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Tesi etd-01222015-003349


Thesis type
Tesi di laurea magistrale
Author
PEDRETTI, FRANCESCO
URN
etd-01222015-003349
Title
Multi-channel transient analysis of SEALER
Struttura
INGEGNERIA CIVILE E INDUSTRIALE
Corso di studi
INGEGNERIA NUCLEARE
Supervisors
relatore Prof. Forgione, Nicola
relatore Prof. Wallenius, Janne
correlatore Prof. Giusti, Valerio
correlatore Dott.ssa Lo Frano, Rosa
Parole chiave
  • ULOF
  • Doppler coefficient
  • LFR
  • LMFBR
  • safety analysis
  • ULOHS
  • UTOP
  • cladding axial expansion
  • lead fast reactor
  • unprotected accident
  • fast neutron
  • neutronics
  • peak temperature
  • PCT
  • SAS4A/SASSY1
  • lead
  • Serpent
  • reactivity coefficients
  • transient simulations
  • feedback
  • negative feedback
  • loss of heat sink
  • loss of flow
  • over power
  • multi-channel
  • RIA
  • SEALER
  • nuclear safety
  • fuel axial expansion
  • radial expansion
  • transient analysis
  • coolant void worth
Data inizio appello
02/03/2015;
Consultabilità
Completa
Riassunto analitico
The aim of this thesis work is to study the behaviour of SEALER (SwEdish Advanced LEad Reactor) under the three main unprotected accidents that could hypothetically happen for this Lead-cooled Fast Reactor (LFR): Unprotected Transient of Over Power (UTOP), Unprotected Loss Of Flow (ULOF) and Unprotected Loss Of Heat Sink (ULOHS). The work was carried out at the KTH department of Nuclear Reactor Physics, using the SAS4A/SASSYS-1 code.

The first part of the activity consisted of a model development for the reactor core, from the 1-channel one to the 4-channel one, based on the core symmetry and on the different peak factors of fuel assemblies. The main step of this part was the calculation, using the Serpent code, of the channel dependent reactivity coefficients for each channel at the three analysed conditions over the reactor lifetime: Beginning Of Cycle (BOC), Middle Of Cycle (MOC) and End Of Cycle (EOC). The second part of the work consisted of the transient simulations of the reference accidents and of some sensitivity calculations regarding the dependence of the peak fuel and cladding temperatures on the reactivity coefficients.

The obtained results show that, in the studied accident scenarios, the maximum Peak Cladding Temperature (PCT) is less than 1000 K and that the fuel temperature remains under the melting value. Moreover, for the transients UTOP, ULOF and ULOHS with the radiative heat loss through the vessel (ultimate heat sink), a new steady state condition is reached due to the reactivity feedback, while for the ULOHS accident without ultimate heat sink, the reactor is self shutdown.
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