Fukushima Part 2- Assessing the safety of nuclear power after 03/11

In my fourth blog assessing the viability of living without nuclear energy, I came to the conclusion that it would be unwise to scrap nuclear power altogether. If the climate models are right, we risk environmental, economic and societal cataclysm should we choose a 'business as usual' strategy. Action is needed fast and I felt the yield available from nuclear power per kilogram and per acre would be highly valuable. Especially in areas where renewable alternatives are a long way off. 

Last week the Japanese government blaming its shuttered nuclear industry slashed its 2020 GHG emissions target to a 3.8% drop versus 2005 levels, this amounts to a 3 % rise from the UN benchmark year of 1990 and a reversal of the previous target of a 25% reduction, could this be commonplace if there is an exodus away from Nuclear power? Source: Huffington Post, 2013  

However after last week’s blog whilst I agree with all of the above I can’t help but recognise the inherent risk of nuclear power. Yes, events like Chernobyl and Fukushima could be termed accidents triggered by human error and 'uncontrollable' natural events. However once the flame was lit, the proceeding fire bore the characteristics of a recalcitrant technology eliciting a cascade of further problems (Pritchard, 2012). 

How might industry officials and supporters of nuclear power respond to this claim and justify increased investment in nuclear energy moving through the 21st century? 

Many would argue that nuclear energy does ultimately have a good safety record. According to Sailor (et al 2007) outside of the Soviet union about 8500 reactor years of commercial nuclear power plant operation had been realised up to the year 2000 without any large external release of  radioactivity, and only one accident with fuel melting (i.e. Three Mile Island in 1979).  From this Sailor (et al, 2007) averaged the risk of an accident involving fuel damage as 1 in 10000 reactor years based on Generation II reactors. At face value this seems reasonable, but let's say we turn to nuclear power to curve emissions, and by 2050 it is responsible for a 1/3 of global electricity demand. This would require up to 4000 plants and the expectation would be for an accident involving fuel damage every several years! 

This figure is shocking, but it is derived from a past average over a period where safety likely improved considerably. In fact by analysing data on the occurrence of individual system malfunctions (precursor events) it has been estimated that the probability of core damage fell by a factor of roughly 100 when comparing the 1994-1998 record to 1974-1978 alone. Generation III reactors developed in the late nineties and coming into fruition now, promise even greater safety. 

Schematic of an Advanced boiling water reactor, these Generation III reactors have been estimated to have a probability of core damage as low as 2x10^-7 per reactor year, or one accident in every two hundred million years running Source: Mowry, 2000

The above figures are impressive but what about when we bring seismic activity into the equation, what does the nuclear industry do to reduce the risk it poses? 

In the USA, the largest consumer of nuclear energy, even plants that are located outside areas with extensive seismic activity  are designed for safety in the event of a natural disaster.  They take the most severe natural phenomena historically reported for the site and surrounding area, and then add a margin for error to account for limited historical accuracy.  They consider soil structure around the site and the resonance frequencies of a wide range of structures to reduce risk further. When new hazard information becomes available, the NRC evaluates the new data and models and determines if any changes are needed at plants, so in theory plants are constantly evolving. 

Map showing the location of Nuclear power plants, given the areal extent of the US, for the most part areas of high seismic activity are avoided, the situation likely differs in Japan Source:NRC, 2012

The design flaws at Fukushima however weren't in reactor design, rather in the supporting infrastructure and flood defences surrounding the site. If Fukushima did one thing it flagged up the need to consider all components of the site. At Hinkley Point C for example construction director Nigel Cann (HazardEx, 2013) summarises that the primary modifications post-Fukushima were in elevating power supplies above ground level and building flood defences to withstand a 0.2% AEP event (equivalent to a 500 year flood event) (EDF,2011). The importance of passive features such as hydrogen recombiners which turn hydrogen into inert gas thus avoiding explosions were also highlighted (HazardEx, 2013). 

"One of the main things we learned from Fukushima was the need for hardened facilities which hasn't been a priority at UK nuclear stations up until now and to ensure we have secure control and safeguard buildings if there is an incident" Nigel Cann 

Taking into account the increasing safety and efficiency of modern reactors along with the promise of a more holistic approach to hazard assessment, investment in nuclear power is certainly looking more attractive.  However greater safety means greater cost, and I fear that regulatory standards could drop with acceleration in plant construction. Hypothetically if standards were upheld I would advocate plant construction in areas of limited seismic activity, despite its inherent risk. 

Thanks for reading! 

Fukushima Part 1- An enviro-technical disaster

In last week’s blog I came to the conclusion that nuclear energy is needed in some capacity over the coming century to cut carbon emissions, and support a gradual transition to a reliance on renewables. However whilst I affirm that combating climate change without any help from nuclear energy would be difficult if not impossible, a fully-fledged investment in atomic energy as the dominant resource is a larger commitment, which comes with higher risk.

In recent years the word ‘Fukushima’ has shadowed any commitment, withdrawal , or decision for that matter upon nuclear energy. Twenty-five years on from Chernobyl and taking place in the 3^rd largest economy in the World, it showed the vulnerability of all nations to nuclear accidents, and brought the safety and sustainability of a nuclear future to the fore.  The impacts of the event are somewhat up in the air and will very likely not be truly realised until many decades after the event. Rather than assessing the plethora of research and commentary examining the effects post-meltdown, I want to focus on whether the nuclear accident at Fukushima is better summarised as an environmental disaster, or as a 'techno-political' mistake.

The Fukushima Daiichi nuclear disaster  in March 2011 was classed a level 7 case on the Nuclear Event scale, the only other level 7 case is the Chernobyl disaster in 1986 (Source:fukushima.org)

Fukushima was a triple disaster: a magnitude 9.0 Earthquake, followed by a 14m Tsunami and the subsequent meltdown of three out of the six nuclear reactors at the Daichi Nuclear plant (Pritchard, 2012). So obviously we need cut some flack for the nuclear industry, without the magnitude 9.0 Earthquake there would have been no call for the reactors to go into emergency shutdown, therefore the self generating electricity supply would have remained on. Without a 14m tsunami ploughing into the east coast of Japan some 50 minutes later, the backup diesel generators would themselves of remained functional, pumping water to elicit the cooling of the plant’s six reactors and allowing the plant to serenely avoid a catastrophe. 

This account is perhaps the closest nuclear supporters can come to claiming a victory at Fukushima and many have. Alan Waltar, president of the American Nuclear society recently described Fukushima as ‘Nuclear’s finest hour’.  He argues that a plant designed for an 8.2 magnitude Earthquake survived an Earthquake some five times larger, the reactors shutdown and the containment stayed in tact, the only letdown was in the external power supply.

If we view the events of Fukushima as a series of isolated safety tests this isn’t far from the truth, the disaster would have almost undoubtedly been averted if the diesel generators had not been flooded. However when taking a more circumferential view of the nuclear industry, and considering characteristics inherent to nuclear energy, a different perspective on the accident may be fashioned.   

One of the specific characteristics of nuclear power, which relates very closely to Fukushima, is that nuclear reactors can never be turned off (Pritchard, 2012). A nuclear chain reaction may be stopped and the reactor is at least in theory, safely shut down, however the fuel still produces heat. This must be dissipated by continuously pumping cooled water around the reactor, fail to do so and you risk eventual meltdown:

Radioactive decay continues>more heat> boils off stationary water>water level falls>exposes fuel to steam and air>fuel damage>even greater temperature rise>>>meltdown>radioactive materials released  

The reactor cores at Fukushima were ‘safely’ shutdown a major difference from Chernobyl however heat in the reactors languished and with no electricity to ferry the shutdown reactors to safety, damage was inevitable.

Another characteristic of nuclear energy is that if an accident does happen the consequences are severe and long lasting given the very nature of the fuel being used. If a meltdown occurs and radioactive elements are able to escape into the atmosphere or surrounding waterways, they are a latent threat to the environment and human beings for many decades. Radioactive decay is random, yet enduring and consistent when scaling through time and space. 

Geigher counter measuring radiation dose rate outside the Fukushima I nuclear plant,. The half life of some components of spent nuclear fuel are short however others like Plutonium-239  have half lives in excess of 20000 years accounting for the long lasting estrangement of areas surrounding the Fukushima plant (Source: Telegraph, 2013)

When considering these inherent risks, terming Fukushima a mere accident, serves to minimize the role played by the technology being used (Perrow, 2007). After all without the tsunami there may have been no nuclear accident but without a nuclear power plant there would have been no risk in the first place. Technology of course is not self-generating and some of the blame must be attributed to the political decision by the Japanese government to back nuclear power in a country highly prone to natural hazards.

Map showing the location of Nuclear power plants (blue dots) against Earthquake activity since 1979, Japan borders a region with frequent and powerful earthquakes (red), the government turned to Nuclear energy in part due to a scarcity in natural resources such as coal and gas (Source: maptd.com)

In my opinion I don't believe a victory should be claimed for nuclear power at Fukushima, but at the same time I feel the plant's demise shouldn't be used to completely rule out future investment in the industry. I see Fukushima as a fork in the road, the extreme circumstances should be taken into consideration, but at its heart the nature of the accident is systematic of the technology being used, not extraordinary and unexpected (Perrow, 2007). With this in mind a possibilistic rather than probabilistic mindset should be adopted by the industry, and governments should consider a'worst case scenario' based on their geographical location.

In next week's blog I will look at the lessons to be learnt from Fukushima in more detail.

Thanks for reading!

Book References

Perrow, 2007 The Next Catastrophe : Reducing Our Vunerabilities to Natural , Industrial, and Terrorist Disasters, Princeton, Princeton University Press

Can we live nuclear free?

So far I have looked at two European case studies the Chernobyl disaster in 1986 and the recent proposal at Hinkley point in the UK. These have given me an idea of the health risk and current economic costs of building a nuclear power station. This week I am looking to up the anti and tackle the issue of whether a global nuclear phaseout is possible within the next century?

I ask this question in light of the growing anti-nuclear feeling across the international community since Fukushima. Phaseouts are in progress in Japan, Germany and Italy, and there has even been increased anti-nuclear sentiment in 'strongholds' such as India, and the United States (EESI,2011).  

Taking the question at face value what options do we have available if we decide to scrap nuclear power altogether?For one, in theory we could replace the energy shortfall by burning more fossil fuels. What effects might this entail and is it a risk worth taking?  
Let's take a look at some of the observed data:
.We have witnessed a 0.85C warming of the global land and ocean surface from 1880-2012 (IPCC, 2013). 
.The majority of warming has occurred in the second half of the 20th Century, where global population doubled, water use tripled and greenhouse gas emission quadrupled (Steffen et al, 2007). 
.Decadal temperatures have risen continuously since 1850 and the period from 1983-2012 was the warmest 30 year period globally of the last 1400 years (IPCC,2013). 

CO2 concentrations (in ppm) for the last 1100 years,1769 marks the date when James Watt patented the steam engine coinciding with the upshoot in CO2 Source:Mackay,2009

Still undeterred, one could argue that the post industrial temperature rise is attributable to natural variability, after all it was hotter during the Medieval warm period. It is true that some regions exhibited similar or higher temperatures to the present day, however the warming was more regional in nature. Scientists are 95% certain that humans are the dominant cause of warming since the 1950s(IPCC,2013) and the impacts of continued warming could be catastrophic. 

 Overview of the impacts of warming, unabated use of fossil fuels would likely lead to a temperature rise of over 3C by 2100 Source: Sagebrush Solar, 2013 

Based on the data shown, to replace nuclear energy's 14% share of global electricity with fossil fuels is out of the question. Not only for the sake of emissions but also sustainability. Countries, including the UK, will face an energy gap in the coming decades due to dwindling fossil fuel supplies (Mackay, 2009). Standard coal and gas powered plants need to be replaced and emissions cut significantly.Without nuclear energy is this realistic?

The answer to the question above surely depends on how much warming is deemed acceptable.  Two degrees above pre-industrial temperature is widely considered the safe amount of warming, albeit a target not without controversy. In the fifth IPCC report more ambitious mitigation scenarios were put forward (<3W/m2) partly as a response to a growing body of literature which indicated that stabilisation of radiative levels at lower levels would be needed to maintain a high probability of avoiding the 2 degree benchmark (Vuuren et al, 2013).

Step forward RCP 2.6, the lowest emission scenario where less than 2 degrees of warming is highly probable. Vuuren et al (2013) explored what it would take to follow this emission pathway. The recent study suggests that cumulative emissions of greenhouse gases would need to be reduced by 70% by 2100 relative to a baseline scenario, which itself is a lower trajectory than we are currently following! The graphs below summarise how this could be achieved.

Trends in global energy use for the baseline (left) and the mitigation scenario RCP2.6 (right) (CCS=Carbon Capture and Storage)   Source: Vuuren et al 2013

In Vuuren's analysis nuclear power is a significant contributor to global energy demand by 2100, yet it is far from dominant. It could be argued on this basis that it isn’t a necessity to reach a low emissions target.  Vuuren is assuming however that CCS and BECCS technology (see link) would allow for the continued use of cheaper fossils fuels. In reality this may not be the case, leaving a vacant energy gap. Therefore let's say we ignore the uncertain realisation of carbon capture and focus on the now. Could we rely on renewables to take the brunt of our future energy demands?

In his book Sustainable energy- Without the hot air, David Mackay(2009) stacks the energy available from renewables against current consumption for the UK. The energy gap appears only small, but taking into account the figure on the right, you begin to appreciate the dilemma faced by many developed nations in terms of adopting renewable energy.

 Consumption against estimate of energy available from renewables for the UK, measured in kWH/d per person Source: Mackay, 2009

Moving away from the UK, Germany is a country which has been able to invest heavily in renewable energy. It's share has increased from 6.3% in 2000 to 25% in 2012; and 26 billion euros of investments were made into the country's renewables market in 2010 (BMU,2012). 

However the transition has not been smooth, there have been power outages due to the variable nature of renewable sources like wind. In 2012 while renewable electricity rose by 10.2%, there was a 2% increase in emissions due to the reliance on coal as back up energy following the nuclear phaseout (Spiegel, 2013). 

Can we afford to live without nuclear power? Well considering the emission cuts needed, the lack of inertia behind sustainable living in many parts of the world, along with the price of renewable energy (Germany has the highest electricity prices in Europe), completely removing nuclear power is not workable, assuming ambitious CCS technologies are not implemented. Nuclear power could offer a carbon-free energy supply where there is a shortage of land for renewable sources and gives more time for consumption to fall and renewable energy to propagate. 

I am not sold on nuclear energy as our main energy source over the next millennia, but do believe it is needed to support a reduction in GHG emissions. 

Thanks for Reading