Vessel Score Research Articles

Interpretation of Conductivity-Sensitive Liquid-Level Transducer Signals in a Small Break Loss-of-Coolant Accident Test Facility

Numerous issues regarding nuclear plant safety have stimulated experimental and computational efforts associated with the thermal hydraulics of reactor cooling systems. A scaled test facility of the Babcock & Wilcox raised-loop nuclear steam supply system was used to perform small break loss-of-coolant accident testing, thereby establishing a data base from which plant predictive system codes could be benchmarked. About 250 instruments were used to record the thermal-hydraulic response of the test facility during the transient, of which 36 were conductivity probes. These probes were designed and installed to determine the liquid/steam interface in the facility hot leg, reactor core vessel, and steam generator components. This study presents the data interpretation of the conductivity probe output signals for various tests. It is concluded that the “dry” state (steam) exists when the conductivity probe output voltage falls to the zero value of ∼0.05 V, independent of the fluid vapor temperature in which the probe is immersed. The temperature variations may significantly alter the probe output signal when immersed in single-phase water or a two-phase steam and water mixture, due to the change in electrical conductivity of the water with temperature.

Cerebral atherosclerosis in European populations: a preliminary report.

Atherosclerosis in the arteries of the circle of Willis was studied in European populations using a coding technique developed by Baker and his associates. Results from six countries (Finland, Germany, Greece, Norway, Italy, and Poland) were compared with results from Minnesota. The material from the first four countries was coded by the Minnesota team, whereas the material from Italy and Poland was coded by their respective investigators. The frequency of cerebral atherosclerosis was highest in the German and Finnish populations and was lowest in the Polish population. The Norwegian, Greek and Italian populations showed frequencies of cerebral atherosclerosis quite similer to those in the Minnesota material. The average amount of cerebral atherosclerosis was established by determining the median vessel scores by ten-year age groups for the material coded by the Minnesota team. The Finnish population had the highest average involvement; the Finnish, German, and Greek populations all showed higher average vessel scores for cerebral atherosclerosis than the Minnesota population.

High Sensitive C-Reactive Protein (hs-CRP) and Its Correlation with Angiographic Severity of Patient with Coronary Artery Disease (CAD)

Background: Association between the plasma hs-CRP levels and the severity of coronary stenosis in subjects remains controversial. This cross sectional study was performed in the Department of Cardiology, Dhaka Medical College during July 2008 to December 2009, to determine whether the concentrations of hs-CRP correlate with the coronary atherosclerotic disease assessed by coronary angiography. Methods: For this purpose, a total number of 90 consecutive patients having IHD admitted in the Dhaka Medical College Hospitals were enrolled in this study. Patients were divided into three groups according to their level of hs-CRP. Out of 90 cases, 22(24.4%) patients were in group I, in group II 33(36.7%) patients and rest 35(38.9%) were in group III according to their hs-CRP level. Severity of CAD was assessed by vessel score, stenosis score and extent score. Result: Significant positive correlation (r=0.7409; p<0.001 r=0.6648; p<0.001 and r=0.6386; p<0.001) was found between hs-CRP and vessel score, stenosis score and hs-CRP and extent score suggesting increasing level of hs-CRP strongly suggestive of extensive coronary artery disease. Conclusion: High level of hs-CRP strongly suggestive of extensive coronary artery disease Key words: hs-CRP; angiogram; coronary artery disease; vessel score; stenosis score and extent score. DOI: 10.3329/jdmc.v19i2.7076J Dhaka Med Coll. 2010; 19(2) : 91-97

Risk Factors Analysis and Angiographic Profile in Postmenopausal Women with Coronary Artery Disease

Background : Postmenopausal women are at greater risk for coronary artery disease (CAD) than premenopausal women. This may be due to deprivation of estrogen, which acts directly and indirectly on the vasculature. In light of this finding the aim of the study was to find the relation of serum estrogen level with severity of atherosclerotic lesion and number of risk factors in CAD among postmenopausal women. Methods: One hundred postmenopausal women undergoing coronary angiography (CAG) were studied. Among them 50 patients with estrogen level <25 pg/ml constituted study Group I and another 50 postmenopausal women with >25 pg/ml constituted study Group II. Serum estrogen level was measured by radioimmunoassay. Other important risk factors like dyslipidaemia, diabetes mellitus, hypertension, family history of CAD, smoking and waist circumference were evaluated between the 2 groups of patients. CAG findings were analyzed by eye estimation and by Gensini score. Results: All the risk factors were significantly higher in Group I patients than that of Group II. Among the risk factors hypertension was most prevalent (64%) in Group I and dyslipidaemia (40%) in Group II. Multivariate regression analysis showed that serum estrogen was a strong and an independent predictor of CAD (p=0.001) when considered with other standard risk factors. Association between the angiographic severity of CAD and serum estrogen level were evaluated and negative correlation was observed, i.e. lower the serum estrogen level higher the vessel score. Conclusion: In postmenopausal women serum estrogen level is a strong & an independent predictor of CAD. It is also found that low estrogen group of postmenopausal women with CAD have more severe atherosclerotic lesions in comparison to the group with normal estrogen level. Keywords: Risk factor, Coronary artery disease, Postmenopausal women, Angiographic profile. DOI: http://dx.doi.org/10.3329/cardio.v1i2.8235 Cardiovasc. j. 2009; 1(2): 161-164

Measurement of the fission recoil separation effect in an aqueous fuel suspension using a homogeneous subcritical reactor assembly

The fission recoil separation effect has been measured by determination of the distribution of iodine, yttrium and rare earths over the solid and the liquid of an aqueous fuel suspension. The separation effect depended on both the colloid chemical condition of the suspension and the hydrodynamical conditions in the core vessel. In one particular case agreement was found between the experimental results and calculations based on the particle size distribution. Disagreement in another case could be explained by local increases of concentration caused either by flocculation or the flow pattern in the vessel.

Experiments with a subcritical reactor, in which an aqueous suspension of UO 2 particles is circulating

Measurements on source multiplication and on neutron flux variations (reactor noise) have been used to investigate rheological and reactor physical properties of an aqueous homogeneous subcritical reactor, in which a suspension of UO 2 particles is circulating at room temperature. It has been shown that both the colloid chemical properties of the suspension and the hydrodynamical conditions inside the core vessel have a strong influence on the behaviour of the reactor at steady operation. Interesting results have also been obtained under abnormal operating conditions. The effective delayed neutron fraction has been measured as a function of the circulating velocity and the result appeared to be in agreement with theoretical considerations.

Thermal Stresses in Nuclear Reactor Vessel Nozzles

A major design problem in reactors which use a heavy-walled core vessel is the study of the thermal shock imposed on this vessel by rapid temperature changes in the inlet temperature of the coolant. The thermal stress analysis of the nozzles of a large, heavy-walled, clad reactor vessel is dfscussed. Two cases are considered' decay heat removal after shutdown and small temperature differences at high flow rates and short times during normal operatfon. (W.D.M.)

AEC Safety Research Program — Reactor Design Factors

The research falls into three loglcal categories: reactor kinetics and control, potential chemlcal reactions, and reactor containment. The first category lncludes lnherent nuclear characterlstics that mlght cause reactor runaway or shutdown. Thc second category lncludes such reactions as molten metal- water, metal-gas, and flsslon product release from fuel elements. The third lncludes both reactor core vessel and reactor conthlnment shell lntegrity. (D.F.B.)