Travails from cobalt-60 contaminated steel

THE HINDU

Date:13/11/2008 URL: http://www.thehindu.com/thehindu/seta/2008/11/13/stories/2008111350171700.htm Back Sci Tech

Travails from cobalt-60 contaminated steel

Contamination of steel is occurring in many countries

On October 22, AFP reported that some French factory workers were exposed to excessive levels of radiation, as they handled lift buttons made using unsafe material contaminated with cobalt-60 from India.

The French Nuclear Safety Authority estimated that 20 out of the 30 workers were exposed to doses ranging from one to three millisievert. The annual dose limit for non-radiation workers is one millisievert, the same as that for the members of the publ ic.

France’s Institute of Radioprotection rightly assured that the health risk to workers is low.
Nuclear event ratings

The French Nuclear Safety Authority rated the incident at Level 2 in the International Nuclear Event Scale (INES) of the International Atomic Energy Agency (IAEA). INES rates nuclear events on a scale of 0 (incident with no safety risk) to 7 (major accident). Events at Levels 1-3 are called “incidents”; Events from 4-7 are termed as “accidents”.

Steel items imported from India to Sweden have also been reported to show faint traces of radioactivity.

The Swedish Radiation Safety Authority considered the levels of cobalt-60 harmless and the components had not been recalled.

Scientists from the Atomic Energy Regulatory Board are investigating the incident.

A few contamination incidents occurred earlier. In 2004, low levels of radioactivity were detected in some of the steel door handles made by another Indian firm.

In this instance, the investigation has shown that it is likely that the manufacturer made door handles out of steel produced in a foundry where imported or domestic metal scrap containing cobalt-60 has been used.

Considering this as a wake up call AERB initiated several preventive measures. AERB has prepared an inventory of all radioactive sources in the country. The inventory is updated periodically.
AERB requirements

AERB allows anyone to handle sources only after ensuring that he/she is adequately trained. AERB requires that the licensees secure the sources adequately in their locations. The probability of an indigenous radioactive source getting into scrap is very low.

AERB officials held meetings with steel manufacturers, All India Induction Furnaces Association, and Engineering Export Promotion Council.

The Board had a series of five workshops with companies carrying out industrial gamma radiography in the country.

The Board advised steel foundry and mill owners to regularly check the scrap for radioactivity by using radiation detection instruments.

Suitable radiation detection instruments are available indigenously or can be imported. Obviously, some companies did not implement AERB’s advice.

Contamination of steel is occurring in many countries. As it happened in U.S.,those Indian companies which suffered are keen to check the scrap with radiation detection instruments.
Slow progress

There were plans to set up radiation monitors at shipping ports through which bulk of the imported scrap metals enter the country. Though the discussions on this programme got started several years ago, the progress has been very slow.

The programme requires coordination from several Central ministries.

Many DAE Installations have been successfully maintaining such radiation monitors at their entry points for the past several decades.

K.S. PARTHASARATHY

Former Secretary, AERB

( ksparth@yahoo.co.uk )