Huajian Chang

Considerations for in-service inspection on pressure vessel of 200MW nuclear heating reactor

Abstract The 200MW nuclear heating reactor adopts an integrated arrangement for the primary circuit. It is designed to be operated at lower temperature and lower pressure as compared to large reactors. A steel containment serves a barricade for the reactor pressure vessel. The pressure vessel has some safety characteristics, such as low stress level, low induced integral neutron flux, and high toughness etc. Among them, the most important is its LBB behavior. Based on the safety analysis for the pressure, the requirements and procedures of in-service inspection are layed-out accordingly.

A simplified refueling scheme for nuclear heating reactor

Abstract The nuclear heating reactor is a clean energy resource with high reliability and high economic benefits. Its basic design characteristics are different from those of big reactors. Some features, such as in-pressure vessel spent fuel storage, long refueling period, etc., provide the possibility to simplify the refueling system for economic purposes. After being stored in a pressure vessel for about 15 years, the spent fuel assemblies, with very low radioactivity and decay heat capacity, may be removed from the reactor pressure vessel to a storage pool by a simplified system including a shielded flask, reactor building crane, and some auxiliary tools. It is demonstrated that this ‘dry-method’ refueling scheme is safe and reliable.

Fuel storage facilities for 200-MW nuclear heating reactor

This paper reflects the thoughts and work concerning considerations and design of 200-MW nuclear heating reactor (NHR-200) developed in Institute of Nuclear Energy Technology (INET), Tsinghua University, China. Due to the fact that the size of heating reactors is limited to the local demands which are generally smaller that the economic reasonable size as compared to those reactors for electricity production, the design of systems for NHR-200 should be specified in accordance with its design characteristics, and simplified as much as possible for economic aim. The nuclear heating reactor has a low power density in the core and that the annual generation period is only about 180 days. Therefore, the total required number of fuel bundles is rather small. Furthermore, in-vessel spent fuel storage is feasible. All these features raise the potential to simplify the fuel storage system for NHR-200. The fuel storage and inspection facilities are described.

Elastoplastic constitutive model for particle-dispersed composites accounting for interfacial damage

For establishing the constitutive law, the property of a composite material is generally described by focusing on the relation between the average stress and the average strain in multiple phases. While the interface between matrix and inclusions undergoes damage, this relation should be modified accordingly. The effects of damaged interface on the strain field in composite are considered in two ways. First, the degradation of matrix-inclusion interface makes the strain field inside inclusions no longer uniform as that of inclusions with perfectly bonded interface. Secondly, it contributes to the average strain in composite by an additional strain, which is yielded from an integration of relative displacement between matrix and inclusion over their interface. In present paper, the first part is considered by using a modified Eshelbys S-tensor. After deriving the local relative displacement distributions between matrix and inclusion at the interface, the second effect of damaged interface on the average strain can be expressed in terms of the corresponding eigenstrain, by introducing a damage-relevant tensor D, which is a fourth order tensor, and tends to zero when the interface is perfect. Both the tangential and normal discontinuities at the interface are independently modeled. The numerical results are also shown. It is found that the interface conditions of debonding and/or sliding give detrimental effects on the overall properties of composites. Thus, the establishment of the most appropriate model describing properly the meso-local phenomena.