Since 1969 there have been over 160 shipments of spent nuclear reactor fuel from Japan to Europe. Reprocessing of the Japanese spent fuel is undertaken in UK and France under contract with Japanese utilities.
Recovered fissile materials are returned to Japan as reactor fuel, notably the mixed-oxide (MOX) fuel shipments in 1999 and 2001. The first shipment to Japan of immobilized high-level waste from reprocessing took place in 1995 and the sixth was in 2000.
In February 1995 the first of a number of shipments of vitrified high-level waste departed from France for Japan. This waste belonged to ten Japanese power utilities who are responsible for its safe storage and eventual disposal.
The 1995 waste shipment was of 28 canisters of vitrified waste, the 1997 shipment was 40 canisters, in 1998 60 canisters, in 1999, 40 and then 104 canisters, and in 2000, 192 canisters were sent. These are packed in heavy steel shipping casks.
Such waste arises from spent fuel which has progressively been shipped by these utilities to France for reprocessing over the last thirty years.
Reprocessing separates the waste, particularly the high-level waste containing nearly all of the radioactivity in spent fuel, from the uranium and plutonium which are recycled as fresh fuel.
A shipment of separated reactor-grade plutonium was returned from France to Japan by sea in 1993 and a shipment of mixed oxide fuel (containing plutonium) was sent in 1999 with a further one in 2001.
The origin of High-Level Waste in the nuclear fuel cycle:
For most of the world's nuclear reactors, uranium oxide concentrate from the mine is first converted into uranium hexafluoride so that it can be enriched.
Natural uranium contains only 0.7 percent U-235 (with 99.3 percent U-238), but this needs to be increased to about 3.5 percent U-235 for use in a nuclear reactor.
After enrichment, the uranium, as an oxide, is made into fuel pellets which are assembled into rods for use in the reactor core.
The fuel stays in the reactor for three or more years during which time it is altered by the fission process. Some of the U-235 is 'burned' and produces energy as heat.
This results in the formation of fission products, - atoms of around half the original atomic weight and which are generally highly radioactive.
Some of the U-238 captures neutrons and through a series of radioactive decay stages, isotopes including Pu-239 and Pu-241 are formed.
These two isotopes, like U-235, are fissile and much of them is 'burned' in the reactor to produce about one-third of the total energy. Some Pu-240 is also formed, along with other transuranic elements (elements of higher atomic number than uranium).
After three years or more these various changes in the fuel assemblies cause the efficiency of the nuclear reaction to be reduced.
Consequently every year or so about one third of the fuel assemblies are removed and replaced by new ones.
The spent fuel is then stored under water in ponds at the reactor site while it cools and the initially intense radioactivity starts to diminish.
A number of countries simply regard this spent fuel as waste. These countries, notably USA and Sweden, therefore aim to store spent fuel for several decades until a lot of the radioactivity has decayed. They then intend to dispose of the fuel elements in an underground repository.
However, several countries, notably Japan, France, Germany and UK, currently reprocess their spent fuel so as to return the useable uranium and plutonium to the front-end of the fuel cycle.
They are then left with about 3 percent of the quantity as high-level waste, which includes almost all of the radioactivity from the spent fuel.
Verification of separated waste: To enable safe storage and transport, the high-level waste is mixed with molten borosilicate glass and poured into 1.3 meter high stainless steel canisters.
The waste becomes locked into the matrix of the glass as it cools, making it stable and resistant to leaching. Lids are then welded on to the canisters to seal them.
Each canister contains 150 liters of glass weighing 400 kilograms. Some 14 percent of the content is high-level waste derived from the reprocessing of about 1.3 tones of spent fuel. The thermal output of each canister as shipped is less than 1.5 kilowatts.
Transport: The half-tone stainless steel canisters containing high-level waste are transported in specially-engineered, heavily shielded steel and resin containers called casks or flasks.
Each weighs about 100 tones. Those used for the high-level waste are very similar to those for transporting the spent fuel from Japan to Europe in the first place, and the MOX on the return voyage. A flask holds up to 28 canisters of vitrified waste.
The ships involved are 104-meter, specially designed double-hulled vessels used only for the transport of nuclear material.
Three ships belonging to a British company associated with BNFL have been approved for the transport of vitrified residues, and conform to all relevant international safety standards.
Reprocessing arrangements:
A total of ten Japanese electric utilities have contracts with the French company Cogema to reprocess their spent fuel. These Reprocessing Service Agreements date from 1977-78. (Other contracts are with British Nuclear Fuels Limited, - BNFL.)
After the spent fuel has been in storage for some time at the reactor site, it is shipped to France, usually via the Panama Canal, for reprocessing.
There have already been over 160 such shipments. All the high-level waste from reprocessing the spent fuel will eventually be returned to Rokkasho in Japan for long-term (30-50 year) storage prior to ultimate disposal.
So far one shipment of plutonium recovered from spent fuel reprocessing has been returned to Japan. This was reactor-grade material, with about 30 percent Pu-240 in it and therefore useable only as a reactor fuel. It is not suitable for nuclear weapons.
In future the plutonium will be returned as a mixed oxide (MOX) fuel, in which the plutonium is mixed with depleted uranium and fabricated into fresh fuel elements ready for use in a power station reactor. Shipments of MOX fuel assemblies were sent in mid 1999 and early 2001. See also UIC briefing paper on MOX.
Japan has a small (210 tones/year) reprocessing plant already in operation at Tokai, associated with the Monju fast neutron reactor. A much larger reprocessing plant is being built at Rokkasho.
Meanwhile Japanese spent fuel is reprocessed by Cogema in France and by BNFL in the UK. Japanese utilities have contracts with these for the reprocessing of some 7000 tones of spent fuel.
A total of more than 3000 canisters of high level waste will be returned to Japan, in about 110 casks. Two thirds of this will be from Cogema and the rest from BNFL.
Japan's Energy Policy: Nuclear power provides about one-third of Japan's electricity, and with the enhanced efficiency brought about by reprocessing spent fuel to recycle the uranium and plutonium, it represents a major part of Japan's endeavors to achieve maximum self sufficiency in energy.
Certainly plutonium is seen as a valuable energy resource, not to be spurned as a source of electricity.
The Japanese see this in both commercial and ethical terms, avoiding the depletion of fossil fuels and maximizing the utilization of uranium.
More recently the policy has enabled them to commit to much greater reductions in greenhouse gas emissions than countries such as Australia.
Japan plans to have one third of its 53 reactors using some MOX by 2010, and has just approved construction of the world's first advanced reactor which will have a complete fuel loading of MOX.
This large reactor will have recycled plutonium as its main energy source and is expected to enter service in 2007.
Ships: The ships on which the nuclear material is transported have a range of safety features far in excess of those found on conventional cargo vessels: Double hulls to withstand collision damage.
Enhanced buoyancy to prevent the ship from sinking even in extreme circumstances Dual navigation, communications, cargo monitoring and cooling systems .
Satellite navigation and tracking Twin engines and propellers and Additional fire fighting equipment, including a hold flooding system.
The ships are owned by a subsidiary company called Pacific Nuclear Transport Limited (PNTL), which is owned by BNFL (62.5 percent), Cogema (12.5 percent) and the Japanese utilities (25 percent).
PNTL is the most experienced company in the world for the sea transport of radioactive nuclear materials with a proven ability over more than 20 years.
The ships have a safety record second to none, having covered more than five million kilometers without a single incident resulting in the release of radioactivity.
Over 4,000 flasks (see below) have been safely transported since the mid-1960s in over 150 shipments.
The ships currently in use were built in the 1980s and undergo regular maintenance inspections and their equipment is regularly checked.
They have a fully trained and experienced British crew and, while at sea, maintain a permanent communications link with a report center which is manned 24 hours a day.
The ships meet the highest safety rating of the International Maritime Organization (IMO), a United Nations agency, which regularly reviews its regulations.
It means that they are amongst the safest ships on the seas. Ships of the same design transport the same type of material within Europe and between ports in Japan.
Casks: Nuclear material is also safely transported extensively within Japan, Europe and elsewhere throughout the world, often involving different modes of transport at different stages of a journey.
For this reason safety is provided by the transport packages, known as casks or flasks, which comply with rigorous international standards - the purpose-built ships therefore provide an extra layer of safety on top of these standards.
Similar casks have been safely transported in the UK, France and Japan for over 30 years.
They are specially designed for the particular radioactive material they carry, give protection to workers and the public against radiation and are designed to withstand the most serious accidents.
The casks are massive steel structures made from 250mm thick forged steel and weigh around 100 tones.
In the case of spent fuel, each cask typically contains up to eight tones of fuel. With vitrified waste, each cask contains 20 or 28 stainless steel canisters which, in turn, contain the solid vitrified glass waste. Each full canister weighs around 500 kg.
The casks are built to standards set down by the International Atomic Energy Agency (IAEA) another United Nations organization.
The regulations which they have established have been agreed by international experts representing 124 member countries of the IAEA.
Under these regulations the cask design has successfully met a series of rigorous fire, impact and immersion criteria.
Verification conditions the waste into a solid glass form and the highly radioactive nuclear materials, such as cesium, are incorporated in, and form part of, the matrix of solid glass.
Even in a scenario of the glass becoming directly exposed to the sea, the leach rate of this special material in water is extremely low.
Independent nuclear experts around the world believe nitrification is the safest and most secure method for treating, transporting and storing highly radioactive waste.
The protection provided by the glass, the cask and the ship ensure that even in very severe accident scenarios the radioactive contents of the waste could not be released into the atmosphere.
Emergency Arrangements: There are hazards in any marine activity and, whilst the safety arrangements are exceptionally good, detailed and well-rehearsed emergency response arrangements also exist.
These range from voyage tracking, sonar location devices, radiation monitoring equipment and a worldwide salvage capability, to an emergency team of industry specialists on 24 hour worldwide standby.
An advantage with transporting this type of material is that the emergency arrangements do not rely on specialist assistance being available from countries adjacent to the route.
There is therefore no special need for emergency plans to be coordinated with other countries in advance.
The material is in a solid form and is characterized by long term stability and low solubility in water so there is no prospect of a 'radioactive slick' or of an atmospheric release.
Even in an extreme scenario, where the material is somehow exposed to sea water, studies have demonstrated that any extra radiation dose to local communities would be tiny - a fraction of natural background radiation. The hazard posed by these shipments is therefore very small.
In the unlikely event of a ship getting into difficulty, a fully trained and equipped team of nuclear experts are available on a 24-hour emergency standby system, in line with IAEA requirements.
In the event of a serious fire or collision, this team would be dispatched to the ship and would direct and manage all remedial operations.
The ship would not necessarily head towards the nearest port to seek assistance. Comprehensive salvage arrangements have been drawn up for both the ship and cargo, which could be initiated immediately.
Routes: Since this type of shipment began nearly 30 years ago, routes have been taken through the Panama Canal, around Cape Horn and around the Cape of Good Hope.
This information is public and has been for many years. Each voyage typically takes six to eight weeks to complete and the ships are capable of completing each voyage without having to stop at any port en route.
As with other merchant vessels, the ship's journey is governed by the United Nations Convention on the Law of the Sea. This allows ships the right of innocent passage and freedom of navigation even within territorial waters (12 miles from a country's coastline).
Under the same law, Exclusive Economic Zones (EEZs) have been established by some states for the exploitation of mineral rights and other economic activities, up to 200 miles from their coastline.
However, it is internationally recognized that there shall be no suspension of the innocent passage of foreign ships within either limit. Under the international Law of the Sea, ships "have the right of unimpeded passage so long as it is continuous and expeditious."
Source: www.uic.com.au
© 2001 Mena Report (www.menareport.com)
