The German delegation is seeking to exempt plutonium-uranium "mixed-oxide" (MOX) fuel from a requirement to use a new, improved shipping cask for air transport of radioactive material. The new (Type C) cask is intended to prevent release of intensely toxic plutonium in severe air crashes that existing casks could not survive.
German experts contend the MOX fuel is a "very low-dispersible" material and essentially self-containing. In an air crash, they insist, existing casks are likely to remain sufficiently intact to limit releases of plutonium to an acceptable level. These casks "would only fail substantially in very severe accident conditions," according to a German working paper, which adds, "Serious aircraft accidents are quite rare."
A technical analysis by Nuclear Control Institute finds a number of mechanisms that could result in a dispersal of plutonium in the event of a severe accident. A high-velocity impact that breached the fuel cladding, followed by a fire of moderate temperature that burned for several hours, could cause substantial releases, according to Dr. Edwin Lyman, scientific director. Plutonium is a highly toxic carcinogen, if inhaled.
In 1993, a plan to send MOX fuel rods by air from Germany to Scotland was blocked by Hesse state officials on safety grounds. Currently, MOX fuel fabricated in the U.K. is flown to Switzerland. With the Siemens MOX fuel-fabrication plant at Hanau now canceled, German utilities are contracting with British Nuclear Fuel (as well as Cogema and Belgonucleaire) to fabricate MOX fuel for German power reactors. If the exemption is adopted, this fuel could be flown to Germany in casks designed to survive an impact of 48 km/hr (30 mph) rather than 324 km/hr (203 mph) for the new casks.
The existing casks have been used for land, sea and air tranSport even though the IAEA has advised that "a release of radioactive substances cannot be excluded in the case of a severe aircraft crash involving current packaging."
The U.S. government, in a position paper prepared for this week's Vienna meeting, warns the proposed exemption "negates the original intent for developing [separate] air transport standards." The U.S. paper expresses concern that the allowable radioactive release proposed by the Germans "is not based on any defined model or rationale and that no risk analysis has been conducted on this proposal."
"Commercial rather than safety considerations are obviously behind the exemption request," said Paul Leventhal, president of the Nuclear Control Institute. He cited the official minutes of an IAEA technical consultants meeting last May in which it was stated, "The difficulties...of producing Type C packages and their high production costs were cited as supporting the need for the adoption of the Very Low Dispersible Material (VLDM) concept." Also, a German working paper stated, "The introduction of VLDM-requirements ...takes into account practical transportation needs as well as cost-effectiveness considerations." The authors of the German working paper are officials from the Environment and Reactor Safety Ministry and the Bureau of Radiation Protection.
Beyond the issue of exempting MOX fuel shipments from Type C casks, the adequacy of the IAEA Type C cask itself has been challenged by U.S. and international civil aviation officials. A committee of the International Civil Aviation Organization (ICAO) found that IAEA impact test criteria represented "less than half the energy" required for testing the "black box" flight recorder. The ICAO also found that "the sequence of tests as presently proposed for Type C packagings did not replicate what was likely to happen in an aircraft accident." The ICAO called for sequential impact and fire tests on the same cask rather than the separate impact and fire tests on different casks that are to be required to prove a Type C cask.
Representatives of the International Air Transport Association and the International Federation of AirLine Pilots Associations have called for adoption of the U.S. cask standard, which requires survival of an impact of 464 km/hr (288 mph) and sequential fire testing. No cask has ever been successfully tested to meet these criteria and consequently domestic and international air transports of plutonium are prohibited over the United States.
"It is scandalous that the IAEA is about to sign off on a new air-shipment cask standard that is dictated by commercial plutonium interests, not by the safety interests of innocent people," Leventhal said. "To make matters worse, MOX fuel is to be exempted from this standard, making a mockery of the whole exercise. Unless the German plan is rejected, hundreds of tons of plutonium will be shipped by air around the world in casks that cannot withstand a serious crash. Plutonium flights should not be allowed until there is a crash-proof cask."