FISHERIES AND MARINE SERVICE. Translation Series No by O.M. Skulberg

Transcription

1 FISHERIES AND MARINE SERVICE Translation Series No. 3179»cuirvEs Biological effects of cooling water effluents from, nuclear power stations by O.M. Skulberg Original title: Biologiske virkninger av kj0levanns utslipp fra kjernekraftverk From: Teknish Ukeblad (Technical weekly journal), 121(20) : 52,54,58,62, 1974 Translated by the Translation Bureau(PMJ) Multilingual Services Division Department of the Secretary of State of Canada DepartMent of the Environment Fisheries and Marine Service Biological Station St. Andrews, N.B pages typescript

2 DEPARTMENTOFTHESECRETARYOFSTATE TRANSLATION BUREAU SECRÉTARIAT D'ÉTAT BUREAU DES TRADUCTIONS MULTILINGUAL SERVICES DIVISION CANADA. DIVISION DES SERVICES MULTILINGUES TRANSLATED FROM - TRADUCTION DE AUTHOR - AUTEUR Norwegian INTO - EN English O.M. Skulberg TITLE IN ENGLISH - TITRE ANGLAIS Biological effects of cooling water effluents from nuclear power stations. TITLE IN FOREIGN LANGUAGE (TRANSLITERATE FOREIGN CHARACTERS) TITRE EN LANGUE ÉTRANGÈRE (TRANSCRIRE EN CARACTÉRES ROMAINS) Biologiske virkninger av kjolevanns utslipp fra kjernekraftverk. REFERENCE IN FOREIGN LANGUAGE (NAME OF BOOK OR PUBLICATION) IN FULL. TRANSLITERATE FOREIGN CHARACTERS. RÉFÉRENCE. EN LANGUE ÉTRANGÈRE: (NOM DU LIVRE OU PUBLICATION), AU COMPLET, TRANSCRIRE EN CARACTÈRES ROMAINS. Teknisk Ukeblad REFERENCE IN ENGLISH - RÉFÉRENCE EN ANGLAIS PUBLISHER Technical weekly journal. ÉDI TEUR Norwegian Engineering Society. PLACE OF PUBLICATION LIEU DE PUBLICATION YEAR ANNÉE DATE OF PUBLICATION DATE DE PUBLICATION VOLUME ISSUE NO. NUMÉRO Oslo, Norway PAGE NUMBERS IN ORIGINAL NUMÉROS DES PAGES DANS L'ORIGINAL 52, 54, 56, 58, 62 NUMBER OF TYPED PAGES NOMBRE DE PAGES DACTYLOGRAPHIÉES REQUESTING DEPARTMENT MINISTà.RE*CLIENT Environment, TRANSLATION BUREAU NO NOTRE DOSSIER NC) BRANCH OR DIVISION DIRECTION OU DIVISION Fisheries Service TRANSLATOR (INITIA LS) TRADUCTEUR (INITIALES) pmj PERSON REQUESTING DEMANDÉ PAR Allan T. Reid YOUR NUMEIER VOTRE DOSSIER N 0 UN EDITUD DATE OF REQUEST DATE DE LA DEMANDE Feon TR A L'e U CT; F In 101 scukraent (R E V. 2/68)

3 DEIPARTMENT OF THE SECRETARY OF STATE TRANSLATION BUREAU MULTILINGUAL SERVICES DIVISION SECRETARIAT D'ÉTAT BUREAU DES TRADUCTIONS DIVISION DES SERVICES 1AUL7'I LIIvGUES CLIENT'S N0. DEPARTMENT DIVISION/BRANCH CITY NO DU CLIENT MINISTERE DIVISION/DIRECTION VILLE 3;nviron.men-t Fisi.leries Service Ottawap Ont. BUREAU NO. LANGUAGE TRANSLATOR (INITIALS) NO DU BUREAU LANGUE TRADUCTEUR ( INITIALES) Norwegian FI'iJ..f i^, ^.- Biological effects of cooling water effluents from nuclear power stations. Biologiske virkninger av kjçhlevanns utslipp fra kjernekraftverk. by Olav M. Skulberg Norwegian Institute for Water Research (NIVA) Gaustadalleen 25, Oslo 3 Teknisk Ukeblad, 121 (20) May 20, 1974, p.52, 54, 58, 62. It is important to evaluate all factors When establishing the site and construction of nuclear power stations, it is important to have a thorough knowledge of biological conditions in the immediate area as well as in the region. The degree and extent of effects on nature and the environment can to a large extent be controlled. This is - achieved by taking into consideration the hydrophysical and biological factors and assumptions in the choice of a location for the nuclear power station. It furthermore means that the planning and operation of the plant must be made with the conditions in the recipient in mind. This will at the same time make it possible to.reduce internal operational difficulties for nuclear power stations which are due to biological factors. in nature. without Biological research is always emphasizing the interaction and the totality We cannot affect a single species or component in the environment this having an effect on other species or the environment in total. Any encroachment on nature will, in addition to the intended effects, also have unintentional secondary effects. Throt.igh our manipulations of nature to obtain advantages of one kind or another unexpected changes can occur in nature which canrdirrn For i:^^o.;.,.:i... P.52 TIRAD;i`L.^i^i â^ib I':^ '' :; ` liâ4c SOS ^ lnfor+nf^licx^ sc^.11c1^^ ï:n, ''

4 : 2. could be unfavorable for society and the people affected. In some fields we have today a good knowledge of what happens when humans encroach directly in these areas. But side-effects are in most cases only known incompletely. This means that there need not be many combinations to consider before it is difficult to evaluate the complex of consequences that result. In our use and management. of natural resources, it is clear that there today is a lack of knowledge to guide developments so that they are environmentally and rationally as good as possible. It must also be taken into account that the resources are to cover the material and social requirements of future generations. Regarding the effects on nature and the environment of nuclear power stations it is important to judge them as a whole, if at all possible. Nuclear power stations and the effects on the recipient. Nuclear power stations can affect the recipient mainly by the release of radioactive substances and by thermally affecting the environment. The end products of the nuclear fission are mainly radioactive.with regard to half life they vary up to thousands of year.s. Highly radi.oactive waste must be stored, and materials with low radioactivity are usually released after having been reduced in quantity through treatment plants. The efficiency of nuclear power plants is relatively low. This results in considerable losses of energy as heat to the surroundings. Large quantities of cooling water are being used in nuclear power plants. The conditions in the United States can be used as a typical example. The consumption of energy has been doubled every tenth year. This means that in 1985 a quantity of water, corresponding in volume to about one ha-if the natural drainage of the continent, could be used for cooling water and heated 8-10 C. The biological and ecological consequences of the effect of heat is considered as perhaps the most difficult environmental disturbances that follow nuclear power plants. The cooling water recipients will react differently on the addition of heat, depending on natural conditions and pollution load. Rivers, lakes, estuaries and fjords will each present different problems. In Norway, only seawater recipients will be used due

5 Ç. 3. to geographical conditions, and the degree of access to the open sea will affect the type and degree of difficulties. The effluents from nuclear jpower stations must be included and judged as a whole together with other disturbances of the environment. How the operation of a nuclear power plant can influence the environment in the seawater recipient can be shown in a sketch. (Fig.1) Water is converted to steam with heat from an atomic reactor. The steam is led through a turbine which drives the generator for the production of electricity. The steam turbine operates with high steam pressure on one side and low steam pressure on the other. The low steam pressure is maintained in a condensator. Large volumes of cooling water are pumped from the sea 'through the condensator and are released to the recipient with a temperature of 8-10 C above the water temperature of the surroundings. The release of warm water is. the direct effect on the water environment in the area of a nuclear power plant. It is important to note that the cooling water is physically separated from direct contact with the atomic reactor. With proper construction and operation it is therefore only the content of radioactive substances in the cooling water which after storage and treatment by controlled methods has been added to the effluent water. Experiences from abroad show that there is a tendency to build bigger and bigger nuclear power plants due to technical and economical reasons. After gaining experience in one locality, several, nuclear power aggregates are often installed in the same location. When planning nuclear power plants, there are reasons for keeping this in mind with regards to evaluating the final effects on the cooling water recipient. When discussing the plans, an independent judgment of radiation ecological effects and thermal consequences must of course be obtained separately for each unit. Low-grade radioactive release with the cooling water. The radioactive waste products originate mainly from neutron activated corrosion products in the cooling system of the reactor and any fission products that may originate from leaks in the fuel elements. After preliminary purification and control of the quality and type of waste products, some of the active waste water is added to the cooling water stream.

6 _ Etekuisito it? Î LT.1. _ - Van n t ;,., I ;.e.' (-1, Pumpe Turbin Gene- \I:_ f AL:ILA U=77.:777,--ti -L -&--- ii l'-"j---- -'- ' Von,' Kondensotor \1nntokssii - Pumpe \ '., OISI;p CIV kjblevonn Kjelevonnsr esipient.. 7 e, Sjvonn Atomtecilitor Fig. 1. Sketch of cooling water system for a nuclear power station. Fig. 2 Lysenargi \-,en Karbondioksyd te vann Fotosynteso Respirasjon Organisk staff 44' oksygan Emegi F-1 0 rsi ca 4-) pg P Fig. 2. Both light and temperature affects the rfhotosynthesis. Fig. 3. Results of growth experiments with phaeodactylum trikornutum at various temperatures (10 C and 20 C and various phosphorus concentrations.

7 5. As the basic norms for regulating the permitted release of radioactive waste, most countries (perhaps all) use the recommendations given by the International Commission for Radioactive Products. (ICRP) The radioactive isotopes are taken up and concentrated by organisms and bound to sediments and can come in contact with humans via various routes. An important study would be to clarify the concentration of the. radioactive substances in the environment and in various organisms in order to find the most critical isotopes and any possible routes of transport back to humans. This would make it possible to calculate the capacity of a recipient with respect to receiving radioactive substances. In practice it has been shown that there are few technical problems involved in staying within the maximum permissible effluent release thereby calculated. For many existing nuclear power stations, the release is about one hundreth of the amount permitted. In some areas the radioactive substances will more easily come in contact with humans than others; either through internal exposure to radiation from radioactive isotopes accumulating in special nutrient chains and ending up as food for humans, or through exposure to external radiation from radioactive substances in certain areas (swimming beaches, fishing ear, etc.). With the technical possibilities available for controlling and reducing effluents, the recipients ability to receive radioactive substances will probably not be of great importance when choosing between several alternate locations. The point should be mentioned, however, that products from areas influenced by effluents from nuclear power stations could receive unfavorable publicity even if the level of radioactivity should not be demonstrably higher than in corresponding materials from other areas. Thermal effects on biological conditions. A cooling water flow of for instance 200 m 3 /s and with a temperature increase of 8-10 C will obviously affect a seawater recipient. These effects will be very much dependent on theproperties of the recipient and of how intakes and outlets are located. Evaluation of the magnitude of biological effects is dependent on knowledge of the temperature distribution in the seawater recipient that will occur when a nuclear power station has started operating. Thorough hydrophysical studies are therefore important prerequisites for the biological evaluations.

8 ." 6. The temperature is one of the environmental factors that has attracted greatest research interest and extensive data on the effects of temperature on various organisms are available both from laboratory experiments and from observations in nature. The temperature affects all chemical and physiological processes and generally results in an increase in metabolism - within certain limits. This can again lead to some indirect effects resulting in changes in the composition and quantitative occurrence of species in the system. The temperature has a deciding influence on the distribution of the species and will affect all stages of the life cycle of a species, for instance the migration of a fish, time and location for spawning, rate of growth and mortality. An increase of the temperature in the recipient can have both positive and negative effects as seen from practical utilization interests in the coastal areas in question. To predict in detail the biological effects in a recipient for the short or long term is almost impossible, but certain assumptions on the changes in the biological systems and changes in metabolisms could be given with, for instance, data from experimental studies. It would be very important for the biological effects to know if there will be continuous warm water effects or periodical breaks in connection with the operation of the nuclear power station. In the following sections, two areas of biological importance on the thermal effects in a seawater recipient are discussed. One area concerns fisheries-biological'conditions and the other pollution and eutrophication. Fisheries Tbiological conditions. The temperature is one of the factors that'create the limits of distribution for individual species. Very few species can live over the whole range of temperatures that occur in the ocean. Important functions are inhibited within certain temperatures so that the possibilities for a species maintain their Population are reduced. The temperature tolerance for fish is genetically controlled, but the ability to acclimatize is a non-inherited and reversible process. The ability to adapt to increasing temperatures is usually rapid (within 24 hours). It can, however, take from two to four weeks to adapt to a lowering of the temperature. Ecologically speaking, it is the rate of the acclimatization

9 7. process that is important, and sudden changes in the temperature of 6-8 C has been shown to be lethal for several species. Very often the range of temperatures where breeding (spawning) can take place is especially narrow. It is necessary to evaluate the whole spectrum of effects -for the p.56 fisheries, both direct and indirect effects. Direct effects can occur both through heating the water masses being used as cooling water and through radioactive effluents. Indirect effects can have consequences for commercial interest in the ocean areas. One example can be the effect on the fisheries in that important organisms in the food chain of the fish might be effected. A change in the time of maturation and hatching can result in a displacement in relation to the availability of food with disastrous consequences for the juveniles and the larvae which are dependent on a normal supply of food. There are many problems associated with evaluating the damaging effects on fisheries biological conditions. In general it is necessary to assume - that a nuclear power station will have negative effects on populations of fish species naturally occurring in the sea. It is a commonly held opinion that a temperature increase of about 1 C in a large area of the sea represents a considerable change in the water climate which could have farrea.ching biological consequences. effects would have to be long-térm studies. Studies to support the fisheries biological The possibilities of utilizing the heating effect from nuclear power stations for cultivating suitable species are interesting. Results from Norway and abroad (applied and research) clearly shows that there are good possibilities for utilizing the heated water. This would require special installations and the utilization of competent fisheries biologists. In connection with the development of the nuclear power programs in Norway,.it is important to keep these aspects in mind. They must also be taken into account when evaluating the location of nuclear power station. Pollution and eutrophication. Among the chief effects the various types of pollution have on the seawater recipient, are those grouped under the term eutrophication. Through physical and chemical effects, the environment for various organisms is changed and other species develop and thrive.

10 8. of It is first and foremost the loading/plant nutrients into the water masses that is the prime reason for eutrophication. A series of biological processes are thereby initiated which between the environment and the organisms living there. have consequences for the whole balance An extensive scientific literature is avilable on the nature and practical importance of eutrophication. The direct effect of temperature on the production of algae is complicated by the fact that photosynthesis (fig.2) consists of a light dependent process and of a "dark" temperature dependent process. This means that both light and temperature affects the photosynthesis. Other links in the plant synthesis of organic material can be affected by factors such as phosphorus and nitrogen compounds, iron etc. This further complicates the picture. Higher temperatures can only increase the production when other conditions are not limiting. The light is often limiting in the winter. The supply of plant nutrients can be limiting in the summer. The respiration is temperature dependent. It is doubled for approximately each ten degrees up to a maximum where it decreases sharply due to a breakdown in physiological processes. The photosynthesis also increases., towards a maximum when other factors are not limiting and the temperature dependence of the net production determine how these two processes change in relation to each other. Preliminary experiments with communities of organisms under various temperature conditions have been initiated at the Norwegian institute for water research. Seawater was pumped from 1 meter's depth into an experimental setup where it was led through 10 meter long troughs. One trough contains seawater with the same temperature as the fjord, two other contained seawater o o which was heated to C and 10 C above ambient respectively. The experiements showed that temperature increases in the water masses led to both qualitative and quantitative changes in the plant growth. When the temperature became too high, the growth stagnated. At a temperature of S o C above ambient the heat-loving green algae'entèromorpha dominated completely while the relatively rare brown algae Giffordia Sandriana dominated in the control trough. Furthermore, there were larger communities of bluegreen algae at S C temperature increase as compared to the control trough.

11 9. The results indicate that it is to be expected that benthic vegetation can be changed both qualitatively and quantitatively if the temperature in the water masses is increased. Studies have also been carried out on how the temperature affects the production in natural phytoplankton systems. These plants which are freefloating in the water masses, carry out most of the production in coastal waters. The results show that phytoplankton communities increase the production at increasing temperatures. During the experiments the production increased as much as 7%.per degree from 16.5 C, which was the surface temperature in Drobaksound, to 20.5 C. An important problem area is to assess how great effect any temperature increase will have in relation to the amounts of plant nutrients available for algae vegetation. Fig. 3 shows the production in algae cultures at two temperatures and at various phosphate concentrations added. Phosphate is one 6f the most important plant nutrients in water. At the-temperature of 10 C the rate of growth increased for the whole interval 0-22 pg phosphorus. The growth without the addition of phosphorus is due to storage in the cells of the algae. This is used for growth when the phosphorus content in the water is too low. At a temperature of 20 C the rate of growth from the addition of phosphorus only increased in the interval pg phosphorus. At a further increase of the phosphorus concentration, the growth rate was constant with a doubling time of about 14 hours. Inner Oslofjord is heavily polluted and eutrophication is strongly evident. The pollution is chiefly due to the content of plant nutrients in the sewage which leads to mass development of algae, especially planktonic algae. The organic material thereby produced is broken down in -nature by oxygen _ demanding process. Any addition of heat to the water masses in inner Oslofjord could increase the metabolism in the system. The organic material is thereby broken down more rapidly and the plant nutrients are more rapidly available for the phytoplankton. The total production of organic material would then increase. This would result in a higher consumption of oxygen and could lead to oxygen deficiencies in some areas of the fjord.

12 10. A temperature effect in an area already polluted could cancel cleanup efforts (removal of nutrient salts and organic materials) which might have been undertaken to protect the waters against such developments. To quantify the effects of a calculated temperature increase on the degree of eutrophication in a fjord is at the present time not possible. Biological evaluation'of*the'recipient.. Any recipient has its special combination of properties which makes it more or less suitable to receive pollutant loads. Results and experiences can therefore not be simply transferred from one area to another. It is therefore difficult to establish general norms for allowable loads. This applies especially to our geographical situation with large regional differences in natural conditions. With regards to the temperature effects, some countries have established norms for the maximum permissible temperatures or temperature increases in the effluent waters. regulations and exemptions Most of these apply to inland water courses and special from the norms are often given. Sonie countries have chosen not to establish rigid norms and criteria for the release of warm water effluents (Sweden, England and others). It is difficult to establish temperature limits at which it is assumed that damaging effects will take a jump either above or below certain limits. For some species limits can probably be set, but not for communities of organisms or for the collective ecological effect. In spite of the extensive knowledge available today on the importance of the temperature for marine organisms, it is not enough to recommend "definite" threshold values temperatures. for At the first evaluation of areas in which to locate a nuclear power station, it is logical to assume that there is a linear relationship between thermal effects and effects in the ecosystem. This means that the smaller the temperature increase and the smaller the àrea affected, the better. The following criteria apply when evaluating the actual recipients for nuclear power stations. * The effluents must not harm valuable biological resources or have an undesirable influence on the utilization of such resources in the area. The largest biological resources are today tied to the fisheries, but one must also count on protecting potential resources that could be

13 11. utilized in the future. * Shallow water areas are of great importance to the biological conditions in the ocean. Efforts should be made to avoid affecting coastal sections with large shallow water areas. * Effluents from nuclear power plants could magnify existing pollution effects in fjord areas. For that reason effluents from nuclear power stations should be located sonie distance away from the most heavily polluted recipients. * The estuaries of the large rivers are in a special class by themselves, both with regards to the composition of the organism community and as a connecting link between the sea and inland water courses. These areas are especially vulnerable and serve certain functions. The chances of. affecting migratory fish species further indicate that they should not be subject to loading. * Areas that should be protected from a scientific-ecological point of view should be affected as little as possible. The most important biological consequences of cooling water effluents from nuclear power plants can be summarized as follows: * Release of large quantities of warm water will change the temperature conditions near the release area. This will again affect biological conditions in the recipient (200 m 3 water/sec heated 10 o C is a lot of warm water. It corresponds in volume to 6.3 km 3 per year, a quantity that can be compared to the volume of the Oslo fjord inside Drobak,* which is 9.3 km 3.) * A temperature increase in heavily polluted (loaded) fjord areas will magnify the polluting effects already present. * The water which is pumped through nuclear power stations contains a number of organisms, for instance fish larvae which are too small to swim against the current in the intake. These organisus can be destroyed to various extents by heating, direct mechanical stress or toxic effects. (It is corninon practice to add chemical compounds to the cooling water in order to prevent fouling organisms from settling in the cooling water system).

14 12. * Radioactive and perhaps.toxic substances will probably be carried to the recipient by the cooling water from a nuclear power plant. These can. be taken up by organisms and cause damage. * If the cooling water is taken in at one depth and released at a different depth, the vertical exchange of water could increase. The surface water could then be supplied with increasing quantities of plant nutrients which could increase the growth of algae in the area.