Outwardly, nothing was amiss when a 40-foot-long container was unloaded last February at the Port of Los Angeles after an 11-day voyage aboard the cargo ship Hanjin Mokpo from South Korea.
The container was stacked on the dock, and a day or so later was hauled about 20 miles to a Compton warehouse, where clerks unpacked the cargo, including a battered plywood crate. Soon the crate was loaded on a truck for a three-week, cross-country trip.
It was not until the crate reached its final destination at Amersham Corp., northwest of Boston, that an alarm sounded, warning that the cargo contained potentially dangerous levels of radiation.
The incident touched off a far-reaching federal investigation into how the shipping crate slipped undetected through the harbor, crossed the country by truck and exposed dozens of unsuspecting people to a pellet of Iridium-192, a radioactive isotope typically used to X-ray the strength of industrial welds. It also has rekindled debate over the safety of shipping radioactive materials on the nation's highways.
The crate contained 14 stainless steel carrying cases designed to transport radioactive materials used for industrial purposes. The shippers believed that the cases were empties being returned to Amersham, which manufactures and distributes radiographic materials.
What workers who handled the crate on the dock, at the warehouse and in the truck did not know was that one of the supposedly empty cases contained a radioactive pellet.
They also were unaware that somewhere en route to Massachusetts the pellet had become dislodged from the side of the carrying case designed to shield the public from radiation.
A 150-page report released in May by the U.S. Nuclear Regulatory Commission concluded that the shipment of the pellet was inadvertent and that no one was exposed to doses of radiation large enough to significantly increase their risk of getting cancer. But it cautioned that the pellet "had the potential to cause high radiation exposure to members of the general public."
After tracking the crate's movements, investigators placed the blame on the South Korean shippers for allegedly failing to heed U.S. government safety rules by not labeling the crate and its contents as radioactive. There were no warning signs on the truck that took the cargo cross-country--through parts of Los Angeles, Orange and San Bernardino counties as well as the cities of Albuquerque, Oklahoma City, St. Louis, Baltimore and Philadelphia.
The U.S. Department of Transportation is continuing to look into the shipment and is "considering taking enforcement action" against those responsible in South Korea, said John O'Connell, an official in the department's office of hazardous materials. The shippers could face civil fines of up to $10,000 a day for each day the shipment was in transit.
In fact, the South Korean shipper, NDI Corp., believed the containers were empty, according to K.Y. Kim, the company's president. But he acknowledged that his firm failed to adequately check the carriers before packing them.
However, even if the crate and shipping papers were properly labeled, "nothing would have changed" in the way it was transported because no one knew the radioactive source had been dislodged from the carrying case's shielded portion, according to Willard Brown, who headed the Nuclear Regulatory Commission team that investigated the accident.
The failure to follow shipping regulations is "sort of a moot point," Brown said, because "what (the South Koreans) failed to do was test the units before they were shipped."
Brown said that between 1985 and 1989 there were at least nine other unmarked shipments from South Korea. But in those cases, he said, the radioactive source remained in the shielded half of the compartment.
The Amersham incident points out gaps in the government safety system devised to protect the public from potential accidents involving nuclear shipments.
The U.S. Department of Energy estimates that every year at least 2 million shipments of radioactive materials are transported across the nation in trucks, trains, planes and barges. Almost two-thirds of the shipments are for medical purposes, with the balance used in nuclear power plants, industry and research.
Although federal investigators minimize the risk associated with the Amersham incident, the Sandia National Laboratory in New Mexico says that between 1971 and 1989 there were 3,213 radioactive packages involved in transportation accidents. Forty-six of those accidents involved packages designed to withstand major wrecks without releasing their contents. None of the accidents have exposed the public to radiation.
However, people have been exposed to radiation released in accidents involving lower-level nuclear products carried in weaker kinds of packages, the lab reported. Most involved only small amounts of radioactive materials.