To link to the BBC Science & Environment Page please Click here

UK's atomic clock 'is world's most accurate'

By Jason Palmer Science and technology reporter, BBC News, Teddington

An atomic clock at the UK's National Physical Laboratory (NPL) has the best long-term accuracy of any in the world, research has found.

Studies of the clock's performance, to be published in the journal Metrologia, show it is nearly twice as accurate as previously thought.

The clock would lose or gain less than a second in some 138 million years.

The UK is among the handful of nations providing a "standard second" that keeps the world on time.

However, the international race for higher accuracy is always on, meaning the record may not stand for long.

The NPL's CsF2 clock is a "caesium fountain" atomic clock, in which the "ticking" is provided by the measurement of the energy required to change a property of caesium atoms known as "spin".

By international definition, it is the electromagnetic waves required to accomplish this "spin flip" that are measured; when 9,192,631,770 peaks and troughs of these waves go by, one standard second passes.

Matching colours

Inside the clock, caesium atoms are gathered into bunches of 100 million or so, and passed through a cavity where they are exposed to these electromagnetic waves.

The colour, or frequency, is adjusted until the spins are seen to flip - then the researchers know the waves are at the right frequency to define the second.

The NPL-CsF2 clock provides an "atomic pendulum" against which the UK's and the world's clocks can be compared, ensuring they are all ticking at the same time.

That correction is done at the International Bureau of Weights and Measures (BIPM) in the outskirts of Paris, which collates definitions of seconds from six "primary frequency standards" - CsF2 in the UK, two in France, and one each in the US, Germany and Japan.

For those six high-precision atomic pendulums, absolute accuracy is a tireless pursuit.

At the last count in 2010, the UK's atomic clock was on a par with the best of them in terms of long-term accuracy: to about one part in 2,500,000,000,000,000.

But the measurements carried out by the NPL's Krzysztof Szymaniec and colleagues at Pennsylvania State University in the US have nearly doubled the accuracy.

The second's strictest definition requires that the measurements are made in conditions that Dr Szymaniec said were impossible actually to achieve in the laboratory.

"The frequency we measure is not necessarily the one prescribed by the definition of a second, which requires that all the external fields and 'perturbations' would be removed," he explained to BBC News.

"In many cases we can't remove these perturbations; but we can measure them precisely, we can assess them, and introduce corrections for them."

The team's latest work addressed the errors in the measurement brought about by the "microwave cavity" that the atoms pass through (the waves used to flip spins are not so far in frequency from the ones that flip water molecules in food, heating them in a microwave oven).

A fuller understanding of how the waves are distributed within it boosted the measurement's accuracy, as did a more detailed treatment of what happens to the measurement when the millions of caesium atoms collide.

Without touching a thing, the team boosted the known accuracy of the machine to one part in 4,300,000,000,000,000.

But as Dr Szymaniec said, the achievement is not just about international bragging rights; better standards lead to better technology.

"Nowadays definitions for electrical units are based on accurate frequency measurements, so it's vital for the UK as an economy to maintain a set of standards, a set of procedures, that underpin technical development," he said.

"The fact that we can develop the most accurate standard has quite measurable economic implications."

 

 

 

 

The Incident at the FUKUSHIMA Nuclear PLANT - March 2011

N. Keith Tovey MA, PhD, CEng, MICE, CEnv

Reader Emeritus in Environmental Sciences

Norwich Business School

University of East Anglia

NORWICH

NR4 7TJ

The first part of these notes were written by 18:30 on 12

 

th March 2011. Subsequent updates follow as shown below:

? 17:00 on 13

 

 

th March – section 9.

? 23;00 on 15

 

 

th March – section 10.

For clarity and ease of identifying updates, each update is written in a different colour.

 

1. Background

During my lectures on Nuclear Power a month ago, there were some types of nuclear reactor which I did not cover this year as I had less time than previously. I pragmatically decided not to cover the Boiling Water reactor – a derivative of the Pressurised Water reactor as this type has never been built in the UK, and neither are there plans to at the present time. Despite this I did include a few supporting summary notes from last year.

However, in view of the Fukushima incident it is perhaps relevant to summarise what it would appear has been happening. Indeed there has been much incorrect information put out by the media. Thus they referred to "flying in coolant". Why on earth would any one do this when the coolant they are referring to is ordinary water. What they may have meant was equipment to assist with cooling which is something very different altogether.

Information is still incomplete, but this is my analysis for information I have obtained to date. It is a fast moving story and things may change – but the following is the situation as of 18:30 on 12

 

th March 2011.

A Boiling Water Reactor. Notice that the primary circuit steam which may become radioactive in normal operation is passed directly to the turbines.

2. A basic introduction to the BWR

Unlike a Pressurised water reactor, a Boiling Water Reactor actually allows the water in the primary cooling (i.e. reactor cooling circuit) to boil and as a result operates at a pressure of around 70 bar rather than around 160 bar in a normal PWR. However, there are major differences.

BWRs are the second most common reactor in the world although in Japan it is the most common reactor with 30 units in operation as opposed to 17 PWRs (see table below)

Thus unlike in a PWR, the primary coolant passes directly through the turbines rather than relying on heat exchangers to raise steam for the secondary turbine circuit. As a result the BWR has the potential of being a little more efficient thermodynamically than a PWR.

In all nuclear power plants there is the possibility of a burst fuel can – usually no more than a small pin prick which may allow gaseous and/or liquid daughter products from the nuclear reaction to circulate in the primary circuit. In the case of the British Design (MAGNOX and Advanced Gas Cooled reactors) and the Canadian design (CANDU), such defective fuel elements can be removed while the reactor is still on line and generally any contamination within the primary coolant is very minimal.

In the case of the PWR and BWR reactors, however, refuelling can only be done at routine maintenance shutdown – typically up to 21months apart, and so the primary coolant will tend to become radioactive from any fuel cladding issues. In the case of the PWR, such mildly radioactive cooling water is kept within the containment building and the water passing through the turbines is not radioactive. In the case of a BWR as at Fukushima-Daiichi-1 the slightly radioactive cooling water will pass through as steam through the turbines such that the turbine hall may be an area of slightly raised radiation levels.

3. Fukushima Nuclear Power Plants

At Fukushima there are ten separate reactors in two groups making it one of the highest concentration of nuclear plant in the world. The Daiichi group has six separate reactors which were commissioned between March 1971 and April 1979 whereas the Daini group located some kilometres to the north has four commissioned between 1981 and 1986. The affected plant was Fukushima-Daiichi-1 which is the oldest and scheduled to reach 40 years of operation later this month. This reactor is the third oldest reactor still operating in Japan and would have been scheduled to close shortly. It has a gross capacity of 460 MW and a net output of 439 MW (i.e. after power has been taken for pumps etc). Most of the other reactors are larger at 760MW each for Daiichi -2 to 5 and 1067MW for the other five reactors.

The performance of Daiichi-1 has been fairly poor with an average annual load factor of just 53% compared with several at the Daini complex at well over 70% and Sizewell B with a load factor of 86%

4. Control of Nuclear Reactors and shut down phase 1

In many reactors the neutron absorbing control rods are held by electro-magnets and in the event of an incident (or power failure) will automatically fall by gravity. In the case of many BWRs and particularly the early ones, the control rods are driven up into the reactor and this will take typically around 5 – 7 seconds to complete. The attached table demonstrates that while some reactors continued throughout the quake, many shut down automatically as they were intended to do and this part of the phase was completed successfully.

You will remember from the lectures that it is quite difficult to sustain a nuclear reaction within the core and sufficient neutron density is required and also these must be of the slow moving neutron type for which moderators are needed. The purpose of the control rods is to absorb neutrons and thus shut down the reaction. Thus all the affected reactors shut down automatically as planned.

 

5. Aspects of the Incident – the early stages.

The second part of the incident is also something which I only covered briefly and that was the issue of radioactive decay. While it is clear that in all the 11 reactors which shut down automatically as soon as the earthquake hit, it is important to remember that this radioactive decay process still emits heat typically around 5 – 8% of the full output power during the first 24 hours falling to around 1% after a week and declining further thereafter. Thus it is critical that the cooling water circuits continue for several days to remove this residual heat.

 

In a MAGNOX reactor the heat output during operation is around 1 MW per cubic metre – which would be the equivalent of boiling a litre of water with a 1 kW element in the kettle. The analogy would continue that if the kettle switched off when the water boils the heat loss would be such that the kettle would loose heat and as long as the element remains covered, no problem would arise. However, imagine that the electricity does not turn off completely but still continues at say 10% (i.e. 100 W), this would be more than sufficient to keep the water boiling and if the water level was not continually topped up as the water boiled then the element would be exposed and fail. This is what effectively happens when a nuclear station is shut down so cooling is critical

 

In a boiling water reactor, the power density is nearly 100 times that of a MAGNOX reactor so in normal operation the heat generation is 100 times as will also be the decay heat generation, and at 10 kW (in the case of the kettle analogy) still generated after shutdown this potentially could cause the element to melt.

 

Notice this condition is much more critical in PWR and BWR plant compared to the British gas cooled reactors (MAGNOX and AGR).

In the case of FUKUSHIMA-DAIICHI-1, as with all similar situations which may occur with a turbine trip, pumps will automatically cut in to keep the cooling water circulating. However, with the simultaneous shutdown of 11 separate plant simultaneously and also a similar capacity of normal fossil fuel power stations, there was a substantial loss of power across Japan meaning there was insufficient power available to be drawn for cooling not only for this reactor but for all other 10 reactors which tripped simultaneously.

 

There are emergency procedures which then automatically cut in by drawing power (if necessary from batteries) until diesel or gas generators cut in to provide local emergency power. It would appear that such generators did indeed cut in and provided power for at least 20 minutes – some reports say 1 hour, but then some of these failed – either because they were knocked out by the tsunami, or the necessary distribution was so affected by the tsunami.

 

As it appears that the emergency core cooling failed as least in part if not in full, the temperature of the water/steam in the pressure vessel will rise and if this continues more water will convert to steam which occupies 1700 times the volume causing an increase in pressure in the circuit. Pressure vessels will be designed to withstand pressures at least 50% above normal operation and may be 100% or more above, so a small rise is of no consequence, but it this does continue to rise, then it is important that this pressure is released and it is probable, although this needs to be confirmed, that steam (remember this is radioactive because of the design of BWR) will be released into the containment building. This is planned in such an emergency and is not, by itself a serious consequence. In some BWR, there is a condensate suppression pool at the bottom as shown and this will tend to condense some of the steam now in the containment building.

 

Remember that in PWRs and BWRs small changes in volume accompanying changes in temperature can lead to significant changes in pressure – whereas in the gas cooled reactors the changes in pressure with changes in volume / temperature are less marked.

 

6. Reports of fires at power stations

In the early hours of the disaster there were reports of fires at power stations, but information was sketchy and it was not clear whether this referred to fires in the turbine hall as does happen in fossil fuelled power stations – e.g. a few years ago Tilbury coal fired station was so affected. Within a turbo generator, hydrogen is used for cooling the generator as it is a particularly good conductor of heat. A hydrogen leak here could start a fire and/or an explosion. Whether this was the cause of the explosion is not known.

Hydrogen build up

If hot steam is released and it comes into contact with some hot surfaces, the steam can split into hydrogen and oxygen. This hydrogen could be the cause of an explosion as it was at the Three Mile Island incident where there was an explosion which, despite the core becoming uncovered was entirely contained within the containment building.

 

In most PWR and BWR nuclear power stations the containment building is dome shaped as this will withstand much higher pressures in the event of an explosion. Indeed Sizewell B has two independent domes. However, at Fukushima, the building appears to be cuboid, and it is not clear whether the containment building was within the building which failed and remained intact, and the actual building seen to fail being a shell covering the large space needed for cranes etc or whether it was the containment building itself which seems odd from its shape.

 

7. What then happened?

There indeed was an explosion as was seen from TV pictures, and this is likely to have been a hydrogen explosion. There is the possibility it could have been a structural collapse as a delayed effect of the earthquake – remember the twin towers in New York stood for some time after the terrorist attack in 2001 before they collapsed. However, the pictures as far as I could seen did suggest a small flame which would make hydrogen more likely. Once again this by itself – which ever is the case - is not overly serious and there were reports immediately afterwards that radiation levels were falling.

 

However, what is critical is the integrity of the pressure vessel. Later reports suggested that this was intact, and if this is so then the situation is likely to be recoverable, albeit with the reactor deemed a write off, but since it was almost at the end of its life (probably within next 12 months anyway) this would not have much of a financial impact.

 

If the pressure vessel integrity is compromised, and that is far from clear as I write at 18:25 on 12

 

th March, then that is more serious, and there may be a melting of the fuel, but there can then be no nuclear explosion as the fuel is at far to low an enrichment and the moderator has been lost anyway. However. At 18:20 the World Health organisation said "the public health risk from Japan's radiation leak appears to be "probably quite low". This suggests that the vessel is still intact:

 

Care must be taken on how subsequent cooling is attempted as if water is used and it contacts with very hot fuel cladding (Zirconium), then more hydrogen could be produced leading to a further chemical explosion which might lead to a further leak of contamination.

Do remember that radiation is generally of little consequence, but contamination is something over which we should be concerned.

 

8. Consequence of Earthquake on UK energy

With 11 reactors in total tripped, it will take some time to bring them all back on line and Tokyo Electric Power Company TEPCO is planning to run its fossil fuel plant more than normal which will mean an increase demand for oil and gas (Japan has limited coal generation).

Already there are moves in the financial markets seeing oil prices likely to rise as demand rises at the same time as the Middle East problems. Russia has already been approached by Japan for more LNG shipments at a time when LNG shipment prices are also rising, and since the UK is increasing dependent on energy imports this could see significant price rises in wholesale electricity prices in the UK in the near future.

 

9. Update on 13

 

th March 17:00

Consultation of various further information and including the IAEA – Webpage over thye last 18 hours allows an update.

9.1. Cause of Hydrogen Build up in Fukushima – Daiichi 1 reactor.

The most probable cause of this is not a hydrogen leak in the turbine hall which may have caused a fire in the turbine hall elsewhere, but as a result of the pressure venting from the reactor vessel. It would appear that the top of the fuel elements and or systems above in the reactor vessel came uncovered and this hot metal, particularly if it were the fuel cladding zirconium would have reacted to split the steam. This by itself is of little consequence.

However, the build up of hydrogen within the cuboid building was something that could ultimately result in an explosion as indeed happened. The alternative would have been to have regularly releasing the hydrogen and steam from the building minimising the build up.

When the explosion occurred – reports were of a massive or huge explosion, but I have rerun the video several times, and it can only be classed as small to moderated, and what appeared to be dramatic was the simultaneous steam release and the debris from the collapsing building. [Remember the very very large plumes of smoke and dust when the twin towers collapsed in 2001 – this was very very minor in comparison]. That it was a small explosion is confirmed by the higher detail images of Daiichi -1 available today showing the reinforcement steel intact and undistorted. Had the explosion been large then this steel would either have disappeared or been bent outwards, neither of which appear to be the case.

9.2. The integrity of the Pressure Vessel

The explosion clear took place around the pressure vessel and the fact that the cuboid shell gave way probably helped to avoid damage to the pressure vessel itself. All evidence indicates that this is the case - the very short burst of radiation which then fell, and the very limited amount of contamination on the population.

The News reports are confusing in references to radiation and contamination. Radiation decays rapidly with distance and even a short distance away from the plant such as 1 km direct line of sight would be adequate to attenuate the level to safe level even in the most intense situation. One can walk away from radiation, and if one is irradiated such as when having an x-ray it stops immediately the source is switched off or the person moves out of the critical area. Contamination on the other hand is another matter, as dust particles which might be radioactive will continue to irradiate a person unless the contamination is removed. Thus stripping off clothing with contamination is all that is needed to protect a person from health effects

 

unless the contaminated particle is either ingested or breathed into the lungs. It is for this reason that larger exclusion zones than required to limit impacts of radiation are set up.

9.3. Critical Unanswered Questions

The nuclear plants all shut down safely or continued operating normally immediately after the earthquake, despite the fact that in the BWR the control rods have to be driven up rather than falling gravity in most designs. The standby by generators appears to have started when the grid electricity supply failed as they should [although this still needs to be confirmed], and some reports suggest that they ran for 20 minutes – others for up to an hour before failure. However, was this failure to continue cooling:

1. a failure of the generators .

 

2. the generators being affected by the tsunami, bearing in mind the station is close to the coast,

3. a failure in the water supply as there are severe water shortages reported in the area.

Of these three, the first seems unlikely as there is now a second and possibly third plant at the Daiichi complex now suffering similar problems and it is improbable that all back-up generators (and there are typically at least 4) failing at all the plants.

Since all the plants are parallel to the coast, then option (2) is possible, but why then contemplate using seawater as ordinary water would be far less corrosive of the plant. The strong likelihood is that (3) is the primary cause, although option (2) may also have figured as a partial cause.

9.4. Fukushima-Daiichi-1 present situation

All evidence points to the main pressure vessel being intact and cooling with sea water is now (16:00 13

 

th March) is being pumped in to keep the core covered, In addition boron is added to this water as this is a neutron absorber assist further.

Using sea water is an odd solution as one would normally use ordinary water and the use of sea water does seem to reinforce the issue of option (3) being the primary cause of cooling failure. Using sea water, which is corrosive would make the plant unusable ever again

The Fukushima-Daiichi-1 plant is within 2 weeks of being 40 years old and was due to close shortly (within next 12 months or so) and so the decision to use sea water will have limited consequences on the future of the plant.

 

9.5 Other incidents. 17:00 March 31th

The situation is somewhat confused with different agencies, e.g. BBC, IAEA, Bloomberg Press etc, reporting different things. However, what does seem consistent is that

Fukushima-Daiichi-3

1. There appears to have been a similar loss of coolant at Fukushima-Daiichi-3 reactor close to the one previously causing concern. This is a larger reactor with a gross capacity of 784 MW and a net capacity of 760MW. Once again steam has been released from the pressure vessel and this probably may contain hydrogen again. With the experience of Reactor 1, the operators may try to release the build up of gas from the cuboid building to minimise the risk of an explosion, but this will almost certainly cause the release of some

small amounts radioactivity and/or contamination.

Remember that as BWR’s and PWR’s cannot replace defective fuel elements during operation, the primary cooling water circuit will almost certainly have contained some radioactivity/contamination before the incident started – unlike the situation in a MAGNOX, AGR, or CANDU reactor.

2. This reactor is 37 years old this year and the decision to use sea water as a last resort would only shorten its life bay a few years.

3. There are reports that this reactor is fuelled with mixed oxide fuel (MOX) which is a mixture of Uranium oxide (4-5% enrichment) with some plutonium which has been obtained either from reprocessing or from decommissioned nuclear weapons.

4. It is not clear what effect this mixed oxide fuel would have in a worst case scenario where the pressure vessel was ruptured. The primary source of contamination would be from the daughter products from the nuclear reactions, and the radiation issues arising from any plutonium would normally be relatively small compared to these. On the other hand there may be more significant chemical hazards.

5. There are reports of a possible faulty valve and or gauge, but the full significance of this cannot be assessed without more information.

Fukushima-Daiichi-2

1. This reactor is located between the number 1 and number 2 reactors and it is reported (16:00 on 13

 

th March) that sea water is also being pumped into the core here which means that this reactor will never be used again.. This reactor appears to be identical with reactor 3 , but it is not clear whether MOX fuel is being used. This reactor will be 38 years old later this year.

Fukushima-Daiichi 4,5 and 6

These reactors were under going routine maintenance and refuelling at the time of the earthquake and are thus unaffected.

Fukushima –Daini 1,2,3 & 4

1. The situation at the site is confused with several corrections to statements being made. The latest information suggested that all four units 1 - 4 shut down automatically and that

 

unit 3 is now in a safe cold shutdown state, whereas units 1,2, and 4 are still grid connected.

2. There are reports of a worker being killed and possibly some injured, but this appears to be associated with a normal industrial accident associated with the operation of a crane. One comment I saw suggested that that the operator fell while mounting the crane at the time the earthquake hit and in which case is total unrelated to the operation of the power plant.

Onagawa 1, 2, & 3

1. There are reports of slightly increased radiation levels around one of these reactors, but IAEA state (13:35 on 13

 

th March) that all reactors are under control. Onagawa No 3 reactor is only 10 years old this year

Clearly the overall situation is changing rapidly as more information is becoming available, but the above update was finished at 17:00 on 13

 

 

th March. If there are any further developments a further update will be written.

=======================================

 

10. Updates: 15

th March 2011

10.1 General coverage

The situation has indeed been very fast moving, and one must commend the Japanese authorities on the frequent updates in what must be a difficult situation. However, confusion still rains in the media, and there has been perhaps an over concentration on the nuclear issues when equally important issues have received little or no attention. I originally missed the images of the fires and explosions ranging out of control at the petro-chemical works/ oil refineries show on Friday evening. Apart from these initial pictures there has been limited reference.

The explosions and fires were clearly on a much larger scale than the nuclear explosions and quite probably there were workers killed or injured as the incident occurred during the working day. However, unlike the nuclear incident we are hearing next to no information. One BBC report did say that standing 2-3 miles away from one such plant that the smoke was acrid suggesting at least some toxic chemicals some may well have been carcinogenic. Is it that the fixation on the nuclear issues, serious as they may be, may be diverting attention away from a more serious issue to health? Remember one can readily detect radiation and radioactive contamination at very very low level, far more easily than concentration of chemicals which could be hazardous to health.

10.2 Update on impact on UK gas supplies

[See section 8 above].

According to Reuters, and as predicted wholesale LNG gas prices to the UK had risen 10% by 19:00 this evening [15

 

th March] since the earthquake last Friday. This combined with the situation in the Middle East will see a further upward rise in retail prices as 25%+ of the UK gas supply now comes from LNG.

10.3 Distorted Information in the media.

There will be an urgent review of plans for new nuclear plants, but a review of the safety issues on existing plant needs to be assessed. In many respects the Fukushima plants behaved very well to the earthquake despite their near 40 years of age, but it was the tsunami which I speculated might be the fundamental issue does seen to have been the main cause. I understand that the coastal units at Fukushima-Daiichi were designed to withstand a 6.5m tsunami, which as we now know was significantly overtopped at 9 – 10m – however, more about that later.

There are arguments against nuclear power which can be expounded and a reasoned and rational debate is required as we decide whether or not nuclear power should form part of a future electricity generating mix. However, many statements in last few days on blogs demonstrate a complete naiivity on the part of the writers. In some cases such articles are published in the media, and it is surprising that such comment are published without at least questioning the facts and reasoning behind the statements.

Thus on page 6 of the

 

Opinion and Debate Section in the Independent Newspaper today (15th March), Terry Duncan writes:

"I recall in my youth, more than 60 years ago, the hydro-power stations being built all over my native Highlands – they are still operating today.

Why can this proved system of generating electricity not be used nationwide.?

In some areas water to turn the turbines could be pumped and returned to the sea. Modern non corrosive materials could be used for the pumps and pipes making maintenance reasonably trouble free.

The we would have no fears of nuclear accidents, at dated plants, in a country which does experience earthquakes, although at present ,infrequent"

Terry Duncan demonstrates his ignorance, by

 

a) Not considering the accidents occurring in earthquakes from dam failures - e.g. the Malpasset Dam near Frejus burst in 1959 killing over 500 people immediately.

b) Where does he expect the power to come from to pump the water. We already have pumped storage schemes to provide a limited amount of storage capacity, but as everyone knows only around 80% of energy is recovered later in generation so it consumes far more energy than it comes.

Where does Mr Duncan believe the power will come from? What is the point of pumping water around wasting energy unnecessarily when we should be saving it?.

There have been issues reported at three different complexes see section 9.5 above. The current situation (23:00 on 15

 

th March) appears as

10.4 Situation at Onagawa and Fulushima-Daini

10.4.1 Onagawa 1, 2 & 3

All units at this site shut down correctly and went into automatic cooling and are now sufficiently cool that sufficient of the heat arising in the initial hours after shut down had dissipated (see section 5 for a description of the decay heat cooling requirements). It would appear that the decay heat has now fallen sufficiently so to be no longer an issue. Increased radiation levels were detected at this plant, but evidence now suggests that this is arose from the contamination cloud from Fukushima-Daiichi 1 explosion on Saturday morning. Radiation levels at the plant now appear to have fallen significantly..

10.4.2 Fukushima-Daini 1,2,3 & 4

It appears that these four reactors responded differently.

Reactor 3

 

 

units 1 and 2 with the reactors reaching cool condition at 01:24 and 03:52 on 14th March respectively. There had been some concern that water in the suppression pool in unit 1 had risen high, but that has now subsided.

Reactor 4

 

 

th March) that as soon as the last reactor was cool the exclusion zone would be lifted. However, it is unlikely that this has been as Daini is south of Daiichi and the exclusion zone partly overlaps with the exclusion zone around the Fukushima Daiichi complex.

10.4.3 Fukushima Daiichi

This is the complex with the most serious incidents. There are 6 reactors: units 4, 5, and 6 were not operating at the time of the earthquake but were under refuelling and/or maintenance. All other reactors went through initial shutdown correctly as explained in section 5.

Daiichi Unit 4

A fire broke out in unit 4 cooling pond for spent fuel elements. This was not in the reactor building, but in the holding area where, as a result of the refuelling then under way may have included a significant inventory of the reactor fuel – some of which would be held in the pond before shipping for reprocessing or disposal. However, as noted later, the fire was NOT in the cooling pond.

This cooling pond is like a very deep swimming pool typically 10m or more in depth. The spent fuel is stored at the bottom and there is sufficient depth of water (5m or more) which acts as the biological screen for radiation so above the pool radiation levels are at a safe level. What is a worry was the report in the media of a fire in the pool which would suggest that some of the water had evaporated. That is odd as the volume of water is so large that it would take probably weeks to get to a really serious state. However, if that were to happen then this potentially could be much more serious than the incidents in 1, 2 and 3. If it became dry, then any burst fuel cans could release significant quantities of radio active nuclides. Some of these, Xenon etc have very short half lives and in matters of hours they have decayed to stable isotopes.

Iodine is more problematic as it has a half life of around 9 days, but by 90 days it will have decayed to 1/1000

 

th of the original concentration, by 6 months to less than 1 millionth and in a year 1 trillionth. Supplying people in the immediate vicinity with non radioactive iodine minimises the take up of radioactive iodine in the thyroid gland, and can thus be managed. What is of more concern are releases of radioactive nucleides with half lives of a few years such as Strontium and Caesium an decay very little over the lifespan of a human.

Any radioactive nucleides with long half lives of hundreds or thousands of years are a little consequence radiologically as the radiation levels are low, often very low anyway. There is a myth that the most hazardous radioactive nucleides are those with long half lives. It is those with medium long half lives which we should be most concerned about. Those intense one with short half lives such as iodine can be managed.

The fire occurred

 

 

NOT in the cooling pond but as a result of an oil leak in one of the circulating pumps for the cooling water.

For more information on the Daiichi cooling ponds see

http://resources.nei.org/documents/japan/Used_Fuel_Pools_Key_Facts.pdf

 

Daiichi 5 and 6

Like Daiichi 4, these reactors were not operating and were already shut down before the earthquake hit. There are reports of temperature rises in the cooling ponds for the spent rods, and this might imply a failure of the circulating pumps for the cooling ponds. Through radioactive decay, heat is still emitted from spent fuel for several months, albeit at increasingly lower rates as time progresses. The cooling pumps circulate the water in the cooling ponds in a closed loop through chillers to remove any heat.

It is not known whether in the Japanese cooling ponds the water is also circulated through clinoptilolite a material which absorbs any radioactive particles which might migrate to the cooling pond water from a burst fuel can.

Daiichi 1

A small explosion in the reactor building, but not the containment took place on the morning of the 12

 

th March as noted in section 7. The fact that radiation levels around this reactor have fallen does support the diagnosis that the containment structure is largely intact. Sea water continues to be pumped in to maintain cooling although there are reports that the tops of some of the fuel elements may have been exposed. This would allow the zircaloy cladding of the fuel elements which is designed to retain the radioactive daughter products to become defective and release products. Equally, any steam in contact with hot zircaloy will partly split to hydrogen and oxygen which after pressure release to the outer containment building would bet he source of a potential hydrogen explosion as did happen and this would take any volatile radioactive daughter products away as indeed happened. Please read the commentary about the cooling ponds at Daiichi 4 to understand the consequences of such a release.

As long as such cooling continues the reactor should be brought to a stable condition. The core is almost certainly damaged, but the containment is still intact.

Information indicates that the reactor was due to close at the end of this month after 40 years of operation confirming my speculation in section , so the fact that sea water will have damage the core is of little consequence except that it will make the decommissioning more difficult.

The used of borated water (boric acid) is often mentioned. This is used in PWR and BWR’s as a means of control as borated water strongly absorbs neutrons and will ensure that no further chain reactions take place.

Cooling of the core and containment vessel is continuing

 

Daiichi – 3

An explosion similar to Daiichi 1 took place in the reactor 3 containment building at 11:01 local time yesterday (14

 

th March). This was larger than that of unit 1 but once again the main containment of the core is largely intact although there may be some damage, and the sequence of events leading up to this was similar to that for unit 1. The was evidence of over-pressure within the containment structure but this fell. There was a short surge in radiation to around 50 microSieverts per hour for a relatively short time falling quickly to 10 – 20 microSieverts per hour and in 90 minutes to 4 microSieverts per hour. 10 km distant at the Daini plant – no change in radiation was detected indication there was no contamination reaching the Daini site.

However, another source put the instantaneous radiation at 3000 microSieverts falling to around 200 microSieverts by 12:30. It is probable that this discrepancy comes from different locations of measurement and some may refer to other buildings on the site.

To put this in context the maximum does received by anyone at the Three Mile Island incident in 1979 according to Wikipaedia was 1000 microSieverts (1 milliSievert) with the average for people living within 16 km (80 microSieverts). 1 microSievert is the does one can expect from eating 10 bananas, whereas an Xray could subject the patient to up to 14000 microSieverts. In some places in the world the annual background radiation is as high as 50000 microSieverts per year.

Cooling of the core with seawater continues but it is not clear whether the containment is also being doused with sea water

 

Daiichi 2

This reactor had an explosion in the early hours of 15

 

th March (JST). This seems to have been more serious and caused damage to the core suppression pool. However, the damage to the external building is less than for units 1 and 3.

As with 1 and 3, core cooling with sea water continues.

10.5 General Comments

Clearly the situation is changing rapidly and apart from this documentation which I started on 12

 

 

th March other website have appeared who clearly have more time than I do and the reader should also consult these following links. How long I shall continue to update the information does depend on the time I have which is getting more and more limited over next few days. In the meantime: also consult:

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Initial summary 13th March

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Update on 14th March

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further technical information

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Update on 15th March

STATUS of NUCLEAR REACTORS in JAPAN following Earthquake on March 11   th 2011. Capacity (MWe)

Date

Name

Type

Status

Location

Net

Gross

Connected

FUKUSHIMA-DAIICHI-1

BWR

Operational

FUKUSHIMA-KEN

439

460

1970/11/17

Automatic Shutdown

FUKUSHIMA-DAIICHI-2

BWR

Operational

FUKUSHIMA-KEN

760

784

1973/12/24

Automatic Shutdown

FUKUSHIMA-DAIICHI-3

BWR

Operational

FUKUSHIMA-KEN

760

784

1974/10/26

Automatic Shutdown

FUKUSHIMA-DAIICHI-4

BWR

Operational

FUKUSHIMA-KEN

760

784

1978/02/24

Under Maintenance

FUKUSHIMA-DAIICHI-5

BWR

Operational

FUKUSHIMA-KEN

760

784

1977/09/22

Under Maintenance

FUKUSHIMA-DAIICHI-6

BWR

Operational

FUKUSHIMA-KEN

1067

1100

1979/05/04

Under Maintenance

FUKUSHIMA-DAINI-1

BWR

Operational

FUKUSHIMA-KEN

1067

1100

1981/07/31

Automatic Shutdown

FUKUSHIMA-DAINI-2

BWR

Operational

FUKUSHIMA-KEN

1067

1100

1983/06/23

Automatic Shutdown

FUKUSHIMA-DAINI-3

BWR

Operational

FUKUSHIMA-KEN

1067

1100

1984/12/14

Automatic Shutdown

FUKUSHIMA-DAINI-4

BWR

Operational

FUKUSHIMA-KEN

1067

1100

1986/12/17

Automatic Shutdown

HAMAOKA-1

BWR

Permanent Shutdown

SHIZUOKA-PREFECTURE

515

540

1974/08/13

HAMAOKA-2

BWR

Permanent Shutdown

SHIZUOKA-PREFECTURE

806

840

1978/05/04

HAMAOKA-3

BWR

Operational

SHIZUOKA-PREFECTURE

1056

1100

1987/01/20

Under maintenance

HAMAOKA-4

BWR

Operational

SHIZUOKA-PREFECTURE

1092

1137

1993/01/27

Continued operation

HAMAOKA-5

BWR

Operational

SHIZUOKA-PREFECTURE

1212

1267

2004/04/26

Continued operation

HIGASHI DORI 1 (TOHOKU)

BWR

Operational

Aomori Prefecture

1067

1100

2005/03/09

Under maintenance

JPDR

BWR

Permanent Shutdown

IBARAKI

12

13

1963/10/26

KASHIWAZAKI KARIWA-1

BWR

Operational

NIIGATA-KEN

1067

1100

1985/02/13

Continued in operation

KASHIWAZAKI KARIWA-2

BWR

Operational

NIIGATA-KEN

1067

1100

1990/02/08

Not operating at time

KASHIWAZAKI KARIWA-3

BWR

Operational

NIIGATA-KEN

1067

1100

1992/12/08

Not operating at time

KASHIWAZAKI KARIWA-4

BWR

Operational

NIIGATA-KEN

1067

1100

1993/12/21

Not operating at time

KASHIWAZAKI KARIWA-5

BWR

Operational

NIIGATA-KEN

1067

1100

1989/09/12

Continued in operation

KASHIWAZAKI KARIWA-6

BWR

Operational

NIIGATA-KEN

1315

1356

1996/01/29

Continued in operation

KASHIWAZAKI KARIWA-7

BWR

Operational

NIIGATA-KEN

1315

1356

1996/12/17

Continued in operation

OHMA

BWR

Under Construction

AOMORI

1325

1383

ONAGAWA-1

BWR

Operational

MIYAGI PREFECTURE

498

524

1983/11/18

Automatic Shutdown

ONAGAWA-2

BWR

Operational

MIYAGI PREFECTURE

796

825

1994/12/23

Automatic Shutdown

ONAGAWA-3

BWR

Operational

MIYAGI PREFECTURE

796

825

2001/05/30

Automatic Shutdown

SHIKA-1

BWR

Operational

ISHIKAWA-KEN

505

540

1993/01/12

Tripped on 1   st March 2011 had not been restarted

SHIKA-2

BWR

Operational

ISHIKAWA-KEN

1108

1206

2005/07/04

Was shut down for routine maintenance a few hours before earthquake

SHIMANE-1

BWR

Operational

SHIMANE PREFECTURE

439

460

1973/12/02

Under maintenance

SHIMANE-2

BWR

Operational

SHIMANE PREFECTURE

789

820

1988/07/11

Continued in normal operation

SHIMANE-3

BWR

Under Construction

SHIMANE PREFECTURE

1325

1373

2011/12/15

TOKAI-2

BWR

Operational

IBARAKI-KEN

1060

1100

1978/03/13

Automatic Shutdown

was still heating on the morning of 14th March and an exclusion zone of 10 km was placed around the plant. Subsequently at 15:42 cooling began and by the evening of 15th the reactor was now cool.

TEPCO and the Government did say (on 14

 

went through the planned cooling phase as was sufficiently cool 34 hours after the incident.

The immediate first stage emergency core cooling systems failed on all three units causing temperatures within the core to rise with the possibility that a pressure release into the outer containment might have been necessary. However, back up secondary systems were brought into play at

 

 

 

 

 

 

 

 

 

 

Cancer spread mechanism probed

We will soon have a “cure for most cancers”, the Daily Express has reported. The newspaper claims that scientists are close to providing the "holy grail" of cancer cures, which will be available within a few years.

The scientists in question were in fact much more cautious when reporting their own research, which was a laboratory study looking at a gene called WWP2 that is present in all cells. The gene can produce a group of different proteins that in turn regulate other proteins that normally prevent tumours from spreading in different ways. The researchers hope eventually to modify this process with drugs so that they can “cure cancer”. However, this was still a very preliminary laboratory study and no such drug has yet been found. In short, such a wide-ranging cure is much further away than the headline suggests.

This carefully conducted study was complex and featured a range of tests examining the proteins and genes thought to be involved in the spread of cancers. However, it did not directly model the “spreading” of cancer cells, and further research must now test how the chemical processes identified work in real–world settings.

 

Where did the story come from?

The study was carried out by researchers from the School of Biological Sciences at the University of East Anglia. It was supported the Association for International Research, with additional funding from the Big C charity, the British Skin Foundation and the Dunhill Medical Trust. The study was published in the peer-reviewed journal, Oncogene.

Most newspapers have focused on the research’s potential for giving hope to those living with cancer, with The Daily Telegraph and BBC emphasising how the experimental study’s discoveries might improve our understanding of how cancers spread. However, this is very preliminary, basic laboratory research and although it may lead to potential drug targets in the future, it is very early days.

 

What kind of research was this?

This was a cell-culture based laboratory study that investigated a family of related proteins called “ubiquitin ligases” and how they regulate cellular processes. Of interest were one full-length protein called WWP2-FL and two other, shorter forms of the protein. The function of these proteins is to interact with other target proteins and attach a chemical called ubiquitin to them. Once a target protein within a cell has been bound with ubiquitin, it signals to the cell that the protein should be removed from the cell.

Within our DNA genes is the code used by the body to produce certain proteins. Some proteins coded for by a single gene can exist in different forms, called isoforms. The researchers looked at whether isoforms of the WWP2 protein interacted in different ways depending on whether they were the full-length or shorter form.

The researchers then looked at whether the interaction between WWP2 and other proteins in the cell would affect the ability of the cells to move. This would have implications for cancer, where cells can then move to other parts of the body and form cancers in other tissues. This process is called metastasis.

 

What did the research involve?

The research involved a number of tests to look at the various pathways and processes that may be involved in the growth and spread of cancerous cells.

The researchers first analysed the DNA sequence of the WWP2 gene to predict whether it could be used to produce proteins of different length. They confirmed their predictions by measuring the length of RNA, a molecule made when a gene produces the protein that it contains information for making.

They used a technique called “immunoprecipitation” to look at which proteins bound to the WWP2 proteins. To do this they took a mixture of proteins found within cells and passed them through a column coated in WWP2 proteins. They then used antibodies to detect which proteins had bound to the WWP2 proteins. The researchers were particularly interested in a group of proteins called “Smad” so they used antibodies that would bind to Smad proteins to look at their actions. They then measured how quickly the Smad proteins were cleared from the cell in the presence of the different forms of WWP2.

Another protein called transforming growth factor beta (TGFβ) can regulate the activation of various genes, including the genes that produce for the Smad3 and Smad2 proteins. It also regulates a process called “epithelial-mesenchymal transition” (EMT), in which stationary cells are converted into cells that move, a process that has been linked to cancer cell growth and the metastasis process that is key in the spread of cancers.

The researchers also looked at whether the WWP2 proteins switched on genes and examined a cancer cell line that undergoes EMT to see whether the WWP2 proteins affected this process.

Finally they looked at what would happen if they blocked the action of the WWP2 gene using a technique called siRNA.

 

What were the basic results?

This research tested a number of complex biological pathways, providing a number of results on the individual chemical processes that may contribute to the spread of cancerous cells.

The researchers found that there were three different length proteins made from the WWP2 gene: a full-length WWP2 protein called WWP2-FL, plus two smaller proteins called WWP2-N and WWP2-C.

They found that Smad 2, 3 and 7 were able to bind to WWP2-FL. The WWP2-FL and WWP2-N forms of the protein (but not WWP2-C) could bind to Smad3, although only WWP-C only bound to Smad7. 

The researchers found that when there was more WWP2 protein in the cell it increased how quickly Smad 2, 3 and 7 were removed. The acceleration of Smad7 removal was greater than Smad 2 and 3.

They found that the shorter, WWP2-N protein affected the activity of the WWP2-FL protein and made it more likely that WWP2-FL would bind ubiquitin to the Smad2 and Smad3, ultimately causing these proteins to be removed more rapidly.

The researchers additionally found that increasing the amount of WWP2-FL in the cells prevented the TGFβ protein from switching on the Smad2 and Smad3 genes. Decreasing the amount of WWP2-FL in cells using siRNA led to an enhancement of TGFβ-dependent switching on of the Smad2 and Smad3 genes.

After the researchers stimulated a cancer cell linewith TGFβ increasing WWP2-FL could affect the EMT process which. The WWP2-C and WWP2-FL proteins both shared a similar fragment. Introducing this fragment of protein into cells (by genetic engineering) caused the Smad7 gene to be more active.

 

How did the researchers interpret the results?

The researchers said that elevated TGFβ signalling activity (which stimulates gene activation and the mobilisation of cells) is associated with the cellular processes of human disease including fibrosis, heart disease and cancer metastasis. They suggest that the WWP2 protein plays a key role in preventing EMT, a process that may be involved in cancer metastasis. They say that part of the WWP2-C protein increases the levels of Smad7 and cite other studies that have shown that Smad7 inhibits EMT.

 

Conclusion

This preliminary study has made progress in understanding how WWP2 proteins interact with Smad proteins and has given some indication of how these interactions may affect cancer metastasis. The research work was done in cell-culture in the laboratory by genetically modifying the cells to either overproduce or not produce the proteins of interest. Further, direct investigation in cancer cells and tumour tissue sample are needed to see the importance of these proteins in cancer.

Some newspapers have correctly pointed out that this research was preliminary in nature, while others have wrongly implied that a cure for cancer will be available soon.

Italian scientists claim to have demonstrated cold fusion

Few areas of science are more controversial than cold fusion, the hypothetical near-room-temperature reaction in which two smaller nuclei join together to form a single larger nucleus while releasing large amounts of energy. In the 1980s, Stanley Pons and Martin Fleishmann claimed to have demonstrated cold fusion - which could potentially provide the world with a cheap, clean energy source - but their experiment could not be reproduced. Since then, all other claims of cold fusion have been illegitimate, and studies have shown that cold fusion is theoretically implausible, causing mainstream science to become highly speculative of the field in general.

Despite the intense skepticism, a small community of scientists is still investigating near-room-temperature fusion reactions. The latest news occurred last week, when Italian scientists Andrea Rossi and Sergio Focardi of the University of Bologna announced that they developed a cold fusion device capable of producing 12,400 W of heat power with an input of just 400 W. Last Friday, the scientists held a private invitation press conference in Bologna, attended by about 50 people, where they demonstrated what they claim is a nickel-hydrogen fusion reactor. Further, the scientists say that the reactor is well beyond the research phase; they plan to start shipping commercial devices within the next three months and start mass production by the end of 2011.

The claim

Rossi and Focardi say that, when the atomic nuclei of nickel and hydrogen are fused in their reactor, the reaction produces copper and a large amount of energy. The reactor uses less than 1 gram of hydrogen and starts with about 1,000 W of electricity, which is reduced to 400 W after a few minutes. Every minute, the reaction can convert 292 grams of 20°C water into dry steam at about 101°C. Since raising the temperature of water by 80°C and converting it to steam requires about 12,400 W of power, the experiment provides a power gain of 12,400/400 = 31. As for costs, the scientists estimate that electricity can be generated at a cost of less than 1 cent/kWh, which is significantly less than coal or natural gas plants.

“The magnitude of this result suggests that there is a viable energy technology that uses commonly available materials, that does not produce carbon dioxide, and that does not produce radioactive waste and will be economical to build,” according to this description of the demonstration.

Rossi and Focardi explain that the reaction produces radiation, providing evidence that the reaction is indeed a nuclear reaction and does not work by some other method. They note that no radiation escapes due to lead shielding, and no radioactivity is left in the cell after it is turned off, so there is no nuclear waste.

The scientists explain that the reactor is turned on simply by flipping a switch and it can be operated by following a set of instructions. Commercial devices would produce 8 units of output per unit of input in order to ensure safe and reliable conditions, even though higher output is possible, as demonstrated. Several devices can be combined in series and parallel arrays to reach higher powers, and the scientists are currently manufacturing a 1 MW plant made with 125 modules. Although the reactors can be self-sustaining so that the input can be turned off, the scientists say that the reactors work better with a constant input. The reactors need to be refueled every 6 months, which the scientists say is done by their dealers.

The scientists also say that one reactor has been running continuously for two years, providing heat for a factory. They provide little detail about this case.

 

One of three videos of last Friday's demonstration shows the reactor. The clicking sound is made by the water pump.

The response

Rossi and Focardi’s paper on the nuclear reactor has been rejected by peer-reviewed journals, but the scientists aren’t discouraged. They published their paper in the Journal of Nuclear Physics, an online journal founded and run by themselves, which is obviously cause for a great deal of skepticism. They say their paper was rejected because they lack a theory for how the reaction works. According to a press release in Google translate, the scientists say they cannot explain how the cold fusion is triggered, “but the presence of copper and the release of energy are witnesses.”

The fact that Rossi and Focardi chose to reveal the reactor at a press conference, and the fact that their paper lacks details on how the reactor works, has made many people uncomfortable. The demonstration has not been widely covered by the general media. However, last Saturday, the day after the demonstration, the scientists answered questions in an online forum, which has generated a few blog posts.

One comment in the forum contained a message from Steven E. Jones, a contemporary of Pons and Fleishmann, who wrote, “Where are the quantitative descriptions of these copper radioisotopes? What detectors were used? Have the results been replicated by independent researchers? Pardon my skepticism as I await real data.”

Steven B. Krivit, publisher of the New Energy Times, noted that Rossi and Focardi’s reactor seems similar to a nickel-hydrogen low-energy nuclear reaction (LENR) device originally developed by Francesco Piantelli of Siena, Italy, who was not involved with the current demonstration. In a comment, Rossi denied that his reactor is similar to Piantelli’s, writing that “The proof is that I am making operating reactors, he is not.” Krivit also noted that Rossi has been accused of a few crimes, including tax fraud and illegally importing gold, which are unrelated to his research.

Rossi and Focardi have applied for a patent that has been partially rejected in a preliminary report. According to the report, “As the invention seems, at least at first, to offend against the generally accepted laws of physics and established theories, the disclosure should be detailed enough to prove to a skilled person conversant with mainstream science and technology that the invention is indeed feasible. … In the present case, the invention does not provide experimental evidence (nor any firm theoretical basis) which would enable the skilled person to assess the viability of the invention. The description is essentially based on general statement and speculations which are not apt to provide a clear and exhaustive technical teaching.” The report also noted that not all of the patent claims were novel.

Giuseppe Levi, a nuclear physicist from INFN (Italian National Institute of Nuclear Physics), helped organize last Friday’s demonstration in Bologna. Levi confirmed that the reactor produced about 12 kW and noted that the energy was not of chemical origin since there was no measurable hydrogen consumption. Levi and other scientists plan to produce a technical report on the design and execution of their evaluation of the reactor.

Also at the demonstration was a representative of Defkalion Energy, based in Athens, who said that the company was interested in a 20 kW unit and that within two months they would make a public announcement. For the Rossi and Focardi, this kind of interest is the most important.

“We have passed already the phase to convince somebody,” Rossi wrote in his forum. “We are arrived to a product that is ready for the market. Our judge is the market. In this field the phase of the competition in the field of theories, hypothesis, conjectures etc etc is over. The competition is in the market. If somebody has a valid technology, he has not to convince people by chattering, he has to make a reactor that work and go to sell it, as we are doing.”

Are we freezing because of global warming?

Climate change could bring Britain ever more extreme weather, says Roger Highfield.