The central control room (CCR) design is such that the station can be operated from the CCR during normal power operation, start-up and shutdown by one operator per unit and one control room super­visor. One assistant may be provided to assist on either a unit or station basis if necessary.

As far as possible, all unit controls and indications relating to start-up, normal power operation, shut­down and post-trip operation are mounted on the unit operator’s desk. Operational philosophy and space requirements dictate that some controls and indica­tions be mounted on vertical panels.

All other data required for commissioning, main­tenance, efficiency, administration or record purposes

T 13l E 2.14

display centre which is accessible from the CCR.

Each reactor/turbine unit has its own desk and vertical pane! on which is mounted conventional equip­ment for communication, display and control. A se­parate desk is provided for the supervisor which includes communications facilities, VDU displays to allow monitoring of unit performance, station services

DAO — Deaerator outlet

MSA — Methods for sampling and analysis

1C — Ion chromotography

EAAS Electrothermal (‘nameless’)

atomic absorption spectrometry

and electrical auxiliaries supply alarms. There are vertical panels for the cooling water system, station and reactor general services, fire alarms, station elec­trical system and high voltage switchgear system.

The layout of the room is shown in Fig 2.119. The desks and panels utilise the CEGB DIN modular design described in Volume F, Chapter 6. This modu­lar concept allows the desk layouts to be optimised

late in the construction programme to suit operating procedures.

The layout is based on the use of computer-driven visual display units (VDUs) as the primary source of information (i. e., data and alarms) and it is intended that normal power operation can be monitored and controlled from the centre section of the desk. Con­trols and indications are provided on the wings of the desk for less frequent operating regimes, i. e., start-up and shutdown.

Hardwired indications and alarms are provided to supplement the VDU displays, for the following

reasons:

• To enable the plant to be maintained at steady load without the computer system available.

• Where there is ergonomic advantage in having dis­plays directly associated with controls.

• To provide diverse indications where necessary to meet safety requirements.

• To safely shut down and monitor post-trip cooling without the aid of the computer system.

As a result of the extent of the post-trip cooling sys­tems, and the large number of plant state changes initiated by the eight sets of post-trip sequence equip­ment (PTSE) described in Section 8 of this chapter, the mimic has been designed to provide a functional overview of the state of post-trip cooling (Fig 2.120) and is mounted on the unit panel. In the short term post-trip, the operator is not required to monitor the detailed actions of the PTSE. He is required to es­tablish, with the aid of the mimic, that an adequate number of post-trip heat removal trains are operating and that reserves of coolant are adequate.