중수로 원전 종사자의 방사선량 평가를 위한 $^{14}C$ 인체대사모델 분석

김희근,이형석,하각현,Kim, Hee-Geun,Lee, Hyung-Seok,Ha, Gak-Hyun 대한방사선방어학회 2003 방사선방어학회지 Vol.28 No.3

$^{14}C$은 중수로원전에서 연돌(Stack)을 통해 방출되는 중요한 방사성 핵종중의 하나로, 대략 95% 가량이 이산화탄소의 형태로 발생되고 방출되고 있다. 방사성탄소는 발생에너지가 낮은 베타 방출체로서 외부피폭은 크게 영향을 미치지 않는다. 따라서 중수로에서 탄소는 흡입이나 섭취를 통해 작업자 체내로 유입되는 경우에만 내부피폭을 일으키고 있다. 일반적으로 탄소는 신체에서 불활성 기체와 같은 거동을 보이기 때문에 섭취경로에 의한 피폭이 흡입경로에 의한 피폭보다 훨씬 높은 것으로 알려져 있다. 따라서 작업장에서 탄소의 흡입에 의한 방사선 피폭은 거의 일어나지 않으나 캐나다 원전의 압력관 교체 작업시 아주 소량의 피폭을 일으킨 경험이 있다. 본 논문은 원전 작업장에서 일어날 수 있는 방사성탄소의 흡입에 대비하여 방사선 피폭평가를 위한 방사선방호 프로그램을 수립할 목적으로 방사성탄소의 인체 대사모델 등에 대한 분석을 수행하였다. Carbon-14 is one of the major radionuclides released by CANDU Nuclear Power Plants(NPPs). It is almost always emitted as gas through the stack. From CANDU NPPs about 95% of all carbon-14 is released as carbon dioxide. Carbon-14 is a low energy beta emitter which, therefore, gives only a small skin dose from external radiation. As carbon dioxide Is physiologically rather inert gases for man's metabolism, the inhalation dose is probably less than 1 % of the ingestion dose. But this source of carbon-14, formed in a closed, nor-oxidative environment, was subsequently released into the workplace as an insoluble particulate when these systems were opened lip for re-tubing at CANDU NPPs. As a part of the improvement of dosimetry program at Wolsong Nuclear Power Plants, the carbon-14 metabolism based on references was investigated and studied to setup the internal dosimetry program due to inhalation of carbon-14.

CF8M 스테인리스 강 저주기 환경피로 실험의 주기적 변형률 경화 특성

정일석(Ill-Seok Jeong),하각현(Gak-hyun Ha),김태룡(Tae-Ryong Kim),전현익(Hyun-Ik Jeon),김영신 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5

Low-cycle environmental fatigue tests of cast austenitic stainless steel CF8M at the condition of fatigue strain rate 0.04%/sec were conducted at the pressure and temperature, 15MPa, 315℃ of a operating pressurized water reactor. The used test rig was limited to install an extensometer at the gauge length of the cylindrical fatigue specimen inside the small autoclave. So the magnet type LVDT’s were used to measure the fatigue displacement at the specimen shoulders inside the high temperature and high pressure water autoclave. However, the displacement and strain measured at the specimen shoulders is different from the one at the gauge length for the geometry and the cyclic strain hardening effect. FEM calculated the displacement and the strain of the gauge length from the data measured at the shoulders. Tensile test properties in elastic and plastic behavior of CF8M material were used in the FEM analysis. A series of low cycle fatigue tests simulating the cyclic strain hardening effect verified that the FEM calculation was well agreed with the simulated tests. The process and method developed in this study would be so useful to produce reliable environmental fatigue curves of CF8M stainless steel in pressurized water reactors.

CF8M 스테인리스 강 저주기 환경피로 실험의 주기적 변형률 경화 특성

정일석(Il-Seok Jeong),하각현(Gak-hyun Ha),김태룡(Tae-Ryong Kim),전현익(Hyun-Ik Jeon) 대한기계학회 2008 大韓機械學會論文集A Vol.32 No.2

Low-cycle environmental fatigue tests of cast austenitic stainless steel CF8M at the condition of fatigue strain rate 0.04%/sec were conducted at the pressure and temperature, 15MPa, 315℃ of a operating pressurized water reactor (PWR). The used test rig was limited to install an extensometer at the gauge length of the cylindrical fatigue specimen inside a small autoclave. So the magnet type LVDT's were used to measure the fatigue displacement at the specimen shoulders inside the high temperature and high pressure water autoclave. However, the displacement and strain measured at the specimen shoulders is different from the one at the gauge length for the geometry and the cyclic strain hardening effect. Displacement of the fatigue specimen gauge length calculated by FEM (finite element method) used to modify the measured displacement and fatigue life at the shoulders. A series of low cycle fatigue life tests in air and PWR conditions simulating the cyclic strain hardening effect verified that the FEM modified fatigue life was well agreed with the simulating test results. The process and method developed in this study for the environmental fatigue test inside the small sized autoclave would be so useful to produce reliable environmental fatigue curves of CF8M stainless steel in pressurized water reactors.

변형률속도가 CF8M CASS 환경피로 수명에 미치는 영향 평가

정일석(Ill-Seok Jeong),하각현(Gak-Hyun Ha),전현익(Hyun-Ik Jeon) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5

The Environmental fatigue life of CF8M cast stainless steel is influenced by mechanical, environmental and metallurgical parameters, such as strain rate, strain amplitude, temperature, dissolved oxygen concentration, water flow rate and so on. In an actual plant, the mechanical and environmental parameters are changing during the plant operation. Therefore, the effect of such mechanical and environmental parameter changes on fatigue life evaluation have to be studied. Low cycle fatigue life of structural materials diminishes remarkably as functions of various parameters in high temperature and high pressure environments. Such reduction can be estimated by the fatigue life reduction factor(Fen). In this study, fatigue tests were performed under changing conditions of strain amplitude, strain rate. Fatigue life was measured in terms of the number of cycles with the variation of strain amplitudes at 0.004 %/s strain rate, and the fatigue life correction factor was evaluated according to the equation modified by U. S. Nuclear Regulatory Commission(U.S.NRC) and Japanese Environmental Fatigue Tests committee(JEFT).

고온고압 환경피로실험 오토클래이브 내부용 미소변위 측정장치 개발

정일석(Ill-Seok Jeong),하각현(Gak-hyun Ha),김태룡(Tae-Ryong Kim),전현익(Hyun-Ik Jeon),김영신(Young-Sin Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

An extensometer system to measure strain and displacement of cylindrical fatigue specimen in a autoclave of high temperature and high pressure environment has been developed by KEPRI. The extensometer reads the displacement caused by fatigue loads at the target length of the specimen installed inside the autoclave. The performance of the extensometer were tested at 15㎫, 315℃of a operating pressurized water reactor. Two LVDT’s of magnet type were connected to the extensometer and used for converting the fatigue displacement to electronic signal. The device is being used for developing environmental fatigue curve of CF8M cast austenitic stainless steel (CASS) in the test condition of low cycle and low strain. This paper introduces the background and results of the development.

고온고압수에서 저주기 피로시험편의 표점거리 변위측정을 위한 장치개발

정일석(Ill-Seok Jeong),하각현(Gak-Hyun Ha),김태룡(Tae-Ryong Kim),조선영(Sun-Young Cho),전현익(Hyun-Ik Jeon),김영신(Young-Sin Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5

Low cycle fatigue experiment in high temperature and high pressure water have been conducted to evaluate environmental fatigue characteristics of nuclear materials which are used in the primary water. The experimental methods of evaluating low cycle fatigue properties are to control by either load or displacement. The study is about the development of extensometer system for measuring displacement in gauge length of low cycle fatigue specimen in autoclave which simulated high temperature and high pressure water. The developed extensometer system showed precise change of displacement data by controlling actuator in room temperature as well as high temperature and high pressure water. This device can be applied to various material testings in high temperature and high pressure environments and is expected to greatly contribute on acquiring more detailed test data.

고온고압 환경에서의 시편 표점거리에 대한 직접적 변형량 계측을 위한 분리형 변위계측장치 개발

조선영(Sun-Young Cho),정일석(Ill-Seok Jeong),하각현(Gak-Hyun Ha),전현익(Hyun-Ik Jeon),김영신(Young-Sin Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5

Environmental fatigue test is conducted in high temperature and high pressure water environment to simulate the environment of operating nuclear power plant. In addition, FEM(finite element method) and direct strain measurement method have been used to measure the strain of specimen in a closed system. This study has developed a separated typed extensometer system that can directly measure the displacement of specimen's gage length for simulating more realistic test environment. Each part of separated extensometer are attached to upper and lower part of the specimen's gage length and measures the strain through LVDT sensor, which is individually connected with extensometer. Separated typed extensometer system is a smaller size of existing single typed extensometer system, which have been developed during previous study, and have complemented the disadvantage of usage and structural defects. This device can be applied to variety of material testings in high temperature and high pressure environments, replace the existing extensometer, and is expected to greatly contribute on acquiring more detailed test data.