Environment Report 2017

ENVIRONMENT REPORT 2017

Naturally Occurring Radioactive Materials 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 and some of these dissolve into the water in the reservoir. These do not have a significant impact on the marine environment or human health. Permits for offshore reinjection or discharge of produced water are approved on the condition that the operator notifies the relevant environment agency if the concentration of Ra-226 is greater than 0.1 becquerel per millilitre (Bq/ml). Discharges of NORM are controlled through permits issued under the Radioactive Substances Act (RSA) 1993. There is an increase in NORM discharged to sea of almost 50 per cent since 2014. The amount of NORM discharged is dependent on the reservoir conditions and the volume of produced water discharged. Despite this rise, the average Ra-226 concentration and the average total NORM concentration remain consistently and significantly below the 0.1 Bq/ml limit.

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

)qBM( aeS ot degrahcsiD ytivitcA MRON latoT

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

0

0

2009 2010 2011 2012 2013 2014 2015 2016

Source: EEMS July 2017

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