Learning for nuclear emergency planning from COVID-19?

The model of the UK response to a nuclear emergency that results, or may result, in a plume of radioactive material spreading across populated areas of the countryside is to get the local responders, notably the local authority, emergency services and health services, in one place to discuss, decide, coordinate and respond.

Within the model is a unit called the Science and Technical Advise Cell (STAC) with the mission “to ensure timely coordinated scientific and technical advice during the response to an emergency”. We were told that “The STAC should bring together technical experts from those agencies involved in the response and who may provide scientific and technical advice to the Gold Commander. The purpose of the cell would be to ensure that, as far as possible, scientific or technical debate was contained within the cell so that the SCG (and others involved in the response) received the best possible advice based on the available information in a timely, coordinated and understandable way.”

Implicit in this process is the assumption that in any event there is an objective truth and that if scientists chat about it for a while they will determine and understand that truth and be able to explain it to the decision makers who have been too busy on other aspects of the response to explore the science for themselves. The decision makers will be jolly grateful to the STAC and, armed with the scientific consensus, will go on to make the right decisions. They might even say time after time that they are being driven by the science.

In this ideal world, these decisions will be reported to the public and to the media, will be implemented and the crisis will be bought to a close. Also in this ideal world the decisions turn out to be the “right” decisions and the only decisions that could be considered to be “right”, all other options, explored and unexplored, being “wrong”.

One thing we have definitely seen with the coverage of Covid-19 is that the media will not just forward your advice to the public as you might hope. Instead they will turn out an army of interpreters who, fearful that Mrs Miggins and her neighbours will not understand that those in a defined area are being asked to shelter and those outside the area are not, will explain at length what they think “shelter” means and why it has been recommended. They will then find a talking head to explain it again and then another to say that the previous interpretation was wrong and that the public should be being advised to do something else entirely. They will summarise by saying that there is a lack of clarity in what the advice is and who it applies to before cutting to a member of the public who will confirm, in response to a loaded question, that they don’t understand the advice and that they are very worried.

Returning to the decision making, the major issue is that the science does not give all the answers. We may be able to estimate radiation doses to the public, with and without protective actions, but these will be educated guesses rather than accurate. The amount of dose saved (benefit) that makes a protective action (with a cost) worthwhile is debatable and probably different for different people in different situations. The decision to interrupt the lives of people and ask them to stay in their homes knocking back stable iodine tablets is therefore a judgement call not the outcome of a neat equation. This is particularly true when you realise that the estimates of future doses are horribly dependent on assumptions made about what is happening, and what is going to happen, in the bowels of a damaged nuclear facility, what the weather will be when the activity gets out and where the members of the public will be and what they will be doing. Again the media will bring out an army of “experts” to discuss the technology, the science and the decision making process and will argue that the science is debatable, the process flawed and that any of the decisions made are dubious.

Maybe what should happen is that advisors advise and decision makers decide. The spokesperson issuing the advice should state that the decisions have been taken by the Strategic Coordination Group who took into account scientific advice, advice about the incident and how it could develop and the concerns of and for the people affected.

The media should be asked to transmit the advice as given and to resist reheating and reinterpreting it.

That will work.

What are the lessons for the nuclear industry from Covid-19? How do we ensure that our protective action decision making process is robust, transparent, unambiguous and trusted to ensure a high level of public compliance and optimum dose reduction?

REPPIR 2019 Transition

The REPPIR 2019 regulations come into force on 22nd May 2019. http://www.legislation.gov.uk/uksi/2019/703/contents/made

REPPIR 2019 cover

Any person who had a duty under REPPIR 2001 can continue to use these older regulations until May 2020 when they must be fully compliant with the newer regulations.

So what has to happen within the next 14 or so months?

Regulation 3 (application) is fairly straight forward. The operator must compare their holdings of radioactive material with schedules to determine if the regulations apply to them.

A written “hazard evaluation” is required for sites that pass the regulation 3 test (regulation 4). Preparing this from scratch could be onerous for a complex site but most will already have done a lot of the preparatory work in their safety cases. For licensed sites, in particular, a lot will depend on how the regulators want the work presented. If they are content that the safety case is the written hazard evaluation then little work is required. If they want a special document to cover the regulation then a great deal of work may be required to extract information from the safety case, present it and have the document verified and approved. A document of this nature may have to go to the Safety Committee at least once. A time and resource consuming process.

If the hazard evaluation concludes that there is the potential for a radiation emergency then regulation 5 requires a consequence assessment to “consider and evaluate a full range of possible consequences of the identified radiation emergencies, both on the premises and outside the premises, including the geographical extent of those consequences and any variable factors which have the potential to affect the severity of those consequences”. This could be a lot of work and since it all boils down to “how far out should we be prepared to implement prompt countermeasures” it is largely wasted effort as this result can be achieved with far less work.

Regulation 6 requires the hazard evaluation and consequence assessment be kept under review and updated if anything significant changes. This is no different to the old regulations.

The results of the consequence assessment must be reported to the local authority in the form of a “consequences report” (regulation 7). A meeting between the local authority and the operator should be offered to discuss this report and the operator must comply with any reasonable request for more information.

The local authority then has two months to decide on the extent of the DEPZ and to report it to the operator and regulator. This seems to be a bit ambitious since the regulators, who had more expert resource and a deep understanding of the sites’ safety cases could take several years from receipt of a Hazard Identification and Risk Evaluation document (a required document in REPPIR 2001) to determining a detailed emergency planning zone.

Regulation 9 provides the rules for setting an outline planning zone, a new feature. This is set by a series of rules but only time will tell if these rules result in clear answers.

Regulation 10 requires the operator to produce an emergency plan based on guidance about principles, purpose and content given in schedules. It is likely that operators will have to review their on-sites plans to ensure compliance but not at all clear that this effort will lead to better emergency preparedness. This review will probably fit comfortably within the one year transition period but it will require resources.

Regulation 11 sets the requirement for a local authority off-site plan. Again this will already be in place for most sites but a review against the new guidance would probably be called for. There are a number of changes to dose control and limitation (regulations 18, 19 and 20) that will need to be thought through. Local authorities may find this hard to resource.

A new element of the regulations is the concentration on keeping doses below 100 mSv. There are good reasons to propose this (the IAEA support for the statement that no harm occurs for exposures below 100 mSv, for example) but it may be difficult in some cases, particularly for unlikely severe accidents. The operators may need some time to think through this issue.

The review and testing of plans (regulation 12) is little changed from REPPIR 2001. The only issue might be the disruption to the review and testing programme caused by the introduction of new regulations.

The new regulations demand a lot of consultation, co-operation and agreement (regulations 7, 9, 10, 11, 12, 13, 14, 15, 18, 20, 21, 24). Consultees include other local authorities, category 1 responders, health authorities, public health organisations, regulators, employers, employees. This is well meaning but it takes time and resources and takes the consultees away from their day jobs.

In summary. Within a year of May 22 2019 the operators of nuclear sites are expected to produce a consequence assessment and a consequence report based on their safety cases, the local authority are expected to use this information to determine the extent of planning zones, the operator and local authority are to produce emergency plans compliant with the revised regulations and a significant number of groups are to be consulted, informed or trained.

Writing significant reports in the nuclear industry tends to take a while. They need to be drafted and verified. Reports with the importance of the two related to these regulations would normally go to the site’s nuclear safety committee for review and approval. This is a time consuming process, particularly if the committee wish to see changes and resubmission, which is not an uncommon result particularly for novel reports, as the first of these will be.

The local authority are allowed two months to consider the information provided by the operator and the layout and demographics of their area to decide upon the extent of the planning zones. They will need a process to brief their chief executive and get the conclusion endorsed within this timescale.

Emergency plans may have to be updated if the detailed emergency planning zones have changed (and if they haven’t then pretty much all of the work leading up to this stage has been pointless). Plans will have to be updated to account for the differences in expectations between the 2001 and 2019 regulations, in particular the outline planning zone, the 100 mSv reference level and changes to emergency dose terminology.

It is going to be a busy year chasing tight timescales for some in the local authority and nuclear industry emergency planning world.

Two new pieces of advice for local authority emergency planners

Local authorities’ preparedness for civil emergencies: A good practice guide for Chief Executives And A councillor’s guide to civil emergencies

The Ministry of Housing, Communities & Local Government has reissued advice to local authorities on preparedness for civil emergencies (Local authorities’ preparedness for civil emergencies: A good practice guide for Chief Executives, November 2018). This document, which is not intended to be prescriptive, lists 10 aspects it would expect to see in a well prepared authority.

In the introduction Jake Berry MP states that the nature of emergencies facing us continue to increase in variety and complexity “terror attacks in London and Manchester, the use of nerve agent in Salisbury and the devastating fire at Grenfell Tower have tested the resolve of our communities and reminded us all of the importance of local authority leadership in times of crisis”.

The section entitled “are you ready” asks nine questions about:

  • the ability of residents to contact the authority including out of hours and on bank holidays;
  • the authority’s ability to communicate risks and to warn and inform people in the area, including tourists and other visitors, before, during and after an emergency;
  • the ability of senior staff and elected members to manage in an emergency, including managing the authority’s role and as a senior officer within the strategic response and recovery mechanisms;
  • the testing of plans to ensure that they address local risk and resilience standards and describe how to maintain essential services, ensure business continuity and contain agreements with other local authorities for support in a crisis;
  • the resilience of supply chains;
  • the role of the authority within the LRF and the accuracy of the role description in multi-agency plans and the ability to deliver;
  • resource plans for no notice and sustained emergencies, including over holiday periods;
  • a knowledge of the authority’s strengths and weaknesses and where support and further resource can be obtained;
  • the ability to assess the full impact of an emergency on community needs.

The report discusses the role of the local authority in civil resilience in terms of the CCA, in which the local authority is a category 1 responder.

Importantly the regulations or guidance require that the local authority “to ensure that they can continue to exercise their functions in the event of an emergency. The duty relates to all functions, not just emergency response functions”. This appears to include the ability of an authority to provide support to any population within countermeasure zones during a nuclear emergency. “Plans should be clear about what operational support the local authority will put in place for different emergencies, and how this can be activated in and out of business hours” …. “Plans must be clear about how this support will be activated and managed. This support could include on the ground community alerting, for example, door knocking, checking on vulnerable residents, operating rest centres and providing on-going welfare support for people directly affected by emergencies”.

To achieve this all business critical functions should have robust business contingency plans for the services that the authority delivers and those that are contracted out.

An example that is pertinent to nuclear authorities is “consider building ‘all-risk resilience’ into contracts (for example, how to ensure domiciliary care is delivered during petrol shortages or severe disruption to transport networks)”. Reinforcing this is the statement that “Local authorities are expected to manage the humanitarian aspects during emergencies. This requires staff at all levels to be effectively trained to deal sensitively with victims and survivors, including their friends and family. Training and exercising reserves and volunteers builds a further level of resilience in the event of concurrent or long duration incidents”.

An example of communicating with the public given is that of Calderdale Council which utilised social media during floods in December 2015. It is claimed that the council reached over 420,000 people on Facebook and received over 1 million impressions on Twitter.

On the matter of community leadership the document states that “The public, media and politicians will also look to the council to provide information and clarity on what has happened, what is still happening and what will happen next”.

The importance of training and exercising is stressed. It builds “confidence and competence to enable robust delivery of the local authority role whether it is delivered in response or recovery”.

A list of useful documents is given at the end of the document.

This is a document that should be read by the local authority manager responsible for emergency planning and by the Chief Executive of the authority fairly regularly. It might be a useful one to have on the desk when performing periodic readiness or accountability reviews. At a mere 27 pages it makes a welcome change from some of the “door stop” guidance documents that sap the will to live.

A related document, A councillor’s guide to civil emergencieshas also been updated recently (November 2018). The forward mentions that the last version was issued in 2016 but reports that a lot has happened since then with terrorist attacks, tower fires and nerve agent attacks within the UK.

This document introduces some core terms including the definition of a civil emergency, the difference between a rising tide and a no-notice event, categories of responders and levels of response.

A number of case studies are discussed.

The overview section outlines the responsibilities of councils and individual councillors and, later, the role of leaders, portfolio holders and Ward councillors. These headings are then revisited in sections devoted to “preparedness and resilience”, “response”, and “recovery”.

Appendices give suggested questions for leaders/portfolio holders (Appendix 2) and scrutiny committees (Appendix 3) to ask.

This document is a good read and a useful resource for councils and councillors.

Human Medicines (Amendment) Regulations 2018

The Human Medicines Regulations 2012 have been amended from the 1st April (Human Medicines (Amendment) Regulations 2018) to clarify the legal position of nuclear off-site plans that rely on the speedy distribution (or pre-distribution) of stable iodine tablets and provide advice to the public to take them. This is a useful step forward.

According to the explanatory note attached to the regulations “Regulation 12 amends Schedule 17 to the 2012 Regulations so that pharmacy medicines containing Potassium Iodide or Potassium Iodate can be supplied in the event of a radiation emergency by persons acting in accordance with an off-site emergency plan or by persons listed in Part 1 or 2 of Schedule 1 to the Civil Contingencies Act 2004.”

My understanding of the situation is now that for fixed nuclear reactor sites: (Based on Sizewell off-site plan and Highland Council’s Highsafe submarine plan).

  • The Director of Public Health determines the areas that pre-distribution of stable iodine should take place in.
  • The tablets are distributed (“supplied”) by a body such as NHS England or Navy (now permitted under the revised regulation if the radiation emergency has occurred or an event has occurred that could reasonably be expected to lead to a nuclear emergency has occurred although the legality of pre-distribution could be clearer).
  • On the day the Operator (who is likely to be the first to know that there is a serious release of radioactivity) alerts the public and advises them to take the pre-distributed tablets, having prior authorisation from the Director of Public Health to do this.
  • If tablets are indicated beyond the pre-distribution range then “PHE would be responsible for coordinating the delivery of additional tablets and NHS England would be responsible for arranging distribution to the public”.

It is easier to scare than to reassure. The Shamisen project report

The EU-OPERA SHAMISEN project started in December 2015. One driver for this project was the realisation that existing recommendations on nuclear accident dose control had an almost exclusively technical focus which was directed towards the decision making process of experts while failing to consider the impact on the general populations. Both Chernobyl and Fukushima taught us that averting dose is only part of the process of protecting the public; social, ethical, psychological issues are as important, if not more so. What was needed was a set of recommendations that would contribute to health surveillance and related communication with affected populations after nuclear accidents.

The project has now reported (here). It presents a number of recommendations and, for each one, it briefly explains why they make the recommendation, how it can be satisfied and who should take the lead. This is a very good format for this type of document.

Of particular interest to me are:

R7 Build a radiation protection culture between radiation protection experts, healthcare workers, professionals and the general public. This is a very big ask. Radiation Protection is eye wateringly complex and it takes several hours to explain the basics to people with a good science education. The big questions are how are the healthcare workers going to find the time to listen and how are you going to convince the public that they need to devote the time and effort to learning. After an accident in their area I think we’d have their attention but not before. This is a laudable ambition, teaching materials can be written (indeed many good examples already exist) but after that there are no quick wins.

R8 Establish early response and communication protocols with responsibilities and roles clearly laid out. Engage relevant stakeholders in the establishment of these protocols, and prepare the necessary material and channels to communicate with the public (including social media). This is part of the preparedness phase. Much of this is already part of basic emergency plans. Off-site plans invariably list who should be alerted and define the roles and responsibilities of responders. Maybe more could be done to prepare information and discuss how it could be presented to the public on the day of an event and in the days and weeks following an event.

R10 Prepare and facilitate training and education material and resources adapted to healthcare and other professionals, as well as other stakeholders. This is another laudable ambition to pre-position healthcare, community leaders and teachers with suitable knowledge and teaching materials ready to step and inform and reassure the public if the worst happens. Again the problem is one of time and focus. Healthcare professionals have a lot of competing issues to consider as they strive to support the community health.

R13 Foster participation of stakeholders and communities by engaging them in emergency preparedness, including planning for socio-economic health surveillance and, where appropriate, epidemiology. Again the industry and the government already does a lot in this area with regular meetings with community groups and community group representation on multi-agency emergency planning meetings. This tends to be more about the arrangements to promulgate and alert and support early countermeasures rather than socio-economics and epidemiology. (Having said that health physics is a challenge to teach it must be recognised that it is relatively straightforward compared to epidemiology).

R14 Ensure prompt sharing of accurate and reliable information (e.g., plant conditions, radiation dose, radiation protection actions) between nuclear plant representatives, authorities, experts and the population. The paper has a great quote here; “it is easier to scare than to reassure”. Talking about the tendency of misinformation to quickly fill any gaps in communication it reports that “a recent study found that, during the Zika virus outbreak, the most popular social media health stories were the least accurate”. This isn’t a surprise but it does focus us on the reality of public communication – it is difficult. The authors conclude this section by saying that “the benefits of online information offer the public a unique opportunity to learn about nuclear power, which may outweigh the costs associated with “internet cacophony”.

I find the recommendation R18 Provide support to populations who wish to make their own measurements, recommending reliable equipment and resources (e.g., apps, social media, information centres) that can contribute to the characterisation of population exposure and its evolution a little hard to agree with. Radiation detection is relatively easy. Radiation measurement is quite difficult. Interpretation of radiation measurements in terms of harm is difficult. There could be benefits from providing groups of people immediately affected by the incident with a group EPD to give a quick assessment of their dose during the acute phase, and providing everyone who returns from evacuation with a personal TLD (collected and read by the authorities) to assess their doses systematically. But I would hesitate to encourage unskilled people to wield unfamiliar radiation monitors and use the results to affect their behaviour.

The recovery phase recommendations all have merit and consideration of this document should be included in any recovery phase planning effort.

What do we need to do better as a result of this advice?

I think that the idea of building up radiological protection knowledge capital prior to an event is sensible but difficult. Encouraging healthcare professions, community leaders and people the community might trust such as teachers is always going to struggle against competing calls on their time and attention. Given that other threats such as flu pandemic, other health scares and themes such as mental health, diet and obesity are more likely to impact they are more likely to take the training time of these people. The industry’s outreach and information programmes should continue.

Early response tools, such as briefing material, are often spoken about and nuclear operators tend to have trained Media Technical Briefers to explain the complexities of nuclear accidents and health implications on the day. A review to see if more can be done, particularly with emerging technology and communications channels, should be undertaken periodically.


This report is well thought out, well presented and valuable. It deserves to be read by nuclear emergency planners and those responders with responsibility for advising and supporting members of the public before, during and after an accident.

Protective Action Guides

In the United States the Environmental Protection Agency issues “Protective Action Guidelines” (PAGs) which satisfy the same role that Emergency Reference Levels (ERLs) do in the United Kingdom. The Protective Action Guide (PAG) manual contains radiation dose guidelines that would trigger public safety measures, such as evacuation or staying indoors, to minimize or prevent radiation exposure during an emergency.

The 2017 PAG manual is a significant document (101 Pages) which has chapters devoted to:

  • Early phase protective action guides;
  • Emergency worker protection;
  • Intermediate phase protective action guides;
  • Planning guidance for the late phase.

For the early phase it provides a PAG for shelter in place or evacuation of the public of 10 to 50 mSv projected dose over four days. This is accompanied by a note that suggests that actions should start at 10 mSv projected dose and take whichever action or actions result in the lowest exposure for the majority of the population. This is broadly consistent with IAEA advice and UK practice although the UK ERLs are based on averted dose rather than projected.

 The stable iodine PAG is 50 mSv to the infant thyroid from exposure to radioactive iodine.

Emergency workers should be limited to 50 mSv over the entire response or per year unless there are extreme circumstances (such as saving life or preventing a significant release).

The report warns that: “In the early phase, there may be little or no data on actual releases to the environment and responders may have to rely on crude estimates of airborne releases. Decision time frames are short and preparation is critical to make prudent decisions when data are lacking or insufficient.”

The report suggests that the public should be advised to cover their mouth and nose with “available filtering material” when particulate activity may be present. This advice is not given in the UK.

It is also suggested that where particulate activity is present but below the PAG level the public are advised to “stay indoors to the extent practical” to reduce their dose but make a judgement if they need to go out for any reason. Such advice is apparently given on days when air pollution is forecast to be bad. Again, this is not something I’ve heard mentioned in the UK.

 A discussion about the relative merits of shelter in place and evacuation concludes that “Sheltering-in-place should be preferred to evacuation whenever it provides equal or greater protection. Sheltering-in-place followed by informed evacuation may be most protective”. It reports that populations that are aware of the evacuation alerting mechanisms and plans are more likely to successfully evacuate than unprepared populations and further reports that many areas are improving their communications processes and public training. The need to have special plans for needy groups such as schools, institutions and those without their own transport is noted.

On iodine tablets the report suggests that minimum doses for each age (weight) group is ideal but that, if this is too challenging logistically and in terms of communication, then a full dose can be given to all without great risk.

Interestingly it suggests that adults over 40 years old would only benefit from stable iodine if their projected thyroid dose is of the order of 5 Sv where it can be used to prevent hypothyroidism.

Stable iodine given to pregnant women also protects the foetus but repeat doses should be avoided if possible to prevent foetal thyroid complications. (In the UK it is expected that a single dose of stable iodine will be adequate because either the release will have stopped or the affected members of the public should be evacuated within the 24 hours that the first dose provides protection for).

Breast feeding mothers can reduce the radioiodine in their milk by taking the usual dose of stable iodine. This is useful for reducing the baby’s dose but does not protect them from directly inhaled radioiodine for which a small dose of stable iodine can be administered.

Section 2.3 discusses the process of estimating dose projections based on source terms, atmospheric dispersion and release prognosis. Section 2.4 discusses contamination and environmental monitoring.

Subsequent sections discuss the control and limitation of dose to responders and recovery workers and doses in the later phases of the event, including from food and water, once the release has stopped. Of interest is table 4-2 which summarises a discussion about the circumstances under which people can be allowed back into an area, either for remedial work, use of critical infrastructure, to access business and homes to recover property.

On the whole the advice given in this report is similar to that given in the NRPB’s ERL documents that are used in the UK. It contains some interesting and useful discussion.

“keyhole” countermeasure zones


Heatwave plan for England

PHE and NHS England have issued new advice on planning for heatwaves (here).

The purpose of this heatwave plan is to reduce summer deaths and illness by raising public awareness and triggering actions in the NHS, public health, social care and other community and voluntary organisations to support people who have health, housing or economic circumstances that increase their vulnerability to heat.

It states a concern that periods of hot weather will become more common in the UK as climate change kicks in leading to increased deaths among several identified vulnerable groups and some infrastructure issues.

The Met. Office has a mechanism for promulgating alerts about forecasts of dangerous weather conditions and this is explained in the context of heatwaves and is linked to five levels of heatwave readiness.

We should be trying to make our public spaces, buildings and homes cooler by design, including tree planting and open water features. Cooling homes by appropriate shading and ventilation but also by choice of colours for curtains and roofs.

On the day we should be avoiding exercise in the midday sun, drinking plenty of water but less caffeine, wearing cool clothing and looking out for our neighbours.

It is a bit light on what employers can do to protect their workforce without sacrificing more productivity than required but, if they read the report, they’ll pick up some useful tips.

The revision of REPPIR

With the Radiation (Emergency Preparedness and Public Information) Regulations 2001 due to be reissued in line with the 2013 EU BSS (See HSE note), interest turns to the discussion about how to determine the appropriate level of emergency preparedness for nuclear sites.

Currently REPPIR requires that the risks posed by the site are assessed, reported and periodically reviewed. If there are identified potential fault sequences that exceed thresholds of both probability and severity then off-site plans are required.

The threshold for probability is “reasonably foreseeable”. In the REPPIR guidance (para 50) it is stated that “In the context of a radiation emergency, a reasonably foreseeable event would be one which was less than likely but realistically possible”. ONR have avoided accepting a numerical value for the threshold of reasonably foreseeable (see, for example, para A20 -A22 in an ONR TAG).

ONR’s description of safety cases tells us that (Para 607) Design basis analysis (DBA) leads to an understanding of the plant and a design proven “so that safety functions can be delivered reliably during all modes of operation and under reasonably foreseeable faults”. Combining this with (Para A.9) “only faults with an initiating fault frequency (IFF) greater than 1 x 10-5/yr need to be considered for DBA” suggests that a frequency of 1 x 10-5/yr could be proposed as the limit of a “reasonably foreseeable” initiator.

1 x 10-5 per year is also implied in the ONR Tolerability of Risk Document ToR and in the national risk assessment policy sponsored by the Cabinet Office as a boundary between events that should be prepared for and those that are too unlikely for detailed planning.

The threshold for severity used in REPPIR 2001 is that of a Radiation Emergency. This is defined as a situation in which a member of the public could receive an additional radiation dose of 5 mSv in the year following initiation. There have been difficulties interpreting this requirement as the public dose assessment depends on the individual habits assumed.

There is a general principle in radiological protection and emergency planning that any action taken by authorities should to do more good than harm. In the UK we use the Emergency Reference levels (ERLs) to decide if a countermeasure is warranted by comparing the avertable dose with the relevant ERL. We can therefore state that the imposition of a countermeasure is not necessary, indeed not appropriate, where the avertable dose is below the ERL and a detailed plan to implement a countermeasure is therefore not needed where it is not reasonably foreseeable that the threshold will be exceeded. Thus the severity threshold for requiring a plan can be based on whether or not the existence of a plan would enable the imposition of prompt countermeasures which could avert an ERL’s worth of dose that could not otherwise be averted.

Concern about faults too unlikely to appear in the DBA but more severe than the reference accidents leads to the demand for the ability to extend countermeasures beyond the detailed plan if required. However, it is realised that spend to enable this quickly becomes grossly disproportionate to the potential gain.

While the situation analysis and decision making process provided by the detailed plan can consider a wider area or longer duration fault, the question is whether or not countermeasures can be applied rapidly enough over a wider area to be effective. This would depend on the nature of the fault including the amount of activity released and the time structure of that release.

Again the question of the probability of the limiting fault to use in extendibility scenarios arises. In various safety methodology documents IAEA talks about a “screening probability level” (SPL) of probability below which there is no point analysing faults. So far as I can find IAEA fails to suggest a value. There is a claim in the literature that the US DOE suggest 1 x 10-6 for aircraft crash onto nuclear facilities. It is suggested that future UK guidance on emergency planning recommends a SPL for emergency planning (extendibility) and that this value should not be lower than 1 x 10-6 or, at a pinch, 1 x 10-7.

Emergency planning then becomes a question of having detailed plans to implement those countermeasures that might avert more than an ERL of individual dose for the set of reasonably foreseeable faults – defined as being more frequent than 1 x 10-5 per reactor year (making allowances for reasonable cliff-edges) and outline plans for faults down to maybe 1 x 10-7 per reactor year. Estimations of avertable dose against downwind distance can determine a sensible limit to the countermeasure zone (which regulators may then choose to inflate within reason for non-technical purposes).

HERCA-WENRA Approach to cross border cooperation in the event of a nuclear accident

The Association of the Heads of the European Radiological protection Competent Authorities (HERCA) and Western European Nuclear Regulators’ Association (WENRA) have jointly considered cross border cooperation in the early stages of a nuclear accident. They propose a mechanism based on shared technical understanding, coordination and mutual trust.

A workshop is reported (here) which was attended by representatives from ONR and PHE CRCE. It is not known to what extent the UK participants agreed with the published conclusions of the workshop.


The aim of the project is to ensure that when an accident affects neighbouring countries the countermeasures recommended in each country are comparable as described in the figure above (taken from HERCA WENRA document). It was reported that some countries have clear guidance on how to set countermeasures that might make this harmonisation more difficult.

The report suggests that (Conservative) evaluation of the potential hazard area favours a common understanding and coherent communication internationally and helps to give early assurance to populations outside this area. It does not seem to have considered that an excessively large countermeasure zone would hamper the ability to focus resources on those in most need of support and may unduly inconvenience and worry people within the zones but relatively safe from the radiation hazard. This seems to go against the ICRP principle of justification that “any decision that alters the radiation exposure situation should do more good than harm” (ICRP 103, page 88).

The report states that “HERCA and WENRA consider that in Europe:

  • evacuation should be prepared up to 5 km around nuclear power plants, and sheltering and ITB up to 20 km;
  • a general strategy should be defined in order to be able to extend evacuation up to 20 km, and sheltering and ITB up to 100 km;
  • nuclear and radiation safety authorities in Europe should continue attempts to promote compatible response arrangements and protection strategies amongst the European countries”.


 It later explains that the 5 km evacuation and 20 km sheltering and taking of stable iodine prophylaxis is a precautionary approach for situations where core melt is judged possible. It also states (Section 8.2) that shelter is preferred to evacuation if the evacuation cannot be completed before the release starts.

The wider zones are stated to be appropriate where, in addition to core melt, the containment integrity is lost.

Since sheltering cannot be implemented for a very long duration, the report proposes that it should be prepared immediately but only implemented a few hours before the time of release. The report does not develop the discussion of the implications of a warning time. It would give an opportunity for people to collect stable iodine tablets from a local distribution point and to prepare for shelter but would also possibly trigger an uncontrolled evacuation and panic buying of food and bottled water. Great care should be taken when considering recommending shelter “once the release starts”.


The harmonisation of countermeasure advice across national borders in the event of a transnational release of radioactivity is clearly desirable. This can best be achieved with shared technical understanding, coordination and mutual trust but also requires the same decision making process when facing with an uncertain radiological situation and limited time to make and implement decisions. The approach of pre-agreeing on the largest area based on generic conservative decision making runs the risk of applying disproportionate countermeasures on the day and saddling society with disproportionate emergency preparation costs. A link to the site’s safety case seems much more appropriate.

It is not clear where this grouping’s remit for advising countermeasure distances comes from, the basis for their distances is unexplained as is how they relate to EURATOM and IAEA. So while their thoughts on cross-border cooperation and information exchange are valued, their thoughts on countermeasure distances do not seem to add value to the discussion.