Horizontal Leg Research Articles

Investigation of Break Orientation Effect during Cold Leg Small-Break LOCA at ROSA-IV LSTF

The Large Scale Test Facility (LSTF) of the Rig-of-Safety Assessment No. 4 (ROSA-IV) Program is a volumetrically scaled (1/48) pressurized water reactor (PWR) system with an electrically heated core used for integral simulation of small break loss-of-coolant accidents (SBLOCAs) and operational transients. Three 2.5% cold-leg SBLOCA experiments were conducted at LSTF. In the experiments, the break was oriented at the side, bottom and top of the horizontal cold leg, respectively. The loop seal clearing in the bottom break case was later than in the side break case since a larger amount of liquid had to be discharged until the loop seal clearing. The loop seal clearing in the top break case was later than in the side break case because of the smaller discharge flow rate. The core liquid level drop due to boiloff after the loop seal clearing in the bottom break case was earliest among three cases because of the largest mass loss before the loop seal clearing and in the top break case latest because of the latest occurrence of the loop seal clearing. However, the effect on the system transients such as the pressure and core liquid level transients was small since the transient time was quite long. Analyses to the experimental results were performed with the RELAP5/MOD2 code. Shortcomings in the RELAP5 code calculation results were resolved by reducing the interfacial drag in the hot leg and the core. The inclusion of Shrock's model for the side, bottom and top break of a large horizontal pipe was also tested in the analyses. However, consistent results with data were not obtained since the void fraction in the broken cold leg was not calculated properly.

Investigation of break orientation effect during cold leg small-break LOCA at ROSA-IV LSTF.

The Large Scale Test Facility (LSTF) of the Rig-of-Safety Assessment No. 4 (ROSA-IV) Program is a volumetrically scaled (1/48) pressurized water reactor (PWR) system with an electrically heated core used for integral simulation of small break loss-of-coolant accidents (SBLOCAs) and operational transients. Three 2.5% cold-leg SBLOCA experiments were conducted at LSTF. In the experiments, the break was oriented at the side, bottom and top of the horizontal cold leg, respectively. The loop seal clearing in the bottom break case was later than in the side break case since a larger amount of liquid had to be discharged until the loop seal clearing. The loop seal clearing in the top break case was later than in the side break case because of the smaller discharge flow rate. The core liquid level drop due to boiloff after the loop seal clearing in the bottom break case was earliest among three cases because of the largest mass loss before the loop seal clearing and in the top break case latest because of the lat...

Appliance for purifying water

A small portable appliance for purifying potable water. A vertical "C" shaped body supports a purified water container on its lower horizontal leg. The rearward portion of the body's vertical back releasably carries a filtration cartridge defining three separate intercommunicating chambers replaceably carrying a pre-filter cartridge, an osmotic filter cartridge and a carbon post-filter cartridge. Control circuitry shuts off water input when the purified water container is full, senses and annunciates the amount of dissolved solids in effluent water and measures use time to annunciate estimated time for filter cartridge change. Internal structure provides storage for a removable connector tube.

On the stability and flow reversal of an asymmetrically heated open convection loop

Experimental results are reported for a U-shaped, free convection loop. The top of the loop is open to an isothermal reservoir. The horizontal leg and one vertical leg are heated at rates Q1 and Q2, respectively. The loop is filled either with water or a water-saturated porous medium. Symmetric heating and asymmetric heating favouring the ascending leg of the loop both yield stable flows. Asymmetric heating favouring the descending leg leads to stable flows when the ratio Q1/Q2 is above a critical value. Below this critical value, the flow is observed to oscillate with increasing amplitude until the direction of flow in the loop undergoes a reversal. A steady flow follows the reversal. Analytical results include a stability analysis and time-dependent, one-dimensional numerical calculations, both of which compare favourably with experiment.The disturbance amplification mechanism is explained in terms of thermal anomalies which move through the loop with the material motion of the fluid. Since the heating and buoyancy generation processes are in phase in the heated, descending leg, a thermal anomaly can amplify as it flows through that leg. As the anomaly moves through the ascending leg, it initiates a subsequent anomaly of opposite sign in the descending leg. The result is an oscillating flow which, under appropriate conditions, can amplify.

Ａｌ‐Ｓｉ系ろうの組成および組織とアルミニウムのろう付性

Brazability of aluminum T-joint (AA 1100) was evaluated by a fillet formation test in vacuum. The crosssection fillet leg length ratio LV/LH (LV: vertical leg length, LH: horizontal leg length) was used for evaluating the brazability, where the ratio approaches unity under a good brazing condition. A sound fillet can be achieved at the melting temperature range of filler alloys. LV/LH reaches a plateau beyond this temperature by isothermal solidification which starts at a fillet edge. Filler alloys containing fine silicon particles are preferable to ensure succesful fillet shape. Iron up to 1.4% in Al-10%Si filler alloy has no influence on the brazability.

An Analysis of Turns in Dance

Turns are an important part of dance vocabulary. Turns in place on one foot — pirouettes, attitude turns, and turns in arabesque, for instance — form a category of ballet movements that are difficult to learn well, and require considerable skill in control of the body.Three characteristics of turns are important in the proper execution of the movement: body form, rate of turn, and balance. The aesthetic body form can be learned only by example and by careful criticism from a dance teacher. Turnout of the supporting foot or a straight horizontal leg in anarabesque turn are important aspects of a good turn in a purely artistic sense. But other properties of a turn, the most important of which are rate of turn and balance, are open to physical analysis, an understanding of which may give the dancer and dance teacher a better sense of the turning process.Three considerations addressed here are the importance of the distribution of body mass around the rotation axis, the way the torque for the turn is exerted and angular momentum generated, and the way a dancer maintains balance over a supporting point. In order to investigate more carefully the way a dancer initiates a turn by exerting a torque on the floor, experiments were carried out in which this torque, and the resulting angular momentum of the dancer, could be measured.

アルミニウムの真空ろう付 エメリー紙研摩の影響

Vacuum brazing of aluminum with BA 4047 filler alloy can be performed by the inserted type brazing in which filler alloy is preinserted between the vertical and horizontal members. Grinding by emery papers of 80-600 grade is suitable for the surface treatment of aluminum vacuum brazing. Obtained results are summarized as follows. (1) The ratio of vertical leg length (LV) against horizontal leg length (LH), LV/LH, is convinient and clear for the estimation of brazability (ability of fillet formation). (2) Grinding by fine emery papers led contamination of ground surface by including the emery paper component SiC. Sound fillet was not formed by grinding with 1500 grade emery paper which retained much inclusion on treated surface. Sound fillet was obtained by grinding 80-600 grades emery papers in which little inclusion was observed. Poor fillet formation is attributable to the scarce reactivity of SiC with melted Al-Si filler alloy. (3) Pertinent pretreatment of base metal is important for the sound fillet formation, especially the vertical member should react rapidly with melted filler alloy. (4) Clear correspondence is not found between the spraedability and the fillet formation.

Cesium-graphite sorption isotherms determined by a static method

The Sorption of cesium by nuclear-grade graphite in the temperature range 800° to 1100°C and at partial pressures of 1 × 10 −8 to 7× 10 −3 atm has been determined by static method. Approximately 0.5 g of graphite, having a known BET surface area, is placed in the horizontal leg of a Pyrex-stainless steel, L-shaped, evacuated tube, and cesium metal tagged with 137Cs is distilled into the other leg. The entire system is thoroughly outgassed and sealed off at a pressure of ~10 −5 mm Hg. During a run the cesium pressure is fixed by maintaining the cesium metal source at a constant temperature. The amount of cesium on the graphite specimen is monitored with a calibrated gamma scintillation counter until an equilibrium condition has been established at the desired specimen temperature and cesium pressure. The data obtained indicate chemisorption at concentrations below that corresponding to a monolayer of coverage of internal (BET) surface area. Under these conditions, the cesium pressure has been found to be proportional to the cesium concentration to the nth power, where n is approximately 3–6, depending on temperature. Isosteric heats of sorption are of the order of 40–90 kcal/mole, depending on concentration. More complex isotherms and less strong sorption are found for concentrations corresponding to greater than a monolayer of coverage.