New practice for the evaluation of rod efficiency measurement by rod drop at the NPP Paks
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I. Pós
Abstract
Measurement of rod efficiency is an important part of nuclear reactor safety. In case of operating power reactors it is usual to measure all rod efficiency at beginning of cycle hot zero power condition. Measurement of all rod efficiency is technically complicated because the measured “dynamic” reactivity cannot be compared directly to calculated “static” value of control rod efficiency. At Paks Nuclear Power Plant a new method was established to solve this problem. A static computer code used for reload safety analysis was extended to calculate core kinetics as well. Using the developed code the rod drop measurement itself is simulated and the time dependence of flux is determined. In addition, using Monte Carlo calculations weight functions are determined to describe the detector signal response to neutron flux changes in the reactor core. Using this combined system the detector signal itself can be simulated to the actual cycle and condition. Thus the measurement directly can be compared to simulation and the result can be evaluated. The method is under introduction to NPP Paks measurement practice and the first results – which are shown in the paper, are very promising.
Kurzfassung
Beim Betrieb von Kernkraftwerken ist die Kenntnis der Wirksamkeit der Regelstäbe eine sehr wichtige Gröβe, deren Messung ist jedoch schwierig. Üblicherweise wird diese zu Beginn eines Brennstoffzyklus im Zustand „heiβe Nulllast“ gemessen. Dabei ist zu beachten, dass die gemessene dynamische Reaktivität nicht direkt mit der vorausberechneten statischen Stabwirksamkeit verglichen werden kann. Die im KKW Paks hierfür entwickelte neue Methode wird in diesem Beitrag vorgestellt. Dafür wurde ein stationäres Programm, das für Sicherheitsanalysen bei der Neubeladung des Kerns zu Beginn eines neuen Zyklus genutzt wird, um Modelle zur gleichzeitigen Berechnung der Reaktorkinetik erweitert. So simuliert das Programm das Experiment zur Messung der Stabwirksamkeit und bestimmt den zeitabhängigen Neutronenfluss. Zusätzlich werden mit Hilfe von Monte Carlo Berechnungen Wichtungsfaktoren bestimmt, die das Antwortverhalten der Detektorsignale auf Änderungen im Neutronenfluss bestimmen. Dadurch ist es möglich, eine Beziehung zwischen Messsignal und aktuellem Kernzustand zu bestimmen. Somit können die Messungen direkt mit den Berechnungen verglichen. Dieses Verfahren wird derzeit im KKW Paks erprobt und die ersten Ergebnisse sind erfolgsversprechend.
References
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© 2012, Carl Hanser Verlag, München
Articles in the same Issue
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries/Kurzfassungen
- Editorial
- Research on the reactor physics and reactor safety of VVER reactors – Selected contributions to the XXIst Symposium of the Atomic Energy Research organization
- Technical Contributions/Fachbeiträge
- Development of multi-group spectral code TVS-M
- Qualification of the APOLLO2 lattice physics code of the NURISP platform for VVER hexagonal lattices
- The simplified P3 approach on a trigonal geometry of the nodal reactor code DYN3D
- An analytical solution for the consideration of the effect of adjacent fuel assemblies; extension to VVER-440 type fuel assemblies
- Studies on boiling water reactor design with reduced moderation and analysis of reactivity accidents using the code DYN3D-MG
- Simulations of RUTA-70 reactor with CERMET fuel using DYN3D/ATHLET and DYN3D/RELAP5 coupled codes
- Analysis of coolant flow in central tube of VVER-440 fuel assemblies
- Effect of spacer grid mixing vanes on coolant outlet temperature distribution
- Study on severe accidents and countermeasures for VVER-1000 reactors using the integral code ASTEC
- Assessment of spectral history influence on PWR and WWER core
- New practice for the evaluation of rod efficiency measurement by rod drop at the NPP Paks
- Comparison of square and hexagonal fuel lattices for high conversion PWRs
- VVER-440 with inert matrix fuel – viable direction to sustainability
Articles in the same Issue
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries/Kurzfassungen
- Editorial
- Research on the reactor physics and reactor safety of VVER reactors – Selected contributions to the XXIst Symposium of the Atomic Energy Research organization
- Technical Contributions/Fachbeiträge
- Development of multi-group spectral code TVS-M
- Qualification of the APOLLO2 lattice physics code of the NURISP platform for VVER hexagonal lattices
- The simplified P3 approach on a trigonal geometry of the nodal reactor code DYN3D
- An analytical solution for the consideration of the effect of adjacent fuel assemblies; extension to VVER-440 type fuel assemblies
- Studies on boiling water reactor design with reduced moderation and analysis of reactivity accidents using the code DYN3D-MG
- Simulations of RUTA-70 reactor with CERMET fuel using DYN3D/ATHLET and DYN3D/RELAP5 coupled codes
- Analysis of coolant flow in central tube of VVER-440 fuel assemblies
- Effect of spacer grid mixing vanes on coolant outlet temperature distribution
- Study on severe accidents and countermeasures for VVER-1000 reactors using the integral code ASTEC
- Assessment of spectral history influence on PWR and WWER core
- New practice for the evaluation of rod efficiency measurement by rod drop at the NPP Paks
- Comparison of square and hexagonal fuel lattices for high conversion PWRs
- VVER-440 with inert matrix fuel – viable direction to sustainability
