Development of inherent reactivity control systems for fast reactors: LEM and LIM. 1. System configuration and reactor dynamics calculations

In order to provide fast reactor reactivity control systems with variety of design concept as well as maintenance free and reliable performance, the technical design of inherent reactivity control system: Lithium Expansion Module (LEM) and inherent ultimate shutdown system: Lithium Injection Module (LIM) have been conducted. The system dynamic analyses revealed that LEM and LIM are effective to provide sufficient negative reactivity feedback in UTOP and ULOF transients. Most of all, quick negative reactivity insertion of LIM can be achievable because the temperature excursion can be detected by the freeze seal placed among fuel elements at the active core top level. (author)