Information Papers

Japanese Waste and MOX Shipments From Europe

(August 2007)

Reprocessing arrangements

A total of ten Japanese electric utilities had contracts with the French company Cogema (now Areva NC) to reprocess their used fuel. These Reprocessing Service Agreements date from 1977-78. Other contracts were with British Nuclear Fuels Limited, - BNFL, now British Nuclear Group in UK. About 40% of the used fuel involved was reprocessed by Cogema/Areva and the rest by BNFL/BNG.

After the used fuel had been in storage for some time at the reactor site, it was shipped to France or UK, usually via the Panama Canal, for reprocessing. There were over 160 such shipments in total.

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. Separated high-level wastes - about 3% of the used fuel - remain.

Some 2940 tonnes of the used fuel was shipped by these utilities to France for reprocessing over 1969-90.  Shipments of about 4100 tonnes were to the UK, and by mid 2007 more than 2600 tonnes of oxide fuel had been reprocessed there, plus a small amount of Japanese Magnox fuel.

All the high-level waste from reprocessing the used fuel in France has now been shipped back to Rokkasho in Japan for long-term (30-50 year) storage prior to ultimate disposal. Waste shipments from the UK will be over 2008-16.

Reprocessing of Japanese used fuel in France finished in 2004, and full-scale operation of the new reprocessing plant at Rokkasho-mura is scheduled to start in 2007. Used fuel has been accumulating there since 1999 in anticipation of its operation.

Japan has a small (210 tonnes/year) reprocessing plant already in operation at Tokai, associated with the Monju fast neutron reactor. A much larger reprocessing plant has been built at Rokkasho.

Return of high-level wastes

In February 1995 the first of 12 shipments of vitrified high-level waste (HLW) departed from France for Japan. The last was in 2007. This waste belonged to the ten Japanese power utilities who are responsible for its safe storage and eventual disposal.

The twelve waste shipments over 12 years total 1310 canisters containing almost 700 tonnes of vitrified high-level wastes. These are packed in heavy steel shipping casks (see below).

 

Year of shipment
Number of HLW canisters
from France
1995
28
1997
40
1998
60
1999
40 + 104
2000
192
2001
152
2003
144
2004
132
2005
124
2006
164
2007
130
total
1310

Late in 2008 shipment of the vitrified high-level wastes from UK back to Japan will commence and require about 11 shipments over eight years. Some of this HLW will be substituting for a larger volume of intermediate-level wastes, on the basis that a radiologically-equivalent amount of HLW can be substituted in order to minimise the volume shipped. Both UK and Japan have legislation allowing this.

Return of plutonium and MOX

So far one shipment of separated reactor-grade plutonium recovered from used fuel reprocessing has been returned to Japan, in 1993. This was reactor-grade material, with about 30% Pu-240 in it and therefore useable only as a reactor fuel. It is not suitable for nuclear weapons.

Further plutonium is being returned as 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. The 1999 shipment was returned to the UK due to doubts about quality control.

The origin of High-Level Wastes in the nuclear fuel cycle

Enriched uranium oxide 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 used 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 used fuel as waste. These countries, notably USA and Sweden, therefore aim to store used 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% of the quantity as high-level waste, which includes almost all of the radioactivity from the used fuel.

Vitrification of separated waste

To enable safe storage and transport, the separated high-level waste is mixed with molten borosilicate glass and poured into 1.3 metre 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 litres of glass weighing 400 kilograms. Some 14% of the content is high-level waste derived from the reprocessing of about two tonnes of used fuel. After storage for several years, the thermal output of each canister as shipped is less than 1.5 kilowatts.

Marine transport

The half-tonne 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 tonnes. 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, each of about 500 kg.

The ships involved are 104-metre, 5100 tonne, specially designed double-hulled vessels used only for the transport of nuclear material. The ships belonging to a British-based company Pacific Nuclear Transport Ltd (PNTL), have been approved for the transport of vitrified residues, and conform to all relevant international safety standards, notably one known as INF-3 (Irradiated Nuclear Fuel class 3) set by the International Maritime Organisation.  This allows them to carry highly radioactive materials such as high-level wastes, used nuclear fuel, mixed-oxide (MOX) fuel, and plutonium.

They have completed more than 170 shipments and travelled over 8 million kilometres in the 30 years to 2007 without any incident involving a radioactive release. PNTL is now owned by International Nuclear Services Ltd (INS, 62.5%), Japanese utilities (25%) and Areva (12.5%). It is currently renewing its fleet. INS is 51% owned by Sellafield Ltd and 49% by the UK's Nuclear Decommissioning Authority, and managed by Sellafield Ltd.

 

See also paper on Transport of Radioactive Materials

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 endeavours 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. Japan plans to have one third of its 53 reactors using some MOX by 2010.

The Japanese see this in both commercial and ethical terms, avoiding the depletion of fossil fuels and maximising the utilisation of uranium. More recently the policy has enabled them to commit to significant reductions in greenhouse gas emissions.

From BNFL press release 4 December 1996 (but applying also to MOX shipments):

The companies responsible for the shipments are well-established and well-regarded organizations. The ten Japanese electrical power companies are represented by the Overseas Reprocessing Committee (ORC). BNFL and COGEMA are, respectively, the operators of the British and French reprocessing facilities. All of these organizations have a history of complying fully with the national and international regulations which govern their activities.

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:

The ships are owned by a subsidiary company called Pacific Nuclear Transport Limited (PNTL), which is owned by BNFL (62.5%), Cogema (12.5%) and the Japanese utilities (25%). 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 kilometres 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 tonnes. In the case of spent fuel, each cask typically contains up to eight tonnes 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.

Vitrification conditions the waste into a solid glass form and the highly radioactive nuclear materials, such as caesium, 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 vitrification 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."