Memo

1
Memo 1 Project design conditions

• Objective To determine whether replacement of
  standard oxide fuel in a large BWR by hydride
  fuel will result in a higher power
• Conditions
• Reference core see tables in Lecture 2
• Rod pitch and rod OD are variables, but must fit
  in existing duct
• The number of rods in bundle is a variable
• The hydride fueled fuel assembly has no water
  rods
• Cladding thickness and initial fuel-cladding
  gap are variables, but can be chosen around the
  values in Figs 2.7 and 2.8 of NUREG 1754
• enrichment of hydride fuel not to exceed 20
  oxide ? 5

2

• For calculating the thermal conductivity of
  hydride fuel use kU 0.28 W/cm-K (dispersed
  phase) kZrH
  0.18 W/cm-K (continuous phase)
• Burnup goal Total energy output equivalent to
  60 MWd/kgU in oxide design
• no refueling
• LHR distribution (pending neutronic analysis)

where ? r/Rcore
-1/2 lt z/L lt 1/2

• liquid-metal bond can be used in hydride design
  He bond in oxide

3
Inlet nozzle orificing - none (same flow rate
to all bundles) - to produce the same enthalpy
rise for all bundles

• Constraint on outlet quality 0.23
• maximum pressure drop over core 200 kPa
• main T-H constraint Critical power ratio (CPR)

• fuel composition 21 vol. U metal in ZrH1.6
  or 45 wt U