Abstract: A nickel-based alloy and welding processes and consumables that use the alloy as a weld filler metal to fabricate, weld overlay, and repair components, including components of nuclear power plant reactors that contact the hot coolant water of the reactor. The nickel-based alloy consists of, by weight, 26 to about 30% chromium, 2 to about 4% iron, 2 to about 4% manganese, 2 to about 3% niobium, 1 to about 3% molybdenum, not more than 0.6% titanium, not more than 0.03% carbon, not more than 0.05% nitrogen, not more than 0.6% aluminum, not more than 0.5% silicon, not more than 0.01% copper, not more than 0.02% phosphorus, not more than 0.01% sulfur, with the balance nickel and incidental impurities.