Radioactive waste repository when contacted by water provides borates that absorb neutrons

1. A repository for storing radioactive material adjacent to water, the repository comprising:

a container for holding the radioactive material; and

a sub-criticality controller for protecting the radioactive material from reaching a criticality from contact with the water;

wherein the sub-criticality controller includes a metallic composition having a metal component and a borate component bonded to the metal component; and

wherein the metallic composition forms a second borate from the borate component reacting with the metal component when the metallic composition contacts the water.

2. The repository of claim 1 , wherein the second borate is selected from the group consisting of lead borate, cadmium borate, zinc borate, manganese borate, iron borate, cobalt borate, nickel borate, copper borate, tin borate, bismuth borate, antimony borate, calcium borate, magnesium borate, lead metaborate hydrate, cadmium metaborate, zinc metaborate, manganese metaborate, iron metaborate, cobalt metaborate, nickel metaborate, copper metaborate, tin metaborate, bismuth metaborate, and antimony metaborate.

3. The repository of claim 1 , wherein

the borate component includes sodium tetraborate hydrate; and

the metal component includes a metal-bearing compound.

4. The repository of claim 3 , wherein the metal-bearing compound is selected from the group consisting of a lead-bearing compound, a cadmium-bearing compound, a zinc-bearing compound, a manganese-bearing compound, an iron-bearing compound, a cobalt-bearing compound, a nickel-bearing compound, a copper-bearing compound, a tin-bearing compound, an antimony-bearing compound, a bismuth-bearing compound, a calcium-bearing compound, and a magnesium-bearing compound.

5. The repository of claim 1 , wherein the metal component includes a metal oxide comprising a metal, and the borate component comprises boric acid.

6. The repository of claim 5 , wherein the metal is selected from the group consisting of lead, cadmium, zinc, manganese, iron, cobalt, nickel, copper, tin, antimony, bismuth, calcium, and magnesium.

7. The repository of claim 1 , wherein the metal component includes a metal hydroxide for providing a metal, and the borate material include boric acid.

8. The repository of claim 7 , wherein the metal is selected from the group consisting of lead, cadmium, zinc, manganese, iron, cobalt, nickel, copper, tin, antimony, bismuth, calcium, and magnesium.

9. The repository of claim 1 , wherein the metal component includes a cation selected from the group consisting of a divalent cation, a trivalent cation, a mixture of divalent cations, a mixture of trivalent cations, and a mixture of both divalent and trivalent cations.

10. The repository of claim 1 , wherein the sub-criticality controller is in the container.