Shutdown margin for high conversion BWRs operating in Th-233U fuel cycle

Y. Shaposhnik, E. Shwageraus, E. Elias

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Several reactivity control system design options are explored in order to satisfy shutdown margin (SDM) requirements in a high conversion BWRs operating in Th-233U fuel cycle (Th-RBWR). The studied core has an axially heterogeneous fuel assembly structure with a single fissile zone "sandwiched" between two fertile blanket zones. The utilization of an originally suggested RBWR Y-shape control rod in Th-RBWR is shown to be insufficient for maintaining adequate SDM to balance the high negative reactivity feedbacks, while maintaining fuel breeding potential, core power rating, and minimum Critical Power Ratio (CPR). Implementation of alternative reactivity control materials, reducing axial leakage through non-uniform enrichment distribution, use of burnable poisons, reducing number of pins as well as increasing pin diameter are also shown to be incapable of meeting the SDM requirements. Instead, an alternative assembly design, based on Rod Cluster Control Assembly with absorber rods was investigated. This design matches the reference ABWR core power and has adequate shutdown margin. The new concept was modeled as a single three-dimensional fuel assembly having reflective radial boundaries, using the BGCore system, which consists of the MCNP code coupled with fuel depletion and thermo-hydraulic feedback modules.

Original languageEnglish
Pages (from-to)162-177
Number of pages16
JournalNuclear Engineering and Design
StatePublished - 1 Jan 2014

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • General Materials Science
  • Safety, Risk, Reliability and Quality
  • Waste Management and Disposal
  • Mechanical Engineering


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