말단선량계의 광자선량당량환산인자에 대한 이론적 계산

김광표,이원근,김종수,윤여창,윤석철,Kim, Kwang-Pyo,Lee, Won-Keun,Kim, Jong-Su,Yoon, Yeo-Chang,Yoon, Suk-Chul 대한방사선방어학회 1996 방사선방어학회지 Vol.21 No.1

중성자 및 전자 그리고 광자 수송코드인 MCNP 4A코드를 이 용하여 ANSI N13.32에 제안된 말단팬텀과 한국원자력연구소 제작한 말단팬텀 각각에 대하여 감마선량당량환산인자를 커마근사법에 근거하여 계산하였다. 본 계산은 $15keV{\sim}1.5MeV$ 에너지영역에 대해 단일광자에너지 선원을 고려하였으며 이러한 단일광자에너지함수로서 계산한 공기커마에 대한 선량당량의 비로서 선량당량환산인자를 이론적으로 도출하였다. 본 연구에서 이론적 방법으로 도출한 ANSI와 KAERI의 말단팬텀 각각에 대한 광자선량당량환산인자를 ANSI N13.32의 실험적 방법에 의해 제시된 값들과 비교한 결과 50keV 이상의 단일 광자에너지영역에서는 실험적 방법에 의한 값들과 최대차이 5.7% 내에서 잘 일치함을 보였다. 그러나 40 keV 이하의 에너지영역에서는 본 연구의 계산 결과가 최대 13.6%까지 낮게 평가됨을 알 수 있었으며, 이러한 차이는 낮은 에너지영역에서 두드러지는 단일에너지의 생성과 관련된 실험의 불확실성과 MCNP코드에서 모사한 Geometry의 영향에 기인하는 것으로 사료된다. In this study, the theoretical calculation of the air kerma-to-dose equivalent conversion factors was performed with a Monte Carlo N-Particle transport code for the two types of extremity phantom of the ANSI and the KAERI, respectively. Considering the distribution of absorbed dose due to the interaction of homogeneous Parallel broad beam of monoenergetic primary photons in the range between 15keV and 1.5MeV, the air kerma-to-dose equivalent conversion factors based on the kerma approximation were calculated. It is showed that all the theoretical conversion factors of the two types of the extremity phantom for the ANSI and the KAERI agree well with the experimental values of the ANSI N13.32 draft(1995) for each energy within 5.7%, maximum difference ratio, except for 13.6%, difference ratio in the case for the energy of less than 40keV. It is due to uncertainties of experiment occurred in the low X-ray energy range and geometry considered in the MCNP code.

KSTAR 토카막 장치 진공 기술 현황

김광표,김현석,Kim, Kwang-Pyo,Kim, Hyun-Seok 한국진공학회 2017 진공 이야기 Vol.4 No.1

Recently, KSTAR, Korea's superconducting fusion energy research and development device, has succeeded in driving the high performance plasma for 70 seconds for the first time in the world. Continuous plasma operation technology is an essential factor for commercialization of fusion energy power generation. Therefore, this achievement is expected to play a major role in the research of fusion technology required for future fusion power plants. In order to operate the KSTAR, the discharge process in which the neutral gas is turned into the plasma should be preceded in the start-up (breakdown) phase of tokamak operation. This process essentially involves the vacuum environment in the tokamak device. KSTAR has successfully operated a vacuum pumping system to achieve the target level of the vacuum environment through a high temperature baking operation, a discharge cleaning process and boronization.

KSTAR PFC GN<SUB>2</SUB> BAKING SYSTEM 의 최적설계와 운전결과에 관한 연구

김상태(Kim Sang Tae),김영진(Kim Young Jin),정남용(Jung Nam Yong),임동석(Im Dong Seok),김광표(Kim Kwang Pyo),방은남(Bang Eun Nam),김경민(Kim Kyung Min),김양수(Kim yang Su),권면(Kwon Myeun),유성연(Yoo Seong Yeon) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10

PFC nitrogen gas (GN<SUB>2</SUB>) baking system is a closed-loop system and consists of a compressor (nitrogen gas), a electric heater, a pre-cooler (gas vs. gas), a cooler (gas vs. water), a vacuum pump, etc. The system has the following characteristics: 1)Because the compressor cannot be operated at 350℃, the cooler is installed at its suction pipe in order to keep its suction gas temperature below 90℃; 2) The high temperature nitrogen gas fed into the PFC source an energy from compression heat of the compressor and heat retrieved of the pre-cooler to reduce the heaters capacity and those become saving operational energy highly; 3) The heater power is regulated by the temperature of the heater outlet gas through feedback control. For the heating operation in the fourth campaign, the temperature of GN<SUB>2</SUB> supplied was raised to 300℃; PFC temperature reached 250℃. This paper describes the optimum design of PFC GN<SUB>2</SUB> baking system and its operating results.

산소공급이 제한된 상태에서 자란 대장균 하이드로지나아제 동위효소 1 의 순수분리

정현순,김광표,양철학 ( Hyun Soon Jong,Kwang Pyo Kim,Chul Hak Yang ) 생화학분자생물학회 1992 BMB Reports Vol.25 No.4

The hydrogenase isoenzyme I from anaerobically grown E. coli has been purified to homogeneity. The hydrogenase isoenzyme I was solubilized from the membrane fraction by sodium deoxycholate, and purified by (NH₄)₂SO₄ precipitation, DEAE chromatography, gel filtration by Sephacryl S-300, second DEAE chromatography, and hydrophobic interaction chromatography. This isoenzyme I was purified 56-fold to a specific activity or 34.1 U/㎎ of enzyme, with a recovery of 1.35% as judged by hydrogen microevolution assay. The molecular weight of this enzyme was about 180 kDa. The hydrogenase isoenzyme I was composed of equimolar polypeptides of molecular weights 64 kDa and 30 kDa.

대장균 하이드로지나아제 동위효소의 순수분리 및 동위효소의 특성 연구

정현순,김광표,양철학 ( Hyun Soon Jong,Kwang Pyo Kim,Chul Hak Yang ) 생화학분자생물학회 1992 BMB Reports Vol.25 No.4

The hydrogenase isozyme I and II from E. coli were electrophoretically distinct. The hydrogenase isoenzyme I has been purified to homogeniety by using of non-dissociating neutral PAGE containing 0.1% (v/v) Triton X-100. The hydrogenase isoenzyme I was solubilized from the membrane fraction by sodium deoxycholate, and purified by (NH₄)₂SO₄ precipitation, DEAE chromatography, gel filtration by Sephacryl S-300, second DEAE chromatography, and hydrophobic interaction chromatography. The isoenzyme I was purified 56-fold to a specific activity of 34.1 U/㎎ of enzyme, with a recovery of 1.35% as judged by hydrogen microevolution assay. The hydrogenase isoenzyme I was a tetramer (α₂β₂) composed of equimolar polypeptides of molecular weights 64 kDa and 29 kDa. The molecular weight of this enzyme was about 180 kDa.

경수로 사용후핵연료 건식저장용기 간 중성자 표면선속 간섭률 평가

곽민우,이신동,김광표,Min Woo Kwak,Shin Dong Lee,Kwang Pyo Kim 한국방사선산업학회 2024 방사선산업학회지 Vol.18 No.2

The Korean 2^nd basic plan for management of high-level radioactive waste presented a plan to manage spent nuclear fuel through dry storage facilities in NPP on-site. For the construction and operation of the facility, it is necessary to develop the monitoring system of the integrity of spent nuclear fuel before operation. NUREG-1536 recommends that the theoretical cask array, typically in the 2×10 array, should account for shadowing effect among the dry storage casks. The objective of this study was to evaluate neutron flux accounting for shadowing effect among dry storage casks. The neutron release rate was evaluated using ORIGEN based on the design basis fuel condition. And the simulation of dry storage casks and evaluation of the shadowing effect were performed using MCNP. Shadowing effect of other dry storage casks was the highest at the center of the dry storage facility of the 2×10 array compared with the outside of the cask. The shadowing effect of neutron flux on the surface among the metal casks was approximately 18% at point 1, 23% at point 2, and 43% at point 3. For the concrete casks, the shadowing effect of neutron flux on the surface was approximately 46% at point 1, 51% at point 2, and 52% at point 3. This means that correction is necessary to monitor the integrity of spent nuclear fuel in each dry storage cask through evaluation of shadowing effect. The results of this study will be used for comparative analysis of neutron measurement data from spent nuclear fuels in dry storage cask. Additionally, the neutron flux evaluation procedure used in this study could be used as the basic data of safety assessment of dry storage cask and development of safety guide.

파이프의 고유진동수를 이용한 액체밀도측정 센서개발

장경호,이용재,김광표,안병덕 ( KYung Ho Chang,Yong jae lee,kwang Pyo kim,Byung Duk Ahn ) 한국센서학회 1995 센서학회지 Vol.4 No.3

For the development of liquid density measuring sensor using the natural frequency of a pipe, its principle and construction method were described. The stainless steel pipe, which has length of 3 cm, inside diameter of 2.3 cm and outside diameter of 2.5 cm, was used for the sensor. The exciting coil and the photo sensor were used to excite and to pick-up it, and the feedback circuit was designed to continue its vibrating. The natural frequency was consistent with the result of the spectrum analysis. It had a linearity of 0.0027 % and a sensitivity of 0.032 in liquid density range from 0.8 g/㎤ to 1.4 g/㎤ and its frequency variation ratio was 0.024 %/℃ in temperature range from 10℃ to 35℃.

국내 원자력발전소 방사선작업에 대한 피폭 분석 및 대표 고 피폭 작업 선정

이찬양,임영기,김광표,Chan Yang Lee,Young-Khi Lim,Kwang Pyo Kim 한국방사선산업학회 2024 방사선산업학회지 Vol.18 No.2

This study aims to identify high exposure tasks among the tasks performed in domestic nuclear power plants as a basis for developing training programs to improve the efficiency of workers' work. To this end, we first analyzed the exposure status of radiation work in domestic nuclear power plants. Radiation tasks in nuclear power plants were categorized, collective doses were investigated, and the collective doses were calculated based on the collective doses, and representative high exposure tasks were identified. We found that the collective and individual doses in domestic nuclear power plants are continuously decreasing, but there is an imbalance of exposure among workers. In terms of work classification, nuclear power plants are managed in 236 work codes based on light water reactors and 181 work codes based on heavy water reactors, depending on the work equipment and location. Among the total work codes, 23 codes have an annual average dose exceeding 10 μSv, and based on this, 10 representative high exposure tasks were derived. The representative high exposure tasks were selected as S/G nozzle dam work, S/G debris removal work, nuclear instrumentation system, S/G eddy current detection work, and insulation work. The results of this study are expected to serve as an important basis for reducing the exposure of workers in nuclear power plants and improving work efficiency.

건식 저장방식별 사용후핵연료 운반 작업자 피폭시나리오 개발

손건우,김혁재,이신동,곽민우,김광표,Geon Woo Son,Hyeok Jae Kim,Shin Dong Lee,Min Woo Kwak,Kwang Pyo Kim 한국방사선산업학회 2024 방사선산업학회지 Vol.18 No.1

Currently, there are no interim storage facilities and permanent disposal facilities in Korea, so all spent nuclear fuels are temporarily stored. However, the temporary storage facility is approaching saturation, and as a measure to this, the 2nd Basic Plan for the Management of High-Level Radioactive Waste presented an operation plan for dry interim storage facilities and dry temporary storage facilities on the NPP on-site. The dry storage can be operated in various ways, and to select the optimal dry storage method, the reduction of exposure for workers must be considered. Accordingly, it is necessary to develop a worker exposure scenario according to the dry storage method and evaluate and compare the radiological impact for each method. The purpose of this study is to develop an exposure scenario for workers transporting spent nuclear fuel by dry storage method. To this end, first, the operation procedure of the foreign commercial spent nuclear fuel dry storage system was analyzed based on the Final Safety Analysis Report (FSAR). 1) the concrete overpack-based system, 2) the metal overpack-based system, and 3) the vertical storage module-based system were selected for analysis. Factors were assumed that could affect the type of work (working distance, working hours, number of workers, etc.) during transportation work. Finally, the work type of the processes involved in transporting spent nuclear fuel by dry storage method was set, and an exposure scenario was developed accordingly. The concrete overpack method, the metal overpack method, and the vertical storage module method were classified into a total of 31, 9, and 23 processes, respectively. The work distance, work time, and number of workers for each process were set. The product of working hours and number of workers (Man-hour) was set high in the order of concrete overpack method, vertical storage module method, and metal overpack method, and short-range work (10 cm) was most often applied to the concrete overpack method. The results of this study are expected to be used as basic data for performing radiological comparisons of transport workers by dry storage method of spent nuclear fuel.

Effect of flow imbalance on the operational performance of the KSTAR PF superconducting magnets system

Hyunjung Lee(이현정),Jinsub Kim(김진섭),Chu Young(추용),Kwang Pyo Kim(김광표),Kabrai Park(박갑래) 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.12

A cryogenic circuit for large scaled superconducting device like a tokamak is installed quite complex. In the KSTAR tokamak, the five cryogenic circuits are managed for cooling of each components (Toroidal Field magnets, Poloidal Field magnets, structures current leads, thermal shield, buslines) independently. The circuit for the Poloidal Field magnets branches into one hundred cooling channels. Five cryogenic valves are controlling the flow rates according to cooling channel length. The KSTAR PF1 upper and lower magnets have ten cooling channels parallel respectively. The pressure drop of the magnets is adjusted by cryogenic valve and is maintained by a supercritical helium circulator. The flow rate should be uniform among the cooling channels or magnets but the flow imbalance was observed during the flow test of magnet individually. The measured imbalance was around 10 % between KSTAR PF1 upper and lower. To investigate for effect of the flow imbalance on the magnet, the simple model of the PF1 upper and lower magnets has been developed using SUPERMAGNET code. The maximum temperature trends are studied in details depending on the imbalance.