Fuel and fuel cycle | China
Chinese nuclear fuel1 June 2012
As a fast-developing country, China needs energy to support its development, while controlling greenhouse gas emissions. Several years ago, a policy to actively develop nuclear power was adopted, setting a goal that the installed nuclear power capacity would reach 80 GW with another 25 GW under construction by the year 2020. By Guanxing Li and Changxin Liu
Over the past three years, there were 7-8 nuclear units starting construction every year. Up to now, there are 14 nuclear units in operation and 27 units under construction in the mainland of China.
The installed nuclear capacity is 11.16 GW, accounting for 1% of the national electricity capacity, and about 2% of total generation.
On 11 March 2011, the Fukushima Daiichi Nuclear Power Station was hit by a huge earthquake and tsunami. The units were damaged badly, and there was a substantial radiological release. The accident had profound impacts on the worldwide nuclear industry, including China. The Chinese government halted new nuclear project approvals, and asked all units in operation or under construction to be completely re-assessed. There have been no new nuclear units put into construction since then. When construction will resume is not clear, but hopefully it will be before the end of 2012.
China started fuel research and design for nuclear power station in the 1980s, and now an integrated nuclear fuel R&D system has been established. The core of this system is China National Nuclear Corporation (CNNC), whose subsidiaries includes Nuclear Power Institute of China and China Institute of Atomic Energy. Other actors are China Guangdong Nuclear Power Corporation and State Nuclear Power Technology Corporation, both of which were split from CNNC some years ago.
Many test facilities have been set up, including out-of pile test facilities and in-pile test facilities. The out-of-pile test facilities are for reactor hydraulic modelling, cold and hot tests of control rod drive mechanism hydraulics, freon thermal-hydraulic tests, high-performance seismic simulations, reactor power equipment comprehensive tests, and so on. The in-pile test facilities are the High-Flux Engineering Test Reactor and the China Advanced Research Reactor.
During the R&D process for Qinshan I, the first nuclear power station on the Chinese mainland, in-pile tests of 3x3 and 4x4 sub-assemblies were carried out for demonstration and improvement.
For pool-side inspection (PSI), a test facility offers the possibility for underwater visual inspection, disassembly for irradiated sub-assemblies, rod extraction, Kr-85 leakage detection and dimensional measurement. Hot cells for post-irradiation exam (PIE) are used for dismantling and cutting, visual inspection, dimensional measurement, eddy current testing, leakage tests, gamma scanning, fission gas measurement, density tests, sampling (grinding, polishing), and metallographic testing, such as burst, tensile and toughness. The semi-hot cells for PIE are used for radiochemistry analysis, water condition control and analysis, crude deposition composition analysis, scanning electron microscope analysis, burn-up determination, and X-ray radiography.
With the above-mentioned facilities, and based on experiences from the 1980s, research and development of a China Fuel (CF) series of fuel assemblies are underway in China. CF fuel series include CF1, CF2 and CF3, with N18 and N36 Zircaloy cladding. CF1 is used in Qinshan I. CF3, with 52,000 MWd/tU burn-up, N36 cladding, and 11 spacer grids, is in the final stages of R&D. It will be put into Qinshan II reactor for testing in 2013, and will be in commercial use after 2017. CF2 may be used before CF3 is ready.
Overseas technology transfer also plays an important role in China’s fuel development. In the 1990s, the AFA series fuel assembly design and fabrication technologies were transferred from Areva of France. In the 2000s began the technology transfer of AP1000 fuel assembly from Westinghouse.
Besides the CF fuel study, there are four other activities worthy of mention: reprocessed uranium (RU) utilization, Th-based fuel utilization, TRISO fuel for High Temperature Reactor (HTR) and mixed oxide (MOX) fuel for the fast breeder reactor.
From 22 March 2010 to 30 March 2011, 24 rods of natural uranium equivalent (NUE) were tested in the CANDU reactor of Qinshan III. NUE is a mix of 70% RU and 30% depleted uranium, equivalent to 0.71% NU. The results of underwater inspection were positive. Next, some rods will be dismantled for PIE in hot cell. Hopefully, by the end of 2013, all of the fuel bundles of the Qinshan III CANDU reactor will use NUE.
Concerning the Th-based fuel utilization, nuclear grade ThO2 powder and pellets have been produced. The next step is for Th-based fuel to be manufactured and put into a research reactor for radiation tests in 2014. With low-enriched uranium as the driver, Th-based fuel could be used in the Qinshan III CANDU reactor.
A demonstration nuclear power station using high-temperature gas-cooled pebble-bed reactor technology will be constructed in China in the near future. This reactor uses TRISO fuel pebbles with 9.45% U-235, each of which is 60mm in diameter. The core will hold a total of 420,000. HTR fuel R&D works are being carried out by Tsinghua University.
The China Experimental Fast Reactor (CEFR) was connected to the grid in 2011. The first fuel core and first reload uses high-enriched uranium (64.4%). For the remaining CEFR cycles, MOX fuel manufactured in China will be used. The MOX fuel will have 97.7kg Pu, 42.6kg U with 19.6% enrichment, Cr-Ni cladding, 60,000 MWd/tU burn-up at the beginning, then 100,000 MWd/tU. Now, the MOX fuel pellet is being fabricated and will be put into irradiation tests in 2012.
In China, there are currently two fuel manufacturers: China Jianzhong Nuclear Fuel Co., Ltd. (CJNF) in Yibin, Sichuan Province and China Northern Nuclear Fuel Co., Ltd.(CNNFC), in Baotou, Inner Mongolia, both of which are CNNC subsidiaries.
At CJNF, production capacity is 600 tU/yr for PWR fuel and 200 tU/yr for VVER-1000 fuel. At CNNFC, the production capability is 200 tU/yr for CANDU-6 fuel and 200 tU/yr AFA 3G PWR fuel. Also at CNNF, two fuel manufacturing lines will be built very soon. One is a 400 tU/yr AP1000 fuel line, which was planned to provide fuel in 2014. Another one is for 300,000 TRISO pebbles/yr for HTR, which is in the final stages of design.
In 2020, the total production capability is expected to be more than 2200 tU/yr at CJNF and 1400 tU/yr at CNNFC. The present manufacturing technology is mainly transferred from overseas companies, except CF 1 technology. In the future, the technology could be domestic or international depending on the market.
Qinshan I was connected to the grid in 1991, and began commercial operation in 1994. The total number of its leaking fuel assemblies is 13, from 25 leaking rods. Most of them happened in the station’s fourth cycle in 1998, mainly because of debris fretting that damaged the bottom end of rods. After that, assembly-bottom debris filters were installed. In 2003, there were two fuel rods damaged by bad handling. During more recent cycles, no leakages have been found.
Qinshan II has operated without any leakage or other damage since its 2002 startup. There are two reasons for this performance: first, excellent management, including good quality control from material purchasing, manufacturing and operation. The second reason is that the 650 MW reactor uses 1000 MW reactor fuel assemblies.
Since Qinshan Phase III was put into operation in 2002, there have been in total 27 leaking bundles, most of them in the first three cycles and caused by debris. During the past five years, only two bundles were damaged, which is good performance compared with other PHWRs in the world.
In Tianwan, one small leaking rod was found in the centre of the unit 1 core during the first cycle. The leak was mainly due to an excess of transient tests performed before commercial operation.
In Daya Bay, there were nine fuel assembly leakages found in the early cycles, one of which was caused by bowing. After debris filters were installed, there were no more leakages, which is a good operational record.
In Ling Ao 1 two fuel assemblies (and three fuel rods) were found with leakage in 2008; one of them had more than 40,000 MWd/tU burn-up, the other was a brand-new M5 AFA3G assembly. Including Ling Ao 2, there were in total 10 incidents of spacer grid damage during refuellings.
In the Chinese mainland, the annual spent fuel production is 370 tons. In Qinshan III, a dry spent fuel storage facility has been finished and is in operation. Most of the spent fuel is stored in pools on site. Since 2003, a total of 27 containers of Daya Bay spent fuel have been transferred to a pilot plant storage facility located in Gansu Province that began operating in 2003.
If nuclear power in China maintains its rapid pace of development, there would be more than 13000 tons of accumulated spent fuel in 2020. China has adopted a policy of reprocessing. And generally speaking, the development of reprocessing has kept pace with development of fast reactors.
Now, a pilot reprocessing plant at Lanzhou, Gansu Province, has been finished. Its reprocessing capacity is 50t/yr. In 2005, CNNC initialized the work for commercial reprocessing. A commercial reprocessing plant with a storage capacity 3000-6000t and a reprocessing capacity of 800 t/yr is now in development, and hopefully will go into operation in 2025. Its design basis spent fuel is an M5-clad UO2 pellet with 4.45% enrichment and average burn-up of 45,000 MWd/tU. The commercial reprocessing plant may be built using Chinese technology or in cooperation with overseas partners.
Study of waste disposal began in 1986. In 2006, a three-step schedule was decided: disposal site R&D by 2020; deep geologic disposal laboratory finished before 2040; permanent disposal operations after 2040.
According to government requirements, from the fifth operational year of nuclear power stations, operators should be charged 2.6 cents for every kWh for fuel cycle back end, including transportation, storage, reprocessing and disposal.
Trends and direction
The average Chinese GDP is about USD 4000 per capita, which lags behind 100 countries in the world. More than 20 million Chinese people are still under the poverty line. The average per capita electricity capacity is only 0.6 kW, about half of the world average. China is still in the early phase of development, and energy is the basis for further development. We need 4.5 billion ton coal equivalent (TCE) in 2020, compared with 3.1 billion tce in 2009.
On the other hand, our top leaders declared that China will cut carbon emission intensity by 40% to 45% by 2020 compared with the 2005 level. That means that besides energy-saving and energy-efficiency improvements, we need 0.675 billion tce of non-fossil energy in 2020. While hydro will reach its maximum 0.31 billion tce, wind, solar and bio will reach more than 0.2 billion tce, the gap of 0.16 billion tce has to be filled up by nuclear power. That means there should be 70-80 GW installed nuclear power capacity in 2020.
In the next ten years, China may become the country owning the largest nuclear power station fleet in the world. In the longer term, China will promote the peaceful use of nuclear power in a three-step development strategy: thermal reactors first, then fast reactors, and finally fusion reactors. Correspondingly, China’s nuclear fuel cycle industry has also ushered in unprecedented challenges and opportunities, and is likely to become the world’s largest. Fuel supply assurance, fuel performance, and self-reliance are the three most important issues in China’s fuel industry, including having advanced and innovative nuclear fuels and fuel cycles.
Guanxing Li and Changxin Liu, Chinese Nuclear Society, P.O. Box 2125, Beijing 100822, China
This article was first published in the May 2012 issue of Nuclear Engineering International