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This report examines the possible consequences of a severe yet credible shipping accident in the waters of the Federated States of Micronesia (FSM), for a vessel carrying vitrified high level radioactive waste from France to Japan. Fifteen to thirty (some experts say up to 60) such shipments are planned to take place over the next 15 years. Each shipment will contain at least one cask of vitrified high level waste canisters, though more likely five to 10 casks, with each cask containing nearly 575 times the amount of radioactive cesium and strontium released by the Hiroshima bomb. These shipments of vitrified high-level waste are a result of Japan s desire to stockpile the plutonium (for proposed use as nuclear reactor fuel) reprocessed from their spent nuclear fuel, despite the questionable economic advantage and considerable risk of such an enterprise. The process involves Japan shipping their irradiated or 'spent' nuclear fuel removed from nuclear reactors to France and Britain for reprocessing, and the subsequent shipment back to Japan of the vitrified waste and the separated plutonium.

An accident involving any one of these shipments could have serious health and economic consequences. Ground contamination on the island of Pohnpei would greatly exceed that due to the Chernobyl accident. In the accident scenarios considered here, the additional lifetime risk for an adult of developing cancer ranges from 1.9 chances in 10 to near certainty, depending on the island location. The risk to children would be much greater. We conclude that following the accident the island must be evacuated, food supplies interdicted and the island decontaminated.. Fishing in the area would be off limits.

Although not the most direct route from Europe to Japan, the path around the tip of Africa and through Pacific Oceania is considered likely for political reasons. Japan would like the option of shipping this dangerous material through the Panama Canal and Caribbean Sea, but political pressure from those regions has so far succeeded in blocking this, the shortest route.

Two types of severe accidents are considered: a long duration shipboard fire and a cask buried in ocean sediment. Failure conditions and release rates have been approximated based on the limited available information. The cask which will be used is the TN28VT, which has never been tested to failure, or even under the likely conditions of a shipping accident, which can be more severe than the hypothetical test conditions these casks must withstand. The International Atomic Energy Agency (IAEA) requires the casks to withstand a temperature of 800 degrees Celsius for 30 minutes, yet a shipboard fire can be as hot as 1650 degrees and last much longer; an example is the collision between the Sea Witch and an oil tanker in the New York harbor in 1973, which caused a fire on board the Sea Witch that burned for several days, causing severe damage to below-deck cargo containers.

Release mechanisms for the radioactive materials in the case of a severe accident include failure of the casks "O" ring seals and valves due to heating in a shipboard fire, opening a pathway for gaseous elements to escape, forming a plume of airborne contamination which would disperse and settle over the nearby area, causing soil and water contamination. In the event of a long-duration high temperature fire, radioactive particulates could be released from the cask and settle downwind. In the shipboard fire accident scenario, we estimate a very small percentage release to the atmosphere, approximately 0.03% of the cesium inventory, and a smaller percentage for the other radionuclides.

As an example, we calculate contamination levels and radiation doses at a specific location in Micronesia, the island of Pohnpei. An average diet for citizens of the FSM has been estimated using available information, and doses are calculated according to this diet. Residents of Pohnpei could receive a small radiation dose by inhaling radioactive particulates or by being exposed to gamma radiation from the passing cloud. The major exposures are received from gamma-emitting particulates that are deposited on the ground. Assuming a ship accident one kilometer off-shore and a major fire, the yearly direct gamma dose could range from 35 milliSieverts (mSv) to 350 mSv, depending on a person s proximity to the accident. Dose commitments due to food and fish consumption, calculated separately, add to this radiation exposure. Further, the water supply of Kolonia, the main city on the island, consists of a small open reservoir, that would also become contaminated; this potential dose was not estimated. This accident would result in cancer risks mentioned above and widespread contamination of the island's food, including marine resources necessitating evacuation and 'clean up'.

A cask lost overboard could become buried in sediments, double its internal temperature in tens of hours and over-pressurize, allowing sea water to enter, heat up, and exit as steam, releasing contaminants to the marine environment and leading to human exposure through ingestion of contaminated seafood and contact with contaminated water. In our opinion, this type of accident, leading to a release of all the radioactivity to the ocean environments, may have a higher probability of occurrence since it simply involves a loss of ship and not necessarily an onboard fire.

In addition to its direct health effects, a shipping accident of this magnitude would jeopardize the most important aspect of the FSM s economy; fishing and the sale of fishing rights to foreign fleets. Agriculture and fishing account for 48% of employment, and a majority of the local food supply. Tourism would virtually cease as news of the accident spread worldwide. The loss of tourism and fishing fees alone would correspond to a loss of half Micronesia s income from exports. Agricultural products which account for the other half would be contaminated on the nearby islands as well, and therefore could be considered undesirable by importing countries.

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