~ A Primer ~
TEXT: Gordon Edwards
PHOTOS: Robert Del Tredici
TABLE OF CONTENTS
- Uranium Tailings
- Port Hope Wastes
- Miscellaneous Radwaste
- High Level Waste
- Decommissioning Wastes
- Nuclear Lab Wastes
- Research Reactors
- Isotope Production
- Food Irradiation
- District Heating Reactors
- Geologic Disposal
- High Level Liquid Radwastes
- Plutonium (MOX) Fuel
This shovel digs uranium ore from the Gaertner Pit at the Key
Lake open-pit uranium mine in Northern Saskatchewan.
Uranium is a naturally occurring radioactive metal. It has two principal uses: nuclear bombs and nuclear electricity generation. These uses are not mutually exclusive. In recent years, uranium has also been used as armour for tanks, bullets and artillery shells.
Canada was the first country to mine uranium. The world's first uranium mine was at Port Radium, NWT, on the shore of Great Bear Lake. Canada was also the first country to refine uranium on an industrial scale. Uranium for the World War II Atomic Bomb Project was processed in secrecy at Port Hope, Ontario.
Much of the uranium for the Cold War nuclear arms race came from Canada: Port Radium and Rayrock, NWT; Uranium City, Saskatchewan; Bancroft and Elliot Lake, Ontario. By 1960 the American military contracts had been terminated. All uranium mined in Canada since 1965 has been sold for reactor fuel.
Canadian uranium miners have died from lung cancer at a rate many times higher than non-miners. Ottawa knew of the health dangers of uranium and radium as early as 1932, but did not begin to inform workers or compensate their widows until 1973. An epidemic of cancer deaths among men of the Sahtu-Dene tribe from Deline, NWT, who carried sacks of radioactive concentrates on their backs for decades, is currently under investigation by authorities.
Canada remains the world's largest producer and exporter of uranium. Since the mines at Uranium City and Elliot Lake have been closed, all Canadian uranium now comes from rich deposits located in the Athabasca Basin of Northern Saskatchewan.
Canada exports uranium all over the world. Major buyers have been the U.S., Japan, Germany, France, Sweden, and Spain. Less than twenty percent of Canada's uranium is used domestically.
Countries buying Canadian uranium must promise not to use it for weapons. But there is evidence that some of this uranium still finds its way into bombs.
Uranium is widely distributed in the earth's crust, but is concentrated in certain rock formations. In the case of surface deposits, uranium ore is dug from open pits. Deeper deposits require underground mining techniques.
Close to each mine is a mill which crushes the rock and separates out the uranium. Most of the pulverized rock stays behind as radioactive sands and slimes called tailings which remain hazardous for hundreds of thousands of years.
The extracted uranium, called yellowcake, undergoes many chemical transformations. In Canada, it is first trucked to Ontario, where refineries at Blind River and Port Hope work in tandem to convert yellowcake into
Uranium hexafluoride (hex) is a compound of uranium that becomes a gas when heated. In gaseous form, it can be "enriched". Enriched uranium is needed for research reactors, most non-Canadian power reactors, and bombs. Uranium enrichment is a sophisticated technology -- and a strategic one, since it can be used to make nuclear explosives. All nuclear weapons states have enrichment plants. Canada does not.
- uranium dioxide, used domestically as fuel for CANDU reactors, or
- uranium hexafluoride, exported for enrichment and subsequently used as fuel for non-CANDU reactors.
That is why Canada exports uranium in the form of "hex". It is sent first to a nuclear weapons state (the U.S., U.K., France, or Russia) for enrichment, and thence to an overseas customer for use as reactor fuel.
For every six pounds of uranium that enters an enrichment plant, only one pound is sent to the customer as enriched fuel. The remainder, called depleted uranium, is discarded, having no significant peaceful use. But it has important military applications. Depleted uranium is used to make plutonium triggers for nuclear weapons. It is also used to reinforce armoured vehicles and to make conventional shells into armour-piercing ones.
This glass ball is the exact size of the plutonium core in
the bomb that destroyed Nagasaki on August 9, 1945.
Plutonium is the primary explosive in most nuclear weapons. It is an artificial element, created inside any reactor that uses uranium fuel. The first reactors were built in the U.S. in order to produce plutonium for bombs.
During World War II, Canada was on the cutting edge of plutonium research. Top level scientists from England, France and Canada worked at a secret laboratory in Montreal to demonstrate the most efficient methods for producing and extracting plutonium.
This work led to a top level military decision in Washington, in 1944, to build Canada's first heavy water reactors. Canada selected Chalk River, Ontario, as the site to manufacture plutonium and explore other applications of nuclear energy. A pilot plutonium extraction plant was built and operated there.
The French and British nuclear weapons programs grew out of the Canadian work. The first British nuclear weapons test in 1952 used plutonium metal from Chalk River. The Windscale plutonium extraction plant in England was designed using Chalk River data. For over twenty years, Chalk River sold plutonium to the U.S. bomb program to help defray the escalating costs of Canadian nuclear research.
Any country purchasing a reactor or uranium from Canada promises not to use the resulting plutonium for bombs. However, once plutonium is created, it remains weapons usable for thousands of years -- long after the reactors are gone and the agreements forgotten.
In 1974 India exploded its first atomic bomb using plutonium from a research reactor received as a gift from Canada. Most of India's plutonium is produced in clones of Canadian reactors. India has also begun to stockpile tritium, a powerful explosive used in advanced weapons, from its CANDU clones.
All of Canada's other reactor customers -- Pakistan, Taiwan, Korea, Argentina, Romania, and China -- have either acquired a nuclear weapons capability or have considered embarking on a program to do so.
In 1996 Prime Minister Jean Chrétien announced that Canada is in favour of importing 100 tons of plutonium from dismantled Russian and American warheads to be used as fuel in Ontario's reactors. Proponents say this will make the world safer by reducing the amount of weapons plutonium, thus turning "swords into ploughshares". Critics say it will stimulate the use of plutonium as a fuel worldwide, making it even more accessible for bombs.
For decades, nuclear advocates have predicted that plutonium will replace uranium as fuel for reactors; they see it as the principal energy source of the future. Japan, Germany, France, Russia, India, and the U.K., have plans to use plutonium fuel on a routine basis. Civilian stocks of plutonium are already larger than military stocks, and are growing faster. This is troubling, since six kilos of plutonium -- about the size of a grapefruit -- is enough to make a powerful nuclear weapon.
Before plutonium can be used for any purpose, it has to be extracted from spent nuclear fuel. This must be done robotically in a reprocessing plant; irradiated fuel is dissolved in acid, and plutonium is separated out. The highly radioactive liquid waste remains behind.
Once extracted, plutonium can be used for bombs or fuel -- so states with reprocessing plants or plutonium fuel are close to having a nuclear weapons capability. And terrorists can make bombs from stolen plutonium.
CANDUs produce more plutonium than other power reactors. It is harder to determine if plutonium is being removed from a CANDU, as the fuel bundles are compact and can be removed from the core without shutting the reactor down. Canada depends on the pledged word of its clients to prevent military use of plutonium.
Canada is not against the use of plutonium as fuel; in fact, Ottawa is keeping open the option of commercial reprocessing in Canada. Nor is Canada against nuclear weapons, as shown by its membership in NATO, which has a "first use" nuclear weapons policy in case of need. Developing countries deplore this double standard.
This wall of uranium tailings, visible behind the trees, is
radioactive waste from the Stanrock mill near Elliot Lake, Ontario.
There are 200 million tons of sand-like uranium tailings in Canada, mostly in Ontario and Saskatchewan. These radioactive wastes will remain hazardous for hundreds of thousands of years. They contain several of the most powerful carcinogens known: radium, radon gas, polonium, thorium and others. Radioactive tailings also result from milling phosphate and other ores that are rich in uranium.
In 1978, an Ontario Royal Commission recommended that a panel of world class ecologists study the long term problem of safely containing radioactive tailings, and that the future of nuclear power be assessed in view of their findings. The government has ignored these recommendations.
Port Hope Wastes
In 1975, St. Mary's School in Port Hope was evacuated because of high radon levels in the cafeteria. It was soon learned that large volumes of radioactive wastes from uranium refining operations had been used as construction material in the school and all over town. Hundreds of buildings were found to be contaminated.
Other problems came to light: three waste dumps leaking radioactivity, a radioactive public beach, radioactive wastes dumped in the harbour and radioactive materials abandoned in open ravines around town. In all, 800,000 tons of radwaste were identified for removal from Port Hope to be stored elsewhere.
A federal Task Force spent eight years looking for a site for these wastes. Deep River, the bedroom community of Chalk River Laboratories, was the only candidate site to emerge. However, the federal government's refusal to guarantee jobs for the nuclear scientists at Chalk River resulted in a rejection of the deal in 1997. By default, the nuclear wastes remain at Port Hope.
Radioactive mops, rags, clothing, tools, and contaminated equipment such as filters and pressure tubes, are stored in shallow underground containers at the Bruce Nuclear Complex and elsewhere. An incinerator is used to reduce the volume of combustible radwaste materials.
High Level Waste
Over 99 percent of the radioactivity created by a nuclear reactor is contained in the spent fuel. An unprotected individual standing one metre from a CANDU fuel bundle just out of the reactor would receive a lethal dose in seconds. This intensely radioactive material is called high level nuclear waste.
Spent fuel contains hundreds of radioactive substances created inside the reactors: (1) when uranium atoms split, the fragments are radioactive; these are the "fission products"; (2) when uranium atoms absorb neutrons without splitting, they are transmuted into "transuranium elements" such as plutonium, americium, and curium.
Due to the presence of these toxic materials, spent fuel remains extremely dangerous for millions of years.
Structural materials in the core of an operating reactor become radioactive from neutron bombardment. The cost of dismantling such a radioactive structure approaches the cost of building it in the first place.
Current plans are to wait forty years, then use underwater cutting techniques to minimize radiation exposures to the workers. Hundreds of truckloads of radioactive rubble will result from each dismantled reactor.
Nuclear Lab Wastes
Chalk River has many waste problems: six underground tanks of high level radioactive liquid waste, a spent fuel pool which has leaked for 30 years, pits where isotopes have been dumped for decades, radioactive parts of damaged reactors buried on site, and a "dispersal area" where millions of gallons of radioactive liquids have been poured into shallow trenches near the Ottawa River.
The Whiteshell Nuclear Research Establishment has likewise created so much radioactive contamination that it will be expensive to close down. The Auditor General reports that Atomic Energy of Canada Ltd. (owner of both labs) has not properly accounted for the cost of restoring these sites. Ottawa is now trying to privatize Whiteshell.
This underground chamber at Lac du Bonnet, Manitoba,
was excavated to test pre-Cambrian granite as a possible
permanent repository for high-level radioactive wastes.
Scientists employ research reactors to study the atomic properties of matter. In addition, samples irradiated in a nuclear reactor become radioactive, making highly precise chemical analyses possible.
Radioactive isotopes are produced in abundance inside reactors ; some are sold for use in medicine, industry, and scientific research. Canada is the world's largest supplier of molybdenum-99 & cobalt-60.
In addition to the large research and isotope production reactors at Chalk River, several universities in Canada have their own small research reactors.
In an effort to find new markets for isotopes, the Canadian nuclear industry is promoting the use of intense radiation from cobalt-60 to kill insects and microbes in spices, fruit, poultry, grain and other foodstuffs. The purpose is to prolong shelf life. A similar technology is used to sterilize medical equipment.
A Parliamentary committee recommended against the use of food irradiation without further study. Irradiation creates new chemical substances (radiolytic products) in the food, some of which are carcinogenic. Children fed irradiated wheat have shown chromosome damage. As well, irradiating food reduces the vitamin content.
The industry proposes that irradiated food be labeled inconspicuously to minimize consumer anxiety.
District Heating Reactors
Small reactors can be used to provide hot water or steam to heat a group of buildings. At Whiteshell, a prototype district heating reactor was built but never licensed for full power operation. Two universities -- in Québec and Saskatchewan -- refused AECL offers of free district heating reactors because of unresolved problems associated with the technology. Canadian research on such reactors has since been suspended.
At AECL' s Underground Research Laboratory (URL) in Manitoba, a shaft was sunk 500 meters into the hard rock of the Canadian Shield and underground chambers were excavated. The nuclear industry has advocated irretrievable storage of high level radioactive waste in hard rock.
A federal panel has advised Ottawa not to implement this proposal, since it is not acceptable to Canadians and it is not proven safe. Manitoba has outlawed the import of high level radwaste for burial.
High Level Liquid Radwastes
Scientists at Whiteshell have studied the solidification of high level radioactive liquid waste left over from reprocessing spent nuclear fuel.
Nuclear proponents anticipate that plutonium will be extracted from spent fuel before the waste is placed in geologic disposal. For this reason, they define "nuclear fuel waste" to be either (1) unreprocessed fuel bundles or (2) solidified post-reprocessing waste.
At Chalk River, there are six underground tanks of high level radioactive liquid waste left over from reprocessing operations carried out in the late 1940s. Some of this liquid waste was cast into glass blocks and buried in sandy soil near the Ottawa River; it was the world's first liquid radwaste solidification pilot project.
Chalk River operated a pilot plutonium fuel fabrication line for years, planning for the day when plutonium fuel would become standard. These plans were given reduced priority when U.S. President Carter opposed reprocessing on global security grounds. President Clinton has since adopted a similar policy perspective.
But Canada still keeps the plutonium fuel option open. In 1997 plutonium from dismantled American and Russian warheads was approved for testing as reactor fuel at Chalk River. If the test goes well, 100 tons of weapons plutonium may be imported into Canada over 25 years.
Spent nuclear fuel is extremely radioactive; as a result, it spontaneously generates a form of heat called "radioactive decay heat".
Spent fuel pool at the Gentilly-2 CANDU
reactor across the St. Lawrence River
from Trois-Rivières, Québec
RADIOACTIVE DECAY HEAT
Used fuel bundles removed from a CANDU reactor must be cooled in pools of circulating water for at least seven years. During that time, if cooling water were to become unavailable for a protracted period, the spent fuel would overheat and its metallic cladding would rupture, releasing radioactive gases and vapours.
Every nuclear power reactor has one or more spent fuel pools to accommodate its high level radioactive waste.
Dry spent fuel storage silos, outdoors,
at Point LePreau, New Brunswick
RADIOACTIVE DECAY HEAT
After years of wet storage, CANDU spent fuel bundles can be moved into dry storage silos to make room for additional waste in the pools.
The fuel bundles are still intensely radioactive, and they must be handled robotically; but the radioactive decay heat has now subsided enough so that the fuel can be cooled by the unforced circulation of air through vents in the silos. Blockage of the natural air flow would cause a temperature rise inside the concrete containers.
Dry storage is another interim measure, made necessary by the lack of a permanent solution to the long term radioactive waste storage problem.
Underground chamber at Lac du Bonnet, Manitoba,
for testing the concept of geologic disposal of spent fuel
RADIOACTIVE DECAY HEAT
Once spent fuel has been cooled for ten years or more, the nuclear industry wants to bury it in the Canadian shield; but an environmental panel has recently recommended against proceeding.
If the underground repository is sealed, radioactive decay heat can no longer be removed; so it will be absorbed by the surrounding rock. The rock formation in which the fuel is stored will increase in temperature, reach a peak, and then gradually return back to its original ambient temperature. This so-called "thermal pulse" could create new cracks in the repository, accelerating the leakage of radioactive materials.
Atomic Energy of Canada Limited predicts that the thermal pulse from burying spent CANDU fuel in the Canadian Shield will last 50,000 years. The pyramids of Egypt are 5,000 years old.
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