• 방사성폐기물학회지
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• 제14권1호
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• pp.35-44
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• 2016

Leading national R&D project to design a PWR spent nuclear fuel interim dry storage system that has been under development since mid-2009, which consists of a dual purpose metal cask and concrete storage cask. To ensure the safe operation of dry storage systems in foreign countries, major confinement monitoring techniques currently consist of pressure and temperature measurement. In the case of a dual purpose metal cask, a pressure sensor is installed in the interspace of bolted double lid(primary and secondary lid) in order to measure pressure. A concrete storage cask is a canister based system made of double/redundant welded lid to ensure confinement integrity. For this reason, confinement monitoring method is real time temperature measurement by thermocouple placed in the air flow(air intake and exit) of the concrete structure(over pack and module). The use of various monitoring technologies and operating experiences for the interim dry storage system over the last decades in foreign countries were analyzed. On the basis of the analysis above, development of the confinement monitoring technology that can be used optimally in our system will be available in the near future.

• 방사선산업학회지
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• 제18권2호
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• pp.133-140
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• 2024

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.

• Nuclear Engineering and Technology
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• 제39권2호
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• pp.143-148
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• 2007

Spent nuclear fuel generated at nuclear power plants must be safely stored during interim storage periods. A dry storage cask to safely store the spent nuclear fuel should be able to adequately emit the decay heat from the spent nuclear fuel. Therefore, heat removal tests using a half scale dry storage cask have been performed to estimate the heat transfer characteristics of a dry storage cask under normal, off-normal, and accident conditions. In the normal condition, the heat transfer rate to an ambient atmosphere by convective air through a passive heat removal system reached 83%. Accordingly, the passive heat removal system is designed well and works adequately. In the off-normal condition, the influence of a half blockage in the inlet on the temperature appears minimal. In the accident condition, the temperature rose for 12 hours after the accident, but the temperature rise steadied after 36 hours.

• Journal of Radiation Protection and Research
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• 제21권4호
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• pp.313-327
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• 1996

원전부지내(AR) 사용후핵연료 건식저장방식으로 횡형콘크리트 모듈방식, 금속 저장용기 방식, 콘크리트 저장용기 방식, 수송저장 겸용용기 방식 및 다목적용기 방식 등이 있다. 이중다목적용기 방식을 제외한 다른 방식들은 각각 운영인허가를 받아 이미 세계 각 국에서 사용후핵연료 AR 건식저장에 사용되고 있으며 다목적용기 방식도 최근 개발을 활발히 진행하고 있는 상태이다. AR 건식저장 시설을 운영하고 있거나 추진중인 나라는 미국, 일본, 독일, 캐나다, 스페인, 체코, 스위스 등으로 AR 건식저장을 거쳐 중간저장이나 재처리시설로 수송하는 방식을 채택하고 있다. 우리나라의 경우 월성에서 콘크리트 Silo 건식저장을 이미 사용하고 있으며 일부 다른 원자로도 사용후핵연료 저장능력이 한계에 도달하고 있는 현실을 감안할 때 AR 임시 저장은 불가피한 것으로 여겨진다. 본 보고서에서는 고리를 비롯한 국내원전에 적용 가능한 외국의 AR 저장 시스템 각각에 대하여 설계특성, 설계요건, 기술기준 및 현황 등을 논의하였다. 대부분의 경우 저장용기 인허가 기간은 20년으로 제한하고 있으며 전 수명기간동안 재질의 건전성, 밀봉유지 등이 중요하게 요구되고 있다.

• 방사성폐기물학회지
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• 제21권4호
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• pp.503-516
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• 2023

A transfer cask serves as the container for transporting and handling canisters loaded with spent nuclear fuels from light water reactors. This study focuses on a cylindrical transfer cask, standing at 5,300 mm with an external diameter of 2,170 mm, featuring impact limiters on the top and bottom sides. The base of the cask body has an openable/closable lid for loading canisters with storage modules. The transfer cask houses a canister containing spent nuclear fuels from lightweight reactors, serving as the confinement boundary while the cask itself lacks the confinement structure. The objective of this study was to conduct a structural analysis evaluation of the transfer cask, currently under development in Korea, ensuring its safety. This evaluation encompasses analyses of loads under normal, off-normal, and accident conditions, adhering to NUREG-2215. Structural integrity was assessed by comparing combined results for each load against stress limits. The results confirm that the transfer cask meets stress limits across normal, off-normal, and accident conditions, establishing its structural safety.

• Structural Engineering and Mechanics
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• 제75권2호
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• pp.239-246
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• 2020

In this paper, a novel analytical method, Max-Min Approach (MMA), has been presented and applied to consider the nonlinear vibration of dry cask storage systems. The nonlinear governing equation of the structure has been developed using the shell theory. The MMA results are compared with numerical solutions derived by Runge-Kutta's Method (RKM). The results indicate a satisfying agreement between MMA and numerical solutions. Parametric studies have been conducted on the nonlinear frequency of dry casks. The phase-plan of the problem is also presented and discussed. The proposed approach can potentially ca be extended to highly nonlinear problems.

• 방사성폐기물학회지
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• 제16권2호
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• pp.271-279
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• 2018

국내 경수로형 원전의 사용후핵연료 소내 습식저장 용량의 포화에 대비하기 위해 정부 주도로 2009년부터 2016년까지 7년에 걸쳐 국내 여건에 적합한 수송/저장시스템을 개발하였다. 시스템은 운반과 저장을 겸할 수 있는 금속겸용용기와 저장전용인 콘크리트 저장용기로 효율적인 기술개발을 위해 관련 산학연의 특성과 경험을 적극 활용하여 국내고유 모델을 개발하였고 특허 등록을 추진하여 기술의 독립성도 확보하였다. 현재까지 확보한 다수의 특허 및 기술을 산업계에 개방하여 국내 수요에 대처하고자 2016년과 2017년 두 차례에 걸쳐 기술이전도 추진하였다.

• 방사성폐기물학회지
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• 제22권3호
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• pp.325-338
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• 2024

Interim dry cask storage systems comprising AISI 304 or 316 stainless steel canisters have become critical for the storage of spent nuclear fuel from light water reactors in the Republic of Korea. However, the combination of microstructural sensitization, residual tensile stress, and corrosive environments can induce chloride-induced stress corrosion cracking (CISCC) for stainless steel canisters. Suppressing one or more of these three variables can effectively mitigate CISCC initiation or propagation. Surface-modification technologies, such as surface peening and burnishing, focus on relieving residual tensile stress by introducing compressive stress to near-surface regions of materials. Overlay coating methods such as cold spray can serve as a barrier between the environment and the canister, while also inducing compressive stress similar to surface peening. This approach can both mitigate CISCC initiation and facilitate CISCC repair. Surface-painting methods can also be used to isolate materials from external corrosive environments. However, environmental variables, such as relative humidity, composition of surface deposits, and pH can affect the CISCC behavior. Therefore, in addition to research on surface modification and coating technologies, site-specific environmental investigations of various nuclear power plants are required.

• 방사성폐기물학회지
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• 제16권4호
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• pp.455-472
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• 2018

국내의 사용후핵연료가 증가함에 따라 사용후핵연료 저장조는 곧 포화가 될 것으로 예상된다. 따라서 사용후핵연료 건식저장 운영 및 관리 방안에 대해 연구하는 것은 매우 중요하다. 미국에서는 오랜 기간 건식저장을 운영해왔으며 이를 바탕으로 사용후핵연료 건식저장 운영 및 관리 방안에 대해 많은 연구가 수행되고 있다. 그러나 우리나라에서는 경수로 사용후핵연료건식저장 경험이 없으며 관련 관리방안 및 구체적인 기준이 매우 부족한 현실이다. 건식저장기간 동안 주요한 이슈중의 하나는 건식저장용기 열화현상이며 대표적으로 응력부식균열에 의한 부식현상이 있다. 미국에서는 U.S. DOE, U.S. NRC, 그리고 EPRI 주관 아래 건식저장 캐니스터에서의 염화물 응력부식균열에 관한 많은 연구들을 수행하고 있다. 또한 건식저장 캐니스터의 염화물 응력부식균열 현상을 설명하기 위해 SNL에서는 확률론적 응력부식균열 모델을 제시하였다. 본 논문에서는 SNL에서 제시한 확률론적 응력부식균열 모델을 검토하였으며 모델에 제시된 주요인자들을 세세하게 분석하였다. 본 논문은 우리나라에서 스테인리스 스틸로 제작된 캐니스터를 경수로 사용후핵연료 건식저장으로 이용할 경우, 건식저장 운영 및 관리 방안을 구축하는 대에 좋은 참고문헌이 될 것이라 사료된다.

• 한국전산유체공학회지
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• 제21권2호
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• pp.47-53
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• 2016

This study investigated natural convection flow behavior in airflow path designed in concrete dry storage cask to remove the decay heat from spent nuclear fuels. Using FLUENT 16.1 code, thermal analysis for natural convection was carried out for three dimensional, 1/4 symmetry model under the normal condition that inlet ducts are 100% open. The maximum temperatures on other components except the fuel regions were satisfied with allowable values suggested in nuclear regulation-1536. From velocity and temperature distributions along the flow direction, the flow behavior in horizontal duct of air inlet and outlet duct, annular flow-path and bent pipe was delineated in detail. Theses results will be used as the theoretical background for the composing of airflow path for the designing of passive heat removal system by understanding the flow phenomena in airflow path.