UK response plan and Radioactive Incident Monitoring Network (RIMNET) 3: briefing note
Source: environment.data.gov.uk (2024-01-03)

BEIS: Ambient gamma radiation dose rates across the UK. Data received from 96 fixed and mobile monitors measuring the ambient (background) gamma radiation dose rate across the UK on an hourly basis.
Background radiation continues to be the main component of observed levels of gamma radiation recorded at sites. The observed UK annual radiation dose rate ranges from around 0.5 mSv to 1.0 mSv with an average of less than 0.7mSv.
High readings

Future data now published under DESNZ
The higher readings, identified by red type in the ‘Max’ column of these files, are at a level which requires investigation. Each has been investigated and no specific reason found.
It is not unusual to have a small number of slightly elevated readings, often referred to as anomalies, which could be due to weather or power related factors, though the cause is often unknown. As no fault or reason was found, there is no justification for amending the readings on the database.

UK RESPONSE PLAN AND RADIOACTIVE INCIDENT MONITORING 
NETWORK (RIMNET) 3: BRIEFING NOTE 
1.
What is the UK Response Plan?
The UK Response Plan is the UK Government's national contingency plan for 
dealing with the effects on the UK of overseas nuclear accidents. It is a composite 
plan, designed to co-ordinate the actions of the various Government departments 
and expert agencies that would be involved in the response to such an accident. 
Operation of the Radioactive Incident Monitoring Network (RIMNET) system is one 
element of the Plan. 
2.
What is RIMNET?
RIMNET is the UK Government's national radiation monitoring and nuclear 
emergency response system set up following the Chernobyl accident as part of its 
arrangements for dealing with the effects on the UK of overseas nuclear accidents.  
3.
What is DECC's role as the lead Government department?
DECC’s role as the lead Government department for overseas nuclear accidents is 
to:  
-
co-ordinate the Government's response;
-
keep Minister’s and Parliament informed of that response;
-
provide information to the public and the media at the national level;
-
operate the RIMNET system.
4.
What is the Technical Coordination Centre (TCC)?
The TCC is the centre from which the Government's response to an overseas 
nuclear accident will be coordinated. It will be attended by representatives of the 
Government departments, agencies and other bodies engaged in the response.  
5.
What are Assessment Centres?
Assessment Centres are places where Government departments and other bodies 
carry out assessments of radiological monitoring data in their particular areas of 
responsibility. The results of these assessments will be passed to the TCC to guide 
the Government response to the accident.  
6.
What is the role of other Government departments?
Other Government departments will continue to discharge their normal statutory 
responsibilities throughout the response to the accident. They will provide 
assessments and advice in those areas to the TCC to guide the Government 
response.  
7.
What is the role of Health Protection Agency?
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HPA (formerly NRPB) advise Government departments on the interpretation of 
radiological monitoring data, in particular dose assessments. It will make 
measurements of its own and enter the results onto the RIMNET database. It will 
also be represented at the TCC.  
 
8. 
What is the role of the Met Office?  
 
Met Office will provide predictions of the movement of the radioactive cloud from an 
overseas nuclear accident, using meteorological data and advanced computer 
models run at its Exeter headquarters. It will also supply weather radar data to help 
identify areas of possible radioactivity washout. Met Office will also be represented at 
the TCC.  
 
9. 
What role will the UK nuclear industry play?  
 
The UK Nuclear Industry could supply radiation monitoring data to the RIMNET 
database in the event of an overseas nuclear accident. DECC also have access to 
the UK nuclear industry emergency response information system. 
 
10. 
Planning of RIMNET  
 
DECC is advised on the planning and operation of RIMNET by a national committee 
known as the Radioactive Incident Monitoring Coordinating Committee, or RIMCC. 
This committee consists of representatives from Government Departments, 
Devolved Administrations, the Health Protection Agency, the Met Office, local 
authority associations and the nuclear industry.  
 
11. 
Notification of overseas nuclear accidents  
 
DECC would expect to learn of an overseas nuclear accident via one of the official 
international early notification arrangements set up following Chernobyl. These 
arrangements are maintained by the International Atomic Energy Agency (IAEA) and 
the European Union (EU). The UK Government also has a number of bilateral early 
notification arrangements, including France, Belgium, Netherlands, Norway, Russia 
and Ireland. In practice information and an unofficial notification may also come via 
the media.  
 
12. 
Will RIMNET provide early warning of an overseas nuclear accident?  
 
No. RIMNET is not an early warning system; the fixed monitors record what is 
happening at the site at the time. Any formal warning will come via the International 
Atomic Energy Agency, European Commission or through bilateral notification 
arrangements. RIMNET is an independent monitoring system which provides an 
alert mechanism. It also provides access to forecasts of the areas of the UK likely to 
be affected by any overseas nuclear accident based upon Met Office data and 
models.  
 
13. 
Are there enough fixed monitors?  
 
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Yes. There are enough fixed monitors to detect a dispersed radioactive cloud of the 
kind that is likely to stem from an overseas nuclear accident by the time it reaches 
the UK. In practice monitoring by the UK nuclear industry and other approved 
suppliers would supplement the RIMNET fixed monitor data.  
 
14. 
What is the RIMNET Approved Data Supplier Scheme?  
 
The RIMNET Approved Data Supplier Scheme enables non-Government bodies to 
supply monitoring data to the RIMNET database. In return Approved Data Suppliers 
will receive, via electronic mail, Government alert messages, information and advice 
bulletins, and summaries of other data held on the RIMNET servers relevant to their 
local areas and fields of interest. Only organisations which can demonstrate ability to 
make radiological measurements to the necessary RIMNET standards will be 
approved. Standard national protocols will apply to the collection and supply of data.  
 
15. 
How will local authorities be kept informed?  
 
Arrangements have been negotiated with the local authority associations to provide 
regular information and advice bulletins to about 70 host local authorities via 
electronic mail. These local authorities are normally at the county level, and they will 
cascade the bulletins to other local authorities in their area.  
 
16. 
Will RIMNET be able to detect "hot spots"?  
 
RIMNET provides access to weather data which indicates where rain has or is or is 
likely to occur. This in turn indicates whether there could be high levels of 
radioactivity washout ie possible "hot spots". Mobile monitoring teams will be 
directed to areas of particular concern.  
 
17. 
Does the UK Response Plan allow for evacuation, shelter and 
distribution of iodate tablets to the UK population?  
 
No. The conclusions of a review following Chernobyl suggested that such measures 
will not be needed for overseas nuclear accidents.  
 
18. 
How will the public be kept informed?  
 
Information will be issued to the media and the public by the News Coordination 
Centre maintained by the Cabinet Office and supported by DECC Press Office. Once 
a notification has been received RIMNET can be used to brief the Press Office on 
the nature of the accident, the likely direction of movement of the radiation cloud and 
its potential impact on the UK. Thereafter, the UK environment will continue to be 
monitored using the UK Response Plan and RIMNET arrangements, and appropriate 
advice to the public compiled. Information will be made available in regular press 
releases and briefings, in electronic mail bulletins to official bodies, both within and 
outside Government so that it can be passed on to the public in their homes and 
workplaces.  
 
19. 
Why is RIMNET equipped with gamma rather than alpha detectors?  
 
Withdrawn

The most significant effects of overseas nuclear accidents on the UK will be through 
gaseous or vaporised gamma emitters. Alpha particles are associated with heavy 
metals which, under accident conditions are released as particulates. Unless 
extremely fine, these will be deposited close to the scene of the accident and not 
reach the UK.  
 
20. 
How reliable is the RIMNET system ?  
The RIMNET system has been designed to have no single point of failure. The main 
computers are duplicated, and allow for switchover in the event of failure. The 
system has its own protected power supplies. Extremely tight performance and 
response time criteria are written into the system maintenance contract.  
 
21. 
How safe are overseas nuclear reactors?  
 
Operation of nuclear reactors in Western Europe is subject to strict design, 
operational and regulatory standards laid down by the European Union and the 
International Atomic Energy Agency. The operation of nuclear installations in Eastern 
Europe is also subject to such standards since Chernobyl. A lot of western expertise 
in these areas has been passed on through aid arrangements. This means that the 
chances of accidents should be diminishing all the time. Nevertheless the UK 
Government remains alert to the possibilities of such occurrences, hence the UK 
Response Plan and RIMNET provisions.  
 
22. 
How will UK Response Plan and RIMNET arrangements be tested?  
 
RIMNET participates in regular exercises and tests of nuclear emergency response 
arrangements. On average, 4-5 civil and 4-5 military exercises per year, of which at 
least 1 is a national-level fully integrated exercise involving all bodies. International 
exercises tend to be held on an 18 month cycle to replicate summer and winter 
conditions because meteorological effects on deposition vary.  
 
23. 
Will the RIMNET system be used for routine radiological monitoring 
data?  
 
Yes. A database of routine monitoring data supplied by Approved Data Suppliers is 
maintained to enable comparison of normal results with data collected during an 
incident situation. In addition, radiological monitoring data is routinely exchanged 
with Europe under EURDEP: the European Union Radiological Data Exchange 
Platform.  
 
24. 
Incidents close to or within the UK  
 
RIMNET was designed to support the response to accidents within the UK for which 
there are separate and well-tested site-specific arrangements. The use of RIMNET, 
modelling and communications facilities in domestic civil, military and CBRN 
emergency planning has become a regular feature of exercises. The UK should 
receive early notification of any accidents within Western Europe through the EU and 
IAEA early notification arrangements, and would track and monitor any effects on the 
UK using RIMNET.  
 
Withdrawn

25. 
Local information 
 
The RIMNET data, both from fixed monitor and supplementary data, input will 
provide the basis for issuing local information.  
 
26. 
Staffing  
 
DECC maintains, through the Met. Office, a RIMNET operations team consisting of 
five staff. They are trained in overseas nuclear accident response procedures and 
use of the RIMNET system. An on-call rota ensures that staff are contactable at any 
time, 24hours/365 days a year. The RIMNET staff have access to the additional 
radiological expertise of other agencies. There are well-rehearsed procedures for 
calling in other DECC and other agency staff as necessary to deal with the response 
to an overseas, or indeed any, nuclear accident.  
 
27. 
Quality Assurance of RIMNET data  
 
The RIMNET fixed gamma dose rate monitors are subject to annual calibration, and 
interim checks. Approval of supplementary data suppliers will be based on 
appropriate quality assurance schemes coupled thereafter with data supply 
performance. These assurance schemes include NAMAS accreditation by the 
National Physical Laboratory, accreditation under the local authorities LARRMACC 
scheme and registration as HSE Approved Dosimetry Services.  
 
Note: NAMAS stands for National Measurement Accreditation Service. LARRMACC 
stands for Local Authorities Radiation and Radioactivity Monitoring, Advice and 
Collection Centre.  
 
28. 
Why is DECC the lead department for UK nuclear accidents?  
 
Lead Department responsibilities are allocated on the basis of the nature of the 
accident and the normal day-to-day business of individual Government departments. 
In the case of a UK nuclear accident, the primary activity is to bring the accident 
under control and thus DECC as sponsor department for the nuclear industry, 
assumes lead responsibility.  
 
29. 
Use of RIMNET for response to UK nuclear accidents  
While the UK Response Plan provides the response framework for a nuclear 
accident abroad there are separate and well-tested plans for dealing with nuclear 
accidents within the UK. The RIMNET design makes provision for other lead 
departments to use the system to assist with the response to UK nuclear 
emergencies.  
 
30. 
Will RIMNET detect accidents in the UK?  
 
The RIMNET monitors will detect increases in gamma dose radiation levels at the 
fixed sites irrespective of their cause. However, we would expect any increases 
due to accidents at UK nuclear sites to be notified by the site operator and 
detected first by site perimeter monitoring systems. RIMNET monitor sites were 
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deliberately positioned away from nuclear sites to avoid false alarms arising from 
authorised discharges, and duplication of monitoring resources.  
 
31. 
Would RIMNET be able to deal with the effects of a nuclear strike on the 
UK?  
 
It may, depending on location and severity of the strike, but RIMNET has not 
been designed for this purpose. RIMNET would however, be used to assist the 
MoD response to such an occurrence.  
 
32. 
Will RIMNET be used to deal with other types of national emergencies?  
 
The RIMNET system has been designed specifically to deal with overseas and 
other nuclear incidents. However, its use for response to other types of 
emergency, eg, widespread flooding or storm damage, whilst not being ruled out, 
will be contemplated only where it clearly does not compromise this primary 
system function, ie, nuclear emergency response. 
Withdrawn