The Bruckner orbital based CCD(T) approach is not available in NWChem.
For singlet organic biradicals you may want to use NWChem implementations of the
multi-reference CC methods (Brilloiun-Wigner/Mukherjee). For biradicals these methods
works pretty good and are not that expensive - usually 2 active electrons in 2 active orbitals
provide a reasonable model space.
Best,
Karol