• Nuclear Engineering and Technology
• /
• 제53권8호
• /
• pp.2600-2609
• /
• 2021

Low cycle fatigue behaviors of SA508-3 low-alloy steel were investigated in room-temperature air, high-temperature air and in light water reactor (LWR) water environments. The fatigue mean curve and design curve for the low-alloy steel are developed based on the fatigue data in room-temperature and high-temperature air. The environmental fatigue model for low-alloy steel is developed by the environmental fatigue correction factor (F_en) methodology based on the fatigue data in LWR water environments with the consideration of effects of strain rate, temperature, and dissolved oxygen concentration on the fatigue life.

• 한국초지조사료학회지
• /
• 제5권1호
• /
• pp.13-21
• /
• 1985

본(本) 시험(試驗)은 추파(秋播) 이탈리안라이그라스의 추계예취시취(秋季刈取時取)가 목초(牧草)의 재생(再生), 탄수화물축적(炭水化物蓄積) 및 건물수량(乾物收量)에 미치는 영향을 구명(究明)하기 위(爲)하여 포장시험(圃場試驗)을 수행(遂行)하였으며 결과(結果)를 요약(要約)하면 다음과 같다. 1. 건물수량(乾物收量)은 예취시기(刈取時期)가 빠른 구(區)일수록 높았고(P<0.05), 예취시기(刈取時期)가 제일 늦은 구(區)는 무예취구(無刈取區) 보다도 수량(收量)이 낮았다. 2. 건물중(乾物中) 전수용성탄수화물(全水溶性炭水化物)(TSC)의 함량(含量)은 일번예취직후(一番刈取直後)에 약간(若干) 떨어졌다가 재생장(再生長)에 따라 점점(漸漸) 높아졌으며 이번초(二番草) 예취기(刈取期)에 가까울수록 다시 떨어졌다. 기온(氣溫)이 영하(零下)로 하강(下降)하기 1주일전(週日前)의 TSC 함량수준(含量水準)은 그루터기, 줄기, 잎 별(別)로 모두 예취시기(刈取時期)간 빠른 구(區)일수록 고수준(高水準)이었으며 (P<0.01), 이번초(二番草)와 건물수량(乾物收量)과의 사이에 상관(相關)이 성립(成立)되었다(P<0.05) 3. 개체군(個體群) 생장속도(生長速度)(CGR)는 평균기온(平均氣溫)이 $8^{\circ}C$에서 하강(下降)할수록 떨어졌으며 상승(上昇)할수록 높았다. 상대엽면적생장율(相對葉面積生長率)(RLGR)과 순동화율(純同化率)(NAR)은 각구(各區) 모두 재생(再生)30일간(日間)이 가장 높았으며 재생후기(再生後期)에는 저하(低下)되었다. 엽면적지수(葉面積指數)(LAI)의 증대(增大)는 각구(各區) 모두 예취후(刈取後) 50일(日)까지는 빨랐으며 그 후(後)에는 완만하였고 최대치(最大値)의 범위(範圍)는 $3.4{\sim}5.8$이었다. 또한 예취후(刈取後) 70일(日)까지의 LAI가 큰 구(區)일수록 이번초(二番草)의 건물수량(乾物收量)이 높았다. 4. 생장(生長)이 억제(抑制)되는 저온기(低溫期)의 TSC, LAI ,CGR, NAR 및 LWR와 이번초건물수량(二番草乾物收量)과의 사이에 상관(相關)이 인정(認定)되엇으며, 그 공헌도(貢獻度)는 LWR>LAI>TSC>NAR>CGR의 순(順)이었다.

• 한국산림과학회지
• /
• 제100권4호
• /
• pp.598-608
• /
• 2011

본 연구는 우리나라 난대수종 중의 하나인 가시나무를 1년생 용기묘로 생산하고자 할 때 피음 및 시비처리가 용기묘의 생장과 품질에 미치는 영향을 구명하고자 실시되었다. 피음은 전광 및 전광의 35%, 55%, 75%의 수준으로 조절하였으며, 시비수준은 무시비구와 함께 수용성 복합비료(N:P:K=19:19:19, v/v)를 1000, 2000, 3000 ppm으로 조절하여 실시하였다. 본 실험을 통하여 가장 높은 간장생장은 21.1 cm를 보인 55% 피음의 2000 ppm 시비구로 조사되었으며, 근원경생장에 있어서는 35% 피음의 2000 ppm 시비구에서 3.96 mm로 가장 좋았다. 우수한 간장과 근원경생장을 보인 35%와 55% 피음에서 시비농도와 관계없이 시비구 전체 묘목의 H/D율을 보면 4.27~5.26의 범위를 보였다. 잎의 건물생산량이 가장 높은 처리구는 1.292 g을 기록한 55% 피음의 2000 ppm 시비구이었으며, 줄기와 뿌리는 각각 0.592 g과 0.998 g으로 조사된 35% 피음의 2000 ppm 시비구이었다. 묘목 전체 건물생산량은 35% 피음의 2000 ppm 시비구에서 가장 높은 생산량을 보였으며, 55% 피음의 2000 ppm, 35% 피음의 3000 ppm 시비구 순으로 높게 나타났다. 피음 및 시비처리에 따른 가시나무 LWR의 가장 높은 값은 75% 피음의 3000 ppm 시비구로 조사되었으며, RWR은 피음처리 수준에 관계없이 시비처리한 묘목이 무시비처리 묘목보다 낮았다. 전반적으로 높은 QI는 55%피음의 시비처리구들이었으며, 가장 높은 QI는 35% 피음의 2000 ppm 시비구로 조사되었다. 본 실험의 결과로 볼 때 생장이 뛰어나며 품질지수가 높은 가시나무 1년생 용기묘 생산에 적합한 피음수준은 35~55% 정도로, 시비수준은 2000 ppm이 적합한 것으로 판단된다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.291-296
• /
• 2004

Cast austenitic stainless steel piping pump, valve casings, and elbows are susceptible to reductions in toughness and ductility because of long term exposure at the operating temperatures in LWR(light water reactor). In this paper, we have measured the material properties of long term aged CF-8A cast stainless steel, accelerated aging at $400^{\circ}C$. These studies have been carried out using Indentation tests(automated ball indentation and nano-indentation) and EDS(energy dispersive spectroscopy). The fracture toughness of CF-8A cast stainless steel was also determined by using standard fracture toughness and Automated Ball Indentation.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 2004년도 추계학술발표회 발표논문집
• /
• pp.965-966
• /
• 2004

• 공학교육연구
• /
• 제15권1호
• /
• pp.45-52
• /
• 2012

The success history of Light Water Reactors (PWR and BWR) showed how a dominant technology could be shaped in a political and economical context. The american nuclear politics, the interest of american nuclear industry, and the accumulated technological know-hows made it possible that the not inherently safe reactor-Light Water Reactor- became a prominent reactor model. The path dependency of reactor technology on LWR kept the engineers from developing a new safer reactor, even if the severe reactor accidents occurred. In oder to increase safety of nuclear power system, we should understand the social shaping process of nuclear technology.

• Nuclear Engineering and Technology
• /
• 제31권6호
• /
• pp.1-7
• /
• 1999

An innovative concept for a passive reactor shutdown system, so called self-actuated shutdown system(SASS), is inevitably required for the inherent safety in liquid metal reactor, which is designed with the totally different concept from the usual reactor shutdown system in LWR. SASS using Curie point electromagnet(CPEM) was selected as the passive reactor shutdown system for KALIMER (Korea Advanced Liquid MEtal Reactor). A mock-up of the SASS was designed, fabricated and tested. From the test it was confirmed that the mockup was self-actuated at the Curie point of the temperature sensing material used in the mockup. An articulated control rod was also fabricated and assembled with the CPEM to confirm that the control rod can be inserted into core even when the control rod guide tube is deformed due to earthquake. The operability of SASS in the actual sodium environment should be confirmed in the future. All the design and test data will be applied to the KALIMER design.

• Nuclear Engineering and Technology
• /
• 제29권5호
• /
• pp.361-367
• /
• 1997

The phase separation in ferrite phase of duplex stainless steel is the primary cause of thermal aging embrittlement of the LWR primary pressure boundary components. In this study the phase separation of simulated duplex stainless steel was detected by Mossbauer spectroscopy and magnetic property analysis by VSM(Vibrating Specimen Magnetometer). The simulated duplex stainless steels, Fe-Cr binary, Fe-Cr-Ni ternary, and Fe-Cr-Ni-Si quarternary allots, were aged at 370 and 40$0^{\circ}C$ up to 5,340 hours. It was observed from Mossbauer spectra analysis that internal magnetic field increases with aging time and from VSM that the specific saturation magnetization and Curie temperature increase with aging time. These result are indicative that phase separation into Fe-rich region and Cr-rich region is caused by thermal aging in the temperature range of 370~40$0^{\circ}C$ In cases of specimens containing Ni, the increase of specific saturation magnetization is much higher. This implies that Ni seems to promote Fe-Cr interdiffusion, which accelerates the phase separation into Fe-rich $\alpha$ phase and Cr-rich $\alpha$' phase.

• 제어로봇시스템학회논문지
• /
• 제22권5호
• /
• pp.367-373
• /
• 2016

In this paper, range measurement performance of LRF (Laser Range Finder) module and image contrast of color CCD camera are evaluated under the aerosol (high temperature steam) environments, which are simulated severe accident conditions of the LWR (Light-Water-Reactor) nuclear power plant. Data of LRF and color CCD camera are key informations, which are needed in the implementation of SLAM (Simultaneous Localization and Mapping) function for emergency response robot system to cope with urgently accidents of the nuclear power plant.

• Nuclear Engineering and Technology
• /
• 제44권2호
• /
• pp.177-198
• /
• 2012

This paper reviews the fast reactor physics and computational methods. The basic reactor physics specific to fast spectrum reactors are briefly reviewed, focused on fissile material breeding and actinide burning. Design implications and reactivity feedback characteristics are compared between breeder and burner reactors. Some discussions are given to the distinct nuclear characteristics of fast reactors that make the assumptions employed in traditional LWR analysis methods not applicable. Reactor physics analysis codes used for the modeling of fast reactor designs in the U.S. are reviewed. This review covers cross-section generation capabilities, whole-core deterministic (diffusion and transport) and Monte Carlo calculation tools, depletion and fuel cycle analysis codes, perturbation theory codes for reactivity coefficient calculation and cross section sensitivity analysis, and uncertainty analysis codes.