Fast reactor focus: China
Entering a new era8 January 2010
As the first Chinese fast reactor nears operation, chief engineer of the China Experimental Fast Reactor project, Xu Mi gives an overview of the reactor design and how it forms the basis for the country’s future fast reactor programme.
Nine years after construction began on the China Experimental Fast Reactor near Beijing, the reactor is close to start up. First criticality is expected before the end of 2009 and the reactor is due to be connected to the grid in June of 2010.
Research on sodium-cooled fast reactor technology has been carried out in China for over forty years. From 1968 to 1988, the emphasis was on basic research: fast reactor neutronics, thermo-hydraulics, sodium technology, materials, fuels, fast reactor safety, sodium devices and instrumentation. Then in 1987, the focus shifted to applied research with an experimental fast reactor as a target. Research fields involved the study of fast reactor design, sodium technology, materials and fuels, sodium components and safety .
As the first step of the fast reactor engineering development, China decided to design and build an experimental fast reactor with a power of 65MWt and a 25MWe turbine-generator, named China Experimental Fast Reactor (CEFR). The aims of the $350 million project are: to accumulate experience on fast reactor design, construction and operation; to act as a fast neutron facility to irradiate and develop fuels and materials; and to act as a platform to test and demonstrate prototype equipment needed for fast reactors.
CEFR has been designed in order to minimise the technical-economic risks for demonstration and commercial fast reactors that will follow it. For example, the main technical selections (type of reactor, fuel handing, safety systems) have been chosen to keep consistency with prototype and commercial fast reactors. Also, the thermal parameters, non-related to reactor size are close to those of commercial fast reactors [see Table 1].
CEFR has been designed with assistance from the Russian Fast Breeder Reactor Association (R-FBR-A). There was consultancy from this organisation during preliminary (1994-1997) and detailed design phases (1998-2005).
Ordering of components for CEFR began in 1997. The components were imported mainly from Russia, France, USA and UK, with imports from abroad sharing about 30% of the total systems and components budget.
CEFR is a pool type sodium-cooled fast reactor. The fuel used for the first loading is UO2 (64.4% U-235). The primary circuit including two main pumps, four intermediate heat exchangers and reactor core is contained in a vessel (8m in diameter) containing 260t liquid sodium.
The secondary circuit is divided into two loops. Each loop is primarily composed of a sodium pump, two intermediate heat exchangers and a steam generator (evaporator and super-heater). The tertiary water steam circuit is also two loops, but the superheated steam produced (480°C; 14MPa) joins up together to drive one turbine generator.
CEFR has very strong negative feedback by temperature and power reactivity. The sodium void reactivity coefficient is also negative everywhere in the core. This means that the core has self-stability features.
The reliable removal of decay heat after reactor shut down when electricity supply is lost is important. For this reason, there are two independent passive decay heat removal systems. The decay heat is removed by natural convection and circulation of primary and secondary sodium and natural draft by air in the abovementioned accident.
The safety analysis has shown that the effective dose equivalent is less than 5mSv/accident at the boundary of the CEFR site (153m from the reactor) for any beyond design base accident (BDBA). In addition, the dose limit at the site boundary does not require short-term off-site response, which meets the safety aims proposed for Generation IV advanced nuclear energy systems. The main design parameters of CEFR are shown in Table 2.
Fast reactor strategy
China needs a huge nuclear power capacity in future. Up to 240GW – two-thirds of the world’s current capacity – is envisaged by 2050, according to a 2005 study by the Energy Area of the National High-Tech Programme.
The first phase of nuclear development is proceeding at rapid pace with deployment of PWRs. The second phase, i.e. fast reactor development, is still at its experimental stage, but the three strategic targets of fast reactor development have been proposed based on the PWR-FBR nuclear power development strategy.
Based on the decision by the government in 2006, in 2020 mainland China will have 40GWe of nuclear power plants in operation and an additional 18GWe under construction. Currently, 11 units (8.7GWe) are in operation, 17 units (16.2GWe) are under construction, with preparation for dozens more units underway. Considering the environment impacts of coal-fire plants, recent discussions have suggested doubling the target for 2020, to 80GW installed nuclear capacity.
It is impractical to meet such a large nuclear capacity with only pressurised water reactors due to limited uranium resources, especially in China. As a result almost 20 years ago the government decided on a joint PWR-FBR strategy.
In addition, faster deployment of PWRs increases the need to speed up development of FBRs and closed fuel cycle technology.
China has a three-stage fast reactor deployment strategy. The first stage of this programme (CEFR) will be followed by a demonstration fast reactor around 2020 and subsequently by larger fast breeder reactors [see Table 1].
Stage two is already underway: the pre-conceptual design of the China Demonstration Fast Reactor (CDFR) in Fujiang province was started in the 2007. Its commissioning is planned for 2018 and after that a Chinese commercial fast reactor (CCFR) type will be deployed.
The third step of fast reactor engineering development in China will be large demonstration fast breeder reactor (CDFBR) with a power of 1000-1500MWe and high breeding ratio. It is envisaged that the CDFBR will be completed in 2028 and deployed before 2035.
Commercial fast reactors should have a higher breeding ratio and shorter doubling time than experimental fast reactors. As a result the sodium cooled-metal fuel fast reactor has been selected as the main reactor type for commercial fast breeder reactors. The development of related closed fuel cycle systems will matched by China’s reactor engineering development strategy. Three strategic targets have been proposed for the future:
1. Multiple units of CDFR deployed to be in operation in 2030;
2. Nuclear capacity of 240-250GWe to be realized in 2050 mainly by FBRs;
3. Coal-fired plants to be replaced by FBRs in large scale after 2050.
China has an ambitious strategy for fast reactor technology development and therefore international cooperation with other countries is important.
 XU Mi, Fast Reactor Technology R&D Activities in China, Nuclear Engineering and Technology, Vol.39, No.3, June 2007.
XU Mi, Chief Engineer of CEFR, China Institute of Atomic Energy, Box 275 Beijing, China 102413Related ArticlesChina’s experimental fast reactor: commissioning on schedule Criticality for China’s first fast reactorFilesTables1&2