Atomic Energy of Canada Limited ADVANCED HWR POWER PLANTS DL-11O by W. BENNETT LEWIS Paper presented at the American Nuclear Society Power Division Conference Atlantic City, New Jersey 22-24 August, 1972 Chalk River Nuclear Laboratories Chalk River, Ontario November 1972 AECL-4304 PL-110 ATOMIC ENERGY OF CANADA LIMITED ADVANCED HWR POWER PLANTS by W. Bennett Lewis Paper presented at the American Nuclear Society Power Division Conference Atlantic City, New Jersey 22-24 August, 1972 Chalk River, Ontario November 1972 AECL-4304 DL-110 ADVANCED HWR POWER PLANTS1 by W. Bennett Lewis ABSTRACT Heavy-water reactors that are near-breeders can be alternatives for fast breeder reactors with the capability of meeting all the world's needs for power for many centuries. The Canada Deuterium Uranium (CANDU) and Steam-Generating Heavy-Water (SGHW) reactors are the only types of heavy-water reactor established for high-power generating stations. Those CANDU reactors now operating and under construction in large unit sizes are fuelled with natural uranium and cooled and moderated with D20, meeting the requirements of utilities desiring a minimum of enrichment together with an attractive capital cost. Possible modifications to design are the use of boiling light water as coolant, organic coolant, and thorium fuel cycles. Heavy-water reactors have a worldwide distribution. They can be classified as follows: 1) zero energy lattice and reactor physics research reactors; 2) high flux materials test, neutron beam and isotope production reactors; 3) engineering test reactors with high temperature loops; 4) demonstration power reactors; 5) prototype power reactors; and 6) commercial power reactors. Operating experience with the large 540 MW(e) commercial units in Canada has been extremely satisfactory. 1 Paper presented at the American Nuclear Society Power Division Conference, Atlantic City, New Jersey, 22-24 August, 1972. Chalk River, Ontario November 1972 AECL-4304 DL-110 Centrales a eau lourde avancees1 par W. Bennett Lewis Resume Les reacteurs a eau lourde quasi-surgenerateurs peuvent concurrencer les reacteurs surgenerateurs rapides, car ils ont le potentiel voulu pour repondre aux besoins en energie du monde entier pour des siecles a venir. Les reacteurs CANDU (Canada Deuterium- Uranium) et SGHW (Steam-Generating Heavy-Water) sont les seuls types de reacteurs a eau lourde etablis pour les grandes centrales electronucleaires. Les reacteurs CANDU actuellemont en service ou en construction pour de grandes centrales sont corpus pour utiliser de I'uranium naturel comme combustible et de I'eau lourde comme moderateur et com me caloporteur. Ces reacteurs respondent aux exigences des fournisseurs d'electricite qui veulent un minimum d'enrichissemcit et de raisonnables depenses en immobilisation. Les modifications susceptibles d'etre apportees a la filiere CANDU sont: 1'emploi d'autres caloporteurs (eau legere bouillante ou liquide organique) et l'adoption du thorium dans les cycles de combustible. On trouve des reacteurs a eau lourde dans le monde entier. On peut les classer de la facpn suivante: 1) reacteurs de rechevches sur la physique des reacteurs ayant un reseau a energie nulle; 2) reacteurs pour la production d'isotopes, la formation de faisceaux neutroniques et 1'essai des materiaux en haut flux; 3) reacteurs pour les essais technologiques munis de boucles a haute temperature; 4) reacteurs de puissance en demonstration; 5) reacteurs de puissance prototypes et 6) reacteurs commerciaux de puissance. Une experience extremement satisfaisante a ete acquise au Canada dans le fonctionnement des grandes centrales commerciales a eau lourde ayant une puissance electrique de 540 megawatts. 1 Communication presentee au Congres de 1'American Nuclear Society, tenu a Atlantic City, New Jersey, du 22 au 24 aout 1972. L'Energie Atomique du Canada, Limitee Chalk River, Ontario Novembre 1972 AECL-4304 ADVANCED HWR POWER PLANTS by W. Bennett Lewis Advanced heavy-water reactor power plants are with light-water-reactors, would continue for a now established. Ths largest commercial station considerable time to prodrce plutonium for their use. already has an in-service capacity of 1,536 MW(e) net A further 512 MW(e) unit is due to be added next year and is on schedule. I have been pointing out for ten years or more that advanced heavy-water reactors could supply econotnic nuclear power to meet all the world's needs for very many centuries. The extent to which they will be developed and applied depends on the nature of the competition. There are, we know, large-scale plans to introduce fast breeder reactors, but over the next century if they are introduced, they seem likely to depend heavily on other types of power reactor for their plutonium fuel. This was illustrated by J.R. Dietrich in Fig. 1, which he presented at the Winter Meeting of the American Nuclear Society in 1966. His curves relate to the USA but tbe world situation Figure 1 is similar, with only the capacities increased by a factor of 2 or 3. To check in on his projected nuclear On the other hand, as I have said before, if the fast capacity, note that in 1980 his figure was just short breeder reactor is not an economic success, nothing of 100,000,000 kW, whereas now the USAEC very serious happens, provided that other advanced estimate is about 140,000,000 kW. Dietrich's postu- neutron economical nuclear power plants have been late was that in 1985 all the accumulated inventory introduced and carry on. There would, however, be of plutonium from the power reactors was committed no longer a special requirement for plutonium and to fast breeders. Focusing attention on the middle there seems a very strong probability that the con- curve for the 20-year doubter, we note that verter reactors would operate on the thorium- 40,000,000 kW was to come into operation in 1985. ranium-233 cycle which in the long term is most Large, but I suppose not impossible. Thereafter the economical for thermal neutron reactors. breeder curves show their growth if they derive their I am emphasising that the heavy-water power inventory solely from their own operations, then they plants are being developed and built not merely as would uinount to only a very small fraction of the an interim measure before fast breeder reactors are total nuclear power. For example, in the year 2005, established, but in their own right and, in the limit, to the curve shows 80,000,000 kW from the fast supply power and recycled fuel for all the energy breedfir, which is only 8% of the total projected needs that may arise in the world. nuclear capacity. The slope of that projected nuclear capacity is still greater than that of the 20-year In this context neutron-economical reactors doubter, so that the fraction provided by the 20-year command special attention. All the CANDU family of doubler would become even smaller. It is more reactors, whether cooled by heavy water, boiling light realistic to suppose that if the fast breeder reactor is water, or organic coolant, belong essentially to the an economic success, heavy-water-reactors, together neutron-economical or near-breeder class. They -1- promise especially well in association with the (3) Engineering Test Reactors with High Temperature helium-cooled high temperature graphite moderated Loops reactors which benefit especially from uranium-233 (4) Demonstration Power Reactors fuel and a thorium cycle. It is encouraging to note (5) Prototype Power Reactors that many million kW capacity of such high tempera- ture reactors seem likely to be built in the next (6) Commercial Power Reactors Operating or Under twenty years. When associated with such reactors the Construction at June 1972 special merits of the heavy-water reactors are their The lists omit the Savannah River Reactors, DAPHNE efficient use of uranium-235 or even low enriched the Handmaiden Reaclor, Core II of the EBWR and uranium for initiating the production of uranium- at least one of the USSR experimental reactors. Some 233, for example in the cycle 1 have called the others may have been omitted unintentionally. In valubreeder.(l) each list the reactors appear roughly in the order of Heavy-water-moderated reactors have a long and their commissioning. To those who have followed worldwide history. The list of such reactors is too their fortunes their names may serve to recall long even to recite their names here. Many of them memories of international visits and collaboration. have been multipurpose and there is perhaps no Those who have become narrowly embedded in the better example than the Canadian NRX reactor that fates and fortunes of other types of nuclear reactors has recently passed its 25 year jubilee going strong may take away just an impression of their wide range, and still generating information for power reactors in geographical distribution and their continuing intro- mcny families. For example, a paper by R.C. Daniel duction. on Dimensional Changes in Zircaloy-4 Tubing from Of most interest here will be the last three lists of Admiral Rickover's Light Water Breeder Development the Demonstration, Prototype and Commercial Power Program appeared in May in the ANS Journal Nuclear Reactors. Ontario Hydro as the owner-operator and Technology reporting work in an NRX loop. Another Atomic Energy of Canada Limited as the nuclear loop carries organic liquid coolant in work towards designer are more than satisfied with the first year of heavy-water-moderated organic-cooled power reactors. NRX received a new calandria for its core in operation of the Pickering Nuclear Genorating Station 1953 after melting some metal fuel in a power near Toronto. The most encouraging feature shown excursion. Us fuel has changed from natural uranium on List 6 has been the successive reduction in time metal, through natural UCK with enriched boosters to from first critical to achieving "In-service" rating.