Once again we are approaching the summer break after another successful year for the Society. This year has seen major work carried out at the Observatory at considerable cost and Council wishes to express its thanks to all those members who made generous donations to the maintenance fund and to all those members who helped with the actual work.
Membership has remained fairly constant close to 120 and meetings have been consistently well attended. This is in no small measure due to the efforts of the Programme Secretary who, as always, strives to produce a varied and interesting lecture programme. He would like to hear from you, if you have suggestions for topics that you would like to see covered in future lectures.
There are now just two meetings to look forward to in the current session. The final lecture of the session takes place on May 16th when Dr. John Eyre (University College London) will talk on:
DESIGN OF ENGINEERING STRUCTURES.
IMPORTANT NOTE: THE ANNUAL GENERAL MEETING IS: THURSDAY JUNE 20TH AND NOT 16TH AS PRINTED ON THE PROGRAMME CARD. Apologies for this printing error!
As usual the AGM will be preceded by wine & cheese and if time allows, followed by a scientific entertainment.
The agenda will include reports from officers and section leaders and the election of officers and five ordinary members of Council for the coming year. Council proposes the following:
Treasurer & Membership Secretary
Ordinary Members (Max 5)
|Dr. Julie Atkinson
Julia Daniels, Dr. Kevin Devine, Roger O'Brien, Peter Stern and Martin Williams.
Council invites further nominations for the above posts. Such nominees should be duly proposed and seconded and should have agreed to serve if elected.
According to the Constitution, Ordinary Members of Council are obliged to stand down when they have served four consecutive years. In June 2014 this will apply to four out of five Ordinary Members who will therefore need to be replaced all at the same time. Council considers that it would be more sensible to replace one Ordinary Member every year in future, ensuring a regular turnover of Council members without the risk of losing too many people at once. Council therefore proposes the following amendment to the Constitution (shown in bold) so that the new rule will apply at the next AGM in 2014:
5. Officers – Council (current wording)
Council proposes that Clause 5b is amended to read as follows:
Council also seeks ratification from members at the AGM to bestow Vice-Presidency on Julia Daniels.
Julia Daniels (nee Willcox) joined the HSS aged 18 in 1956 and was first elected to Council in 1959 (the same year as Heinz Wolff). She made observations of Mars and variable stars, and became an Observatory Demonstrator in 1960. She married Doug Daniels in 1965. She has been Astronomy Section Treasurer for 41 years so far (since 1972) and Roster Secretary for much of that time. She wrote the 16-page history of the Astro' Section in the Society's history, from the Society's yearbooks and from personal memory and records. Although physical frailty prevents her continuing as a regular Demonstrator, she is still a very active member of the Society and the Astronomy Section, and she helps out wherever needed at meetings.
Peter R Wallis
Not everyone believes in the threat of global warming caused by our burning fossil fuels: oil, coal and gas, but all realize that these fuels will eventually run out.
Many are calling vociferously for us to change to renewable energy. We now have many giant windmills (often opposed by local residents and ship-masters when they are offshore) and occasional solar power arrays on roofs (in spite of the UK shortage of sun). But some of us realize that these energy sources are rather unreliable and when they are inoperable they need to be backed up by other systems. Those of us who are concerned about global warming hope that these can be low in the emission of carbon dioxide. At present the worst offenders by a long way are coal-fired power stations. In my view the most urgent UK requirement is to replace coal by gas – a dash for gas. Gas is still a fossil fuel of course and we have changed from being an exporter to become an importer. In the United States a new technology gas extraction from underground shales by hydraulic fracture (fracking) has greatly increased availability and lowered the cost by a factor of 3. We need to do the same if we can; it would be nice not to be dependent upon Russian gas. One of the potential areas is in Lancashire where the additional employment would be welcome and also attract other firms who need cheap power. There are similar rock formations in the Midlands and South East.
The only longer term solution however is the use of nuclear power. Nearly 20% of the UK's electrical power is already nuclear (in France the figure is 90%) but most of our nuclear stations are more than 30 years old and will need replacing. What system should we use? You may remember the HSS visit to see the Joint European Torus, JET, at Culham. This is a research programme to develop a fusion reactor, in which energy is released by the fusion of hydrogen to form helium; this is the reaction that powers all the stars. It's the ideal long term solution but may not be available in my view till the next century. An alternative approach in the US using lasers, the National Ignition Facility, failed to meet its objectives and has been terminated.
There are some 437 nuclear power reactors operating around the world. These are all based on the fission of uranium 235. Of these 356 are light-water reactors. These use ordinary water as a moderator to slow down the neutrons released from a split uranium nucleus from their original energy of some 2 million electron volts (ev) to less than 1 ev, which more readily split another uranium 235 atom in the chain reaction. The water also acts as a coolant for the core and to carry the heat released to the steam generator that drives the turbine and alternator. We have one such light-water reactor at Sizewell, but the others are gas-cooled using carbon dioxide and graphite as a moderator.
There are two problems with the light-water reactor. The first one is that a failure of the water flow allows the reactor core to heat up, even if nominally switched off, and it may melt down. Overheating occurred at Three Mile Island in 1979 in the US and also in three reactors at Fukushima Daiichi in Japan in 2011, though neither actually reached meltdown; in the recent case the zirconium cladding reacted with water to generate hydrogen, which exploded. Emergency back-up cooling systems are provided but, in the recent case, were overpowered by the tsunami.
A second problem arises from the use of slow neutrons. Natural uranium is only some 0.7% uranium 235, though usually increased to some 3% in the reactor fuel; the rest is uranium 238, which is non-fissile. Unfortunately some of the slow neutrons add themselves to the uranium 238 to form plutonium 239 and other heavy elements, eg neptunium, americium, curium etc. These can have a long life (the half-life of plutonium is 24,100 years) and are responsible for the nightmarish problem of radioactive waste disposal; nobody knows how to guarantee isolation over such long times. Plutonium, in particular, can be separated chemically and being itself fissile presents a proliferation problem. Indeed, in 1974, India tested a bomb made from plutonium separated from spent nuclear fuel. This led President Carter to ban all reprocessing in the US.
One solution to the waste problem is to have a "fast" reactor, ie one without a moderator. The fast neutrons may not hit their target so often, but they can split it reliably and are only rarely absorbed. They can also destroy many of the long-lived isotopes in the waste. To build a fast reactor one needs a coolant that doesn't slow the neutrons too much. One possibility is liquid sodium. The UK used this at Dounreay in Scotland but it has since been decommissioned. Sodium reacts violently with water to generate hydrogen so is not a good choice to drive a steam generator in a power station. General Electric/Hitachi in North Carolina have proposals for small fast reactors using liquid sodium (the S-PRISM ) aimed at destroying waste or unwanted stocks of plutonium.
There is another system which is now being considered to avoid the melt-down risk of the light-water reactor, a molten salt reactor. This was originally proposed at the Oakridge Laboratories in the US in the 1960s, but not followed through. The molten salt refers to the fuel of uranium tetrafluoride, which is liquid at operating temperatures when mixed with lithium fluoride and beryllium fluoride which acts as coolant. This is circulated through an external unit where the fission products that can poison the chain reaction are eliminated; it is claimed that it should be an easier process than in reactors with solid fuel which has to be replaced regularly. These fission products are short-lived and do not present such a problem as the fusion products mentioned above. Of course there is a risk of overheating if an emergency stops the liquid circulating. The company Flibe Energy proposes that a hole at the bottom of the reactor vessel is sealed by a plug of fuel which is kept solid by a refrigerator; if power is lost and the liquid heats up, the plug melts and drains the fuel into holding tanks with a geometry preventing further chain reaction. Being such a new design, it may well take a decade or more to be built, proved and accepted by the regulators.
But there is more. The proponents of the molten salt reactor say that, because it is a liquid system, it could use thorium as a fuel as well as uranium. This could be a fundamental game changer. Natural thorium is made up of thorium 232, an isotope which is non-fissile; it is estimated to be 3 or 4 times as abundant as uranium. When irradiated with neutrons however it changes in stages to uranium 233, which is fissile. (Details: thorium 232 captures a neutron and becomes thorium 233 with a half-life of 22 minutes, decaying to protoactinium 233. This has a half-life of 27 days, decaying to uranium 233. ) One cannot start a reactor with thorium alone, as we need the irradiation by neutrons, but if we start it using uranium (or possibly plutonium) we can keep it going using only thorium, I guess. This would mean that our power could eventually come from almost 100% of the world's thorium, instead of 0.7% of the world's uranium and building up massive stocks of plutonium and higher poisons. I do not know whether conventional solid reactors could also change over to thorium fuel.
It seems to me that it would be sensible for the UK to acquire some fast reactors to dispose of the legacy of plutonium and wastes. I think we should look seriously at the molten salt reactor system, if the ideas discussed above can be confirmed. No doubt this will take time. Serious consideration should be given to the use of thorium as fuel. We should eliminate coal-powered stations as soon as we can.
It is surely about time for the Government to get to grips with the whole energy problem. We have a diminishing supply of fossil fuels and much of the gas and oil on which we presently rely is imported from countries with less than stable political regimes. The emerging economies, China, India and South America are competing for increasing fuel supplies and consequently the pan-global price will inevitably rise. We have only to examine our domestic fuel bills to realize that this is already happening. The present and previous governments, have adopted an 'ostrich-like' policy to the problem, they seem unable to look further than five years ahead – the time to the next general election.
Vast amounts of money are being spent on 'renewable energy' programmes, building masses of giant windmills. But these are dependent on the weather which in this country is fickle to say the least; the wind may not blow at times of peak demand. Other 'renewables' such as tidal power generators, which could be more reliable than wind, are still in their early development stages.
Many of our existing nuclear power stations are soon due to be decommissioned with no plans having been made for their immediate replacement. Only now we hear that planning permission has been granted to the French company EDF to develop a reactor at Hinkley Point; it will be 10 years at least before it is fully operational, if in fact it does actually go ahead.
This country still has massive reserves of coal, the use of which is being phased out in favour of cleaner natural gas. The chief opposition to the use of coal fired power stations is the emission of carbon dioxide which may be contributing to accelerated climate change. To reinforce this position, Didcot A. power station was shut down on March 25th 2013 after 43 years supplying power to two million homes – to be replaced by what? Surely it is not beyond the wit of engineers to design a process that can clean up these emissions before venting them to the atmosphere, so that we could continue to use our coal fired power stations in the short term. In the meantime we should harvest our reserves of shale gas where it is safe to do so to lessen our dependency on imported fuels. But in the long term, we must develop strategies that do not depend on burning fossil fuels.
The greatest source of energy freely available to all is of course the Sun. If every house in Britain had roof top solar panels supplied by the generating companies and connected to the national grid, it would contribute greatly to our daily requirements. Making use of heat pumps and geothermal activity should also be exploited where possible, as well as wind and tidal power. We should certainly be building replacement nuclear reactors as soon as possible and more funds should be available for continuing research into nuclear fusion – the ultimate 'Holy Grail' of cheap energy.
Perhaps we should also consider using less electricity, although this tactic would be anathema to the supply companies who will always want to sell us more to increase their profits and dividends to their shareholders. For this reason it might ultimately be preferable if the generation and distribution of power were to pass from the hands of commercial enterprises to a government authority and treated as a strategic resource as it was during the second world war. The notion that putting energy supply into the hands of private companies would increase their competitiveness is clearly flawed. At least one supplier is currently facing charges of unethical sales techniques and ripping off their customers and has been ordered to make restitution. The overseeing authority 'Ofgem' has shown itself to be less than vigilant controlling these companies, all of whom have made it almost impossible for the average consumer to determine which supplier (if any) is the most competitive. Using any excuse, one of the suppliers will increase their prices, swiftly followed by all the rest. One could be forgiven for thinking that there is some form of cartel in operation, arranged by the suppliers to maximize profits at the expense of consumers.
In an increasingly populated and industrialized world, the demand for affordable energy appears insatiable so we should fully exploit all available sources of energy and formulate plans for the future when fossil fuel reserves are finally exhausted. If we fail to do this very soon, the lights will be going out a lot sooner than expected.
Scientists have recently announced that the cure for agoraphobia is just around the corner!
Last updated 27-Jan-2018