分类： 核科学技术 >> 裂变堆工程技术 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： The safety analysis code SCTRAN for SCWR (Super Critical Water Reactor) is modified to own the capability to assess the radiation heat transfer with developing a two-dimensional heat conduction solution scheme and incorporating a radiation heat transfer model. The verification of the developed radiation heat transfer model is conducted through code-to-code comparison with CATHENA. The results show that the modified SCTRAN code is successful for that the maximum absolute error and relative error of the surface temperature between results of SCTRAN and CATHENA are 6.1 ℃ and 0.9%, which are acceptable in temperature prediction. Then, with the modified SCTRAN code, the loss of coolant accident with a total loss of emergency core cooling system (LOCA/LOECC) of Canadian-SCWR is carried out to evaluate its no-core-melt concept. The following conclusions are achieved: 1) in the process of LOCA, the decay heat can be totally removed by the radiation heat transfer and the natural convection of the high-temperature coolant, even without an intervention of ECCS (Emergency Core Cooling System); 2) The peak cladding temperature of the fuel pins in the inner and outer rings of the high power group are 1236 ℃ and 1177 ℃ respectively, which are much lower than the melting point of the fuel sheath. It indicates that the Canadian-SCWR can achieve no-core-melt concept under LOCA/LOECC.
分类： 物理学 >> 核物理学 提交时间： 2016-08-30
摘要： Quasi-periodic oscillation (QPO) detected in the X-ray radiation of black hole X-ray binaries (BHXBs) is thought to originate from dynamical processes in the close vicinity of the black holes (BHs), and thus carries important physical information therein. Such a feature is extremely rare in active galactic nuclei (AGNs) with supermassive BHs. Here we report on the detection of a possible X-ray QPO signal with a period of 3800\,s at a confidence level >99.99% in the narrow-line Seyfert 1 galaxy (NLS1) 1H~0707-495 in one data set in 0.2-10\,keV taken with {\it XMM-Newton}. The statistical significance is higher than that of most previously reported QPOs in AGNs. The QPO is highly coherent (quality factor Q=ν/Δν⩾15) with a high rms fractional variability (∼15%). A comprehensive analysis of the optical spectra of this AGN is also performed, yielding a central BH mass 5.2×106M⊙ from the broad emission lines based on the scaling relation. The QPO follows closely the known frequency-BH mass relation, which spans from stellar-mass to supermassive BHs. The absence of the QPO in other observations of the object suggests it a transient phenomenon. We suggest that the (high-frequency) QPOs tend to occur in highly accreting BH systems, from BHXBs to supermassive BHs. Future precise estimation of the BH mass may be used to infer the BH spin from the QPO frequency.
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