• Journal of Radiation Protection and Research
• /
• 제36권4호
• /
• pp.174-182
• /
• 2011

With the reactor operation conditions - 4.3 wt% $^{235}U$ initial enrichment, burn-up 55,000 MWd/MTU, average power 34 MW/MTU for three periods burned time for 539.2 days per period and cooling time for 100 hours after shut down, to set up the condition to determine the minimum height (depth) of spent fuel storage pool to shut off the radiation out of the spent fuel storage pool and to store spent fuels safely, the dose rate on the specific position directed to the surface of spent fuel storage pool induced by the neutron and gamma-ray from spent fuels are evaluated. The length of spent fuel is 381 cm, and as the result of evaluation on each position from the top of spent fuel to the surface of spent fuel storage pool, it is difficult for neutrons from spent fuels to pass through the water layer of maximum 219 cm (600 cm from the floor of spent fuel storage pool) and 419 cm (800 cm from the floor of spent fuel storage pool) for gamma-ray. Therefore, neutron and gamma-ray from spent fuels can pass through below 419 cm (800 cm from the floor) water layer directed to the surface of spent fuel storage pool.

• Nuclear Engineering and Technology
• /
• 제45권3호
• /
• pp.377-384
• /
• 2013

During the last three decades, South Korean nuclear power plants have discharged about 5,950 tons of spent fuel and the maximum burn-up reached 55 GWd/MTU in 2002. This study was performed to support the development of Korean dry spent fuel storage alternatives. First, we chose V5H-$17{\times}17$ and KSFA-$16{\times}16$ as representative domestic spent fuels, considering current accumulation and the future generation of the spent fuels. Examination reveals that their average burn-ups have already increased from 33 to 51 GWd/MTU and from 34.8 to 48.5 GWd/MTU, respectively. Evaluation of the fuel characteristics shows that at the average burn-up of 42 GWd/MTU, the oxide thickness, hydrogen content, and hoop stress ranged from $30{\sim}60{\mu}m$, 250 ~ 500 ppm, and 50 ~ 75 MPa, respectively. But when burn-up exceeds 55 GWd/MTU, those characteristics can increase up to 100 ${\mu}m$, 800 ppm, and 120 MPa, respectively, depending on the power history. These results demonstrate that most Korean spent nuclear fuels are expected to remain within safe bounds during long-term dry storage, however, the excessive hoop stress and hydrogen concentration may trigger the degradation of the spent fuel integrity early during the long-term dry storage in the case of high burn-up spent fuels exceeding 45 GWd/MTU.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2008년도 춘계학술대회 논문집
• /
• pp.488-490
• /
• 2008

This study aims to design the high-capacity vol-oxidizer using simulated fuels instead of spent nuclear fuels. Simulated fuels are fabricated by blending tungsten powder with silicon carbide powder, and thereafter, paraffin coating covers simulated fuels to increase their strength. An oxidation experiment using simulated fuels have been carried out in order to analyze oxidation characteristics similar to spent fuels. After oxidation, simulated fuels were almost oxidized to be powders. Increased volume of simulated fuels approached to spent fuels. These results can be utilized as important informations for designing a high-capacity vol-oxidizer.

• Nuclear Engineering and Technology
• /
• 제31권6호
• /
• pp.23-38
• /
• 1999

This study addresses the reference spent fuel and its characteristics for developing a geological repository concept. As a disposal capacity of the reference repository system to be developed, spent fuel inventories were projected based on the basis of the Nuclear Energy Plan of the Long-term National Power Program. The reference spent fuel encompassing a variability in characteristics of all existing and future spent fuels of interest was defined. Key parameters in the reference fuel screening processes were the nuclear and mechanical design parameters and the burnup histories for existing spent fuels as of 1996 and for future spent fuels with the more extended burnup the initial enrichment and its expected turnup. The selected reference fuel was characterized in terms of initial enrichment, bumup, dimension, gross weight and age. Also the isotopic composition and the radiological properties are quantitatively identified. This information provided in this study could be used as input for repository system development and performance assessment and applied in fuel material balance evaluation for the various types of back-end fuel cycle studies.

• Journal of Radiation Protection and Research
• /
• 제34권1호
• /
• pp.1-7
• /
• 2009

It is expected that a substantial amount of spent fuels will be transported from the four nuclear power plant (NPP) sites in Korea to a hypothetical centralized interim storage facility or a final repository in the near future. The cost for the transportation is proportional to the amount of spent fuels. In this paper, a cost estimation program is developed based on the conceptual design of a transportation system and a logistics analysis. Using the developed computer program, named as CASK, the minimum capacity of a centralized interim storage facility (CISF) and the transportation cost for PWR spent fuels are calculated. The PWR spent fuels are transported from 4 NPP sites to a final repository (FR) via the CISF. Since NPP sites and the CISF are located along the coast, a sea-transportation is considered and a road-transportation is considered between the CISF and the FR. The result shows that the minimum capacity of the interim storage facility is 15,000 MTU.

• 방사성폐기물학회지
• /
• 제19권1호
• /
• pp.61-74
• /
• 2021

A paradigm shift in the government's energy policy was reflected in its declaration of early closure of old nuclear plants as well as cancellation of plans for the construction of new plants. To this end, unit 1 of Kori Nuclear Power Plant was permanently shut down and is set for decommission. Based on these changes, the off-site transport of spent fuels from nuclear power plants has become a critical issue. The purpose of this study is to develop an optimized method for transportation of spent fuels from Kori Nuclear Power Plant's units 1, 2, 3, and 4 to an assumed interim storage facility by simulating the scenarios using the Flexsim software, which is widely used in logistics and manufacturing applications. The results of the simulation suggest that the optimized transport methods may contribute to the development of delivery schedule of spent fuels in the near future. Furthermore, these methods can be applied to decommissioning plan of nuclear power plants.

• 방사성폐기물학회지
• /
• 제13권3호
• /
• pp.201-209
• /
• 2015

우리나라에서는 현재 23기의 원자력발전소를 운영 중에 있으며, 이들 원자력발전소로부터 발생하는 사용후핵연료를 처분대상으로 기준 심지층 처분시스템을 개발한 바 있다. 현재 이 기준 심지층 처분시스템은 초기농축도 4.5wt%, 방출연소도 55 GWd/MtU의 40 년 냉각된 사용후핵연료를 기준으로 하고 있다. 본 논문에서는 처분효율 및 경제성 향상 방안의 일환으로서 사용후핵연료의 종류 및 연소도 특성 등 발생특성을 검토하였다. 그리고 기준 사용후핵연료에 비하여 길이가 짧고 연소도가 비교적 낮은 사용후핵연료에 대한 처분용기 개념을 도출하고 열해석을 수행하여 처분시스템 개념을 제시하였다. 또한, 이 처분시스템 개념과 기준 사용후핵연료 처분시스템 개념을 처분밀도, 처분면적 등의 처분효율 및 구리와 벤토나이트 소요량 등 경제성 관점에서 비교 분석한 결과 약 20% 이상 향상을 보이는 것을 확인하였다. 본 분석결과는 사용후핵연료 관리정책 수립 및 실제 처분시스템 설계에 활용될 수 있을 것으로 사료된다.

• 융복합기술연구소 논문집
• /
• 제2권1호
• /
• pp.7-12
• /
• 2012

Spent fuels are discharged from nuclear reactors as a result of power generations. The spent fuels would be considered as a useful resources because the main constituent is uranium and some other actinides are included in them. In order to utilize the resources chemical processes should be developed to treat the spent fuels and obtain uranium and other actinides to be fueled in a fast reactor. The technologies are categorized into wet and dry processes. In this study, the current status of such technologies is summarized to give a insight and a deep understanding on nuclear fuel cycles.

• 방사성폐기물학회지
• /
• 제6권2호
• /
• pp.147-154
• /
• 2008

국내 원자력발전소의 사용후핵연료 저장용량의 포화가 10년 이내에 예상되고 있으며, 소외중간저장방식을 관리 방안으로서 선정할 경우, 상당한 양의 사용후핵연료 운반이 해상 혹은 육로를 통해 매년 이루어져야만 한다. 본 논문에서는 4곳의 원자력발전소부지에 분산 저장되어 있는 사용후핵연료를 해안에 위치한 가상의 중간저장시설과 영구처분시설을 대상으로 사용후핵연료 운반물량을 효과적으로 분석할 수 있는 체계를 구축하였다. 각 발전소 부지, 중간저장시설, 영구처분시설의 저장고를 중심으로 사용후핵연료 물질 수지식을 세우고, 이에 대한 해를 VISUAL BASIC으로 구하여 운반 물량 분석이 용이하게 수행할 수 있는 컴퓨터 프로그램(CASK)을 개발하였다. 개발된 물량 분석 프로그램을 활용하여 4개 원자력 발전소 부지로부터 사용후핵연료 운반 물량을 분석하고, 운반물량 파라미터 분석을 통하여 본 프로그램의 활용도를 보였다. 개발된 사용후핵연료 운반 물량 분석 체계는 향후 운반비용 분석에도 유용하게 활용될 것이다.

• Nuclear Engineering and Technology
• /
• 제55권8호
• /
• pp.3102-3113
• /
• 2023

Following the Fukushima nuclear disaster, the simulation of accidents in the spent fuel pool has become more noticeable. Despite the low amount of decay heat power, the consequences of the accidents in a spent fuel pool (SFP) can be severe due to the high content of long-lived radionuclides and lack of protection by the pressure vessel. In this study, the loss-of-cooling accident (LOFA) for the VVER-1000/V446 spent fuel pool is simulated by employing RELAP5 and MELCOR 1.8.6 as the best estimate and severe accident analysis codes, respectively. For two cases with different total power levels, decay heat of spent fuels is calculated by ORIGEN-II code. For modeling SFP of a VVER-1000, a qualified nodalizations are considered in both codes. During LOFA in SFP, the key sequences such as heating up of the pool water, boiling and reducing the water level, uncovering the spent fuels, increasing the temperature of the spent fuels, starting oxidation process (generating Hydrogen and extra power), the onset of fuel melting, and finally releasing radionuclides are studied for both cases. The obtained results show a reasonable consistency between the RELAP5 and MELCOR codes, especially before starting the oxidation process.