About 470 days of operation will be possible with constant heat output 1250kWt, although the equivalent diameter and effective height of the SCR core are small, being 450mm and 420mm, respectively. Primary cooling water is naturally circulated in the reactor and maintains a certain design flow rate under conditions of up to 30-degree inclination. The SCR conceptual design, conceptual system, and principal components are shown in Figs.10.2 and 10.3, and Table 10.1, respectively. In 1999, redesigning of the core for long-term use and investigation of the safety equipment has been carried out.
10.2 Research and Development by Ship Research Institute2)
Following related work in 1998, a project titled "Studies related to the application of the system reliability analysis method GO-FLOW" aimed at establishing element technology for reliability analysis of the reactor facility to begin with the marine reactor was carried out. A reactor accident sequence identification function was examined, and an accident propagation simulator was developed. In "Studies on improvement of reliability of power supply facilities of a nuclear-powered ship," extraction of the self-sequence, which is a problem in evaluating safety, was developed for a fire in which measures to avoid simultaneous failures are considered to be insufficient. In "Studies on numerical simulation of the thermal hydrostatic behavior of a marine reactor," a secondary non-stationary thermal hydrostatic analysis code was developed in order to simulate the effect of flow fluctuations derived from the ship motion on the capacity for removing decay heat from the core. In the field of the radiation shielding, the performance of high-performance shielding material was evaluated, as was safe transportation of returned radioactive wastes; a high-performance liquid shielding material was developed, and a ceramic-type, multifunction shielding material was then developed. In addition, the effect of vertical motion on the natural-circulation cooling system was studied, and studies were implemented on utilization technology of the human integral function to the reactor plant and an autonomous, decentralized cooperative function monitoring system.
10.3 Research and Development by Other Institutes
A compact deep-sea nuclear power unit consisting of a liquid metal fast reactor (LMFR) and a closed Brayton cycle (CBC) power generator has been investigated by Japan Nuclear Cycle Development Institute (JNC). A NaK cooled reactor system used in the power unit was studied in U.S.A. for space use. In 1999, the basic conceptual design and process of emergency salvage in fatal accident were investigated3).
