15.6. Nomenclature

Symbols	Description	Units
Superscripts
l	Linear
n	Time step n
‘	Prime always indicates that a quantity refers to a unit of generalized smear volume
Subscripts
ac	Acoustic
bk	Lower boundary of node K
ca	Cavity
cl	Cladding
fica	Free fission gas in molten pin cavity
fr	Friction
fsca	Dissolved fission gas in the molten pin cavity
fuca	Mobile fuel in the molten pin cavity
fufi	Fuel and fission gas
fvca	Fuel vapor in the molten pin cavity
i	Axial coolant channel index, specific enthalpy
if	Interface
K	Axial pin or cavity index
liq	Liquidus
me	Melting, melt-in
min	Minimum
max	Maximum
Na	Sodium
Nl	Liquid sodium
Nv	Sodium vapor
pin,pi	Pin
rl	Dissolved fission-gas release
S’	Sink or source per unit of generalized smear volume
sol	Solidus
un	Uncompressed
vg	Vapor and gas
vi	Viscous
z	Axial location z
Greek
α	Void fraction
β	Delayed neutron fraction
γ	Cp/C:sub:v
δ	Partial derivative
Δ	Derivative in finite differences
κ	Compressibility	1/Pa
π	Circumference of a circle divided by its diameter
ρ	Theoretical density	kg/m3
ρ’	Generalized linear density	kg/m3
σ	Surface tension	J/m2
θ	Generalized volume fraction
Regular
A	Cross section area	m2
A’	Interaction or surface area per unit of generalized smear volume	1/m
AXMX	Input, reference cross section area; recommended input value is subassembly cross section area	m2
BFR	Input, exponent of liquid friction coefficient
BFRV	Input, exponent of vapor friction coefficient
C	Specific heat	J(kg·K)
CDFU	Input, fuel conductivity	J(m·s·K)
CDNL	Input, liquid sodium conductivity	J(m·s·K)
CDVG	Input, conductivity of sodium vapor	J(m·s·K)
CFCOFV	Input, fuel vapor condensation coefficient	J(m2·s·K)
CIA3	Input, constant in the Deissler heat-transfer-correlation
CIFRFU	Input part of the fuel friction calculation
CIREFU	Input, Reynolds number above which fully turbulent fuel flow is assumed for friction calculation
CIRTFS	Input, controls dissolved gas release	1/s
CMFU	Input, liquid fuel compressibility	1/Pa
CPFU	Input, fuel heat capacity	J/(kg·K)
D	Diameter, hydraulic diameter	m
e	Internal energy	J/kg
EGBBLY	Input, internal fuel energy below which fuel freezing begins	J/kg
EGFULQ	Input, internal fuel energy at the liquidus	J/kg
EGFUSO	Input, internal fuel energy at the solidus	J/kg
EPCH	Input, controls use of advanced pressure in in-pin calculation
F	Friction factor
FNFUAN	Input, controls when annular fuel flow in molten pin cavity is assumed
FNMECA	Fraction of node width of radial node on cavity boundaries which melts in per PINACLE time step
FNMELT	Input, controls location of cavity boundary
FNPOE	Relative power level
FUELMS	Initial fuel mass in radial fuel-pin node	kg
FUMASS	Initial total fuel mass in an axial fuel node	kg
FUMS	Current fuel mass in the radial fuel pin node on the cavity boundary	kg
g	Gravity	m/s2
GAMSS	Input, fraction of power going into direct heating of structure
GAMTNC	Input, fraction of power going into direct heating of coolant
GAMTNE	Input, fraction of power going in to direct heating of cladding
h	Heat-transfer coefficient	J/(m2·s·K)
H	Heat-transfer coefficient times heat-transfer area	J/(s·K)
I	Axial node index in coolant channel
IDIFF	Offset between pin and channel grid. The first pin node is at the same elevation as channel node IDIFF + 1
k	Conductivity	J(m·s·K)
K	Axial index in the pin
KKMX	Uppermost node in the molten pin cavity
KZPIN	Coolant channel zone which contains the fuel pins
KK1	Lowermost node in the molten pin cavity
L	Length	m
NRPI	Number of pins per subassembly
NT	Number of radial fuel pin nodes
Nu	Nusselt number
P	Pressure	Pa
PORFR	Porosity fraction
POW	Input, power in highest rated axial fuel pin node	W
POWCOF	Exponent in the exponential function which gives the power history during a neutron’s time step
Pr	Prandtl number
PSHAPE	Input, axial pin power shape
PSHAPR	Input, radial power shape in a pin
Q	Fission heat source
r	Radius	W/kg
R	Gas constant or radius	J/(kg·K)
RETFG2	Total fission gas mass in the radial fuel pin node at the cavity boundary before it began melting into the cavity	kg
Re	Reynold’s number
RGAS	Input, gas constant for fission gas	J(kg·K)
S	Mass sink or source	kg/s
S’	Mass sink or source per unit of generalized smear volume	kg/(m·s)
St	Stanton number
t	Time	S
T	Temperature	K
u	Velocity	m/s
VIFG	Input, viscosity of fission gas	kg/(m·s)
VIFULQ	Input, viscosity of liquid fuel	kg/(m·s)
VOLUME	Volume	m3
z	Axial coordinate	m