What the U.S. team, led by Department of Energy (DOE) scientists, will find is that the number of people exposed to radiation has increased to 69. The increase from 49, the original number of people exposed, is due to an inadequate monitoring system, the Japanese government said Oct. 15.
All but 10 of the 69 are workers at the plant. According to a report submitted by Japan's Nuclear Safety Commission, the 20 new readings came from badges the workers wore to monitor radiation levels. Investigators did not check the badges until recently.
The accident happened because of a technique, not used in the United States and illegal in Japan, where uranium powder is dissolved in nitric acid during final stages of fuel element production. Company officials believe too much uranium was put into the acid, causing an uncontrolled atomic reaction and sending radiation spewing into the air. Three workers were hospitalized.
Workers were exposed to radiation levels 50 to 100 times higher than what is considered safe to receive over the course of a year, the report determined. Workers at the facility routinely violated safety procedures, were under pressure to get the job done quickly and had not received proper training.
In the days following the accident, the United States provided technical information concerning criticality accidents and radiation monitoring. The information included technical manuals used to respond to this type of accident and medical treatment procedures for workers exposed to radiation.
The three U.S. experts, with expertise in criticality, process chemistry and integrated safety management, will exchange information with the Japan Atomic Energy Institute and the Japan Nuclear Cycle Development Organization. They are not expected to go on site because of ongoing decontamination efforts.
The three are leader Frank McCoy, deputy manager of DOE's Savannah River Operations Office and an expert in the management of commercial and government nuclear facilities, with particular expertise in safety issues; Dr. Leroy Lewis, a chemist with DOE"s Idaho National Engineering and Environmental Laboratory and an expert in all phases of nuclear fuel reprocessing; and Dr. Thomas P. McLaughlin, group leader of the Criticality Safety Group at DOE's Los Alamos National Laboratory.
"These U.S. experts will be able to help the Japanese people and the international scientific community better understand why the accident happened. They will also analyze the procedures and processes used to respond to the incident," Energy Secretary Bill Richardson said. "It is our hope that, by working together to produce the most thorough analysis possible, we can help improve safety at nuclear facilities worldwide."
The Nuclear Energy Institute (NEI) is coordinating a U.S. industry review to examine causes of and responses to the accident. Although U.S. fuel fabrication and nuclear power plants have in place a series of safeguards that would prevent a criticality accident, the review is aimed at increasing knowledge of what happened in Japan.
"The benefits that society derives from nuclear technology ... are too great to allow there to be lingering questions about the events that transpired in Japan," said Marvin Fertel, NEI's senior vice president for nuclear infrastructure support and international programs.