Measuring of Sodium Void Reactivity Effect (SVRE), one of the most important tests in China Experimental Fast Reactor (CEFR) physical start-up, is described in the paper, including test method, test results and evaluation of test results. The results met to the test requirement and the sign base of CEFR TIB Accident Special Inspect System. The calculation analysis of CEFR SVRE test has been completed, which provides data support before the test and verifies the reliability of the calculation systems after the test. The technology for analysis and measuring of SVRE in sodium-cooled fast reactor has been accumulated through the research of this test.

As one kind of fast reactor, the Traveling-Wave Reactor (TWR) utilizes depleted uranium with a small amount of enriched uranium/ plutonium which is used to kick off the chain reaction. The TWR can run for decades without refueling or removing any used fuel from the reactor. The most challenging issues on TWR are fuel design, structural material for fuel cladding, core physics process analysis and core physics design. Based on the present technology of fuel and structural material, a new concept named Standing-Wave Reactor (SWR) which is the preliminary stage of the TWR is proposed. The wave of fission would move through the depleted uranium core by fuel transfer in SWR. According to the concept of SWR and the published data of fuel and material, the R&D works on 1500MWt SWR have been performed, which cover the reactor core, reactor structure, process system et.al. The preliminary results confirm the feasibility of SWR. Meanwhile, the design of reactor core and the main systems which is based on the technologies of available pool sodium-cooled fast reactor has been accomplished.

As an important part of advanced fuel cycle R&D, conceptual study of accelerator driven system (ADS) in China started since 1995. In 2000, China Institute of Atomic Energy (CIAE), Institute of High Energy Physics (IHEP) and other institutes started a ten-year project aiming at ADS fundamental R&D on physics and related technologies, which is one item of “Key Project of Chinese National Program for Fundamental Research and Development (973 Program)” in energy domain. In order to get a better understanding of ADS neutronics characteristic, China Fast Reactor Research Center initiates a preliminary R&D program focused on neutronics design of a small lead-bismuth eutectic cooled ADS with fast spectrum. In this program, the reactor core of a 10MW thermal power ADS called CIADS (China Initiative ADS) with MOX fuel has been studied and designed. For generally concerning, CIADS can operate in either subcritical or critical mode. Different parameters, such as target size and position, position that transmutation assemblies are placed have been studied during the design work. Results show that a half size target and one zone loading can meet the needs for a small size ADS. Moreover, some important physical parameters of CIADS, such as k eff , k s , power peak factor and neutron maximum flux density are evaluated. According to the R&D work, it’s appropriate to set the k s of CIADS at 0.96∼0.98.

As the first fast reactor in China, the first criticality of CEFR (China Experimental Fast Reactor) was successfully achieved on 21 st July 2010. The first criticality test of CEFR consists of two processes: the fuel loading for net core and the criticality process. In this paper, some detailed information about this test is introduced, including methods, procedures, results, etc. The test results are compared with the theoretical analysis. Comparison shows that the test results match the theoretical analysis very well, which demonstrates that the codes utilized for theoretical analysis are capable of the basic calculation of CEFR.

Traveling wave reactor is a kind of nuclear reactor that can convert fertile material into fissile fuel as it runs using the process of nuclear transmutation. In the ignition stage of traveling wave reactor, the core performance is especially complex, since the fissile fuel and fertile material is put in different regions at the beginning. And the distribution of power density will change severely with burn-up during the reactor operation. It is an important part of the traveling wave reactor study to optimize the design of the ignition stage. In this paper, based on a two-dimensional RZ geometry model, some schemes with different sizes and compositions of the ignition zone, middle ignition zone position design and burnable neutron poison addition are simulated and analyzed. Finally, an optimized core design with multi-zone configuration and burnable neutron poison addition is shown. Some design outlines are introduced for further study.

In liquid-metal-cooled fast reactors, the temperature rise and its gradients over the core region, sometimes with an addition of the accumulated irradiation creep and swelling, result in a radial core expansion and the bowing of subassemblies, both of which lead to the radial displacements of fuel and reflector materials. In spite of the small magnitude of such displacements, the reactivity change due to radial core expansion and bowing of subassemblies during a transient, such as unprotected loss-of-flow (ULOF), is significant in magnitude and plays one of the most important roles among all inherent safety features; the focus is on the change of the power-to-flow ratio (P/F) from 1.0 to 2.0, during which a large temperature gradient is induced. A 3-D code, named PERMOV, is developed for the calculation of such reactivity feedback, at present as a part of the Neutronics Analysis System (NAS); NAS is a 3-D nodal code, independently developed by researchers in China Experimental Fast Reactor; and at the same time, the code PERMOV has a high portability, making it available to run with other mature core physics codes.