Heavy water reactors an overview sciencedirect topics. Furthermore, it is important to note that the existing candu reactors can be converted to use thoriumbased fuel with small changes to the design, and the majority of the reactor systems would not. July 21, 1995 investigations following the loss of coolant accident loca at pickering reactor 2 canada on december 10, 1994 have revealed that the written instructions followed by reactor operators actually contributed to the accident. Both a lwrtype scwr with a reactor pressure vessel and a candu type scwr with pressure tubes are being developed. The calandria tubes, made of zircalloy2, are arranged in square arrays in the d 2 o moderator at low temperature candu 6, the candu 9 is essentially a repackaging of the bruce design, so that it can be built as a single reactor unit.
By the early 2000s, sales prospects for the original candu designs were dwindling due to the introduction of newer designs from other companies. Candu fuel is produced in smaller and simpler units than those typical of lwrs, potentially reducing the fabrication cost, which is a substantial fraction of the total cost of mox use. A short history of the candu nuclear power system 1 revision 2, december 2002. As published in the canadian nuclear society bulletin vol. The candu reactor is a canadiandeveloped, pressurized heavy water reactor used for generating electric power. The far future candux, which is not a specific reactor design. Following this successful commercial sale, cge had hoped to expand its. Advantages and disadvantages of hwr or candu type reactor.
The ec6 uses natural uranium as a fuel, a heavywater moderator and heavywater coolant in a pressuretube design. Heat from nuclear fission is passed to a working fluid water or gas, which in turn runs through steam turbines. The candu reactor design is extremely flexible and with much space to improve, since the core had been originally designed to optimize the performance of natural uranium fuel and to achieve high neutron economy. In the book radioactivity, published in 1904, rutherford. Some novel onpower refuelling features of candu stations. Oclcs webjunction has pulled together information and resources to assist library staff as they consider how to handle coronavirus. The moderator is the material in the reactor core that slows down the neutrons released from fission so they cause more fission and sustain the chain reaction. The essential candu is brought to you by unene with administrative and sponsorship support from cog. Investigation of candu reactors as a thorium burner.
The code has been used in the design and analysis of candu 3, candu 6 and candu 9 reactors. Numerous and frequentlyupdated resource results are available from this search. The enhanced candu 6 ec6 is a 700megawatt mwe generation iii reactor based on the highly successful candu 6 reactor, with a number of safety enhancements included to meet the latest canadian and international standards. The present book is an attempt to approach dynamic psa in generic candu 6 reactor design. The enhanced candu 6tm reactor generation iii candu.
Candu designs, a smaller 450 mw candu3 and a larger candu9 in the 900. The heavy water in the moderator system is normally not highly pressurized. The moderator in light water reactors is ordinary water, but the candu heavy water reactor uses heavy water or deuterium oxide, which has a chemical formula of d 2 o. The current design optimized version of the candu reactor is the candu e6 which is available from candu energy inc. To achieve them some new features were introduced and others were improved from the previous candu 6 and candu 9 designs. Aecl has evolved the advanced candu reactor acr design from its highly successful candu6 design.
On the other side, the flexibility of candu reactors to accommodate a large variety. This reactor has a unique design using natural or lightly enriched uranium as the fuel and heavy water instead of light water as a moderator. The candu reactors cooling water tubes are pressurized to 1525 pounds per square inch, lower than pressurized water designs. Candu reactors are now in seven countries and provide approximately 15% of canadas electricity. Nuclear power plant systems and operation candu owners group. Reactor core comprising small diameter fuel channels rather that one large pressure vessel. The reactor, refueling machine, and fuel designs are illustrated and discussed under candu reactor and fuel design. The first step is the design of the reactor itself. A 2010 book includes conceptual design and analysis methods such as core design, plant system, plant dynamics and control, plant startup and stability, safety, fast reactor design etc. Moderator inlet and outlet tubes direct the moderator through the calandria, then to the external heat exchanger for cooling. The candu canada deuterium uranium is a canadian pressurized heavywater reactor. The first candu 6 plants went into service in the early 1980s as leadingedge technology, and the design has continuously evolved since to. Approaching dynamic psa within candu 6 npps paperback may 9. The candu has the ability to refuel while the reactor is still running whereas other reactors must shut down completely, lowering their capacity factor.
Risks of the candu reactor design introduction the candu canada deuterium uranium reactor is a pressurized heavy water reactor of canadian design. All canadian nuclear reactors are of the candu type but the. Candu reactors are designed to be refueled without being shut down. Phwrs frequently use natural uranium as fuel, sometimes very low enriched uranium. The latest, singleunit design of this type is the candu 9, a 935 mwe reactor based on the multiunit darlington and bruce b designs with additional enhancements from ongoing aecl engineering and research programs reference 3. Aecl responded by cancelling candu 9 development and moving to the advanced candu reactor acr design. In addition, we are exploring novel and synergistic candu applications, in hydrogen for.
The candu design requires significantly more plumbing than a pwr reactor, as each pressure tube has high. Candu and similar heavy water reactors could in theory generate additional tritium in a number of ways. Candu reactor article about candu reactor by the free. Nuclear reactor design an advanced course in nuclear engineering oka, yoshiaki, kiguchi, takashi on. Atomic energy of canada limited aecl developed the candu reactor technology starting in the 1950s. Candu nuclear power stations have consistently proven to be competitive with other types of nuclear power plants, while offering unique advantages to their operators. The code has also been used for the design and analysis of the multiple applied lattice experimental maple class of reactors and for the analysis of thermalhydraulic experimental programs conducted by atomic energy of canada limited aecl.
The candu canada deuterium uranium is a canadian pressurized heavy water reactor. Week 2 dynamic characteristics of candu reactors 310 h. Chapter 18 covers alternative fuel cycles that have also been considered for application in the candu reactor. Candu 6 is our 700 mwe class nuclear power reactor. Candus have a number of serious technical, and safety problems, as well as the unique environmental problem of tritium emissions. From candu, it takes the heavy water moderator, which gives the design an improved neutron. Chapter 9 contamination control introduction contamination is radioactive material where it isnt supposed to be. There are 31 candu reactors in operation globally, not including 16 reactors in india that are based on the candu design, but are not technically candus.
The unique fuel and reactor design of candus makes such accidents less likely than at any other type of nuclear generating facility. Cnl is the designer and developer of the canadian deuterium uranium candu reactor. The neutronic calculations are based on a gentillyii design modified to a candu thorium reactor, as described in refs. From candu, it takes the heavy water moderator, which gives the design an improved neutron economy that. The candu 9 9250 mwe was developed from the candu6 also as a singleunit plant. The essential candu is a textbook about nuclear science and engineering pertaining to candu reactors using candu as the reference design. Since there is a smaller fraction of fissile material in natural uranium, a somewhat larger reactor core was needed. It demonstrates the maturity of the candu technology. The book will emphasize theory over other aspects of nuclear science. This record is a remarkable achievement for large construction projects. The history and current state of canadas candu nuclear reactor.
This distinguishes it from comparable textbooks based on pwr reactors. A nuclear reactor, formerly known as an atomic pile, is a device used to initiate and control a selfsustained nuclear chain reaction. Nuclear street nuclear power plant news, jobs, and careers. Like the candu 6, the candu 9 is essentially a repackaging of the bruce design, so that it can be built as a singlereactor unit. The candu 9 uses the same 37element fuel bundle design as the other operating. Reduced project implementation risk for candu 9 has been assured by a thorough program of upfront. The phenomena of the accidents is coupled to the logicprobabilistics of. The research and prototype reactors leading to the candu design are described with some. Subsequently, more general core modelling concepts are presented, including the twostep approach to neutronics calculations. The candu canada deuterium uranium reactor is a pressurized heavy water reactor of canadian design. Some of the design features and unique characteristics of the candu reactor are.
Candu reactors are also used in new brunswick and in numerous export markets. This candu textbook is suitable for students, educators, trainers and working professionals at a target level of senior undergraduate year university engineering and. It combines features of the existing candu pressurised heavy water reactors phwr with features of lightwater cooled pressurized water reactors pwr. Cge had developed this design on the basis of its earlier work in the design of npd. December 31, 1969 every nuclear reactor is a disaster waiting to happen and candu reactors are no exception. The integrated deterministicprobabilistic method is called dynamic psa. All nuclear power plants in canada are powered by candu reactors. Chapter 18 also covers, albeit briefly, some aspects of fuel manu. This was initiated by unene, administered by candu owners group cog and funded by all candu utilities in canada and offshore with prof. Business business, international chemicals, plastics and rubber fuel reprocessing nuclear reactors analysis nuclear fuels nuclear industry production management nuclear power plants plutonium usage pressurized water reactors thermodynamics reactor fuel reprocessing. At a glance, the icb values for all fuel bundle designs are close to each.
No control rods are required, therefore, control is much easier than other types. It can be produced locally, using proven technology. Reasons for the choice of key parameters are given. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Improved incore flux detector assembly for candu reactors. Canadian utilities are no longer building candu reactors because of their high cost and poor performance. The basic operation of the candu design is similar to other nuclear reactors.
Nuclear reactor design an advanced course in nuclear. Phw power reactor fuel bundle design, and describes the various designs. The major advantage of this reactor is that the fuel need not be enriched. The essential candu a textbook on the candu nuclear power plant technology. Heavy water lasts beyond the life of the plant and can be reused candu reactor core design. Chapter 2 genealogy of candu reactors prepared by dr. All canadian nuclear reactors are of the candu type but the reactor has also been marketed abroad until october 2011 aecl marketed and. Furthermore, it is important to note that the existing candu reactors can be converted to use thoriumbased fuel with small changes to the design, and the majority of the reactor systems would not need any modification. Although heavy water flows and transports heat to an extent that is very similar to light water, this is effectively where parallels between fission reactor designs exploiting these substances end. Typically there are two fuel and moderator channel changes during the reactor design working life.
The candu 9 design provides a large reserve water inventory in a torus shaped tank located at high elevation in the reactor building, above the steam generators. Candu heavy water reactors use natural uranium, of which 0. Risks of operating candu 6 nuclear power plants banktrack. Candu 9 design, where extensive modularization of components. The behaviour of transuranic mixed oxide fuel in a candu900. A pressurized heavywater reactor phwr is a nuclear reactor that uses heavy water deuterium oxide d 2 o as its coolant and neutron moderator.
Candu reactors achieve these performance objectives through the use of oxide fuel, pressure tubes, moderator tubes and heavy water as both a moderator and as a primary. May 02, 2017 candu, which stands for canada deuterium uranium, is a pressurized heavy water reactor. It enables those new to candu to learn about candu as an overall system and to pursue specialized topics in depth. Reliable information about the coronavirus covid19 is available from the world health organization current situation, international travel. R9 requirements for emergency core cooling systems for. Candu reactors varies depending on the design of the core, and may range between 180 and 225 mw. This chapter discusses the historical beginnings and evolution of the candu reactor. As a result, a candu reactor has a positive void coefficient of reactivity. Perturbations such as fuelling, power changes, temperature changes, and so on tend to move the. The canadian book on nuclear technology, mcmaster university press, 2002, p. The acronym refers to its deuteriumoxide moderator and its use of uranium fuel. Aseaatom designed a lightwater reactor the pius reactor with novel. Through the 1980s and 1990s the nuclear power market suffered a major crash, with few new plants being.
The candu 6 reactor design has been chosen as a reference and a brief. Natural uranium fuel with online fuelling high localization potential suitability for small and medium sized electric grids superior safety performance and economics a proven design based on the highly successful candu 6 reactors the enhanced candu 6. It had some novel design aspects, including direct injection of emergency. The same design flaws that caused the pickering accident exist at other candu reactors. Candu reactors have common design flow wise international. Aug 21, 2016 the candu reactor is a canadiandeveloped, pressurized heavy water reactor used for generating electric power. Canada has exported candu reactors to argentina, china, india, pakistan, romania, and south korea. Bundle geometry design influence on fuel burnup and performances. The sghwr was developed by the ukaea, being seen as combining the best features of candu and bwr. The basic parts of a nuclear reactor are the core, a moderator, control rods, a coolant, and shielding. Once in the vacuum building, the radioactive steam is condensed into liquid and contained. The ec6 reactor builds on this success of the candu 6 fleet by using the operation, experience and project feedback to upgrade the design and incorporate design improvements to meet current safety standards. Since the early 1990s, six new candu 6 plants were delivered on or ahead of schedule and on budget. Improving the calandria tubes for candu reactors book.
Genealogy of candu reactors september 2016 chapter 2 genealogy of candu reactors prepared by dr. The history and current state of canadas candu nuclear reactor chelsea liekhusschmaltz february 26, 20 submitted as coursework for ph241, stanford university, winter 20. Although the systems at point lepreau are design ed to contain the radioactive materials they process, there are many ways in which these materi als can escape to cause a contamination hazard. Being able to always maintain control of the nuclear chain reaction at all times is very important. The candu reactor consists of the horizontal cylinder called the calandria. Fortunately, the candu s basic design means the rods in ontarios reactors are already surrounded by a huge pool of cool water, says jerry hopwood, vicepresident of product development at. The reactor vessel may be built to withstand low pressure, therefore, the cost of the vessel is less.
Upfront basic engineering continues on the 935mwe candu 9 reactor, a single unit adaptation of reactor units operating in darlington, canada. The candu reactor 9 is a design in which heat is generated from a critical reaction in uranium in a cylindrical vessel on its side. The design working life of a properly maintained candu reactor is 60 years. The heavy water coolant is kept under pressure to avoid boiling, allowing it to reach higher temperature mostly without forming steam bubbles, exactly as for. The acr700 reactor design is based on the modular concept of horizontal fuel channels surrounded by a heavy water moderator, the same as with all candu reactors. It had flexible fuel requirements which have been taken forward to the ec6. An even number of fresh fuel bundles are inserted into the channel by the machine at. The design uses heavy water which contains primarily the element deuterium and the main fuel type is uranium. This book focuses on core design and methods for design and analysis. Chapter 9 contamination control candu owners group. It is demonstrated that the prescnt candu design concept has potential for increased conversion and resource utilization compared with other reactor concepts. Aecl is currently offering a new version of the candu design concept, known as the acr.