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Exposure of a worker in excess of the statutory dose limit

Date released
4 November 2022
Request number

202210036

Release of information under
Freedom of Information Act 2000 (FOIA)

Information requested

I am writing you with reference to the event at Sellafield Ltd. UK on 2022-05-25. It is stated that extensive investigation, including bioassay data analysis and a detailed review of working circumstances and facility state, concluded that the worker received an internal (effective) dose of 23.00 mSv in 2020 by inhalation of resuspended surface contamination of recently separated material. I have some queries related to this event and I hope you will have no objection in answering the queries. 

  • Which bio assay analysis was used for the estimation?
  • Which radioactive material was in identified in the bio assay analysis?
  • What was the activity in the sample?

Information released

I confirm that under s.1 of the FOIA, we hold some of the information relevant to your request. Please see below for a response to your questions.

  • Which bio assay analysis was used for the estimation?

I confirm that we do not hold this information. We are aware that a number of urine and faecal samples were taken by Sellafield Ltd but we are not aware of the analysis technique used on these by the Sellafield Ltd Approved Dosimetry Service. The assessment of the dose was carried out following the assessment procedures in the IDEAS guidelines. This assessment fits both urine and faecal data into one assessment. The IDEAS guidelines can be found in the following reference: Castellani, CM et al., IDEAS Guidelines (Version 2) for the Estimation of Committed Doses from Incorporation Monitoring Data, Eurados Report 2013-01, Braunschweig, March 2013.

  • Which radioactive material was in identified in the bio assay analysis?

I confirm that Plutonium (alpha) and Americium (alpha) were identified in the urine and faecal samples. However, we do not hold any information on the breakdown of the different isotopes within the sample.

  • What was the activity in the sample?

I confirm that we do not hold this information.

Further information

For more detailed information on the bio assay analysis we suggest contacting the Sellafield Ltd Approved Dosimetry Services at the following email address:

Exemptions applied

N/A

PIT (Public Interest Test) if applicable

N/A