AMBIENT TEMPERATURE DECONTAMINATION OF NUCLEAR POWER PLANT COMPONENT SURFACES CONTAINING RADIONUCLIDES IN A METAL OXIDE

• US 20150117587A1
• Filed: 10/29/2013
• Published: 04/30/2015
• Est. Priority Date: 10/29/2013
• Status: Active Grant

• Current Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Original Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Inventors: CRYTZER, KURTIS R., Ikeda, Lauren R., Vitale, Nicole D.
• Granted Patent: US 9,793,018 B2
• Time in Patent Office: Days
• US Class Current: 376/306
• CPC Class Codes: G21C 17/0225 Chemical surface treatment, e.g. corrosion corrosion prevention in presence of water from scale removal or by modification of the properties of the liquid C02F5/00; inhibiting corrosion by adding corrosion inhibitors C23F11/00
• CPC Class Codes: G21C 19/28 Arrangements for introducing fluent material into the reactor core; Arrangements for removing fluent material from the reactor core pumping coolant G21D
• CPC Class Codes: G21C 19/307 specially adapted for liquids decontamination of liquids G21F9/04
• CPC Class Codes: G21F 9/004 of metallic surfaces
• CPC Class Codes: G21F 9/30 Processing separating different isotopes of the same chemical element B01D59/00
• CPC Class Codes: Y02E 30/30 Nuclear fission reactors

Abstract

This invention generally concerns radioactive decontamination of deposits on components in a nuclear power plant and is specifically concerned with improved systems and methods for disrupting, dissolving, removing and reducing at ambient temperature radionuclides formed on the primary side surfaces of components in a pressurized water reactor and the internal components of a boiling water reactor. The methods include identifying the structure, taking the structure out of operational service, contacting the structure with an aqueous solution (e.g., a recirculating flow or static immersion), and adding an effective amount of elemental metal in solid form to the aqueous solution.

Claims

1. A method for at least partially disrupting or removing radioactive deposits formed on a surface of a structure in a nuclear water reactor, comprising:

identifying the structure;

taking the structure out of operational service;

contacting the surface of the structure with an aqueous solution; and

adding an effective amount of an elemental metal in solid form to the aqueous solution,

wherein the method is conducted at ambient temperature.

2. The method of claim 1, wherein radioactive deposits include one or more materials selected from the group consisting of radionuclides, oxide scale and corrosion products.

3. The method of claim 1, wherein the elemental metal is selected from the group consisting of metals with standard electrochemical potentials anodic to low alloy steel.

4. The method of claim 3, wherein the electrochemical potential of the elemental metal is more active than the potential of low alloy steel in the galvanic series of metals and alloys.

5. The method of claim 1, wherein the elemental metal is selected from the group consisting of zinc, aluminum, magnesium, beryllium, lithium, iron and mixtures thereof.

6. The method of claim 1, wherein the elemental metal is zinc.

7. The method of claim 1, wherein the elemental metal is in a form selected from the group consisting of slab, granular, powder, colloidal, and combinations thereof.

8. The method of claim 7, wherein the elemental metal is in colloidal form.

9. The method of claim 8, wherein the colloidal form contains particles selected from the group consisting of micron-sized particles, nano-sized particles and combinations thereof.

10. The method of claim 1, further comprising adding to the aqueous solution a material selected from the group consisting of sequestering agent, chelating agent and mixtures thereof.

11. The method of claim 10, further comprising adding a dispersant to the aqueous solution.

12. The method of claim 1, further comprising adding to the aqueous solution a material selected from the group consisting of an oxidizing agent, reducing agent and mixtures thereof.

13. The method of claim 1, wherein the elemental metal is present in an amount from about 0.001 M to about 2 M based on volume of the aqueous solution.

14. The method of claim 1, wherein the aqueous solution has a pH in a range from about 3.0 to about 13.

15. The method of claim 1, wherein the nuclear water reactor is in a condition selected from the group consisting of layup and shutdown.

16. The method of claim 1, wherein contacting comprises subjecting the surface of the structure to a technique selected from the group consisting of a recirculating flow of the aqueous solution and a static immersion of the aqueous solution.

17. The method of claim 1, further comprising:

disassociating metal ions from the radioactive deposits;

precipitating the metal ions to form a precipitate; and

removing the precipitate by employing a process selected from the group consisting of filtration, ion exchange and reverse osmosis.

18. The method of claim 1, further comprising at least one of purifying the disrupted and radioactive deposits, transferring said deposits to a containment sump, adding said deposits to a radioactive waste system and transporting said deposits to a location remote from the nuclear water reactor.

19. A composition effective to at least partially disrupt and dissolve radioactive deposits formed on a surface of a structure in a nuclear water reactor when the composition is in contact with the surface of the structure during non-operational conditions, the composition comprising:

an aqueous component; and

an elemental metal component in a solid form,

wherein the composition is effective to disassociate a metal ion from an oxide lattice of the radioactive deposits.

20. The composition of claim 19, wherein the elemental metal is selected from the group consisting of metals with standard electrochemical potentials anodic to low alloy steel.