Study of an instrumentation system for a nuclear reactor plant based on optical fiber Bragg gratings

Amemiya, Kuniaki*; Nakazawa, Masaharu*; Ariyoshi, Masahiko; Ito, Keisuke

JNC TY9400 2004-008, 52 Pages, 2004/04

JNC-TY9400-2004-008.pdf:2.65MB

A new monitoring system of nuclear reactor plants by means of optical fiber Bragg gratings (FBGs) was developed which have sensitivity in temperature, distortion and vibration. The reflective wavelength of FBGs was not influenced by gamma-ray irradiation up to 1.4MGy and by exposure to fast neutrons in excess of 10 sup14 n/cm sup2. A temperature-insensitive vibration sensing system was constructed and operated with no trouble in gamma-ray environments up to 100kGy. Furthermore, a multiple point vibration sensing system was designed and constructed. The system was successfully demonstrated on a cooling system at the "Yayoi" reactor. Thus, we tried to apply the monitoring system to a primary loop area of JOYO to confirm the applicability of FBG sensors for the commercial power reactors. Although a correlation of sodium flow in side pipes and vibration measured by FBG sensors was found before starting of the reactor, it became impossible after starting operation of the reactor because of a decline of signal amplitude. Investigating the reason, it was mainly caused by significant transmission losses at the splicing point and there were no problems with FBG sensors. Various methods, for example, using a more powerful light source and changing the splicing method, may be used to improve it in the future.

High-counting-rate and high-position-resolution neutron imaging detectors using short-lifetime phosphors with crossed-fiber readout

Katagiri, Masaki; Sakasai, Kaoru; Matsubayashi, Masahito; Takahashi, Hiroyuki*; Nakazawa, Masaharu*

Nuclear Instruments and Methods in Physics Research A, 513(1-2), p.374 - 378, 2003/11

https://doi.org/10.1016/j.nima.2003.08.065

no abstracts in English

High counting rate two-dimensional neutron imaging method using rectangular scintillators with WLS fibers

To, Kentaro; Katagiri, Masaki; Sakasai, Kaoru; Matsubayashi, Masahito; Birumachi, Atsushi; Takahashi, Hiroyuki*; Nakazawa, Masaharu*

Applied Physics A, 74(Suppl.1), p.S1601 - S1603, 2002/12

https://doi.org/10.1007/s003390201834

no abstracts in English

Two-dimensional neutron imaging method using scintillators with wavelength shifting fibers

To, Kentaro; Katagiri, Masaki; Sakasai, Kaoru; Matsubayashi, Masahito; Birumachi, Atsushi; Takahashi, Hiroyuki*; Nakazawa, Masaharu*

Nuclear Instruments and Methods in Physics Research A, 485(3), p.571 - 575, 2002/09

https://doi.org/10.1016/S0168-9002(01)02072-1

no abstracts in English

High-speed readout method using wavelength-shifting fibers for an imaging plate

Katagiri, Masaki; Sakasai, Kaoru; Kishimoto, Maki; Nakamura, Tatsuya; To, Kentaro; Takahashi, Hiroyuki*; Nakazawa, Masaharu*

Nuclear Instruments and Methods in Physics Research A, 477(1-3), p.179 - 183, 2002/03

https://doi.org/10.1016/S0168-9002(01)01888-5

no abstracts in English

JENDL Dosimetry File 99 (JENDL/D-99)

Kobayashi, Katsuhei*; Iguchi, Tetsuo*; Iwasaki, Shin*; Aoyama, Takafumi*; Shimakawa, Satoshi; Ikeda, Yujiro; Odano, Naoteru; Sakurai, Kiyoshi; Shibata, Keiichi; Nakagawa, Tsuneo; et al.

JAERI 1344, 133 Pages, 2002/01

JAERI-1344.pdf:7.59MB

The JENDL Dosimetry File 99 (JENDL/D-99) has been prepared for determinations of neutron flux/fluence and energy spectrum at specific neutron fields. This file contains data for 67 reactions with 47 nuclides. Cross sections for 33 major dosimetry reactions and their covariance data were simultaneously generated and the other 34 reaction data were mainly adopted from the first version, JENDL/D-91. The GMA code was mainly used for most of the evaluation procedures by referring the basic experimental data in EXFOR. The resultant data are given in the neutron energy region below 20 MeV in both of point-wise and group-wise files in the ENDF-6 format. In order to confirm reliability of the data, several integral tests have been carried out: comparison with the data in IRDF-90V2 and average cross sections measured in fission neutron fields, fast/thermal reactor spectra, DT neutron fields and Li(d,n) neutron fields. The contents of JENDL/D-99 and the results of the integral tests are described in this report. All of the dosimetry cross sections are shown in a graphical form in the Appendix.

Positive utilization; Excess quasiparticle injection in superconducting tunnel junction X-ray detector with quasiparticle trapping layers

Nakamura, Tatsuya; Katagiri, Masaki; Okubo, Masataka*; Pressler, H.*; Takahashi, Hiroyuki*; Nakazawa, Masaharu*

AIP Conference Proceedings 605, p.173 - 176, 2002/00

https://doi.org/10.1063/1.1457622

Periodical distribution of charge output in superconducting tunnel junction (STJ) having a structure of Nb/Al/AlO/Al/Nb with size of 200 x 200 was first observed by Low Temperature Scanning Synchrotron Microscope experiments. Two swelled parts were appeared in the distribution of charge output and the period of the swelled parts was about 100. It is found that this distribution was occurred under the conditions; (1) the size of the STJ is more than twice of Josephson characteristic length and (2) a bias voltage applied to the device is more than 0.2mV of about the energy gap of the trapping layers. It was confirmed that this anomalous distribution of charge output significantly distorts the shape of the photo peak and degrades the energy resolution of the STJ detector.

Characteristics of a SrBPO:Eu storage phosphor for neutron imaging

Sakasai, Kaoru; Katagiri, Masaki; To, Kentaro; Takahashi, Hiroyuki*; Nakazawa, Masaharu*; Kondo, Yasuhiro*

Denki Gakkai Genshiryoku Kenkyukai Shiryo (NE-01-8), p.41 - 46, 2001/09

A phosphor material such as SrBPO:Eu has been investigated for two-dimensional imaging for pulsed-neutron source. The authors found this phosphor itself shows photostimulated luminescence (PSL) by illumination of 635 nm laser light after neutron irradiation without adding any neutron sensitive materials such as Gd. The PSL intensity per neutron flux was proportional to E, where E is neutron energy. The neutron sensitivity was increased by using enriched boron instead of natural boron. The S/S ratio of this phosphor using enriched boron was better than that of a commercially available imaging plate, where S and S are gamma and neutron sensitivities, respectively.

Real-time readout method of an imaging plate using wavelength-shifting fibers and a streak camera

Katagiri, Masaki; Sakasai, Kaoru; Nakamura, Tatsuya; To, Kentaro; Takahashi, Hiroyuki*; Nakazawa, Masaharu*

Nuclear Instruments and Methods in Physics Research A, 461(1-3), p.207 - 209, 2001/04

https://doi.org/10.1016/S0168-9002(00)01208-0

no abstracts in English

A Large area neutron imaging method using rectangular scintillators with WLS fibers

To, Kentaro; Katagiri, Masaki; Sakasai, Kaoru; Nakamura, Tatsuya; Matsubayashi, Masahito; Takahashi, Hiroyuki*; Nakazawa, Masaharu*

JAERI-Conf 2001-002, p.627 - 638, 2001/03

https://jopss.jaea.go.jp/pdfdata/JAERI-Conf-2001-002-Part1.pdf

no abstracts in English