is more relaxed.

2. Turbine building

The turbine building is located near the reactor building in order to optimize the main steam piping and feed water piping, based on consideration of the length and thermal stresses and keeping good accessibility and optimum cable length among the buildings.

There are various ways to arrange a reactor building and a turbine building as shown in Figure 2.2.6, including the T-, L- and I-arrangements. Both T- and I-arrangements feature the reactor building perpendicular to the turbine shaft and the I-arrangement places it in parallel. One basis for deciding the final arrangement is the protection philosophy towards a turbine missile in the site layout planning.

A multi-unit site is generally adopted in Japan and

Figure 2.2.6 Main building arrangements

turbine generator

in this case, the reactor building and the turbine building are arranged as shown in Figure 2.2,7.

Some operating plants or plants under construction in Japan have adopted either the slide-along arrangement or the mirror-image arrangement; the choice was made with due consideration for the location of the central control room and the overall view of the plant which depends on individual site conditions.

It is generally said that the slide-along arrangement has better accessibility than the mirror-image arrangement because of the nearly identical location of the plant equipment and facilities in the case of two adjacent main control rooms being in one independent building for two units.

Because of radioactive steam flow from the reactor to the turbine in a direct cycle BWR plant, the turbine facility becomes contaminated with

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radioactivity and its equipment and piping must be located in shielded reinforced concrete structures and the steam turbine and the steam intermediate stop valves must be covered by shielding of steel plate or reinforced concrete. The main turbine and generator are centrally located within the turbine building and they are supported by reinforced concrete pedestals of high rigidity. Steam condensers are located directly under the steam turbine and feed water heaters, various pumps and condensate de-mineralizers are located around the turbine pedestal and within the reinforced concrete shielding. The steam turbine generator total length, the main steam pipe routing at the front side of the steam turbine and the pull out space of the generator rotor behind the generator are the major factors that determine the length of the turbine building. The turbine building operating floor width is determined based on the space required to accommodate the disassembled equipment lay- down area, work space and passage during the outage of the plant Then, the horizontal dimension of the turbine building is determined considering the required spaces for the HVAC system and other auxiliary systems. The depth of the building to the operating floor is determined by the height of the condenser and turbine pedestal, and above the operating floor, the height of the low pressure turbine rotor casing, lifting height of this casing and the height of the overhead traveling crane location

are the determining factors.

The turbine building is located near the ocean as it needs a large quantity of sea water for cooling and in order to optimize the length of the circulating water piping from the circulating pump at the intake structure, it is placed nearer to the ocean in general. The condenser tube top height is normally set within a range where the siphoning effect of the ocean tide may be utilized in order to minimize the running cost of the large circulation water pumps.

Around the condensers, an ample space must be provided nearer to the ocean side for the condenser tubing pull out, and auxiliary equipment will be located nearer to the reactor building side. The steam that exits from the turbine condenses back to water in the condensers. The condensed water is pressurized by vertical condensate pumps that effectively utilize the suction head near the condensers and then it is transferred to the condensate de-mineralizer for filtering out impurities. The condensate filter has a hatch and a monorail above the de-mineralizer tower for ease of filter element replacement. The filtered condensate is re-heated in the feed water heaters which are long cylindrical horizontal heat exchangers and they need a pull out space for tubing replacement by cutting the cylindrical shells when the need arises. Some of the feed water heaters are placed within the condenser upper shell in order to utilize the condenser space, and to optimize the steam drain and extraction piping and to optimize the turbine building volume. The remainder of the feedwater heaters are then located on the floors near the turbine pedestal and reactor side. Because of high moisture contents in the steam that is fed into the feedwater heaters, they are located on a floor below the operating floor so that the extraction piping that goes through the condenser upper shell will have a downward slope for ease of draining. The pumps and feedwater heaters are fundamentally arranged to minimize the condensate and feedwater piping, considering the system flow, and to minimize the radiation to plant personnel by the separation of high radiation areas and low radiation areas and the shielding of the main passage for personnel with concrete walls.

The pumps, heat exchangers and blowers are arranged so that ample working space close to their

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