ISSN:0029-5450    

DOI:10.13182/NT87-A33978

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

The physical processes taking place during the dispersion of releases of pollutants into the atmosphere and the hydrosphere (surface as well as groundwaters) can be mathematically modeled. The analytical methods available for tracking pollutants in the atmosphere include local and mesoscale models (mostly based on Gaussian-plume dispersion), as well as regional and global models, where either more sophisticated numerical techniques or“box”modeling is used. Various removal processes such as physicochemical transformations, wet and dry deposition, resuspension, and plume rise affect aerial dispersion. The mechanisms of transport in surface waters include mass transport by the waters themselves, dispersion, sedimentation, boundary exchange processes, and various forms of depletion. The models vary according to the type of surface waters considered: rivers, estuaries and tidal rivers, small lakes, open-coast water bodies, etc. Regarding groundwater transport, one must distinguish between saturated and unsaturated zones and homogeneous or nonhomogeneous media. Numerous references refer the reader to details and to state-of-the-art treatment of the subjects.

ISSN:0029-5450    

DOI:10.13182/NT87-A33979

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Including fission product vapor interactions with aerosols in reactor accident calculations can significantly alter the predicted consequences of a given accident. For example, a high-velocity, short residence time accident can transport significant amounts of tellurium outside the reactor vessel on the aerosols rather than having the tellurium reacted on the vessel’s metal surfaces. In another scenario, a relatively stagnant situation allows equilibration of the vapor/aerosol interactions and deposition of the aerosols inside the core region. Consequently, most of the fission product vapors remain in the core region with the deposited aerosols. The sorption isotherms of CsOH-Ag, CsOH-Cr2O3, and CsI-Cr2O3can be represented by modified Freundlich isotherm expressions. In addition, CsOH vapor interacts extremely with the iron species under accident conditions such that 0.6 wt% FeO in the aerosol can remove 10 to 15 wt% of the CsOH emitted in an accident.

ISSN:0029-5450    

DOI:10.13182/NT87-A33980

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

A new model has been developed for predicting the rate at which gaseous molecular iodine is absorbed by water sprays. This model is a quasi-steady-state mass transfer model that includes iodine hydrolysis reactions. The parameters of the model arespray drop sizeinitial concentration of the gas and liquid phasestemperaturepressurethe buffered or unbuffered state of the spray solutionspray flow ratecontainment diameterdrop-fall height.Results from the model were compared with the results available from the Containment Systems Experiments carried out at Pacific Northwest Laboratory in 1970. The difference between results predicted by the model and the experimental data ranges from−120.5 to 68.0%. The new spray model was also compared to previous spray models. At high concentrations of molecular iodine in the gas, the new spray model is less accurate than an earlier model in predicting available data; however, the new model is believed to be more reliable for extrapolation. At low concentrations, the new model predicts results that are closer to the experimental data than earlier models. The principal advantage of the new model is its potential ability to account for iodine hydrolysis reactions and changes that occur in iodine removal rates as high concentrations of iodine accumulate in the water. Inclusion of the iodine hydrolysis reactions is shown to be important for determining the rate of molecular iodine removal over a wide range of conditions.

ISSN:0029-5450    

DOI:10.13182/NT87-A33981

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Thermal plutonium recycling has been demonstrated by Kraftwerk Union AG/Alkem on a large scale since 1972 in power plants at Obrigheim and Gundremmingen, Federal Republic of Germany (FRG). An improved mixed-oxide (MOX) fuel fabrication technology has been available since 1981. Such improved MOX fuel is currently being used at Obrigheim, Neckarwestheim, Unterweser, Grafenrheinfeld, FRG, and Beznau 2, Switzerland. The MOX fuel assemblies currently inserted exhibit an operating performance that is comparable to that of uranium fuel assemblies. Postirradiation investigations on MOX fuel show high mechanical stability, low shrinkage and swelling, and good behavior during power transients. On the basis of this experience, large-scale use of MOX fuel is technically feasible.

ISSN:0029-5450    

DOI:10.13182/NT87-A33982

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Two 38-mm-diam, 5-m-high pulse columns are investigated to evaluate the droplet diameters and axial mixing in the comparison of the aqueous to organic continuous mode of operation. It is observed that the average droplet diameters are dominated by pulse intensity and are independent of throughputs. Through the evaluation of axial eddy diffusivities, it is concluded that the axial diffusivity coefficient depends mainly on pulse intensity, and the value for the disperged phase is similar to that for the continuous phase at the same pulse intensity.

ISSN:0029-5450    

DOI:10.13182/NT87-A33983

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Two mathematical models have been derived for chemical decontamination of nuclear reactor films, starting from mass transfer and kinetic fundamentals. The first model predicts a linear field decrease with time, while the second model implies an exponential decrease. Both models are compared to Westinghouse experimental data. The exponential model agrees very well with the boiling water reactor decontamination data, generating gross rate constants of 0.875 to 1.105 h−1at 121°C. Neither model correlates well with the pressurized water reactor data. This modeling exercise indicates that field decrease versus time is a better approach than the raw“decontamination factor”normally presented in the literature. It also suggests that specimen effective surface area and related properties should be measured. Both avenues should be pursued in future decontamination programs.

ISSN:0029-5450    

DOI:10.13182/NT87-A33984

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

A unique evaporation/thermal denitration process was developed, operated, and maintained successfully at Oak Ridge National Laboratory to permit the solidification and safe storage of∼1000 kg of highly radioactive and fissile uranium, containing∼75%235U,∼10%233U, and∼140 ppm232U. The project, called the Consolidated Edison Uranium Solidification Program, was carried out to prepare a stable uranium form for long-term, safe storage. During the project, the uranium nitrate solution was divided into∼400 batches, which were successfully processed. Details of the process development, equipment maintenance, and operating expertise are described.

ISSN:0029-5450    

DOI:10.13182/NT77-210

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Calibration curves are determined for measuring the concentration of10B in the blood of rats using an autoradiographic procedure, with the polycarbonate solid-state nuclear track detector CR-39 and an image analysis system for automatic track counting. The calibration curves indicate that for the etch procedure used, the nitrogen concentration in the blood is an important interfering input for10B concentration measurements. By discriminating against small tracks, the sensitivity to the blood nitrogen concentration can be reduced to the point that a variation in the nitrogen weight fraction of 0.01 gN/g blood causes a variation in the predicted10B concentration of 0.3µg10B/ml blood.

ISSN:0029-5450    

DOI:10.13182/NT87-A33986

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractA Monte Carlo departure from nucleate boiling ratio (DNBR) limit analysis has recently been performed with a six-channel thermal-hydraulics code model as the tool for DNBR calculations. Compared is the use of the few-channel, fast-running code models with the use of a response surface model as the DNBR calculator. The latter had been used to date for Monte Carlo analyses. The principles of Monte Carlo DNBR limit determination are reviewed to provide the necessary background information.

ISSN:0029-5450    

DOI:10.13182/NT87-A33987

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor