nuclear cross sections that determine core multiplication strongly depend on core temperature (e.g., the doppler, moderator density effects etc). on the other hand, since this heat is generated by the neutron flux in the reactor core, the temperature distribution in the core will depend heavily on its neutronic behavior. fuel centerline temperature could be the limiting constraint on reactor po...

This report presents a design concept for a high-capacity decay-heat removal system for the molten-salt cooled Advanced High Temperature Reactor (AHTR) [1]. The design is closely derived from the General Electric S-PRISM reactor, which is a sodium pooltype reactor [2]. The AHTR is distinguished from the S-PRISM by its use of a hightemperature thermal blanket, shown in Fig.1, that allows the ves...

This is the third part of three paper describing accidents at Fukushima Daiichi nuclear power station as analyzed in Phase 2 OECD/NEA project “Benchmark Study Accident Nuclear Power Plant” (BSAF). In this paper, we describe accident progression unit 3. Units 1 and are discussed parts series papers. BSAF project, eight organizations from five countries (CRIEPI, IAE, JAEA NRA, Japan; IRSN France;...

Activation calculations have been performed for the LIBRA reactor. Replacing HT-9 by low activation modified HT-9 increases the activity by a factor of 2.5 at shutdown while the long term activity drops by a factor of 25. The reflector is classified as Class C low level waste when modified HT-9 is used. Using HT-9 will require deep geological burial for the LIBRA radwaste. The activity produced...

The fusion-fission hybrid system has the potential attractiveness of good safety performances and plenty of fuel compared to the fission reactor system and also easing the requirement of fusion plasma technology. It is a practical path to the early fusion application for energy production. In this paper, a fusion-driven subcritical reactor for energy multiplier, named FDS-EM, is proposed. It ca...

The neutron population in a nuclear reactor is subject to fluctuations in time and in space due to the competition of diffusion by scattering, births by fission events, and deaths by absorptions. As such, fission chains provide a prototype model for the study of spatial clustering phenomena. In order for the reactor to be operated in stationary conditions at the critical point, the population o...

The Gas-Cooled Fast Reactor (GFR) is one of the reactor concepts selected by Generation IV International Forum (GIF) for next generation innovative nuclear energy systems. It was among a group more than 100 prototypes and his commercial availability expected 2030. GFR has common goals as rest GIF advanced types: economy, safety, proliferation resistance, sustainability. Several fuel design such...

Partial depletion of the primary circuit during a postulated small break loss of coolant accident can lead to the interruption of one-phase flow natural circulation. In this case, the decay heat is removed from the core in the reflux-condenser mode. In case of the partial non-availability of the safety injection system, weakly borated condensate can accumulate in particular in the pump loop sea...

In early February 2000, primary-to-secondary tube leakage ranging from one to four gallons per day (gpd) was detected in steam generator (SG) No. 24. On February 15, 2000, while the unit was operating at 99% power, SG leakage rapidly increased from 4 gpd to greater than 75 gallons per minute (gpm). The reactor was manually tripped 13 minutes later, and the faulted steam generator was isolated o...