CONCENTRATION OF SETTLED BEDS OF THORIA SLURRY

The variation in concentration of settled beds of flocculated aqueous suspensions of thoria was studied experimentally as a function of the calcination temperature and particle size of the thoria, the temperature and initial concentration of the suspension, and the concentration of added chromic acid. Values of the ultimate settled-bed concentration were obtained by several methods. Dilatant-plastic behavior of one suspension was considered responsible for the formation, in long vertical tubes, of intractable plugs. (auth

Association between initial use of e-cigarettes and subsequent cigarette smoking among adolescents and young adults a systematic review and meta-analysis

IMPORTANCE The public health implications of e-cigarettes depend, in part, on whether e-cigarette use affects the risk of cigarette smoking. OBJECTIVE To perform a systematic review and meta-analysis of longitudinal studies that assessed initial use of e-cigarettes and subsequent cigarette smoking. DATA SOURCES PubMed, EMBASE, Cochrane Library,Web of Science, the 2016 Society for Research on Nicotine and Tobacco 22nd Annual Meeting abstracts, the 2016 Society of Behavioral Medicine 37th Annual Meeting & Scientific Sessions abstracts, and the 2016 National Institutes of Health Tobacco Regulatory Science Program Conference were searched between February 7 and February 17, 2017. The search included indexed terms and text words to capture concepts associated with e-cigarettes and traditional cigarettes in articles published from database inception to the date of the search. STUDY SELECTION Longitudinal studies reporting odds ratios for cigarette smoking initiation associated with ever use of e-cigarettes or past 30-day cigarette smoking associated with past 30-day e-cigarette use. Searches yielded 6959 unique studies, of which 9met inclusion criteria (comprising 17 389 adolescents and young adults). DATA EXTRACTION AND SYNTHESIS Study quality and risk of biaswere assessed using the Newcastle-Ottawa Scale and the Risk of Bias in Non-randomized Studies of Interventions tool, respectively. Data and estimates were pooled using random-effects meta-analysis. MAIN OUTCOMES AND MEASURES Among baseline never cigarette smokers, cigarette smoking initiation between baseline and follow-up. Among baseline non-past 30-day cigarette smokers who were past 30-day e-cigarette users, past 30-day cigarette smoking at follow-up. RESULTS Among 17 389 adolescents and young adults, the ages ranged between 14 and 30 years at baseline, and 56.0%were female. The pooled probabilities of cigarette smoking initiationwere 30.4%for baseline ever e-cigarette users and 7.9%for baseline never e-cigarette users. The pooled probabilities of past 30-day cigarette smoking at follow-upwere 21.5%for baseline past 30-day e-cigarette users and 4.6%for baseline non-past 30-day e-cigarette users. Adjusting for knowndemographic, psychosocial, and behavioral risk factors for cigarette smoking, the pooled odds ratio for subsequent cigarette smoking initiationwas 3.62 (95%CI, 2.42-5.41) for ever vs never e-cigarette users, and the pooled odds ratio for past 30-day cigarette smoking at follow-up was 4.28 (95%CI, 2.52-7.27) for past 30-day e-cigarette vs non-past 30-day e-cigarette users at baseline.Amoderate level of heterogeneitywas observed among studies (I2 = 60.1%). CONCLUSIONS AND RELEVANCE e-Cigarette use was associated with greater risk for subsequent cigarette smoking initiation and past 30-day cigarette smoking. Strong e-cigarette regulation could potentially curb use among youth and possibly limit the future population-level burden of cigarette smoking

Status of motor operated valves aging assessment

Motor operated valves (MOVs) have a long history of operational problems in nuclear power plants. Resolution of MOV problems in the past has tended to focus on symptoms rather than root cause. Although there has been more attention focused recently on identifying root causes, problems with valve operational readiness resulting from aging and service wear still persist. In addition, weaknesses in the currently used design equations for sizing of MOVs, identified in tests carried out by industry and confirmed in the recent NRC gate valve blowdown testing, have re-enforced the need for improved in-situ methods for determining the operational readiness of MOVs, whether from aging and service wear or from improper installation and maintenance. The objective of the MOV aging assessment is to evaluate and recommend practical methods for insuring operational readiness of safety-related MOVs under all anticipated operating conditions

Aging and defect characterization of motor-operated valves: progress based on NPAR strategy. [PWR; BWR]

The Nuclear Plant Aging Research (NPAR) program strategy is directed at carrying out comprehensive aging assessments in order to define and resolve issues related to aging (including service wear) of electrical and mechanical components and structures at operating reactor facilities and their possible impact on plant safety. This paper describes work recently completed at Oak Ridge National Laboratory which applied the NPAR strategy to motor-operated valves (MOVs). The objective of the work was primarily to develop an understanding of the operating history and conditions and the failure modes of MOVs in nuclear plant service as a preliminary to identifying and recommending methods for trending aging degradation. A second objective was to demonstrate, using MOVs as an example, that the NPAR strategy can be applied to many electrical and mechanical components of nuclear power plants

RELATIONSHIP BETWEEN CALCINING TEMPERATURE AND PARTICLE DENSITY OF THORIA SLURRIES

The variation in rheologlcal behavior and other physical properties of thoria slurries with the calcining temperature of the thoria powder is explained on the basis of the relation between the calcining temperature and the bulk density of the individual thoria particles. Indirect experimental measurements of the bulk particle density by viscosimetry and by measurement of centrifuged- bed denslties agreed wlth each other and fell within the predicted density limlts of 3.7 g/cc and 9.7 g/cc (for oxalateprecipitated thoria). Nitrogen adsorption porosimetry of one sample was consistent with the bulk-density measurement. (auth

Application of diagnostics to determine motor-operated valve operational readiness

ORNL has been carrying out an aging assessment of motor-operated valves (MOVs) with the primary objective of recommending diagnostic methods for detecting and trending aging. As a result of experimental investigations at ORNL, it was discovered that the motor current during a valve stroke was a very useful diagnostic parameter for detecting and trending many MOV drive train load variations. The motor curent signatures were analyzed at four levels: mean value for a stroke, gross trends during a stroke, transients, and noise frequency spectra. Examples illustrating the use of this technique are presented. The use of motor current signature analysis was also shown to apply to other electric motor driven equipment. Future work includes developing a data base of MOV diagnostics, including criteria for determining the extent of degradation and application of the technique to other LWR motor driven safety equipment

Low-temperature thermal energy storage program annual operating plan

The Low-Temperature Thermal Energy Storage (LTTES) Program operating plans for FY 1979 are described in terms of general program objectives and the technical activities being implemented to achieve these objectives. The program structure provides emphasis on several principal thrusts; namely, seasonal thermal storage, daily/short-term thermal storage, and recovery and reuse of waste heat. Fiscal data are summarized according to thrust area, individual efforts, and funding source

Evaporative heat transfer in vertical tubes at geothermal brine conditions: a preliminary investigation

Overall heat-transfer coefficients were obtained in a single-tube loop for a smooth tube and two fluted tubes proposed for use in a geothermal brine upflow VTE pilot plant. Tests were run at steam temperatures from 250 to 390 deg F, flow rates of 0.5 to 2.5 gpm, and steam to brine DELTA Ts of 10 to 30 deg F using demineralized water and 3% NaCl solutions. In each case the liquid entering the tube flashed through a DELTA T equal to the steam- brine DELTA T. The tubes tested were a 3/4-in. smooth stainless steel tube, a 1-in. double- fluted CuNi tube, and a 7/8-in. double-fluted Al brass tube. Average heat transfer coefficients using 3% NaCl were as follows: for the stainless steel tube, 550 Btu/hr/ deg F/ft/sup 2/ at 250 to 765 at 390 deg F; for the CuNi tube, 2000 at 250 to 2600 at 390 deg F; for the aluminum brass tube, 1750 at 250 deg to about 2650 at 390 deg F. Flow rate and DELTA T, in general, had only small effects on the coefficients. (auth

INVESTIGATION OF MECHANICAL METHODS OF SCALE REMOVAL FROM HRT HEAT EXCHANGERS

Tests were conducted to determine methods of removing scale deposits from the HRT heat exchangers. A mockup of the heat exchanger header was cleared of a deposit of iron rust by reverse flushing at a flow rate below 75 gpm. A tube bundle consisting of 109 1/4 in OD X 0.049 in. wall tubes was plugged with rust. Approximately 80% of these tubes were unplugged by using a 70 psi water pressure differential in combination with vibration from a pneumatic rivet gun. No mechanical method was employed in the tests which could clear the remaining tubes. (auth