An Evaluation study of measures for prevention of Re-criticality in sodium-cooled large FBR with MOX fuel

JNC TN9400 2000-038, 98 Pages, 2000/04

JNC-TN9400-2000-038.pdf:7.49MB

As an effort in the feasibility study on commercialized Fast Breeder Reactor cycle systems, an evaluation of the measures to prevent the energetic re-criticality in sodium-cooled large MOX core, which is one of the candidates for the commercialized reactor, has been performed. The core disruptive accident analysis of Demonstration FBR showed that the fuel compaction of the molten fuel by radial motion in a large molten core pool had a potential to drive the severe super-prompt re-criticality phenomena in ULOF sequence. ln order to prevent occurrence of the energetic re-criticality, a subassembly with an inner duct and the removal of a part of LAB are suggested based on CMR (Controlled Material Relocation) concept. The objective of this study is the comparison of the effectiveness of CMR among these measures by the analysis using SIMMER-III. The molten fuel in the subassembly with inner duct flows out faster than that from other measures. The subassembly with inner duct will work effectively in preventing energetic re-criticality. Though the molten fuel in the subassembly without a part of LAB flows out a little slower, it is still one of the promising measures. However, the UAB should be also removed from the same pin to prevent the fuel re-entries into the core region due to the pressurization by FCl below the core, unless it disturbs the core performance. The effect of the axial fuel length of the center pin to CMR behavior is small, compared to the effect of the existence of UAB.

None

Numata, Kazuaki; Otani, Seiji; *; *; *; Goto, Tatsuro*

JNC TN8430 2000-001, 23 Pages, 1999/09

JNC-TN8430-2000-001.pdf:0.89MB

None

Operation and maintenance experience on the fuel handling systems and storage facilities of "MONJU", 1

; ; Yamada, Takeshi; ; ; ; Kaito, Yasuaki; ; Kotaka, Yoshinori; ; et al.

PNC TN2410 96-005, 339 Pages, 1996/03

PNC-TN2410-96-005.pdf:14.53MB

Construction of the 'Monju' fuel handling systems was completed in April, 1992. From March 1991 to August 1992, pre-commissioning tests were carried out. In December 1992, all the systems of Monju were transfered to PNC, and commissioning tests and reactor physics tests, were started. For the first time, during these physics tests, the fuel handling systems were operated for one of the commissioning tests 'Loading to Criticality', without significant problems. 168 fuel sub-assemblies were loaded into the core and the first criticality was achieved on 5th April 1994. The fuel handling systems continued in operation for the 'Loading to Full Size of the Core', power distribution test and for cleaning discharged dummy sub-assemblies. To keep these fuel handling systems working somothly and satisfactorily annual maintenance has been carried out since 1992. This paper describes the operation and maintenance experience of fuel handling systems after the pre-commissioning tests and future study items for system reliability improvement.

None

*

PNC TN9360 93-002, 116 Pages, 1993/11

PNC-TN9360-93-002.pdf:5.14MB

no abstracts in English

Advanced safety of nuclear fuels and cores-systematic approach at the fuel and core subcommittee, 4; Activity on accident tolerance fuels (ATF)

Yamashita, Shinichiro; Abe, Hiroaki*; Sato, Daiki*; Owaki, Masao*; Sakamoto, Kan*; Kusagaya, Kazuyuki*; Tsuchiya, Akiyuki*

no journal, , 

The ATF Working Group (ATF-WG), which started its activities in July 2017, has been considering safety requirements for the introduction of ATF while incorporating overseas knowledge of the United States, which is ahead of ATF development. In the ATF-WG activities, based on the safety design of the core and fuel of LWRs for power generation, we organized the concept of extracting the evaluation items necessary for ATF safety design and the importance of ATF safety. The way of thinking organized here can also be used for the research and development of ATF that are currently underway, and we are going to summarize it in a report in the future.