2.8.2.16. Block 65 — FUELIN — Channel-Dependent Fuel Input

FSPEC

1

Fuel-pin failure criterion, threshold value. IERSTP

(See also FMELTM and PCFAIL).

See MFAIL.

FMELTM

2

The minimum fuel melt fraction that must exist at the failure node before PLUTO2 or LEVITATE is allowed to be called.

Suggested value: 0.2 (must be input > 0).

DENS

3

kg/m^3

Liquid cladding density at the liquidus.

AE

4

1/K

Coefficient of linear expansion of solid cladding (=1/3 volume coefficient).

RHOCD

5

1/K

Volumetric coefficient of expansion for liquid cladding.

VISMC

6

Pa-s

Viscosity of cladding at liquidus temperature. At higher temperatures,

viscosity= VISMC*EXP( AVISC / TELIQ - AVISC /T).

VISTR

7

Pa-s

Viscosity of cladding at solidus temperature. Between solidus and liquidus,

viscosity=(VISTR-VISMC)* (1-FMELTC)** XVISC + VISMC

where FMELTC is the melt fraction.

VISSC

8

Pa-s

Viscosity of refrozen cladding. This is used as viscosity below solidus.

XVISC

9

Exponent in viscosity equation.

CLADFR

10

Moody friction factor for the molten cladding during turbulent cladding flow over the fuel rod.

REBRK

11

Laminar to turbulent transition Reynolds number for molten cladding flow.

GMULTF

12

Constants in molten cladding and sodium vapor two-phase friction multiplier.

Multiplier = CHOR*(1.0+GMULTF*(1.0-MAX(ALPH, ALPHCR )))

where ALPH is void fraction. The incoherence (time delay) factor is:

CHOR=MAX(0.01,MIN(1.0,(FPS/ FPS0 )** EXPFPS ))

where FPS is the time in full-power seconds since cladding first moved in the channel.

ALPHCR

13

See GMULTF.

FPS0

14

See GMULTF.

EXPFPS

15

See GMULTF.

AMELT

16

Not currently used.

CLSTHR

17

Multiplier for frozen cladding-structure heat transfer.

Suggested value: 1.0.

FRACPD

18

Not currently used.

PCFAIL

19

Pa

Pin cavity pressure at pin failure time. Only necessary if the transient DEFORM calculation is not used (ISSFU2 .NE.1) or if CLAP preceded LEVITATE in this channel. May also be useful for overriding the DEFORM calculated cavity pressure for parametric studies. For PCFAIL < 1, the DEFORM calculated cavity pressure is used in PLUTO and LEVITATE. This is the recommended option when it can be used.

AVISC

20

K

Constant in viscosity equation. (See VISMC).

CPC

21

J/kg-K

Specific heat capacity of molten cladding at the liquidus temperature.

FPINAC

22

Areal fraction of fuel, with enthalpy exceeding the melting threshold of at least FNMELT of the heat of fusion, required to initiate PINACLE ; i.e. for in-pin pre-failure fuel motion to begin. See FNMELT and CPINAC .

Recommended value: 2 radial nodes.

CPINAC

23

Also, at least 3 contiguous axial nodes must satisfy the condition: Molten fuel fraction > FPINAC x CPINAC in order to initiate PINACLE. Recommended value: 0.5.

RHOREF

24

Not currently used.

WUREF

25

Fabricated uranium weight fraction in the metal fuel in the SSCOMP model (IFUELO = 1).

WPUREF

26

Fabricated plutonium weight fraction in the metal fuel in the SSCOMP model (IFUELO = 1).

WZRREF

27

Fabricated zirconium weight fraction in the metal fuel in the SSCOMP model (IFUELO = 1).

DFUELX

28-51

Not currently used.

FUSLDT

52

m

Maximum axial displacement of the upper fuel blanket or/and sodium slug above the fuel active top.

FUSLMA

53

kg/pin

Total mass of the upper fuel blanket or/and sodium slug above fuel pin top.

BURNFU

54

at\%

Axially averaged fuel pin burnup for metal fuel pins used in the SSCOMP model (IFUELO = 1). Also used for IFUELM = 2.

= 0, FPDAYS and FLTPOW used to calculate cladding fluence.

> 0, BURNFU determines cladding fluence.

XPUZR

55-198

Post-zone formation plutonium and Zirconium weight fractions in the central zone, followed by those in the middle zone and those in the outer zone.

Not currently used.

GASRTM

199

Not currently used.

TIRRFU

200

K

Cladding steady state irradiation temperature at the top of the fuel region for metal fueled pins. Used in life fraction calculation.

≤ 0, Maximum temperature during steady state at each axial node used.

> 0, And ISSFUE = 0, value applied to each axial node

DFUELI

201-300

Not currently used.