Core Physics Analysis

XIX-10] KUIJPER, J.C., DE HAAS, J.B.M., AND OPPE, J., HTR core physics analysis at NRG, L Topical Meeting on High Temperature Reactor Technology (Proc. Int. Conf Petten, Netherlands, April 22-24, 2002). 

A Level 1 PSA is a core-melt analysis that may or may not include external events a Level 2 PSA encompasses Level 1 and extends to the physical processes of the accident and their effect on containment a Level 3 PSA encompasses Levels 1 and 2 and extends to public risk. 

The first step in the tube approach is to use the pathways idea to isolate routes through the protein that are physically distinct (see the example in the next section), and then use these paths as tube cores. The analysis then proceeds with an emphasis on partitioning the protein into tubes the tubes contain trivial interference effects, but they can expose crucial interference between tubes. This is something which one cannot do in the single-pathway approximation. 

To enhance the accuracy and reliability of large FBR design work in Japan, the quantitative knowledge obtained from the JUPITER experiments and analysis will be utilized as one of the most important databases for FBR core physics. 

An anticipated difference between the ATHR and helium-cooled reactors is the coolant void coefficient of reactivity, since the relevant nuclear cross sections for molten salts are larger than those for helium. The void coefficient corresponds to the amount of reactivity that is added or subtracted by complete removal of the coolant. Since initial AHTR calculations indicated that the void coefficient could be positive or negative depending on the precise design of the core, the focus of the physics analysis effort was to characterize this effect more carefully. 

A series of neutronics calculations were conducted to evaluate the coolant void coefficient and to understand its sensitivity to various core parameters. Both ORNL and SNL participated in the physics analysis using slightly different models and assumptions. The results are in good agreement, however. 

The design process utilized published information on the General Atomics MHTGR to the extent feasible. Physics analysis to confirm the characteristics of the Lead (208),and other lead and lead alloy coolants, and the fundamental neutronic and thermohydraulic core behaviour was completed. 

STANDARD PROBLEM ANALYSIS CORE PHYSICS LWR FUEL LMFBR FUEL... 

Core physics benchmarks, on the other hand, must be representative of the reactor system of interest. They are designed to test reactor analysis methods in their intended areas of application. Thus, characteristic physical features such as geometric heterogeneities, water gaps, voids, burnable poison rods, etc., must be represented. 

The ASTRA critical facility at the Russian Research Centre Kurchatov Institute (RRC KI), Moscow, the Russian Federation was utilized to perform benchmark analysis of the pebble bed core physics and neutronic codes [XIV-2],... 

The CAPP code (Lee et al., 2012a,b) is used for the analysis of core physics parameters of VHTR using the few-group parameters generated by DeCART. The sensitivity and uncertainty analysis code, MUSAD (Han et al., 2015), is being developed for an uncertainty analysis of the few-group parameters generated by DeCART and eventually the uncertainty of the core physics parameters evaluated by the CAPP code. Fig. 13.11 shows the two-step neutronics analysis code system for the VHTR developed at KAERI. 

Liu, X.J., Cheng, X., 2010. Coupled thermal-hydraulics and neutron-physics analysis of SCWR with mixed spectrum core. Progress in Nuclear Energy 52 (7), 640—647. 

PHWR safety analysis requires a comprehensive set of physical models. Reactor physics analysis may require a transient three dimensional model for the large PHWR cores. The most demanding application is a large LOCA, because of the relatively fast kinetics and the spatial effects associated with flux tilts and shut-off rod (or liquid absorber) insertion. Three dimensional effects are also important in slow loss of reactivity control starting from distorted flux shapes. 

Success criteria were extracted from information contained in plant procedures, supplemented by the PRA team s experience with the plant reviews of existing SRS engineering/physics analysis and analyses done in support of the PRA. Additional thermal-hydraulic analysis to refine some of the success criteria is planned for 1991. It is expected that the impact of improved success criteria will be a reduction in the estimated core damage frequency. Therefore, this issue does not require resolution before restart. 

The CPT is responsible for integration and implementation of the core design and safety analyses, which includes responsibility for design specifications, verification that fuel received is within specifications, verification that core conditions lie within core design and safety analysis criteria, operating limits, physics ihd thermal-hydraulic data for operational assessment and operational data for core design and safety analyses. The CPT is also responsible for core performance analysis which includes estimated critical position predictions, shutdown reactivity predictions, control rod worth curves, operational anomaly analysis and observed performance summaries. 

X. J. Liu and X. Cheng, Coupled Thermal-Hydraulics and Neutron-Physics Analysis of SCWR with Mixed Spectrum Core, Proc. 4th Int. Symp. on SCWR, Heidelberg, Germany, March 8-11, 2009, Paper No. 44 (2009)... 

Ithough knowledge-based potentials are most popular, it is also possible to use other types potential function. Some of these are more firmly rooted in the fundamental physics of iteratomic interactions whereas others do not necessarily have any physical interpretation all but are able to discriminate the correct fold from decoy structures. These decoy ructures are generated so as to satisfy the basic principles of protein structure such as a ose-packed, hydrophobic core [Park and Levitt 1996]. The fold library is also clearly nportant in threading. For practical purposes the library should obviously not be too irge, but it should be as representative of the different protein folds as possible. To erive a fold database one would typically first use a relatively fast sequence comparison lethod in conjunction with cluster analysis to identify families of homologues, which are ssumed to have the same fold. A sequence identity threshold of about 30% is commonly... 

Given the damage states, the analysis flows much as shown in Figure 6.3-1, depending on the process. For a nuclear power plant, thermal-hydraulic analyses determine the spatial temperature of the damaged core, and consequently the ability of the core to retain radioactive materials. Analysis of the physical processes reveals the amounts of hazardous materials that may be released. 

The analysis of the consequences of nuclear accidents began with physical concepts of core melt, discussed the mathematical and code models of radionuclide release and transport within the plant to its release into the environment, models for atmospheric transport and the calculation of health effects in humans. After the probabilities and consequences of the accidents have been determined, they must be assembled and the results studied and presented to convey the meanings. 

The physical basis of AES involves three basic steps, namely atomic ionization (by the removal of a core electron), electron emission (the Auger process), and analysis of the emitted Auger electrons. 

Gomes, J.D., Sousa, M.H., Tourinho, F.A. and Aquino, R. da Silva, G.J., Depeyrot, J., Dubois, E., Perzynski, R. (2008) Synthesis of core-shell ferrite nanopartides for ferrofluids chemical and magnetic analysis. Journal of Physical Chemistry C, 112 (16), 6220-6227. 

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