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Sugawara, Takanori; Nishihara, Kenji; Tsujimoto, Kazufumi; Kurata, Yuji; Oigawa, Hiroyuki
Proceedings of 1st International Workshop on Technology and Components of Accelerator-driven Systems (TCADS-1), p.347 - 357, 2011/06
It is supposed that the Accelerator Driven System (ADS) is safer than other critical systems such as fast reactors since the ADS is driven by the external neutron source in the subcritical state. In this study, the possibility of Core Disruptive Accident (CDA) for the ADS was investigated by detailed safety analyses. Safety analyses for Unprotected Transient Over Power (UTOP) and Unprotected Loss of Flow (ULOF) were carried out by using the SIMMER-III code. The calculation results showed that the maximum temperatures of the nitride fuel and the clad tube (316SS) in the accidents were lower than their melting points (2780
C and 1400C, respectively). It was also found by Level 1 PSA that the frequency of those accidents would be exceedingly small. Although the creep rupture of the clad tube might happen in Beam Over Power (BOP), which was a kind of UTOP, and ULOF, it was concluded that the ADS had very little possibility of CDA or the re-criticality accident.
Takei, Hayanori; Nishihara, Kenji; Tsujimoto, Kazufumi; Oigawa, Hiroyuki
Proceedings of 1st International Workshop on Technology and Components of Accelerator-driven Systems (TCADS-1), p.231 - 241, 2011/06
Frequent beam trips as experienced in existing high power proton accelerators may cause thermal fatigue problems in ADS components which may lead to degradation of their structural integrity and reduction of their lifetime. Thermal transient analyses were made on the thermal responses of four parts of the reactor components; the beam window, the cladding tube, the inner barrel and the reactor vessel. Our results indicated that the acceptable frequency of beam trips ranged from 50 to 
times per year depending on the beam trip duration. In order to consider measures to reduce the frequency of beam trips on the high power accelerator for ADS, we compared the acceptable frequency of beam trips with the operation data of existing accelerators. The result of this comparison showed that for typical conditions the beam trip frequency for durations of 10 seconds or less was within the acceptable level, while that exceeding five minutes should be reduced to about 1/30 to satisfy the acceptable level.
Tsujimoto, Kazufumi; Oigawa, Hiroyuki
Proceedings of 1st International Workshop on Technology and Components of Accelerator-driven Systems (TCADS-1), p.25 - 32, 2011/06
Atomic Energy Commission (AEC) of Japan conducted Check and Review on Partitioning and Transmutation (P&T) technology by setting up a subcommittee in 2008. The subcommittee compiled and submitted a final report in 2009. As the basic policy for R&D of P&T technologies, the report presented that the R&D of double-strata concept should be undertaken as a part of the R&D for future nuclear power generation systems considering the transitional phase from LWR cycle to FBR cycle as well as the equilibrium phase of FBR cycle. The report indicated that further R&D and the collaborations with foreign R&D activities are required for the ADS to proceed to next R&D phase where the feasibility study is to be performed from the engineering and economical viewpoints. The report also pointed out importance of the integral experiments of the transmutation systems, especially requirement of the critical experiments using MA, and importance to prepare the facility to perform these experiments.
Saito, Shigeru; Hamaguchi, Dai; Usami, Koji; Endo, Shinya; Ono, Katsuto; Matsui, Hiroki; Kikuchi, Kenji*; Kawai, Masayoshi*; Yong, D.*
Proceedings of 1st International Workshop on Technology and Components of Accelerator-driven Systems (TCADS-1) (Internet), 9 Pages, 2010/03
The research and development for an accelerator-driven system (ADS) to transmute minor actinide (MA) have been progressed. The target beam window of ADS submerged in the reactor will be subjected to high-energy proton and spallation neutron irradiation. To evaluate mechanical properties of irradiated materials, post irradiation examination (PIE) of the STIP (SINQ target irradiation program) specimens was carried out at JAEA. In the present study, PIE on austenitic steels JPCA and Alloy800H irradiated at SINQ target 4 (STIP-II) was conducted. Austenitic steels are preferable as the material for the target beam window of ADS from the view point of DBTT shift, which should be taken into consideration for ferritic / martensitic steels. The irradiation conditions were as follows: proton energy was 580 MeV, irradiation temperatures were ranged from 100 to 450C, and displacement damage levels were ranged from 6.5 to 19.5 dpa. Tensile tests were performed in air at R.T. to 350C. Results of the tensile tests performed at R.T. indicate that irradiation hardening occurred with increasing displacement damage level up to 10 dpa. At higher doses, irradiation hardening seemed to tend to saturate. Degradation of ductility was bottomed around 10 dpa and specimens kept its ductility until 19.5 dpa. All the specimens fractured in ductile manner.
Yoshida, Hiroyuki; Misawa, Takeharu; Suzuki, Takayuki*; Takase, Kazuyuki
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