Traces of plutonium in workers’ urine
Doctors say extremely small quantities of radioactive substances have been detected in the urine of 5 workers who were accidentally exposed to the materials early this month at a research facility north of Tokyo.
The incident took place on June 6th at a facility of the Japan Atomic Energy Agency in Oarai Town, Ibaraki Prefecture. The workers were inspecting a nuclear fuel container when a bag inside suddenly burst, expelling radioactive powder.
The agency initially said as much as 22,000 becquerels of plutonium-239 were detected in the lungs of one of the workers. But they were discharged from hospital by Tuesday of last week after repeated examinations at the National Institute of Radiological Sciences detected no plutonium in their lungs.
On Monday, the institute said checks of the 5 workers’ urine later revealed extremely small amounts of plutonium and other radioactive materials.
It says the workers have so far suffered no damage to their health, but that they have reentered hospital to take medicines that will purge the plutonium from their bodies. They will take the drug for 5 days, after which doctors will decide if further medication is necessary.
An official related to the institute says the radioactive materials in the workers’ bodies are at levels that will not immediately affect their health.
Meanwhile, the Japan Atomic Energy Agency, which employs the 5 workers, on Monday submitted to the country’s nuclear regulator an interim report on how the accident unfolded.
The agency’s president, Toshio Kodama, told reporters that he apologizes to the public for the incident. Kodama added that his organization may have problems sensing and foreseeing risks.
Kodama said the agency has to work on organizational issues, including worker awareness.
The agency says it plans to conduct a detailed investigation into the cause of the accident. It says it will consider measures to prevent recurrences and report to the regulator.
Tokyo, June 19 (Jiji Press)–Trace amounts of plutonium have been detected in the urine of all five workers exposed to radioactive materials at a nuclear research facility in eastern Japan earlier this month, a radiological research center treating them said Monday.
The radioactive substances detected in the urine were plutonium-239, plutonium-238 and americium-241, the National Institute of Radiological Sciences, or NIRS, said.
The results showed that the workers at the Japan Atomic Energy Agency’s Oarai Research and Development Center in Ibaraki Prefecture, northeast of Tokyo, suffered internal radiation exposure, the NIRS said.
The NIRS plans to continue examining the five workers for about a month to estimate levels of exposure.
The exposure is unlikely to reach levels that cause symptoms, said Makoto Akashi, a senior official at the National Institutes for Quantum and Radiological Science and Technology, which oversees the NIRS.
Plutonium found in urine of 5 workers in Ibaraki accident
Minute amounts of plutonium have been detected in the urine samples of all five workers who were accidentally exposed to radioactive plutonium at Japan Atomic Energy Agency (JAEA)’s Oarai Research and Development Center in Oarai, Ibaraki Prefecture, on June 6.
The test results were announced June 19 at a news conference by the National Institute of Radiological Sciences (NIRS) within National Institutes for Quantum and Radiological Science and Technology (QST).
The revelation marks the latest twist in the changing assessment of severity of the health risks in the accident. Initially JAEA announced on June 7 that one of the five workers had suffered an internal exposure of 22,000 bequerels during an inspection at the nuclear energy research center. On June 9, JAEA said no plutonium was detected in any of the five workers’ lungs in further testing by NIRS.
Makoto Akashi, an executive of QST, said at the news conference the latest finding confirmed that the workers did “suffer an internal exposure.”
While maintaining the level of exposure the five workers experienced “would not have immediate effect on their health for a few months,” Akashi said their internal exposure levels are “relatively high for cases occurring in Japan as far as I know.”
He also added that long-term observation may be necessary depending on the level of internal exposure.
JAEA’s initial “internal exposure of 22,000 bequerels” assessment was hastily done on the night of the accident on June 6. The five workers were examined using a dosimeter that can detect small traces of X-rays emitted by plutonium particles inhaled into the lungs.
However, the next day, NIRS staff discovered that four of the workers did not have all the plutonium on their bodies completely removed. After thorough decontamination efforts, they were retested for plutonium in the lungs, which was “not detected.”
It is believed the initial assessment came back with a high reading, as the dosimeter also picked up the radiation from the plutonium residue on their bodies.
In urine testing, NIRS said it can detect smaller amounts of plutonium as the measurement time is much longer, while the smallest radiation doses the dosimeter for lungs can detect is between 5,000 and 10,000 bequerels.
The latest test result suggests the possibility that some plutonium particles inhaled into the workers’ lungs have been absorbed into the bloodstream, then discharged into the urine.
The five workers had been discharged and are in stable condition, but were readmitted to the institution for further treatment on June 18. They started receiving medication via intravenous drip injections to speed the excretion of radioactive substances in their bodies from June 19, according to NIRS.
It is the second time they have received this medication. NIRS confirmed the treatment’s effectiveness as the amount of plutonium in their urine increased after the first round of injections compared to the amount found prior to receiving the drug.