Air monitoring in the UK following the Fukushima nuclear power plant incident in Japan

Transcription

1 Air monitoring in the UK following the Fukushima nuclear power plant incident in Japan Provision of assurance to members of the public Joanne Brown, Derek Hammond 16 th November 2011 Centre for Radiation, Chemical and Environmental Hazards

2 Contamination reaching the UK Incident at Fukushima occurred: 11 th March 2011 Detection in the UK via routine air monitoring: filters removed on 23 rd - 25 th March 2011 by HPA at Glasgow and Chilton (Oxfordshire) showed positive results for iodine-131

3 Air monitoring in response to incident Increased frequency to weekly sampling from beginning of April until end of June Very high volume air sampler run at CRCE Chilton daily from 28 th March to 15 th April

4 Routine surveillance air monitoring in the UK Routine surveillance air monitoring programmes in the UK: HPA, EA and SEPA Number of locations across the UK Fortnightly or monthly air filters Air monitoring reported by EA and SEPA as part of UK s EURATOM monitoring arrangements HPA report annually (CRCE report)

5 Public assurance HPA, EA and SEPA produced joint press statements on HPA web site: reducing from weekly fortnightly monthly until 14 th July Format agreed for presenting measurements to public Monitoring data agreed with scientists Public health messages led by HPA press office and agreed with other press offices.

6 Key messages Monitoring equipment is extremely sensitive and can pick up trace levels well below those that would pose any risk to human health Levels detected posed no risk to public health in the UK resulting from the release of radioactive material at the Fukushima facility. Levels measured were similar across the whole of the UK and consistent with levels found in other European countries

7 Weekly Measurements in air collected across the UK

8 Daily Measurements in air collected at CRCE Chilton 1200 Activity concentration in air 1000 µ Bq/m I-131 Cs /03 29/03 31/03 02/04 04/04 06/04 08/04 10/04 12/04 14/04 16/04

9 Other environmental sampling Measurements were taken in surface waters, rain, grass, soil and milk The vast majority of samples did not show the presence of detectable levels of iodine-131 or radioactive caesium from Fukushima Trace levels were measured in a few rainwater samples collected around the end of March. Levels of radioactive strontium and isotopes of plutonium were not above background levels measured normally in the UK

10 Ongoing monitoring Air monitoring frequency returned to normal in July HPA continues to check air filters for any sign of releases of radionuclides that could be attributable to Fukushima (Oxon, Jersey, Glasgow and Cumbria) Measurement results will be reported as part of the normal annual reporting by HPA, EA and SEPA An HPA-CRCE report will be produced containing all the HPA, EA and SEPA monitoring data related to the incident for the public record

11 What about gaseous iodine-131? Total iodine concentrations needed for dose estimates Chernobyl reliance on estimates and very few measurements Fukushima more measurements made across Europe HPA has decided to increase measurement capability to include gaseous iodine

12 Iodine-131 gaseous / particulate ratios during Fukushima Masson et al Gaseous 131 I / Total 131 I (%) Mean value Standard Deviation Total 131 I (mbq m -3 )

13 Increased measurement capability at HPA Cartridges containing activated carbon. Need 2 for measuring trapping efficiency Modifying existing air monitoring stations with activated carbon filter

14 Trapping efficiency for gaseous iodine-131 A 1 is activity in the first layer A 2 is activity in the second layer Y = yield

15 Gaseous Iodine sampling Training required for operators especially off site Ready supply of activated charcoal needed Reduced flow rate slightly higher limits of detection for aerosol/particulate 3 counts per sample 1 normal filter for particulates 2 charcoal filters for gaseous iodine

16 Acknowledgments John Titley, Environment Agency Paul Dale, Scottish Environment Protection Agency Centre for Radiation, Chemical and Environmental Hazards