The Mn-Mo-Ni/Linde 80 submerged-arc weld metals are characterized as being highly sensitive to neutron embrittlement based on their chemical composition. The weld metals fabricated from Weld Wire 72105 contain moderate amounts of nickel but relatively high copper contents as a result of the copper coating applied to the weld wire to inhibit corrosion and improve electrical contact. Welds fabricated from Weld Wire 72105 have abnormally high measured unirradiated Charpy transition temperature properties and low Charpy upper-shelf energies. The irradiation response of these welds is contrary to that which would normally be expected based on measured unirradiated properties and chemical composition. The irradiated Charpy 30 ft-lb (41 J) temperature data appear to stabilize at a fluence of about 8 × 1018 n/cm2 with no further degradation at higher fluences based on data to fluences up to 1.5 × 1019 n/cm2. The characteristic does not appear to occur for the irradiated Charpy upper-shelf energy data. These data show that welds fabricated with Weld Wire 72105 do not have the neutron radiation sensitivity that would be expected based on the normal criterion such as Regulatory Guide 1.99, Revision 2. Sufficient irradiation data exist to establish an embrittlement correlation specifically for the weld metals fabricated with Weld Wire 72105.