The radial momentum operator, p_r is:
p_r Psi = 1/2r (dot(r_i,p_i)+dot(p_i,r_i)) Psi
in spherical coordinates this is:
p_r Psi= hb/ir d/dr (rPsi)
p_r^2 Psi = -hb^2/r d^2/dr^2 (rPsi)