Single Phase 41
1
A PWR has dimensions and operating conditions given below.
Core Thermal Output
3817 Mw
Fuel Height
150 inches
Rod Pitch
0.506 inches
Outer Clad Diameter
0.382 inches
Power Peaking Factor
2.348
Axial Peak to Average Ratio
1.4
Number of Fuel Rods
56,876
Energy Deposited in Fuel
97 %
Core Inlet Loss Coefficient
1.5
Core Exit Loss Coefficient
1.5
Grid Loss Coefficient
0.5
Number of Grids/assembly
8
Where the axial heat flux profile is of the form
′′
=
′′
+
⎛
⎝
⎜
⎞
⎠
⎟
q
z
q
z
H
e
( )
sin
(
)
0
π
λ
Upon shutdown, the fuel from this reactor is to be placed within the spent fuel storage pool.
a) Assuming the inlet temperature to the fuel assemblies can be maintained at 80 F, what must be the minimum
decay time such that no bulk boiling occurs within the highest powered assemblies?
What if the pool
temperature could be maintained at 100 F?
b) What are the flow conditions at this time, i.e. laminar or turbulent?
c) Assuming the Weisman correlation holds within the rod bundles, what must be the minimum decay time such
that no boiling occurs on the rod surfaces in the highest powered assemblies?
d) Natural circulation heat transfer coefficients for vertical cylinders are of the form
m
C(GrPr)
Nu
=
where:
number
Nusselts
k
L
h
Nu
c
=
≡
number
Grashof
L
)
T
T
(
g
Gr
2
3
w
2
=
−
≡
∞
μ
βρ
number
Prandtl
k
C
Pr
p
=
≡
μ

This
** preview**
has intentionally

**sections.**

*blurred***to view the full version.**

*Sign up*