Could Hinkley Point C Creep Past Safety Limits And Overload Its Waste Storage ?
by Jo Abbess
24 November 2013
The use of high burn-up nuclear fuel in the Hinkley Point C nuclear power plant, if it goes ahead, could lead to higher levels of waste than claimed in the design, owing to the increased chances of operating failures. It could also make power generation more prone to unreliability, due to unplanned outages. Added to this, safety measures do not rule out the kind of large scale and costly accident-by-design seen at Fukushima; nor the risk of a major disaster from mismanagement of the insecure spent fuel facilities, which would be wide open to a terrorist attack.
The Hinkley Uncertainty Principle
In the UK Government’s 2011 consultation on the management of plutonium, separated from spent nuclear fuel, their stated policy would be to “pursue reuse of plutonium as mixed oxide fuel [MOx]”, although they couldn’t yet determine whether MOX fuel would be produced in the UK . Reprocessing abroad would involve highly secretive and dangerous transportation, so how and why did they come to this expert judgement ?
Some claim that using plutonium oxide to make fresh nuclear fuel would “eat up” highly toxic and militarily dangerous plutonium waste, however this is not true. Using MOX fuel in a nuclear reactor creates almost as much in plutonium as it consumes – so why have the UK Government decided to take the MOX route ? Possibly because it feeds into plans by EDF Energy to build a new nuclear power plant that would use some “high burn-up” nuclear fuel in its two reactors, burning up to 50% higher than at other working plants, and MOX is probably the cheapest fuel option.
Counter-intuitively, high burn-up fuel doesn’t get used up faster than other nuclear fuel. It produces more heat energy under neutron irradiation than the usual mildly-enriched uranium oxide, because it can split the atoms of a higher percentage of the fuel. It can “burn up” for longer, and be left in the reactor core for longer, before it needs to be changed out for fresh fuel. Or that is the theory, anyway.
Some of the products of nuclear fission are noble gases, one of which is radioactive xenon, and although this is gas produced inside solid nuclear fuel pellets, packed into a long sealed metal casing, “fission gas” shouldn’t cause the fuel rod to burst – although it might make it swell a bit, or become deformed. There is a tiny risk this could mean fuel rods burn up dangerously higher, or get stuck when being taken out of the reactor, or that control rods might be unable to go in, all of which would be problematic.
But back to the gas. Some radioactive xenon will make it out of fuel rods into the reactor coolant, because the integrity of fuel rods is not 100% guaranteed. If a fuel rod starts leaking badly, it ought to be swapped out for fresh fuel, because it could “dry out” and get precariously hot, and that could mean shutting down the reactor, which would affect its “always on” reliability.
In the Hinkley Point C Generic Design Assessment final report on “Gaseous radioactive waste disposal and limits”, it admits, “Reactors are designed to run until their next refuelling shutdown with a small number of fuel leaks and we do not wish to constrain operations when noble gas discharges have so little impact.” What they’re saying is, in effect, we know some of these fuel rods are going to be broken in a live, working reactor. What they can’t know is, which ones ?
It’s a little bit like Schrödinger’s Cat – you can’t know if a fuel rod is dead until you take it out of the box to inspect it. If xenon levels in the reactor coolant rise above the permitted levels, as a direct result of fuel damages from high burn-up, the plant operators would need to intervene, because it’s not just fission gas they should be concerned about. Leaking fuel rods could spit particles of uranium, or plutonium, into the reactor coolant, which could end up in the general environment, and that would have a significant impact .
It will be possible to do some inspection checks without removing fuel rods entirely from the core. But in all likelihood, with high xenon emissions levels, they would need to shut the reactor down, by inserting control rods into the core to moderate the neutron flow. With normal nuclear fuel rods, this is a low-impact operation, but laboratory experiments suggest that for high burn-up, stopping and restarting the reactor, cooling and then re-heating the rods, will cause significant damage to the nuclear fuel .
Cracked and crumbling high burn-up fuel could release more fission gas, so the very process of checking the integrity of fuel rods could damage the integrity of the fuel rods, and make xenon emissions worse, and mean more swaps for fresh fuel rods, meaning more radioactive waste to deal with. Because spent nuclear fuel will eventually need to be officially classified as radioactive waste, although currently it isn’t.
The design for this nuclear power plant claims to produce less waste than current models, but that all depends on how the plant operators can manage high burn-up nuclear fuel rods, and it’s too early to say, since there isn’t a working version of this reactor anywhere in the world yet.
So it’s a little like the Heisenberg Uncertainty Principle in Quantum Physics – you can’t know exactly how damaged your fuel rods are, and exactly how much spent fuel waste you’re going to produce, at the same time. The tempation, of course, will be to leave the fuel in and the reactor on for as long as possible, even though the statistical probability for loss of fuel integrity will just increase with time.
Hot rods could be good future business
I am still waiting for the Nuclear Decommissioning Authority to tell me where I’ve gone wrong on the maths, but from my preliminary calculations, I estimate that the radioactive waste and radioactive spent nuclear fuel from this one new plant will nearly double the amount of radioactivity in nuclear materials the UK has to dispose of. In terms of the physical size of the rad waste, it won’t add much to the total, but some of the spent fuel coming from Hinkley Point C will be very hot rods from high burn-up – and I don’t just mean radioactive, I mean literally hot, potentially far hotter than steam.
The design for the plant includes an essential “cooling off” pool of water, which would be like a “shadow” reactor core, but without the safety containment vessel. Because of the temperature of the fuel rods, a lot of water will be needed. The hot rods will have to stay in there being actively cooled for up to 10 years after they come out of the reactor, as they will be producing around 10% of the heat energy they produced when inside the active reactor.
And after they’re cool enough to come out of there, the fuel will have to sit under water in a storage pond, also actively cooled, for around about 80 to 90 years, until enough radioactive decay has taken place that the fuel then becomes reasonably safe for geological disposal. Although we haven’t got a Geological Disposal Facility (GDF) yet. And some calculations suggest we might need two. If we don’t have the right volume of GDF, perhaps the Hinkley Point C hot rods could just have to sit in the on-site “interim” storage facility forever.
If the plant operators have to swap out more high burn-up fuel rods than they anticipate, perhaps the spent fuel storage facilities at Hinkley Point C will be too small for the full 60 years of waste designed for the plant. If it were only large enough for 35 years of operation, that would conveniently match the length of the very generous subsidies for the power the plant will produce. Thereafter, the plant operators could declare they cannot afford to keep the power plant running, and the state could be obliged to subsidise them simply to store the hot waste.
The transition business model for the operators of Hinkley Point C could be the service of the storage of hot radioactive spent fuel, perhaps, when it becomes obvious that nuclear power is simply too expensive compared to solar and wind power. Will Hinkley Point C end up like San Onofre, a high burn-up spent fuel waste facility, formerly a nuclear power plant, corroding its way towards being a serious liability ?
Going LOCA, down in Taunton
When asked, “Should we have nuclear power ?”, many gaze at the mid-distance, and, according to recent polls, muse vacantly, “I suppose so. I mean, the wind doesn’t always blow, and the sun doesn’t always shine.” They probably don’t realise that filling in the generation gaps of renewable electricity with power from Hinkley Point C would demand load-following power cycling which would cause temperature changes in the reactor core which could damage high burn-up fuel .
Plus, they choose to ignore the fact that it is always possible, when operating a nuclear reactor, for a major accident, such as a Loss Of Coolant Accident (LOCA), that could destroy, poison and injure people, livestock, forests, waterways and land, and not just in the local vicinity. They consign it to a remote theoretical possibility that something could go horribly wrong, but it probably won’t, so that’s all right then, somehow. Well, we’ve had decades of nuclear power, and not many serious accidents.
Ah, there was Chernobyl, of course, which the whole of the European Union is still paying to clean up and put under a massive steel dome shelter, and the costs of the meltdown and fallout arguably destroyed the economy of socialist Russia. And the ongoing, unfolding, rolling disaster shambles that is the Fukushima Dai-ichi make-safe operation, set to go on for at least a decade ? Well, the clean-up is eating into Japan’s GDP, and they will have to give up investment in cleantech and meeting their carbon budget targets, and burn coal, because, frankly, the country’s broke; but nobody really suffered, did they ?
We lost Pripyat, we almost lost Detroit, and we could still lose Tokyo, but who really cares about Taunton – the town near Hinkley Point ? No humane person would wish the citizens of Taunton to die a painful, lingering death, or suffer a lifetime of various cancers and degraded health, or be forced to relocate to Yarmouth or York, permanently. Somehow, the awfulness of this possible eventuality just cannot be captured.
Rudimentary statistics of human health and the social consequences of evacuation don’t really describe effectively what is happening in Fukushima Prefecture – there are some impacts of an nuclear power plant disaster you really cannot put a number on. OK, so there will only be a certain number of deaths and cancers, but what about the destruction of a community and the impaling of an economy ?
Remember 9/11 ? Aeroplanes were flown into the World Trade Center, not just the tallest buildings in New York, but symbols of the USA-led economy, which was then drained by the American obsession with warfare, since an entirely predictable kneejerk response to the attack was military counter strike, which nobody can really afford any more. The pilots of those planes were targeting economic dominance, not high rise office workers, and they succeeded.
Nuclear power plants can have costly accidents and are expensive to build and safely close down; but although nobody seems to have a handle on safe and effective spent fuel disposal, in some ways, these risks are calculable. In contrast, spent nuclear fuel ponds would be ideal targets for suicidal dirty bombers, and the threat of this is unknowable, because it doesn’t need the use of anything so obvious, large and noisy as an aeroplane to spring a leak.
Meltdowns are designed in – threatening economic security
Officials may deny that Fukushima Dai-ichi Reactor Unit 3 went LOCA when it melted down. Technically it was a LUHS – Loss of Ultimate Heat Sink, or an SBO – a Station Blackout – but it had pretty much the same outcome, as the water covering the fuel in the reactor probably vapourised, or got chemically converted into hydrogen gas, which then exploded and blew the roof off. It was part-loaded with “hot rod” MOX fuel, which makes it the one to watch during clean-up operations – that is, when it’s not so radioactive that only robots can get near it .
Can the multiple nuclear reactor unit meltdowns, explosions, radioactive plumes and leaks at Fukushima properly be counted as an “accident” ? Meltdown of a nuclear reactor core is always an anticipated possible outcome, that’s why they put it in a containment vessel, cast out of a single piece of steel . So, it could be argued, these disasters are technically planned for, rather than coincidental, tragic failures. It was in the documentation : after an emergency shutdown, if all forms of reactor cooling became unavailable at a Fukushima unit, within a couple of hours there would be inevitable major core damage, and the risk of meltdown. It was part of the design. It’s part of the design documentation for Hinkley Point C, too.
If the Fukushima units had done their job, and contained the meltdowns, and the cooling systems had remained operational, then one could be reasonably confident that Hinkley Point C (HPC) could too; but they didn’t. The design of HPC has an extra thick concrete base under the reactor vessel, just in case nuclear fuel melts through, with channels grooved into it to steer any meltdown mess from accumulating in one place, thereby trusting it won’t become “critical” again.
But meltdown and melt-through is not the only kind of serious event HPC could suffer. Use of high burn-up fuel could contribute to warped fuel rods or control rods, higher build-up or leaks of fission gas. And its higher temperatures, together with the high pressure of the reactor coolant, could cause a range of high energy damage, or even prevent a safe shutdown; and until they permitted the plans to go ahead, the UK Government’s Assessment Findings had much to question as regards control systems.
In conclusion, there will always be the risk of a major, uninsurable accident with the UK EPR (TM) design for Hinkley Point C, and even without considering health and safety, the long-term costs of cleanup could wipe out everybody’s pensions. My opinion is that we cannot afford this risk, just as we can no longer afford warfare. Why do the UK Government persist in proposing that the people should bear the cost burden and risks of new nuclear power, when there is already an alternative suite of energy and energy management technologies that can be built in roughly half the time and three quarters of the cost ?
 What do to with UK plutonium ?
DECC (2011). “Management of the UK’s Plutonium Stocks : A consultation response on the long-term management of UK-owned separated civil plutonium”, UK Government, Department of Energy and Climate Change, 1 December 2011.
Leventhal (1995). “Bury It, Don’t Burn It : A Non-Proliferation Perspective on Warhead Plutonium Disposal”, Paul Leventhal, President, Nuclear Control Institute, Presented to the U.S. Department of Energy Plutonium Stabilization and Immobilization Workshop, Washington, D.C., December 12, 1995.
Royal Society (2011). “Fuel cycle stewardship in a nuclear renaissance”, Royal Society, October 2011
USA (2000). “Agreement Between The Government of the United States of America and The Government of the Russian Federation Concerning the Management and Disposition of Plutonium Designated as No Longer Required for Defense Purposes and Related Cooperation”, 2000.
von Hippel et al. (2012). “Time to bury plutonium”, Nature, Volume 485, 10 May 2012.
 Fuel fragmentation and dispersal
Papin et al. (2003). “Synthesis of CABRI-RIA Tests Interpretation”, Papin et al., Proceedings of the Eurosafe Conference, Paris, November 25 – 26, 2003.
ONR (2011). “Generic Design Assessment – New Civil Reactor Build : Step 4 Fuel and Core Design Assessment of the EDF and AREVA UK EPR (TM) Reactor.”, Office for Nuclear Regulation (ONR), Assessment Report : ONR-GDA-AR-11-021, Revision 0, Section 4.9.2 Paragraphs 200 – 202, 10 November 2011.
NEA (2010). “Safety Significance of the Halden IFA-650 LOCA Test Results”, Nuclear Energy Agency, OECD, Committee on the Safety of Nuclear Installations (CSNI), Document : NEA/CSNI/R(2010)5, 15 November 2010.
UB (2013). “Hinkley Point C : Expert Statement to the EIA”, Oda Becker, UmweltBundesamt (Environment Agency Austria), Wien 2013, Document Number : REP-0413.
 High burn-up fuel
Baron et al. (2008). “Discussion about HBS Transformation in High Burn-Up Fuels”, Baron et al., in Nuclear Engineering and Technology, Volume 41, Issue Number 2, March 2009, Special Issue on the Water Reactor Fuel Performance Meeting 2008.
Blair (2008). “Modelling of Fission Gas Behaviour in High Burnup Nuclear Fuel”, Paul Blair, PhD Thesis Number 4084, École polytechnique fédérale de Lausanne (EPFL), 2008.
CEN (2011). “Review and Assessment of the Key HBU Physical Phenomena and Models : Assessment of International Return of Experience on High Burnup Fuel Performance in Support of Licensing for Burnup Increases in Belgian NPPs”, Lemehov et al., SCK-CEN, Document SCK-CEN-R-4824, Project 10.2 – Report #1, November 2011.
IAEA (1992). “Fission gas release and fuel rod chemistry related to extended burnup”, International Atomic Energy Agency (IAEA), Proceedings of a Technical Committee Meeting held in Pembroke, Ontario, Canada, 28 April – 1 May 1992, Document Number : IAEA-TECDOC-697, 1993.
IAEA (2001a). “Nuclear fuel behaviour modelling at high burnup and its experimental support”, International Atomic Energy Agency (IAEA), Proceedings of a Technical Committee meeting held in Windermere, United Kingdom, 19 – 23 June 2000, Document Number : IAEA-TECDOC-1233, 2001
IAEA (2013). “Technical Meeting on High Burnup Economics and Operational Experience”, International Atomic Energy Agency (IAEA), to be held at Buenos Aires, Argentina, 26 – 29 November 2013, Information Sheet, 2013.
ONR (2012). “Summary of the GDA Issue close-out assessment of the Electricité de France SA and AREVA NP SAS UK EPR (TM) nuclear reactor”, Office for Nuclear Regulation (ONR), Health and Safety Executive (HSE), Generic Design Assessment, 13 December 2012.
ONR (2013). “Nuclear Research Needs 2013 – Part 1: Summary of Nuclear Research Needs”, Office for Nuclear Regulation (ONR), Health and Safety Executive (HSE), Section 15, “Nuclear fuel Research”, 2013.
Rondinella and Wiss (2010). “The high burn-up structure in nuclear fuel”, Rondinella and Wiss, European Commission, Joint Research Centre, in Materials Today, Volume 13, Issue Number 12, December 2010.
 Nuclear Power Plant load-following
EDF (2013). “Load Following : EDF Experience Feedback”, EDF Energy, at IAEA Technical Meeting – Load Following, 4 – 6 September 2013, Paris.
IAEA (2001b). “Fuel behaviour under transient and LOCA conditions”, International Atomic Energy Agency (IAEA), Document Number : IAEA-TECDOC-1320, Proceedings of a Technical Committee meeting held in Halden, Norway, 10 – 14 September 2001.
Lokhov (2011). “Load-following with nuclear power plants”, Lokhov A., Nuclear Energy Agency, NEA Updates, NEA News 2011, Issue Number 29.2
NEA (2006). “Very High Burn-ups in Light Water Reactors”, Nuclear Energy Agency, OECD, Document Number : NEA No. 6224, 2006.
NEA (2011). “Technical and Economic Aspects of Load Following with Nuclear Power Plants”, Nuclear Energy Agency, OECD, 2011.
Pouret and Nuttall (2007). “Can nuclear power be flexible ?”, Pouret, L. and Nuttall, W.J., Electricity Policy Research Group Working Papers, Number 07/10, 2007. Cambridge: University of Cambridge.
 Mixed oxide fuel (MOX)
ANS (2011). “The Impact of Mixed Oxide Fuel Use on Accident Consequences at Fukushima Daiichi”, American Nuclear Society, 25 March 2011.
Kim et al. (2010). “Ceramography Analysis of MOX Fuel Rods After Irradiation Test”, Han Soo Kim et al., Korea Atomic Energy Research Institute, 27 July 2010.
Lyman E. S. (2001). “The importance of MOX Fuel Quality Control in Boiling-Water Reactors”, by Edwin S. Lyman, Nuclear Control Institute.
Nakae et al. (2012). “Fission Gas Release of MOX Irradiated to High Burnup”, Nakae et al., in TopFuel 2012, Reactor Fuel Performance, Manchester, England, 2 – 6 September 2012.
Popov et al. (2000). “Thermophysical Properties of MOX and UO2 Fuels Including the Effects of Irradiation”, Popov et al., Oak Ridge National Laboratory, 2000.
 Nuclear reactor containment
Large (2007). “Assessments of the Radiological Consequences of Releases from Existing and Proposed EPR/PWR Nuclear Power Plants in France”, John Large, Large and Associates, Document : R3150-3, 17 March 2007.
TEPCO (2011). “The Evaluation Status of Reactor Core Damage at Fukushima Daiichi Nuclear Power Station Units 1 to 3”, Tokyo Electric Power Company (TEPCO), 30 November 2011.
TVO (2010). “Nuclear Power Plant Unit Olkiluoto 3”, TVO, December 2010.
There are several documents in the first bunch of references that suggest UK Government want to take the MOX route for “getting rid of” plutonium stocks [or rather “losing” it in the matrix of the final spent fuel]. For example, advice from the Royal Society, and the consultation from UK GOV. I checked with […] regarding high level direction, and it appears UK GOV are fixed on this course of action. They might open a new MOX production facility in the UK (although they just closed one down), and they might get MOX made abroad using UK plutonium, to use in UK reactors. The point to note is that EdF uses MOX elsewhere. Although EdF are currently denying they will use it, Hinkley Point C could :-
[ MOX fuel has been reported as being intended for the new PRISM reactor :- ]
I have tried to steer the conversation to the use of high burn up fuel generally (MOX is only one option for high burn up fuel). High burn up fuel could be made from different kinds of enriched uranium. There [seems to be] a clear move [drawn from the design documents] from EdF to use high burn up fuel at Hinkley Point C – in fact, the claims in the design that the plant will produce low volumes of spent fuel relies on them using high burn up fuel. For example :-
Of course, if EdF do not use high burn up fuel or MOX fuel, they will [in all likelihood] produce far larger amounts of spent fuel waste than they are claiming, so it adds to the argument that their rad waste claims could be unverifiable.
A recent statement in the House of Commons claims that spent fuel from Hinkley Point C will be :-
“The new build contribution to the Upper Inventory is estimated at an additional 25,000 m(3) [cubic metres] intermediate level radioactive waste (ILW), and 20,000 m(3) [cubic metres] Spent Fuel”
from all the new build reactors (16 GW) anticipated. But this could be an underestimate if they use standard enrichment levels in the nuclear fuel.
The design and safety documents for Hinkley Point C have a limit of burn-up set at 65 GWD/tU – and there are many other statements about the layout of the reactor – roughly 30% could be high burn-up.
Example from Pre Construction Safety Report (PCSR) :-
Sub-Chapter 4.2 Fuel System Design
“1.1. FUEL RODS : Fuel rods are composed of slightly enriched uranium dioxide pellets with or without burnable poison (gadolinium), or MOX (uranium and plutonium) dioxide pellets. The fuel is contained in a closed tube made of M5 [Ref-1] [Ref-2] hermetically sealed at its ends.”
There have been queries about the performance of the M5 (TM) Zircaloy (zirconium alloy) under high burn-up, and power/thermal transients, which have been largely quashed, for example :-
although the nuclear industry claim it’s all good :-
Section 7.2.3 “The key factors in demonstrating the minimisation of the production of radioactive waste are…”
“3.2 THE ASSESSMENT PROCESS (MADA)
3.2.1. Definition of Interim Spent Fuel Store (ISFS) Requirements
126.96.36.199 Spent Fuel Quantity and Characteristics
The reactor core of a UK EPR would typically consist of 241 fuel assemblies providing a controlled fission reaction and a heat source for electrical power production. Each fuel assembly is formed by a 17×17 array of zirconium alloy (such as M5) tubes, made up of 265 fuel rods and 24 guide thimbles. The fuel rods consist of uranium dioxide pellets stacked in the zirconium alloy cladding tubes which are then plugged and seal welded. It is currently assumed that a maximum of 90 spent fuel assemblies (SFA) would be removed every 18 months of operation from each UK EPR. Taking into account the time allowed for planned maintenance outages over the anticipated 60 years operating life, a total of approximately 3,400 assemblies are expected to be generated by each UK EPR. The lifetime operation of HPC, comprising two UK EPRs, would therefore result in a total of around 6,800 spent fuel assemblies. Fuel cladding failures cannot be ruled out over this period and so the interim storage does need to be capable of receiving “failed fuel” within adequate packaging.
Fuel composition and burn-up is a very important parameter for spent fuel management since it determines the heat load and the rate at which this reduces after the fuel is discharged from the reactor. The ISFS needs to be able to store enriched uranium fuel at the maximum design burn-up of 65 GWd/tU in accordance with the fuel envisaged in EDF Energy’s Development Consent application. However, the EPR is capable of accepting mixed oxide fuel (i.e. fuel where plutonium instead of uranium oxide is used to provide some or all of the initial fissile material) and, whilst EDF Energy has no current plans to use MOX fuel, it is considered prudent to ensure that the ISFS design could enable fuel with higher thermal power or different composition to be stored (noting, of course, that this eventuality would be subject to the receipt of all relevant Government and regulatory approvals).”
SNEAKING SUSPICION :- I think that the UK Government […] might push for MOX to be used in the first nuclear power plant that becomes available that can do so.