Contaminated metals in France and Sweden
Buttons produced at a factory in France for elevator manufacturer Otis have been found to be radioactive, as have metal components imported into Sweden. The source of the radiation has been traced back to a foundry in India.
An earlier version of this story incorrectly stated that the maximum regulatory dose rate for the public and nuclear industry workers is 1 mSv per hour. In fact, the maximum dose in France is 1mSv per year for the public and 20 mSv per year for nuclear workers.
Buttons produced at a factory in France for elevator manufacturer Otis have been found to be radioactive as have metal components imported into Sweden. The source of the radiation has been traced back to a foundry in India.
The manufacturer of the buttons, Mafelec, was alerted by US customer Otis of the presence of radiation in a consignment of buttons it had received. Mafelec informed the French Nuclear Safety Authority (Autorité De Sûreté Nucléaire, ASN) on 7 October.
The ASN took radiation measurements at Mafelec's plant in Chimilin in the Isère region of France. Abnormal levels of some 0.02 mSv per hour were discovered near several packages of metal discs which form the base of the lift buttons. In addition, the ASN found a dose of 0.05 mSv per hour at one of the workstations at the Chimilin plant. The regulatory maximum dose in France for the public is 1 mSv per year, while the maximum for nuclear workers is 20 mSv per year.
The ASN initially gave the incident a provisional classification of Level 1 on the International Nuclear Event Scale (INES). However, this was later changed to Level 2 when it was found that more than ten Mafelec employees had received doses exceeding the maximum regulatory level.
The ASN believes that the source of the radiation was likely to be cobalt-60 in the metal discs supplied from India. An inspection by the ASN on 8 October found that consignments of contaminated discs began to be delivered to Mafelec on 21 August. The ASN also determined that a total of some 30 Mafelec employees had been exposed to the radiation, of which about 20 had been exposed to doses ranging from 1 mSv to about 3 mSv.
Cobalt-60 is a corrosion product from nuclear reactor vessels and is mainly used in certain medical diagnosis and treatment equipment.
An investigation by the ASN in collaboration with the Directorate of Civil Aviation found that a consignment of contaminated lift buttons was sent in September from Roissy airport in France to the USA. On its arrival to the USA, a radiation detector indicated that two of the packages were contaminated. Although the two packages were then placed in a controlled area, the authorities do not appear to have been informed.
The ASN has informed the prosecutor of several offences committed by Mafelec, including some under the Public Health Act.
Meanwhile, Swedish officials have discovered traces of radioactivity on steel parts also imported from India. The Swedish Radiation Safety Authority (SSM) said that the levels of cobalt-60 in the steel parts were considered harmless and the components were not recalled.
SSM spokesman Mattias Sköld told the AFP news agency, "Dutch customs discovered that a shipment of industrial flanges from India to Sweden showed traces of cobalt-60." That led to the discovery that a similar shipment had been sent several weeks earlier from India and delivered to three undisclosed companies in the oil and heating sector at four sites in Sweden.
Sköld added, "Inspections were carried out and it was found that the level found in these products was very low and wasn't dangerous." He noted that SSM had contacted ASN over the Swedish discovery.
India's Atomic Energy Regulatory Board (AERB), which had been contacted by the ASN, said that the contamination had been traced back to the Vipras Castings foundry. Satya Pal Agarwal, head of AERB's radiological safety division, told AFP that the components used by Mafelec were supplied by two Indian companies - Bunts and Laxmi Electronics - which purchase inputs from SKM Steels, which in turn worked with the foundry.
Agarwal said that the AERB was still investigating the source of the contaminated scrap metal that had been melted down to produce the steel used in the parts. One possible source of cobalt-60 could be from scrapped hospital equipment used for radiotherapy treatment, which became mixed with other metals. Recycling facilities routinely check shipments of metals for radiation before melting them down but in this case, the practise appears to have failed.
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