World Nuclear Association Blog

Onagawa: The NPP that withstood the tsunami

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A fascinating brochure has been published outlining the story of the Onagawa nuclear power plant and how it withstood the earthquake and tsunami of March 11, 2011. It is available here.

The report reviews the differences between what happened at Fukushima Daiichi, Fukushima Daini and Onagawa. 

Onagawa faced a stronger earthquake and tsunami of similar height to Fukushima Daiichi, at around 13m. The earthquake disrupted external power supplies, but with a combination of one remaining external power line and six of the eight diesel generators the plants shut down and cooling systems started as planned - in fact Unit 2 was in the process of starting up as the earthquake struck and reached cold shutdown a few minutes later.     

When the tsunami struck the damage caused to Onagawa was much less severe than at Fukushima Daiichi and Daini, because the Onagawa plant had been built at a height of 14.8m, higher than the tsunami waves. There was some disruption to unit 2 cooling, but all reactors achieved cold shutdown as planned.

The preparedness and efforts of staff at Onagawa were recognised when they were presented with a WANO (World Association of Nuclear Excellence) Award for Nuclear Excellence.

 Onagawa WANO 
Onagawa staff whose combined efforts earned them a WANO Nuclear Excellence Award 

Perhaps even more remarkable is how the Onagawa nuclear plant became a place of refuge for people from the area surrounding the plant, where many had died, and even more had been made homeless.

On March 11, 1,500 people working at the site were stranded, without any reports how their friends and family outside the plant had fared. From the devastated surrounding area 50 people sought shelter at the plant. Eventually the site would become a refuge for 364 people from the local community.

 Onagawa Refugees  

Local refugees offered shelter in Onagawa gymnasium

The article shows how robust nuclear power plants are when back up power supplies and flood defences are properly in place. Since the accident at Fukushima 'stress tests' have been carried out at reactors around the world to ensure that plants are sufficiently prepared. Even at Onagawa defences have been strengthened even more.


New WNA Report on Lifecycle Emissions from Electricity Generation

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WNA has published a new report reviewing over twenty studies of greenhouse gas emissions from electricity generation. The report concludes that the third party studies clearly show that greenhouse gas emissions from all forms of fossil fuel generation are an order of magnitude higher than those from nuclear energy and renewables.


Variation in GHG studies


Although there are variations between studies of the emissions associated with different forms of generation, by taking a mean value the following conclusions can be made:

  • Greenhouse gas emissions of nuclear power plants are among the lowest of any electricity generation method and on a lifecycle basis are comparable to wind, hydro-electricity and biomass.
  • Lifecycle emissions of natural gas generation are 15 times greater then nuclear. 
  • Lifecycle emissions of coal generation are 30 times greater then nuclear. 
  • There is strong agreement in the published studies on life cycle GHG intensities for each generation method.

The studies chosen used a range of assumptions, however they all took the approach of studying the full lifecycle emissions from all the generation types, not only those emissions directly associated with generation.

The WNA report also looks at differences between the conclusions of studies carried out by academia, government and industry. Although there were some variations, particularly in estimates of emissions from natural gas, overall there is a high degree of agreement between these three groups.


GHG studies from universities, industry and government


The full report can be download from the WNA website (Publications/WNA Reports) or by clicking WNA Greenhouse Gas Emissions Report.

Emerging Nuclear Countries and Nuclear Market in India

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WNA has published two new reports, available commercially on the WNA public site and available to WNA member companies on the WNA Members website.

Emerging Nuclear Energy Countries

Many countries that currently do not have any operating nuclear power reactors are seriously considering a nuclear power program. Published in September 2011, this WNA special report outlines the particular set of political, economic and security of supply considerations that each of the main aspiring nuclear nations faces. Online shop

Nuclear Market in India

India has a flourishing and largely indigenous nuclear power program that is expected to grow from today’s capacity of some 4,400 MWe to 20,000 MWe by 2020. The opportunities and challenges facing India’s civil nuclear power industry are presented in this WNA special report.Online shop