Let’s look at waste

It comes out of a nuclear reactor as spent fuel, although some of us prefer to refer to it as “used” fuel. The graph shows the decay of the usedt fuel of a typical light water reactor. The first thing to note is that it does decay until eventually it is less radioactive than uranium ore in the ground which would seem to be a satisfactory situation compared with other waste products which are permanent.

One should also mention that rich ore deposits of pitchblende are 100 times more radioactive and they exist naturally without causing a moments concern to the general public.

But one has to say that it takes a rather long time to reach the uranium equivalent and most people believe that the waste should in the meantime be buried deep underground for safe keeping. Fine. However we can do much more in the interim to make matters better.

We can recycle the plutonium and unused uranium to produce 20% to 30% more energy as MOX fuel in today’s reactors. This is what the French are doing, the Japanese are starting and Germany, Switzerland and Belgium have done it with used fuel reprocessed in France and the UK but have now stopped reprocessing. There is now no economic reason why the US and other countries should not do the same. In particular the UK where we have already carried out the reprocessing and have separated plutonium just waiting to be put back in a reactor but are stupidly refusing to complete the recycle. It is said that we could produce enough MOX fuel to power two large 1600 MWe EPR’s or three 1000 MWe AP-1000’s for their entire 60 year design life.

Now look again at the decay curves. The thing that extends the cross over point with uranium out to thousands of years is mainly the long lived actinides – americium-241 and -243. It is not plutonium which is only eight times the uranium level today. Plutonium is an alpha emitter which, in the words of the inspector of theWindscale Inquiry, can be stopped by a “stout pair of jeans.” However americium is associated with plutonium as a decay product.

If we recycle the plutonium we also remove the americium from the decay curve. It is mixed in with the MOX and partially burnt in the reactor to short lived radioactive fission products. Admittedly this is not as beneficial as the fission of plutonium and uranium because it does not produce as much energy. But there will still be a reduction in the usedMOX fuel. The physics is complicated because americium is both formed by neutron bombardment of plutonium and destroyed by fission while it is in a reactor.

So you need to have its detailed history to sort out what you have. Roughly speaking one can say it will be eight times less for one recycle of MOX. So removal of the plutonium and americium by recycling reduces the decay curve to short lived fission products which crosses over with uranium at a few hundreds of years. Of course we still have the MOX used fuel but it takes the plutonium from about eight uranium used fuel elements to create oneMOX element. So the radioactivity of plutonium is already down to the uranium equivalent and the americium is only ten to one hundred times higher. That’s about the same as naturally occurring pitchblende. We can recycle again as MOX although that introduces a few complications. Alternatively we could wait for the reinvention of the fast reactor or one of several fourth generation reactors being developed. This would almost completely remove the plutonium and the americium from the decay curves.

Technology available

How about the recycling technology? Or “reprocessing” to use the American’s nasty word.

Today’s operating reprocessing plants – two in France and one in the UK – use the PUREX process. This makes use of a e solvent extraction process of contacting an organic and an aqueous solvent which first separates uranium and plutonium from short lived fission products. This cleans the used fuel of the 4% of fission product that would otherwise prevent it from being reused. Then in the French and British plants a further stage of solvent extraction is used to separate the uranium from plutonium products. But this is not necessary. You can leave the uranium-plutonium products already mixed for MOX fuel. This is what the Japanese are going to do. The French have also developed the so called COEX process for the eventual replacement of their plants. Astudy in 2006 forAreva by the Boston Consulting Group showed that a COEX plant with a capacity of 2500 te/yr could be built and operated in the US to make recycle of used fuel economically competitive in comparison with their currently favoured direct disposal.

Many other processes are being studied in France, the US, Russia and Japan but this is mainly in connection with advanced fourth generation reactor designs. These could be very important in future years but for the time being we can achieve a great deal by recycle of MOX in today’s plants.

NDA strategies

In looking at the subject of plutonium on the internet we came across a report dated January 2009 entitled NDA Plutonium Project Strategy. This is an examination by the Nuclear Decommissioning Agency of options for dealing with the nearly 100 te of separated plutonium held in the UK. It might have been expected to answer all our questions. But it does not. It ought to have raised some press interest but it does not seem to have done so. Perhaps the NDA were keeping quiet about it because they failed to reach any clear conclusions.

The main absence is consideration of using the material as soon as possible in UK reactors. This option is excluded because it is not currently UK government policy. “The option of recycle in the UK has not been considered in the analysis undertaken to date, as it is believed that this would require a change to the Governments current stance with respect to justification and licensing of reactors for MOX fuels, although in principle it is judged to be technically feasible ….” Well surely the NDA as practically the last organisation we have with technical nuclear knowledge should be trying to do something about this. They should be urging a change of policy for Sizewell B. British Energy was allowed to abandon its reprocessing commitments when – due to Government policy – it found itself in financial difficulties. No such allowance was made for overseas reprocessing contracts.

Also the NDA or British Energy should re-examine the use of MOX in AGR’s. This was established as feasible some years ago but was judged at that time to be uneconomic. But now the whole economics of energy production has been turned on its head and the case might be very different today.

The NDA merely observes that: “In the event that UK policy allowed utilisation ofMOX in the UK there would be a significant reduction in the costs of this option ....”

The only MOX recycle options considered are for use in CANDU heavy water reactors presumably in Canada and overseas reactor probably in Europe. Just why these countries should be interested in using our plutonium when we refuse to use any of the stuff ourselves is not clear.

Our plutonium is described several times as a “zero value asset.” ZERO VALUE!! It has been estimated to be sufficient to fuel two 1600MWe EPR’s or three 1000MWe AP-1000’s for 60 years. Hardly zero value. It would produce far more electricity than we could possibly get from the 7000 wind turbines that the government is currently proposing to build at vast cost.

The NDA appears to reject the use of the Sellafield MOX Plant (SMP) except for the production of low grade MOX for one of its several disposal options. It looks like they are intent on getting their decommissioning hands on this plant which was built at a cost of £600 million.

They also reject the use of any new fourth generation plants designed to recycle virtually all the used fuel. These are too far in the future.And redevelopment of the good old fast breeder is not even considered.

Needless to say the NDA does not reach any firm conclusion although it seems to favour continued interim storage in some sort of Fort Knox facility. This would at least leave open the option of using the stuff more productively in the future.

Best in a reactor

The safest place to “store” plutonium and the associated americium once it has been separated from short lived fission products is in an operating reactor. This allows the production of a large amount of desperately needed, carbon free, energy. It would fission much of the americium to relatively short lived radioactive products. It reduces the amount of waste by a factor of eight (it takes destruction of eight uranium spent fuel element to produce the plutonium for one MOX element.) It would buy time for the development of more advanced fourth generation reactors or the redevelopment of the old fast reactors which open up complete recycle. And for the scaremongering proliferation critics, it would impose an intense radiation barrier that even the most suicidal terrorist would hesitate to try to penetrate.

The technology of MOX use is well developed. The plants to produce it are in place as long as the NDA keeps its decommissioning hands off.Why not do it?... NOW!

A low carbon strategy

The Government commitment to achieving a low carbon economy is not in doubt. The publication of four bulky documents - The UK Renewable Energy Strategy and The UK Low Carbon Transition Plan are supported by a Low Carbon Industrial Structure Plan and Low Carbon Transport – a total of almost 800 pages examine in detail how carbon emissions might be reduced, even down to estimates of the potential reduction of emissions from the transport sector by training bus drivers. But it is difficult to extract from this mass of information exactly how electricity demand is to be met and security of supply ensured, or to believe the figures put forward.

While there is a welcome acceptance of a role for new nuclear power stations the overwhelming emphasis is on the generation of electricity from renewable sources, mainly meet the unfortunate and probably unworkable EU requirement that 15%of energy must come from renewables by 2020 - which will require the generation of 30% of electricity from renewable energy sources. The problem of maintaining electricity supply is also heightened by the required closure by 2018 of 16 older coal fired power stations, about 25%(18 GWe) of existing capacity under the EU Industrial Emissions Directive.

Possibly to simplify the task it is assumed that there will be no growth in electricity demand which by 2020 will remain at 386 TWh. This is not too far from the CBI adoption of 400 TWh by 2030. Yet the projected increase in electric vehicles and an expansion of rail electrification to cut carbon emissions from the transport sector would require an increase in electricity output. At one point in these reports it is suggested that electricity usage by 2050 could increase so that “our demand for electricity in 2050 could be 50% higher than it is today, making it possible that electricity could account for half of our overall energy use.”

The assumed growth of renewable electricity supply is marked by an unbridled optimism. ‘Learning by doing’ is expected to reduce the capital cost of wind in 2020 by 10- 15%. For offshore wind, while it is admitted to be technologically more challenging than onshore wind, it is claimed that the stronger and more consistent winds will give a higher output per turbine and more generating hours per year. Yet experience so far shows that the actual load factors of offshore wind farms at 25.6%are even lower than for onshore at 27.5%(2007). These might be initial teething troubles, but it also seems to be assumed that the turbines now installed offshore will still be operating 10 or 20 years later. Perhaps it is with these potential problems in mind that £120 million is to be spent on the further development of offshore wind technology. The subsidy to offshore wind production may also be increased further from the 1.5 ROC’s/MWh recently announced to 1.75.

The same optimism is seen with regard to other potential renewable forms of generation. Despite the disappointments of the past 40 or 50 years and the failure to produce a workable device, wave power is seen as a future electricity source with the quotation of an estimate from the Carbon Trust that Britain has “a practically attainable wave resource of around 50 TWh of electricity a year”. To this end £60 million is to be spent on developing these technologies with a “Tidal Hub” being established in Cornwall. It is unfortunate that a photograph chosen to illustrate wave generation is of the Pelamis device, developed in Scotland and installed off the Portuguese coast which had to be brought ashore after two months and may be abandoned.

The costs of these programmes will be considerable and are expected to increase household electricity bills by 15%.

Here again it is optimistically argued that increased energy conservation and efficiency of energy usage together will reduce electricity consumption and thus limit the increase in domestic electricity cost to 8%. There are however good arguments for believing that increasing efficiency of use can lead to greater consumption.

The reports recognise the problems associated with the intermittency of wind output but believe that higher wholesale prices for electricity at times of peak demand will provide sufficient returns for investors in the flexible power stations required to operate for the time when renewable electricity generation is not available. They even seem to welcome the fact that prices would reach sufficiently high levels on a sufficient number of occasions and for a sufficient time to allow the investors to recover their costs.

But then there are second thoughts and it is admitted that the amount of renewable electricity on the system could potentially become a problem after 2020 due to the closure of the older gas and coal power stations which provide valuable flexibility to the electricity system.

One welcome feature is the recognition of the part to be played by nuclear power. While no limit is placed on the number of new nuclear power stations that may be built, it is expected that, to maintain the current share in the energy mix, some 9 GWe of nuclear power capacity will need to be added - between 6 and 8 nuclear reactors - over the next ten to fifteen years. Although small by comparison to the sums to be spent on renewables £15 million will be provided to establish a Nuclear Advanced Manufacturing Research Centre to assist British suppliers to take some share in provision of components and assemblies to the main reactor suppliers. This will go some small way to remedy the damage done when our nuclear reactor programme was abandoned after Sizewell B and British nuclear capability for reactor design and construction and the manufacture of nuclear fuel was sold off under the polices of Blair, Hewitt, and Meacher.

Wind power myths

The summary of a report from the Renewable Energy Foundation on Danish wind power casts doubt on the widely accepted assumption that Denmark has successfully integrated more than 20% of its electrical energy from wind power, with the implication that the UK will be able to replicate this success with ease and at reasonable cost. It points out that since the Danish and German spot markets are closely correlated Denmark and Germany behave like one electricity market and that a new entity “Germany-and- Denmark” has absorbed around 7% wind power, not the 20% attributed to Denmark alone.

Despite the relatively large geographical area, there is very little smoothing of the output of wind power in Denmark and the E.ON Netz control area of Germany, and the outputs of both countries are consequently strongly correlated, sometimes being close to zero for days or even weeks. This lack of smoothing means that wind power significantly increases spot price volatility, with very high prices observed at times of low wind (when conventional generators are required to take up the slack). In 2007 spot prices rose to peaks of up to €650/MWh, but there were also very low or even negative prices at times of high wind. The report suggests that the significant economic implications for investors of this spot price volatility will lead to an unstable market, and deter investments in the rest of the electricity system.

The Dept of Energy and Climate Change may proudly boast that having overtaken Denmark “the UK is currently No. 1 in the world for operating offshore wind farms” (press release of 30 March), but the United Kingdom, far from being safely behind the Danish “frontier of experimentation”, as previously supposed, is now advancing into unknown territory, as Government policies require upwards of 30% of electrical energy to be generated from wind power (as opposed to 1.5% in 2007), far beyond the 7% of “Germany-and-Denmark”. There are many potential problems.

The UK is not strongly linked with continental Europe and even if all current plans proceed, the UK will be weakly connected in proportion to its market size. If high levels of wind are to be built in the UK this can only occur with the provision of major, and costly, internal grid balancing services, including, for example, demand management, and electricity storage, as well as flexible, rapid response generation as well as the timely provision of further interconnectors to mainland Europe and Norway, to facilitate electricity trading.

A growing understanding of the capacity credit of wind shows that the UK system must always have sufficient reliable generating plant to meet peak load (plus a safety margin), since, because of its uncontrollable variability, wind can make little or no contribution to this “firm” generating fleet. Since, as a result of EU legislation the UK is faced with plant closures of about 30 GWe of older coalfired capacity, equal to around 50% of peak load, new investment in firm, clean, and flexible low-carbon plant will be required over the next decade. It is a major concern that the significant price volatility of wind power could undermine confidence in the electricity market, and thus act as a disincentive to investment in urgently needed new nuclear carbon-free generation.

The report concludes that “In the absence of a solution, the proposed UK wind fleet will either not be built or will be forced to curtail output. This has implications of cost to the consumer (if curtailment is compensated), or costs to the generator if it is uncompensated. The attainment of environmental targets would also be threatened.”

Renewable Energy Foundation: Wind Power and Spot prices: German and Danish experience 2006-2008, 12.05.09: London Array Power May be Curtailed Press Release 13.05.09. This study was conducted for REF by Mr Paul-Frederik Bach, one of Denmark’s most experienced and distinguished power system engineers. As Planning Director at Eltra, the Transmission System Operator inWest Denmark, he was in charge of affiliation to the Nordic spot market for electricity, Nord Pool, in 1999, and until retirement in 2005 his main responsibility was the integration of wind power. He is now active as a consultant with an interest in the safe and efficient integration of wind power, particularly prevention of disturbances by advanced system control measures.

Impact of Intermittancy

A study by the Pöyry energy consultancy of the expected consequences of 35-45 GWe of wind power on the British economy confirms and reinforces the doubts highlighted in the REF study.

While the REF study was based on the present wind generation of Denmark and Germany the Pöyry analysis uses the wind profiles of 2008/9 to estimate the consequences to be expected in 2030 for the UK and Northern Ireland when, to meet the EU target, the UK wind capacity will be 35-45 GWe.

By 2030 the ‘spikeyness’ of electricity prices, from very low or even negative at times of high wind to very high prices identified in the REF study, becomes, with the greater wind output, even more extreme, with highs of up to an astonishing £8000 MWh, at times when the wind output falls. They make the point that in a future high wind market the probability of extremes is more important than averages.

The analysis also shows that periods of high wind are not correlated with periods of high electricity demand as is often claimed by the wind enthusiasts. The smaller partner Ireland could obtain some benefit with an interconnection to its larger neighbour (as does Denmark) but there will be little benefit for the UK.Wind patterns of the UK and Ireland are similar, as in the case of Germany and Denmark. Interconnectors cannot be seen as a “golden bullet”.

The counterpart of the variation in wind output is that the operation of the back up supply, assumed to come from CCGT and coal stations, will also be intermittent and could vary between only a few hours a years in one year to some hundreds or thousands the next. The revenues from these back-up stations will then be highly uncertain and give no clear signals to the generating companies on investing in the new plant that will be required. The functioning of the ‘energy only’ British electricity market which will discourage low loads investment in plant that may only be called upon to operate at unpredictable and often very short periods.

This may require the introduction of capacity payments to ensure that the new plant will be built. In effect the Government will have to subsidise the construction of the necessary back up plant if the returns on the capital invested will be too uncertain for a commercial company. The costs of such a subsidy should then be added to the already extreme cost of wind. This will not only push up electricity prices and force an even greater part of the population into fuel poverty but impose a heavy burden on industrial production and damage the economy.

Blind faith

Perhaps the most alarming conclusion of the Pöyry study is the final paragraph - “At the outset of this work we believed that it was vital to inform the debate about the importance of wind in decarbonising the electricity supply by informed quantitative analysis. This has proved a major challenge, but the richness of the information has surprised even the project team, and while the answers we have are often complex, we believe that any debate on the role of wind can now be properly informed.”

This suggests that the targets set by the EU and enthusiastically adopted by the UK in decisions taken to expand wind output have not been “properly informed and were in thewords of theREF littlemore than “a leap in the dark.”.

It is now obvious that the problems with wind are not only complex but certainly very costly. Decarbonised electricity can be generated more reliably and for a fraction of the cost in nuclear power stations.

CBI

The Confederation of British Industry has also contributed to the energy debate with a report - Decision Time: driving the UK towards a sustainable energy future - commissioned from McKinsey and Company. The CBI believes it will be difficult for the industry to build enough renewable electricity generation by 2020 to deliver the 32% of generation seen as necessary to meet the EU target; attempts by the Government to force the pace of wind deployment further through additional incentives, could push up prices to consumers and also make wholesale prices more volatile; it would then be prudent to reduce the targeted amount of renewable electricity for 2020 from 32% to perhaps 25%. It urges a more “balanced pathway” with the construction of eight nuclear power stations on existing sites. With what is seen as the inevitable delays in planning and licensing the earliest date for a start of construction would be in 2013 for operation by early 2018.

By 2030, when 10-15 reactors could be in operation, the main components of electricity generation capacity, in GW, built up under the “balanced pathway” compared with a “business as usual” programme would be:

                        Balanced pathway      Business as usual

Gas                                10                                25

Nuclear                          16                                10

Wind                              25                                34

Coal with CCS                  7                                  4.5

Other                               7                                  5.5

For the balanced pathway the percentage share of the projected total generation of 400 TWh in 2030 (CBI assumption) would be: Nuclear 34, Wind 20, other renewables 15, Gas 16, Coal 2, Coal with CCS 14.

The CBI pathway claims advantages for both energy security and reduction of carbon emissions. By reducing the gas used in power generation in 2030 by almost 20% the total UK gas demand could fall from 99 bcm to 80 bcm at a time when over 90% of UK gas consumption will be imported as production from the North Sea declines. [While the report optimistically believes that gas imports are not “inherently risky”, it must be probable that by 2030, as world consumption increases, ‘peak gas’may follow ‘peak oil’ as a matter of growing concern and lead to ever higher prices, particularly as the CBI believes over half the imports would be as LNG.]

Carbon emissions would fall with the reduction in gas consumption and the presumed adoption of CCS for almost all coal-fired generation. But this latter assumption could again be optimistic. The high costs, reduced energy output, and safety considerations could make this technology unacceptable. On the CBI figures carbon emissions in the balanced pathway would meet the 2030 targets and, at about 33 te CO2, be 45% lower than the business as usual scenario.

The key factor in these proposals is the reliance on nuclear power as the most cost effective way of delivering both carbon reductions and increased security of energy supply.

A word about americium

This is an artificial element first produced by Glen Seaborg in 1944. He was carrying on work to follow his discovery of plutonium. By bombarding plutonium with neutrons he produced the even heavier artificial element and called it americium.

It has found widespread use in smoke detectors.You may have one in your kitchen. The gamma emission is low energy and alphas are easily stopped. (By a pair of stout jeans.)And the radioactive sources are very small. So there is no significant risk.

Very much larger quantities are produced in a nuclear reactor by bombardment of plutonium as it is produced with neutrons. There is a transitional isotope of plutonium in the decay chain so americium will continue to be formed once used fuel is removed from a reactor. The two main isotopes of americium-241 and -243 have half lives of 432 and 7 370 years respectively. It is generally considered that plutonium from used fuel should be recycled as soon as possible to avoid the build up of americium though this message does not appear to have penetrated the brains of British officials.

There are ways of scrubbing americium from plutonium but you still have the problem of disposing of it.