(c) Industrial hazards The investigation of the poten­ tial ‘man-made’ hazards generally covers two areas; aircraft crash and transport and storage of hazardous materials. The study starts with a broad survey of potential hazard sources in the area such as industrial installations; rail, road, sea or pipeline routes along which toxic or flammable materials may be transported; airports and flight paths; and military training areas. This review identifies areas of possible concern that need more detailed study, for instance the passage of large tankers of liquid petroleum gas (LPG) past the site.

An assessment of the risk from these various sources can then be carried out to check that it meets the probability criteria. If it docs not, design modifications have to be considered. The layout of a nuclear station is such that materials stored on site do not present a hazard. However, where an additional station is planned for an existing site, it is necessary to check that the two stations will not become a source of hazard to each other.

It should also be noted that when considering an area for a coal-fired station, a careful stmlv must be made ol airfields (bolli commcicial and mililarv) with their associated flight paths that could be affected bv a future power station. Regulations to safeguard aircraft impose stringent restrictions on the height to which the buildings and chimneys and cooling towers can be built. At modern power stations, the heights of boiler houses often exceed 60 m, cooling towers are now 115 m and taller ones (up to 165 m) are currently being considered; chimneys can be up to 240 m in height.

(d) Ihqutlaiion distribution Information from the national censuses (carried out every ten years), from Local Authorities and from actual house counts is used to determine the distribution of population up to about 30 km from a potential nuclear site. Criteria have been established which place limits on the number of people resident within various distances of the site. Although these provide a set of guidelines against which to measure the acceptability of the site, they are not hard and fast rules. A site will only be licensed by the Nil if it is satisfied that the people living near to the site can be evacuated sufficiently quickly in the event of an incident and that the site is not too near to any large concentrations of population. Once a nuclear station has been established, restrictions on development are applied close to the site to ensure that the local population does not increase to an unacceptably high level.

2.4 Environmental considerations

There were two main statutory duties imposed upon the CEGB when it was formed in 1958:

Site selection and investigation

•To develop and maintain an efficient, co-ordinated and economical system of electricity supply.

•To take into account any effect which its proposals would have on the natural beauty of the countryside and on flora, fauna, features, buildings and objects of special interest.

The implications of this dual responsibility are far reaching. The CEGB has to reach a balanced judge­ ment for each development, one that seems the most appropriate in all the circumstances.

Planning a power station involves making an assess­ ment, at a point in time, of many technical, economic and social (actors. The CEGB has to draw up a balance sheet of costs and benefits which will range over the life span of the station. In a coldly impartial assessment, these factors would be quantified and reduced to present day values for comparison with price tags placed on the natural resources employed, including all aspects of amenity. But as no-one has developed a way of costing such qualities as natural beauty and tran­ quility, subjective judgements have to be made in ilrawing up plans. The CEGB has evolved methods of seeking and proving sites which make the best use of experience and new techniques; this includes a full input from national and local bodies, and there are opportunities for the general public to contribute their views. Following these initial consultations, the statu­ tory planning and consent -procedures to which pro­ posals are subjected ensure that they are adequately tested against the opinions, both of experts and of the general public.

For convenience, the environmental considerations may be grouped together as ecological, amenity and socioeconomic effects. In practice there are no defini­ tive divisions, measures taken to reduce one effect can have repercussions on another. For example, the instal­ lation of cooling towers would reduce temperature rises in the adjacent waters and changes in aquatic life, but at the cost of a visual intrusion.

2.4.1 .Ecological effects

The ecological effects can be defined as those factors which affect flora, fauna and human health. They are due to the physical occupation of land for the power station and for its construction, and to discharges from the site during both construction and operation.

As far as possible, the highest grade agricultural land, nature reserves or sites of special scientific interest would be avoided when selecting power station sites. However, experience has shown that providing the CEGB has taken the correct protective measures, power stations do not have serious effects on the use of adjacent land. For instance, farming can continue up to the station boundary, and the number of birds recorded in the vicinity of .some power stations has actually increased over the years.

19

Power station sitiricr'and site layout

Chapter 1

There are statutory controls over environmental pollution matters such as emission of solid particulates discharged through the chimneys of fossil-fuelled power stations, gaseous and liquid radioactive dis­ charges from nuclear power stations, the temperature of cooling water discharges, and noise. There is routine monitoring of these parameters and regular consulta­ tion with the controlling authorities (Government

Departments, Statutory Bodies	and	Local Authorities)
to discuss the regulations and	any	proposed changes
to them.		,

One example of a recent change involves recognition of a possible cause of acid rain requiring the installation of flue gas desulphurisation plant on new coal-fired stations and retrofitting on some existing stations, and also the introduction of low nitrogen oxide (NOX) burners.

Mathematical models have been developed for assessing the ground level concentrations of suspended particulate matter and gaseous emissions (e.g., SO2, NOX) derived from specified chimney heights under varying meteorological conditions. Such models allow the estimation of the chimney height required to satisfy stipulated regulatory guidelines for a given station

generating load pattern. The models have been vali­ dated against the results from field studies of the atmospheric dispersion of emitted chimney plumes. Wind tunnel facilities are also used for assessing the chimney plume dispersion problems which may be induced by neighbouring buildings or local topography.

Figure Ll3 shows diagrammatically the stages of chimney plume dispersion.

The effects of cooling water returned to the sea with increased temperature up to about !()"(’ above aiuhiem and low residual chlorine, have been examined exten­ sively. No discernible harmful effects have been found, indeed rather the opposite. It is a common feature of cooling water outfalls to find fish attracted to the warm turbulent water. Their presence attracts a wide range of seabirds which in turn attract ornithologists. At one station several million oysters are now flourishing in the warm water area around the outfall.

The effects of the cooling w’ater abstraction are likely to be limited to the immediate vicinity of the intakes. The amount of fish drawn in to suitably designed and located intakes has been found by experience to be not of commercial importance and only in estuaries where salmon are running has there been any justification for

NON • TURBULENT. RELATIVELY IMPERVIOUS LAYER:

1 -2km	------H-------	-d
	5 - 20 km	-100 km

DISTANCE DOWNWIND

The gaseous oxides ol sulphur and nitrogen in emissions from chimneys are dispersed by the wind. At whatever height they are emitted, from tai chimney stacks or

from ground-level sources, they become well mixed with the air after a few tens of kilometres. This is because of natural turbulence up to a kilometro or two above the ground. The atmosphere above that level is relatively imperviqus to emissions.

The gases may be lost by dry deposition as a gas at land and sea surfaces, or by wet deposition where the gases may be eftssohred in cloud droplets during the rain-forming process (rain-out) or be scavenged from the lower atmosphere by falling rain (wash-out). Solutions of sulphuric and nitric adds in rain win, of course, increase its acidity.

Ground level concentrations reach a maximum where the plume first touches the ground, usually within

5 > 20 km from the chimney and thereafter they progressively decrease. Mathematical models are used to predict these concentrations under varying meteorological conditions with different chimney heights.

Fig. 1.13 Stages of chimney plume dispersion

20

Site selection and investigation

any special measures. There has in fact been some success with mechanical means of recovering fish from the intake screens and returning them to the water source.

The location and design of headworks for both intake and outfall has to pay attention to fishery interests and the risk of local erosion or accretion or other changes to the sea bed. Experience has shown that headworks extending above the water level have only limited advantages and pose some structural maintenance

problems, as well as being noticeable features. There­ fore for future stations it is anticipated that the intake and outfall headworks will be below low water level.

The ecological effects caused by the construction of a power station can be reduced subsequently by restoring land which was used temporarily for construction storage areas. The CEGB has also set up nature parks and trails at some of its power stations. Figure 1.14 shows the layout and gives details of the Trawsfynydd nuclear power station nature trail in Snowdonia.

1 ■ Reception Centre amongst oak trees: views over the Llyn Trawsfynydd.

a man-made reservoir which provides cooling water tor the power station and water tor Maentwrog hydro-electric power station.

2 & 3. Hendre'r Mur and Gyfynys dams: great care was taken to ensure that their architecture harmonised with the station’s surroundings and many different species of tree were planted to give variety of form and colour to the grounds of the power station.

4 Rainbow trout hatchery: the trout reared in the warm water discharged from the station are used to stock fisheries in the reservoir.

The bund wait forming the cold water lagoon and the islands within the warm water lagoon provide nesting areas tor birds such as herring guHs, lesser black-backed gulls, great black-backed gulls, black headed gulls, terns and common sandpipers.

6- Nyrs Pandy Odwyryd is a stand ot beech and Scots pine where sparrow hawks, spotted flycatchers, green woodpeckers, willow warblers, carrion crows and buzzards have been recorded. There is aA important oak wood in Coed y Rhygen Nature Reserve.

" Maentwrog dam provides views down the ravine which contains many species

of plants, mammals and birds such as mosses and ferns, redstarts, warblers, dippers and bam owls.

11 Panoramic views ot countryside in the Snowdonia National Pa»k.

Fig. 1.14 Nature trail at Trawsfynydd power station in Snowdonia National Park

21

Power station siting and site layout

2.4.2Amenity considerations

Amenity can be defined as the conditions in the landscape that the public as a whole wishes to see and enjoy. It should be the aim of amenity planning to preserve or create these conditions. This is a daunting task, power-stations and transmission lines will always be seen from somewhere; most people dislike changes to the landscape to which they have become accus­ tomed, even if it is not of great value.

Buildings over 60 in high arc impossible to hide and so become new features in the landscape, but imagina­ tive architectural treatment and careful grouping of building and structures can help make what is seen, positive and acceptable. The preservation of existing woodlands, new planting (both on and off-sitc) and sometimes creating mounds from surplus excavated material can help to both conserve and create land­ scapes, and to reduce the areas from which the station can be seen. The C'F.GB commissions leading architec­ tural and landscaping consullants Io advise on these issues.

Nuclear stations have less visual intrusion than fossilfuelled stations as they have no tail chimneys, no large scale fuel stores, and offer greater opportunities for a compact development.

Direct cooled stations are less visually intrusive than tower cooled stations, and are often cheaper to build and operate. However, stations located on rivers and upper estuaries require cooling towers because there is insufficient water for direct cooling. The towers then represent a major visual feature because of their bulk. It is possible to develop layouts and architectural treatments for these large structural forms which can be considered as pleasing (and has led to Civic Trust Awards) by using all the devices of form, texture and colour available to the modern industrial designer.

Figure 1.15 demonstrates the major visual feature presented by the cooling towers at Drax power station.

In order to reduce the visual bulk of the cooling towers it is possible to use assisted draught rather than natural draught towers. This can result in lower or fewer cooling towers while still providing the same cooling performance as the natural draught towers. However, the resulting improvement in visual appear­ ance is not achieved without cost; there would be increased capital and running costs of the station mainly due to the provision and power consumption of the fans.

Figure 1.16 compares the relative sizes and quantities of the two types of cooling tower for a 2000 MW station.

The plume of water vapour that emerges from the cooling towers forms another problem of visual amenity that is more difficult to solve. There are no technical measures available which would significantly reduce the length of the plume. The length of the visible plume is determined by the prevailing meteoro­ logical conditions; the plume is short and wispy on

Chapter 1

warm sunny days, and long and dense on days of high humidity. It is fortunate that the latter condition usually coincides with dull overcast weather so that the plume tends to be lost from view against a cloudy background. The plume from an assisted draught tower would be denser than that from a natural draught tower. Dry cooling schemes would have no plumes; some such schemes have no towers, but they have the potential disadvantages of additional capital and oper­ ating costs and noise nuisance.

j he CLX>B also considers the cited of noise both from the power station and construction site as well as from local roads. Where appropriate, measures are taken to reduce noise nuisance, for example bv nr ' viding double glazing for affected houses.

The CEGB avoids valued feanires such as buildine-- of historic or architectural importance and conservation areas. Their existence can be established during the site investigations.

2.4.3Socioeconomic effects

More interest has taken place in recent years into the effects of large scale industrial developments on the local people. Studies are now carried out on the nature, magnitude and direction of the various socioeconomic effects on local communities which the construction of a new power station would have. These effects would occur in two stages; during the construction and during the operation of the station.

The overall construction period of about 7 years for a 1200 MW’PWR station and 5 years for a twin 900 MW coal-fired station is short relative to the 30 and -111 years respective lives of the power stations, but the sharpest local impacts may be experienced during the early construction phase. For example, one to two million tonnes of construction materials and fill may be brought to site together with a number of large and heavy loads. In the UK, most of the materials and plant required will be moved by road.

Other	traffic	will	arise from	the movement of
workers	to and	from	the site. It is	therefore necessary

to arrange with the Highway Authorities to improve roads, and on occasions build new roads to bypass urban areas at an early stage; usually with substantial financial contributions from the CEGB.

The total employment for a 1200 MW nuclear station is about 40 000 man years, of which about a quarter will be on site. While a substantial part of the site labour force may be within daily travel distance, there will be others who will move into the area. Studies are carried out to establish the availability and suitability of local skilled and unskilled labour. Predictions can then be made of the likely number required to be brought into the area, accommodation required and so on. Figure 1.17 shows the projected labour force for construction of a PWR power station.

Both the numbers of the labour force coming in and the local impacts from their arrival are difficult to

22 .

io	Fig. 1.15 Cooling towers at Drax power station
W	(see also colour photograph between pp 66 and pp 67)

investigation and selection Site

Power stationjyting' afttLsite layout

Unapter t

WITH S x 250 MW NATURAL DRAUGHT COOLING TOWERS

WITH 2 x 1000 MW ASSISTED DRAUGHT COOLING TOWERS

WITH 1 x 2000 MW ASSISTED DRAUGHT TOWER

Fig. 1.16 Comparison of cooling tower sizes

quantify. Experience shows wide variations from site to site depending on local conditions, on contract pro­ cedures, on personal preferences, and on whether a site hostel and caravan parks are provided. In planning to meet possible demands for accommodation and other services, including education for children, it is essential to maintain close contacts with the Local Authorities and to provide for staged development so that pro­ vision can be matched to demand. Lodgings and rented accommodation are commonly found within daily travelling distance of sites, but contractors have brought labour in daily from distances up to 50 km. Permanent power station staff tend to live close to the station but this depends on the relative availability of accommodation.

Other facilities provided during construction, such as improved potable water supplies, 11 kV or 33 kV electricity lines, and in at least two cases, new churches,

may remain for the use of local people, or they are removed if not wanted.

The long term effects of an operating station concern several areas; housing demands, travel patterns, expen­ diture distribution and effects on local employers.

The expenditure effects can be considered as money spent by the power station on goods and services, the rates paid by the power station and wages spent by employees. Revenue expenditure at power stations on goods and services, excluding fuel purchases, covers items ranging from plant spares to canteen food and carbon dioxide to telephone bills. Many items can only be purchased nationally or regionally and only a small percentage of the total can be purchased locally. Nevertheless, even these small expenditures can be significant in the local economy and some local businesses can benefit. There can also be some stimulus to the private house market as many power station staff

24

buy their homes, but these are distributed over a wide area.

The pattern of expenditure by power station staff in rural communities may be such that only a proportion of this income remains within the region, partly because more people have their own transport and do much of their buying at major shopping centres some distance away.

While local labour may be recruited it would usually be only a proportion of the total number employed at the station. Although some local employers would lose employees, studies have shown they would generally be spread over a range of businesses anil would probably not cause any local employer to curb his business activities. Some pressure may be brought on wage levels in rural areas; this may be seen as a good thing by the employees concerned.

When applications for stations have been submitted, tears have been expressed about the effects of the development on tourism and recreation. There is no evidence that this has a harmful effect, rather power stations of all tvpes attract visitors. As far as public lecie.ilioii is concerned the (ltd! has taken steps Io picservc exislim’, facilities, and where possible to enhance them. Examples are: the beach and grass

Site selection and investigation

covered sand dunes at Sizewell for public recreation; the creation at various stations of nature reserves, field study centres, bird sanctuaries; the licensing of fishing facilities and the establishment of fish farms for re­ stocking purposes, as distinct from the commercial fish farms making use of warmed cooling water discharges.

2.4.4Communication with local people

From the outset of site investigations the CEGB maintains a policy of open communication. The pro­ posed development is initially discussed with the relevant Statutory Authorities and othijr organisations with specific interests, to determine local conditions and matters for investigation. During consent applica­ tion these consultations are repeated in greater detail. Figure 1.18 shows the authorities with whom the CEGB consults on the local impacts of power stations.

In addition, public announcements are made of the intention to carry out investigations and later to apply for consents. This publicity with the information available, enables both individual members of the public, local societies and national bodies such as the Council for the Protection of Rural England and the Royal Society for the Protection of Birds to contribute

I-'ig. 1.17 Projected construction labour force at a typical PWR station

25

COUNTRYSIDE COMMISSION ROYAL FINE ARTS COMMISSION PLANNING AUTHORITIES LOCAL AUTHORITIES EXECUTIVE ARCHITECT LANDSCAPE CONSULTANT

NATURE CONSERVANCY COUNCIL

MINISTRY OF AGRICULTURE FISHERIES AND FOOD WAITH AU I MORI HTS

RESEARCH ESTABLISHMENTS STATUTORY POLLUTION CONTROL BODIES NATIONAL FARMERS UNION

GOVERNMENT DEPARTMENTS

LOCAL AUTHORITIES

HEALTH ANO SAFETY EXECUTIVE

NATIONAL FARMERS UNION

Fiii. 1.IS Consultations on local environmental impacts

and comment if they wish to the CEGB and/or to the Planning Authorities. The CEGB has in fact under­

taken to	produce formal environmental statements for
all future	power station proposals. If it is necessary,

a public inquiry will be held. The CEGB provides evidence and witnesses and the case is given the most critical scrutiny by the objectors, as shown by the inquiry for Sizewell B. Local meetings are held during the planning, construction and operation stages.

2.4.5Assessment of environmental effects

In order to predict the changes to local conditions brought about by a power station, it is necessary to find out what the existing situation is; to identify those factors which arc sensitive and to predict how they will be affected.

The CEGB employs its own technical and environ­ mental specialists as well as having planners and designers who are practised in seeking better solutions based on information fed back from monitoring the effects of previous stations.

The CEGB has worked for more than 25 years on fundamental and applied research into environmental impacts, particularly into the ecological factors. The wide range of problems set by a diversity of sites with different environmental conditions, has resulted in the accumulation of knowledge which can be used to estimate, with some precision, the effects of further power stations on existing or new sites.

Equally, the CEGB is alert to new techniques or methods that may be adopted, and to relevant work being done elsewhere in the world. Recent examples are the use of mathematical models for predicting cooling water dispersion and the efforts to set up satisfactory ecological models, the use of computer graphics for the presentation of hydrographic informa­ tion and in visual intrusion studies. Satellites have been 'of only limited use to date in giving information on geological faults when considering seismic conditions.

However,	they	might provide	more information	in
future on	such	matters as the	surface patterns	of

warmed water. Spray cooling as an alternative to cooling towers has been tried in the USA but experi­ ence suggests that this is unlikely to be applicable in this country.

Experience		of	considering		environmental impacts
and	consultation		with the Statutory				Authorities	helps
in	the early	recognition		of	where	significant		effects
may occur and			enables	resources		to	be concentrated

on studying them. Experience also guides efforts to improve and to create better conditions; but perhaps nowhere is experience more useful than in the very difficult task of forming a balanced judgement on what combination of various environmental impacts would be acceptable. Some can be estimated with precision, such as the loss of agricultural land. Others such as noise levels, can be scientifically predicted; but people’s perception of noise nuisance differs. Factors like visual intrusion are largely subjective and even

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