Study on the impact of transition from 3-batch to 4-batch loading at Loviisa NPP on the long-term decay heat and activity inventory
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T. Lahtinen
Abstract
The fuel economy of Loviisa NPP was improved by implementing a transition from 3-batch to 4-batch loading scheme between 2009 and 2013. Equilibrium cycle length as well as all process parameters were retained unchanged while the increase of fuel enrichment enabled to reduce the annual reload batch size from 102 to 84 assemblies. The fuel cycle transition obviously had an effect on the long-term decay heat and activity inventory. However, due to simultaneous change in several quantities the net effect over the relevant cooling time region is not self-evident. In this study the effect is analyzed properly, i. e. applying consistent calculation models and detailed description of assembly-wise irradiation histories. The study concludes that for the cooling time, foreseen typical prior to encapsulation of assemblies, the decay heat of discharge batch increases 2 – 3%. It is also concluded that, in order to maintain 100% filling degree of final disposal canisters, the cooling time prior to encapsulation needs to be prolonged by 10 – 15 years.
Kurzfassung
Die Wirtschaftlichkeit des KKW Loviisa wurde zwischen 2009 und 2013 durch den Übergang vom 3- zum 4-Jahres-Zyklus verbessert. Während die Länge des Gleichgewichtszyklus und alle Prozessparameter unverändert blieben, wurde durch die erhöhte Brennstoffanreicherung die jährliche Neubeladungsmenge von 102 auf 84 Brennelemente reduziert. Diese Änderung im Brennstoffzyklus hat einen deutlichen Einfluss auf die langfristige Nachzerfallswärme und auf das Aktivitätsinventar. Allerdings ist aufgrund der gleichzeitigen Veränderung mehrerer Größen der Nettoeffekt während der relevanten Abklingzeit nicht selbsterklärend. In dieser Studie wird der Effekt detailliert analysiert durch die Anwendung konsistenter Berechnungsmodelle und einer detaillierten Beschreibung der Brennelementweise berücksichtigten Bestrahlungshistorie. Die Studie kommt zu dem Schluss, dass während der Abklingzeit, die typischerweise vor der Lagerung der Brennelemente einzuhalten ist, die Nachzerfallswärme dieser ausgetauschten Menge um 2 – 3% ansteigt. Zudem wird auch gefolgert, dass daher die Abklingzeit um 10 – 15 Jahre verlängert werden muss, um einen 100% igen Füllgrad der endgültigen Entsorgungsbehälter zu erreichen.
References
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© 2017, Carl Hanser Verlag, München
Articles in the same Issue
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Editorial
- Research on the reactor physics and reactor safety of VVER reactors – AER Symposium 2016
- Technical Contributions/Fachbeiträge
- Physical startup tests for VVER-1200 of Novovoronezh NPP: advanced technique and some results
- Experimental study of asymmetric boron dilution at VVER-1000 of Kudankulam NPP and its simulation
- Study on the impact of transition from 3-batch to 4-batch loading at Loviisa NPP on the long-term decay heat and activity inventory
- New engineering safety factors for Loviisa NPP core calculations
- Development of fuel cycles with new fuel with 8.9 mm external diameter for VVER-440: Preliminary assessment of operating efficiency
- Investigation of circulating temperature fluctuations of the primary coolant in order to develop an enhanced MTC estimator for VVER-440 reactors
- Recalculating the steady state conditions of the V-1000 zero-power facility at Kurchatov Institute using Monte Carlo and nodal diffusion codes
- Start-up of a cold loop in a VVER-440, the 7th AER benchmark calculation with HEXTRAN-SMABRE-PORFLO
- Verification results of methodology for determining the weighted mean coolant temperature in the primary circuit hot legs of WWER-1000 reactor plants
- Advances in HELIOS2 nuclear data library
- ANDREA 2.2 and 2.3 – Advances in modelling of VVER cores
- CFD analyses of the rod bowing effect on the subchannel outlet temperature distribution
- A methodology for the estimation of the radiological consequences of a Loss of Coolant Accident
- Neutron balance as indicator of long-term resource availability in growing nuclear energy system
- Analysis of changes in the fuel component of the cost of electricity in the transition to a closed fuel cycle in nuclear power system
- Experimental and numerical thermal-hydraulics investigation of a molten salt reactor concept core
Articles in the same Issue
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Editorial
- Research on the reactor physics and reactor safety of VVER reactors – AER Symposium 2016
- Technical Contributions/Fachbeiträge
- Physical startup tests for VVER-1200 of Novovoronezh NPP: advanced technique and some results
- Experimental study of asymmetric boron dilution at VVER-1000 of Kudankulam NPP and its simulation
- Study on the impact of transition from 3-batch to 4-batch loading at Loviisa NPP on the long-term decay heat and activity inventory
- New engineering safety factors for Loviisa NPP core calculations
- Development of fuel cycles with new fuel with 8.9 mm external diameter for VVER-440: Preliminary assessment of operating efficiency
- Investigation of circulating temperature fluctuations of the primary coolant in order to develop an enhanced MTC estimator for VVER-440 reactors
- Recalculating the steady state conditions of the V-1000 zero-power facility at Kurchatov Institute using Monte Carlo and nodal diffusion codes
- Start-up of a cold loop in a VVER-440, the 7th AER benchmark calculation with HEXTRAN-SMABRE-PORFLO
- Verification results of methodology for determining the weighted mean coolant temperature in the primary circuit hot legs of WWER-1000 reactor plants
- Advances in HELIOS2 nuclear data library
- ANDREA 2.2 and 2.3 – Advances in modelling of VVER cores
- CFD analyses of the rod bowing effect on the subchannel outlet temperature distribution
- A methodology for the estimation of the radiological consequences of a Loss of Coolant Accident
- Neutron balance as indicator of long-term resource availability in growing nuclear energy system
- Analysis of changes in the fuel component of the cost of electricity in the transition to a closed fuel cycle in nuclear power system
- Experimental and numerical thermal-hydraulics investigation of a molten salt reactor concept core
