Advanced thermohydraulic simulation code for pool-type LMFBRs (SSC-P code)

Models for components and processes that are needed for simulation of thermohydraulic transient in a pool-type liquid metal fast breeder reactor (LMFBR) plant are described in this report. A computer code, SSC-P, has been developed as a part of the Super System Code (SSC) development project. A user's manual is being prepared as a separate document. 27 refs., 26 figs., 1 tab

Modeling and analysis of low heat flux natural convection sodium boiling in LMFBRs

Flow excursion induced dryout at low heat flux natural convection boiling, typical of liquid metal fast breeder reactor, is addressed. Steady state calculations indicate that low quality boiling is possible up to the point of Ledinegg instability leading to flow excursion and subsequent dryout in agreement with experimental data. A flow regime-dependent dryout heat flux relationship based upon saturated boiling criterion is also presented. Transient analysis indicates that premature flow excursion can not be ruled out and sodium boiling is highly transient dependent. Analysis of a high heat flux forced convection, loss-of-flow transient shows a significantly faster flow excursion leading to dryout in excellent agreement with parallel calculations using the two-dimensional THORAX code. 31 refs., 25 figs., 6 tabs

A simplified model for calculating early offsite consequences from nuclear reactor accidents

A personal computer-based model, SMART, has been developed that uses an integral approach for calculating early offsite consequences from nuclear reactor accidents. The solution procedure uses simplified meteorology and involves direct analytic integration of air concentration equations over time and position. This is different from the discretization approach currently used in the CRAC2 and MACCS codes. The SMART code is fast-running, thereby providing a valuable tool for sensitivity and uncertainty studies. The code was benchmarked against both MACCS version 1.4 and CRAC2. Results of benchmarking and detailed sensitivity/uncertainty analyses using SMART are presented. 34 refs., 21 figs., 24 tabs

An integral approach for calculating uncertainties in consequences from nuclear reactor accidents

This paper presents a Personal Computer-based model that uses an integral approach for calculation of early off-site consequences resulting from nuclear power plant accidents. The computing time requirements for a typical calculation on a mainframe computer using this model are two orders of magnitude lower than those of CRAC2 and MACCS codes, thus providing a valuable tool for sensitivity and uncertainty studies. The model predicts time-integrated air concentration of each radionuclide at any location from release as a function of time-integrated source strength using the Gaussian plume model. The concentration can be calculated at the centerline of a Gaussian profile or, optionally, as an average over the cross-section based on a top-hat distribution. The solution procedure involves direct analytic integration of air concentration equations over time and position. This is different from the differential approach currently used in CRAC2 and MACCS codes. The present model uses simplified meteorology. Dispersion parameters are calculated from exponential fits to the Pasquill-Gifford curves for six atmospheric stability classes designated A to F, and from an approximation as indicated in Reg. guide 1.145 for the seventh stability class G (extremely stable). 8 refs., 2 figs

Benchmark Exercise on Expert Judgement Techniques in PSA Level 2.

Abstract not availableJRC.(ISIS)-Institute For Systems, Informatics And Safet

CHARM HADRON PROPERTIES IN 400-GeV/c p p INTERACTIONS

A study of the properties of charm particles produced in 400 GeV/cpp interactions is reported. The experiment was performed using the high resolution hydrogen bubble chamber LEBC in association with the European Hybrid Spectrometer at the CERN SPS. Details of the experimental set-up and operational procedures are given and the methods to extract samples of charm decays are discussed. Results are presented on the intrinsic properties of charm particles (masses, lifetimes, decay modes and branching ratios), adding, whenever appropriate, the relevant information obtained in a similar study made with 360 GeV/c\u3c0 12 p interactions. The hadroproduction properties of charm states (total and differential cross sections, correlations) are presented and discussed in the context of current QCD inspired phenomenology