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.

Summary

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.

figure

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”.

Discussion.

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.