• Journal of Radiation Protection and Research
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• 제34권2호
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• pp.77-81
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• 2009

An Area Radiation Monitoring System (ARMS) ionization chamber, which had an 11.8 L active volume, was fabricated and performance-tested at KAERI. Low leakage currents, linearities at low and high dose rates were achieved from performance tests. The correlation coefficients between the ionization currents and the dose rates are 1 at high dose rate and 0.99 at low dose rate. In this study, an integration-type ARMS ionization chamber was tested over a year for an evaluation of its long-term stability at a radioisotope (RI) repository of the Young-gwang nuclear power plant. The standard deviation of dose rate of 1 day data and over a 100-days mean value were 6.2 $\mu$R/h and 2.9 $\mu$R/h, respectively. The fabricated ARMS ionization chamber showed stable performance from the results of the long-term tests. Design and performance characteristics of the fabricated ionization chamber for the ARMS from performance-tests are also addressed.

• Journal of Radiation Protection and Research
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• 제35권1호
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• pp.21-25
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• 2010

사용후핵연료의 저장 및 이송시 핵임계 안전성 확보를 위하여 연소도를 정확히 결정할 필요가 있다. 특히, 정확한 연소도 결정을 위해서 핵연료 축방향 연소도 분포를 정확하게 측정할 필요가 있다. 본 연구에서는 사용후핵연료 제어봉 안내관에 삽입하여 축방향 감마선 선량 분포를 측정하기 위하여 이온 챔버를 개발하였다. 이온 챔버는 유도부, 가스주입부, 센서부 세 부분으로 구성되었다. 센서부 전극은 cathode와 anode 두 전극만을 가지도록 설계되었으며, 제어봉 안내관에 원할한 삽입을 위하여 guard 전극은 사용하지 않았다. 이온 챔버 내부에 불활성 기체를 충진하고 누설 전류와 포화곡선을 측정하였다. 한국원자력 연구원의 저준위 조사 시설을 이용하여 선량 변화에 따른 이온 챔버 전류 변화를 측정하여 5% 이내의 선형성을 확보하였다. 제작된 이온 챔버는 추가적인 성능 평가를 통하여 한국원자력연구원내 조사후 시험시설에 있는 사용후핵연료 집합체의 연소도분포 측정에 적용될 예정이다.

• Journal of Radiation Protection and Research
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• 제31권3호
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• pp.149-153
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• 2006

An ionization chamber is still widely used in many fields by virtue of its' simple operational characteristics and the possibility of its' various shapes. A parallel type of an ionization chamber for a steel sheet thickness measurement was designed and fabricated. High pure xenon gas, which was pressurized up to 6 atm, was chosen as a filling gas to increase the current response and sensitivity for a radiation. A high pressure gas system was also constructed. The active volume and the incident window size of the fabricated ionization chamber were $30\;cm^3\;and\;12\;cm^2$, respectively. Preliminary tests with a 25 mCi $^{241}Am$ gamma-ray source and evaluation tests in a standard X-ray field were performed. The optimal operation voltage was set from the results of the collection efficiency calculation by using an experimental two-voltage method. Linearity for a variation of the steel sheet thickness, which is the most important factor for an application during a steel sheet thickness measurement, was 0.989 in this study.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2006년도 제33회 추계학술대회 발표논문집
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• pp.134-134
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• 2006

• Journal of the Korean Physical Society
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• 제73권10호
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• pp.1466-1472
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• 2018

A key comparison has been made between the air-kerma standards of the National Institute of Metrology (NIM), China, and other Asia Pacific Metrology Programme (APMP) members in the medium-energy X-ray. This paper reviews the primary standard Free-air ionization chamber correction factor experimental method and Monte Carlo simulation method in the NIM. The experimental method and the Monte Carlo simulation method are adopted to obtain the correction factor for the medium-energy X-ray primary standard free-air ionization chamber at 100 kV, 135 kV, 180 kV, 250 kV four CCRI reference qualities. The correction factor has already been submitted to the APMP as key comparison data and the results are in good agreement with those obtained in previous studies. This study shows that the experimental method and the EGSnrc simulation method are usually used in the measurement of the correction factor. In particular, the application of the simulation methods is more common.

• 전기의세계
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• 제19권4호
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• pp.18-23
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• 1970

A neutron detector, in general, can not be utilized as the thermal neutron detecting chamber in the nuclear power reactor, especially P.W.R. due to the characteristics of high temperature, high pressure and high neutron flux in a reactor vessel. We have performed an experiment to detect the thermal neutrons at 400.deg. C and high flux of thermal neutron in a power reactor. Coating boron-10 on the aluminium plates by means of surface diffusion method at 600.deg. C for 5 hours in an electric furace, also we made a typical chamber which was compensated ionization chamber filled with free air as an ionization gas. It was checked the chamber characteristics in the TRIGA MARK-II Reactor at the power level from zero to 250KW. The chamber current showed a perfect linear increase to power increase. However, many variation of the measured current were observed within the power of 50KW.

• 한국콘텐츠학회논문지
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• 제8권11호
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• pp.203-209
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• 2008

방사선 치료분야에서 인체에 조사되는 방사선 양은 수 ${\sim}$ 수 십 Gy로 매우 높기 때문에 항상 정확히 다루어져야 한다. 본 논문의 실험을 위해 전리함(ionization chamber)이 사용되었다. 품질관리프로토콜 (quality assurance protocol) 없이 사용되는 전리함의 상태를 파악하고, 전리함의 본래 기하학적 구조가 변형되었을 때 변화된 값을 측정하였다. 지두형 전리함의 집전극 휨 정도를 알아내기 위해 방사선 투시장치와 CT 3차원 영상으로 재구성하여 휨 정도를 정량화 하였다. 그리고 기하학적 구조가 정상적인 전리함과 측정값을 비교하여 그 값의 왜곡정도를 알아보았고, 선량측정은 4MV, 10MV photon 두 종류를 같은 선량과 선량율로 하였다. 집전극이 휘어진 전리함의 흡수선량의 왜곡정도는 대략 $5.5{\sim}7.2%$ 정도 값 이었으며 에너지에 대한 차이는 거의 없었다. 본 연구를 통해 전리함의 기하학적 구조가 시간 경과, 장비의 취급 부주위 등에 따라 변형 될 수 있고, 특히 집전극의 휨 현상이 발생할 수 있다는 것을 알았다. 또한 평소에 인지하지 못하는 곳에서도 많은 왜곡과 오차를 만들어 낼 수 있다는 것을 확인 할 수 있었다.

• 대한디지털의료영상학회논문지
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• 제12권1호
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• pp.51-58
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• 2010

Ionization chambers often exhibit a stem effect, caused by interactions of radiation with air near the chamber end, or with dielectric in the chamber stem or cable. In this study measured stem effect correction factor for length of ionization chamber from medical linear accelerator recommend to with the use of stem correction method. For a model of the Farmer-type chamber, were used to calculate the beam quality correction factor. These interactions contribute to the apparent measured exposure. Additionally, it needs to consider ionization chamber use of small volume and stem effect of cable by a large field. Linear accelerator generated photons energy and increased dose repeatedly measured by using stem correction method. Stem effect was dependence of the energy and increases with photon energy conditions improved of beam quality. In conclusion, stem effect correction factor was measured within 0.4% calculated according to the exposures stem length and also supposed to determined below 1% of another stem correction method.

• 한국의학물리학회지:의학물리
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• 제9권1호
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• pp.29-35
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• 1998

There has been necessity of an air free ionization chamber using the gold-crystal-aluminium plates, henceforth called the crystal chamber. The crystal chamber formed of parallel plates is very small in size and has more response for absorbed dose of therapeutic radiation beams. The gold plate on the crystal facing the photon and electron beam acts as an intensifier of signals and crystal plate as an ionization medium respectively. Both the copper guard ring and the aluminum collecting electrode are connected to an electrometer. Using high energy photon (6, 15 MV) and electron (9, 12, 15, 18 MeV) beams, the responses of the crystal chamber are evaluated against a PTW Farmer-type chamber at a field size of 10${\times}$10cm$^2$ and 100 cm SSD. The responses of crystal chamber for therapeutic radiation electron and photon beams are greater in magnitude by several order than Farmer. The crystal chamber has good linearity without correction factor C$\_$t,p/ with respect to the signals, a reading reproduction with good accuracy and precision less than 0.5%, and has other useful functions in measuring radiation beams.

• 한국의학물리학회지:의학물리
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• 제13권2호
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• pp.69-73
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• 2002

본 연구는 제작된 평행평판형 검출기에서 두 전극간의 거리에 따른 극성효과의 정도를 확인하기 위하여 실행되었다. 개발된 전리함의 극성효과를 측정하기 위하여 평행평판형 전리함의 윗면과 아래 면의 전극에 극성을 바꾸어가며 방사선을 조사하고 그에 의하여 생성된 전하를 측정하여 두 양을 비교하였다. 실험은 두 전극간의 거리가 3, 6, 10 mm 일 때 각각의 명목상 체적이 0.9, 1.9, 3.1 cc인 평행평판형 전리함에 대하여 실행하였다. 조사된 방사선은 6, 10 MV 광자선과 4, 6, 9, 12, 16 MeV의 전자선이며, SSD는 100 cm 이었고, 조사면 크기는 광자선의 경우는 10$\times$10 ㎤ 이고 전자선의 경우는 10$\times$10 $\textrm{cm}^2$을 사용하였으며, 측정점은 최대선량점이고, 선량률은 240 MU/min 으로 하였다. 평행평판형 전리함의 극성의 변환은 평행평판형 전리함의 윗면 즉, 방사선이 입사되는 면의 전극이 (+)극을 갖고 아래 면이 (-)극을 갖는 positive와 방사선이 입사되는 면의 전극이 (-)극을 갖고 아래 면이 (+)극을 갖게 되는 negative 측정으로 시행하였다. 실험결과는 광자선의 경우는 0.5 % 이내의 극성효과를 나타냈고, 전자선의 경우는 1% 에서 3.5% 까지 나타났으며, 높은 에너지를 갖는 16 MeV 전자선의 경우가 다른 에너지의 전자선의 경우 보다 극성효과의 영향이 적음을 알 수 있다.