Supplementary control rooms

In addition to the main control room, various types of supplementary control rooms and control locations are used. Details of nomenclature and allocation of functions vary among Member States, but other control rooms and control locations include  

Further information can be found in Ref. [4]. Guidance on design is provided in the following. 

The Requirements for Design require (Ref. [1], para. 6.75) that sufficient l C equipment be available, preferably at a single location that is physically and electrically separate from the control room, so that the reactor can be placed and maintained in a shut down state, residual heat can be removed and the essential plant variables can be monitored in the event of a loss of ability to perform these essential safety functions in the control room. This instrumentation is typically situated in a supplementary control room. 

Suitable provision should be made for transferring priority control to a new location and isolating the equipment in the main control room whenever the main control room is abandoned. 

The design basis of a nuclear power plant is usually such that loss of availability of the control room due to a PIE is very infrequent. It is therefore not necessary to postulate that a second PIE will occur when the main control room is unavailable and the necessary safety functions are being performed from a supplementary control room. 

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Suitable alarm systems and means of communication shall be provided so that all persons present at the research reactor faciUty and on the site can be warned and instructed, even under accident conditions. The availabihty of the means of communication necessary for safety within the research reactor facility shall be ensured at all times. Means of communication shall be available in the control room and also in the supplementary control room if there is one This requirement shall be taken into account in the design and in the diversity of the means of communication selected for use. 

For further discussion of the supplementary control room, see para. 6.144. 

Where necessary, a supplementary control room, separated and functionally independent from the main control room, shall be provided where the staff could operate in the event of an emergency. Information on important parameters and the radiological conditions in the facility and its surroundings shall be made available in the supplementary control room. Systems designed for this purpose shall be considered safety related systems. 

This subsection should provide an appropriate description of the supplementary control room, including the layout, with an emphasis on the human-machine interface. The electrical design standards for equipment signals routed to the supplementary control room have already been described in previous sections and need not be repeated here. The means of physical and electrical isolation between the plant systems and communication signals routed to the main control room and the supplementary control room should be described in detail to demonstrate that the supplementary control room is redundant and independent of the main control room. The mechanisms for the transfer of control and communications from the main control room to the supplementary control room should be described in detail so as to demonstrate how this transfer would occur under accident conditions. 

The human-machine interface shall be designed to provide the operators with comprehensive but easily manageable information, compatible with the necessary decision and action times. Similar provisions shall be made for the supplementary control room. 

Criterion 66. Supplementary control room Requirements for the control room should also apply to the supplementary control room. 

Information about actions important to safety taken by operators outside the main control room should be available immediately in the control room, except in situations where the control room has been damaged or abandoned. In this case, the necessary information should be available in a supplementary control room. 

Operator interfaces to the plant are primarily located in the main control room, technical support centre, supplementary control rooms and emergency control centre. These facilities contain safety related displays, safety related controls, accident monitoring systems, alarm annunciators and historical data systems. Guidance on the design of these facilities and systems is provided in this section. 

The design of supplementary control rooms should include suitable provisions for preventing unauthorized access and use. 

Manual control from a supplementary control room should, in general, be accomplished by simple actions such as operating a switch or pressing a button. To the extent possible, displays and controls should be similar to those in the main control room. 

The design of the main control room and the supplementary control rooms should be such that no PIE can simultaneously affect both the main control room and the supplementary control rooms to the extent that required safety functions cannot be performed. 

It should also be ensured that either the main control room or a supplementary control room can be given the necessary priority for initiating a particular safety function. 

Applicable parts of other sections of this Safety Guide should be taken into account in the design of supplementary control rooms, and the differences in purpose and use between the supplementary control rooms and the main control room should be given due consideration. 

Due consideration should also be given to ensuring that an adequately qualified access path is provided in the design to permit operators abandoning the main control room to move safely and conveniently to the supplementary control rooms. 

An adequate indication of potential hazards (such as smoke) and countermeasures (such as breathing masks) should be provided along the quahfied access path from the main control room to the supplementary control rooms. 

The supplementary control rooms should be located and configured so that operators can commence their duties at the new location within an acceptable time limit. 

Oral communications between the main control room, the supplementary control rooms, other suitable plant locations and ofif-site emergency services are important to safety, particularly under conditions of anticipated operational occurrences or design basis accidents. Such conunuiucations should normally be provided with two, preferably diverse communication Unks and should be electromagneticaUy compatible with the I C systems (self-powered telephones, battery operated telephones, hand held portable radios). These communication links should be routed in such a way that fires, failures of electrical systems or other applicable PlEs cannot incapacitate both systems simultaneously. 

Information displays for monitoring accident conditions in the plant should be provided in the main control room and, as necessary, in the supplementary control rooms. 

Manual actuation. Manual actuation of the system should be possible from the main control room and if appropriate from the supplementary control room. 

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