Post Mayapuri radiation incident, all the stake-holders including regulators, woke up to a stark reality. It cannot be business as usual. The mistaken notion of a few academics about the concept of “half life” caused the first radiation death in India; it led to radiation injuries to a few persons. Radiation sources used in universities and research institutions are now under renewed attention.
There is some concern that universities may totally abandon the use of all radiation sources. If that happens, it will be unthinkable. The Department of Atomic Energy, its aided institutions and others conversant with safe use of radiation sources must come forward to re-establish the confidence that is shaken because of the Mayapuri incident.
We have a large pool of specialists who can help. They can assist the universities in preparing an inventory of sources and in drafting manuals containing the dos and don'ts in handling radiation sources. Aberrant behaviour of an institution must not discourage others.
Back to basics
The incident unwittingly highlighted the need to go back to basics. Helpful media coverage revealed the depth of ignorance of some of the participants. Even after the horrendous mistake, many do not know the concept of “half life”, “shielding effectiveness of lead aprons” etc
A chemistry professor in Delhi University claimed that this Co-60 source could have been active for 12 years more! He does not know that even after 12 more years (just over two more half lives), the source would have been hazardous with an activity of 4 to 5 Ci.
Gamma cell has inherently safe features. When the cell was in use those who went to the room where the gamma cell was stored used to wear lead aprons thinking that it will protect them. A lead apron typically has a thickness equivalent to 0.25 or 0, 5 mm of lead and offers virtually no protection against the gamma rays from Co-60.
A department in another university opted for a single personnel dose monitoring badge for a few students. Any student going to the source room carried it! This came to light during a survey.
The erstwhile Directorate of Radiation Protection (DRP) received a parcel which contained the personnel monitoring film badges and a depleted radioactive source. A professor wanted to “recharge” the source in one of the reactors at the then Atomic Energy Establishment Trombay. Completely blackened film due to radiation exposure from the source alerted the officials of DRP.
Once a physics professor received a radiation dose much higher than what he was normally receiving. On investigation, we found that he got exposed while preparing a routine experiment to find shielding ability of different materials. He inadvertently kept a highly active gamma source on the bench top unshielded while arranging the experiment.
Analytical x-ray units
Radiation sources such as analytical x-ray units used commonly in universities have caused accidental exposures much larger than those for any other radiation equipment we know of today.
The radiation exposure rate near the beam port ranges up to 400,000 R/min. A serious burn can occur from even a one to two second exposure to such a beam. A survey revealed that about one serious exposure (to hands or fingers of the individual involved) occurs per 100 machines in a year in the USA. Nearly one out of five who was exposed accidentally underwent amputation of the fingers with possible long term effects.
Modern machines are safe, if used as instructed. But researchers at times change the design, interfere with the interlocks, remove pieces of the system inadvertently or install accessories improperly.
The usual cause for serious radiation injury is from the insertion of the fingers into the
primary beam, leakage of primary beam photons due to inadvertent or accidental
removal of pieces of the system, or improper installation of accessories.
International Atomic Energy Agency (IAEA) once discussed the familiar scenario. A professor indents a source. A few students use it under his guidance. After he retires, the source remains unused. The–cradle-to-grave concept is seldom applied in such cases. No Indian scientist would have ever imagined that they will face such a situation. There must be dedicated training programmes for researchers. The current radiation safety training organized by BARC must be strengthened
[The author is Raja Ramanna Fellow in the Department of Atomic Energy. He can be contacted at firstname.lastname@example.org]