Rebirth of Nuclear Power and New Generations of Nuclear Reactors-Part of a Clean Energy Strategy

There is growing interest world-wide in the potential for nuclear energy to have a major role in reducing carbon emissions (i.e. providing clean energy) in addition the traditional benefits of nuclear energy efficiency and the ability to meet energy generation capacity requirements. Recent Gallup Inc. poll results indicate that U.S. public opinion is increasingly favorable towards nuclear power, with the percentage of the population who support its rebirth rising from 46 to 59 percent from 2001 to 2009.

Despite this increasing public (and potentially political) support for nuclear, the images of the events surrounding Three Mile Island and Chernobyl haunt the public perception of nuclear power, and remain a clear barrier to a revival in nuclear power plant construction. The nuclear industry has seized on this interest and support and has promoted several new design options to tackle the industry’s challenge of:

• Improving safety,
• Reducing energy cost, and
• Addressing the challenges related to nuclear waste.

The nomenclature for nuclear reactor designs, describing four ‘generations’, was proposed by the U.S. Department of Energy (US DOE) when it introduced the concept of Generation IV reactors.

Generation I Nuclear Power Reactors

Generation I reactors were developed in 1950-60s and none are still running today outside the United Kingdom. Some of these early reactors include the Shippingport, Magnox, Fermi 1, and Dresden plants.

Generation II Nuclear Power Reactors

Generation II reactors generally refers to the class of commercial reactors built up to the end of the 1990′s. About 85% of the world’s nuclear electricity is generated by reactors derived from designs originally developed for use by the U.S. Navy. These and other second-generation nuclear power units have been found to be safe and reliable, but they will likely be replaced by improved designs. They are known to have (rare) core damage frequencies as high as one core damage event for every 100,000 years of operation.

Generation III Nuclear Power Reactors

Generation III reactors, for which there is growing widespread interest, are the new and evolutionary designs which have been developed from the innovations created during the operating era of the Generation II reactor designs, including:

• Improved fuel technology,
• Superior thermal efficiency,
• Passive safety systems, and
• Standardized design resulting in reduced maintenance and capital costs.

These third-generation reactors incorporate passive or inherent safety features that require no active controls or operational intervention to avoid accidents in the event of malfunction, and may rely on gravity, natural convection or resistance to high temperatures; where as the traditional nuclear reactor safety systems (Generation ! and II) are ‘active,’ requiring  electrical or mechanical operation.

This improvements in nuclear reactor technology will result in a longer operational life (designed for 60 years of operation, extendable to 120+ years of operation prior to complete overhaul and RPV replacement) compared with currently used Generation II reactors (typically designed for 40 years of operation, extendable to 80+ years of operation prior to complete overhaul and RPV replacement).

Estimated core damage frequencies for these reactors are generally in the range of 1 core damage event for every 15-20 million years of operation to 1 core damage event for every 300-350 million years of operation The first generation III reactors were built in Japan, while several others have been approved for construction in Europe.

Generation IV Nuclear Power Reactors

Generation IV reactor designs are still on the drawing board and will not be operational before 2020. Numerous major international initiatives have been launched to lead the development of Generation IV nuclear reactor and nuclear fuel cycle technologies. Examples of these initiatives include:

• Generation IV International Forum (GIF) is a US-led grouping set up in 2001 that has identified six reactor concepts for further investigation with a view to commercial deployment by 2030.
• The International Atomic Energy Agency (IAEA)’s International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO) is focused more on developing country needs, and initially involved Russia rather than the USA, though the USA has now joined in. It is now funded through the IAEA budget.

Some of the Generation IV concepts have not been submitted to the U.S. Nuclear Regulatory Commission (NRC) and thus are many years away from potential approval and implementation.

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