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%

• 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):

255.0FA e3.1)( where = r/Rcore

2.1L/z53.25.1)z(

-1/2 < z/L < 1/2

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

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