중수로 증기발생기 다중 전열관 파단사고시 파단 전열관 수에 대한 영향 분석

유선오,이경원 한국압력기기공학회 2022 한국압력기기공학회 논문집 Vol.18 No.2

An influence analysis on multiple steam generator tube rupture (mSGTR) followed by an unmitigated station blackout is performed to compare the plant responses according to the number of ruptured u-tubes under the assumption of a total of 10 ruptured u-tubes. In all calculation cases, the transient behaviour of major thermal-hydraulic parameters, such as the discharge flow rate through the ruptured u-tubes, reactor header pressure, and void fraction in the fuel channels is found to be overall similar to that of the base case having a single SG with 10 u-tubes ruptured. Additionally, as the conditions of low-flow coolant with high void fraction in the broken loop continued, causing the degradation of decay heat removal, the peak cladding temperature (PCT) would be expected to exceed the limit criteria for ensuring nuclear fuel integrity. However, despite the same total number of ruptured u-tubes, because of the different connection configuration between the SG and pressurizer, a difference is foud in time between the pressurizer low-level signal and reactor header low-pressure signal, affecting the time to trip the reactor and to reach the PCT limit. The present study is expected to provide the technical basis for the accident management strategy for mSGTR transient conditions of CANDU-6 plants.

중수로 원전 교류전원 완전상실 사고 시 일차측 열수송 펌프 밀봉 누설 영향에 대한 코드 분석

유선오,조민기,이경원,백경록 한국압력기기공학회 2020 한국압력기기공학회 논문집 Vol.16 No.1

This study aims to develop and advance the evaluation technology for assessing PHWR safety. For this purpose, the complete loss of AC power or station blackout (SBO) was selected as a target accident scenario and the analysis model to evaluate the plant responses was envisioned into the MARS-KS input model. The model includes the main features of the primary heat transport system with a simplified model for the horizontal fuel channels, the secondary heat transport system including the shell side of steam generators, feedwater and main steam line, and moderator system. A steady state condition was achieved successfully by running the present model to check out the stable convergence of the key parameters. Subsequently, through the SBO transient analyses two cases with and without the coolant leakage via the PHTS pumps were simulated and the behaviors of the major parameters were compared. The sensitivity analysis on the amount of the coolant leakage by varying its flow area was also performed to investigate the effect on the system responses. It is expected that the results of the present study will contribute to upgrading the evaluation technology of the detailed thermal hydraulic analysis on the SBO transient of the operating PHWRs.

Numerical Calculation of the Unsteady Flow Field in a Tank during Drainage

유선오,조종철 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-

UNIST-DISNY 설비 피복관에 침적된 크러드의 열전달 모델링

유선오,김지용,방인철 한국압력기기공학회 2023 한국압력기기공학회 논문집 Vol.19 No.2

This study presents a CRUD modelling to simulate the thermal resistance behavior of CRUD, deposited on the surface of a cladding tube of a fuel assembly. When heat produced from fuels transfers to a coolant through a cladding tube, the CRUD acting as an additional thermal resistance is expressed as two layers, i.e., a solid oxide layer and an imaginary fluid layer, which are added to the experimental tube’s heat structure of the MARS-KS input data. The validation calculation for the experiments performed in UNIST-DISNY facility showed that the center and surface temperatures of the cladding tube increased as the porosity and the steam amount inside pores of the CRUD got higher. In addition, the temperature gradient in the imaginary fluid layer was calculated to be larger than that in the solid oxide part, indicating that the steam amount inside the layer acted more largely as thermal resistance. It was also evaluated through sensitivity calculations that the cladding tube temperature was more sensitive to the CRUD porosity and the steam amount in pores than to the inlet flow rate of the coolant.

족부 연부조직에 발생한 골연골종 - 1예 보고 -

유선오,심창구,김철호,조명일,문진응,Yu, Sun-O,Shim, Chang-Goo,Kim, Churl-Ho,Joe, Myoung-Il,Moon, Jin-Woong 대한족부족관절학회 2001 대한족부족관절학회지 Vol.5 No.1

We experienced a case of soft tissue osteochondroma in the foot. The 43-years-old male was complained palpable mass and mild pain at the heel for 3 years. The plain radiograpy revealed a bony mass without connection of neighbor bone in the heel. The osteochondroma in the soft tissue is rare benign tumor. The mass was removed en bloc. The gross and histologic findings were consistent with osteochondroma. The differential diagnosis includes myositis ossificans, tumoral calcinosis, synovial chondromatosis, soft tissue osteochondroma, and true osteochondroma which arises from bone. The symptom was improved. After postoperative 1 year, recurrence was not.

광범위 외측 도달법을 이용한 종골 골절의 경피적 및 최소 내고정술

유선오,김주성,김종진,Yu, Sun-O,Kim, Joo-Sung,Kim, Jong-Jin 대한족부족관절학회 2002 대한족부족관절학회지 Vol.6 No.2

Purpose: To present the clinical analysis of the results obtained in 38 cases of displaced intraarticular calcaneal fractures undergone combined percutaneous axial pin fixation of calcaneal body and minimal internal fixation using extensile lateral approach. Materials and Methods: From March 2000 to February 2002, thirty-eight displaced intraarticular fractures of the calcaneus in 35 patients were fixed with 3.5mm cannulated screws and percutaneous 2.5mm K-wires. The extensile lateral approach was used in all cases. The average follow-up period was 16 months. Clinical evaluation was assessed according to the Ankle-Hind Foot Scale of American Orthopedic Foot and Ankle Society. Results: The clinical results were graded as excellent in 8 cases(21%), good in 22 cases(58%), fair in 6 cases(16%), and poor in 2 cases(5%). Two cases of poor result were type IV of Sanders classification. The postoperative reduction status of the articular surface was analyzed by computed tomography in all cases and was found to be less 2mm of step off in 30 cases and between 2 and 4mm in 8 cases. Unsatisfactory results were correlated with severity of articular comminution and failure to obtain accurate reduction of the articular surface. Using early functional postoperative care, all fractures healed without secondary displacement except 1 case on an average of ten weeks. Two cases had superficial necrosis of the wound margins, however, secondary wound healing was uneventful and skin grafting was not needed. Conclusion: Combined minimal internal fixation and percutaneous pin fixation using extensile lateral approach is useful operative method of intraarticular calcaneal fractures because providing enough stability to permit functional aftercare and allowing excellent anatomical reduction. In addition, this method diminishes the risk of lateral soft tissue problems.

거골의 전내측에 큰 골극이 동반된 족관절의 내측 충돌증후군

유선오,김종진,Yu, Sun-O,Kim, Jong-Jin 대한족부족관절학회 2002 대한족부족관절학회지 Vol.6 No.1

After a severe ankle sprain, the incidence of residual complaints, particularly on the medial side of the joint, is high. We experienced a case of medial impingement between medial malleolus and anteromedial osteophyte of talus, specially in the dorsiflexion of the right ankle. Twenty five-year-old male was complained tenderness and chronic pain over the medial side of the right anklel for 3 years after an inversion sprain of the ankle. The plain radiography revealed a bony osteophyte on the anteromedial side of talus. The patient was treated by the open arthrotomy of the ankle. At surgery, impingement between articular surface of medial malleolus and osteophyte of the talus was observed when ankle dorsiflexion was done. Chondral lesion of medial malleolus and chondromalacic degeneration on anteromedial talus was viewed. Surgical removal of osteophyte on talus and debridement and multiple drilling of chondral lesion on medial malleolus was done. The symptom was improved. After postoperative 1 year, recurrence was not.

초기 진단에 어려움이 있는 불안정성 족근 중족 관절 미세 손상에 대한 도수 정복 및 내고정술 후 임상적 결과

유선오,박용욱,김주성,이기준,Yu, Sun-O,Park, Yong-Wook,Kim, Joo-Sung,Lee, Gi-Jun 대한족부족관절학회 2004 대한족부족관절학회지 Vol.8 No.1

Purpose: The purpose of this study was to evaluate retrospectively the clinical results of closed reduction and percutaneous screw fixation for unstable injuries on stress radiographs in subtle injuries of Lisfranc joint. Materials and Methods: From June 1997 to March 2003, 6 cases of unstable injuries on stress radiograph in subtle injuries of Lisfranc joint were treated by percutaneous cannulated screw fixation after closed reduction. All cases were injuried by indirect force (twisting injury). The average diastasis between the 1st and 2nd metatarsal base was 3 mm (2-4 mm) on initial nonweight bearing AP radiograph. The average follow-up period was 20 months. Clinical evaluation was assessed according to the American Orthopedic Foot and Ankle Society (AOFAS) midfoot score. Results: The AOFAS midfoot score was average 86 (80-90) points. The average diastasis between 1st and 2nd metatarsal base was 2 mm (1-3 mm) on weight bearing AP radiograph in final follow up. The final diastasis was increased slightly than diastasis in initial postoperative radiographs. But the clinical results were good. There was no correlation between the degree of diastasis and the clinical results. On weight bearing lateral radiograph, the average difference with normal foot in the distance between plantar aspect of 5th metatarsus and medial cuneiform was 2 mm (0-3 mm). One case had mild arthritic change on the radiographs. Conclusion: When the Lisfranc injuries, especially in the subtle injuries were suspicious, the stress views are helpful to assess stability of the Lisfranc injuries and planning of treatment. For unstable injuries on stress radiographs in subtle injuries of Lisfranc joint, closed reduction and percutaneous screw fixation is useful method to expect good clinical results.

CORQUENCH 코드를 활용한 중수로 calandria vault에서의 MCCI 거동 분석

유선오 한국압력기기공학회 2021 한국압력기기공학회 논문집 Vol.17 No.2

Molten corium-concrete interaction (MCCI) is one of the most important phenomena that can lead to the potential hazard of late containment failure due to basemat penetration during a severe accident. In this study, MCCI analytical models of the CORQUENCH code were prepared through verification calculations of several experiments, which had been performed using concrete types similar to those of the calandria vault floor in CANDU-6 plants. The behaviors of thermal-hydraulic variables related to MCCI phenomena were analyzed under the conditions of dry floor and water flooding during the severe accident stemming from a hypothetic station blackout. Uncertainty analyses on the ablation depth were also carried out. It was estimated that the concrete ablation was not interrupted due to the continuous MCCI process under the dry condition but was terminated within 24 hours under the water flooding condition. It was confirmed that the water flooding as a mitigating action was effective to achieve the quenching and thermal stabilization of the melt discharged from the calandria vessel, showing that the present models are capable of reasonably simulating MCCI phenomena in CANDU-6 plants. This study is expected to provide the technical bases to the accident management strategy during the late-phase severe accidents.

RD-14M LOCA 실증실험 검증계산을 위한 MARS-KS 해석 모델 개발

유선오(Seon Oh Yu) 대한기계학회 2021 大韓機械學會論文集B Vol.45 No.10

원전 안전해석에 사용되는 전산코드의 예측성능은 주요 과도/사고를 모의하는 실증실험의 검증계산을 통해 평가된다. 본 연구에서는 MARS-KS 코드의 중수로 사고해석 적용 유효성 확인을 위한 코드 검증평가 기반 마련을 위해 RD-14M의 LOCA 실증실험(B9006)을 모의하는 해석 모델을 개발하였고, 실험 결과와 비교·분석하였다. 코드는 주요 실험 변수의 전반적인 열수력 거동을 유사하게 모의하였고, 계통 내 물리적 현상을 합리적으로 예측하는 것으로 평가되었다. 그리고 전산코드의 사고해석 적용 유효성 확인을 위해 코드 version 간 실증실험 예측성능 변화를 상호 비교하였다. 본 논문은 RD-14M 실증실험의 검증계산을 위한 해석 모델과 MARS-KS 코드 성능의 개선에 기여할 것으로 기대된다. The prediction performances of computational codes for safety analyses were confirmed by validation of the tests simulating the key transients/accidents of nuclear power plants. In this study, an analysis model of the RD-14M LOCA test (B9006) was developed to evaluate code validation and confirm the availability of the MARS-KS code for accident analyses of CANDU-6 plants. It was observed that the code appropriately simulated the overall thermal-hydraulic behaviors and physical phenomena of the major parameters. Moreover, to confirm the code applicability to the CANDU-6 accident analyses, the prediction variations in experiments between code versions were compared. This study is expected to contribute toward improving the analysis model and code performance for validation calculation of the RD-14M test.