchased-power lines, electrica1.power for the control system is obtained from a special supply, labeled Energy Conversion and Storage . in Fig. 5.1.A. This supply consists of two alternators operated from storage batteries. In normal operation one alternator would supply instrument bus voltage and the other alternator would supply relay bus voltage.  

The instrument bus furnishes power to those instruments most sensitive to disturbance while the relay bus (also called the control bus ) furnishes power to the less sensitive components, such as relays and motors, which not only are less sensitive to disturbance but are themselves actual sources of disturbance. If one of the alternator supplies breaks down or otherwise becomes unavailable, the relay bus would be switched to purchased power. To permit operation with the rougher purchased power, the relay circuits include a 2-sec timer and a number of time delay relays so that reactor shutdown does not ensue unless the r.elay bus voltage is off for 2 sec or longer. 

Reaction, of the operator to loss of control power is discussed briefly in Section 5.6.4. Annunciator signals from the control power center may be used to bring to the reactor control room information on such items as battery charger failure and frequency monitoring, but the main link between this center and the operator, both for conveying information to and action from the operator, will be by patrol operation on something like a once-per-hour basis. 

1 Safety Bod Clotctaes. Safety rod motion is obtained, in general, by the combined action of gravity and water flow. There is also the buoyant force, but it is expected that the downward acceleration will never be less than Ig. The safety action is therefore accomplished by releasing the shim  

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The heavy lines indicate the flow of energy from an external source to the control system to operate amplifiers, relays, etc., and to motors, magnets, and the auxiliary facilities to operate pumps, fans, etc. These are the principal power demands relevant to the control system. To.isolate the control system from fluctuations and interruptions of external power an energy conversion and storage unit is provided. The status of this unit is reported by certain instruments to the operator, who can exert a limited degree of... 

There are three groups of instruments, furnishing information to the operator and to the control system (1) the reactor instruments measuring neutron flux or power level, (2) the rod position and motion indicators, and-(3) the instruments for the auxiliary facilities and energy conversion and storage. These groups will be discussed in the order mentioned. The way in which the instrument signals are presented to the operator, recorded, or used in the control system will be discussed in later sections. 

The required operating capacity of a proposed facility is too small to permit continuous operation at a practical rate. Pumps, boilers, piping, instrumentation, and other auxiliary equipment generally have a minimum industrial operating capacity. 

All safety-grade systems in the PIUS plant are located within the reactor building which encloses the containment, the fuel handling equipment, the fresh fuel storage, the spent fuel storage pool and the emergency control room (the auxiliary shutdown facility) with associated instrumentation, control equipment and batteries for electric power supply. 

A. 1001. This chapter shall provide information concerning the auxiliary systems included in the facility. A description of each system, the design bases for the system and for critical components, a safety evaluation demonstrating how the system satisfies the requirements of the design basis, the testing and inspection to be performed to verily the system capability and reliability, and the required instrumentation and... 

A. 1005. All water systems of the facility that have not been described previously shall be discussed in this section. These may include the primary purification system, the service water system, the cooling system for reactor auxiliaries and the primary coolant make-up system. In each case, the information provided should include the design bases, a system description, flow and instrumentation diagrams, a safety evaluation, if required, testing and inspection requirements, and instrumentation requirements. 

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