用LG55冷轧管机轧制小直径不锈钢管孔型改进

介绍了ＬＧ５５冷轧管机使用Φ７～３２ｍｍ、Φ５０～３２ｍｍ孔型轧制小直径不锈钢管的工艺特点。试验表明，两种孔型可行，且Φ５７～３２ｍｍ孔型的综合使用效果更好。     

混凝土小砌块与普通砖混住宅楼造价分析

指出混凝土小型空心砌块是一种节能型的新型墙体材料。本文从经济角度对该种材料和粘土砖材料进行了实例分析、比较,得出了这种新型材料值得推广使用的结论。     

论《小企业会计制度》的特点

比较了《小企业会计制度》与《企业会计制度》在会计核算规定方面的差异，总结了《小企业会计制度》的特点。     

Small PWRs using coated particle fuel for district heating, PFPWR50

It has been said that nuclear energy is an important option for especially developing countries to satisfy their increasing energy demand. However, it will be difficult to deploy first of a kind nuclear power plant in developing countries because extensive safety demonstration has to be conducted in industrialized countries. On the other hand, it will be essential to present rigid proof of reliable operational experience to develop proper understanding of the safety features of new reactor systems among the people around the demonstration plant sites. One of the ways to solve the issue is to integrate existing technologies supported by a great deal of data and experience into a new reactor design. Based on the consideration, a small-sized district heating reactor system based on the pressurized water reactor (PWR) technologies combined with the fuel concept of high temperature gas cooled reactors (HTGRs) has been studied. The purpose of the combination of these two existing concepts is to take the best advantages of both excellent operational experience of PWRs and the integrity of HTGR fuel, coated particle fuel, against fission products release even at high temperature. We expect that this approach will help create a breakthrough to the current stagnation of nuclear power deployment.     

Effects of reaction temperature and inlet oxidizing gas flow rate on IG-110 graphite oxidation used in HTR-PM

The oxidation behavior of a selected nuclear graphite (IG-110) used in Pebble-bed Module High Temperature gas-cooled Reactor was investigated under the condition of air ingress accident. The oblate rectangular specimen was oxidized by oxidant gas with oxygen mole fraction of 20% and flow rates of 125–500 ml/min at temperature of 400–1200?°C. Experiment results indicate that the oxidation behavior can also be classified into three regimes according to temperature. The regime I at 400–550?°C has lower apparent activation energies of 75.57–138.59 kJ/mol when the gas flow rate is 125–500 ml/min. In the regime II at 600–900?°C, the oxidation rate restricted by the oxygen supply to graphite is almost stable with the increase of temperature. In the regime III above 900?°C, the oxidation rate increases obviously with the increase of temperature. With the increase of inlet gas flow from 125 to 500 ml/min, the apparent activation energy in regime I is increased and the stableness of oxidation rate in regime II is reduced.     

Neutron poison distribution in the central reflector to reduce the DLOFC temperature of a Th-LEU fueled OTTO PBMR DPP-400 core

In a previous study using a mixture of thorium and 20 a/o% LEU at 16 gram per fuel sphere heavy metal loading and adjusting the effective fuel enrichment to produce the same amount of cumulative energy per fuel sphere as with the 10 a/o% Low Enriched Uranium (LEU), the maximum Depressurized Loss Of Forced Cooling (DLOFC) temperature was reduced from 2273 to 1925 °C and 1811 °C for a symmetric and asymmetric core, respectively using an once-through-then-out (OTTO) fuelling scheme. This article presents an additional strategy for reducing the maximum DLOFC temperature by placing an optimized distribution of neutron poisons in the central reflector. This strategy produced maximum DLOFC temperatures of 1509 and 1448 °C for the symmetric and the asymmetric cores, respectively. These results are impressive as it means that the less complicated OTTO cycle with its lower capital cost achieved the same cumulative energy produced per fuel sphere than the standard six-pass refuelling scheme and that at substantially lower maximum DLOFC temperatures. Both the addition of the neutron poisons to the central reflector and the creation of a radially asymmetric core resulted in lower burn-ups that had to be reversed by increasing the enrichment of the fuel.     

Using thorium to reduce the maximum fuel temperatures during depressurized loss of coolant accidents in a once-through-then-out (OTTO) PBMR DPP-400 core

This article presents the results for the PBMR-DPP-400, but for a once-through-then-out (OTTO) refueling scheme. An optimization attempt of the axial and radial power profiles is reported. The main aim was to reduce the maximum depressurized loss of forced coolant (DLOFC) temperature by adding thorium to the fuel and making the fuel layout radially asymmetric by placing lower enriched fuel in the inner and higher enriched fuel in the outer fuel flow regions. These measures (1) flattened the peaks in the axial power profiles and thus suppressed the hotspots in the axial DLOFC temperature profiles and (2) ‘pushed’ the power radially outwards, so as to reduce the distance that the decay heat must be evacuated towards the outside of the fuel core. This resulted in a huge reduction in the maximum DLOFC temperature for the OTTO cycle from 2273 to 1811 °C, which is still above the 1600 °C limit but represents a remarkable result. Maximum DLOFC temperature below the 1600 °C limit was obtained by reducing the power output. The results obtained and the proposed strategies for further improvement are applicable to the Chinese HTR-PM and could produce even better results in Prismatic Block Reactors such as the Japanese HTTR.     

Effect of Delays in Afterheat Removal on Consequences of Massive Air Ingress Accidents in High-Temperature Gas Cooled Reactors

Massive ingress of air into the core of a high-temperature gas cooled reactor is among the accidents with a low occurrence frequency, but there are still gaps in understanding with respect to its consequences. In the present paper, massive air ingress combined with a delayed start of the afterheat removal system is investigated and compared to air ingress, accidents with normal operation of the afterheat removal procedure. A computer programme REACT/THERMIX used for these accident analyses is described. For a high-temperature gas cooled reactor with a pebble bed core, it is shown that massive air ingress has no real safety endangering consequences even if the operation of the afterheat removal system is delayed by 6 h.     

拔销器的小型化设计

介绍了一种拔销器的设计,从结构和装药设计实现拔销器小型化,对装药和回缩力进行了估算,用冗余试验验证产品设计及装药可靠性,结果表明发火与输出可靠度R＞0.995 3(置信度0.90).     

Positron annihilation and nano-indentation analysis of irradiation effects on the microstructure and hardening of A508-3 steels used in Chinese HTGR

The irradiation and annealing behavior of Chinese A508-3 reactor pressure vessel (RPV) steel (0.04 wt% Cu) after 3 MeV Fe-ion irradiation ranging from 0.1 to 20 dpa at room temperature (called RTRPV) and high temperature (250?°C, called HTRPV) was studied by positron annihilation Doppler broadening (PADB) spectroscopy and nano-indentation hardness. PADB showed that the density of vacancy-type defects was higher for low-temperature irradiations. The higher hardness was found after high-temperature irradiation because of the formation of solute clusters during irradiation. Positron annihilation measurements revealed the interaction and clustering of vacancies with solute clusters which were introduced by Fe-ion irradiation. For both RTRPVs and HTRPVs, the positron defect parameter and positron diffusion length showed the recovery of the irradiation-induced defects. Total recovery was observed after annealing at 450 °C.