|Despite Fukushima nuclear power is still seen as a key player in the worldwide drive towards low-carbon electricity production, so ensuring the safe operation of both new-build and exisitng fleets is now paramount|
Safety, as anyone in the sector will tell you, has always been paramount for the nuclear industry. But just as the much heralded nuclear renaissance began to dawn, the disaster at Fukushima turned the industry on its head, prompting a full-scale global review and shining a spotlight once again on the integrity of a whole range of safety systems.
Although the very culture of safety has been put under discussion, winners have emerged in the quest to make nuclear power palatable to a sometimes concerned and cynical public.
Manufacturers of everything from alarm, data acquisition and control systems, along with providers of services such as seismic analysis and training, look set to gain from a further tightening of design criteria for new-build and retrofit safety-related hardware and software.
“The good news for nuclear is that Fukushima is unlikely to dampen world appetite for new build,” says Enguerran Ripert, a consultant at market analyst Frost & Sullivan.
“While safety will cost more as a result [of the post-Fukushima reviews], manufacturers of those new plants that are planned are confident that such an event could not happen to these third-generation nuclear installations. There are exceptions, of course, Germany being a notable one. But the only casualties are likely to be those legacy plants which are too old for retrofitting to make any commercial or economic sense. Their closures, as we’re seeing, will be accelerated.
“There will be a greater emphasis on safety, and that will benefit a whole support industry out there, especially where manufacturers are involved in backup power systems, secondary circuits, etc., but also a whole range of safety-related infrastructure. The Fukushima incident won’t significantly affect new build; the global economy is going to be a much more significant factor. Third-generation reactor designs, such as the EPR and the AP1000, are not seen to be susceptible to the same problems that occurred in Japan.”
Ripert believes it is those plants having a similar risk profile to Fukushima – and he offers the examples of Indian Point and Diablo Canyon in the US – that will bear the brunt of ongoing reviews. “There are seismic risks to consider here, and plants of that age may be deemed to be uneconomic to bring up to modern-day standards and licence reviews may prove painful.”
There is, of course, the probability that talks of merging the numerous industry regulators will result in an all-powerful body with the mandate to impose sanctions on operators who fall short of contemporary standards – a body with more clout than the International Atomic Energy Agency (IAEA). And, on a practical level, Fukushima has refocused attention on safety systems that, in Generation III reactor designs, are already robust. “Those companies active in these areas are going to clean up,” says Ripert.
Nuclear does have a future
Nuclear power generates about 15 per cent of global electricity and is one of the world’s largest sources of power after fossil fuels and hydropower. The global nuclear energy sector is currently facing tough times in view of the Japanese nuclear disaster, the worst since Chernobyl. Fukushima brought to the fore the vulnerability of nuclear plants to nature’s fury and compelled governments to review their preparations in dealing with such large-scale crisis situations. Prior to the crisis, nuclear power was presented as an ideal alternative to fossil fuels for addressing the world’s growing energy requirements.
With energy consumption expected to escalate in the future, concerns are rising about the ability of existing non-nuclear resources to address a surging demand. While established nuclear countries such as the US and UK are expected to remain the core markets for nuclear energy projects, demand is growing strongly in Asia. The nuclear power industry is expected to remain vital for the rapidly expanding economies of India and China, where electricity supply is a prerequisite for achieving targets of economic development.
The day before the Japanese earthquake hit Fukushima, there were 442 operational nuclear reactors worldwide, and another 65 under construction. As of the beginning of February 2012, the number of working plants was 435 and 63 were being built, according to the European Nuclear Society and the Nuclear Energy Institute. Overall, at least 60 countries that currently do not have nuclear power have expressed interest in pursuing it. Reactor construction is limited to a handful of Generation III designs, although the main players are supported by a large number of suppliers, many of which are active in the safety sector.
Reactor designs, largely refinements of tried and tested pressurised water reactor (PWR) technology, boast an array of safety features. Areva says its EPR, for example, has taken the existing high level of safety of PWRs to an entirely new level. Its major safety systems consist of four sub-systems or trains, each capable of performing 100 per cent of the safety function on its own. Each safety system is physically separated from the others and two of them are airplane-crash resistant. Located in separate parts of the plant, they have their own protection features, which overcome the risk of simultaneous failure of all the safety systems because of internal or external events.
This month approval was granted to build the first new nuclear power plant in the US for 30 years in Georgia, while in France, President Sarkozy wants to extend the life of the country’s nuclear fleet beyond the next 40 years. Meanwhile in the UK, Poland and the Czech Republic, plans for new nuclear plants continue apace.
Not everyone has signed up the nuclear future, however. The decision in September by Siemens, formerly a major player in the nuclear industry, to withdraw entirely from nuclear power marks a significant declaration by a corporation about nuclear power and the world’s potential energy future.
“The chapter is closed for us,” Peter Loescher, chief executive of the German engineering group, said at the time. “We are no longer going to participate in taking responsibility for building nuclear power stations or financing them.” The Siemens decision follows that of the German government to abandon nuclear power and close the nation’s 17 existing plants and instead pursue renewable energy led by solar, wind and geothermal.
The decision shows how fast the taste for nuclear power can sour. It was only two years ago that Siemens sealed a deal for a joint venture with Rosatom, Russia’s state nuclear company. Loescher pledged to become a “market leader in nuclear energy” challenging GE Hitachi Nuclear Energy, Westinghouse and Areva.
The World Association of Nuclear Operators (WANO) unites all companies and countries with operating commercial nuclear power plants to achieve the highest possible standards of nuclear safety. Its aim is to maximise the safety and reliability of nuclear power plants worldwide by working together to assess, benchmark and improve performance through mutual support, exchange of information and emulation of best practices. At the 11th WANO biennial general meeting last year the world’s nuclear operators approved a series of wide-ranging new commitments to nuclear safety. The meeting, held in Shenzhen, China, followed the most significant seven months in the nuclear industry’s recent history, after the Fukushima Daiichi disaster. Some 600 registered participants attended the meeting and pledged their support for the recommendations developed by the WANO Post-Fukushima Commission. The commission, which was established in the immediate aftermath of the accident, put forward five recommendations for discussion by the WANO governing board. The board recommended developing a worldwide integrated event response strategy, expanding the scope of WANO’s activities, boosting its credibility by changing its peer review process, and improving its transparency.
Fukushima (see panel on p.24) will cast a shadow over the industry for many years and several ongoing studies will have a profound effect on nuclear safety. An extraordinary meeting of the Contracting Parties to the Convention on Nuclear Safety (CNS) will provide an opportunity this year to consider further means to strengthen safety. This will be addressed through several measures proposed in an action plan with 12 main components, each with corresponding sub-actions, focusing on such issues as: safety assessments in the light of the accident at Fukushima; IAEA peer reviews; emergency preparedness and response; national regulatory bodies; operating organisations; IAEA safety standards; international legal framework; EU Member States planning to embark on a nuclear power programme; capacity building; protection of people and the environment from ionising radiation; communication and information dissemination; and research and development.
Achieving Safety via Software and Instrumentation
Yet nuclear remains a recognised key aspect of the global drive towards clean energy. And those within the industry stress that it is a safe and secure means of providing energy while being seen as one answer to global climate change.
|A review of the safety of UK plants last year described Sizewell B’s cooling system as “one of the world’s best” Source: WANO|
While some legacy plants are nearing the end of their useful lives, and present a difficult commercial and economic case for licence extension, many more have a brighter future. Yet even in these, control and instrumentation equipment is ageing and becoming obsolescent, representing a rising risk to power generation. The strategy for managing these issues must adequately mitigate the risks, optimising a range of approaches that include maintenance, refurbishment or complete replacement of systems, or sub-systems.
The market relies more on software and smart instrumentation than ever before. But the drive towards standardisation across old and new facilities could be compromised as existing legacy systems are not being replaced. It is here where companies such as Altran Praxis are gaining prominence.
Altran Praxis deliveres a broad range of safety engineering services, including safety case development and independent nuclear safety assessment. As the dependency on programmable systems and smart instruments grows, the company is assisting organisations with the safe integration of the latest software intensive technology. It also continues to provide safety audits and assessments to meet all relevant international safety standards. The company advises nuclear industry clients on advanced software engineering methods, exploiting extensive safety-critical system development experience from other markets.
|An operative at a nuclear facility in Canada Source: WANO|
Altran Praxis says it believes that legacy systems have a key part to play in the future of the nuclear industry and it is advising on strategy and supporting such systems. The company has recently completed an assignment at the UK’s Dungeness B nuclear power station preparing engineering change reports which gain approval for safety modifications of a statutory outage. Modifications covered the main cooling pipework, reactor vessel cooling pipework, turbine condenser cooling supply, reactor gas circulator pump lifting frame and nitrogen shutdown.
Similar support is provided by a raft of specialist companies, including Tyco Flow Control, a division of Tyco International, which was recently awarded more than $13 million in contracts from China’s State Nuclear Power Engineering Company, China Nuclear Power Engineering Company, and the China Nuclear Power Engineering Corporation to provide valves and controls for 26 new nuclear reactor projects in China.
In addition, Tyco Flow Control has recently expanded its manufacturing capabilities beyond its traditional facilities in North America and Europe. This enables the company to produce more products locally in China and other emerging markets. A portion of these newly contracted valves will be manufactured at Tyco Flow Control’s manufacturing facility in Shanghai. These products are to be used in the new reactors being constructed at the Fuqing, Tianwan, Yiangian, Fangchenggang, Sanmen and Haiyang sites in China.
China, one of the world’s leading power markets, has taken another step to expand its nuclear power infrastructure with the addition of two Areva EPRs. This marks the first time that EPR technology will be introduced to a country outside Europe. The reactors, Taishan 1 and 2, were commissioned by the Guangdong Taishan Nuclear Power Joint Venture Company, and will help China meet its goal of adding 60-70 GW of nuclear power by 2020.
It may be years before the consequences of the Fukushima crisis are fully understood. A particular nuclear scenario, fully documented by the Union of Concerned Scientists, is loss of coolant, which results in the melting of the nuclear reactor core. This phenomenon has motivated studies on both the physical and chemical possibilities, as well as the biological effects of any dispersed radioactivity that could result.
Those responsible for nuclear power technology in the West have devoted extraordinary effort to ensuring that a meltdown of the reactor core would not take place, since it was assumed that a meltdown of the core would create a major public hazard and, if uncontained, a tragic accident with likely multiple fatalities.
In avoiding such accidents the industry has been very successful, and a robust safety culture has played its part, as has a whole industry network of manufacturers and providers of services to the nuclear community. In more than 14 500 cumulative reactor-years of commercial operation in 32 countries, there have been only three major accidents at nuclear power plants, including Fukushima, the others being at Three Mile Island (1979) and Chernobyl (1986), the latter being of little relevance to reactor design outside the former Soviet bloc.
Fukushima: countdown to disaster
The Great East Japan Earthquake – to give it its official name – hit the country with magnitude 9.0 at 2.46 pm on Friday, 11 March 2011 and caused considerable damage, although the subsequent large tsunami caused very much more. The earthquake was centred 130 km offshore the city of Sendai in Miyagi prefecture on the eastern cost of Honshu Island (the main part of Japan) and was a rare and complex double earthquake giving a severe duration of about three minutes. Japan moved a few metres east and the local coastline subsided half a metre. The tsunami inundated about 560 km2 and resulted in a human death toll of more than 20 000.
Eleven reactors at four nuclear power plants in the region were operating at the time and all shut down automatically when the earthquake hit. The operating units which shutdown – Tepco’s Fukushima Daiichi 1, 2, 3; Fukushima Daini 1, 2, 3, 4; Tohoku’s Onagawa 1, 2, 3; and Japco’s Tokai – totalled 9377 MW net. Fukushima Daiichi units 4-6 – totalling 2587 MW net – were not operating at the time but were affected. Onagawa 1 briefly suffered a fire in the turbine building, but the main problem initially centred on Fukushima Daiichi units 1-3. Unit 4 became a problem on day five.
The reactors proved robust seismically, but vulnerable to the tsunami. Power, from grid or backup generators, was available to run the residual heat removal system cooling pumps at 8 of the 11 units and, despite some problems, ‘cold shutdown’ was achieved within about four days. The other three, at Fukushima Daiichi, lost power at 3.42 pm, about an hour after the quake, when almost the entire site lost the ability to maintain proper reactor cooling and water circulation functions due to being flooded by the 15-metre-high tsunami. This disabled 12 of the 13 backup generators on site, located in the basements of the turbine buildings, and also the heat exchangers for dumping reactor heat to the sea. Electrical switchgear was also disabled.
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