• Nuclear Engineering and Technology
• /
• 제56권3호
• /
• pp.973-979
• /
• 2024

In the framework of the Generation IV research and development project, in which the French Commission of Alternative and Atomic Energies (CEA) is involved, a main objective for the design of Sodium-cooled Fast Reactor (SFR) is to meet the safety goals for severe accidents. Among the severe ones, the Unprotected Transient OverPower (UTOP) accidents can lead very quickly to a global melting of the core. UTOP accidents can be considered either as slow during a Control Rod Withdrawal (CRW) or as fast. The paper focuses on fast UTOP accidents, which occur in a few milliseconds, and three different scenarios are considered: rupture of the core support plate, uncontrolled passage of a gas bubble inside the core and core mechanical distortion such as a core flowering/compaction during an earthquake. Several levels and rates of reactivity insertions are also considered and the thermal-mechanical behavior of an ASTRID fuel pin from the ASTRID CFV core is simulated with the GERMINAL code. Two types of fuel pins are simulated, inner and outer core pins, and three different burn-up are considered. Moreover, the feedback from the CABRI programs on these type of transients is used in order to evaluate the failure mechanism in terms of kinetics of energy injection and fuel melting. The CABRI experiments complete the analysis made with GERMINAL calculations and have shown that three dominant mechanisms can be considered as responsible for pin failure or onset of pin degradation during ULOF/UTOP accident: molten cavity pressure loading, fuel-cladding mechanical interaction (FCMI) and fuel break-up. The study is one of the first step in fast UTOP accidents modelling with GERMINAL and it has shown that the code can already succeed in modelling these type of scenarios up to the sodium boiling point. The modeling of the radial propagation of the melting front, validated by comparison with CABRI tests, is already very efficient.

• 대기
• /
• 제31권5호
• /
• pp.563-576
• /
• 2021

The performance of East Asian summer monsoon is assessed for GC2 and GC3.1, which are climate change models of the current and next climate prediction system in the Korea Meteorological Administration (KMA), GloSea5 and GloSea6. The most pronounced characteristics of GC models are strong monsoon trough and the weakening of the Western North Pacific Subtropical High (WNPSH). These are related to the weakening of the southwesterly wind and resulting weak monsoon band toward the Korean Peninsula. The GC3.1 is known to have improved the model configuration version compared to GC2, such as cloud physics and ocean parameters. We can confirm that the overall improvements of GC3.1 against GC2, especially in pressure, 850 hPa wind fields, and vertical wind shear. Also, the precipitation band stagnant in the south of 30°N in late spring is improved, therefore the biases of rainy onset and withdrawal on the Korean Peninsula are reduced by 2~4 pentad. We also investigate the impact of initialization in comparison with GloSea5 hindcast. Compared with GCs, hindcast results show better simulation within 1 month lead time, especially in pressure and 850 hPa wind fields, which can be expected to the improvement of WNPSH. Therefore, it is expected that the simulation performance of WNPSH will be improved in the result of applying the initialization of GloSea6.

• 정신신체의학
• /
• 제16권2호
• /
• pp.69-74
• /
• 2008

섬망은 의식의 장애와 인지 증상이 급성 발병을 하며 변동하는 경과를 보여주는 기질적인 정신과 증후군이다. 임상적 아형을 이상적으로 분류하기 위한 도구는 없지만 Lipowski(1983)가 섬망의 아형을 정신운동의 활동성을 기준으로 과활동성, 저활동성, 혼재성으로 분류한 이래로 연구자들 마다 다양한 도구를 이용하여 섬망의 아형을 임상적으로 구분하여 왔다. 그 연구 결과에 의하면 저활동성 섬망의 유병율이 과활동성 섬망에 비하여 오히려 많거나 적지 않은 것으로 보고되고 있지만 증상의 특성 때문에 저활동성 섬망의 임상적 진단이 적게 이루어지거나 우울증이나 치매 등으로 오인되는 경향을 보였다. 과활동성 섬망은 알코올 또는 벤조디아제핀 금단등에 의해 유발되며 도파민 과잉과 아세틸콜린의 결핍과 관련이 있으며 고역가 항정신병약물에 반응이 좋아 다른 아형에 비하여 예후가 양호한 반면에 저활동성 섬망은 대사성 뇌병증에 의한 경우가 흔하며 고역가 항정신병약물에 의한 반응이 예상보다 좋지 않는 경우가 있으며 임상적으로 정신자극제 치료가 효과적이라는 보고가 되고 있다. 입원 기간도 더 길고 인지 증상도 심하여 전반적으로 예후가 좋지 못한 경향이 있다. 섬망은 아형을 갖는 이질적인 증후군이다. 아형이 존재한다는 것은 아마도 각기 다른 기전에 의할 가능성을 시사하며 따라서 아형에 따라 구별되는 치료 전략이 필요할 것이다.

• International Journal of Oral Biology
• /
• 제34권1호
• /
• pp.1-6
• /
• 2009

The purpose of the present study was to examine the role of peripheral nitric oxide (NO) pathways in the onset of interleukin (IL)-1$\beta$-induced mechanical allodynia in the orofacial area. Experiments were carried out on male Sprague-Dawley rats weighing 230-280 gm and surgical procedures were performed under pentobarbital sodium (40 mg/kg, i.p.). Under anesthesia, a polyethylene tube (PE10) was implanted into the subcutaneous area of one vibrissa pad, which enabled the injection of IL-1$\beta$ or other chemicals. We subcutaneously injected 50 ${\mu}L$ of IL-1$\beta$ into a vibrissa pad through the implanted polyethylene tube with a 100 ${\mu}L$ Hamilton syringe. After the administration of 0.01, 0.1, 1, or 10 pg of IL-1$\beta$, withdrawal behavioral responses were examined. The subcutaneous injection of saline had no effects on the air-puff thresholds. Following the subcutaneous injection of 0.01, 0.1, 1, or 10 pg of IL-1$\beta$, the threshold of air puffs decreased significantly to 12 $\pm$ 3, 7 $\pm$ 2, 5 $\pm$ 1, or 5 $\pm$ 1 psi, respectively, in a dose dependent manner. Pretreatment with L-NAME, a nitric oxide synthase (NOS) inhibitor, blocked IL-1$\beta$-induced mechanical allodynia. However, neither D-NAME, an inactive isomer of L-NAME, nor vehicle affected the IL-1$\beta$-induced mechanical allodynia. Subcutaneous injection of IL-1$\beta$ increased the number of c-fos-like immunoreactive neurons, whereas pretreatment with L-NAME decreased this number, in the trigeminal caudal nucleus. These results suggest that pro-inflammatory cytokines and NO are important contributors to the pathogenesis of persistent and exaggerated IL-1$\beta$-induced pain states. Based on these observations, peripheral application of NOS inhibitors may be of therapeutic value in treating pain disorders in the clinic.