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Takei, Hayanori
Journal of Nuclear Science and Technology, 61(8), p.1075 - 1088, 2024/08
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)In the proton linear accelerator (linac), the proton beam is unexpectedly interrupted due to the electrical discharge originating from the radio frequency, failure of the device/equipment, or other factors. Do these beam trips occur randomly? Conventionally, it has been implicitly assumed that beam trips occur randomly. In this study, we investigated whether beam trips in the linac of the Japan Proton Accelerator Research Complex (J-PARC) occur randomly to estimate the beam trip frequency in a superconducting proton linac for an accelerator-driven nuclear transmutation system. First, the J-PARC linac was classified into five subsystems. Then, the reliability function for the operation time in each subsystem was obtained using the Kaplan--Meier estimation, a reliability engineering methods. Using this reliability function, the randomness of beam trips was examined. Analysis of five-year operational data for five subsystems of the J-PARC linac showed that beam trips occurred randomly in some subsystems. However, beam trips did not occur randomly in many subsystems of the proton linac, including the ion source and the acceleration cavity, the primary subsystems of the proton linac.
Takei, Hayanori
no journal, ,
The Japan Atomic Energy Agency is working on the research and development of an accelerator-driven nuclear transmutation system (ADS) for transmuting minor actinides. This system is a combination of a subcritical nuclear reactor and a high-power superconducting proton linear accelerator (JADS-linac). One of the challenges in developing the JADS-linac is to reduce beam trips, since components in the subcritical core can be damaged by thermal cycle fatigue due to beam trips. To avoid damage to the components of the subcritical core, the beam trip frequency of the JADS-linac must be kept below the allowable beam trip frequency (ABTF). Takei et al. evaluated the ABTF and estimated the beam trip frequency of the JADS-linac using the operational data of the J-PARC linac. The estimate was based on five years of operational data in the ion source, the radio frequency quadruple linac (RFQ) and the normal conducting acceleration cavities of the J-PARC linac. As a result, it was found that the beam trip frequency with a trip duration longer than 10 sec does not meet the ABTF. By the way, data on beam trips in the superconducting RF accelerating (SRF) cavities at the Spallation Neutron Source of the Oak Ridge National Laboratory (SNS) have been published. These data are important for estimating the beam trip frequency of the JADS-linac with the SRF cavities. In this study, the mean time between beam trips (MTBT) in the normal-conducting acceleration cavities of the J-PARC linac and the SRF cavities of the SNS linac are compared and the differences between them are discussed.
