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All lessons will be learned from the March cesium incident

All lessons will be learned from the March cesium incident

23 May 2016 16:10
Press release

A damaged radiation source located in the premises of a company that handles small quantities of radioactive waste contaminated the premises of the Radiation and Nuclear Safety Authority (STUK) in March. The incident resulted in significant decontamination measures, as some of the official operations of STUK are activities that require a perfectly clean laboratory and measurement environment.

The broken source was revealed by a chain of events that began when an elevated, albeit very small, cesium concentration was analysed from an air sampler on the roof of the premises. A person should breathe air similar to that in the observation continuously for 1600 years before exceeding the normal annual radiation dose of a Finn (3.2 mSv).  However, measurements were made to ensure that the incident did not have any health effects.

The Safety Investigation Authority decided to launch an investigation of the incident on 23 May.

The Safety Investigation Authority will investigate the cesium incident

”During the spring, our management team discussed the need for an independent assessment of the cesium incident, and we found that one would be very useful. Therefore, I contacted the Safety Investigation Authority (OTKES) and requested them to consider conducting an investigation,” says Petteri Tiippana, Director General of STUK.

OTKES makes decisions on commencing investigations independently. In addition to investigating accidents and hazardous situations, OTKES can consider conducting an investigation of other events under the Safety Investigation Act, for example when requested by an authority.

”We have assessed our operations in-house, but I believe that OTKES will help us to obtain more information that will help in developing the activities of the authorities as well as requirements and safety culture, emergency preparedness and communications. We want to act in the way we require others to act, i.e. openly and courageously, questioning and developing our operations,”  Tiippana continues.

Decontamination plan for the company’s premises is complete

The company has submitted a plan for decontaminating its premises to STUK. STUK aims to contribute to more detailed investigations being made on the failed cesium source to prevent similar incidents in the future. 

”We must learn all possible lessons from this and also proactively share them. We are developing the supervision of currently used and decommissioned radiation sources and will instruct operators to develop their handling and storage practices further,” says Eero Kettunen, Director of the Department of Radiation Practices Regulation.
 

For additional information, please contact

Kaisa Koskinen, Director, +358 9 759 88 322
Kaisa Raitio, Communications Manager, +358 9 759 88 795

Safety Investigation Authority: New investigations


Broken radiation source contaminated STUK’s premises

  • On Monday, 7 March 2016, STUK announced that it had detected elevated Cesium 137 concentrations.
  • The observation was made by an air sampler on the roof of STUK’s premises in Helsinki.
  • The sample from which the elevated concentrations were measured had been collected on 3–4 March
  • The detected cesium concentration was so low that a person should breathe the air continuously for 1600 years before exceeding the normal annual radiation dose of a Finn (3.2 mSv).
  • Tests made after the observation excluded the possibility of the radiation source originating from STUK’s laboratory
  • The samples of air samplers located elsewhere in Finland were analysed, and no elevated concentrations were observed
  • As a precautionary measure, measurements were also made in the environment of the premises, in Roihupelto, Helsinki, and the radiation situation was found to be normal
  • On Wednesday, 9 March, the radiation source was found to be in the premises of a company that processes small quantities of radioactive waste, located in the same property as STUK.
  • The source and the contaminated premises were isolated and decontamination measures were commenced
  • The garage was the most contaminated area in STUK’s premises
  • All surfaces must be decontaminated thoroughly in the premises, as some of the official operations of STUK are activities that require a perfectly clean laboratory and measurement environment.
  • However, measurements were made to ensure that the incident did not have any health effects.
  • The employee who handled the radiation source did not have abnormal cesium levels in the body
  • The elevated radiation concentrations were caused by a damaged level sensor decommissioned from UPM Kymmene’s Kaipola mill
  • STUK ensured that the premises of the Kaipola mill were not contaminated in cooperation with UPM, and the measurements did not indicate anything abnormal
  • Thousands of similar sources are used in Finland, and their shielding normally prevents damage to the source
  • The company has prepared a plan for decontaminating its premises
  • STUK premises have been decontaminated and operations have continued in the normal way after that

 

What is an air sampler?

  • Air samplers can detect very small changes in radiation
  • There are air samplers in eight locations in Finland: Helsinki, Imatra, Ivalo, Kajaani, Kotka, Kuopio, Rovaniemi and Sodankylä
  • The filters of the sampling stations are analysed weekly at STUK’s laboratory
  • If elevated concentrations are detected, they could indicate an emission from a nuclear facility, radiation source melted in a smelting plant, emission that has taken place in connection with the production of radioactive materials or a nuclear test.  
  • The results are published on the STUK website


Radiation is monitored 24/7

  • Real-time radiation situation is monitored with an outdoor radiation measurement network
  • 255 stations across Finland
  • The indicators are updated once every 10 minutes, and the results are also transmitted to the STUK website once an hour: Radiation today
  • If the station-specific alarm limit is exceeded, the emergency response centre and STUK are automatically notified.
  • There are international agreements on reporting radiation hazards and nuclear accidents, and information about a radiation hazard threatening Finland would be received even before the measurement network indicated the changed situation or shielding became necessary.

 

  • STUK’s operating principles include reporting changes in radiation observed by air samplers or outdoor radiation network, for example, openly and without delay

 

STUK - Radiation and Nuclear Safety Authority
Updated
24 May 2016 12:24
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