• Journal of Radiation Protection and Research
• /
• 제28권2호
• /
• pp.127-135
• /
• 2003

The primary contributors to the total occupational radiation exposure in operating nuclear power plants are operation and maintenance activities doting refueling outages. The Advanced Power Reactor 1400 (APR1400) includes a number of design improvements and plans to utilize advanced maintenance methods and robotics to minimize the annual collective dose. The major radiation exposure reduction features implemented in APR1400 are a permanent refueling pool seal, quick opening transfer tube blind flange, improved hydrogen peroxide injection at shutdown, improved permanent steam generator work platforms, and more effective temporary shielding. The estimated average annual occupational radiation exposure for APR1400 based on the reference plant experience and an engineering judgment is determined to be in the order of 0.4 man-Sv, which is well within the design goal of 1 man-Sv. The basis of this average annual occupational radiation exposure estimation is an eighteen (18) month fuel cycle with maintenance performed to steam generators and reactor coolant pumps during refueling outage. The outage duration is assumed to be 28 days. The outage work is to be performed on a 24 hour per day basis, seven (7) days a week with overlapping twelve (12) hour work shifts. The occupational radiation exposure for APR1400 is also determined by an alternate method which consists of estimating radiation exposures expected for the major activities during the refueling outage. The major outage activities that cause the majority of the total radiation exposure during refueling outage such as fuel handling, reactor coolant pump maintenance, steam generator inspection and maintenance, reactor vessel head area maintenance, decontamination, and ICI & instrumentation maintenance activities are evaluated at a task level. The calculated value using this method is in close agreement with the value of 0.4 man-Sv, that has been determined based on the experience aid engineering judgement. Therefore, with the As Low As Reasonably Achievable (ALARA) advanced design features incorporated in the design, APR1400 design is to meet its design goal with sufficient margin, that is, more than a factor of two (2), if operated on art eighteen (18) month fuel cycle.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2004년도 ICCAS
• /
• pp.1520-1524
• /
• 2004

This paper describes the development of a robotic maintenance system for use in a maintenance operation of the nozzle dam in a water chamber of a steam generator at the Kori nuclear power plant in Korea. The robotic maintenance system was designed to minimize the personnel exposure to a hazardous radioactive environment. This robotic maintenance system is operated by a teleoperated control which was designed to perform the nozzle dam maintenance tasks in a remote manner without endangering the human workers. Specific maintenance tasks involve the transportation, insertion, and removal of nozzle dams in a water chamber inside a steam generator via a narrow man-way entrance port. The developed robotic maintenance system has two major subsystems: a two degrees of freedom guiding device acting as the main guiding arm and a master-slave manipulator with a kinematic dissimilarity. The mechanical design considerations, control system, and capabilities of the robotic maintenance system are presented. Finally, a graphical representation of the nozzle dam maintenance processes in a simulated work environment are also demonstrated.

• Journal of Radiation Protection and Research
• /
• 제34권4호
• /
• pp.176-183
• /
• 2009

원전 계획예방정비기간 증기발생기 수실작업 등은 매우 높은 방사선량율을 보이는 지역으로, 짧은 시간 동안 작업으로 종사자는 높은 피폭을 받을 가능성이 있다. 특히, 방사성물질과 접촉작업을 하는 손 부위에서 고피폭이 예상된다. 이런 점을 고려하여 2004년 수행된 국내 원전의 복수선량계 알고리즘 적용성 시험의 TLD 판독결과를 이용하여 고피폭 접촉 작업의 방사선장을 분석하였다. 그 결과, 원전 고피폭 접촉작업의 입사방사선장은 고에너지 광자(High Energy Photon Field)에 의한 피폭으로 해석되었다. 한편 2009년 울진 4호기 계획예방정비기간 S/G 정비작업과 월성 1호기 압력관 교체작업에 참여한 방사선작업종사자에 대해 말단선량 현황과 방사선장을 분석하기위한 현장시험을 실시하였다. 그 결과 입사방사선장은 고에너지 방사선장으로 확인되었다.

• 대한인간공학회지
• /
• 제36권5호
• /
• pp.559-568
• /
• 2017

Objective: The aim of this study is to investigate the effective managerial factors influencing dose reduction of the nozzle dam installation and removal tasks ranking within top 3 in viewpoint of average collective dose of nuclear power plant maintenance job. Background: International Commission on Radiation Protection (ICRP) recommended to reduce unnecessary dose and to minimize the necessary dose on the participants of maintenance job in radiation fields. Method: Seven sessions of nozzle dam installation and removal task logs yielded a multiple regression model with collective dose as a dependent variable and work time, number of participants, space doses before and after shield as independent variables. From the sessions in which a significant reduction in collective dose occurred, the effective managerial factors were elicited. Results: Work time was the most important factor contributing to collective dose reduction of nozzle dam installation and removal task. Introduction of new technology in nozzle dam design or maintenance job is the most important factor for work time reduction. Conclusion: With extended task logs and big data processing technique, the more accurate prediction model illustrating the relationship between collective dose reduction and effective managerial factors would be developed. Application: The effective managerial factors will be useful to reduce collective dose of decommissioning tasks as well as regular preventive maintenance tasks for a nuclear power plant.

• Journal of Radiation Protection and Research
• /
• 제35권2호
• /
• pp.57-62
• /
• 2010

원전 계획예방정비기간 증기발생기 수실작업, 가압기 전열관교체 또는 압력관피더 제거작업 지역 등은 높은 방사선량률을 보이는 지역으로, 짧은 시간 동안의 작업으로 작업종사자는 높은 피폭을 받을 가능성이 있다. 특히, 방사성물질과 접촉하는 손 부위는 높은 피폭이 일어날 수 있다. 이런 점을 고려하여 국내 가압경수로원전과 가압중수로원전의 계획 예방정비기간 중 증기발생기 수실 노즐댐 설치와 제거작업, 원자로 냉각재펌프 보수작업, 원자로헤드 보수 및 검사작업 등과 같은 고피폭 접촉작업에서 방사선작업종사자의 말단선량을 측정하기위한 현장시험을 실시하였다. 여기에 참여한 작업종사자는 가슴과 등 부위에 일상적인 절차에 따른 복수선량계를 패용한 것 이외에 손목에 개인선량계를 추가로 패용하였고, 손가락 부위에는 말단선량계 (Extremity dosimeter)를 패용하였다. 그 결과, 손가락이 받는 등가선량은 각각 손목이 받는 등가선량 및 가슴 또는 등 부위가 받는 등가선량과 일정한 비율로 평가됨을 확인하였다.

• 방사선산업학회지
• /
• 제11권3호
• /
• pp.123-130
• /
• 2017

Concerns about high radiation exposure to the hands of radiation workers who may contact with radioactive contamination on surfaces in a nuclear power plant (NPP) had been raised, and the Korean regulatory body required the extremity dose estimation during contact tasks with radioactive materials. Korean NPPs conducted field tests to identify the incident radiation to the hands of radiation workers who may contact with radioactive contamination during maintenance periods. The results showed that the radiation fields for contact tasks are dominated by high energy photons. It was also found that the radiation doses to the hands of radiation workers in Korean NPPs were much less than the annual dose limits for extremities. This approach can be applicable to measure and estimate the extremity dose to the hands of medical workers who handle the radioactive materials in a hospital.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 1996년도 춘계학술대회 논문집
• /
• pp.200-204
• /
• 1996

It is a great number of problem for the man to perform maintenance and repairing work owing to radioactive effusion for a nuclear fuel and the pollution of an related equipment in nuclear power plants. Therefore, the vision processing system presented in this research requires to maintain the good performance under the radioactive circumstances and to safety the real time processing system presented in this research requires to maintain the good performance under the radioactive circumstances and to safety the real time processing. The proposed vision scheme adapts the gradient and Laplacian operator to perform the high speed processing in an edge detection and the centroid formula at each direction to obtain the center position of a holes using DSPs