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[en] Highlights: • Model calibration method for BEPU was developed with optimization method. • Nonparametric statistics method with Wilks was used for Sherwood uncertainties. • SCOPE test data was applied to calibrate condensation model. - Abstract: Quantification of model input uncertainties is very important to development of Best-estimate plus uncertainty (BEPU) accident analysis method. In particular, condensation model uncertainty on the Sherwood number should be quantified accurately in the development of containment response BEPU analysis method. In this paper, Sobol’s total indices were used to assess the parameter sensitivity, nonparametric statistics method with Wilks correlation was used to quantify the Sherwood number uncertainties, and calibration intervals of the condensation factor were obtained with an optimization method. The objective of the optimization was to ensure that the Sherwood number uncertainties quantified from test data were enveloped by those calculated from model prediction. The optimization process was automatically implemented with specified objective function and constraint condition. The results show that the developed method is able to reasonably determine the condensation model calibration interval. The method presents high accurateness, robustness and flexibility and could be conveniently applied to model uncertainty quantification based on separate effects tests and simple integral effect tests.

[en] The results of experimental investigation of heat exchange at the condensation of water vapor from vapor-air mixtures are presented. The experimental investigations are carried out on the models of surface and bubbling-type condensers. The results obtained are shown in the form generalizing relations. Devised methods can be recommended for calculation surface and bubbling-type condensers. (Author)

[en] During the summer of 1980 the condenser tubes of Barsebaeck 2 were acid cleaned due to the following reasons: 1) significant heat transfer losses 2) possible passivation of attacks filled with corrosion products 3) encouraging experiences from acid cleaning of Danish units 4) less encouraging experiences from mechanical cleaning. Prior to the acid cleaning some laboratory experiments were performed to investigate the effect of pH-value and temperature on the time required for cleaning. In spite of practical problems including loss of acid and cavitating pumps the acid cleaning was performed in less than 24 hours/condenser section. The result of the acid cleaning was better than the result of mechanical methods employed earlier. There was a significant increase in heat transfer efficiency. In two of the condenser sections the tubes were completely free of corrosion products after acid cleaning and cleaning with the Taprogge system. In the two remaining condenser sections some corrosion products were observed in a few deep attacks. This is due to a higher pH-value suring the cleaning of these two sections than during the cleaning of the two first sections. There were no indications of any acid leaking to the steam side of the condenser. (Author)

[en] At Darlington Nuclear Generating Station (DNGS), very large pipes (60' diameter for service water and 72' diameter for condenser cooling water (CCW)) deliver water to maintain reactor cooling and power plant optimal operation. Conditions that restrict flow in these pipes exist, and work programs are implemented to minimize flow impediment. Due to lack of flow indicators, effectiveness of these work programs are difficult to measure. In order to determine the most effective method for flow impediment reduction, flow measurement in these pipes are required. Ultrasonic flow meter is the ideal instrument for obtaining flow readings in these pipes. However, very large pipes pose various challenges for ultrasonic flow meters. These challenges must be overcome to ensure successful measurement. This document chronicles the innovative solutions that IRI personnel derived to overcome these challenges to successfully use Ultrasonic Cross Correlation Flow Meter (USCCFM) to measure flow in the 72' pipes. (author)

[en] Wet cooling towers can be used as ''helper''systems with once-through cooling at river-side power-plant sites where the permissible river heat assimilation capacity is inadequate to absorb all of the waste heat. A comprehensive computer model is used for the thermodynamic analysis, economic assessment, and optimum design of once-through/wet tower hybrid cooling systems. Several different configurations are investigated, and results are presented for an 1,150 MW nuclear power plant located on the Missouri River at Sioux City, Iowa. The hybrid cooling system arranged in a series water path with a partially closed-cycle loop appears to be the most economical configuration for the site conditions studied when zero water costs are used. Comparison of hybrid systems with once-through cooling and closed-cycle wet tower systems indicate that hybrid cooling systems are economically superior. A trade-off function between total cost and water evaporation is presented to indicate the best hybrid arrangement for sites where water availability is limited. 16 refs

[en] Extensive tests indicate that presently recognized standard methods for calculting pressure drops in raw water piping do not allow for required flow over a 40-yr projected operating lifetime of the piping. Changes in the recommended design practices are suggested. In particular, the use of a modified Hazen-Williams equation instead of a modified Darcy equation is recommended

[en] Sea water impurities hide out within thin (∼10 μm) deposits on steam generator tubes, as demonstrated by both laboratory studies using segments of fouled steam generator tubes pulled in 1992 from Crystal River-3 nuclear power station and field hideout return studies performed during recent plant shutdowns. Laboratory tests performed at 279^oC (534^oF) and heat fluxes ranging from 35 to 114 kW/m² (11,100 - 36,150 Btu/h.ft²), conditions typical of the lower tubesheet to the first support plate region of a once-through steam generator, showed that impurity hideout can occur in thin free-span tube deposits. The extent of hideout increased with increasing heat flux. Soluble species, such as sodium and chloride ions, returned promptly to the bulk water from the deposits when the heat flux was turned off, whereas less soluble species, such as calcium sulfate and magnesium hydroxide, returned more slowly. Recent field hideout return studies performed at Crystal River-3 where the water level in the steam generators was maintained below the first tube support plate during the shutdown, thus wetting only the thin deposits in the free span and the small sludge pile, corroborate the laboratory findings, showing that hideout does indeed occur in the free-span regions of the tubes. These findings suggest that hideout within tube deposits has to be accounted for in the calculation of crevice chemistry from hideout return studies and in controlling the bulk chemistry using the molar ratio criterion. (author). 3 refs., 4 tabs., 3 figs

[en] Short communication

[en] The condenser, which has titanium tubes roller-expanded in tube plates of clad steel (type 316), revealed no corrosion attack requiring protective measures apart from those already adopted - sacrificial anodes of soft iron during operation and continuous freshwater rinsing of the tube plates during shutdown. The surfaces of the tube plates which were experimentally coated with min 500 μm solvent-free epoxy coating were in very good condition. (author)