The　nuclear-data　uncertainties　directly　impact　the　prediction　results　of　neutron-physics　calculations.　In　this　paper,　total　sensitivity　and　total　uncertainty　analysis　code,　named　as　UNICORN,　has　been　newly　developed,　applying　the　direct　numerical　perturbation　method　and　statistical　sampling　method.　A　multigroup　cross-section　perturbation　model　has　been　established,　which　can　perform　perturbations　to　the　microscopic　cross-section　library　both　for　the　integral　and　basic　types　of　cross　sections.　DRAGON　4.0　is　applied　to　carry　out　resonance　self-shielding　and　neutron-transport　calculations,　with　use　of　WTMSD-4　library.　For　verifications　of　UNICORN,　total　sensitivity　analyses　have　been　performed　to　the　TMI-1　and　PB-2　pin-cell　benchmarks,　both　by　UNICORN　and　TSUNAMI-ID.　And　the　total　relative　sensitivity　coefficients　by　UNICORN　agree　well　with　those　by　TSUNAMI-1D,　which　proves　the　multigroup　cross-section　perturbation　model　and　development　of　UNICORN　are　correct.　Based　on　verifications,　UNICORN　has　been　applied　to　perform　total　uncertainty　analyses　for　k,　and　two-group　macroscopic　constants　to　the　TMI-1　assembly　at　the　HZP　and　HFP　conditions.　And　it　can　be　observed　that　the　uncertainties　at　HFP　are　a　little　larger　than　those　at　HZP.　And　the　relative　uncertainty　of　k,　can　be　about　4.7%o;　relative　uncertainties　of　the　macroscopic　constants　vary　from　2.8%o　(for　the　Σt.2)　to　11.8%o　(for　the　Σ5t.2).