  In noncentrosymmetric superconductors (NCSs), the inversion symmetry (IS) is
most commonly broken by an antisymmetric spin-orbit coupling (SOC) removing the
spin degeneracy and splitting the Fermi surface (FS) into two branches. A two
component condensate is then produced with a doublet pair potential mixing an
even singlet and an odd triplet. When the triplet and the singlet strengths are
comparable, the pair potential can have rich nodes. The angular line nodes
(ALNs) are associated with strong anisotropy and they are widely studied in the
literature. When the anisotropy is not strong, they can be replaced by other
types of nodes in closed or open forms affecting the low temperature
properties.
  Here, we focus on the weakly anisotropic case and the line nodes in the
superconducting plane which become circular in the limit of full isotropy. We
study the topology of these radial line nodes (RLNs) and show that it is
characterized by the $Z_2$ classification similar to the Quantum-Spin-Hall
Insulators. From the thermodynamical perspective, the RLNs cause, even in the
topological phases, an exponentially suppressed low temperature behaviour which
can be mistaken by nodeless s-wave pairing, thus, providing an explanation to a
number of recent experiments with contraversial pairing symmetries. In the rare
case when the RLN is on the Fermi surface, the exponential suppression is
replaced by a linear temperature dependence. The RLNs are difficult to detect,
and for this reason, they may have escaped experimental attention. We
demonstrate that Andreev conductance measurements with clean interfaces can
efficiently probe the weakly anisotropic samples where the RLNs are expected to
be found.
