Small but perfectly formed: modular nuclear reactors

22 February 2013

While last year’s Fukushima incident may have done little to drive out mistrust concerning nuclear safety, the proposed use of small modular reactors as a safer and more efficient alternative to larger plants is starting to hold sway. Kate Jackson, chief technology officer of Westinghouse, talks to Ross Davies about how this concept could prove particularly beneficial in the BRICS nations.

In November, the recently re-elected Obama administration confirmed that it will be partially funding the design, development and commercialisation of small modular reactors (SMRs) in the US, to be staggered over the next five years. According to reports, subsidies for the initiative will be in the region of $500m.

The US Department of Energy (DOE)'s announcement indicates a shift in efforts and attitudes to the country's nuclear programme, which - it's fair to say - has not always been viewed in a favourable light.

Despite being the world's largest producer of nuclear power, no reactors have been built on US soil for over 30 years. The infamous Three Mile Island plant meltdown in Pennsylvania in 1979 - the worst accident in the country's nuclear power plant history - contributed to progress hitting the buffers in the 1980s.

Subsequently, with an evident mistrust, the US nuclear renaissance has struggled to take off as predicted. The repercussions of the Fukushima disaster in 2011 only prompted fresh safety fears and scepticism regarding the sector, not just stateside, but across the globe.

Yet, while enthusiasm for the construction of large reactors continues to dwindle, SMRs have gradually risen to the fore of debate as a safer and more cost-effective alternative - Bill Gates is a notable proponent and investor in their progress. While not entirely novel - several design concepts were mooted in the 1970s and early 1980s - their stock is consequently in ascendance.

"Around 20 years ago, the nuclear industry found itself at a kind of crossroads," says Kate Jackson, chief technology officer of Westinghouse, one of the world's largest nuclear reactor builders. "With the public more demanding over new and safer plants, some reactor vendors decided to deploy additional engineered safety systems, which were even more complex. Others, like ourselves at Westinghouse, decided to take a different approach, based on making the plant simpler."

This alternative route has been underpinned by a greater onus on passive safety design, by which the reactor does not require operator actions to shut down safely in the event of an emergency. Westinghouse is one such player to have developed an SMR, based on its benchmark AP1000 pressurised water reactor (PWR) technology, which offers simpler, safer and more efficient generation.

"The AP1000 harnesses the likes of gravity, condensation and convection to enable greater safety," explains Jackson. "Yet, it has fewer components than a typically larger nuclear reactor. It doesn't require any diesel generators, offsite power or operator interaction to be able to achieve a safe shutdown in case of an incident."

Safety first

Unveiled last year, the SMR is able to generate 225MWe and requires roughly 15 acres of land. Its main features include a pressuriser, steam generator, reactor coolant pumps, reactor vessel internals and a reactor core. Once again, security was the overriding factor taken into consideration in its design, as Jackson explains.

"Our SMR is very simple," she says. "Like the AP1000, it depends on passive technology for its safety. So, in the event of a loss of offsite power, the plant will shut down automatically without any need for human intervention or AC power for seven days. This allows for increased safety and more time for operators to be able to determine how to react."

As the name would suggest, the SMR is fully modular - another boon for many. As opposed to necessitating construction onsite, the reactor - a third of the size of a full-scale model - can be fabricated in a controlled factory setting and shipped by rail or truck. Installation is earmarked for a timeframe of 18-24 months.

"To shorten the construction time, we have modularised the plant," says Jackson. "While the AP1000 is about 30% modularised, our SMR is around 90% adaptable. This ability to build the plant so quickly also mitigates financial responsibilities as the manufacture time is drastically cut. Operators can then start generating electricity and profit very quickly."

The DOE has also discussed the possibility of installing the first SMRs on the sites of defunct and obsolete coal plants, commonly dating back to the 1950s, or those pencilled in for decommissioning. This is mainly down to SMRs having a similar generating capacity to coal plants, as Jackson explains.

"This is definitely an option, not only in the US and western Europe, but also in China and India, where there is a growing need to balance their energy portfolios and not depend entirely on coal," she says. "There is the potential to retire these old plants, which typically are in the region of 200MW, and clean their energy systems."

"Looking ahead to the sharp increase in demand forecast for the coming years, nuclear energy will represent a crucial portion of a balanced portfolio for nations. "

Jackson's mention of China and India is particularly salient give the countries' well-developed nuclear sectors. Beijing already has a long-term plan in place to increase its capacity to at least 60GW by 2020, while India, facing a potential coal shortage crisis, continues to ramp up its activities, led by Prime Minister Manmohan Singh, an outspoken yea-sayer of nuclear energy.

And, despite some well-publicised protests in the face of these moves, fearing a repeat of the Fukushima disaster, protesters continue to lobby against the Kudankulam nuclear plant, presently under construction, in India's Tamil Nadu state - SMR safety features could go some to way allaying misgivings.

Furthermore, Jackson is one of many that believe smaller reactors could make for excellent exports to more outlying areas of countries where existing grids are not strong enough to support and absorb new full-size reactors.

"Looking at a country like China, it is interested in smaller reactors for a couple of reasons," she says. "While there is a lot of demand for electricity across the entire country, naturally, this also includes smaller and more remote cities without strong electricity grids. Also, in the northern part of the country, where there is a great need for district heating, many look at SMRs as being a wonderful opportunity to combine heat and power at an affordable price."

Crossing continents

It's not just China and India that could lead the BRICS charge. Attracted by the potential of SMRs in industrial processes such as fossil fuel recovery and refinement, synthetic and biofuel production and water desalination through heat generation, Jackson cites Brazil as another country that could well support the trend in coming years, despite currently only having one operational power plant - the Angra nuclear power plant in Rio de Janeiro.

"Brazil is definitely very interested in how varied and diverse the SMR is," says Jackson. "This also goes for countries in need of seismically robust plants. As the system is submerged in a below-ground water pool, it can be isolated more easily than a larger plant with rubber pads able to dampen a quake's shock waves."

Returning to the US; while the government continues to promote and facilitate the SMR movement, vying players like Westinghouse will only to be able to start deploying reactors, both at home and abroad, once they have obtained approval from the Nuclear Regulatory Commission, which requires further spending.

Yet, in spite of possible licensing trammels, and the fact that SMRs admittedly still inhabit a theoretical rather than practical domain, there would appear to be a new wave of optimism circulating within the corridors of the nuclear industry. This is predicated on the belief that in light of rising energy consumption across the globe and the need to cut down on carbon emissions, SMRs could offer a cost-effective and safer means of bridging the gap.

"Looking ahead to the sharp increase in demand forecast for the coming years, nuclear energy will represent a crucial portion of a balanced portfolio for nations," says Jackson. "There is an opportunity for SMRs to not only facilitate that, but to also provide significant benefits through clean, reliable and flexible energy, all while driving economics in a favourable direction. So, I believe they have huge market potential."

Capital expenditure advantages aside, for most, the overriding hope is that safe SMRs can prevail and ensure that events like Fukushima are forever consigned to the past.

Kate Jackson, chief technology officer of Westinghouse.

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