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15/3/2011 - Nuclear events in Japan – Radiation Dose ‘high enough to effect human health’

Good morning all. Well it is 0400 on Tuesday morning in the UK and I find myself writing this before I get up (could not sleep). The reports coming in from Japan and specifically details about the Fukushima plants are disturbing - there is no denying that. I find myself looking at the story unfolding and having to concede that the state of the plants seem to worsening more than I would have speculated. Regardless of whether I am ‘pro nuclear' or not, I am not going to jump into a hole and try and deny anything else.

The last few days, i.e. over the weekend and Monday (as it was an office day) I have found myself becoming quite involved in the media and watching closely what has been going on. From this point forward this will be harder to do as I am actually working (!) - I.e. client visits. So I will probably not be as up to speed as I would like regarding this evolving nuclear incident. However, before getting on the road I wanted to write down a few words about ‘dose' because I think it is important (and the media is full of all sorts of values now).

Events in Japan

Before doing that, I would just like to point you to the following article on the Depleted Cranium website ‘While everyone was focused on the nuclear plant'. For me this article puts into focus the tragedy that is unfolding in Japan, even at a time when the nuclear issues appear to be worsening. I will let you read the article but some highlights on the site are:

  • 2800 confirmed dead
  • Many more missing and feared dead
  • Hospitals damaged (without electricity or water)
  • Infrastructure destroy (rationing of water / electricity etc)
  • Number homeless probably in the millions
  • Millions of businesses destroyed or out of action (including major world manufacturers)
  • Dam failures
  • Oil refinery fires
  • Etc

If you had been away on another planet and had just come back and picked up a newspaper, or turned on the news, you would be forgiven for linking the above tragic list of outcomes to the nuclear incident - not least because most of the media publications are almost 100% on the nuclear story. Now, I really am not downplaying the nuclear event (I don't think you will find I have in the earlier posts if you read them carefully), but take a look at the list again and be clear that none of these were nuclear related.

So, accepting that this is not nuclear related - what is then? Well clearly the issue is down to the health effects of ionising radiation. I do not have the time (or energy this morning) to provide a fully checked (and peer reviewed) description of the science surrounding health effects of radiation. The problem is that I can pick and choose from a multitude of training materials, but that simply does not work when you have such a potentially diverse audience. So what follows is a quick brain dump of ideas and thoughts, mixed with some media files (which are probably too detailed for the majority but I have nothing better).

Critical persons exposed

It is first important to consider who is being exposed and how. There are broadly two groups of people: nuclear plant workers and members of the public (I include general emergency workers, relief workers and the media in the second group). Those most likely to be exposed are clearly the plant workers - they are nearer to the plant than anyone else.

Units of Dose

This is where things can get a bit complicated (well at least in a short article such as this). What I am going to do is first direct you to two YouTube videos that I have had produced. If you cannot get YouTube because you are at work (etc) then sorry - perhaps you can catch them later. Parts 1 and 2 on Radiation Dose are below. Take your time over this and perhaps watch a few times.


So you see the base unit of dose is the Gy (Gray) - the absorbed dose.

Generally speaking we should really be talking about the Gy (in relation to this incident) when discussing deterministic radiation effects (i.e. as reported in the media ‘doses that are harmful to human health' etc). This is because the probability of cancer at some later date is really immaterial when one is looking at radiation sickness (which might be life threatening). When we use the unit of Sv (Sievert ), and specifically in the context of Whole Body Dose (either from external or internal radiation), then it is a derived quantity which reflects future risk of cancer - it is not really a dose at all.

When we measure an external radiation field using a radiation monitor, and looking specifically at dose rate, we are not really measuring effective whole body dose - it might actually be ‘ambient dose equivalent'. However, for an emergency situation, a dose rate monitor that reads a dose rate of 1mSv/h is going to be fairly close to reflecting your possible radiation exposure (i.e. your whole body dose) - on the assumption that your whole body IS being exposed (and externally only).

Internal Radiation Exposure

Things get more complicated when looking at the possibility of ‘internal radiation' - that is, the intake of radioactive material into the body. No longer can you simply ‘walk away' because that radioactive material is now inside you. The following video (again on YouTube and with no audio) provides a good basic description of this.

Dose Limits

In the media there have been various reports of doses ‘8 times higher than the dose limit' (for example). We really need to be much more precise about what we mean when presenting such figures.

I will assume that you have been able to watch the two videos on Dose. You will note that there is no ‘dose limit' for deterministic effects. There is, however, what we call a threshold effect (that is a dose delivered over a small time scale that would lead to clinical effects - radiation sickness - and possible death). Now, what I should really be doing now is talking about the Gy if I want to start discussing these threshold effects - but for the purposes of this blog article I will state that 1Gy = 1Sv (for beta, gamma and x-ray radiation). This relationship does not stand for the case where there is an intake of internal radioactive material which emits alpha particles - such as for Pu-239. It is beyond the scope of this article to go into alpha radiation, other than to point out that as far as I can tell (at this time) it is unlikely to be an issue with the reactors in Japan.

So accepting that 1Gy=1Sv I will just now work in Sv (also noting therefore that for the US, 100 Rem = 1Sv). The onset of some form of observable ‘radiation sickness' (from the point of view of the person exposed) is about 1Sv. You may feel slightly nauseous and generally not well - but you can see how this could actually be shock and distress (there has been an earthquake after all). As the whole body dose increases then the sickness will manifest itself more (vomiting etc). In very severe cases, (e.g. 4-6 Sv over a few hours at most), then the risks of dying (without medical intervention) increase (as the severity just gets worse with dose).

Now, that might all sound scary but just be aware of the order of magnitude here:

1Sv = 1000mSv = 1,000,000 micro Sv

Furthermore, the media are not very good at reporting dose. It is no good saying : 8000 micro Sv, you need to show how that might be received (e.g. is it actually 8000 microSv/h). Even when you have given that figure it does not mean that you will receive that level of exposure (let us assume for a moment that it is an external source of radiation). For example, are you there for the whole hour or do you move away? Is the source of the dose rate a moving radioactive plume (so it passes you by)? This is further complicated by what is actually presenting the dose. For example, if you were covered in a layer of gamma emitting radioactive contamination (e.g. Cs-137 contaminated dust), then you will continue to be irradiated (externally) by that radioactive material until it is removed. Of course, removal of that contamination also yields a potential internal radiation hazard (which is why a mask would be worn).
So, we have seen that dose limits are not applied to effects that will cause clinical harm (i.e.  ‘levels that can impact human health ' - as reported by the BBC this morning here).

Actually, if I were to be pedantic then I think that phrase (from the Japanese Chief Cabinet Secretary Yukio Edano), as reported by the BBC, is confusing. It is confusing because with respect to non-deterministic effects (stochastic effects), where cancer is the issue, there is indeed no ‘safe level' if you look at how the science works. This is based on the LNT model (watch the above Dose videos if you are not sure). Therefore, when a dose limit (based on stochastic effects) is breached or exceeded - which is what I think the Chief Cabinet Secretary is talking about - it does not mean that things ‘suddenly become dangerous' - i.e. sudden step change in the impact on human health. If the dose limit is exceeded then it simply means that the level of risk (which is built into the derivation of the dose limit) that is deemed acceptable by society, is exceeded.

Like it not, acceptable risk will also be determined by circumstance (e.g. there are no dose limits for medical radiotherapy).

Looked at another way, if you smoke say 10 cigarettes a day then that could be turned into a dose limit. The limit would be set by some official that suggests that the risk of smoking and getting a cancer later on in life is acceptable to society etc. Then, breaching that dose limit (say smoking 15 cigarettes a day for a month) does not then push you over a threshold (i.e. to levels that can impact human health), it just increases the risk of cancer some time later in your life by a very small amount.

The current setting of dose limits (based on the recommendations of ICRP) work in a similar way.

So, what are these dose limits are what do they mean?

The following dose limits (for whole body dose - will leave organ and extremity dose limits for another day as they are based on equivalent dose) are as follows:

1mSv / year - member of the public
20mSv / year - occupational exposure

The above are based on workplaces (i.e. working with ionising radiation) and are internationally recognised. There are some small differences and allowances (e.g. in the EU for example you could receive 50mSv/year as long as your 5 year dose did not exceed 100mSv). The above dose limits cannot really be applied to accident situations because the ‘benefit / risk' equation (AKA detriment) is different - but for our purposes they are good enough.
I hope you see, even in this small blog article, that the whole concept of dose can be treated simply or in some considerable detail. Treating it simply can lead to assumptions by those that read the newspapers that things are much worse than they really are. Delving into the detail can also be counter-productive , I have tried to get the balance right - have I?

Dose / Risk

Again, I am applying much simplification here this morning. The basic risk (ignoring age, public vs workers, discussion on hereditary etc etc etc) is about 5% / Sv (for cancer). Put another way, for an effective whole body dose of 1mSv of ionising radiation, the risk of cancer is about 1:20000. The simple relationship between dose and risk is assumed linear (as shown in the above Dose video) - there is much discussion in the scientific community over this!!

The risk of getting cancer (from all known causes) and dying from it is about 1:4 (25%) .

I also do not have time now to discuss specific cancers (e.g. Thyroid - which are a targeted cancer since radioactive Iodine is preferentially taken up).

So let me finally try and put the value ‘1mSv' of dose into context (I base this on current ICRP recommendations, so back off if you want to discuss the problems with their approach - that is for another day too!). In looking at the 1mSv we can assume that this has been delivered either from an external radiation field or from internal incorporation of radioactive material.

The value 1mSv is about one half to one third of what you getting anyway from background radiation - depending on where you live in the world.
Therefore, whilst highly undesirable (and I really mean that too), an exposure of a few mSv (effective whole body dose) to members of the public in Japan - when consideration is given to what they are going through, and what they are going to go through in the coming days, is trivial.

The doses that some of the workers at the plant are receiving are clearly not trivial (and are intolerable if they have approached deterministic levels).

Final thought (for now)

I would guess that those injured persons (from the earthquake) who are lucky enough to survive and get to a hospital (if it is working and intact), will probably receive more ionising radiation from their CT scan than an average member of the population who is exposed to any plume of radioactive material coming out of Fukushima. It does not make it right, or justified, nor does it excuse any bad practice, design fault (or dare I say the decision to build nuclear plant in known active earthquake zones). However, what it shows (at the time of writing where events are still unfolding), is that the preoccupation with ‘nuclear' and ‘radiation', risks losing sight of the bigger tragedy.

14/3/2011 - Nuclear event in Japan: More comment, perspective & information links

Since this site generally discusses radiation related matters it is natural that I have an on-going interest in what is happening in Japan - there is no doubt that the nuclear incident (which is still evolving) is tragic. However, before commenting further on this, I would like to emphasise my shock and distress at seeing the wide scale devastation that has been caused by the earthquake and the tsunami. At a time like this, when the emotive matters which naturally surround all things radiation are dominating the media, we must not set aside the enormity of this natural disaster.

Current Media Reporting

Take a look at the following footage from the BBC that I discovered early this morning ‘Japan earthquake: Footage of moment tsunami hit'.

I personally find this much more disturbing, a ‘nightmare' situation in fact, than anything I have seen regarding the on-going nuclear events at Fukushima. Why is that? Probably because I am not that keen on water (swimming) and the thought of being trapped and waiting for that wave to engulf everything is truly scary. It is difficult to imagine how many people lost their lives - existence wiped out in an instant - to use a more techy term we can sort of call it ‘deterministic'. The threshold of what the body can stand and the ability to breath etc is exceeded - obviously.

Seeing and feeling is believing ?

One of the things that is particularly obvious in the footage from the BBC is that little imagination is required - you can see everything in full colour. The same cannot be said for nuclear and radiation issues. All you see, for example, is an explosion (which I concede is dramatic). The evidence you have as to what effect this might have on the environment and the population is then down to what you read, what you hear on the television or radio, what you gain from browsing the internet and what you really know about the effects of ionising radiation. For ionising radiation is this ‘thing' that you cannot see, touch, smell, taste but ... " it's there.." Combine this with details of evacuation zones, pictures of kids being monitored by adults dressed in white coveralls and wearing masks - and the imagination and worry is amplified 100's of times.

I am not knocking this - it is unavoidable. However, with respect to health and the environment, the real obvious question is going to be ‘what are the effects'. That question cannot at this stage be answered completely, but already there are some clues out there. The problem I have is that already many commentators (media, anti-nuclear groups etc) are saying, on the basis of what we have seen on the news, that nuclear power is ‘unsafe' and ‘not a risk worth taking'.

My question is - what is that based on? It cannot and should not be based on the fact that the plant has failed and exploded? Why do I say this? Well consider this - when an oil platform blows up do we say we must close down the oil industry? When a chemical plant explodes, do we say we should not process chemicals anymore? When a plane crashes do we say - no more flying? The reason we do not say ‘no' to these is that we (the public and media at large) understand the risks (or at least more than nuclear and radiation issues are generally understood). In many cases that is because what we see, hear, touch and smell (perhaps not literally but as ‘shown' via media reports) it is something tangible - we can grab hold of it, and it can grab hold of us (literally in the case of the terrible tsunami as shown in the media report above).

So why now are so many reports in the media fixated on the nuclear event in Japan? Why are many of the anti-nuclear groups now saying that nuclear power generation is not worth the risk? Quite simply it is because they do not understand the risks - and they are frightened by what they do not understand. It is not that surprising when you think about it - this invisible scary hazard that creeps up on you?!

Health risk / effects from ionising radiation

So as not too sound arrogant (I hope I am not), to be fair I think the international community within my field of radiation protection is also still not clear on the risks of ionising radiation. A ‘per unit' dose of radiation to the whole body might yet be proved to be more carcinogenic than currently thought. But by the same token, much of the research shows that the opposite may be the case, and in fact we have overestimated the risks. Despite the uncertainty, most are certain we are within the right ‘ball park' (this must be so because we live with background radiation which in the UK, on an annual basis, is greater than the average worker receives whilst working in the UK nuclear industry).

Appreciation of the level of environmental or personal risk associated with this nuclear event is not helped by the liberal use of ‘facts' and ‘values' within the media. What does 1000 micro Sv mean to someone who is not an expert in radiation protection? Does it sound scary or serious?

Use of language & typical terms (..but do you understand them)?

Furthermore, the careless (but not surprising) use of phrases like ‘radiation is spewing from the reactor' does not help either. Radiation does not spew - it is either particulate in nature (alpha, beta) or electromagnetic radiation. Even then - those particles (say alpha and beta) do not ‘spew' either - it is contaminated material (dust, water, steam etc) which contains the radioactive substance that is moving. This then leads to media reports that ‘workers received treatment for the medical effects of radiation' - when the actual picture was that the same workers were ‘washed down' (decontaminated) to remove the contamination from their outer clothing and skin. It is therefore rather extreme to suggest this is medical treatment - but picked up by the media and expressed as such, you can see where the worry develops.

Many of the media sites are currently talking about radioactive caesium and iodine. Significant activity of either of these - outside or inside the body - could be harmful to health (and in the worse case cause deterministic effects). However, that is just not the case in this event - and this was also the same for almost all ‘victims' of Chernobyl. Furthermore, note that I-131 (Iodine-131) is actually administered to the body during medical diagnostics and treatment, and Cs-137 (Caesium-137) is used in the sterilisation of blood [I concede in the case of Cs-137 it is a sealed source - however, unlike much of the media, I am clarifying what I mean rather than leaving you with an arbitrary statement].

Radiation effects: clinical or risk based?

Based on what I have seen and read (and I know this could change, so keep that in mind), there are no reports of workers at the plant receiving deterministic (threshold) levels of ionising radiation to make them sick. Furthermore, the probability of a member of the public in Japan receiving an exposure of ionising radiation which would lead to such medical effects (deterministic clinical injury) is so negligible as to be discounted (but I would of course say that...).

So, what is the big deal then? Well, we come back to the issue of ‘risk' - noting that this is derived from the unseen hazard (unlike the tsunami). There is a risk that some members of the population may receive a dose of ionising radiation by either direct exposure to contaminated material or perhaps by the intake (by inhalation or ingestion) of that radioactive material (e.g. if there was a plume). Again, that will seem scary because it is unseen (unless the plume is visible I guess). The effect of this intake will be completely and utterly undetected or perceived by the individual - in terms of health effects. There will be negligible health effects ("but" you say, hold on a minute). Using current models of radiation exposure at low levels (known as stochastic effects), all we can do is to give you a statistical risk of a health effect (perhaps cancer) that might (I said ‘might') occur perhaps 5-10-50 years into the future. Again, that will seem scary to some because if you survived the tsunami than you can say ‘phew', whereas if you have this ‘chance of death' hanging over you for many years you might not want to deal with that thought (of course, chance of death is 100%!).

It is too early to provide much detail on the very very small risks that I am sure this event will present for the population at large. I also will add that I think the risks to the general population at large from the Chernobyl reactor incident were also slight too - indeed, the mass movements of population probably did more harm to health then the radiation ever could - but that is a debate for another day.

For the time being, keep this imperfect (but easy to understand) relationship in mind:

The cancer risk of a 1mSv (that is 1000 micro Sv) whole body radiation is about the same as that expected if you smoke 40 cigarettes (yes two packets of 20).

Compare this figure with what you read / hear in the coming days and weeks.

Another example of shocking BBC Reporting

The current (14/03/2011, 0730) BBC headline link on the front page reads ‘ There is nothing here, everything is gone '. You think an actual story on the devastation and suffering in Japan. You click on the link which takes you to a story with the title ‘ Explosion at Japan Nuclear Plant '. The story then has very little to do with the title (it is then actually reporting what I think are the major issues). See here:

Very disappointed indeed with the standards of reporting in the main media.

More information

I recommend the following sites if you want a detailed discussion on the nuclear plant aspects of this event.

13/3/2011 - What IS it about Nuclear and Radiation issues that scare / raise media interest?

Please do not look for an answer here, because I really do not know what it is. Obviously the question relates to the on-going nuclear incident at the Fukushima plant in Japan. The problem in trying to answer the question I raise is that it quickly descends into a pro-nuclear or anti-nuclear stance.

So let me tell you where I am at (sounds like Dragons Den!) - I am generally a Pro-Nuclear individual who sees the benefit of nuclear energy. To be more precise, I see the benefit of using ionising radiation (including radioactive & nuclear materials as correctly defined) in power production, industry, medicine, security and so on. I think even ‘anti-nuclear' individuals, as might be portrayed in the media, would if they sit back and think about it, accept the use of ionising radiation in some cases (e.g. medical treatment). If they want a PET scan then they will need F-18 to be made in a cyclotron (type of accelerator), and if they want a Tc-99m brain scan they will need that radioactive material (which is made in a nuclear reactor).

However, whatever side of the fence you are on means that answering the above question I raise takes on bias. For example, reading the reports and delving into the science regarding the Chernobyl incident (25 year anniversary this April), appears to indicate (to me) that the overall health effects (to date) were much less than feared. If you take that a step further and look at the whole issue of Linear No Threshold (LNT) models for cancer induction at low doses and low dose rates, then you can see why the conclusions (which I accept) might be so. However, if I am anti-nuclear then there is a whole load of literature I can go to which will tell me the story I want - that is, that the health effects from the Chernobyl event are massive and ‘we have not seen anything yet' (i.e. many more cancers to show up in the future).

So you can see where the problem in answering the above question is - what do you want to believe? Do you want to believe ‘me' (generally pro-nuclear) or someone else (perhaps who is very much anti-nuclear).

I can give you facts and figures, talk about background radiation - but not at the moment, it is not the right time because I know there will not be the penetration required into the general media. So what ends up happening is I, and people like me, end up ranting on ‘generally pro-nuclear' websites, whereas the anti-nuclear lobby do the same on their websites. For some reason, and I am trying not to make a generalisation here (but maybe I am?), the media seems to be stuck in the camp that the radiation and nuclear issues in Japan are newsworthy and must make the headlines.

Units & Rates

What is also very worrying in the media, and on many twitter feeds / social networks is the casual use of units and numbers - reported as ‘facts' - as if they have some significance? I have then seen mSv used when it should be micro Sv (1mSv is 1000 times greater than a micro Sv). Also, a dose (like 1 micro Sv) is no good without a rate (1 micro Sv/h , 1mSv per day) - or a statement of total dose (i.e. the total dose was 1mSv effective whole body). This might all seem too detailed for the general media, but without the detail the headline figures and values mean absolutely nothing (but might still appear scary).

I am not saying that the nuclear incident in Japan is not newsworthy or significant - it should have front page news of course. However, just look what has happened in Japan - do we all really believe that the nuclear and radiation issues being reported are scarier than what Japan is going to have to deal with over the next week, month and years (and I am excluding of course the nuclear issue here)?

If you are interested then you might like the following website:

You will clearly see what camp the website falls into.

12/3/2011 - Abnormal rise of radioactive dosage value at site boundary (INES Level 4)

Things are moving very quickly at the moment - this is the latest on the IAEA events scale.

This is taken from the IAEA event log.

Abnormal rise of radioactive dosage value at site boundary (INES Level 4) - Japan


On 12 March 2011, Fukushima Dai-ichi Nuclear Power Station Unit 1, which is in rated power operation, has generally shut down around 2:46pm (JST) in March 12, 2011 because of the Tohoku regional Pacific Ocean Offshore Earthquake.

After that, the radioactive dosage value at site boundary had exceeded the limit value.

The incident log for the above event can be read at the following link: IAEA News (You may need to log in as a guest).

Ionactive Comment

Not a lot being said in this report, but appears to provide a provisional INES level 4 rating. This can be translated as ‘an accident with local consequences'. Clearly that rating may change one way or another as time progresses.

My understanding is that they are currently pumping sea water and boric acid into the damaged reactor. This is designed to cool the fuel whilst providing a neutron poison to stop any criticality occurring. My guess is that this is not part of the set emergency plan (that the site would have to have) - so clearly indicates a catastrophic event. That said, I currently understand that the reactor vessel is intact, but because of the explosive damage they manually have to cool it (presumably because control systems, pumps or lines are out of action?).

As serious as this nuclear event is proving to be (by nuclear incident standards), I am still somewhat disappointed at significantly reduced coverage (on Sky / BBC) of the ‘earthquake event'. Railways, airports, infrastructure wrecked. Houses destroyed many 1000's of lives wiped out. It is true that one event is totally ‘by act of God' (if that is what you believe), and the other is influenced by ‘us' (with a little help from nature). Nevertheless, the ‘nuclear' and ‘radiation' issues are still the most dominant feature.

Once things are stabilised we will have to ask ourselves - what is it about radiation and nuclear issues that is so terrifying. Is it, for example, that it is man-made?

The media / twitter (etc) at the moment are talking about ‘radiation released', ‘radioactivity released', ‘issue of KI', ‘doses 1000 times normal' and so on. The problem I have with this is that unless you can interpret what that all means - then it is meaningless. The fact that radiation has been released (clearly undesirable) is for some, (and particularly those who are very much anti-nuclear), reason enough already to say ‘enough is enough'. This really means that any level of ionising radiation that is released, and any level of dose given to the public, is reason to stop using nuclear energy.

As unpalatable as this might be - everything in life has a risk - as a society we have to decide what risks we are willing to take. I guess it will not matter to many, if down line we calculate (for example) that the maximum dose to a member of public was ‘X', where the risk from ‘X' can be compared to a number of back x-rays, living in a granite area, or even smoking cigarettes. The thing is we will be able to do this ... but I still think the ‘radiation' and ‘nuclear' issues will dominate over any realistic dose assessment.

However, as a final thought at this time, I do concede that the nuclear industry will have to take a long hard think about all this. Building in a known active earthquake area? Back-up systems? Defence in depth? Diversity? Engineering substantiation? All these features are incorporated into modern nuclear plant at the design stage - there is no reason to believe that the same thing could happen to modern plant. However, I am sure that at this present time that is going to be no reassurance for many living near older plant.

12/3/2011 - Effect to the Nuclear Facilities from the earthquake on east area of Japan

I normally start these blog entries, which deal with IAEA reports, by directly displaying the report. However, in this case I must emphasise that the shear terrible devastation in Japan - the obvious loss of life, structure, amenity, houses, family, friends etc etc - makes the nuclear issues (in my view) pale into insignificance. Such nuclear matters as noted below are not ‘insignificant' of course, far from it, but when compared to the current disaster they must be seen in context. Unfortunately, the media do not see this at all.

This is taken from the IAEA event log.

Effect to the Nuclear Facilities from the earthquake on east area of Japan



March 11, an earthquake hit east area of Japan. Summary of earthquake and current status of each nuclear facility is as follows;

1. Summary of Earthquake

(1) Time of Occurrence: 14:46 (UTC 5:46) March 11, 2011, Friday
(2) Epicenter: Off-Coast of Sanriku (North Latitude: 38; East Longitude: 142.9), 10km deep, M8.8

2. The status of operation at Power Stations (Number of automatic shutdown(units): 10 (as of 00:30(UTC:11:46), March12)

a. Onagawa Nuclear Power Station (Onagawa-machi and Ishinomaki-shi, Miyagi Prefecture)

(1) The status of operation
Unit 1 (524MWe): automatic shutdown
Unit 2 (825MWe): automatic shutdown
Unit 3 (825MWe): automatic shutdown

(2) Readings of monitoring post etc.
Variation in the monitoring post readings: No
Variation in the main stack monitor readings: No

(3) Report concerning other malfunction

Report of fire: CO2 extinguishment started at 17:15

b. Fukushima Dai-ichi Nuclear Power Station, Tokyo Electric Power Co.,Inc.(TEPCO) (Okuma-machi and Futaba-machi, Futaba-gun, Fukushima Prefecture )

(1) The status of operation
Unit 1 (460MWe): automatic shutdown
Unit 2 (784MWe): automatic shutdown
Unit 3 (784MWe): automatic shutdown
Unit 4(784MW): in periodic inspection outage
Unit 5(784MW): in periodic inspection outage
Unit 6(1,100MW): in periodic inspection outage

(2) Readings at monitoring post etc.
Variation in the monitoring post readings: No
Variation in the main stack monitoring readings: No

(3) Report concerning other malfunction
Article 10* of Act on Special Measures Concerning Nuclear Emergency Preparedness (Fukushima Dai-ichi, Unit 3)
(*A heightened alert condition)
Article 15** of Act on Special Measures Concerning Nuclear Emergency Preparedness (Fukushima Dai-ichi, Units 1 and 2)
(** Nuclear emergency situation)

Situation of power source to recover water injection function at the Station.
Three or four electric power source cars are waiting in the premise. Part of cable was obtained and connecting work is under way. This work is done with paying attention to tsunami. (2:00, March 12)

Pressure in the Confinement Vessel has arisen. The pressure could have arisen to 600kPa as compared to the design pressure of 400kPa.

c. Fukushima-Daini Nuclear Power Station(TEPCO)
(Naraha-cho/Tomioka-cho, Futaba-gun, Fukushima pref.)

(1) The status of operation
Unit1(1,100MW): automatic shutdown
Unit2(1,100MW): automatic shutdown
Unit3(1,100MW): automatic shutdown
Unit4(1,100MW): automatic shutdown

(2) Readings at monitoring post etc.
Variation in the monitoring post readings: No
Variation in the main stack monitoring readings: No

(3) Report concerning other malfunction
Report of fire: No
Article 10* of Act on Special Measures Concerning Nuclear Emergency Preparedness (Fukushima Dai-ni, Units 1,2 and 4)
(*A heightened alert condition)

The incident log for the above event can be read at the following link: IAEA News (You may need to log in as a guest).

Ionactive Comment

This report was sent at 2011-03-12 00:41:00 UTC. You will note there is no INES rating at this time - it is too early to make that assessment. Further entries to the events database will no doubt be made once more facts are available.

Facts - something we all sometimes have a problem dealing with (myself included). The problem is, when little or no facts are available, we make assumptions. The media then use experts (who may or may not have an agenda either for or against nuclear issues) to then make statements based on those assumptions (which may of course be an assumption of an assumption) - that makes is assumptions2.

The media then begins to use words like ‘melt down' (or meltdown) - this term is not even recognised by the IAEA! A loss of coolant accident would be a more appropriate phase, but it does not have the same level of media spin does it?

Will add more stuff or comment as the ‘facts' become available.

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About Our Blog

This is the company blog of Ionactive Consulting Limited, a Radiation Protection Adviser consultancy. Visit here often to read our views on radiation protection and related matters. You can contact our director and RPA directly at

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