This story was updated on 27 April.
A New Delhi scrap dealer has died after suffering very serious exposure to radiation caused by handling a cobalt-60 source. Six pieces of the dangerous material were eventually recovered.
Radiation protection experts from the Department of Atomic Energy and the Atomic Energy Regulatory Board swooped on shops in the Mayapuri area of New Delhi on the evening of 8 April, one day after Rajender Prasad presented himself with radiation-induced symptoms. Prasad died from multiple organ failure on 26 April and six others remain in hospital, one in a critical condition, according to a Times of India report.
Produced in nuclear reactors, cobalt-60 is an energetic gamma emitter that is used for the sterilization of medical equipment, external irradiation in cancer treatment (teletherapy), industrial radiography and to measure density or thickness.
Normally sources such as these are kept under strict regulatory control. When these controls fail, they are termed 'orphan sources'.
Officials located the radiation source in Prasad's shop, as well as elevated radiation levels in two other shops in the immediate area. These three sources were immediately covered with metal sheets to reduce radiation levels and recovered to shielded containers on the morning of 9 April when the area was declared safe.
A follow-up survey brought to light two more sources in another shop 500 metres away, and finally one more patient came forward and another radiation source was recovered from him.
The entire market area was then surveyed and, "as no elevated radiation levels were found in all the areas surveyed, there is good confidence that there are no additional high radiation sources remaining in the area," said the AERB.
A total of eight patients have been reported from various New Delhi hospitals, the worst affected being Prasad who suffered exposure to 3.7 Sv. The exposures of the others ranged from between that level and 0.4 Sv. The severity of the exposure and the involvement of members of the public have contributed to the event being categorised at Level 4 on the International Nuclear Event Scale - an 'accident with local consequences'.
The origin of the cobalt-60 has not been confirmed, but facilities and that use it are required to be individually licensed and authorised by the AERB, which noted that "replacement of cobalt-60 needs AERB consent, which is granted on the basis that the used cobalt-60 is returned safely to its original supplier."
Researched and written
by World Nuclear News