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Government of

Information and public services for the Island of Jersey

L'înformâtion et les sèrvices publyis pouor I'Île dé Jèrri


​​Measuring radioactivity

The UK Health Security Agency, together with Natural Environment in Jersey, measure the amount of radioactivity in:

  • seawater
  • shellfish
  • seaweed

The sampling of various seaweeds, seawater and shellfish is now carried out by the Water and Air team, part of Natural Environment, based at Howard Davis Farm, Trinity JE3 5JP.

Previously Environmental Health in Jersey and The Centre for Environment Fisheries and Aquaculture Science(CEFAS) would sample and analyse:

  • milk
  • strawberries
  • various wet fish
  • sediment

Centre for Environment, Fisheries and Aquaculture Science

Nuclear testing

In the past, radioactivity has been detected as a result of nuclear weapons testing and the nuclear reactor accident at Chernobyl in the Ukraine in 1986. The programme can also detect other sources of significant widespread contamination in the environment.

The accident at the Fukushima Dai-ichi nuclear power station in Japan in March 2011 resulted in significant quantities of radioactivity being released into the air and sea. European Commission (EC) controls on imported food and animal feed products from Japan continued in 2020.

Food imported into the UK may contain radioactive contamination from the 1986 Chernobyl accident and other known or unknown sources. A monitoring system is in place to detect radioactivity in consignments. In 2020, no significant radioactivity was detected at entry points and there was no need to introduce food safety controls on any consignments.

Radioactive readings declined

Since the beginning of the 1990s the levels of man-made radioactivity in the general environment have fallen markedly and in many cases are now almost undetectable. The results in recent years continue to show a downward trend. No sources of radioactivity other than weapons testing and the Chernobyl accident were detected.

The UK Health Security Agency has published estimates of exposures to the UK population from naturally occurring and man-made sources of radioactivity. Most recent values show that naturally occurring sources, particularly radon gas, accounted for around 84% of the exposure from all sources of radioactivity. 


Man-made radioactivity in the environment, from the nuclear industry and from past testing of nuclear weapons, accounted for less than 0.2% of the exposure to the UK population. 

Marine testing

Marine samples are gathered from Jersey, the other Channel Islands and France and analysed by CEFAS in the UK. This testing allows surveillance of the effects of liquid disposals from the French reprocessing plant at Cap de la Hague and the nuclear power station at Flamanville.

The programme also serves to monitor the potential effects of historic disposal of solid waste at Hurd Deep. Hurd Deep is a deep underwater valley north west of the Channel Islands.

​Marine radioactivity in the Channel Islands 1990-2009


Annual sampling is carried out for:

  • sea water, this restarted in 2022 as contaminated water from the tsunami damaged Fukushima Dai-ichi nuclear power station may be released into the sea in 2023
  • oysters
  • lobster
  • edible crab
  • spider crab

Bi-annual sampling is carried out for:

  • Fucus celanides (Horned wrack seaweed) from Plemont

Quarterly sampling is carried out for:

  • Fucus vesicilousus seaweed
  • Ascophyllum nodosum seaweed from Rozel harbour


Results show that concentrations of radioactivity in fish and shellfish are low and some are lower than previous years. No evidence of radioactivity from the Hurd Deep site have been found. The latest report no 28 Radioactivity in the Environment and Food is now available and further information can be found at:

Radioactivity in Food and the Envir​onment (RIFE) reports on GOV.UK

Radioactive Incident Monitoring Network (RIMNET)

The Radioactive Incident Monitoring Network (RIMNET) is a network of 91 monitoring stations,  sited around the United Kingdom, which records and analyses the level of radioactivity across the United Kingdom and Channel Islands. A reading is taken from each station every hour and an alert triggered if radiation levels for specific isotopes rise significantly above normal background radiation levels at one or more stations.

The Jersey monitoring station is sited at the airport and maintained by Jerseys Meteorological Department part of Infrastructure Housing and Environment (IHE).

It's an early warning station if a cloud of radioactive material were to be blown over Jersey from Cape de la Hague or Flammaville or an incident elsewhere.  

The Jersey monitoring station also links in with the Emergency Planning function within the Government of Jersey.

Major emergencies and how to respond

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