AECL-4767

ATOMIC ENERGY OF L'ENERGIE ATOMIQUE CANADA LIMITED DU CANADA, LI MITE E

THE CANADIAN NUCLEAR LE PROGRAMME NUCLEO- POWER PROGRAM ELECTRIQUE DU CANADA

A Brief to tiie Science Council of Canada Me'moire soumis au Conseil des Sciences Submitted December 1972 du Canada en decembre 1972

Chalk River, Ontario

April 1974 avri! THE CANADIAN NUCLEAR POWER PROGRAM

A BRIEF TO THE SCIENCE COUNCIL OF CANADA*

Submitted December 197i

Chalk River, Ontario, April, 1974

AECL-4767

* Previously issued as Atomic Energy of Canada Limited Unpublished internal Report CRNL-K9(>. December 1972. The Canadian Nuclear Power Program A Brief to the Science Council of Canada*

Submitted December 1972

ABSTRACT

Canada has a commercially viable and extremely successful nuclear power reactor program that has assured its position among those advanced nations that are reaping the benefits of the peaceful exploitation of nuclear power. This Brief describes the Canadian program and relates it to the world picture of nuclear power development, ii also traces the Canadian program through its present status to the long-term options that will maintain its position as a source ol very low cosl electricity. < - •' ,.. ,

Chalk River, Ontario April 1974

Al-;Cl.-47(,7

* Previously issued as Atomic Energy of Canada Limited Unpublished Internal Report CRNL-896, December 1972. Le programme nucléo-électrique du Canada

Mémoire soumis au Conseil des Sciences du Canada en décembre 1972*

Résun *!

Le programme nucléo-électrique canadien comporte des centrales nucléaires économiquement viables et fonctionnant à merveille. Ce programme range le Canada parmi les nations avancées sachant tirer parti de l'exploitation pacifique de l'énergie nucléaire. On décrit le programme en question et on le compare aux développements nucléo-électriques des autres pays. Enfin, on envisage son évolution vers des options à long terme qui consolideront la position des réacteurs CANDU comme sources d'électricité très bon marché.

L'Energie Atomique du Canada, Limitée Laboratoires Nucléaires de Chalk River Chalk River, Ontario

April 1974

AECL-4767

* D'abord publié comme Rapport interne de l'EACL, sous le numéro CRNL-896 (Décembre 1972) CONTENTS

Pag*

1. Introduction 1

2. Knerg> Needs 1

•I. Nuclear Power 3

4. CANDU-PHW Rearlorr, 7

5. Advanced CANDC Reactor Options 12

6. Fuel Cycles and Fuel Utilization 14

7. Long-Term Options lti

8. Common Problems -')

9. Specilif Canadian Considerations '-2

10. Summarj' of CANL)'.J IJ

11. Rt.'latpd Considerations -•'

1 2. Keferrns-es . ;i! 1. INTRODUCTION its simplest form, the forecast energy demand (Figure 1) is the product of two terms: This Brief provides a status report on AECL's* — the world's population, and applied research, development and utilization pro- gram on nuclear power and attempts to fit this into — the energy per capita. the world picture. To provide a frame of reference The predictions^'^'") assume that the present some data are included on topics of which AECL has "population explosion" cannot continue indefinitely no claim to specialised knowledge, e.g., energy ?.nd that some means will be found to provide a reserves and requirements. levelling off at 15 billion. It is further assumed that It contains summaries of and references to the the average energy per capita throughout the world technological information, rather than a discussion of by that time will be about five times the present the issues raised in the correspondence relating to the average for the USA and Canada. Science Council Energy Study. However, these issues are referred to with sufficient adequacy to enable further, mere detailed, information to be requested as required. The Brief also attempts to demonstrate that the AECL nuclear power program satisfies the criteria for a major project related to science policy. That is to say, it: — is socially responsible — has major Canadian innovative content Q/YEAR — involves the transfer of technology to industry as an integral part of the program — is beneficial to the national economy — is competitive internationally on the quality of the work.

2. ENERGY NEEDS

Global 2100

The world's demand for energy continues to grow Figure 1 - Projected world energy demand from all sources. (O • at an ever-increasing rate and the eventual exhaustion 1018 BTU ~1021J> of conventional energy sources is now within sight. In

* AECL— Atomic Energy of Canada Limited 200 000

100 000

50 000 NOTE: FROM 1957 - 1971 FROM 1972 - 1978

MW(e) Installed 1957 11621 Nuclear Power 1958 15594 Capacity 1959 21141 26848 MW(e) 1960 1961 48774 1962 71683 1963 92649 1964 118700 ESTIMATED 1965 148061 I 1966 172614 I 1967 189743 )

1960 1965 1970 1975 1978 YEARS

Figure 1a — Actual and projected world nuclear power capacity. (Power and Research Reactors in Member States — 1972 Edition, International Atomic Energy Agency, Vienna, 1972)

PRODUCTION |10' BABREIS PER YEAR! Figure 2 — Estimates of world oil production, indicating magnitude of uncertainty. (Scientific American, 225(3), p. 69, September 1971)

I900 1935 1050 W7J 3000 2025 20.50 2075 2100

Figure 3 - Estimated world coa! production, indicating magnitude of uncertainty. The broken 20 | curve shows the trend if production were to con- PRODUCTION I O9 METRIC TONS tinue to rise at the present rate of 3.56% per year. PER YEAR) Coal mined and burned to date is shown shaded. (Scientific American, 225(3), p. 69, September 1971)

1900 2000 2100 2200 2300 2*00 2500 2600 The actual and projected growth of world nuclear the thermal stations is coal imported from the USA power capacity is shown in Figure la. Figure 2 shows and the predicted demand is such that, were it. not for that oil (and hence natural gas) production is nuclear power, $300 million per year would be spent expected to decrease from about the year 2000 and on US coal by 1980. Similarly, New Brunswick is Figure 3 indicates that coal production is likely to considering the importation of oil to generate and pass through a similar peak by 2200. The depletion of export electric power. these resources and an increasing requirement for As a whole, Canada is exceptionally well endowed pollution control will force up the cost of energy with both fossil and nuclear resources, having rela- from fossil fuels. Most of the economically accessible tively plentiful reserves of coal, petroleum and hydro-electric capacity is already tapped and the natural gas, about one fifth of the world's uranium remaining sites are not significant in the overall reserves and comparable amounts of thorium^). On a picture. Tidal and reothermal power do not offer per capita basis Canada has much more uranium than appreciable contributions. Solar power is sufficient the USA, a fact Lhat may help to explain some for all needs, but that it can be harnessed econo- differences in the nuclear power programs of the two mically seems most improbable. countries. Unlike fossil fuels, nuclear fuels are avail- Nuclear power provides the only known means of able throughout the country at an insignificant cost reconciling the world's energy demand with what is differential. If nuclear fuel were produced in Halifax available. Already, 28,365 MW(e) of nuclear power is and consumed in Vancouver, shipping the fuel, even operating throughout the world and a further by air freight, would contribute less than 0.03 216,185 MW(e) is committed (Table 1). In Section 6 m$/kWh. In the past, some regions have benefited we will show that the world contains enough uranium greatly from having available low-cost hydro-electric and thorium to satisfy all nuclear fuel requirements power. Now nuclear power offers the reality of for centuries. The possiblity that some completely low-cost power without these regional disparities. new energy source will be discovered cannot be if Canada, as an affluent nation, wishes to aid dismissed. However, we should recognize that, for third-world countries, CANDU (Canada Deuterium any major technology, the period from initial concept Uranium) reactors could be made available to them. to large-scale commercialization is at least 30 years. Abundant electric power would be of inestimable Thus, we must do the best we can with what we s r value and, for reasons that will be given later (Section already have until at least the 21 ' century. 11), the CANDU system is uniquely suitable for a developing country. Canadian Canadian energy demands to the year 2000 have 3. NUCLEAR POWER been estimated' ' for the various fuels. For the year 2000 the predicted needs, as ratios of the actual 1970 Nuclear power can be obtained from two reac- values, are 5 times for coal, 3 times for petroleum, 4 tions, fission and fusion. Since the feasibility of times for natural gas, 6.5 limes for electricity and 50 controlled power from fusion has not yet been times for uranium. demonstrated, it will be considered later under Within Canada there are oovious regional varia- long-term options (Section 7). The heat released tions in energy resources. For instance, Alberta, with during the decay of radionuclides can be converted to large reserves of fossil fuels, has no immediate fear of electricity and, strictly, this too is nuclear power. The an energy shortage. Ontario has no significant fossil Commercial Products group of AECL is using radio- fuel resources and is already exploiting all major active cobalt, a by-product of electric power from the hydro-electric sources within convenient reach of Pickering reactors, to provide highly reliable, long- load centres. Quebec and British Columbia are still lived power sources for unattended equipment in harnessing hydro-electric power, but at the expense remote locationst6'7'. However, the total power rrom of increased transmission line costs. The transporta- such sources is insignificant in thp present context. tion of coal by water routes is a much cheaper means Thus, at present, the fission reaction is the only of transmitting energy, but this very fact introduces a means of achieving nuclear power. new problem. For some years now Ontario has been building thermal generating stations to supplement The nuclei of certain isotopes of heavy elements the hydro-electric ones. The cheapest fossil fuel for become unstable on capturing a neutron. The TABLE 1 Existing and planned world nuclear power ger.evating capacity by country and reactor type. (Compiled from data in "Power and Research Reactors in Member States", 1972 Edition, IAEA, Vienna.)

Country Reactor Installed Planned or Type3 Capacity Under Construction (MWe) (MWe)

Argentina 4,7 919 Australia 7 500 Austria 1 692 Belgium 2 1,650 Brazil 2 600 Bulgaria 2 880 Canada 4 1,479 4,024 Czechoslovakia 2,4 1,730 Finland 2 1,480 France 2-5 2,683 3,550 Germany, Fed. R. 1-4,6 2,179 22,883 Hungary 2 880 India 1,4 380 800 Israel 7 400 Italy 1-4 597 790 Japan 1-5,7 1,285 17,880 Korea 2 564 Mexico 7 600 Netherlands 1,2 53 450 Norway 7 500 Pakistan 4 125 Spain 1-3,7 1,073 6,530 S. Africa 7 500 Sweden 1,^,7 440 8,700 Switzerland 1.2,7 1,006 4,750 Thailand 7 500 U.K. 3-5, 7 4,991 14,750 USA 1~3,5 10,041 109,552 USSR 1-3,5 2,014 7,930 Yugoslavia 7 1,200

a Reactor type: 1 — Boiling light water 5 — Breeder 2 - Pressurized light water 6 - LWR 3 — Graphite moderated 7 — Not announced 4 — Heavy-water moderated fissile plutonium-239 and uranium-233, respectively. Thus, neutron capture by fissile and fertile materials is essential to the production of nuclear power, while •-O + ~200 MEV all other neutron losses are undesirable and have to be o — minimized. NEUTRON O Figure 5 shows schematically an idealized arrange- FISSION NEUTRONS ment for harnessing this nuclear power. Fuel rods PRODUCTS containing fissile material, separated from natural Figure 4 - Simplified diagram of the fission reaction. (Scientific uranium in an "enrichment plant", form the central American, 225(3), p. 67, September 1971) region of a reactor core. Surrounding them is a region of fuel rods containing fer'lie material in which new resulting process, fission, produces energy, two fissile material will be generated. A forced-circulation "fission product" nuclei and two or three neutrons, coolant transfers heat from both forms of fuel rod to one of which can be used to continue the "chain a he.it exchanger, after which conventional means are reaction" by absorption in another fission nucleus employed to generate electricity. (Figure 4). For practical purposes, uranium-235 is the This highly simplified design provides a fair idea of only naturally occurring fissile isotope, and its abun- the principles of "fast reactors", so called because the dance in uranium is only 0.7%. However, new fissile neutrons ate not appreciably slowed down by atomic material is produced when nuclei of "fertile" isotopes collisions in the reactor. Thus the neutrons are highly capture neutrons. In this way fertile uranium-238 and energetic, having speeds roughly the same as those thorium-232, the preponderant naturally occurring with which they are released in the fission process. isotopes of uranium and thorium, can be converted to The feasibility of fast reactors has been demonstrated but there are many practical difficulties in harnessing STEAM them to provide economic power. Since there is GENERATOR STEAM worldwide agreement that nuclear power will not be REACTOR HEAT \y EXCHANGER available commercially from fast reactors until at least the mid-1980s they will be considered further FERTILE BLANKET under long-term options (Section 7). At present, all commercial nuclear power comes FISSILE, CORE from "thermal reactors", in which the fast neutrons are slowed down to thermal energies by multiple FUEL collisions with a "moderator" before being allowed to RODS react with the fissile or fertile materials (Figure 6). The relative capture cross section of uranium-235, LIQUID METAL (SODIUM) compared with that of uranium-238, is very much WATER greater for thermal than for fast, neutrons. Thus, LI QUID-M ETAL-COOLED moderating the neutrons tends to compensate for the FAST REACTOR low natural abundance of uranium-235. Indeed,

Figure 5 Schematic diagram of a fast reactor to produce power. e--

Figure 6 - Neutron moderation and balance in a thermal reactor. neutron moderation opens up the possibility of tuted for carbon dioxide to allow higher coolant obtaining nuclear power from natural uranium as a temperatures. These reactors have high thermal fuel, i.e., without the expense of enriching it in the efficiency and a possibility of low fuelling costs. uranium-235 isotope, although this capability is not Light-Water Reactors (LWRs). Most power reac- exploited in all thermal reactors. tors now being constructed are the US-developed The moderator is therefore a very important reactors in which both moderator and coolant component of any thermal reactor. It must slow consist of light water and the whole core is down neutrons efficiently while capturing as few as contained within a pressure vessel (Figure 8). Their possible. Both requirements are factored into the moderating ratio, a sort of figure of merit for moderators. Table 2 shows that, of the potential TABLE 2 Merit rating of potential moderators materials, heavy water (D20 or deuterium oxide) is outstanding as a moderator. Moderating Ratio In designing a practical thermal reactor, three fundamental selections have to be made: Zirconium Hydride 49 Moderator material. Table 2 indicates the practical Organic Liquids 60-90 possibilities. The difference between solid and Light Water 72 liquid moderators obviously affects the engi- neering design of the reactor. Beryllium 159 Graphite Coolant material. Coolants considered have in- 160 cluded heavy water, ordinary (or light) water, Beryllium Oxide 190 gases such as carbon dioxide and helium, organic Heavy Water pure 12.000 liquids, liquid metals and fused salts. 44.8 atom '.V 2300 Form of coolant containment. The hot coolant is at an elevated pressure and must be contained. The fuel, too, must be within the coolant containment, TABLE 3 Canadian power reactors — operating or but the moderator can be either inside or outside. under construction For the former the whole reactor core is within a single, large, thick-walled pressure vessel, while for the latter, multiple, relatively small-diameter, Type MW(e) Name Start-up thin-walled pressure tubes pass through the mode- rator. PHW 22 NPD Rolphton 1962 Other important choices have to be made, for PHW 208 Douglas Point 1967 instance the fuel cycle (Section 6), but these three PHW 125 KANUPP 1971 factors determine the major physical characteristics of thermal reactors. PHW 508 Pickering-1 1971 In practiced), three combinations of these factors BLW 250 Gentilly 1971 have been developed to the point of commercial PHW 508 Pickering-2 1971 viability: PHW 203 RAPP-1 1972 Gas-Graphite Reactors. In these reactors, pio- PHW 508 Pickering-3 1972 neered in the UK and France, the moderator is

graphite, the coolant is gas (originally CO2) and PHW 508 Pickering-4 1373 the whole core is within the coolant containment PHW 203 RAPP-2 1974 (Figure 7). In the original model of this type of PHW 750 reactor the thermal efficiency was low, neutron Bruce-1 1976 economy poor, and capital cost high. Later models PHW 750 Bruce-2 1977 of this reactor type have high thermal efficiency PHW 750 Bruce-3 1978 but are still not competitive on the world market. PHW High Temperature Reactors (HTRs) are currently 750 Bruce-4 1979 being developed, in which helium has been substi- STEAM GRAPHITE GENERATOR STEAM MODERATOR STEAM WATER MODERATOR & COOLANT

STEAM GENERATOR FUEL

REACTOR WATER

BLOWER PRESSURIZED-WATER REACTOR GAS COOLED REACTOR (LIGHT WATER)

Figure 7 — Schematic diagram of a gas-cooled, graphite- Figure 8 — Schematic diagram of a light-water-cooled, pres- moderaied reactor. sure-vessel reactor.

thermal efficiency is relatively low; their capital Pakistan. All except one (Gentilly — to be discussed cost is also low, but their fuelling costs are high. in Section 5) use heavy water as coolant and are Because of their widespread accep lance they are known as CANDU-PHW (for Pressurized Heavy- usually laken as the basis for economic compari- Water) reactors. sons with other reactor types. Although all CANDU-PHW reactors follow basi- Heavy-Water Reactors (HWRs). In heavy-water cally the same design, each fulfills an individual and reactors the moderator is heavy water and, in valuable function in bringing this type of reactor to practice, the coolant is usually contained in its present competitive position, and in developing its pressure tubes (Figure 9). Various coolants are future potential: possible (Section 5) but at present the only commercially available versions have either heavy or light water as coolant. CANDU reactors are the best established examples of heavy-water reactors, STEAM TO TURBINE which are also marketed by the UK and Germany X and are being developed by Japan, India, and Italy. PRESSURE STEAM The present generation of CANDU reactors is TUBES GENERATOR FUEL discussed in Section 4, and projected advanced iREACTOR options in Section 5. HEAVY WATER COOLANT •i. CANDU-PHW REACTORS

Already Canada has 2115 MW(e) of nuclear power operating and a further 3500 MW(e) under construc- tion. Over the next twenty years our installed nuclear MODERATOR PUMP capacity is expected to grow rapidly, reaching 8000 MW(e) by 1980 and 35,000 MW(e) by 1990(9-10'11). n • • tJtf WATER FROM The major commitments to date have been made by PHVW CONDENSER Ontario Hydro, in whose system nuclear power now (Pressurized Heavy Water) accounts for about 14% of the total generated. Table 3 lists all CANDU reactors, operating or under Figure 9 - Schematic diagram of a heavy-water-cooled, pres construction, including two in India and one in sure lube reactor. Nuclear Power Demonstration (NPD) Reactor(12'13). As befits a prototype, the greatest value of the The NPD reactor developed all the basic technologies Douglas Point reactor has been in showing how future for CANDU-PHW reactors and when it came into reactors could be improved. Several lessons, learned operation in 1962, it demonstrated the viability of the hard way, proved invaluab'e in the design of the the CANDU-PHW concept. All CANDU-PHW reactors Pickering and Bruce reactors^), notably in employ on-power refuelling and, until NPD was connection with: operating, the feasibility of this sophisticated proce- — designing to reduce heavy-water losses, and dure could be questioned. Over the years, a careful accounting of the fuel consumed and power produced — minimizing activity fields that impede mainte- has substantiated the reactor physics calculations for nance of the primary coolant circuit. this type of reactor* 14>. NPD is still operating and, in Finally, the exceptionally smooth commissioning of addition to producing power for Ontario Hydro, the Pickering reactors is largely attributable to the serves as a training centre for future electrical utility experience gained by Ontario Hydro staff in operating staff. It also acts as a test-bed for new operating the Douglas Point reactor. designs of fuel and as a vehicle for other aspects of our experimental program. For instance, a few y&ars Pickering Reactors! 1'). These reactors (Figure 10) ago, it was converted from single-phase to two-phase represent the first commercial application of coolant. The purpose was to determine whether CANDU-PHW reactors and their striking success allowing the coolant to boil, as proposed for future confirms Canada's ability to carry through a major CANDU-PHW reactors, would introduce any innovation to its realization. Pickering in fact proves unexpected problems. that Canada has the necessary scientific, engineering and industrial bases for a sophisticated technology. Douglas Point Reactor(i5). The Douglas Point reac- Pickering's first unit went critical in February tor was committed before NPD was operational. It 1971 and within three months had reached full was designed to be large enough to be a prototype for power. Although the first-critical date was almost two commercial CANDU-PHW reactors, and its perfor- months behind the schedule set in 1967, the time mance has been similar to that of most other needed for commissioning was so short that unit 1 prototype nuclear power plants in the world. For the was accepted into service one month ahead of last two years its capacity factor has averaged about schedule. This performance was highly satisfactory, 5U'V, but during the 'vinter months it has been a but was bettered successively by units 2 and 3. To reliable power source, achieving an SOS; capacity bring such complex plants to full-power in periods of factor last winter. At least half its unreliability has 100 days or less is a very significant achievement. The been associated with standard power station com- period from first electricity to in-service acceptance ponents such as valves, seals, turbines and generators. averaged 2'-i months for the first three Pickering This experience provided early warning that we couid units, compared with an average of 3'/i> months for not take these components for granted. Ontario Hydro's four 500 MW(e) coal-fired units at Lambton. According to Nucleonics Week(l^), there is The operation of the Douglas Point reactor has nothing to compare with this experience elsewhere in confirmed the reactor physics calculations and has the nuclear world except, possibly. Commonwealth further demonstrated the capability of routine on- Edison's Dresden-3 and Quad Cities-1 with pe.-iods of power refuelling. At one time as many as 20 fuel three and two months, respectively, for individual channels per week were being refuelled, compared units. Since Pickering units 1 and 2 were declared with the required average of 10 per week. A major "in-service" by Ontario Hydro, they achieved average advantage claimed for CANDU-PHW reactors is their capacity factors of 85% and 87%, respectively, up to very low fuelling costs (see Section 6). The operation the end of June, 1972, when they were shut down by of the reactor has shown not only that the estimates a strike. are realistic but also that the fuel is highly reliable. Less than V'i, of all fuel loaded into the reactor has At a more detailed level, perhaps the most failed. A recent decrease in the failure rate (only one important experience gained to date from Pickering fuel assembly has failed in the reactor since the start relates to heavy-water management. The total upkeep of 1971) can be attributed to changes in the fuel costs (the sum of irrecoverable losses and recovery management schedule and to improvements in the costs) for units 1 and 2 decreased quickly as fuel. commissioning was completed and both units have mEH cooi AN' | ""'_' 1_~ MOL't (AIOH1 • AST w,

L 1 *KF will!

Fiyui^ 10 —Ontario Hydro's Pickering Nuclear Gene Mting Station on Lake Ontario, near Toronto, con- sisting of foui 540 MW(e) renclois.

operated well below the design target of 1.3 kg RAPP Reactors(24). The situation in India is appre- D2O/h per reactor, equivalent to 0.15 m$/kWh. This experience shows that the Pickering reactors had ciably different from that in Pakistan, in that India is indeed profited from the lessons learned at NPD and responsible for the construction of these two reactors Douglas Point, and that heavy-water upkeep need of Canadian design, with AECL acting as consultant. contribute no more than about 0.1 m$/kWh to the It is the Indians' avowed intent to increase the Indian cost of the power. Up to this point CANDU-PHW manufacturing content in each successive reactor and reactors had been susceptible to the criticism that they have committed further CANDU-lype reactors such a low allowance was unrealistic for a commercial for construction independently of Canadian assis- plant. tance. They are already fabricating their own fuel and calandria tubes. These facts show that the CANDU Bruce Reactors^9'2**). The four-reactor Pruce sta- system is particularly suited to countries that wish to tion incorporates some evolutionary improvements manufacture an increasing fraction of their own and certain design changes necessary for a power power plants as their industrial base strengthens. output 50% greater than that of the Pickering International Marketing. Canada has bid on contracts reactors. Some simplification of the detailed engi- to construct nuclear power reactors in six inter- neering is expected to further reduce heavy-water national competitions. In four of these, none of the losses and to facilitate maintenance. bidders was awarded a contract and the project was KANUPP Reactor(21). The KANUPP reactor was postponed, while in the most recent one, for constructed and commissioned in Pakistan by the Argentina, the bids are still being assessed* This Canadian General Electric Company Limited under a experience has shown CANDU reactors to be compe- fixed price contract. Its major significance to the titive on world markets, both technically and CANDU system is in showing that a Canadian economically. For instance, in Australia, the CANDU company can successfully undertake a project of ti.is reactor was in the final short-list and in Mexico, complexity and magnitude in a developing country. where the tenders were opened publicly, our proposal Canada has built two research reactors overseas, one was highly competitive. in lndia(2^) and one in Taiwan(2^). * Contract signed December 20, 1973 TABLE 4 Estimated costs for nuclear, coal and oil plants in Ontario in 1969 Canadian dollars (excluding escalation after 1969)

Nuclear Coal Oil

No. of units and capacity, MW(e) (net) 4x 500 4x500 4x500 Plant efficiency, % 29.1 37.9 37.3

CAPITAL-DIRECT COSTS, M$ Site, buildings and equipment (installed) 294 215 197 Nuclear fuel (Ms charge) 8 — - Heavy water 100 — - TOTAL DIRECTS, M$ 402 215 197

CAPITAL-INDIRECT COSTS, M$ Engineering 39 14 14 Construction overheads 43 22 22 Administration, inspection, etc. 15 8 8 Commissioning 11 1 1 Interest during construction 86 28 27 TOTAL IND1RECTS, M$ 194 73 72

CONTINGENCIES, M$ 8 4 15

TOTAL CAPITAL, M$ 604 292 284 Specific capital cost, $/kW(e) (net) 302 146 142

UNIT ENERGY COST, m$/kWh

Capital 3.63 1.77 1.72 Operations and maintenance 0.38 0.29 0.18 Heavy-water upkeep 0.13 - - Fuelling 0.71 3.11 3.12 TOTAL UNIT ENERGY COSTS, m$/kWh 4.85 5.17 5.02

Basic Assumptions for Calculation of Costs

Station net capacity factor 80% Life 30 years Interest rate 7.5% Fixed charge rate on capital 8.47'V, Heavy water capital cost $53.5/kg See notes for Table 4 on page 11. upkeep cost $40.0/kg upkeep rate (per reactor) 1.3 kg/h Nuclear fuel cost $46.0/kg U Nuclear fuel burn-up 223 MWh/kg U Coal cost (high sulfur) $ 9.12/ton $ 0.35/MBtu Oil cost (high sulfur) $ 2.15/barrel $ 0.34/MBtu

10 CANDU-PHW reactors are now established as sure that problems will arise. Some, common to all commercially available, commercially proven power nuclear power plants, are already known (Section 8) sources. All major technical questions affecting their but others will be unexpected. However there exists viability, e.g., low heavy-water losses, on-power fuel- within AECL, the utilities and associated industries a Mng, low fuelling costs and adequate burn-up from strong research and development effort in support of natural uranium, have been satisfactorily answered. CANDU reactors that has already demonstrated its At least as important, Canadian industry, engineering ability to identify and solve such problems before and management have proved themselves capable of they become crucial. bringing these complex projects to fruition. 5 Table 4 shows a 1971 estimate^ * of how the Obviously, Pickering's good performance has to be costs of nuclear power compares with alternatives, in maintained for the life-time of the station, and has to Ontario. In general, cost trends have been such as to be carried on into successive stations. Also, we can be increase the advantage of nuclear power and the learning process offers greater economies in a nev

NOTES PORTABLE A:

1. Nuclear plant based on 19o9 estimate for Pickering (in-service 19711.

2. Coal-Cited plant based on 1969 estimates for Lambton and Nanticoke lin-service 1970, 1972).

3. Oil-fired plant based on 19(i9 estimate for Lennox (in-service l:!7o).

4. A nine-month strike in mid-construction affected costs for Pickering, Lambton and Nanticoke but not Lennox.

5. Engineering includes development (nuclear only).

6. Nuclear fuelling costs include interest on out-reactor inventory (Ihree-month supply of finished fuel plus some in process and some uranium stock-piled).

7. No credit taken for sale of spent fuel.

8. Nu credit taken for value of D2 0 inventory at end of thirty years.

9. D;O initial capital investment is high because of unavailability of Canadian supply for Pickering.

10. The following table is a summary of more recent costs.

Costs of Nuclear Versus Fossil Fuel Stations (mills/kWh)

Nuclear Fossil High Low Sulphur Sulphur Fuel Fuel

Capital Costs 4.60 2.39 2.39 Operation & Maintenance 0.60 0.14 0.M Heavy Water Upkeep 0.20 - - Fueling 0.97 4.25 5.10 7.93 Total 6.37 7.08

a From an address by D.J. Gordon, Ontario Hydro, to the Fuels Planning Conference at Toronto, October 16, 1972.

11 technology than in a well-established one. There are several technical areas of development potential for STEAM TO TURBINE-^ CANDU-PHW reactors, notably: STEAM DRUM] — decreasing the capital costs by increasing the power from each fuel channel STEAM/WATER MIXTURE -- decreasing the capital costs by the development of a new process to produce heavy water more FUEL cheaply, (Section 9) and 3U*-, PRESSURE — decreasing the fuelling costs by the develop- ment of new fuels and fuel cycles'"6) anrj pressure tube alloys'^'). REACTOR However, in the next few years much greater savings are likely to result from: LIGHT WATER — decreasing the capital cost associated with interest during construction by shortening the COOLANT construction time decreasing the capital costs associated with engineering by spreading them over more plants HEAVY WATER WATER FROM of the same design. MODERATOR CONDENSER In short, we are only just beginning to exploit the benefits of CANDU-PHW reactors. BLW (Boiling Light Water)

5. ADVANCED CANDU REACTOR OPTIONS Figure 11 — Schematic diagram of a CANDU-Bl W reactor. A potentially valuable attribute of pressure-tube inevitable leaks in the turbine would make such a reactors, with coolant and moderator separated, is direct cycle prohibitively expensive. The elimination their ability to use different coolants with very little of the heat exchanger provides another direct saving change in the broad design or engineering of the in capital costs and also results in a small increase in reactor'^'. This versatility allows CANDU reactors thermal efficiency, which yields a further saving. The to exploit technological advances and adapt to reduction in operating costs resulting from the changing circumstances with only small design absence of loss of heavy-water coolant is a minor changes. Thus, advanced versions of the CANDU additional benefit. reactors will continue to benefit from experience gained with earlier versions. All CANDU reactors As might be expected, there are practical diffi- share a strong family resemblance, with different culties in realizing the advantages of a light-water coolants providing individual members of the family coolant. Light water captures many more neutrons with characteristic advantages. In practice, the two than heavy water so that if light water coolant were alternatives to the use of heavy water as a coolant for employed in a CANDU-PHW reactor without any CANDU reactors that are being considered are light other change, the reactor would not work with water and an organic liquid. natural uranium. Tho need for much more expensive enriched fuel would increase the fuelling costs, CANDU-BLW (Boiling Light-Water)*11-29-30) off-setting the gains. If the coolant is allowed to boil within the fuel channels, its mean density, and hence The principal advantage offered by the use of light neutron capture, can be reduced until at about 40% water as a coolant is a decrease in capital costs, due to the density of condensed water (a steam exit quality the reduction in the heavy-water inventory. Also, by of about 16% by weight) a reactor cooled by light allowing the coolant to boil within the reactor water and fuelled by natural uranium becomes channel, a direct cycle may be employed, with steam feasible. However, a boiling ligh(>water coolant from the primary coolant going directly to the requires a more complicated control system. With turbine (Figure 11). With heavy-water coolant, the heavy-water coolant, a positive power increment, in

12 decreasing the coolant density, decreases the neutron moderation and thereby tends to decrease the reactor STEAM TO TURBINE power again. This negative feedback makes for an inherently simple control system. Light water is more REACTOR STEAM significant as a neutron absorber than as a moderator, GENERATOR so that a decrease in coolant density causes a further increase in reactor power and a positive feedback FUEL which must be countered by a more sophisticated control system. The Gentilly reactor!"^), a prototype for the CANDU-BLW member of the family, is the world's only light-water-cooled power reactor which uses natural uranium. As with other prototype reactors, problems were exposed during commissioning, parti- cularly with the conventional components, e.g., the turbine, but full power was achieved in May 1972. The smooth operation of the reactor control system HEAVY WATER has satisfactorily answered the principal technical PUMP WATER FROM MODERATOR question on this option. A most significant achieve- CONDENSER ment of the Gentilly reactor was its construction OCR time, from commitment to criticality, of only 50 (Organic Cooled Reactor) months. This performance is as good as anything achieved or promised by other reactor types and augurs well for capital cost reductions in all future Figure 12 — Schematic diagram of a CANDU-OCR. CANDU reactors. activity fields around the circuit from activated An active development program for CANDU-BLW corrosion products are negligible. This factor could be reactors is concentrating on decreasing the capital important over the reactor's life by permitting simple, costs by increasing the power output from a reactor and hence inexpensive, maintenance. core of given volume. A conceptual study suggests that a reactor with the physical size of the Gentilly Although no prototype CANDU-OCR (Figure 12) one could produce three times the power. A capital is yet committed, the WR-1 test reactor has success- cost, for the whole plant, some 20% lower than for a fully demonstrated the principles involved'^3). Six comparable CANDU-PHW reactor seems feasible, but years of operation have shown that a coolant exit at the expense of some increase in fuelling costs, so temperature of 400°C is feasible, that coolant make- that the net decrease in the cost of the power up rates are adequately low, that methods for coolant produced would be about 10%. purification are satisfactory, that suitable structural materials are available and that activity fields around the primary circuit are trivial even when the reactor is CANDU-OCR (Organic-Cooled Reactor)(32) operating. A design study on a 500 MW(e) reactor is The organic liquid proposed as coolant is ar. oily currently assessing the incentives and additional mixture of terphenyls chosen primarily for its low development for the CANDU-OCR option. neutron capture and its high stability to heat and radiation. As for the CANDI.'-BLW option, elimi- Other coolant options are conceivable for CANDU nation of the heavy-water coolant decreases both the reactors, including liquid metals, molten salts and heavy-water inventory and losses, but coolant make- helium. It would be misleading to suggest that there is up costs are significant and a heat exchanger (steam any proposal to use these particular options. Rather, generator) is still required. The coolant properties are the possibility of their use illustrates the ability of such that the exit temperature can be 100 deg C CANDU reactors to exploit a technological break- higher than for water, while at a much lower pressure. through with the minimum of redesign. For instance, The consequent higher thermal efficiency and simpler development of a practical, high power, long life gas primary coolant circuit should give lower capital costs turbine could make a helium-cooled CANDU reactor than for water-cooled reactors. The corrosion of the very attractive. circuit materials by the organic liquid is so slight that A danger of such simplified accounts of the

13 advanced options, which concentrate on the prin- cycle is immune to changes and uncertainties in the ciples involved, is that immediate exploitation costs of enriching and reproces. <". services, and to a appears possible. In fact, a vast amount of unspecta- lack in demand for plutonium. cular development is necessary before a new type of Some compromise between these two cycles is power reactor can be committed commercially with possible with CANDU reactors. A very low enrich- confidence. A very thorough design study with ment (say 1.4% uranium-235 compared with the 0.77c supporting development is needed to justify com- in natural uranium) could be beneficial in reducing mitting even a prototype, while appreciable operating the capital costs, albeit with some increase in fuelling experience with the prototype should precede costs. This cycle would obviously require a source of commitment of a commercial station. In the fissile material but the value of the fissile material in meantime, existing CANDU-PHW reactors are benefit- the spent fuel would be sufficiently low that there ting both from their own development and from would be no economic necessity to reprocess. Both replicate production of a well-developed design. Thus these CANDU fuel cycles (natural uranium and very the CANDU-PHW reactors are far from obsolescent low enrichment) are sometimes referred to as "throw- and will continue to be constructed for manj> years, away" cycles. The term is descriptive in indicating with advanced options finding application where their that the economics of the cycle do not depend on particular strengths offer greatest reward. obtaining a credit for the spent fuel. However, it is misleading in any suggestion that the radio-active fuel 6. FUEL CYCLES AND FUEL UTILIZATION is irresponsibly abandoned- In fact, allowance is made for continuing storage, if required. The freedom to select the optimum coolant The natural uranium cycle is so simple that there is represents less than half the versatility of CANDU only one factor that could cause a serious increase in reactors. Even more important in the long term is the fuelling costs — an increase in the uranium supply their ability to use a wide variety of fuel cycles(2°). costs. Even so, CANDU reactors with the;* superior This feature, more than any other, ensures that the neutron economy, are much less sensitive to any rise CANDU family of reactors can remain viable and in uranium prices than the LWRs. This is because, in competitive for the foreseeable future. In any given CANDU reactors, the uranium utilization, expressed as the power produced per unit mass of uranium era an appropriate fuel cycle will be selected 36 depending on various factors including costs of mined, is about double that for LWRs( ). In the CANDU natural uranium cycle about 1% of the uranium supply, enrichment services, reprocessing uranium is burned; in LWRs the bumup is about 2% services and interest rates- of the enriched uranium in the reactor, but only Natural Uranium Cycle about Va% of the uranium mined. Present CANDU reactors use natural uranium and Canada's uranium reserves are large compared with the fuel preparation is particularly simple^34). After its own predicted needs and there is at least one irradiation the spent fuel can be stored indefinitely, school of thought claiming that the worldwide initially under water and then in dry, shielded uranium abundance is sufficient to provide low cost storage^). This simplest of all fuel cycles (Figure uranium through the year 2100(3^). Eventually, 13) is to be compared with the enriched uranium however, the price must rise as reserves are depleted cycle used by the light-water (moderated) reactors (Figure 14). A direct consequence of the use of enriched uranium is the need for a very expensive STORE J HWR 1 » PREPARATION ON SITE (about $1 billion) enrichment plant, or guaranteed 0.15% U 235 access to one. The enriched uranium cycle for LWRs also requires a reprocessing plant ($10 —$100

million), because the value of the fissile material REf INED NATURAL URANIUM remaining in the spent fuel is so high that recovery is 0-7% U 235 essential. Even after allowing a credit for the recovered uranium and plutonium, the net fuelling NATURAL URANIUM FUEL CYCLE costs for the LWRs are about double those for the CANDU natural uranium cycle. It is also apparent Figure 13 - Natural-uranium fuel cycle, as used in CANDU from Figures 13 and 14 that only the natural uraniuir reactors.

14 ' HUN t'i. SAI i

Figure 14 — Enriched-uranium fuel cycle, as used in light-water reactors.

ENRICHED URANIUM CYCLE

(DPI li)h- P.i SAL I

FUEL ' HWH 1 - T£M''^«V ^ THANSPOHfl I rXTRACT Figure 15 — Plutonium fuel cycle, as PREPARATION \ / STOHAl.E - j USEDFUlL I " I PLUTONIUM could be used in CANDU reactors.

HIGH ACt IVIIV REFINED NATURAL URANIUM WAS11 0 7*. U 22b 0 )0\ U 73b (WITH Pj HEi:VCLE1

PLUTONIUM RECOVERY FUEL CYCLE

and it will be necessary to adopt a fuel cycle that is recycle obviously requires a reprocessing plant, but more efficient in its use of uranium. Fortunately, at the type of plant needed merely to extract the least two such cycles are available to the CANDU plutonium can be simpler, and therefore less expen- reactors, providing them with excellent long-term sive, than one to recover both the uranium and 40 insurance. It is worth noting that the uranium plutonium, as for the enriched uranium cycle* ). utilization has a disproportionate effect on the Plutonium is both radio-active and very toxic so that amount of uranium available at an acceptable cost; a fuel fabricaticn costs are higher in the plutonium fewfold increase in burnup can increase by several recycle than in the natural uranium cycle. As a result orders of magnitude the uranium availability. This is of all these factors the fuelling costs for the pluto- because the higher burnup renders the fuelling costs nium recycle will probably not drop below those for less sensitive to the price of uranium, so that the the natural uranium cycle until there is either an much more plentiful lower grade ores become worth appreciable increase in the price of uranium or a 41 exploiting*3^. decrease in the cost of reprocessing* ). There is, however, another reason for interest in Plutonium Recycle the plutonium recycle. The addition of any fissile material, including plutonium, to the fuel gives the During irradiation some of the uranium-238 in the reactor designer an extra degree of freedom which he fuel is converted to the fissile plutonium-239. Part of can exploit to reduce capital costs, as discussed for this is burned in situ, contributing to the 1% burnup the CANDU-BLW reactors in Section 5. If some form of natural uranium, but the remainder, present in the of fuel enrichment proves advantageous for CANDU spent fuel, constitutes a potentially valuable asset. If reactors, the pluionium recycle (Figure 15) offers a it is extracted from the spent fuel and recycled into simpler alternative to the enriched uranium cycle new fuel (Figure 15) the uranium burnup can be (Figure 14). increased to approximately 2%*39). Plutonium

15 Thorium Cycle the inventory for an expanding system of fast reactors. Thus, in an expanding system, a massive At some even later stage, the 2% burnup of the plutonium inventory must be supplied from external plutonium recycle may be inadequate and a yet more sources. The inherent neutron economy of CANDU efficient fuel cycle be required. Plutonium recycle in reactors results in their being about twice as efficient a fast reactor is one such cycle, in which about 50% as LWRs in converting natural uranium to plutonium of the uranium can be burned. This is one of the two as a byproduct of their power production. Figure 16, main reasons given by its proponents for developing which summarizes the results of a study by the the fast reactor and is perfectly valid. Often over- European Nuclear Energy Agency, shows how the looked, however, is the fact that the thorium cycle combination of heavy-water and fast, reactors has a can do much the same in reactors of good neutron very low requirement for uranium. If CANDU economy, using the world's supply of reactors constitute a family, fast reactors, when they thorium(^B'42) Because CANDU reactors operating move in, may well come to be regarded as good on the thorium cycle would come very close to neighbours. producing more fissile material than they would consume, they have been designated "near-breeders". The thorium cycle is very similar to the plutonium recycle (Figure 15) with fertile thorium-232 instead 7. LONG-TERM OPTIONS of uranium-238 and fissile uranium-233 instead of plutonium-239. The lack of any naturally occurring In previous sections we have shown that tiucleur fissile thorium isotope means that the cycle must be power from thermal reactors is the only means at primed by fissile material from some external source, present available to fill the expected, growing gap e.g., an enrichment plant or a CANDU reactor fed by between energy demand and supply, that existing natural uranium. In either case the complete system CANDU-PHW reactors provide a competitive, com- imposes a demand on the available uranium supplies, mercial source of this nuclear power, and that the but at a level sufficiently low that known world CANDU family of reactors has the potential to reserves, including those in the oceans, are adequate remain competitive indefinitely. This situation could for centuriesH^). Even the oceans contain about be affected by future developments in other fields. 4.5xlO9 tcnnes of uranium, of which about a quarter Possible alternative power sources which may become (enough for several centuries) could probably be competitive include fast reactors, fusion reactors, recovered at a cost of only four times the present solar radiation, geothermal heat, wind power and price of uranium. Also, it is very important that the thermal gradients in the ocean. Nuclear power from thorium cycle leaves intact the uranium-238 that is fast reactors and fusion is the objective of major the feed for the fast reactor's plutonium recycle. development programs in other countries, with the Thus, in respect to maximum utilization of the feasibility of fusion as a useful power source still in world's resources, these two cycles should be doubt. regarded as complementary rather than competitive. AECL provides Canada with both a window In practical terms, the greatest difference between through which to view the rest of the world and a the two cycles is that the thorium cycle can be frame of reference. The means employed to keep realized by evolutionary development in reactors abreast of potentially significant scientific discoveries virtually indistinguishable from present CANDU reac- and new technologies include: tors, while the fast reactor cycle demands the innovation of a complete new system that, in the — AECL's own fundamental programs USA alone, is expected to cost roughly $6 billion — collaboration and exchanges within the over the next twelve years^'. Canadian scientific community The CANDU natural uranium fuel cycle best — participation in national and international complement's the fast reactor's fuel cycle during the meetings, and latter's introductory period(36,4o)_ un(jer equili- — bilateral agreements with the atomic energy brium conditions, the fast reactor produces more authorities of other countries. fissile material than it consumes — hence the term "fast breeder". However, a fast breeder requires a Periodically, AECL conducts deliberate and thorough large initial inventory of plutonium and the rate of reviews to determine how external developments breeding is not expected to be sufficient to supply all affect the Canadian program.

16 Integrated uranium re- quirements to 2010

10 metric tons

200

180

Isotopic 160 separation plant 140 capacities in 2010 12° 100

10 metric 80 tons/year 60

40

20

(Nuclear News Mar. 7 1) Figure 16 - Uranium requirements and separation plant capacities estimated for Western Europe bv the year 2100 depending on various reactor strategies. Each block indicates high and low estimates. FB •= fast breeder; LFR = liquid-fuel reactor; FC = fast converter. (Illustrative Power Reactor Programmes, ENEA, 36p, 19681

17 EAVY WATER Fast Reactors REACTOR - PICKERING Countries at present using LWRs believe that these are only interim solutions and that, before the end of LIGHT WATER this century, their inefficient utilization of uranium REACTOR will exhaust low-cost uranium supplies, thus ren- f UNITED dering their fuelling costs excessive. Most countries, STATES in looking for a more efficient type of reactor for FAST I REACTORS J their long-term programs, have gone to the other UNITED extreme and are developing fast breeder reactors. I KINGDOM However, any country wishing to become an inter- i 0.5 1.0 1.5 nationally competitive supplier of fast reactors would MILLS/KWH have to undertake a tremendously expensive develop- Figure 18 — Projected fuelling costs in the period 1085 to ment program. Even taking advantage of the 2000 for three reactor types. The arrows indicate the clirec experience already available, the cost has been tion in which the costs will change with time; far Pickering estimated at about $2 billion over a period of nearly type reactors the net effect is small and Ihe direction twenty years before any returns begin to be uncertain. received^). Despite the formidable technical the point of view of making predictions, the net problems facing fast reactor designers, there is little fuelling costs are obtained as a small difference doubt that they will prove successful in providing between two large numbers, the sum of fuel fabri- utilities with a fast reactor option by the end of the cation and reprocessing costs, plus interest charges on 1980s. What is uncertain is the extent to which a very expensive inventory of fissile material both in- solutions to the problems will affect the economics. and out-reactor, less a credit for the new fissile Fast reactors, with their liquid metal coolant and material produced. The inventory charges depend on two-stage heat exchanger, are more complex than interest rates prevailing some 30 years from to-day water-cooled reactors but their higher thermal effi- while the amount of new plutonium produced ciency tends to compensate. As a result U.S. depends critically on the detailed reactor physics of a estimates^") indicate that capital costs for fast reactor that has not yet been designed. With these reactors will be about 10% higher than those for and other uncertainties it is not surprising that there thermal reactors (Figure 17). Operating and mainte- is a wide spread in estimates of the fuelling costA ' nance costs should be roughly the same for both (Figure 18). Most estimates are lower than those for types. It is in fuelling costs that the proponents of LWRs but the range of estimates overlaps those for a fast reactors claim an advantage. Unfortunately, from CANDU-PHW in the same period. When all com- ponents of the power cost are summed, it is impossible to predict at this time whether fast THERMAL reactors or CANDU reactors will eventually provide 1.0 I- vREACTORS the lower cost. If the power cost of the fast reactor turns out to 0.9 - FAST be disappointingly high, CANDU reactors will have an REACTORS obvious advantage. If fast reactors are over- RELATIVE 0.8 whelmingly successful, with very low power cost, CAPITAL their resulting rapid growth rate will force up the COST 0.7 FOSSIL price of plutonium, which CANDU reactors are best . STATIONS able to produce. The effect will be to narrow any cost 0.6 differential between the two types. If costs from the 0.5 two are roughly the same, CANDU reactors are likely to appeal to less highly industrialized countries 0.4 because: 1970 1990 2010 — simpler technology is employed, DATE ON LINE — there will be greater operating experience, and

Figure 17 - Projected capital costs for fast reactors, thermal — less capital is required to initiate a power reactors and fossil-fired generating stations. system.

18 Thus both the resources argument and ft? economic capital cost will be particularly low with the sort of argument suggest that both CANDU and fast reactors equipment envisaged. It is also clear thai the contain- can profitably co-exist in the same world. Having also ment of tritium and of materials rendered radio-active considered the cost of developing fast reactors, and by neutron capture, will add further difficulties and the fact that such expenditures would slow down the costs. development of CANDU reactors, AECL does not The containment of the plasma has proved to be propose any Canadian development of fast reactors. an exceptionally difficult technical problem on which progress over the last 20 years has been slow, in spite of major national programs. Recently a technique called inertial confinement (successfully used in the 9 50 Controlled thermonuclear fusion (Figure 19) is H-bomb) has received increasing attention^ - *. receiving much attention throughout the world This requires the rapid deposition of energy and (about $120M was expended in 1971). There is as yet reaction ignition before the fuel can disperse. Pursuit no guarantee of ultimate success, although neutrons of this method became possible through the have been produced from hot plasmas. The current appearance of high-power pulsed lasers, such as the aim is to produce and contain a hot plasma for a Canadian-invented CO2 TEA laser, and the develop- sufficiently long time that the thermonuclear energy ment of accelerators producing intense relativists release equals the kinetic energy stored in the plasma. electron beams. AECL scientists have maintained a There is optimism in the fusion community that a watching brief on the development of fusion solution to this problem will be obtained by 1980; technology, which has many areas of contact with such a demonstration would be equivalent to the first accelerator technology. achievement of a critical fission chain reaction in The main thrust in fusion research has been 1942. Many formidable technical problejns would towards a power reactor, but a fusion device can also remain before a demonstration fusion power reactor be regarded as a neutron source (Figure 19) and this could be built, including methods of fuelling, removal objective might be more easily attained. For example, of spent fuel, provision of adequate structural it is conceivable that the first economic application of materials, cooling and tritium regeneration. In the fusion could be as a neutron source to provide fissile absence of a feasible design, any economic evaluation material for a CANDU system. In such a fusion- is ruled out, but it is difficult to believe that the fission symbiosis, the fusion-reaction part could be relatively small and would not in itself have to "1 achieve a net energy gain.

51 52 + (OO)~— (rt) + O I 32SMEV Electrical Production of Neutrons^ ' )

DtuTEHl'jM HELIUM 3 NEUTRON Another possible neutron source for use in the production of fissile material is spallation, in which TRITIUM HELIUM a NfcUl HON the bombardment of heavy elements by high energy protons releases many neutrons(Figure 20). In one conceptual des:^n, using an accelerator to bombard Figure 19 - Simplified diagrams of two possible fusion reactions. (Scientific American, 225(3), p. 67, September uranium, the energy released in the process is 19711 harnessed to drive the accelerator and the neutrons

Figure 20 — Simplified diagram of a possible spallation reaction. A total of 20-25 neutrons, each with a mean energy of about 3.5 MeV, results from the cascade.

19 are captured by fertile material to produce fissile radio-activity normally retained safely within double material for the CANDU thorium cycle. The spalla- containment and behind heavy shielding in the tion process is economically unattractive with reactor building, and that this would harm the existing technology and the current low price of surrounding population. By recognizing the possi- fissile material. Realization of this concept depends bility of a severe accident, by analyzing the chain of both on the evolution of a satisfactory accelerator events that could produce one and by suitable design and considerable engineering development One and regulation of the reactor system, the probability version of a novel acceleration technique, the electron of the occurrence can be made extremely low. NO I hat ring accelerator, offers the hope of very much higher the risk involved is probably much less than that from accelerating gradients and correspondingly shorter natural disasters. and cheaper accelerator structures. The electrical In essence, the Canadian reactors consist of two production of neutrons provides a suitable long-term parts — process systems, which include the reactor objective for AECL's accelerator development pro- 5 itself, the primary coolant circuit. Hie reactor power gram* ^) which is directed towards medical and regulating system and the electrical generating industrial applications in the shorter term. system; anil the prutcctive systems, which include the automatic systems to shut down the reac'jr and the Energy Storage and Transmission various forms of containment'00'. The indh idual systems are designed for high reliability and arc* The very low fuelling costs for CANDU reactors regularly touted in service lu ensure thai Ilicir encourages their continuous operation to supply the reliability is maintained. Complete independence is base load. In time, as nuclear power provides a greater demanded between the two parts. These measures fraction of the total generating capacity, the nuclear ensure that u severe accident could only arise from a stations will be required to load-follow. There will most unlikely combination of two independent then be an incentive to store energy during off-peak events that are themselves very unlikely. Even so, the periods for release during peak periods. Since the plant is also designed so that any release of radio- electrical energy might be converted to chemical activity to the environment, assuming that a fault in a energy for storage, e.g., hydrogen generation, the process system coincides with failure of any one question of the relative costs of energy transmission protective system, is kept within acceptable limits. by different means is relevant. Also the cost of energy transmission will continue to affect the optimum size No new development in any branch of nuclear of power stations and hence their costs. Although power can be introduced until it satisfies the:* very these subjects are of potential interest to the strict safety requirements, however great the Canadian nuclear power program practically no work economic incentive for its adoption. In Canada, as on them is being undertaken within the program, the elsewhere, the nuclear industry is not the arbiter on only exception being AECL's management of the matters relating to safpty and public welfare. An ultra-high voltage Nelson River Transmission Faci- independent agency, the Atomic Energy Control lities in Manitoba*54). Board (AECB),(5ti) is charged with this regulatory- function and must be satisfied that a nuclear plant is 8. COMMON PROBLEMS safe before issuing construction or operating licences.

Certain problems, common to all nuclear power Controlled Releases of Radio-activity enterprises (including fusion), are receiving serious attention throughout the world: All nuclear power plants release some radio-activity to the environment, but the amounts are very Prevention of Severe Accidents small.The level of these releases, both to the atmos- phere and to cooling waters, is continuously With any mechanism, malfunction of a com- monitored and regulated under AECB supervision so ponent, or human error, can lead to an accident. that any doses to the population are within limits Where power of the order of several hundred recommends by the International Commission on megawatts is being released as heat, there exists the Radiological Protection*5^-58). In practice, the possibility of a very rapid rise in temperature. With actual releases are sufficieiitly small that the resulting nuclear power, the major concern is that the accident exposure to any member of the public, even those may cause the release of a large fraction of the living at the boundary of a nuclear power plant, is

20 only a few percent of Ihe inevitable exposure to strictly limited, he can work only for short periods in naturally occurring radiation, e.g., cosmic rays. a high field. Thus, in high field areas, more mainte- While there is no conclusive evidence that low level nance workers would be required than would exposures are harmful, it cannot yet be proved that otherwise be necessary, with a consequent increase in any small increase in the natural background of the radiation burden of the population as well as in radia'.ion is completely harmless. Several studies of the cost of maintenance. the long-term effects of high natural background The remedial measures being investigated in radiation on people are in progress, such as one^^) jn Canada and elsewhere fall into threp categories: a region of Southern India where the soil is very rich ~ selection of circuit materials and coolant iti ihorium and the exposure of some people is as high chemistry to minimize the radio-activity from as 20 times the average. In only the group of corrosion products, individuals with the highest exposure was there any suggestion of an adverse effect, and this was at a level — development of methods for the removal of the that was not statistically significant. It is important to corrosion products from the circuit, and note that this kind of study is being continued, so as — changes in the circuit lay-out and provisloi- of to provide information on the possible risks to large shielding to minimize radiation fields at populations exposed to low levels of radiation. locations where maintenance is needed. One method of removing corrosion products was Management of Radio-active Wastes tested under service conditions in the Douglas Point Operation of any nuclear reactor also results in the prototype reactor. Figure 21 shows how the fields were successfully reduced by a factor of about production of radio-active waste products that must (60) not be released to the environment. With fission six reactors, the principal contribution to the wastes is from the fission products present in spent fuel. Thermal Discharges(61) Contrary to some widely held beliefs, fusion reactors too would generate radio-active wastes, so that their Since almost all energy ends up as heat, the adoption would not remove the problem. There are problem of thermal pollution on a global scale relates differences of opinion throughout the world on the to the world's demand for energy and is unaffected safest means for the control of radio-active wastes by the alternative means for satisfying the demand. and, again, considerable effort is being devoted to the The limiting forecast demand (Figure 1) amounts to study of this topic. only 0.5% of the sun's energy received by the earth, and is therefore unlikely to have a large effect. Within the Canadian program, the policy that has On a smaller scale, the waste heat from a power been adopted is to provide monitored and supervised station heats up whatever cooling water is used, river, storage of the wastes for as long as they constitute lake or sea, but the effect is localized; for the any potential hazard, under conditions that permit Pickering station a temperature rise of the order of 1 retrieval at any time. This procedure provides the deg C is expected at a distance of one mile from the greatest assurance against any eventuality that might plant. Close to any plant the increase in water cause a release of the radio-active wastes. A closely temperature will increase the rate of growth of related problem concerns the transportation of radio- practically all species of aquatic life. Where the water active materials. Here, too, present regulations ensure is already warm, this effect could be undesirable and adequate safety while research continues. cooling towers or cooling ponds have to be used to remove the waste heat. In Canada, however, where Maintenance of Nuclear Reactors most of the large bodies of water are cool or cold most of the year, these small temperature increases Corrosion products in the primary coolant circuit would be more likely to be considered to be of a reactor may be carried into the reactor core advantageous than detrimental A study of ways to where they become activated. If they are then carried utilize waste heat in the Canadian climate is in the out again and are deposited on the out-of-core planning stage. surfaces, e.g., L the heat exchanger, they can cause high radiation fields around the circuit. Since the While recognizing these common problems that are permitted exposure to any maintenance worker is shared with other nuclear power programs, it is worth

21 — AUGUST 19/1 DECAY DUPING SHUTDOWN "OCTOBER H371

Figure 21 — Hisiory of the radioactivity fields in the boiler mom of the Douglas Point reactor, shewing the major reduction due to the removal of corrosion products.

EFFECTIVE FULL POWER DAYS noting certain advantages enjoyed by the Canadian principle, be reduced to economic terms. For program. Our cool climate, our copious water instance, if the growth of nuclear power led to a resources and our low density of population combine significant increase in the radio-activity in the atnio^ to minimize the effects of thermal pollution. Our phe-°, lower releases could be achieved at the cosl of natural uranium fuel cycle, which avoids the necessity installing additional equipment. Current studies are of reprocessing spent fuel, involves very little hand- aimed at answering the question at what level the ling and transportation of radio-active wastes. The costs outweigh the benefits to the community. The fission products are bound in corrosion-resistant nuclear power industry has a highly creditable record uranium oxide which, in turn, is in corrosion-resistant for social responsibility, in that it was the first in the zirconium-alloy containers. The CANDU-OCR is world to introduce human safety as a major unique in its nearly complete freedom from radiation component of its development program and Lo fields around the primary coolant circuit. Finally, integrate pollution control in the ^ pressure tube reactors offer advantages in three distinct areas relating to the integrity of the primary containment of the fuel and coolant(62); 9. SPECIFIC CANADIAN CONSIDERATIONS — the design simplicity and thin walls of the pressure tubes (compared with pressure vessels) Heavy-Water Supply provide much greater confidence in any stress analysis and allow very thorough quality Obviously heavy-water reactors require a supply of control in fabrication, heavy water. Since the operating losses amount to less than 2% of the inventory per year, in an expanding — actual full-size pressure tubes can be irradiated system most of the demand is to supply the inventory under power-reactor conditions in test reactors, for new reactors. Figure 22 shows the expected and subsequently tested to destruction to domestic demand for heavy water to 1985. At establish safety limits. Even in service, the tubes present Canada has one 400 ton/year heavy-water can be monitored to confirm their predicted plant operating at about 60% of its design capacity at performance, and Port Hawkesbury, Nova Scotia, an 800 ton/year plant — should a flaw develop in a pressure tube, its under construction at Bruce, Ontario, of which the presence can be detected by the associated first 400 ton/year unit is now being commissioned, and the 400 ton/year Glace Bay Plant in Nova Scotia, leakage of coolant before it reaches the stage of 4 rapid propagation. which is being rehabilitated^ ). These are expected to reach maturity in 1975, 1977 and 1979 respec- The problems discussed in this section are often tively and their predicted output is included in Figure the subject of sociological debate but all can, in 22.

22 20000r hydrogen sulphide gas (che "G.S." process) which is illustrated schematically in Figure 23a. The G.S. process was first introduced on a plant scale early in the 1950s, in the USA, and very little research and 16OOoi- development has been devoted to it since then. Thus I the Canadian program includes a search for improve- ments in the existing process as well as for more economical processes(65<66). Development work is 1476Mg/YEAR : proceeding, originally within AECL's own research program but now increasingly by industrial develop- METRIC TONS (CUMUIAIIVEI ment contracts, on two promising alternatives shown FORECAST PRODUCTI (p H. + B.H W.P. * G schematically in Figures 23b and c. The low deu- terium concentration of natural water, and the large flows which must, consequently, be handled, cause all these processes to be capital-intensive. Very roughly,

PH PORT HAWK tSBURY I the cost of the equipment increases with its size and aOOOJ- B H W P - BRUCt HEAVY WATER PIANT complexity. Thus the comparison made in Figure 23 G,B - GLACE BAY j suggests that the hydrogen-water process (Figure 23c) is potentially the most economic, and this is confirmed by more detailed estimates. However, 19/4 76 78 BO 82 84 certain aspects of the technical feasibility have still to YEAR be demonstrated and a great deal of development is required, so that it will be close to ten years before a Figure 22 - Projected supply and demand of heavy water in

Canada. commercial unit can be operating. In light-water reactors the fuel is enriched but the The present shortage of heavy water can be largely water is used in its natural condition. In heavy-water attributed to the failure of the Glace Bay Plant to reactors, natural uranium can be used as fuel, but the come into production in 1966, as originally expected. water must be enriched, at least for the moderator. This failure, in turn, can be attributed, in broad Since fuel is consumable but the heavy water is a terms, to trying to do two things without adequate capital item, the investment in heavy-water plants technical support — scaling up a process and impor- would be very much less than that in current enrich- ting a technology. Part of the present incapacity of ment plants, for a zero-growth power system. For an the Port Hawkesbury Plant is due to limitations expanding system, however, the two investment sums imposed by foaming of the water in the exchange can be comparable, with the value of the growth rate towers. This is the sort of technical problem that determining which is the greater. Even in an must be expected in starting up any large new plant expanding system there is one important difference. and that is susceptible to solution by competent To yield an economic product, enrichment plants research, development and engineering. The lessons must now be built in very large units, costing about learned at these two plants are being applied at Bruce, $1 billion, whereas heavy-water plants are economic but there is no guarantee that the Bruce plant will not in much smaller units, about $100 million. The use of produce its own problems due, for instance, to smaller plants allows the product supply to match the specific trace impurities in its water supply. Thus, demand much more closely and the time-scale to continued strong technical support of all these plants commit a heavy-water plant is similar to that for a is essential. Figure 22 also indicates that early power reactor. However if centrifuge enrichment commitment of another heavy-water plant is neces- plants become economic, they could also be built in sary if we are to avoid a further shortage in the units of roughly $100 million. 1980s. Since the heavy-water inventory contributes about Industrial Development and Growth 15% to the capital costs of CANDU-PHW reactors, any means of reducing its cost are of interest. So far, The Canadian nuclear program consists of three all Canadian heavy-water plants are based on an major sectors, a federal agency, provincial utilities isotopic exchange between the water feed and and industry. In a typical project, AECL acts as the

23 (a) G.S. PROCESS (c) H,-H2O PROCESS

t.-- IHYOROGEN SULPHIDE I I WATEH

(b) STEAM-H2-AMINE PROCESS Figure 23 -Schematic diagrams ot existing (a) and two altarnative (b & c) processes for producing heavy water. Equipment sizes are to relative scale and pipe widths are propor- tional to flow.

I I HYDROGEN m AMINE 1 [ WATER nuclear consultant, having previously performed the From the beginning, AECL recognized the need to necessary development; the utility designs the con- assist in the development of new industries intimately ventional part of the station and is responsible for associated with the reactor proper, but only later and construction and operation; industry supplies the of necessity have we concerned ourselves with the equipment, components, instrumentation, fuel, etc. supply of conventional equipment. The basic reason and provides services and consultancy on contract. for this concern is that the economics of our nuclear Originally, the reactor design was done in industry power system cannot tolerate the degree of unrelia- but there were insufficient projects to keep several bility normally accepted* in many components. design teams occupied continuously and valuable However, it is our impression r»m all industry would experience was being lost at the completion of each benefit from the sort of improvements we are project. Concentration of the nuclear design function demanding. in AECL's Power Projects group has provided a continuity from one design to the next. The nuclear fuel industry in Canada started in 1957, when two companies attached members of The high Canadian content of the nuclearsteam their staff to the Chalk River Nuclear Laboratories to supply system is encouraging but tends to conceal participate in the fuel development program. After a difficulties, only some of which have been overcome. few years, these individuals returned to their home

24 bases and founded technology teams in the fuel To-day the total Canadian nuclear fuel salt's are about companies. Meanwhile, we have bought our experi- $15 miilion per annum and Figure 24 shows how mental fuel from these companies and supported they are expected to climb rapidly!11). However, out- research and development work in their laboratories. of the difficulties becomes apparent when it is We now have two fuel fabricators capable of realized that it will be roughly 1980 before thc- supplying high quality fuel at the world's lowest price industry can fully support a research anJ develop- in open commercial competition, and a third ment effort of ten professional staff members company is planning to enter the market in 1975. together with the associated technical support, assuming that 1% of sales can be devoted to this 200 purpose. Predicted expenditures in other areas are shown in 4000 - 10 M$ Figure 25( ). Nuclear power provides only a small TONNES U fraction of any supplier's market for the more con- OR JOBS ventional components. Furthermore, the principle of - 100 2000 open, competitive bidding can result in a given type of component being supplied by different companies for successive stations. Thus the expertise developed in one company may not be utilised at the time of the next order. In addition, where the supplier is a 1970 1990 subsidiary of a foreign corporation, without a research and development effort in Canada, it is Figure 24 — Projected Canadian annual production of nuclear difficult to use the technique of an industrial develop- fuel. The production of finished, CANDU natural-uranium ment contract to help improve the product^'). fuel containing 1 tonne of uranium takes appro).!, lately 1 Much of the remaining foreign content of MM* man-year, from mine to reactor.

1600 -

I 400 Figure 25 — Projected cumulative expenditures in EXPENDITURES, the Canadian nuclear industry, other than fuel. $ million i 200

25 CANDU reactors is in the seamless tubing used in The development of fast reactors is receiving three applications — fuel assemblies, pressure tubes massive government subsidy throughout the world and tubes for heat exchangers. As elsewhere, the and they can be expected to be serious contenders in present nuclear demand would utilise only a fraction the 1990s. However, we have already pointed out of the output of a plant large enough to be economic (Section 7) that they are most likely to complement and intsgration with some other product line is CANDU reactors. High-temperature, gas-cooled reac- necessary to support a viable industry. tors (HTRs), although not yet tested on the In the fiscal year 1971/72, AECL's expenditures commercial market, have the potential to be compe- on manufacturing development contracts amounted titive and must be watched closely. If these become to about $5.5 million, spread among 33 companies. accepted commercially, it will probably first occur Of the total, 45% was on fuel, 28% on mechanical where cooling water is scarce, since the high thermal engineering and 20% on materials, while the efficiency of this reactor type gives it an advantage remainder covered such diverse fields as heat transfer, under these circumstances. HTRs, like fast reactors, fluid flow, chemical process d velopment, instru- may complement CANDU reactors, since the fissile mentation and engineering design. This distribution uranium-233 produced from the thorium fuel cycle in has already changed drastically with AECL's rapid CANDU reactors is a valuable fuel for HTRs. increase in support of production processes for heavy water, now that it is charged with a major responsi- Nuclear Power's Role in the National Economy bility for heavy-water supply. There is little doubt that secure energy supplies are vital to any nation. Adequate power is essential to Foreign Competition industrial development, in both primary and secon- dary industries, while abundant cheap power provides At present out most serious competition is from industry with a valuable advantage. Figure 26 shows the US designs of light-water reactors. It is com- the very strong correlation that evists between the forting to know that CANDU reactors have been gross national product (GNP) of a cf antry and energy brought to commercial realization with far less consumed. Until an increase in GNP is replaced by 68 government financial support than the LWRs( ), but some other criterion as a national goal -e can expect this does nothing to negate their two big advantages: the demand for power to keep increasing for this — the large numbei of reactor-years of LWR. reason alone. Increasing emphasis on the quality of operating experience helps to provide confi- life is more likely to increase than diminish the dence in the design. The Pickering station's demand since pollution control, effluent purification, outstanding record has helped to even the score waste recycling and similar projects are heavy con- somewhat, but measured in reactor-years we are sumers of power. At present, electrical power going to remain at a disadvantage for many production in Canada is expanding at a rate of 6% to years. 7% per annum, while nuclear power is expected to expand at an average of 15% per annum over the next — their much greater production rate ?ives them twenty years. greater benefit from standardisation and the learning process and allows them to spread There can be few Canadian industries, particularly overheads over more units. While there is no in areas of sophisticated technology, that offer such inherent reason for any appreciable differential assurances of high and continuing growth. The fact in capital costs between LWRs and CANDU that the Canadian product is fully competitive reactors, this factor gives the LWRs an advan- provides a tremendous opportunity — but no tage that must be offset against our lower guarantee of success. The structure of the nuclear fuelling costs. power industry provides useful protection against foreign takeover, without fear of contravening tariff Canada could, perhaps, learn from the USA in agreements. It also provides a means of helping to letting foreign aid and domestic industrial develop- improve the technology of components suppliers ment reinforce each other to their mutual benefit. whose business extends beyond the nuclear power We believe that the CANDU reactors provide the best industry. Finally it assists in the rationalization and nuclear system for a developing country for the same standardization of nuclear power across Canada by a reasons that they are good for Canada and a larger series of agreements between the federal agency and market would help to reduce their cost. the provincial utilities.

26 175 U.S. < < o CC HI 150 J a.

CD u. O CANADA • V) 125 O

U.K.*

z 100 g BELGIUM AND LUXEMBOURG* a. S • AUSTRALIA oo •GERMANY Z o 'SWEDEN o 75 -• POLAND > U.S.S.R.* • DENMARK cc . •NORWAY UJ z NETHERLANDS UJ •HUNGARY SOUTH AFRICA' •FRANCE s „ IRELAND* .NEW ZEALAND

i FINLAND BULGARIA* ROMANIA • 8 JAPAN ARGENTINA* • ITALY 25 MEXICO "SPAIN • • • CHILE YUGOSLAVIA COLOMBIA* • GREECE BRAZ*L»PORTUGAL •INDIA «GHANA [ 500 1,000 1,500 2,000 2,500 3,000

GROSS NATIONAL PRODUCT (DOLLARS PER CAPITA)

Figure 26 — Correlation between energy consumption and gross national product 'or various countries. (Scientific American, 225(3), p. 142, September 1971)

27 10. SUMMARY OF CANDU POWER REACTOR superior neutron economy, an advantage that tan be CHARACTERISTICS exploited to use natural uranium as fuel or to provide near-breeding of fissile material. The following are some of the advantages that are inherent in the CANDU power reactor system. Simpie Fuel The fuel for CANDU-PHW reactors is extremely Neutron Economy simple (Figure 27), requiring only two materials and six different components to manufacture all the fuel Neutrons are the currency of nuclear power and bundles for a reactor(34). This simplicity, together every neutron wasted imposes a direct economic with the use of natural uranium, gives us the world's penalty on the system. A simple illustrative calcu- lowest fuelling costs, as proved by actual commercial lation sets a price of about $1 million/kg on experience (Table 5). The same simple design is neutronsi^'. Reactors with a heavy-water moderator adaptable to the future CANDU reactor options will always enjoy the fundamental advantage of already discussed.

1. ZIRCALOY STRUCTURAt END PLATE 2. ZIRCALOY END CAP 3. ZIRCALOY BEARING PADS 4. URANIUM DIOXIDE PELLETS 5. ZIRCALOY FUEL SHEATH 6. ZIRCALOY SPACERS

Figure 27 - Fuel bundle for the Pickering reactors (diameter 10 cm, length 50 cm).

TABLE 5 Comparison of fuel fabrication experience for Canadian and US reactors (up to beginning of 1971)

CANDU BWR" PWR*

Bundles 31,800 7,800 3,300 Elements 700,000 380,000 670,000 Weight 540 1,530 1,400 (tpnnes U)

BWR — boiling-water reactor; PWR — pressurized-water reactor

28 Pressure Tubes versus reprocessing plants; heavy-water plants intro- duced in relatively small units versus a single large The advantages of pressure tubes for reactor safety enrichment plant. Departures from this basic were mentioned earlier (Section 8). In addition, the simplicity will be adopted only if and when they are use of pressure tubes facilitates development and economically justified, allowing the capital invest- permits it to proceed in an evolutionary manner(62). ment to be spread over a much longer period. The Experience with the tubes of one reactor can lead to ability to introduce a nuclear power system with improvements in the tubes for subsequent reactors of minimum investment must be a very important the same type. More important, much of the advantage to any country that does not already experience gained with one type is relevant to more possess a nuclear infrastructure for weapons advanced types, e.g., from CANDU-PHW to CANDU- production. BLW. Even the points of difference can be fully tested in test reactors, something possible only for Since the same sentiments are always more con- pressure tube reactors. vincing when expressed by an impartial observer we cite some remarks extracted from an address given in 1971 by a French pioneer of atomic energy, Lew On-power Fuelling ^7^ The use of pressure tubes facilitates on-power Concerning the position on US reactors taken fuelling. In CANDU reactors, on-power fuelling was in 1969 by practically all advanced countries. originally introduced because it improves the neutron "They are all now building their American-type economy, but it is also very valuable in allowing rapid reactors without quite knowing where they are discharge of any failed fuel. Not only dees this going to get their fuel... All Europeans have vague freedom reduce the release of radio-active fission ideas of building some isotope separation plants; products (thereby possibly avoiding mandatory should not the economists tell them how much it power reduction of the reactor), but it also means will add to the cost of energy from the American fewer constraints on the fuel design. type? In addition, this technique is a very wasteful way of using U-235." Adaptability His advice to Europeans was "Follow the Canadians rather than the British; you can rely on The adaptability of CANDU reactors to different natural uranium, no problem with the fuel supply, coolants (Section 5) and different fuel cycles (Section much better utilization of natural resources." 6), without any convulsive changes in basic design or technology, provides them with the potential to "Except for thermal effects, the Canadian way remain competitive for the foreseeable future. To still seems to be safest for the environ- appreciate this advantage one has only to examine the ment. . . . The Canadian effort is extremely impor- situation in other countries, where a totally new tant for the future of nuclear energy and should be fast-reactor technology is having to be developed to continued, but preferably not in Canada replace the LWRs. The adaptability of CANDU alone. . . . The simplest type is still your Canadian reactors allows them to make efficient use of natural reactor, providing you can get your heavy-water vesources, so that they may either complement or production problem solved. The fast breeder will take the place of fast reactors, depending on the always be more complicated and the thermo- performance of the latter. nuclear (fusion) reactor will be more complicated still." System Simplicity Other foreign authorities have expressed similar confidence in the CANDU system'71'72-73'74'. As well as having simple fuel and simple pressure tubes for coolant containment, present CANDU 11. RELATED CONSIDERATIONS reactors operate on the simplest possible fuel cycle. Consequently, the capital investment for a CANDU Competition power reactor system is less at each stage: fuel fabrication plants for natural uranium versus plants One of the comparative industrial advantages for enriched uranium; a metallurgical industry for which Canada has enjoyed in the past has been cheap small, thin-walled, seamless tubes versus one for large, electric power. In the long term, electric power will thick-walled, welded vessels; spent fuel storage vaults provide an increasing fraction of the world's energy

29 and nuclear generation, an ever increasing portion of development in this field. Developments initiated by electricity supply. Even to maintain its position, AECL are now having a secondary effect on con- Canada must have cheap nuclear power and also ventional equipment of the type used in all large manufacture nuclear equipment. Thus, nuclear power thermal-electric generating stations, as nuclear development in Canada is in the unusual position that requirements are somewhat different and more strin- cost-benefit studies on development costs versus gent than those for fossil-fired thermal units. Whether direct benefits in lower energy costs should be subject AECL should carry the development of better to the overriding consideration that our nuclear components, such as valves, seals and heat exchangers systems must be kept fully competitive with those of further into non-nuclear areas is still a question. other countries. In other countries strategic consi- Similarly the Canadian long-term strategy relating :-j derations seem to weigh even more heavily than this steam turbines should consider whether they should concept. All major countries maintain a significant be bought off-shore, manufactured under license, or level of nuclear research and development, apparently manufactured under license with supporting develop- regardless of whether or not a new reactor type is ment. Thus ii may be desirable to study fossil-fired being supported. thermal-electric generation, so as to ensure that the cheapest possible energy is available from a source Over the years AECL has evolved a number of that is now becoming of major importance in Canariu. management-investment techniques in advanced fields of technology which may have application elsewhere In the implementation of development results, (hi- to obtain the best result from Canadian industries and "buy Canadian" problem has to be faced. Experience resources. For example, the Taiwan research reactor has shown that, while AECL can, at reasonable cv.i, project, with a value of about $35 million, was support the development of a high quality com- negotiated by AECL, and AECL acts as general ponent, Canadian industry's bid on initial production contractor and provides project and operations for commercial purposes generally cannot compete- management. However, all the actual design and against the large, established suppliers in other construction is being done by others. countries. To properly establish a Canadian supplier. AECL has an interdisciplinary', strongly mission- ;i direct government subsidy may be required on I he orii'iiled and balanced, staff and facilities spanning initial production, and subsequently on a scale thu' activities which range from fundamental research to decreases with time. A good example of this is AECI. the commercial implementation of nuclear power experience with the iniliatior of CAKDl' pressure projects. These, plus the ability to act as a focus for lube manufacture in Canada. Canadian industrial effort, provide our main competi- tive strength. However, it should be realized that each Investment Decisions of our competitors has a very large organization, which has at its disposal extensive resources, espe- Every nuclear reactor type which is commercialh cially in the field of heavy engineering development, viable requires a product from an isotope separation design, manufacture and construction. They are also plant, either heavy water or uranium-235. However, supported by government aid in a number of forms. no uranium-235 separation plant has been built on Only a single, unified, Canadian effort will be large any scheme approaching a commercial basis. When enough to survive as a separate identity. and if this is done, the cost of a separative work unii will increase substantially.

Electrical Energy Research and Development With its heavy-water plants, Canada is the first country to experience the problems of commer- In the long term, the development strategy that cializing isotope separation. These plants are so AECL should adopt seems to be clear—to exploit capital intensive and meet such a basic requirement, the CANDU reactor potential to its economic limits that utility-type financing and operation will and to exploit any nuclear energy development that probably prove to be more appropriate than the promises cheaper electric power in which it can normal chemical industry practice. establish a favourable position through its unique A number of countries now have, or are planning, skills, facilities or ideas. investments in large chemical plants for extracting Due to the long-term increasing importance of Plutonium and uranium from irradiated fuel. The electricity in the total energy picture, it is probable alternatives for Canada are to store irradiated (i.e. that Canada should undertake more research and spent) fuel from CANDU reactors, sell it for its

30 plutonium content, have it processed elsewhere and in context with that of the world. Atomic sell or use the plutonium, or build a Canadian plant Energy of Canada Limited, Report AECL-4254 and sell or use the plutonium produced. To date 8p. 1972. irradiated fuel has been sold for reprocessing outside the country. 9. Merlin, H.B. (On behalf of Canadian Nuclear Association Economic Development Committee) Work is in hand to assess the value of plutonium Nuclear Energy: its growth and impact. Paper for use in CANDU power reactors and the poten- 71-CNA-301, presented at Canadian Nuclear tialities for a chemical plant in Canada. Future Association 11th Annual International Confe- chemical plant costs and the market value of rence, Montreal, 1971. plutonium are difficult to estimate. However, the exploitation of the CANDU system is independent of 10. Howieson, J. The Canadian nuclear industry. 4 th anv investment decision on this matter. Int. Conf. Peaceful Uses Atomic Energy, Paper A/CONF.49/A/155, lip. 1971. Atomic Energy of Canada Limited, Report AECL-3978.

11. Perryman, E.C.W. Canadian power reactor program — present and future. Presented 27th 12. REFERENCES Annual Congress of Canadian Association of Physicists, Alberta. Atomic Energy of Canada Limited, Report AECL-4265, 9p. 1972. 1. World energy requirements and resources in the year 2000. 4th Int. Conf. Peaceful Uses Atomic Energy, Paper A/CONF.49/P/420, 20p. 1971. 12. MacKay, I.N. The Canadian NPD-2 nuclear power plant. 2nd U.N. Int. Conf. Peaceful Uses 2. Weinberg, Alvin ML, and Hammond, R.P. Global Atomic Energy 8: 313-321, Paper A/CONF. 15/ effects of increased use of energy. 4th Int. Conf. P/209. 1958. Atomic Energy of Canada Limited, Peaceful Uses Atomic Energy, Paper Report AECL-619. A/CONF.49/P/33, 8p. 1971. 13. Woodhead, L.W., and Brown, W.M. Problems and 3. Mandel, H. Resources of primary energy. 4th Int. performance of NPD. 3rd U.N. Int. Conf. Peace- Conf. Peaceful Uses Atomic Energy, Paper ful Uses Atomic Energy 5: 131-322. 1964. A/CONF.49/P/359, 27p. 1971. Atomic Energy of Canada Limited, Report AECL-2008. 4. Bell, E.S. (Canadian National Energy Board) The pressure of limited resources and rising demand 14. Lewis, W.B., and Foster, J.S. Canadian operating for energy. Presented at Conference of Science experience with heavy water power reactors. Writers, Ottawa, 1972. Report presented (condensed version) at i. American Power Conference, Chicago. Atomic 5. Williams, R.M., et al. Uranium and thorium in Energy of Canada Limited, Report DL-101. 4Hp. Canada: resources, production and potential. 4th 1970. Also Report AECL-3569. Int. Conf. Peaceful Uses Atomic Energy, Paper 15. Fairlie, J.N. Douglas Point Nuclear Generating A/CONF.49/A/154, 19p. 1971. Atomic Energy Station. Atomic Energy of Canada Limited, of Canada Limited, Report AECL-3977. Report AECL-1596, 94p. 1962. 6. Round, K.J. Isotope energy source development 16. Woodhead, L.W. et al. Commissioning and opera- at Commercial Products. Atomic Energy of ting experience with Canadian nuclear-electric Canada Limited, Report AECL-3911, p. 27. stations. 4th Int. Conf. Peaceful Uses Atomic 1971. Energy, Geneva, Paper A/CONF.49/A/148, 18p. 7. Round, K.J. Radioisotope power development at 1971. Atomic Energy of Canada Limited, Report AECL, Commercial Products. Atomic Energy of AECL-3 97 2. Canada Limited, Report AECL-4301, p. 2-4. 17. Moon, C.L. Pickering Generating Station, p. 1972. 501-505; Loken, P.C. Core physics, p. 506-507; 8. Mooradian, A.J. Canada's nuclear power program Simmonds, C.A. Mechanical design of the Picke-

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