Drain Tank Research Articles

Startup Thermal Considerations for Supercritical-Pressure Light Water-Cooled Reactors

Supercritical-pressure light water-cooled reactors (SCRs) are innovative systems aimed at high efficiency and cost reduction. The once-through direct-cycle plant system is the leading system of fossil-fired power plants (FPPs). Estimates of the coolability and necessary sizes of the SCR startup systems, sequences, and required equipment for startup are investigated with reference to supercritical FPPs. There are two types of supercritical boilers. One is a constant pressure boiler, and the other is a variable pressure boiler.First, startup of the constant pressure boiler is examined. The reactor starts at a supercritical pressure. A startup bypass system consisting of a flash tank and pressure-reducing valves is required. Second, startup of the variable pressure boiler is investigated. The reactor starts at a subcritical pressure, and the pressure increases with the load. A steam-water separator and a drain tank are required for startup.The results of computer calculations show that with both constant pressure and variable pressure startup, the peak cladding temperature does not exceed the operating limit through startup, and both startup sequences are feasible. The sizes of the components required for the startup systems are assessed. To simplify the plant system and to reduce the component size, variable pressure startup with steam separators in the bypass line appears desirable.

Anopheline (Diptera:Culicidae) breeding in a traditional tank-based village ecosystem in north central Sri Lanka.

A 13-mo survey of immature anopheline mosquitoes breeding in surface water habitats was done at Mahameegaswewa village within the Huruluwewa watershed in north central Sri Lanka as part of a multidisciplinary study on malaria epidemiology. The watershed is representative of the ancient small tank-based irrigation network that still forms an important component of the rice production system in the low elevation dry zone. In total, 3,818 immatures representing 12 species were obtained from 2,940 samples taken from 5 larval habitats within the village ecosystem. Anopheles varuna Iyengar and An. culicifacies Giles were the most abundant species collected. Peak abundance in both species occurred in August-October. Anopheles barbirostris Van der Wulp and An. peditaeniatus Leicester also were abundant, but neither these nor the other anophelines attained comparable abundance to An. varuna and An. culicifacies. A clear progression in breeding habitat use from stream bed to tank bed and drainage area pools was seen in An. culicifacies during the premonsoon period. Environmental management measures to reduce or modify these habitats could potentially decrease malaria. transmission.

An outbreak of gastroenteritis and fever due to Listeria monocytogenes in milk.

After an outbreak of gastroenteritis and fever among persons who attended a picnic in Illinois, chocolate milk served at the picnic was found to be contaminated with Listeria monocytogenes. In investigating this outbreak, we interviewed the people who attended the picnic about what they ate and their symptoms. Surveillance for invasive listeriosis was initiated in the states that receive milk from the implicated dairy. Stool and milk samples were cultured for L. monocytogenes. Serum samples were tested for IgG antibody to listeriolysin O. Forty-five persons had symptoms that met the case definition for illness due to L. monocytogenes, and cultures of stool from 11 persons yielded the organism. Illness in the week after the picnic was associated with the consumption of chocolate milk. The most common symptoms were diarrhea (present in 79 percent of the cases) and fever (72 percent). Four persons were hospitalized. The median incubation period for infection was 20 hours (range, 9 to 32), and persons who became ill had elevated levels of antibody to listeriolysin O. Isolates from stool specimens from patients who became ill after the picnic, from sterile sites in three additional patients identified by surveillance, from the implicated chocolate milk, and from a tank drain at the dairy were all serotype 1/2b and were indistinguishable on multilocus enzyme electrophoresis, ribotyping, and DNA macrorestriction analysis. L. monocytogenes is a cause of gastroenteritis with fever, and sporadic cases of invasive listeriosis may be due to unrecognized outbreaks caused by contaminated food.

Drum filter performance in a recirculating eel culture unit

The performance of a drum filter of a recirculating eel culture unit was studied. Electron microscopy scanning micrographs of drum filter panels showed a high degree of clogging of the filter mesh (after 4 months of operation). Mean removal efficiency for Total Suspended Solids (TSS) fluctuated considerably between subsequent sampling periods (9.6–18.4%). Drum filtration changed the particle size distribution of fish tank drainage water, resulting in increasing amounts (from 56 to 67% of dry weight, before and after filter passage) of the smaller particle fractions (< 20 μm), thereby indicating a partial breakdown of larger particles during the filtration process. Possible reasons for rapid filter clogging and suggestions for improvements in filter performance are discussed.

Modeling Disinfectant Residuals in Drinking-Water Storage Tanks

The factors leading to the loss of disinfectant residual in well-mixed drinking-water storage tanks are studied. Equations relating disinfectant residual to the disinfectant's reaction rate, the tank volume, and the fill and drain rates are presented. An analytical solution for the minimum disinfectant residual in the tank under constant inflow/outflow conditions is found. It shows that significant disinfectant loss begins when the product of disinfectant decay constant and the refill time for an empty tank exceeds 0.1, and that disinfectant residuals are relatively insensitive to the fraction of total volume devoted to emergency storage. A second, numerical solution to the model is developed to account for the fact that tank fill and drain rates are constrained by system demand patterns, pump capacity, and pump scheduling. Results show that pulsed or periodic pumping during a portion of the day can maintain much higher disinfectant residuals than continuous pumping can. However, such pumping policies require additional pump capacity and operating storage volume.

Safety design and radioactive-waste-disposal analysis for the TITAN-II reversed-field-pinch reactor design

Abstract Strong emphasis was given to safety engineering in the TITAN study. Instead of an add-on safety design and analysis task, the safety activity was incorporated into the process of design selection and integration at the beginning of the study. Low afterheat structural material, V3 Ti1 Si was used. Passive safety features like Ar cover gas, lithium drain tanks were used to minimize the likelihood and consequence of lithium fire. Plasma accident scenarios were evaluated and found that passive safety features can be incorporated into the design. Detailed safety analysis indicated that only the assurance of coolant-piping and vacuum-vessel integrity is necessary to protect the public. The TITAN-I design meets the definition of level 3 of safety assurance design “small-scale passive safety assurance”.

Safety design and radioactive-waste-disposal analysis for the TITAN-1 reversed-field-pinch reactor design

Strong emphasis was given to safety engineering in the TITAN study. Instead of an add-on safety design and analysis task, the safety activity was incorporated into the process of design selection and integration at the beginning of the study. Low afterheat structural material, V3 Ti1 Si was used. Passive safety features like Ar cover gas, lithium drain tanks were used to minimize the likelihood and consequence of lithium fire. Plasma accident scenarios were evaluated and found that passive safety features can be incorporated into the design. Detailed safety analysis indicated that only the assurance of coolant-piping and vacuum-vessel integrity is necessary to protect the public. The TITAN-I design meets the definition of level 3 of safety assurance design “small-scale passive safety assurance”.

Chamaecyparis thyoides Wetlands and Suburbanization: Effects on Hydrology, Water Quality and Plant Community Composition

(1) Atlantic white cedar (Chamaecyparis thyoides) wetlands in the New Jersey Pinelands were studied along a gradient of suburban development defined by increasingly intrusive road and house construction close to the site. Water table level, water chemistry, plant species composition and community structure were recorded to assess the effects of increasing levels of upland disturbance on the adjacent wetlands. (2) Some increases in nitrogen, phosphorus, and chloride occurred in both surface and groundwater within wetlands beside septic system drain fields. Much larger increases in these parameters, plus increases in heavy metal concentrations, occurred in sites receiving both septic tank drainage and road run-off. (3) Hydrology was only affected by the presence of dams on the streams traversing the wetlands, and by ditches dug in association with stormwater sewer outfalls. (4) With increasing levels of suburban disturbance, there was an increasing loss of indigenous herbaceous species and an increasing incursion of upland and exotic species. Ground cover by Sphagnum spp. and cedar seedling densities all declined with increasing suburban development. Woody plant community composition and structure showed little change over the gradient. Changes in water quality were more important in determining changes in community composition and structure than were changes in hydrology. (5) The changes in species composition associated with changes in water quality support the theory that species-richness follows an optimization curve with respect to nutritional quality of the wetland. (6) The results suggest that the maximum buffer width provided for by law be required for all upland development adjacent to white cedar wetlands.

The yield stress of frozen hydrocarbon fuels

A more complete description of the flow properties of frozen hydrocarbon fuels is necessary to deal with practical problems such as tank drainage and line stoppage. A study has been made of the minimum stress necessary to effect a change in frozen fuels and hydrocarbon mixtures from solid-like to liquid-like behaviour, by measuring the torque required to rotate an immersed vaned rotor. Experimental variables that affect the interpretation of the results as a rheologically defined yield stress were explored. The yield stress was highly dependent on the temperature and the n-alkane composition of the sample. The total n-alkane concentration determined the rate of increase in yield stress with temperature decrease. For a given total n-alkane concentration, the temperature at which a given yield stress was reached increased with the average n-alkane carbon chain length. While yield stress of frozen hydrocarbons is primarily dependent on the total solids present, other mechanisms involving crystal interactions appear to be necessary for interpretation of the results. Information about yield stress of a frozen fuel as a function of temperature provides a precise, rheologically sound basis for formulating improved methods of forecasting field performance.

The safety designs for the TITAN reversed-field pinch reactor study

TITAN is a study to investigate the potential of the reversed-field pinch concept as a compact, high-power density energy system. Two reactor concepts were developed, a self-cooled lithium design with vanadium structure and an aqueous solution loop-in-pool design, both operating at 18 MW/m 2 . The key safety features of the TITAN-I lithium-vanadium blanket design are in material selection, fusion power core configuration selection, lithium piping connections, and passive lithium drain tank system. Based on these safety features and results from accident evaluation, TITAN-I can at least be rated at a level 3 of safety assurance. For the TITAN-II aqueous loop-in-pool design, the key passive feature is the complete submersion of the fusion power core and the corresponding primary coolant loop system into a pool of low temperature water. Based on this key safety design feature, the TITAN-II design can be rated at a level 2 of safety assurance.

Studies of Power Station Feed Pump Loss of Suction Pressure Incidents

Open cycle feed systems featuring a deaerator followed by the boiler feed pumps have been subject to unexpected loss in net positive suction head during transient operation. This has been traced to separation at the deaerator storage tank drain and the formation of a steam/water interface in the downcomer to the pumps. The outflow at separation when the storage tank water is subcooled is generally much greater than the maximum suction flow corresponding to the unit rating, but when the tank water boils, as during transients, it may be very much less. Thus with a high suction flow in the boiling mode, the new interface may descend in the downcomer to result in feed pump cavitation, pressure imbalance, vapor locking, severe vibration, damage to the pump and an inability to maintain forward flow. Model tests have been conducted to establish the criterion for the separation in terms of the critical outflow for specific operating conditions as a function of geometric ratios involving tank-water depth and tank/downcomer dimensions. The data obtained although scattered are in general agreement with the data from actual plant and may be used to assess safe operating parameters.

Test method for evaluation of loss of prime in metered-dose aerosols

A new test method is described for assessing the loss of prime in metered-dose aerosols. Two representative metered-dose valve designs and two storage positions were used to assess the utility of this test method at three different sites. Loss of prime, defined as a valve delivery 15% below the mean, was detected in three of the four test configurations. The first significant loss of prime in this study was observed at the two-week time point for valves without drain tanks stored in the upright position. Onset of loss of prime was shown to be dependent on valve design as well as storage position, thus alternate valves or storage conditions should yield different results. This test method appeared to be reproducible over the three test sites, with a slight variation in results attributed to differences in storage conditions and agitation during sample handling. This test method intentionally excluded agitation which is in sharp contrast to the normal “shake well before use” instruction to the patient. Following one priming actuation, all of the valves returned to their mean valve delivery.

Retran Analysis of Susquehanna Steam Electric Station Unit 2 Moisture Separator Drain Tank Level Transient Response

Susquehanna Steam Electric Station Unit 2 (SSES-2) experienced three main turbine trips on high moisture separator drain tank level during initial startup testing in 1984. The SSES-2, a 3293-MW(thermal) boiling water reactor-4 with Mark II containment, uses two parallel nonreheating moisture separators between the high- and low-pressure turbine stages. Two of the main turbine trips and subsequent scrams occurred due to the high level in the “B” moisture separator drain tank during combined intermediate valve testing. The third trip was also initiated on the same signal, but during a recirculation pump run-back event.A task group was created to determine the cause of the level excursions and to make recommendations to reduce the severity of these transients. The RETRAN-02 computer code was used to evaluate the dynamic response of both the A and B moisture separator drain systems to determine the cause of the events, including why the level excursions only occurred in the B system. RETRAN was also used to evaluate the systems’ dynamic response to several proposed corrective plant modifications.Based on the recommendations of the task group, modifications were made to SSES-2 during the precommercial operation outage. Startup testing following the outage proved the success of the modifications.

Method of Land Reclamation by Application of the Quaternary Research

Volcanic ash soils show peculiar engineering properties owing to their abundant moisture contents. So there are many problems in connection with land reclamation of these soils. Engineering properties of these soils were examined with emphasis on the phenomenon of softening and hardening.The following results were obtained.(1) The dry density of compaction soil samples were effected more by soil genesis and moisture contents than by external force. Younger tephra (Tachikawa Loam Formation) showed a low degree of dry density.(2) The degree of softening and hardening depended on the age of tephra. Younger tephras (post-Tachikawa Loam, Tachikawa Loam and Musashino Loam Formations) showed low degrees of softening with much recovery of strength.(3) The same tephra, containing much moisture, softened to a large degree, with less hardening. With little moisture, the degree of softening was low with more hardening. This phenomenon could be explained by the relation between soil moisture and structure.(4) At the soil fill, the permeability fell by compaction. So it is necessary to set up surface and subsurface drainage, pipe drain and sedimentation tank.(5) Volcanic ash soils with humic materials are not suitable for construction from the viewpoints of strength and permeability, but for the green tract of land.

Investigations of pipe-borne pollution in Benin City, Nigeria

Two important environmental parameters could be identified as being the main causes of pipe borne water contamination in the City of Benin. These are the combined effects of rainfall and excessive construction work and, secondly, the lack or inadequacy of plumbing codes. To study the combined effects of rainfall and excessive construction on the contamination of water, samples were tested for total coliform using the multiple-tube fermentation test. Sites were chosen to allow for the comparison of the coliform counts in areas of comparatively insignificant construction to areas of excessive public construction. Results show that in the areas of heavy public construction, the curves for both the rainfall and the coliform counts in the consumer lines were skewed in the same manner. The peak rainfall was in September (437.I mm) which corresponds to peak coliform number in the consumer lines for both Zone A (62 coliforms/100 ml) and Zone B (60 coliforms/100 ml) for the same month. When compared to the area of insignificant public construction as shown in Zone C, rainfall had little or no effect on the coliform counts either at the pumping station or in the consumer line. The maximum number of coliforms recorded for the consumer line was 5/100 ml during the month of June. Results suggest that the high counts of coliforms in the Benin City water supply could be attributed primarily to the effects of construction which resulted in pipe breakage. During heavy rainfall and flooding, water under flood pressure enters the pipes through cracks, improperly tightened joints and damaged pipes. The improper enforcement of plumbing codes or lack of such codes was also identified as another cause of the water contamination as shown in Zone D. A study of the effects of water pipes passing through septic tank drain fields also shows that such effluents served as another source of major contamination. The highest recorded number for coliforms for the pipe-borne water just before entering the septic tank drain field was 12/100 ml and after it passed through the field the number had gone up to 60/100 ml. Artificial contamination of the septic tank effluents to try to detect leaks in the water pipes passing through the absorption field was investigated. The bacterial contaminant could be recovered in the pipe-borne water and the quantity was skewed in the same manner as total rainfall between periods of sampling.

Computer calculations of air and steam blowdown suppression

We describe a computer code that combines an Eulerian incompressible-fluid algorithm (SOLA) with a Lagrangian finite-element shell algorithm. The former models the fluid and the latter models the containing structure in an analysis of pressure suppression in boiling-water reactors. The code (PELE-IC) calculates loads and structural response from air blowdown and from the oscillatory condensation of steam bubbles in a water pool. The fluid, structure, and coupling algorithms are tested by recalculating problems that have known analytical solutions, including tank drainage, spherical bubble growth, coupling for circular plates, and submerged cylinder vibration. Code calculations are also compared with the results of small-scale blowdown experiments.

The role of food particle size in the growth of juvenile Atlantic salmon (Salmo salar L.)

The effect of particle size of a commercial pelleted feed on the growth of Atlantic salmon from first feeding alevins to first and second year smolts was investigated using 20‐day feeding experiments. Ten experiments were performed over a two year period, each comprising six groups of fish separately selected from stock populations. Each group was presented with one of six sizes of food particle ranging from larger than the respective mean mouth breadth (100% feed size), through 50%, 25%, 12·5%, 6·25% to 3·125%. Experiments were performed in six radial flow/circumferential drain tanks under ambient photoperiod and water temperature. Growth rate was found to be closely related to feed size. Maximum growth in each case was shown only on one size of particle; larger and smaller sizes resulted in reduced growth. The particle size for maximum growth increased in direct proportion to fish length. Fish from 4·2 to 20·3 cm in length showed maximum growth on particle diameters 0·022 to 0·026 × fish fork length (PFR). First feeding alevins were found to show comparable growth rate on particle diameters 0·0115 to 0·090 PFR. Some seasonal variation in growth response was indicated. The results are discussed in relation to developmental and seasonal effects. Possible factors affecting the energetics of prey size related differential growth are discussed.

Influence of Artificial Drainage on Penetration of Coliform Bacteria from Septic Tank Effluents into Wet Tile Drained Soils

AbstractThe penetration of total and fecal coliform bacteria from septic tank drainage fields into wet tile drained soils classified as Typic and Aeric Ochraquults was studied during 1974, 1975, and 1976. These bacteria were monitored in ground waters at selected distances from the septic tank drainage fields in the direction of ground water flow and were compared to coliform densities in control wells and in tile outfalls. Fecal coliform densities were approximately 105/100 ml in ground waters adjacent to the disposal area as compared to 101–103/100 ml 152 cm from the agricultural tile and &lt;3.0/100 ml in control wells. The outfall from the study area was normally &lt; 200 fecals/100 ml compared to &lt; 3.0/100 ml in outfall waters from a control area. Fecal coliform densities of the outfall from the study area were some tenfold less than the bacterial quality of the receiving stream. Coliform densities in ground waters decreased as a logarithmic function of distance.In these soils, artificial drainage systems apparently lowered the seasonal fluctuating water tables to such a degree that individual waste water treatment systems did not fail as a result of untreated or partially treated effluent coming to the surface. It is more difficult to access the adequacy of artificial drainage with respect to penetration of coliform organisms present in the waste waters.

Heater drain deaeration in BWR nuclear station under pumped forward conditions

Abstract Water chemistry conditions in BWR nuclear stations are presented. Based on the available BWR operational data, a predictable oxygen concentration of as much as 1500 ppb in the low-pressure feedwater drains being pumped forward was determined. The BWR feedwater oxygen content criteria can be met at all operating modes if the heater drain tank is equipped with a deaerating device such as the steam bubbling type indicated and described in this paper.

Potential Replacement of Septic Tank Drain Fields by Artificial Marsh Wastewater Treatment Systemsa

ABSTRACTIndividual subsurface liquid waste disposal has been cited as a source of ground‐water contamination. Wastewater treatment systems using emergent marsh vegetation planted in a gravel substrate in a plastic‐lined trench could be used to treat septic tank effluent. A pilot plant treating unchlorinated primary municipal effluent achieved the following reductions in mass: BOD5‐77%; COD‐71%; orthophosphate–35%; total phosphorus–37%; nitrate–22%; coliform bacteria–99.9%. While such treatment is possible only during the growing season, it could be useful at summer cottages, camping areas, resorts and roadside rest areas. Marsh treatment systems are inexpensive to operate and virtually automatic.