Adding gap width mult threshold

          always captured in the model.  Not modeling them will save some computational time.

       sym_opt (int): Enter either 1 for full core geometry or 4 for quarter symmetry geometry.

       gapWidthMultNarrow (float): Global multiplier that will be applied to all gaps with a nominal width

          less than or equal to 10 mm (typically intra-assembly gaps)

          less than or equal to gapWidthMultThreshold. Useful for applying a multiplier specifically to

          intra-assembly gaps (which are typically < 0.01 m)

       gapWidthMultWide (float): Global multiplier that will be applied to all gaps with a nominal width

          greater than 10 mm (typically inter-assembly gaps)    

          greater than gapWidthMultThreshold. Useful for applying a multiplier specifically to inter-assembly

          gaps (which are typically > 0.01 m)

       gapWidthMultThreshold (float): Threshold for applying narrow or wide gap width multipliers [m]. Each gap with

          a nominal width less than gapWidthMultThreshold will be multiplied by gapWidthMultNarrow, otherwise

          it will be multiplied by gapWidthMultWide.  Defaults to 0.01 m, which for typical 17x17 PWR fuel should

          successfully distinguish between all intra- and inter-assembly gaps.

       gapLengthMult (float): Global multiplier that will be applied to all gap lengths in the model.

    """

    def __init__(me, model, coreMap, assemMaps, pitch, dz, solidGeoms, startChanIndex=1, assemPitch=None,

                 baffleGap=0.0, sectionID=1, symOpt=1, assemLosses=None, assemLossLevels=None,

                 assemGridBlockageRatios=None, assemGridEnhancementCoeffs=None, rodDomains=None, modelGuideTubes=False, sym_opt=1,

                 gapWidthMultNarrow=1.0, gapWidthMultWide=1.0, gapLengthMult=1.0):

                 gapWidthMultNarrow=1.0, gapWidthMultWide=1.0, gapLengthMult=1.0, gapWidthMultThreshold=0.01):

        assert(isinstance(model, Model.Model))

        assert(len(coreMap) > 0)

        assert(utils.isArraySquare(coreMap))

                    if southGaps:

                        gaps = gaps + southGaps

                    for gap in gaps:

                        if gap.width > 0.01:

                        if gap.width > gapWidthMultThreshold:

                            width = gap.width * gapWidthMultWide

                        else:

                            width = gap.width * gapWidthMultNarrow