• Title, Summary, Keyword: reference radiation(fields)

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Intercomparison of the KAERI Reference Photon and Beta Radiation Measurements (한국원자력연구소 기준 광자 및 베타선장 측정의 국제상호비교)

  • Chang, Si-Yeong;Kim, Bong-Hwan;Kim, Jang-Lyul;McDonald, J.C.;Murphy, M.K.
    • Journal of Radiation Protection and Research
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    • v.21 no.4
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    • pp.255-262
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    • 1996
  • This paper describes the results of intercomparison measurements of KAERI reference photon and beta radiation fields between the KAERI and the PNNL(Pacific Northwest National Laboratory), recently performed at KAERI radiation calibration and dosimetry laboratory on the basis of the ANSI N13.11 criteria for personal dosimeter performance test. Each laboratory used her own radiation detectors or measurement devices traceable to her national primary standard in measuring the exposure rates for photon fields, the absorbed dose rates for beta radiation fields. The agreements in reference radiation measurements between two laboratories were found to be less than ${\pm}2.0%$ for photon fields, ${\pm}1.0%$ for beta radiation fields. Therefore, it could be concluded that KAERI reference radiation fields comply well with the international standard and thus can further serve as a national basis for the researches and developments in radiation protection dosimetry in Korea.

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CHARACTERISTICS OF THE KAERI NEUTRON REFERENCE FIELDS FOR THE CALIBRATION OF NEUTRON MONITORING INSTRUMENTS

  • Kim, Bong-Hwan;Kim, Jang-Lyul;Chang, Si-Young;Cho, Gyu-Seong
    • Journal of Radiation Protection and Research
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    • v.26 no.3
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    • pp.243-248
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    • 2001
  • Neutron reference fields of Korea Atomic Energy Research Institute (KAERI) for calibrating neutron measuring devices to be used in radiation workplace monitoring consist of two kinds of neutron spectra, the direct and the scattered neutron fields, which are produced by using radionuclide neutron sources, 252Cf and 241AmBe sources. Necessary parameters for calibration such as the anisotropy factor of each neutron source and the room-scattered fraction of some neutron surveymeters in the KAERI calibration facility were determined by calculation or measurement. Spectral measurement of scattered neutron fields were performed at each reference calibration point using a Bonner Multi-sphere Spectrometer (BMS) and the dosimetric quantities for calibration also estimated from the neutron energy spectra which were unfolded using the BUNKI code.

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Reference X-ray Irradiation System for Personal Dosimeter Testing and Calibration of Radiation Detector

  • Lee, Seung Kyu;Chang, Insu;Kim, Sang In;Lee, Jungil;Kim, Hyoungtaek;Kim, Jang-Lyul;Kim, Min Chae
    • Journal of Radiation Protection and Research
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    • v.44 no.2
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    • pp.72-78
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    • 2019
  • Background: In the calibration and testing laboratory of Korea Atomic Energy Research Institute, the old X-ray generator used for the production of reference X-ray fields was replaced with a new one. For this newly installed X-ray irradiation system, beam alignment as well as the verification of beam qualities was conducted. Materials and Methods: The existing X-ray generator, Phillips MG325, was replaced with YXLON Y.TU 320-D03 in order to generate reference X-ray fields. Theoretical calculations and Monte Carlo simulations were used to determine initial filter thickness. Beam alignment was performed in three steps to deliver a homogeneous radiation dosage to the target at different distances. Finally, the half-value layers were measured for different X-ray fields to verify beam qualities by using an ion chamber. Results and Discussion: Beam alignment was performed in three steps, and collimators and other components were arranged to maintain the uniformity of the mean air kerma rate within ${\pm}2.5%$ at the effective beam diameter of 28 cm. The beam quality was verified by using half-value layer measurement methods specified by American National Standard Institute (ANSI) N13.11-2009 and International Organization for Standardization (ISO)-4037. For each of the nine beams than can be generated by the new X-ray irradiation system, air kerma rates for X-ray fields of different beam qualifies were measured. The results showed that each air kerma rate and homogeneity coefficient of the first and second half-value layers were within ${\pm}5%$ of the recommended values in the standard documents. Conclusion: The results showed that the new X-ray irradiation system provides beam qualities that are as high as moderate beam qualities offered by National Institute of Standards and Technology in ANSI N13.11-2009 and those for narrow-spectrum series of ISO-4037.

Determination of Microdosimetric Quantities of Several Neutron Calibration Fields at KAERI

  • Kim, B.H.;Kim, J.S.;Kim, J.L.;Chang, S.Y.;Cho, G.;McDonald, J.C.
    • Journal of Radiation Protection and Research
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    • v.28 no.4
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    • pp.327-335
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    • 2003
  • The commercially available neutron survey meter, the REM500, which uses a tissue equivalent proportional counter (TEPC) and the self-constructed TEPC were used to determine the microdosimetric quantities of several neutron calibration fields at Korea Atomic Energy Research Institute (KAERI). Microdosimetric spectra, absorbed dose, dose equivalent as well as quality factor were derived and compared with several neutron fields which were produced by using the shadow objects to make neutron scattered and being used as a kind of realistic neutron calibration fields at KAERI. The response of REM500 as a function of mean energy was evaluated with these neutron fields using the counts measured and the predetermined reference value. The response of the self-made TEPC and the REM500 was compared using one of the neutron calibration filelds of a $^{252}Cf$ source. The reference quantities of scattered neutron calibration fields were determined using a Bonner Sphere (BS). The value of frequency-mean lineal energy, dose-mean lineal energy and quality factor of two $^{252}Cf$ sources (unmoderated and $D_2O$ moderated) were determined to check the differences in the reference neutron fields between KAERI and Pacific Northwest National Laboratory (PNNL, USA) and the results were in good agreement within 1%. It means that there is no big difference in dosimetric quantifies of neutron calibration fields of two laboratories.

Evaluation of Characteristics in the Reference Gamma Radiation Fields for testing of Personnel Dosimetry Performance (개인선량 평가의 성능검증을 위한 기준급 감마선장의 특성 평가)

  • Oh, Jang-Jin;Cho, Dae-Hyung;Han, Seung-Jae;Na, Seong-Ho;Lee, Dew-Hey;Lee, Byung-Soo;Jun, Jae-Shik;Chai, Ha-Seok;Yi, Chul-Young
    • Journal of Radiation Protection and Research
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    • v.23 no.4
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    • pp.229-236
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    • 1998
  • In order to establish a testing system for personnel dosimetry performance, the radiation fields from photons, beta particles and neutrons are required, in recent, Korea Institute of Nuclear Safety(KINS) established the reference radation fields except neutrons and tested a variety of their properties. As a result of the test, the reference beams were shown to meet satisfactorily not only the standards of the International Organization for Standardization(ISO), but also the standard levels of the developed countries which are intercomparable with the international traceability. This paper describes the reference beam of gamma radiation. The self-designed and established reference radiation fields were investigated and analyzed by ISO and other international standards. The secondary photon contribution and the beam uniformity of the gamma radiation field were measured and evaluated to fulfill those requirements suggested by the ISO-4037. The measured air kerma rate for the $^{137}$Cs and $^{60}$Co gamma fields was 0.1891 $\sim$ 23.4967 $\mu$Gy/s sand 0.5844 $\sim$ 15.9954 $\mu$Gy/s respectively. The uncertainty with 95 % confidence level of the measured air kerma rate was determined to be less than 2.5 % which is comparable to the international reference gamma radiation fields. It was found that the evaluated air kerma calibration factors of Exradin ionization chamber were in good agreement within 0.9 % and 0.03 % with those given by PTB and NIST, respectively. The gamma radiation fields installed at KINS can maintain traceability systems in Korea, Germany and United State.

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Development of the Graphite-Moderated Neutron Calibration Fields Using 241Am-Be Sources in JAEA-FRS

  • Nishino, Sho;Tanimura, Yoshihiko;Ebata, Yoshiaki;Yoshizawa, Michio
    • Journal of Radiation Protection and Research
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    • v.41 no.3
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    • pp.211-215
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    • 2016
  • Background: The moderated neutron calibration fields using $^{241}Am$-Be sources and a graphite moderator have been constructed at the Facility of Radiation Standard (FRS) in the Japan Atomic Energy Agency (JAEA). Materials and Methods: The neutron spectra of the fields were evaluated by the Monte-Carlo calculations and measurements using the Bonner Multi-sphere Spectrometer. Results and Discussion: The fields have continuous neutron spectra from several MeV to thermal neutron energy, with fluence-averaged energies of 0.84 MeV and 0.60 MeV. Reference values of fluence rates and ambient/personal dose equivalent rates were determined from neutron spectra by measurements. Conclusion: Currently, the fields are available for calibration or performance test of neutron measuring instruments.

Performance Evaluation of Stealth Chamber as a Novel Reference Chamber for Measuring Percentage Depth Dose and Profile of VitalBeam Linear Accelerator (VitalBeam 선형가속기의 심부선량백분율과 측방선량분포 측정을 위한 새로운 기준 전리함으로서 스텔스 전리함의 성능 평가)

  • Kim, Yon-Lae;Chung, Jin-Beom;Kang, Seong-Hee;Kang, Sang-Won;Kim, Kyeong-Hyeon;Jung, Jae-Yong;Shin, Young-Joo;Suh, Tae-Suk;Lee, Jeong-Woo
    • Journal of radiological science and technology
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    • v.41 no.3
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    • pp.201-207
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    • 2018
  • The purpose of this study is to evaluate the performance of a "stealth chamber" as a novel reference chamber for measuring percentage depth dose (PDD) and profile of 6, 8 and 10 MV photon energies. The PDD curves and dose profiles with fields ranging from $3{\times}3$ to $25{\times}25cm^2$ were acquired from measurements by using the stealth chamber and CC 13 chamber as reference chamber. All measurements were performed with Varian VitalBeam linear accelerator. In order to assess the performance of stealth chamber, PDD curves and profiles measured with stealth chamber were compared with measurement data using CC13 chamber. For PPDs measured with both chambers, the dosimetric parameters such as $d_{max}$ (depth of maximum dose), $D_{50}$ (PDD at 50 mm depth), and $D_{100}$ (PDD at 100 mm depth) were analyzed. Moreover, root mean square error (RMSE) values for profiles at $d_{max}$ and 100 mm depth were evaluated. The measured PDDs and profiles between the stealth chamber and CC13 chamber as reference detector had almost comparable. For PDDs, the evaluated dosimetric parameters were observed small difference (<1%) for all energies and field sizes, except for $d_{max}$ less than 2 mm. In addition, the difference of RMSEs for profiles at $d_{max}$ and 100 mm depth was similar for both chambers. This study confirmed that the use of stealth chamber for measuring commission beam data is a feasible as reference chamber for fields ranging from $3{\times}3$ to $20{\times}20cm^2$. Furthermore, it has an advantage with respect to measurement of the small fields (less than $3{\times}3cm^2$ field) although not performed in this study.

Development of a Web-Based Program for Cross-Calibration and Record Management of Radiation Measuring Equipment

  • Park, So Hyun;Lee, Rena;Kim, Kyubo;Ahn, Sohyun;Lim, Sangwook;Cho, Samju
    • Progress in Medical Physics
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    • v.30 no.2
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    • pp.59-63
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    • 2019
  • Purpose: To manage radiation measurement equipment, a web-based management program has been developed in this study. Materials and Methods: This program is based on a web service and Java Server Pages (JSP) and employs compatibility and accessibility. Results: The first step in the workflow has been designed to create accounts for each user or organization and to log in. The program consists of two parts: fields for listed instruments, and measurement information. The instruments for measuring radiation listed in this program are as follows: ionization chambers, survey meters, thermometers, barometers, electrometers, and phantoms. Instrument properties can be put in the recording fields and browsing for associated instruments can be performed. The main part of the program is the cross-calibration for each ion chamber. For instance, the ionization chamber to be used as a relative dosimeter can be registered by cross-calibration data with a reference chamber calibrated by an accredited laboratory. This program supports methods using the central axis transfer theory for cross-calibration for the ionization chambers. The reference and field ionization chambers were placed in a solid water phantom along the beam central axis at two different depths, and then the positions were switched. Each measured value was used for calculating the cross-calibration factor. Conclusions: Because many instruments are used and managed in radiation oncology departments, systematic, traceable recording is very important. The web-based program developed in this study is expected to be used effectively in the maintenance of radiation measurement instruments.

Development of Dose Evaluation Algorithm for Film Badge Using ISO Reference Radiations (ISO 표준방사선장을 이용한 필름배지의 선량평가 알고리즘 개발)

  • Kim, Jang-Lyul;Chang, Si-Young;Lee, Jai-Ki
    • Journal of Radiation Protection and Research
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    • v.20 no.1
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    • pp.37-44
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    • 1995
  • Since provisions on the technical criteria for personnel dosimetry was amended three years ago, several improvements in the technique of monitoring personnel doses by TLD have taken place, but for the photograpfic film as a personnel monitor, additional investigations should be carried out for its accuracy of dose estimates because of its wide use in the radiation involved industries. So, this paper describes the methods to develope dose evaluation algorithm for photographic film using ISO reference radiations by i) empirical formula, ii) degree-of-fit method, and iii) matrix approximation. These methods show a good agreement between irradiated and calculated dose within tolerance level represented in ANSI N13. 11, and can be used for the dose evaluation of X, ${\gamma}$ and/or radiation fields.

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Standard Neutron Irradiation Facility for Calibration of Radiation Protection Instruments by Radioactive Neutron Sources (방사성 중성자선원에 의한 방사선방어측정기의 교정을 위한 표준 중성자 조사장치 연구)

  • Choi, Kil-Oung;Lee, Kyung-Ju;Hwang, Sun-Tae
    • Journal of Radiation Protection and Research
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    • v.14 no.1
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    • pp.66-70
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    • 1989
  • In routine testing, the radioactive neutron sources are particularly suitable for producing standard. neutron fields. The ISO TC-85 has proposed neutron reference radiation for the calibration of neutron measuring devices used for radiation protection purposes. Radiation laboratory of KSRI has installed a standard irradiation facility using $^{252}Cf$ and $^{241}Am-Be$ sources for calibrating personal dosimeters according to the recommendations given in ISO TC-85. In this study, correction factors for calibration related to neutron scattering and anisotropy are obtained by experiments with commercial rem meter for demonstration purposes.

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