Tuesday, April 13, 2010

Nuclear Issues: China becomes the first to take advantage of used nuclear fuel to run atomic power plant

By Clive Banerjee
Republished courtesy of IDN-InDepth NewsAnalysis

Image: Cameco

VIENNA (IDN) – In a landmark step, China has become the first to take advantage of used nuclear fuel to run an atomic power plant, the kinds of which Canada has exported – along with the engineering expertise to build and operate them – to a number of countries including South Korea, Romania, India, Pakistan and Argentina.

If successful over a one-year trial, this practice could help China get more energy from its imported uranium and reduce stocks of highly-radioactive used nuclear fuel at the same time, according to World Nuclear News (WNN).

The Canadian-developed Candu reactor – derived from CANada Deuterium Uranium – is generically a pressurized water reactor. However, unlike other PWRs, it uses natural – that is, un-enriched – uranium as a fuel and utilizes heavy water under pressure both as a coolant and a moderator.

The first re-use of nuclear fuel in a Candu reactor started at Qinshan nuclear power plant in China in March 2010. China has two Candu reactors in operation at its Qinshan phase three plant.

"A milestone announcement was made by Candu designer Atomic Energy of Canada Ltd (AECL) yesterday that fuel bundles containing recovered uranium from used fuel had been inserted into Qinshan Phase III unit 1. Over the next six months, another 24 of the 'natural uranium equivalent' (NUE) bundles will be used in two of the reactor's fuel channels," World Nuclear News (WNN) reported on March 24.

Mainstream light-water reactors – of which nine are in operation China – use uranium fuel enriched to 3-5 percent. After spending around three years producing power in the reactor core the level of enrichment drops to nearer the natural level of about 0.7 percent and is removed.

However, this fuel is still mostly composed of unaltered uranium capable of producing power in a pressurized heavy water reactor, like AECL's Candu model. Instead of using enriched fuel, these increase reactivity in the core by employing a heavy-water neutron reflector.

According to WNN, to make this first batch of NUE fuel, Qinshan managers collaborated with AECL, the Nuclear Power Institute of China and China North Nuclear Fuel Corporation. Fuel that had previously been used was processed to recover unspent uranium and this was mixed with some depleted uranium to achieve a mix with the same overall characteristics as natural uranium.

Technical challenges in doing this included the highly-radioactive nature of the used fuel and achieving the right blend of depleted uranium and the recovered stocks still enriched up to around 1.6 percent.

The project to achieve this began in 2008 with a view to exploring the idea and "prove that it is the simplest, most cost-effective and environmentally friendly process to utilize alternative fuel sources." A report late in 2009 suggested that China should build another two Candu reactors as part of a used fuel management strategy.

A programme in South Korea has pursued similar goals for some time. Dupic – direct use of PWR fuel in Candu – envisages the used fuel pellets from PWR fuel being broken up, heated to drive off radioactive fission products and then reformed for use in Candu fuel.

Using Candu reactors in a similar way is also under investigation in Ukraine.

According to WNN, progress in demonstrating this ability will be welcome at AECL, where hopes to export new-design reactors have faded in recent years. The company's plans to license its ACR-1000 design in the UK and USA are on hold and opportunities for new build in Canada have withered since the financial crisis. Meanwhile, the future of the state-owned corporation is uncertain as it approaches a major restructuring.

AECL's chief technology officer Anthony De Vuono said the NUE fuel cycle "opens up a sustainable development path leading to an overall extension of uranium fuel resources while, at the same time, reusing spent fuel from light water reactors."

An agreement to work together on the development of low uranium consumption Candu technologies in China was signed between the AECL and the Nuclear Power Institute of China (NPIC) on January 15, 2010.

Citing the Candu reactor's low uranium consumption per terawatt-hour of electricity delivered to the grid, Zhao Hua, president of NPIC, said: "We are interested in working with AECL to jointly develop this important advantage including recycling recovered uranium from spent PWR fuel."

NPIC, based in Chengdu, is China's main base for nuclear reactor engineering research, design, testing and operation, with 3700 staff workers and over 2200 research fellows. It is affiliated to the China National Nuclear Corporation (CNNC), which has a long track record of working with AECL.

CNNC and AECL worked together to build two Candu reactors at the Qinshan Phase III power plant, also known as Qinshan units 4 and 5. The units were built on a turnkey basis, and started up in 2002 and 2003 respectively.

In September 2007, Canada, Argentina and China signed an agreement to conduct a joint study to look at potential cooperation in the design, manufacture, construction and operation of Candu nuclear power reactors on future projects in the three countries.

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