• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2412-2420
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• 2024

The International Atomic Energy Agency (IAEA) mandates safeguards to ensure non-proliferation of nuclear materials. Among inspection techniques used to detect partial defects within spent nuclear fuel (SNF), gamma emission tomography (GET) has been reported to be reliable for detection of partial defects on a pin-by-pin level. Conventional GET, however, is limited by low detection efficiency due to the high density of nuclear fuel rods and self-absorption. This paper proposes a new type of GET named Spent Fuel Internal Tomography (SFIT), which can acquire sinograms at the guide tube. The proposed device consists of the housing, shielding, C-shaped collimator, reflector, and gadolinium aluminum gallium garnet (GAGG) scintillator. For accurate attenuation correction, the source-distinguishable range of the SFIT device was determined using MC simulation to the region away from the proposed device to the second layer. For enhanced inspection accuracy, a proposed specific source-discrimination algorithm was applied. With this, the SFIT device successfully distinguished all source locations. The comparison of images of the existing and proposed inspection methods showed that the proposed method, having successfully distinguished all sources, afforded a 150 % inspection accuracy improvement.

• Journal of Welding and Joining
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• 제19권1호
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• pp.88-94
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• 2001

DUPIC (Direct use of spent PWR fuel in CANDU reactors) nuclear fuel is a CANDU fuel fabricated remotely from spent PWR fuel materials in a hot cell. The soundness of the end closure welds of nuclear fuel elements is an important factor for the safety and performance of nuclear fuel. To evaluate the soundness of the end closure welds of DUPIC fuel element, a precise X-ray inspection system is developed using a micro-focus X-ray generator with an image intensifier and a real time camera system. The fuel elements made of Zircaloy-4 and stainless steel by an Nd:YAG laser welding and a TIG welding aye inspected by the developed inspection system. The soundness of the welds of the fuel elements was confirmed by the X-ray inspection process, and the irradiation test of DUPIC fuel elements has been successfully completed at the HANARO research reactor.

• 한국구조물진단유지관리공학회 논문집
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• 제9권2호
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• pp.95-102
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• 2005

방사성폐기물을 저장하는 시설은 부지선정에 상당한 어려움과 많은 시간이 소요되고 있으며, 이러한 문제로 인하여 발전소내의 부지에 방사성폐기물의 수용용량을 증가시키는 방법이 단기적인 해결방안으로 고려되고 있다. 캐나다에서 개발한 사용후 핵연료 건식저장시스템을 국내에 도입하려는 노력이 진행중이다. 본 연구에서는 유한요소해석을 통하여 사용후 핵연료 건식저장시스템의 비정상운영 조건인 사용후 핵연료 이송차량의 충돌사고와 핵연료를 운반하는 플라스크 낙하사고에 대한 구조적 안전성을 검토하였다.

• Nuclear Engineering and Technology
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• 제46권6호
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• pp.875-882
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• 2014

In terms of safety and the efficient management of spent fuel storage, detecting failed fuel is one of the most important tasks in a CANada Deuterium Uranium (CANDU) reactor operation. It has been successfully demonstrated that in a CANDU reactor, on-power failed fuel detection and location systems, along with alarm area gamma monitors, can detect and locate defective and suspect fuel bundles before discharging them from the reactor to the spent fuel storage bay. In the reception bay, however, only visual inspection has been used to identify suspect bundles. Gaseous fission product and delayed neutron monitoring systems cannot precisely distinguish failed fuel elements from each fuel bundle. This study reports the use of a sipping system in a CANDU reactor for the integrity assessment of spent fuel bundles. The integrity assessment of spent fuel bundles using this sipping system has shown promise as a nondestructive test for detecting a defective fuel bundle in a CANDU reactor.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4695-4702
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• 2023

Nuclear power plants play a pivotal role in the global energy infrastructure, fulfilling a substantial share of the world's energy requirements in a sustainable way. The management of these facilities, especially the handling of spent nuclear fuel (SNF), necessitates meticulous inspections to guarantee operational safety and efficiency. However, the prevailing inspection methodologies lean heavily on human operators, which presents challenges due to the potential hazards of the SNF environment. This study introduces the design of a novel Pre-Batched Inspection Strategy (PBIS) that integrates robotic automation and image processing techniques to bolster the inspection process. This methodology deploys robotics to undertake tasks that could be perilous or time-intensive for humans, while image processing techniques are used for precise identification of SNF targets and regulating the robotic system. The implementation of PBIS holds considerable promise in minimizing inspection time and enhancing worker safety. This paper elaborates on the structure, capabilities, and application of PBIS, underlining its potential implications for the future of nuclear energy inspections.

• 한국압력기기공학회 논문집
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• 제16권2호
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• pp.18-24
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• 2020

When a damage occurs in the nuclear fuel burning in the reactor, fission products that should be in the nuclear fuel rod are released into the reactor coolant. In this case, sipping test, a series of non-destructive inspection methods, are used to find leakage in nuclear fuel assemblies during the power plant overhaul period. In addition, the sipping test is also used to check the integrity of the spent fuel for moving to an intermediate dry storage, which is carried out as the first step of nuclear decommissioning, . In this paper, the principle and characteristics of the sipping test are described. The structure of the sipping inspection equipment is largely divided into a suction device that collects fissile material emitted from a damaged assembly and an analysis device that analyzes their nuclides. In order to make good use of the sipping technology, the radioactive level behavior of the primary system coolant and major damage mechanisms in the event of nuclear fuel damage are also introduced. This will be a reference for selecting an appropriate sipping method when dismantling a nuclear power plant in the future.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.890-898
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• 2018

Nondestructive inspection (NDI) is an integral part of structural integrity analyses of dry storage casks that house spent nuclear fuel. One significant concern for the structural integrity is stress corrosion cracking in the heat-affected zone of welds in the stainless steel canister that confines the spent fuel. In situ NDI methodology for detection of stress corrosion cracking is investigated, where the inspection uses a delivery robot because of the presence of the harsh environment and geometric constrains inside the cask protecting the canister. Shear horizontal (SH) guided waves that are sensitive to cracks oriented either perpendicular or parallel to the wave vector are used to locate welds and to detect cracks. SH waves are excited and received by electromagnetic acoustic transducers (EMATs) using noncontact ultrasonic transduction and pulse-echo mode. A laboratory-scale canister mock-up is fabricated and inspected using the proposed methodology to evaluate the ability of EMATs to excite and receive SH waves and to locate welds. The EMAT's capability to detect notches from various distances is evaluated on a plate containing 25%-through-thickness surface-breaking notches. Based on the results of the distances at which notch reflections are detectable, NDI coverage for spent nuclear fuel storage canisters is determined.

• Journal of Radiation Protection and Research
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• 제49권1호
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• pp.29-39
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• 2024

Background: The gamma emission tomography (GET) device has been reported a reliable technique to inspect partial defects within spent nuclear fuel (SNF) of pin-by-pin level. However, the existing GET devices have low accuracy owing to the high attenuation and scatter probability for SNF inspection condition. The purpose of this study is to design and optimize a Yonsei single-photon emission computed tomography version 2 (YSECT.v.2) for fast inspection of SNF in water storage by acquisition of high-quality tomographic images. Materials and Methods: Using Geant4 (Geant4 Collaboration) and DETECT-2000 (Glenn F. Knoll et al.) Monte Carlo simulation, the geometrical structure of the proposed device was determined and its performance was evaluated for the ¹³⁷Cs source in water. In a Geant4-based assessment, proposed device was compared with the International Atomic Energy Agency (IAEA)-authenticated device for the quality of tomographic images obtained for 12 fuel sources in a 14 × 14 Westinghouse-type fuel assembly. Results and Discussion: According to the results, the length, slit width, and septal width of the collimator were determined to be 65, 2.1, and 1.5 mm, respectively, and the material and length of the trapezoidal-shaped scintillator were determined to be gadolinium aluminum gallium garnet and 45 mm, respectively. Based on the results of performance comparison between the YSECT.v.2 and IAEA's device, the proposed device showed 200 times higher performance in gamma-detection sensitivity and similar source discrimination probability. Conclusion: In this study, we optimally designed the GET device for improving the SNF inspection accuracy and evaluated its performance. Our results show that the YSECT.v.2 device could be employed for SNF inspection.

• 방사성폐기물학회지
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• 제11권1호
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• pp.31-39
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• 2013

핵연료는 원자로 운전 중 예기치 못한 상황에서 연료 결함을 초래할 수 있다. 핵연료 결함은 연료봉의 수소화나 이물질에 의한 금속 마모, 그리고 펠렛과 피복관의 상호작용에 의해 피복관이 손상된다. 이렇게 손상된 핵연료의 결함원인을 규명하는 것은 원자력발전의 안전운전에 중요하다고 사료된다. 핵연료가 손상되면 원자로 냉각재가 오염되어 원자로 출력을 낮추거나, 발전소를 정지할 수도 있다. 모든 사용후연료는 건식저장고로 이동 보관되어야 하나, 결함연료는 이동할 수 없으므로 이 연구의 목적은 중수로형 원자로에서 연료가 인출된 후 사용후연료 저장조에서 보관된 연료에 대하여 결함 여부를 판단할 수 있는 기술을 개발하고자 하였다. 이 연구를 통하여 핵종 누설 검출 기술을 이용한 사용후연료 검사기술을 개발하였으며, 이 기술을 월성발전소에 적용함으로써, 검사기술 및 검사시스템에 대한 성능을 입증하였다.

• 방사성폐기물학회지
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• 제13권2호
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• pp.163-169
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• 2015

국내 원자력발전소에서는 사용후핵연료 저장용량의 확대를 위해 사용후핵연료저장조에 조밀저장대를 설치하고 있지만 한빛원전은 2024년에 포화가 예상된다. 또한 10개의 원자력발전소가 2029년까지 설계수명에 도달하게 된다. 하지만 원전운영과 해체를 위한 국내 사용후핵연료 관리정책은 아직 결정되지 않은 상황이다. 미국의 경우 원전해체시 사용후핵연료를 중간 저장시설 또는 영구처분장으로 이송하기 전까지 임시적으로 독립된 사용후연료저장조(이하 'SFPI') 방식을 운영하는 사례가 있다. SFPI는 원전해체시 운전정지 후 사용후핵연료를 저장하는데 있어서 방사선 노출 저감, 운영비용 절감, 안전성 보강 등의 효과를 기대할 수 있다. 따라서 이 논문에서는 미국의 SFPI 운영경험, 시스템, 적용규정 등에 대한 사례연구를 수행하였다. 결론적으로 SFPI 국내 적용을 위해서는 사용후핵연료저장 계통의 설계변경 범위 및 예상 소요비용 확정, 원전 해체계획에 설비개선 계획 반영제출, 주기적안전성평가(PSR) 방법 등을 활용한 안전성 평가(운영기간 10 년), 설계변경을 위한 운영 변경허가 신청, 규제기관 심사 및 허가 취득, 설계변경 수행, 규제기관의 확인점검, SFPI 운영을 위한 교육 및 시운전, SFPI 운영 및 정기검사, SFPI 해체 등의 절차가 필요하다.