Following reports in the media on Monday, officials of the Kakrapar atomic power station (KAPS) confirmed on Monday that four contract workers were exposed to nuclear radiation in the plant on May 30, 2011 due to human error of the control room staff. However, they said that the radiation was of a very minor level and that it had no effect on the health of the workers.
KAPS is situated at 75 km from Surat and about 12 km from Vyara which is the main city of Tapi district. It produces 440 MW from two units of 220 MW each which went critical in 1993 and 1995. Two more units of 700 MW each are being built and the work will be completed by 2015.
"Yes, the incident happened due to human error but the workers were not affected as the dose and quantity was very small," said P K Dutta, station director of KAPS. "All four were examined in our hospital to check for any radiation affect on their bodies. But, it was found that the radiation they were exposed to was only up to 90,000 million rays or 90 mSv (milli Sieverts). They were sent home as they within our radiation limits," he added.
"A radiation of 90 mSv does not cause any harm. If we get our whole body CT scanned, we would be exposed to a nuclear radiation of 60 mSv,'' said Dutta.
The doses of radiation which are safe and as prescribed by Atomic Energy Regulatory Board say that dose due to natural background radiation should not be more than 2.40 mSv. The limit for contract worker getting exposed should be15mSv and for employee the limit is 20 mSv. A person may suffer from nausea and vomiting if the he exposed to 2000 mSv or and in extreme cases suffer from acute radiation syndrome where in exposed to 5000 mSv.
The four daily-wage labourers were exposed to radiation when they were cleaning and painting a tunnel called the Spent Fuel Transfer Duct (SFTD). The control room released a pair of spent fuel bundles in the duct while the labourers were in it. According to Dutta, "The workers came out when realized that something was amiss as their thermo luminiscence detectors started glowing.''
Dutta said that a team of the Atomic Energy Regulatory Board visited KAPS on June 1 to inquire about the accident and make an inspection. However, the matter became public knowledge only when the four workers petitioned the Tapi district collector last week, saying that they wanted permanent jobs as compensation for suffering nuclear radiation. The collector sought an explanation from KAPS.
A doctor from KAPS said that a human being exposed to high nuclear radiation develops red spots on the entire body almost immediately. The victim also suffers from nausea and vomiting at regular intervals and may even suffer from genetic problems. "However none of these signs is visible on any of the affected workers and they are all safe,'' he said.
Dutta said all the four affected labourers worked in the nuclear plant for at least 20 days each in the months of June and July 2011, i.e. in the two months after the accident. "The two members of the staff responsible for the error have been put back into training and relieved of their duties of control room," he said.
The affected workers hail from Kalavyara village and their names are Jaysingh Chaudhary, Bachu Chaudhary, Dinesh Chaudhary and Dilesh Chaudhary. According to the KAPS report, they suffered radiation effects of 90.72 MSD, 66.12 MSD, 58.70 MSD and 23.23 MSD, respectively.
Officials in the Tapi district collector's office said, "The KAPS director has submitted the medical reports of all the four affected workers. The report is given by their in-house hospital doctor, G N Parmar.''
Tapi district collector RJ Patel said, "We had also sent our team to the village where the workers live and found them normal."
