7.6. Nomenclature

Symbol	Definition	Units
$a$	Constant $\left( 9.325 \times 10^{-2} \right)$
$a_{0}, a_{1}, a_{2}, a_{3}$	Momentum equation coefficients
$A$	Flow area	$m^{2}$
$b$	Constant $\left( 2.356 \times 10^{-4} \right)$
$B$	Valve damping coefficient	$kg - m / s$
$c, c_{p}$	Specific heat	$J / kg - K$
$c_{b}$	Bucket coefficient
$c_{n}$	Nozzle velocity coefficient
$c_{r}$	Reaction coefficient
$C$	Valve calibration constant	$m^{2}$
$CF$	Calibration factor
$CV$	Elevation of heater center	$m$
$C_{1},\ C_{2},\ C_{3},\ C_{4}$	Coefficients in the expression for the Moody friction factor ($C_{1}=0.0055$, $C_{2}=20000$, $C_{3}=106$, and $C_{4}=1/3$)
$D_{h},\ D_{H}$	Hydraulic diameter	$m$
$\widehat{E}$	Total energy	$J / kg$
$f_{l}$	Liquid friction factor
$f_{tp}$	Two-phase friction factor
$F$	Force	$N$
$F$	Heat flux	$W / m^{2}$
$F$	Pressure loss coefficient
$FL$	Fouling resistance	$m^{2} - K / W$
$FR$	Friction calibration coefficient
$F_{1}$	Valve driving function	$kg - m / s^{2}$
$g$	Gravitational constant	$m / s^{2}$
$G$	Mass flux	$kg / m^{2} - s$
$G_{2}$	Orifice coefficient
$h$	Specific enthalpy	$J / kg$
$hp$	Primary side heat transfer coefficient in the simple heater model	$W / m^{2} - K$
$h_{tot}, H$	Total heat transfer coefficient	$W / m^{2} - K$
$H$	Height	$m$
$H$	Work	$W$
$I$	Moment of inertia	$kg - m^{2}$
$j$	Lowermost node in a region
$k$	Thermal conductivity	$W / m - K$
$k$	Valve spring constant	$kg / s^{2}$
$k_{p}$	Thermal conductivity of the primary side in the simple heater model	$W / m - K$
$K$	Loss constant
$L$	Element length, or distance	$m$
$L_{B} / D_{B}$	Effective length-to-diameter ratio per bend
$m, M$	Mass	$kg$
$n$	Index on the discretized time variable
$n$	Number of nodes in a region
$N_{B}$	Number of bends along a flow path
$Nu$	Nusselt number
$P,\ P^{*}$	Pressure	$Pa$
$POD$	Pitch-to-diameter ratio
$Pr$	Prandtl number
$q$	Heat flux	$J / s - m^{2}$
$Q$	Heat source	$J / s$
$Q$	Volumetric heat source	$W / m^{3}$
$Q$	Energy transfer rate	$W$
$r$	Radius	$m$
$r_{5}$	Two-phase multiplier
$R$	Thermal resistance	$K / W$
$R$	Loss factor
$Re$	Reynolds number
$s$	Distance	$m$
$s$	Specific entropy	$J / kg - K$
$sgn \left( j, l \right)$	+1 if the steady state flow in segment $j$ is entering volume $l$ -1 if the steady state flow in segment $j$ is leaving volume $l$
$t$	Time	$s$
$T$	Temperature	$K$
$TP$	Elevation of two-phase interface	$m$
$u, v$	Fluid velocity	$m / s$
$U_{pseu}$	Pseudo-heat conduction coefficient	$W / K$
$v$	Specific volume	$m^{3} / kg$
$V$	Volume	$m^{3}$
$V_{a},V_{b}$	Steam velocities relative to the blade and parallel to the blade motion at the blade entrance and exit, respectively	$m / s$
$V_{1}$	Absolute steam velocity at the blade entrance	$m / s$
$V_{2}$	Steam velocity relative to the blade at the blade entrance	$m / s$
$V_{3}$	Steam velocity relative to the blade at the blade exit	$m / s$
$V_{4}$	Absolute steam velocity at the blade exit	$m / s$
$w$	Mass flow rate	$kg / s$
$WR$	Wall resistance on water side
$WRNA$	Wall resistance on sodium side
$x$	Quality
$y$	Valve stem position	$m$
$z$	Spatial variable	$m$
$Z$	Spatial location, region length, or elevation of pipe center	$m$
$\Delta z$	$z_{0} - \ z_{I}$, the elevation difference between the outlet and the inlet of a flow element	$m$
$\alpha$	Void fraction
$\alpha$	Nozzle exit angle	$rad$
$\beta$	Volumetric quality
$\gamma$	Blade exit angle	$rad$
$\delta$	Thickness	$m$
$\varepsilon$	Element roughness	$m$
$\eta$	Efficiency
$\theta$	Angle of inclination with respect to the vertical
$\mu$	Dynamic viscosity	$Pa - s$
$v$	Specific volume	$m^{3} / kg$
$\rho$	Density	$kg / m^{3}$
$\tau$	Viscous stress tensor	$Pa$
$\tau$	Torque	$N - m$
$\varphi$	Valve characteristic
$\chi$	Quality
$\omega$	Rotor angular velocity	$rad / s$
Subscripts
$ACC$	Accumulated pressure at which value fully opens
$b$	Bottom
$B$	Blade
$BLD$	Blowdown pressure at which valve closes
$D$	Drain, or DNB
$E$	Exhaust
$f$	Liquid
$fg$	Vapor minus liquid
$g$	Vapor
$G$	Generator
$hf$	Location of hf
$hg$	Location of hg
$i$	Node number, region number, inside
$I, in$	Inlet
$j$	Segment number
$m$	Metal tube, or tube wall
$misc$	Miscellaneous
$M$	Moisture, or mid-wall
$nz$	Nozzle
$Na$	Sodium
$o$	Outside, theoretical
$O,out$	Outlet
$r$	Reference
$R$	Rotation
$s$	Sodium, shell side, steam drum
$S$	Surface
$sat$	Saturation
$SC$	Subcooled zone
$SG$	Steam generator
$SH$	Superheated zone
$t$	Top, tube side, total
$T$	Total, turbine
$TP$	Boiling zone
$u$	Upper
$w$	Water
$l$	Volume number
$\infty$	Ambient
Superscripts
$k,n$	Time step index
$n$	Normalized
$u$	Unnormalized
$-$	Isentropic quantity