Neutronic and Thermal-hydraulic Modelling of High Performance Light Water Reactor: Master's thesis

Malla Seppälä

Research output: ThesisMaster's thesis


High Performance Light Water Reactor (HPLWR) is a new reactor concept that operates at supercritical pressure conditions. VTT participates in the 'HPLWR2' project, in which the technological feasibility and economical competitiveness of the concept are assessed, by calculating coupled neutronic and thermal-hydraulic analysis of the HPLWR plant. An advanced core model TRAB-3D was chosen for neutronics calculation internally coupled to thermal-hydraulic system code SMABRE. The work done for this thesis is part of VTT's contribution to the project.

To initiate the modelling of HPLWR at VTT, a thorough literature survey on the current state of the design was done in this thesis. Based on the gathered data, input models of the HPLWR plant were made for TRAB-3D and SMABRE. The capability of SMABRE to calculate supercritical pressure conditions were shown by calculating the Edwards-O'Brien blowdown test modified to supercritical pressures. A functioning thermal-hydraulic steady-state for the HPLWR model was achieved with SMABRE. However, due to complications with SMABRE, testing of the coupled model could not be started yet.

In addition to the coupled transient analysis, two-group constants for HPLWR fuel assembly were generated with PSG Monte Carlo neutron transport code developed at VTT. The results were compared to parameterized cross sections received from Hungarian Academy of Sciences KFKI Atomic Energy Research Institute. Reference values for infinite multiplication factor were calculated also with MCNP4C.
Original languageEnglish
QualificationMaster Degree
Awarding Institution
  • Helsinki University of Technology
  • Salomaa, Rainer, Supervisor, External person
  • Daavittila, Antti, Advisor, External person
Place of PublicationEspoo
Publication statusPublished - 2008
MoE publication typeG2 Master's thesis, polytechnic Master's thesis


  • fission
  • nuclear
  • Generation IV, supercritical water reactor
  • High Performance Light Water Reactor
  • neutronics
  • thermal-hydraulics
  • cross section


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