Design of a supercritical water-cooled reactor with a three-pass core arrangement

The Supercritical Water-cooled Reactor (SCWR) is one of the six concepts of the Generation IV International Forum. In Europe, investigations have been integrated into a joint research project, called High Performance Light Water Reactor (HPLWR). Due to the higher heat up within the core and a higher outlet temperature, a significant increase in turbine power and thermal efficiency of the plant can be expected.Besides the higher pressure and higher steam temperature, the design concept of this type of reactor differs significantly from a conventional LWR by a different core concept. In order to achieve the high outlet temperature of over 500 °C, a core with a three-step heat up and intermediate mixing is proposed to keep local cladding temperatures within today's material limits. A design for the reactor pressure vessel (RPV) and the internals has been worked out to incorporate a core arrangement with three passes. All components have been dimensioned following the safety standards of the nuclear safety standards commission in Germany. Additionally, a fuel assembly cluster with head and foot piece has been developed to facilitate the complex flow path for the multi-pass concept. The design of the internals and of the RPV is verified using mechanical or, in the case of large thermal deformations, combined mechanical and thermal stress analyses. Furthermore, the reactor design ensures that the total coolant flow path remains closed against leakage of colder moderator water even in case of large thermal expansions of the components. The design of the RPV and internals is now available for detailed analyses of the core and the reactor.     

High performance light water reactor

The objective of the high performance light water reactor (HPLWR) project is to assess the merit and economic feasibility of a high efficiency LWR operating at thermodynamically supercritical regime. An efficiency of approximately 44% is expected. To accomplish this objective, a highly qualified team of European research institutes and industrial partners together with the University of Tokyo is assessing the major issues pertaining to a new reactor concept, under the co-sponsorship of the European Commission. The assessment has emphasized the recent advancement achieved in this area by Japan. Additionally, it accounts for advanced European reactor design requirements, recent improvements, practical design aspects, availability of plant components and the availability of high temperature materials. The final objective of this project is to reach a conclusion on the potential of the HPLWR to help sustain the nuclear option, by supplying competitively priced electricity, as well as to continue the nuclear competence in LWR technology. The following is a brief summary of the main project achievements:

• A state-of-the-art review of supercritical water-cooled reactors has been performed for the HPLWR project.

• Extensive studies have been performed in the last 10 years by the University of Tokyo. Therefore, a ‘reference design’, developed by the University of Tokyo, was selected in order to assess the available technological tools (i.e. computer codes, analyses, advanced materials, water chemistry, etc.). Design data and results of the analysis were supplied by the University of Tokyo. A benchmark problem, based on the ‘reference design’ was defined for neutronics calculations and several partners of the HPLWR project carried out independent analyses. The results of these analyses, which in addition help to ‘calibrate’ the codes, have guided the assessment of the core and the design of an improved HPLWR fuel assembly.

• Preliminary selection was made for the HPLWR scale, boundary conditions, core and fuel assembly design, reactor pressure vessel, containment, turbine and balance of plant.

• A review of potentially applicable materials for the HPLWR was completed and a preliminary selection of potential in-vessel and ex-vessel candidate materials was made.

• A thorough review of heat transfer at supercritical pressures was completed together with a thermal-hydraulics analysis of potential HPLWR sub-channels. This analytical tool supports the core and fuel assembly design.

• The RELAP5 and the CATHARE 2 codes are being upgraded to supercritical pressures. Thus they can be used to support the HPLWR core design and to perform plant safety analyses.

• Assessment of the HPLWR design constraints, based on current LWR technology was documented. This document stresses the various criteria that must be satisfied in the design (e.g. material, temperature, power, safety criteria, etc.) based on experience gained in the design of PWR.

• Preliminary economic assessment concluded that the HPLWR has the potential to be economically competitive. However, an accurate assessment can only be done after the HPLWR design has been fixed. A more accurate economic assessment may be performed after the conclusion of this project.

Preventing alcohol misuse: The impact of refusal skills and norms.

The purpose of this study was to determine the extent to which refusal skills and norm setting mediated the impact of a school-based prevention program from the Alcohol Misuse Prevention Study (AMPS) on adolescent alcohol overindulgence. The AMPS is a randomized, pre-post, experimental-control study. Respondents in the present study included 6th through 10th graders (ns ranged from 232 to 371). Structural equation modeling analyses using EQS indicated that norm setting mediated the effect of the intervention on alcohol overindulgence at the 7th through the 8th grade and at the 8th through the 10th grade. In contrast, although the prevention program served to increase refusal skills, refusal skills did not mediate the effect of the program on alcohol misuse. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Computer Aversion, Attitudes, and Familiarity Index (CAAFI): A validity study

This study’s purpose was to provide additional psychometric data on the Computer Aversion, Attitudes, and Familiarity Index (CAAFI). The CAAFI is comprised of 40 items, yielding a total score and four factor scores with 10 items each (one familiarity, one attitudes, two aversion). The measure was administered to a sample of undergraduate psychology students (N = 293) along with the Computer Understanding and Experience Scale, the Computer Attitude Scale, and the Computer Aversion Scale. The factor structure of the CAAFI was supported via confirmatory factor analytic procedures and analysis of internal consistency reliability coefficients. In relation to the other measures of computer-related constructs, the strongest validity support was found for the CAAFI total score and Factors 1 (computer familiarity) and 3 (computer aversion-discomfort), followed by Factor 2 (computer attitudes). With regard to Factor 4 (computer aversion-fear), given the results of the analyses the decision was made to remove these items from the CAAFI in order to enhance the measure’s psychometric properties and practical utility.     

How part-time work intensity relates to drug use, problem behavior, time use, and satisfaction among high school seniors: Are these consequences or merely correlates?

Related work intensity (hours worked per week) to indicators of psychosocial functioning and adjustment by using nationally representative samples of high school seniors, totalling over 70,000 respondents, from the classes of 1985–1989. Consistent with previous research, bivariate correlations were positive between work intensity and problem behaviors; these associations were diminished (but not eliminated) once background and educational success indicators were controlled, thus suggesting that selection factors contribute to the correlations. Work intensity appears to reduce the likelihood of getting sufficient sleep, eating breakfast, exercising, and having a satisfactory amount of leisure time. Conceptual and policy implications are discussed, including the possibility that long hours of part-time work may be both a symptom and a facilitator of psychosocial difficulties. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Twelfth-grade student work intensity linked to later educational attainment and substance use: New longitudinal evidence.

Long hours of paid employment during high school have been linked to a variety of problem behaviors, but questions remain about whether and to what extent work intensity makes any causal contribution. This study addresses those questions by focusing on how 12th-grade work intensity is associated with substance use and educational attainment in the years following high school. It uses 2 nationally representative longitudinal data sets from the Monitoring the Future project, spanning a total of 3 decades. One data set tracks 8th graders for 8 years (modal ages 14–22) and provides extensive controls for possible prior causes; the second, larger data set tracks 12th graders for up to 12 years (to modal ages 29–30) and permits assessment of possible short-term and longer term consequences. Findings based on propensity score matching and multivariate regression analyses are highly consistent across the 2 sets of data. All findings show that more fundamental prior problems, including low academic performance and aspirations, make substantial contributions to substance use and long-term academic attainment (selection effects), but the findings also suggest that high work intensity during high school has long-term costs in terms of college completion and perhaps cigarette use. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

How trajectories of reasons for alcohol use relate to trajectories of binge drinking: National panel data spanning late adolescence to early adulthood.

Developmental changes in both alcohol use behaviors and self-reported reasons for alcohol use were investigated. Participants were surveyed every 2 years from ages 18 to 30 as part of the Monitoring the Future national study (analytic weighted sample size N = 9,308; 53% women, 40% college attenders). Latent growth models were used to examine correlations between trajectories of binge drinking and trajectories of self-reported reasons for alcohol use across young adulthood. Results revealed developmental changes in reasons for use and correlations between the patterns of within-person change in frequency of binge drinking and within-person change in reasons for use. In particular, an increase in binge drinking between ages 18 and 22 was most positively correlated with slopes of using alcohol to get high and because of boredom. Continued binge drinking between ages 22 and 30 was most strongly correlated with using alcohol to get away from problems. Almost no moderation by gender, race, college attendance, employment, or marital status was found. Binge drinking and reasons for alcohol use traveled together, illustrating the ongoing and dynamic connections between changes in binge drinking and changes in reasons for use across late adolescence and early adulthood. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Husbands' and wives' alcohol use disorders and marital interactions as longitudinal predictors of marital adjustment.

In this longitudinal study, the relationships among wives' and husbands' lifetime alcoholism status, marital behaviors, and marital adjustment were tested. Participants were 105 couples from the Michigan Longitudinal Study (MLS), an ongoing multimethod investigation of substance use in a community-based sample of alcoholics, nonalcoholics, and their families. At baseline (T1), husbands and wives completed a series of diagnostic measures, and lifetime diagnosis of alcohol use disorder (AUD, as defined in the Diagnostic and Statistical Manual of Mental Disorders, 4th ed.), was assessed. Couples completed a problem-solving marital interaction task 3 years later at T2, which was coded for the ratio of positive to negative behaviors. Couples also completed a measure of marital adjustment at T4 (9 years after T1 and 6 years after T2). Results showed that husbands' lifetime AUD predicted lower levels of their wife's positive marital behaviors 3 years later but was not related to their own or their wife's marital adjustment 9 years from baseline. By contrast, wives' lifetime AUD had direct negative associations with their own and their husband's marital satisfaction 9 years later, and wives' marital behaviors during the problem-solving task predicted their own and their husband's marital satisfaction 6 years later. Findings indicate that marital adjustment in alcoholic couples may be driven more by the wives' than the husbands' AUD and marital behavior. Implications for intervention with alcoholic couples were discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Supercritical water heat transfer in vertical tubes: A look-up table

A new procedure for the prediction of wall temperatures in vertical tubes has been established in the framework of the development of the High Performance Light Water Reactor (HPLWR). The prediction of the wall temperature is accomplished by a look-up table for heat transfer in supercritical water. The look-up table lists the wall temperatures as a function of mass flux, heat flux, pressure, tube diameter, and bulk enthalpy. Based on an extended literature survey, experimental data for different conditions of upward flows in vertical smooth tubes are selected. To exclude data which exhibited local, buoyancy driven effects, a criterion of Jackson for deterioration of heat transfer is used to remove these data from further processing. An interpolation method is applied to assemble the tabulated grid points, based on published correlations for heat transfer in supercritical water. The look-up table covers a mass flux range of 700–3500 kg/m² s, a heat flux range of 300–1600 kW/m², a pressure range of 22.5–25 MPa, a diameter range of 8–20 mm and a bulk enthalpy range of 1200–2700 kJ/kg. Extreme combinations which required extrapolation of the data are excluded. The accuracy of the table in the vicinity of the pseudo-critical point is significantly higher than published correlations.