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2007 Nuclear Issues v29 07 |
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Written by Nuclear Issues
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Sunday, 01 July 2007 |
Nuclear Issues is also available as a pdf download
Gordon Brown in favor of nuclear
In his first Prime Minister’s question time Gordon Brown has at least
demonstrated a positive attitude toward new nuclear power plants in the
UK. Replying to opposition questions he said “The security of our
energy supply is best safeguarded by building a new generation of
nuclear power statons.” It is significant that he said a “new
generation of nuclear power stations.” This could mean that he has
recognised that we are talking about a third generation design of
reactor rather than one of the old first generation Magnox plants that
have been so heavily – though wrongly – criticised for decommissioning
costs.
As we reported last month the cost of decommissioning the first generation Magnox reactors is about ten time higher than a modern third generation plant.
Good and bad management
It is tempting to assess the performance of nuclear power stations by their annual load factors; a view endorsed by the nuclear journals which report and compare the load factors achieved by different reactor systems and companies.
On this basis the performance of British Energy under the new management imposed on the company by the Government at the time of the reconstruction in 2002, — without any previous experience in nuclear power and gas cooled graphite reactors — has not been encouraging. The average annual load factors of BE’s nuclear stations have fallen from 81% in 2001/2 to 76%, 77%, 71%, 72% to 61% in 2006/7. The output from the nuclear stations has likewise has fallen from 67.57 TWh in 2001/2 to 51.21 TWh in 2006/7.
In contrast the recovery of the Canadian Candu stations now operated by Bruce Power from a state of near collapse to average load factors of 89%, under the leadership of a former director of British Energy who left that company at the time of the reconstruction, might be seen as an example of good management.
But matters are not that simple. An examination of BE’s performance figures shows that the poor performance is largely due to failures in some of the AGR stations with boiler tube cracking at Hunterston B and Hinkley Point B, giving load factors of 33% and 39% respectively for the past year, and refuelling problems at Dungeness B 47%. In contrast another AGR station, Heysham achieved 74% for unit 1 and 88% for unit 2. The PWR station Sizewell B has also consistently performed well with a load factor of 85 % in 2006/7.
Other indicators of performance also show mixed signals. Unplanned losses at BE’s nuclear stations have tended to increase from 13% 02/03 and 03/04 to 18% 04/05, back to 13% in 05/06 and a jump to 23% in 06/ 07. On the other hand unplanned automatic trips have fallen from 23 in 02/03 to 25, 15, 12 and 8 in the succeeding years while nuclear reportable events which have to be notified to the nuclear inspectorate under the site licence conditions and which can be taken as an indication of safe performance have also fallen from 66 in 02/03 to 77, 47, 36, and now 22 in 06/07.
Forsmark
Events at the Forsmark nuclear power station in Sweden suggest that high load factors and high availability do not necessarily ensure that high levels of safety are always maintained. The three Forsmark BWR reactors by ASEA have over the past 10 years consistently recorded energy availability of over 90% dropping only to 83 and 87 % in two of those years.
On 25th July 2006 an incorrect switching operation in a 400 kV switchyard, outside the responsibility of the power station, caused a short circuit and voltage drop which brought Forsmark-1 to an emergency stop, Reactor-2 was already shut down for refuelling; Reactor-3 was also brought to a stop. This should have triggered a full response from the automatic emergency safety systems – (Uninterruptible Power Supply) – a battery array designed to ensure that the alternating current to important safety systems is maintained. In the event only two of the four independent systems came in to operation. As a consequence only two out of four emergency diesel generator systems operated as intended, and much of the instrumentation for the control room was also lost.
This failure of the automatic safety system could have led to a more serious incident, but the control of the reactor is overseen by the plant operators, who after only 45 seconds began the first checks in accordance with the Emergency Operating procedures. After 22 minutes, the control room manually connected the sub A and B diesel generators to their busbars, so that all four systems were now working: Supervisory facilities in the control room were restored; greater capacity was available for pumping water into the reactor pressure vessel, so that the normal water level was quickly restored; motor powered insertion of the control rods was completed accompanied by indication that all the rods were inserted.
After extensive checks, the control room personnel were able – 45 minutes from the initial event – to enter a brief record in the logbook that “The reactor is safely sub critical and operational status is stable”. The shift team dealt with the incident in accordance with procedures that they had trained in the simulator, dealing with situations similar to that which actually occurred Despite a confusing signal situation, and loss of video screens, the control room staff carried out their work in accordance with their instructions in a particularly effective manner. This event was rated as a level-2 event on the IAEA nuclear reporting system.
The initial failure was of the four independent UPS systems. These were installed at Forsmark-1 & 2 over ten years ago. They replaced equipment based on mechanical technology, which was more resistant to electrical disturbances. Tests that were carried out after the incident by the supplier systems showed that the overvoltage protection operated as expected with voltage variations in the range 85-110 % of nominal value. In this case, the voltage variation that actually occurred was more than the UPS systems could deal with. The fact that the systems A and B were knocked out, while those in C and D were not, was probably due to small differences in the electrical circuits, which could have resulted in the voltage fluctuations on C and D being less than those on A and B.
This failure has been a matter of serious concern for the Swedish safety who have sought a ruling as to whether an offence against the Nuclear Safety Act was committed and that the company should be prosecuted.
They have also examined the other nuclear stations, Oskarshamn and Ringhals to see whether weaknesses similar to those found in Forsmark 1 were present.It ws decided that Forsmark 2 and Oskarshamn 1 and 2 should not be allowed restart until investigations had been carried out and reported, and any necessarywork carried out, as these plants contained partially similar equipment.
Forsmark 3, Oskarshamn 3 and the four Ringhals units could be kept in operation without alterations.
Authorities with allegations that the safety culture has slipped and that warnings from the plant operators had been ignored by a management dominated by business interests. It seems that the high availability figures may have been achieved by neglecting sasfety.
There could clearly be a commercial conflict between shutting a station down to deal with minor deficiencies or maintaining high load factors. The problem is in determining where issues of plant safety arise. Under the joint ownership – 66% by the Swedish State Power Board with Finnish and German power companies as the remaining major partners – there would be an incentive to give priority to maintaining a high output.
Although there was no question of any immediate danger to the public this event has shaken public confidence in nuclear power in Sweden. The percentage willing to accept an expansion of the nuclear programme has dropped. The situation has been made worse in that a more intensive scrutiny of Forsmark by the nuclear regulatory bodies has uncovered other evidence of minor failure, notably a deficiency in the instrumentation recording discharge of radioactive material into the atmosphere. The station has been shut down.
Burying Carbon
In a reaction to the increasing prices and impending shortages of oil and gas the world is turning again to coal. Since 2002 world coal consumption had, by 2006, increased by 27 percent. To lessen the inevitable increase in carbon dioxide emissions that will follow, let alone meet the reductions that most countries have signed up for, great reliance is being placed on the assumption that carbon capture and storage (CCS) technology for fossil-fired electricity plants will be widely adopted. This assumption is often used to justify delays in the expansion of nuclear power – the only reliable energy source available on a sufficient scale to reduce fossil fuel burning. But is this assumption valid? The capture limb of this technology is perhaps feasible – at a price. Some small-scale plants to recover carbon dioxide are already in operation, but on a large scale it will add considerably to the cost of coal-fired electricity as well as reducing the efficiency of the stations to an extent that may limit its adoption in those developing countries, which are now rapidly increasing their coal consumption.
There are also serious doubts over whether carbon dioxide can be safely stored underground for long periods of geological time and in sufficient quantity to make any appreciable difference to climate change.
The study “Belgian Energy Challenges towards 2030”, commissioned by the Minister of Energy and published last month concluded on this point that – “It would be irresponsible to assume that CCS would be available and to think that there is an escape route from CO2 emissions. We must therefore conclude that the scenarios with CCS allowed are interesting exercises, but should not be held for actual policy making.” The reasons are explained – “a coal fired unit with net power output of about 800 MWe needs to capture and store about 5 million ton/year of CO2. It seems very unlikely that storage in Belgium can become a reality before 2030 given the 200 – 400 million ton of carbon dioxide that could be produced by 2030. With these huge amounts that need to be handled, it is not unreasonable to state that routine commercial ‘disposal’ of this CO2 will be ‘difficult, if not quasi impossible’”.
This was one of the arguments used in the study which led to recommendation that the nuclear option should be kept open and the nuclear phase-out reconsidered.
The problem is significantly greater for the UK where, in 2005, the major power producers consumed 50.6 million tones of coal. With a carbon content of between 60 – 80 percent for bituminous coal this would produced roughly some 100-150 million tonnes of carbon dioxide per year – a quantity that can only be expected to increase with the expectation that coal consumption will continue to rise. The UK target for a 60 percent reduction in carbon emissions by 2050 is only likely to be approached if emissions from fossilfired power stations are contained. Over this period these will amount to something of the order of 10 000 million tonnes; a daunting task.
Apart from the quantity there are other serious problems. The critical point for carbon dioxide is 304.1 o K (31oC) and 73.8 bar, conditions that are likely to be met if the gas is pumped into a geological system, when the distinction between liquid and gas phases disappears. Supercritical carbon dioxide is a powerful solvent (and is used as such commercially). It also has applications for enhanced oil recovery (EOR). There is now talk of disposing of the captured carbon in the depleting North Sea oil fields; this would not only increase the oil production but much of the injected carbon dioxide would come to the surface together with the recovered oil to give a net increase in carbon emissions when the oil is burnt. The solvent power of the carbon dioxide would also seem to make it unsuitable for injection into disused coal mines (although again this might be used as a means of increasing coal production).
This solvation problem is not just a theoretical possibility; there are reports of an experimental injection of 1 600 tonnes of liquid CO2 carbon dioxide into a depleted oil field in Texas. This caused the minerals underground to dissolve, with the implication that the liquid CO2 could then leak into ground water or find its way back into the atmosphere and aggravate the greenhouse effect.
The long-term safety of the storage must also be in doubt. Given the huge quantities and the mobility of the gas/liquid, the possibility of leakage with potentially disasterous consequences if a populated centre is blanketed by the gas cannot be discounted. It will be difficult if not impossible to ensure the safety of any storage over a very long period of time. Storage under the sea bed is also likely to arouse opposition.
Against this the widely debated ‘problem’ of nuclear waste disposal must seem trivial. The quantities in comparison are minute. The volume of high level liquid waste from the reprocessing of 30 tonnes of spent fuel released annually from a 1 000 MWe plant, containing more than 99% of the radioactivity, is some 10 cubic metres. In addition the nuclear waste can be immobilised when vitrified to a glass solid so prevent the possibility of any leakage of radioactivity. It should also be noted that unlike radioactivity which decays over time the dangers associated with a massive leakage of carbon dioxide will continue unchanged for ever.
Belgian phase out not possible
A major report commissioned by the Belgian government to guide energy policy to 2030 says that maintaining the phase out programme of the previous government is a non starter. Belgium needs nuclear power as an economic and low carbon source of energy and continuing the current programme would lead to a doubling of electricity prices, would greatly reduce the country’s potential for reducing carbon dioxide emissions and would lead to dependency on imports.
The Belgian energy report is a mine of useful information and analysis of energy consumption and supply. The following is one example of an “Informative Box.” The relative cost of “nuclear fuel” as part of the cost for nuclear electricity generation is relatively small since nuclear power is mainly capital dominated.
Therefore, the fluctuations of uranium prices do not have a big impact on the final nuclear electricity generation cost. It is important though to distinguish between the cost of the nuclear resource material (usually referred to as “yellow cake”) U3O8 and the cost of the nuclear fuel cycle, which encompasses the nuclear fuel elements that will be put into the reactor and the “downstream”, “back-end” or waste-management part.
According to the IEA World Energy Outlook 2007 the fuel (-cycle ) cost amounts to 7% to 14% of the total electricity cost, depending on the assumed discount rates and the assumptions for capital investment[68 [IEA, 2006d] considers furthermore that about 25% of the fuel-cycle cost is for waste management. To produce then the PWR nuclear fuel elements, starting from U3O8, over conversion and enrichment to pellet sintering & assembly, the following numbers apply: uranium resource cost ~ 25% of total fuel cost, conversion ~ 5%, enrichment ~ 30% fuel assembly ~ 15%. All this leads to a contribution of 1.75% to 3.5% of the U3O8 resource cost to the overall nuclear kWh cost.
With these numbers, a doubling of the so called (total) nuclear fuel-cycle cost would lead to an increase of the kWh price by 7% to 14%, whereas a doubling of the resource U3O8 purchasing price, would lead to an increase of the kWh price by about 2% to 4%. An increase by a factor of 10 of the (total) nuclear fuelcycle cost would lead to an increase of the kWh price by 63% to 126% (or thus roughly by a factor 1.6 to 2.3), whereas an increase by a factor of 10 of the resource U3O8 purchasing price, would lead to an increase of the kWh price by about 18% to 36% (or thus roughly an increase by 1/5 to 1/3).
In some countries, the cost for the back end takes up a larger part of the fuel-cycle cost, so that the relative influence of U3O8 price fluctuation is even smaller than indicated here.
EPR progress in US
Electricite de France (EDF) has formed a joint venture with Constellation Energy in the US to further push plans for a fleet of the US version of Areva’s European Pressurized Water Reactor (EPR) in US and Canada.
Unistar Nuclear Energy (UNE) was formed in 2005 as a joint venture with Constellation to develop a framework for building at least four of the giant 1600 MWe units in North America. With the help of Areva the process certification of the design with the US Nuclear Regullatory Commission was started. Bechtel Power Corporation is also supporting Unistar with engineering and construction expertise and in mid 2006 a first agreement was signed with EDF for technical assistance at the utility operator level.
EDF has now become a 50-50 partner with Constellation in the UNE holding company and has pledged $350 million cash up front and a total of $625 million support for the joint venture which will build, own and operate the EPR unit in the US.
Meanwhile Unistar has submitted the first part of a combined construction and operating license (COL) application to the Nuclear Regulatory Commission for the construction of a 1600 MWe EPR at Calvert Cliffs.
There are two existing 865 MWe PWR’s operating at Calvert Cliffs. The NRC has given Unistar six months to submit the second part of the COL which would include a safety analysis for the plant.
Indonesia opts for Korean reactors
Indonesia’s PT Medco Energi International has signed a memoradum of understanding with Korea Electric Power Corporation (KEPCO) and Korea Hydro and Nuclear Power Company (KHNP) for the building of the country’s first nuclear power plants. This could involve two of the standard 1000 MWe Korean Pressurized Water Reactors. The expected cost would be about $3 billion.
This would be the first major export order for the very successful Korean standardised reactor which is based heavily on the System 80 design of US Combustion Engineering. The agreement is part of a wider energy collaboration.
Chinese contracts for AP1000
Westinghouse, along with its consortium partner Shaw, has now signed contracts for the supply of four AP1000 units with China’s State Nuclear Power Technology Corporation (SNPTC), the Sanmen Nuclear Power Company, Shangdong Nuclear Power Company and the China National Technical Import and Export Corporation for four AP1000 units. These could be the first AP1000 units to be built and the contracts could include major technology transfer for the design which involves extensive use of passive safety features. The first two units are to be built at Sanmen with construction starting in 2009 and first power expected by 2013.
Loviisa good for another 20 years
Finland’s first nuclear power plant at Loviisa was a little unusual in employing a Russian design of reactor with Western design of containment and instrumentation but it has defied all the critics and performed amongst the best in the world with capacity factors in the high 90 percent for year after year. Now the two small reactors of 440 MWe have been given the green light for another twenty years of operation by the Finnish regulatory body, Stuk. This will take the units to 2027 and 2030. Stuk expects to carry out two periodic safety reviews in 2015 and 2023.
A major concern is embrittlement of the pressure vessel steel from irradiation by neutrons. But Stuk thinks that this will be all right following stress relieving of the vessels. Otherwise the Russian reactor design has several features which make it superior to Western reactors. These include the large volume of water in the pressure vessels and horizontal heat exchangers.
Nuclear desalination for Libya
France and Libya have signed a memorandum understanding to cooperate on a nuclear desalination plant that is being proposed for Libya. The agreement was signed during a recent visit to Libya by the French President, Nicolas Sarkozy.
Enough fuel for 60 years
According to a report by the Nuclear Decommissioning Authority the UK has enough uranium and plutonium in stockpile to provide the fuel for three 1000 MWe reactors for their entire 60-year life. The Authority plans to discus the use of this material with the government.
Nuclear Issues has been urging for many years that we should be thinking about some of these stockpiles.
We believe that there is considerably more if one also takes into account all the depleted uranium put aside as tails from enrichment plants. This material can be converted into more plutonium fuel by irradiating it in fast reactors.
It used to be said that this material was not economic unless the prices of new uranium rose by about three or four times. Now it has risen by some ten times and is currently trading at a spot price of $135 per pound of U3O8. So surly it is time to start using are valuable energy resource.
Lithuania ready to go
An agreement was signed into law by Lithuanian President Valdas Adamkus on 4 July for the construction of a new nuclear power plant. A new company will be established by the end of 2007 with the status of a “national investor” to undertake the construction.
Lithuania was operating two large reactors of the Russian RBMK type similar to Chernobyl. These were appropriately modified after the Chernobyl accident and were judged by international experts to be adequately safe. But in order to get acceptance of Lithuania’s application for membership of the European Union it became necessary for the reactors to be closed down prematurely. They were at least as safe as contemporary Western plants but bureaucrats in Brussels insisted on earlier closure demands. Thus Lithuania had to abandon the position of the largest producer of nuclear power – compared with national electricity production – and waste many millions of pounds of investment. |
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