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Journal Articles

Evaluation of mean time between accidental interruptions for accelerator klystron systems based on the reliability engineering method

Takei, Hayanori; Furukawa, Kazuro*; Yano, Yoshiharu*; Ogawa, Yujiro*

Journal of Nuclear Science and Technology, 55(9), p.996 - 1008, 2018/09

 Times Cited Count:1 Percentile:21.23(Nuclear Science & Technology)

Experiences with existing high-power proton accelerators indicate that frequent beam trips are inevitable. One of the reasons for such frequent beam trips is the accidental interruption to protect accelerators against fatal failures. Generally, the failure frequency for the general machinery can be evaluated based on a reliability database for its components. On the other hand, the beam-trip frequency for the accidental interruption was not evaluated based on the reliability database because it has not yet been established. A principal reason for the lack of this reliability database is the inconsistency of data collection and analysis methods among laboratories. For example, there are at least three methods to estimate Mean Time Between accidental Interruptions (MTBI) for klystron systems. In the present study, the MTBI of the klystron systems of an electron/positron injector linac at the High Energy Accelerator Research Organization (KEK) was evaluated based on the reliability engineering method, in order to build the reliability database using the unified data collection and analysis method. As the result, the mean values of the MTBI by the traditional three methods were evaluated as 30.9, 32.0, and 50.4 hours. On the other hand, that by the reliability engineering method was evaluated as 57.3 hours, i.e., more than 1.14 times of the traditional results. Although these results are obviously different from traditional results, it appears that the present estimation based on the reliability engineering method is suitable for the MTBI of accelerator components as typified by the klystron system.

Journal Articles

Recent progress in the energy recovery linac project in Japan

Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05

Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.

JAEA Reports

Estimation of acceptable beam trip frequencies of accelerators for ADS and comparison with performances of existing accelerators

Takei, Hayanori; Nishihara, Kenji; Tsujimoto, Kazufumi; Furukawa, Kazuro*; Yano, Yoshiharu*; Ogawa, Yujiro*; Oigawa, Hiroyuki

JAEA-Research 2009-023, 114 Pages, 2009/09

JAEA-Research-2009-023.pdf:8.86MB

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 performed to investigate the effects of beam trips on the reactor components. Our results indicated that the acceptable frequency of beam trips ranged from 50 to $$2times10^{4}$$ 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 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 thermal stress conditions.

Journal Articles

Estimation of acceptable beam trip frequencies of accelerators for ADS and comparison with experimental data of accelerators

Takei, Hayanori; Nishihara, Kenji; Tsujimoto, Kazufumi; Furukawa, Kazuro*; Yano, Yoshiharu*; Ogawa, Yujiro*; Oigawa, Hiroyuki

Proceedings of International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators (CD-ROM), 9 Pages, 2009/05

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 performed to investigate the effects of beam trips on the reactor components, with the objective of formulating ADS design that had higher engineering possibilities and determining the requirements for accelerator reliability. These 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 43 to $$2.5times10^4$$ times per year depending on the beam trip duration to keep the plant availability 70%. 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 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 1/35 to satisfy the plant availability conditions.

Journal Articles

Development of digital low level rf system

Michizono, Shinichiro*; Anami, Shozo*; Katagiri, Hiroaki*; Fang, Z.*; Matsumoto, Toshihiro*; Miura, Takako*; Yano, Yoshiharu*; Yamaguchi, Seiya*; Kobayashi, Tetsuya

Kasokuki, 5(2), p.127 - 136, 2008/07

One of the biggest advantages of the digital low level rf (LLRF) system is its flexibility. Owing to the recent rapid progress in digital devices (such as ADCs and DACs) and telecommunication devices (mixers and IQ modulators), digital LLRF system for accelerators becomes popular in these 10 years. The J-PARC linac LLRF system adopted cPCI crates and FPGA based digital feedback system. After the successful operation of J-PARC linac LLRF system, we developed the STF (ILC test facility in KEK) LLRF system. The future R&D projects (ILC and ERL) are also described from the viewpoints of LLRF.

Journal Articles

Comparison of beam trip frequencies between estimation from current experimental data of accelerators and requirement from ADS transient analyses

Takei, Hayanori; Tsujimoto, Kazufumi; Ouchi, Nobuo; Oigawa, Hiroyuki; Mizumoto, Motoharu*; Furukawa, Kazuro*; Ogawa, Yujiro*; Yano, Yoshiharu*

Proceedings of 5th International Workshop on the Utilisation and Reliability of High Power Proton Accelerators (HPPA-5), p.181 - 194, 2008/04

Frequent beam trips as experienced in existing high power proton accelerators may cause thermal fatigue problems in ADS components. Thermal transient analyses were performed to investigate the effects of beam trips on the reactor components. Our results indicate that the acceptable frequency of beam trips ranges from 50 to 25,000 times per year, depending on the beam trip duration. In order to measure the effect of reducing beam trips on the high power accelerator for ADS, we compared the difference between the acceptable frequency for beam trips and the operation data of existing accelerators. The result of this comparison shows that for typical conditions the beam trip frequency for durations of 10 seconds or less is within the acceptable level, while that exceeding 10 seconds should be reduced by about 1/30 to satisfy the thermal stress conditions.

Oral presentation

Comparison of beam trip frequencies between estimation from current experimental data of accelerators and requirement from ADS

Takei, Hayanori; Tsujimoto, Kazufumi; Oigawa, Hiroyuki; Mizumoto, Motoharu*; Ogawa, Yujiro*; Furukawa, Kazuro*; Yano, Yoshiharu*

no journal, , 

no abstracts in English

Oral presentation

Estimation of acceptable beam trip frequencies of accelerators for ADS, 3; Derivation of mean time between trips of klystrons including censored events

Takei, Hayanori; Furukawa, Kazuro*; Yano, Yoshiharu*; Ogawa, Yujiro*

no journal, , 

no abstracts in English

Oral presentation

Estimation of acceptable beam trip frequencies of accelerators for ADS, 4; Consideration of the probability density function for accidental interruptions of klystrons

Takei, Hayanori; Furukawa, Kazuro*; Yano, Yoshiharu*; Ogawa, Yujiro*

no journal, , 

Experiences with existing high-power proton accelerators have shown that frequent beam trips have occurred. The reasons for occurring the beam trips may be classified into two broad categories: one is the failure and/or the repair/replacement of accelerator components, and the other is preventive interruption to protect accelerators against failures. In the former case, the beam-trip frequency can be evaluated based on a reliability database for accelerator components. On the other hand, in the latter case, the beam-trip frequency was not evaluated because the reliability database has not yet been established. A principal reason for the lack of this reliability database is the inconsistency of data collection and analysis methods among laboratories. In the present study, the probability density function that accidental interruptions occurred in the klystron system of an electron/positron injector linac at the High Energy Accelerator Research Organization (KEK) was evaluated based on the reliability engineering method, in order to build the reliability database using the uniform data collection and analysis method. As the result, the probability density function might be not the exponential distribution. As this result is obviously different from the traditional result, it is necessary to re-evaluate the probability density function of the accelerator component at other accelerator facilities by use of the present method.

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