Outlet Header Research Articles

Seismic analysis of the HIFAR nuclear reactor secondary coolant pipework and associated inlet and outlet headers

A seismic analysis was carried out to examine the integrity of the secondary coolant circuit within the reactor containment building for the HIFAR reactor located at Lucas Heights. Eigen evaluations of the structure for the first 40 modes were determined for a number of piping configurations. A response spectrum for a 0.2 g earthquake was then used to excite the structure and the resulting stresses were examined for areas of potential failure.

Characterisation of pearlitic carbide in 1Cr-0.5Mo steels

The pearlitic carbide formed during isothermal decomposition of austenite in a commercial 1Cr-0.5Mo steel has been studied using electron diffraction and energy dispersive X-ray spectroscopy. The pearlitic carbide was found to be composed of both M3C and M23C6, with the M23C6 carbide becoming more common as the transformation temperature increased. The M23C6 carbide was richer in molybdenum (2.5–6.3 at.-%) than the M3C carbide (<2.5 at.-%). The average manganese and chromium concentrations in the pearlitic M3C and M23C6 formed at a given transformation temperature were similar. The average manganese concentrations (∼ 2.5 at.-%) did not vary significantly with transformation temperature, but the chromium concentration increased from ∼ 9 at.-% at a transformation temperature of 690°C to ∼ 18at.-% at 730°C. This indicates that the initial manganese concentration in the pearlitic carbide of commercial products is unlikely to be influenced strongly by the cooling rate following austenitisation, but the chromium concentration may be more sensitive. The pearlitic carbide in exservice 1Cr-0.5Mo steels from two superheater outlet headers and a virgin 1Cr-0.5Mo steel has also been characterised to confirm that the pearlitic M23C6 carbide does occur, although not commonly, in steels subjected to commercial austenitising treatments.

Characterisation of pearlitic carbide in 1Cr-0.5Mo steels

The pearlitic carbide formed during isothermal decomposition of austenite in a commercial 1Cr-0.5Mo steel has been studied using electron diffraction and energy dispersive X-ray spectroscopy. The pearlitic carbide was found to be composed of both M3C and M23C6, with the M23C6 carbide becoming more common as the transformation temperature increased. The M23C6 carbide was richer in molybdenum (2.5–6.3 at.-%) than the M3C carbide (<2.5 at.-%). The average manganese and chromium concentrations in the pearlitic M3C and M23C6 formed at a given transformation temperature were similar. The average manganese concentrations (∼ 2.5 at.-%) did not vary significantly with transformation temperature, but the chromium concentration increased from ∼ 9 at.-% at a transformation temperature of 690°C to ∼ 18at.-% at 730°C. This indicates that the initial manganese concentration in the pearlitic carbide of commercial products is unlikely to be influenced strongly by the cooling rate following austenitisation, but the chromium concentration may be more sensitive. The pearlitic carbide in exservice 1Cr-0.5Mo steels from two superheater outlet headers and a virgin 1Cr-0.5Mo steel has also been characterised to confirm that the pearlitic M23C6 carbide does occur, although not commonly, in steels subjected to commercial austenitising treatments.

Feasibility Assessment of Potential for Parallel Flow Instability in the ITER Limiter

The ITER limiter first wall cooling system, which consists of a large number of small channels with common inlet and outlet headers, is expected to be subjected to extremely high fluxes during startup and shutdown. The potential for parallel channel two phase flow instability is examined. At the specified flow rate, the first wall system should be stable, but this conclusion depends critically on the ability to accurately predict the heat load profile. The analysis is performed assuming that all channels are subjected to the same heat loading. The situation in which the channels are subjected to different heat fluxes calls for further examination. 9 refs., 5 figs.

Creep damage of weldments in 1Cr-0.5Mo steels during long term service at elevated temperature

1. 1) The cracking of 1Cr-0.5Mo steel stub welds from the E.C.N.S.W. 3rd stage superheater outlet header occurs almost exclusively within the HAZ. The cracking is intergranular and follows prior austenite grain bo undaries. There is extensive cavitation along prior austenite grain boundaries adjacent to and ahead of these cracks. 2. 2) There is an enhanced concentration of MnS inclusions confined almost exclusively to the HAZ of those stub welds from the E.C.N.S.W. header exhibiting cracking. This is attributed to an effective “overheating” of the HAZ during weld formation, leading to dissolution and then re-precipitation of MnS particles at pr ior austenite grain boundaries during heating and cooling cycles, respectively. 3. 3) Techniques of scanning electron microscopy, and transmission electron microscopy of extraction replicas from both fracture surfaces and polished and etched sections, have been used to identify the presence of a large volume fraction of sub-micron MnS particles at prior austenite grain boundaries in the HAZ of cracked weldments. Coarse carbides have also been identified at these boundaries, the most common carbides being M 7C 3 and M 3C.

PARALLOY CR32W

Abstract PARALLOY CR32W is a cast austenitic high alloy stainless steel for applications to 1000 C (1180 F). The alloy balances high strength with good creep ductility. Typical applications include outlet headers and manifolds (pigtails) in steam methane reformers. This datasheet provides information on composition, physical properties, and tensile properties as well as creep. It also includes information on high temperature performance as well as casting. Filing Code: SS-580. Producer or source: Paralloy Ltd.

Tube Side Flow Rate Distribution in a Horizontal Multitube Heat Exchanger. 5th Report. Flow Characteristics in Tube Bundle Arranged in a Rectangular Shape.

In the previous paper, we showed that the flow rate distribution into the branch tubes from the inlet header of a 2-tube pass multitube heat exchanger which has the tube bundle arranged in a rectangular shape is markedly different from that which has the tube bundle arranged in a square shape. In the present experiment, to clarify the mechanism which causes this difference, the flow pattern in the inlet, outlet and return header of the 2-tube pass multitube heat exchanger was visualized using aluminum powder as a tracer, and the pressure distribution on the bottom wall of the inlet header was measured. The results show that the flow rate distribution is closely related to the flow pattern in the inlet header. Also, the eddy generated in the return header is strong and contains air bubbles which are never discharged.

Installation for fatigue testing during cyclic pure bending : Dolgushev, A.A., Kurteev, V.F. Dubrov, V.N. and Vasilevich, D.I. Industrial Laboratory (Russia) (Sept. 1993) 59 (3), 320–322

A finite element methodology for thermo-mechanical fatigue analysis of a subcritical power plant outlet header under realistic loading conditions is presented. The methodology consists of (i) a transient heat transfer model, (ii) a sequential anisothermal cyclic viscoplastic model and (iii) a multiaxial, critical-plane implementation of the Ostergren fatigue indicator parameter. The methodology permits identification of the local thermo-mechanical stress–strain response at critical locations and prediction of fatigue life and cracking orientation for complex transient, anisothermal, cyclic elastic–plastic-creep material behaviour. Measured plant data, in the form of steam and pipe temperature transients and steam pressure data, are employed to identify heat transfer constants and validate the predicted thermal response, with particular attention given to plant start-up and attemperation effects. The predictions indicate out-of-phase temperature-strain response at the header inside surface and in-phase response on the outside surface. Cooling transients are predicted to control damage and crack initiation at the inner bore, whereas heating transients are predicted to have a more damaging effect at weld locations. A representative test cycle is presented, which is shown to capture the salient thermo-mechanical cyclic damage of the realistic cycle. The predicted results correlate well with industrial experience in terms of crack (initiation) orientation, location and life.

Intensity and area increase of UVB/induced erythema: two variables used for studies of the influence of topically applied drugs.

The area of UV erythema produced by a small beam head was found to increase with increasing doses. The aim was to investigate whether measurement of the area could be a more useful indicator of UV-induced damage than classic visual grading. Topical pretreatment with all-trans retinoic acid (tretinoin) and betamethasone valerate was used to test the applicability of the method in pharmacological studies. We used a round outlet head (5 mm2) connected by optical fibre to a monochromatic irradiator, and doses ranging from 0.05 to 0.2 Joule of 300 mm UV light were applied to the skin of 6 healthy subjects. Erythemal area was calculated by the measurement of two diameters, and intensity was graded visually (0-6 scale). The area of the erythema correlated with the increase in intensity up to score 6. Area measurement was less subject to intra-investigators' variability than the intensity score. By multiplying intensity by area, a good indicator of UV-induced reactivity was obtained. Pretreatment with betamethasone valerate decreased the area of erythema, as did tretinoin 12 h after irradiation. Thus, area measurement of erythema is a useful adjunct to visual grading of UV-induced skin reactions.

4961851 Self-cleaning reverse osmosis liquid treatment system, method and dual configuration check valve therefor

A self-cleaning reverse osmosis liquid treatment system, method of cleaning a reverse osmosis membrane, and a dual configuration flow check valve for inlet and outlet heads of such a system. The system includes at least two membrane vessels each having at least one reverse osmosis membrane contained therein. One vessel processes intake liquid such as sea water, ground water or other fluids or juices into product liquid in the normal way, having a waste liquid discharge, while the other vessel simultaneously undergoes cleansing. Product liquid discharging from the vessel processing the product liquid is redirected at lower pressure back through an additional inlet in the inlet head having one check valve in its normally closed configuration positioned in the inlet head of the vessel being cleansed. Another check valve in a normally opened configuration in the outlet head of the vessel being cleansed cooperatively acts with the normally closed check valve in the inlet head to allow all liquid as product liquid to exit the cleansing vessel to a storage tank for later use. The flow of product liquid through the membrane being cleaned is at low pressure so that very little further reverse osmosis activity occurs in the membrane being cleansed and descaled. The check valves act in unison to close upon the introduction of intake liquid into the vessel at higher pressure to activate the cleansed membrane then ready for reuse.

LOCA assessment experiments in a full-elevation, CANDU-typical test facility

The RD-14 thermal-hydraulics test facility, located at the Whiteshell Nuclear Research Establishment, is a full-elevation model representative of a CANDU primary heat transport system. The facility is scaled to accommodate a single, full-scale (5.0 MW, 21 kg/s), electrically heated channel per pass. The steam generators, pumps, headers, feeders and heated channels are arranged in a typical CANDU figure-of-eight geometry. The loop has an emergency coolant injection system (ECI) that may be operated in several modes, including typical features of the various ECI systems found in CANDU reactors. A series of experiments has been performed in RD-14 to investigate the thermal-hydraulic behaviour during the blowdown and injection phases of a loss-of-coolant accident (LOCA). The tests were designed to cover a full range of break sizes from feeder-sized breaks to guillotine breaks in either an inlet or an outlet header. Breaks resulting in channel flow stagnation were also investigated. This paper reviews the results of some of the LOCA tests carried out in RD-14, and discusses some of the behaviour observed. Plans for future experiments in a multiple-channel RD-14 facility, modified to contain multiple flow channels, are outlined.

4797091 Method and apparatus for utilizing the heat energy of domestic and commercial refuse

The invention relates to a method for utilizing the heat energy of domestic and commercial refuse in a rotary kiln installation. The prepared crude refuse is degassed in a pyrolysis reactor and the pyrolysis gas produced is delivered to the main burner of the rotary kiln, optionally using primary fuel. For optimum and economic production of the pyrolysis gas crushed refuse is dried pneumatically with the aid of exhaust air from the cooler and is delivered to the pyrolysis reactor. The pyrolysis reactor is heated indirectly to a low temperature with hot secondary air from the kiln outlet head and the pyrolysis gas produced is delivered together with used secondary air to the main burner of the kiln.

CANDU-600 Heat Transport System Flow Stability

The thermohydraulic stability of the Canada deuterium uranium (CANDU)-600 heat transport system was investigated from a theoretical, numerical, and experimental point of view. Simple theoretical models, used to provide phenomenological insight as a guide to the numerical and experimental studies, showed that a major form of positive feedback existed through an interplay of circuit flow, outlet header void fraction, and outlet header pressure. The flow and pressure dynamics proved to be good indicators of system stability. System computer codes (SOPHT, FIREBIRD, and HYDNA) were used for the detailed modeling of system dynamics. These codes showed that neither Ledinegg nor parallel channel instabilities occur in CANDU-600 nuclear reactors. Loop stability was predicted under all conditions with the reactor outlet header interconnect line in service as designed. With the interconnect line disconnected, loop instability was predicted for a narrow outlet header quality range ( 1 to 8%). These predictions were fully confirmed by semiscale experimental loop tests and plant commissioning tests.

Cablegation: V. Dimensionless Design Relationships

ABSTRACT Asimplified design method using dimensionless relationships was developed for the cablegation automated surface irrigation system. The method consists of two parts: the pipe flow distribution and the infiltration-runoff distribution. The maximum outlet head, maximum stream size and number of flowing outlets are calculated using a set of dimensionless equations, given the pipe size, pipe slope, outlet size and spacing and total inflow rate. These equations enable a direct determination of the design variables without calculating the entire distribution of outlet flows. If the desired maximum stream size is known, the required outlet size can be calculated directly without trial and error. The infiltration-runoff analysis is presented as a series of dimensionless relationships in graphical form. These curves are used mainly for determining the required maximum stream size given a time-based furrow intake curve, furrow length and spacing, gross water application and percent runoff. Curves are also presented for the case of constant stream size for comparison with cablegation and for use in designing constant-inflow irrigation systems..

Flow Distribution in Parallel Connected Manifolds for Evacuated Tubular Solar Collectors

A model is presented for predicting the flow distribution in solar collector manifolds in which risers are connected in parallel between headers. Both frictional and Bernoulli effects are considered. The distributions resulting from flow in the manifold in which header streams are parallel and opposed are calculated and compared with experiment. Parallel flow gives a more uniform distribution. The outlet header is found to be more critical in balancing the flow distribution than the inlet header. Conditions under which thermosiphon effects are important and flow reversal in risers may occur are discussed with reference to experiment.

Hydrodynamic Instability in a Full-Scale Simulated Reactor Channel

An experimental programme has been carried out to investigate parallel-channel instability in a full-scale simulated nuclear reactor channel operating in vertical high-pressure boiling-water upflow. Experimental data have been obtained using a vertically mounted test section containing two 19-rod electrically heated bundles with a total heated length of 195 in. The test section was operated in parallel with an unheated by-pass between common inlet and outlet headers. The characteristics of the observed test-section and by-pass flow oscillations are described in detail. Data are presented showing the effect upon test section flow stability of bundle electrical power, inlet subcooling, operating pressure, feeder pressure loss coefficients and the ratio of by-pass flow-rate to test-section flow-rate.

Flow Distribution in Forced-Circulation Once-Through Steam Generators

Abstract Forced-circulation, once-through steam generators of large capacity are constructed of several parallel circuits connected between inlet and discharge headers. Unequal flow distribution between these circuits, possibly resulting in tube failure, may be due to unequal frictional resistances, unequal heat absorption, or improper arrangements of circuits. The investigation which is reported in this paper was undertaken in order to determine the effect of unequal heat absorption, unequal circuit resistances, and the location of equalizers upon the flow distribution in the circuits of forced-circulation steam generators. Pressure-drop calculations were based on the measurement of friction factors of water at temperatures between 57 and 694 F; also, of superheated steam at pressures between 1120 and 3578 lb per sq in abs with a maximum temperature of 806 F. Head-loss measurements were made with a special glass manometer for pressures up to 2200 lb per sq in., and for higher pressures by radiographs of the mercury level in a steel-tube manometer. An analysis of flow distribution between parallel circuits leads to the following conclusions: (1) Parallel circuits connected between the feedwater header and the superheater outlet header are unstable, the pressure drop being nearly independent of the flow rate. Consequently, slight variations in frictional resistance or heat-transfer rates may result in decreased flow and in overheated tubes. (2) The flow in unstable circuits can be controlled by the use of an inlet resistance such as a section of small-diameter tube. (3) The use of a common header or equalizer on each side of the evaporating zone will stabilize the flow in parallel circuits. (4) Superheater and economizer circuits are more stable than evaporating-zone circuits. (5) If only one equalizer is used, it should be placed at the end of the economizer section rather than at the end of the evaporating surface. (6) The stability of circuits is independent of their capacity. (7) The stability of superheater circuits is independent of pressure. Combined evaporating zone and superheater circuits are more stable at high pressures. Curves are presented to show the extent to which the enthalpy of the steam and of the water delivered from parallel circuits will vary as a result of unequal circuit resistances and unequal heat absorption.