anchor.diff:  END SUBROUTINE th_trans
   
   
  -
  -
   SUBROUTINE th_upd(xpline)
   
   !
  
positive.code:             a(nt-1) = -xa
              b(nt-1) =  xa + xc
              c(nt-1) = -xc
              d(nt-1) = pdens * 0.5 * (rf**2 - rpos(nt-2)**2)
  
              ! For nt [GAP-CLADDING INTERFACE]
              tem = 0.5 * (tfm(xyz(i,j,k),nt) + tfm(xyz(i,j,k),nt+1))
              kt = getkc(tem)      ! For cladding
              xa = xc
              xc = kt * rpos(nt) / rdel(nt)
              a(nt) = -xa
  
negative.code: 
  DOUBLE PRECISION :: pdens      ! power densisty  (W/m3)
  DOUBLE PRECISION :: enti       ! Coolant inlet enthalpy
  DOUBLE PRECISION, DIMENSION(nxx, nyy) :: entm
  DOUBLE PRECISION :: cpline     ! Coolant Linear power densisty (W/m)
  DOUBLE PRECISION :: Pr, kv, tcon ! Coolant Prandtl Number, Kinematic viscosity, and thermal conductivity
  
  