2. Equipment Arrangement

The equipment arrangement in the buildings of a typical single unit-type PWR plant and a twin unit-type PWR plant are shown in Figure 3.2.2. In a twin unit-type PWR plant, parts of the facilities are commonly used for the two reactor units. The equipment arrangement on the main floors of the reactor building, the reactor auxiliary building and the turbine building of a twin unit-type PWR plant and the cross-sectional view of these main buildings are shown in Figure 3.2.3 and Figure 3.2.4, respectively.

Descriptions of equipment arrangement in buildings of a typical PWR plant are given below.

1. Reactor building

The reactor building is the main building of the plant and contains the reactor containment (CV), the refueling system and so on. The reactor containment encloses the primary coolant loop components including the reactor vessel (RV), steam generators (SG) and reactor coolant pumps. The reactor containment is connected with the outside areas by a normal air lock and an emergency air lock, as well as an equipment hatch the level of which is matched to that of the main operating floor and of the access road. The reactor cavity, a stainless steel-lined concrete structure located above the RV, is filled with borated water. Operators perform refueling operations including fuel unloading from and reloading to the reactor core on the main operating floor.

2. Reactor auxiliary building

The reactor auxiliary building is adjacent to the reactor building and houses the equipment of the engineered safeguard systems including the safety injection system (SIS), the containment spray system (CSS), and the residual heat removal system (RHRS), the chemical and volume control system (CVCS), the waste disposal system (WDS), the heating, ventilating & air conditioning system and the sampling system in its radiation controlled areas, and the component cooling water system (CCWS), the on-site emergency power supply system, the electric and instrumentation systems of the safety systems, and the main control room and others in its radiation uncontrolled area. The main

structures of the reactor auxiliary building are made of reinforced concrete (partly steel-framed) and they are supported by the ground which has been confirmed to have sufficient supporting capabilities.

In principle, the areas for piping and components containing radioactive materials are located on lower stories in the reactor auxiliary building. Radiation exposures during the operation and maintenance of these items are reduced by routing the piping within radiation shielding walls, and installing each component in a separate and shielded room of sufficient space considering the ease of maintenance of the component.

Since the engineered safeguard systems are used to cool the reactor and the reactor containment during a reactor accident, they are located near the reactor containment. The safety related pumps, which intake the sump water in the containment building after an accident occurs, are located on a floor lower in its elevation than the lowest floor of the reactor containment vessel to assure sufficient NPSH (net positive suction head) values for the pumps.

The radiation uncontrolled areas for the equipment including the main control room and other electrical, instrumentation and control system equipment are located on an upper floor, which is convenient to control both the reactor system and the turbine-generator system and to reduce lengths of electrical cables and trays to connect these systems.

Occasionally, the emergency diesel generators are located in separate buildings. Access routes of inspectors for periodic inspections of their components, including the removal of the generators, need additional features provided for such cases. The air intake and discharge system equipment for the air conditioning and ventilation systems is located on the top floor of the building for the convenience of taking in fresh air and discharging contaminated air. The air intake of ventilation systems for the radiation controlled areas is located at a radiation uncontrolled area, while its discharge stack is located at a radiation controlled area,

3. Turbine building

The turbine building is a steel-framed structure

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NSRA, Japan

Main Buildings Arrangement Section

in Type Nuclear Power (Steel Containment)

@ Reactor Building

® Auxiliary Building

© Fuel Handling Building

© Turbine Building

® Main Control Room

® Auxiliary Component Room

(T) Reactor Vessel

2. Steam Generator

3. Reactor Coolant Pump

© Containment Polar Crane

© Refueling Crane

@ Turbine Generator

© Spent Fuel Pit

® Now Fuel Storage Area

Main Buildings Arrangement Section

PWR Single Type Nuclear Power Plant (Pre-stressed Concrete Containment)

Main Buildings Arrangement Plan

Figure 3.2.2 Main buildings arrangement (single type & twin type)

NSRA, Japan

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A

I

Figure 3.2.3 Buildings arrangement plan (3F)

30

ZE

40m

J

Fig. 3. 2. 4 Bui idings-Arrangement Section (A-A)

Figure 3.2.4 Buildings arrangement section (A-A)

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NSRA, Japan