Environment Report 2018

Naturally Occurring Radioactive Materials (NORM) in Produced Water Radium and many other radionuclides occur naturally in seawater and have done so for millions of years. The UKCS rock strata contains radionuclides of the uranium and thorium decay series, some of which dissolve into the water in the reservoir. These materials do not have a significant impact on the marine environment or human health. Discharges of NORM are controlled through authorisations issued under the Radioactive Substances Act (RSA) 1993. A condition of these authorisations is to notifiy the relevant environment agency if the concentration of Ra-226 is greater than 0.1 becquerel per millilitre (Bq/ml). There has been an increase in total NORM activity (Pb-210, Ra-228, Ra-226) discharged to sea of 3 per cent compared with 2016. The amount of NORM discharged is dependent on the reservoir conditions and the volume of produced water discharged. The average Ra-226 concentration and the average total NORM concentration remain consistently and significantly below the 0.1 Bq/ml limit by two orders of magnitude.

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Figure 4: Breakdown of NORM Discharged in Produced Water

Pb-210 (MBq)

Ra-226 (MBq)

Ra-228 (MBq)

Ra-226 concentration (Bq/ml)

Total NORM concentration (Bq/ml)

0.007

800,000

700,000

0.006

600,000

0.005

500,000

0.004

400,000

0.003

300,000

Concentration (Bq/ml)

0.002

200,000

0.001

100,000

Total NORM Activity Discharged to Sea (MBq)

0

0

2009 2010 2011 2012 2013 2014 2015 2016 2017

Source: EEMS October 2018

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