Power stations used on the CEGB system
Fig. 2.3 Kingsnorth 4 x 500 MW dual-fired station (see also colour photograph between pp 66 and pp 67)
2.2 Nuclear stations
The CEGB currently operates two basic types of nuclear stations, magnox and advanced gas cooled reactor (AGR), both of which utilise gas cooled reactor technology.
In both cases steam is raised in boilers which are heated by the reactor coolant carbon dioxide, but because a magnesium alloy is utilised as the fuel cladding for the early magnox stations, the steam
temperatures are limited. Similarly, the advanced .gas cooled reactor stations use carbon dioxide as a coolant, but by utilising a more advanced design of fuel element, higher steam temperatures comparable with the most up to date fossil-fired stations can be reached.
Nuclear power stations currently contribute base load generation amounting to over 16% of the total system capacity.
Figures 2.4 and 2.5 show Oldbury magnox and Heysham 2 AGR nuclear stations respectively.
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uebign^^na layout
Chapter 2
MW magno.x station uecn pp 66it nd pp 6")
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Fig. 2.5 Heysham 2 2*x 660 MW AGR station |
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2.3 Hydro-electric and pumped storage stations
The water resources of the IK Jo not allow for knee scale run-of-river hydro-electric stations, but a (e« small scale schemes have -een developed where thev
have been shown to be economic and environmentalb acceptable.
Chapte
Wald storage schemes have also been used wh
■'How sonic llc\ihilit\ i>| opei.iiion in iclalion to wj needs, hut again these have only been genciallv vial on a modest scale.
Figures 2.6 and 2.7 show the pumped storage stati
■ it flestmiog and the hydro station at Kicldi respectively.
HINKLEY POINT
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DUNGENESS
Fig. 1.9 Satellite imagery of thermal discharges from power stations
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(a) AIR CUSHION TRANSPORTER
Fig. 1.11 Transport of heavy or abnormal loads
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Fig. 1.12 Ash disposal site
Fig. 1.19 Hidden poyer: Dinorwig pumped storage power station
Fig. 1.20 View of Drax power station nearing completion
Fig. 1.33 Didcot toal-fired station landscape
MW coal-tiled siaiiun
Fig. 2.2 Littlcbrook D 3 x 660 MW oil-fired station
Fig. 2.3 Kingsnorth 4 x 500 MW dual-fired station
Fig. 2.4 Oldbury 2 x 313 MW magnox station
Fig. 2 7 KiclJcr 1 x 5 5 MW hvdro station
Fig. 2.S Cowes 2 x 70 MW
Fig. 2.9 Leicester 2 X 70 MW gas-turbine station
I’lG. 2.2f> Imbinc island concept
Fig. 2.67 View of pumphouse and intake screens — Littlebrook D
Power stations used on the CEGB system
Pumped storage power stations can offer an economic and flexible generation capacity where sites with suit able rainfall, geological strata and topography allow the construction of two reservoirs at different levels. These stations have a specific role on the CEGB system.
At off-peak periods cheap power can be provided from highly efficient base load fossil-fired and nuclear plant to pump water, through reversible turbines, up from the lower reservoir into the higher level storage reservoir. At times of peak or emergency demand the water is allowed to flow under gravity (as in a natural hydro-electric system), and its hydraulic head is used to generate power. By this means, improved use is made of the best thermal power stations in the system and power is provided at peak periods at a lower cost than that otherwise provided by less efficient power stations. The fuel which is saved, often more than offsets the additional fuel consumed in providing energy for the
pumping. The rc-usc of water allows a much greater generating capacity without increasing the civil engineering costs, which make up the bulk of the capital cost of pumped storage schemes.
In addition to providing a peak supply, the plant can also be used for standby duty since it can be ready for operation at very short notice to cover unexpected load increases, or breakdown elsewhere on the system.
Considerable flexibility is possible in planning storage schemes. The variables of pumped capacity, pumping periods and reservoir capacity can be con sidered together to give the most economical scheme when integrated with the system loading and the other plant in the system.
Because of its less complicated design, pumped storage can be built at a lower cost than conventional thermal power stations, and it needs only a small staff to operate it.
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