CA2205947A1

CA2205947A1 - Method for reuse of contaminated concrete

Info

Publication number: CA2205947A1
Application number: CA 2205947
Authority: CA
Inventors: John Bernard Meyers; Timothy Carter Marks; Charles Paul Pietsch; Richard Seymour Kingsley
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1996-05-31
Filing date: 1997-05-23
Publication date: 1997-11-30
Also published as: RU2144707C1

Abstract

A method for minimizing waste volumes from the demolition of radiologically and/or chemically contaminated concrete facilities by using engineering techniques to separate contaminated from uncontaminated fractions and/or by reusing the contaminated concrete for manufacture of waste storage or disposal containers. Explosive demolition is used to either selectively remove contaminated surface layers of concrete from underlying uncontaminated concrete (where the contamination is confined to the surface layers), or, where the contamination is throughout the concrete, to reduce contaminated concrete into pieces of an appropriate size for use as manufacturing aggregate.
The balance of the concrete structure can alternatively be demolished using standard techniques if underlying concrete is clean, and the resulting rubble free released for recycle or disposal. When required, the concrete pieces are processed through a concrete crusher until the appropriate aggregate size is achieved. The recycled and previously regulated aggregate is then used in manufacturing of storage or disposal containers, cells, etc. for nuclear and/or hazardous waste and material, thus reducing waste volumes and costs resulting from the decommissioning of nuclear (or similar chemical processing) facilities.

Description

CA 0220~947 1997-0~-23 METHOD FOR REUSE OF CONT~MTN~TED CONCRETE

BACKGROUND OF THE INVENTION
1. Field of the Invention The invention is generally related to a method for the demolition of radiologically or hazardous chemically contaminated buildings constructed from concrete or other cementatious materials, the waste management (minimization) of the contaminated materials produced, and the beneficial unregulated recycle and reuse of those volumes of contaminated materials actually produced by using the previously regulated concrete rubble as aggregate or cement in the construction of waste disposal containers.

2. General Background In the nuclear industry, nuclear waste and nuclear materials are being shipped, stored, and/or disposed in concrete containers and cells. These containers and cells are made with concrete produced with clean aggregate. In another aspect of the nuclear industry, radiologically contaminated buildings and containment structures are being demolished, resulting in large volumes of contaminated materials that must be safely disposed. These materials include radiologically and/or hazardous chemically contaminated concrete. These waste materials are disposed at federal or state regulated sites. Recent state regulatory initiatives at one such current disposal site (in South Carolina) require that such radiologically contaminated building rubble and similar wastes be buried in concrete burial boxes or vaults.
These aspects of the nuclear industry reveal three areas of CA 0220~947 1997-0~-23 need that have not been adequately addressed. One is the unnecessary generation of regulated waste by the use of conventional demolition techniques. Most nuclear materials processing facilities and nuclear power reactors are thick-walled structures constructed of thousands of cubic yards of high-density, reinforced concrete for structural strength and radiation shielding. Depending on the type of facility and process involved, the radiation and/or chemical contamination is frequently restricted to the first few inches of the concrete surface. In such cases, the use of conventional demolition techniques results in the cross-contamination of the previously clean concrete below the surface layers, thus vastly increasing the volume of regulated wastes needing disposal in licensed facilities.
A second area of need relates to the high cost and logistical difficulty of disposing of radiologically and/or chemically contaminated concrete. Over the next twenty years, nearly all of the existing nuclear power stations in the United States are scheduled to be decommissioned and (eventually) demolished. A similar situation exists within the Department of Energy's nuclear wéapons complex, where production facilities have been almost all permanently closed. Adequate disposal capacity for the large volumes of concrete rubble and other wastes which will likely be generated from decommissioning these facilities does not currently exist. Nor is it likely to be developed in the foreseeable future because of difficulties in siting and licensing new disposal facilities. Even if adequate CA 0220~947 1997-0~-23 capacity does become available, the rapidly escalating costs of burial (which have doubled for some types of waste over the past year) may make disposal costs prohibitive.
The third area of need relates to the high costs (and unnecessary waste) of building new concrete storage and disposal containers using clean, uncontaminated aggregate, when the demolition rubble itself represents a source of potentially useful aggregate.
SUMMARY OF THE INVENTION
The invention addresses the above needs. What is provided is a demolition methodology for radiologically and/or chemically contaminated concrete structures whereby volumes of regulated wastes requiring disposal are minimized by: 1) the use of engineering techniques during the demolition process to segregate the clean from the contaminated waste fraction, and/or 2) the re-use of the contaminated concrete in the manufacture of waste storage or disposal containers. Explosive demolition is used to either selectively remove contaminated surface layers of concrete from underlying uncontaminated concrete (where the contamination is confined to the surface layers), or, where the contamination is throughout the concrete, to reduce contaminated concrete into pieces of an appropriate size for use as aggregate. If further size reduction is required for use as aggregate, the concrete pieces are processed through a concrete crusher until the appropriate size is achieved. Once released for use, the recycled aggregate is shipped to a concrete manufacturing plant where it is used to produce concrete for the manufacture of waste CA 0220~947 1997-0~-23 storage/disposal containers, vaults, or cells. Wastes stored/disposed in these containers would include radiological or hazardous chemically contaminated waste, contaminated building rubble, contaminated processing equipment, and other similar debris. In addition, any clean uncontaminated concrete itself resulting from the demolition of nuclear facilities can be reused for the manufacture of these containers by heating the crushed clean concrete in a conventional recycle kiln.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Those portions of an existing nuclear facility or similar facilities, such as a chemical processing plant, which are constructed from concrete or other cementatious material are demolished using engineered explosions or controlled demolition methods to either selectively delaminate the contaminated surface layers from uncontaminated concrete below (where the contamination is confined to the surface layers), or, where the contamination is throughout the concrete, to reduce the resulting rubble to a size appropriate for use as a manufacturing aggregate. The use of explosive demolition techniques reduces the potential for personnel exposure to radiation or other hazardous chemicals, consistent with Nuclear Regulatory Commission, Environmental Protection Agency and Department of Energy "As Low As Reasonably Achievable (ALARA)" concepts, as well as achieving the demolition of the structures in the safest manner possible.
If the concrete below the surface layers is uncontaminated, following removal of the delaminated (contaminated surface) CA 0220~947 1997-0~-23 layers, the remainder of the concrete structure can alternatively be demolished using standard construction techniques, and the resulting rubble free released for recycling or disposal. At any rate, the reduced contaminated concrete material is then measured to determine if it will pass through the appropriate sieves, for use as manufacturing aggregate, in a concrete plant. If the concrete requires further size reduction, it is then processed by use of a concrete crusher to insure that the appropriate manufacturing aggregate size is achieved. This may be done at the site by providing a mobile concrete crusher.
The aggregate is then statistically sampled and analyzed for radionuclide and/or hazardous chemical content to insure that the rubble meets both plant requirements for aggregate use (principally physical size and chemical composition) and burial site license requirements for use as storage or disposal containers/vaults/cells.
The aggregate is then used in the manufacture of storage or disposal containers, vaults, cells, etc. for a wide variety of radiological, hazardous chemical, or "mixed wastes" produced during the decontamination and decommissioning of nuclear facilities and/or similar facilities such as chemical processing plants or waste disposal facilities.
It should be understood that the contaminated aggregate may also be used in the manufacture of other concrete structures such as roads, radiation shielding, etc.
Because many varying and differing embodiments may be made within the scope of the inventive concept herein taught and CA 0220~947 1997-0~-23 because many modifications may be made in the embodiment herein detailed in accordance with the descriptive requirement of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.

Claims

1. A method for minimizing waste volumes from the demolition of radiologically and/or chemically contaminated concrete facilities, comprising:
a. demolishing the facility to reduce the size of individual pieces of the contaminated concrete to a size appropriate for reuse as manufacturing aggregate;
b. statistically sampling and analyzing the aggregate to insure suitability for use as manufacturing aggregate; and c. utilizing the aggregate in the manufacture of storage or disposal containers for nuclear and/or hazardous chemical waste and material.

2. The method of claim 1, wherein engineered explosions are used in the selective removal of the contaminated concrete.

3. The method of claim 1, further comprising using a crusher to insure that the contaminated concrete is reduced to an appropriate aggregate size.

4. The method of claim 1, wherein the aggregate is utilized in the manufacture of concrete structures other than storage disposal containers.

5. A method for minimizing waste volumes from the demolition of radiologically and/or chemically contaminated concrete facilities, comprising:
a. demolishing the facility to reduce the size of individual pieces of the contaminated concrete for reuse as manufacturing aggregate;
b. processing the reduced concrete as required to insure reduction to an appropriate size for use as aggregate;
c. statistically sampling and analyzing the aggregate to insure suitability for use as manufacturing aggregate; and d. utilizing the aggregate in the manufacture of storage/disposal containers for nuclear and/or hazardous chemical waste and material.

6. The method of claim 5, wherein the aggregate is utilized in the manufacture of concrete structures other than storage or disposal containers.

7. The method of claim 5, wherein engineered explosions are used in the selective removal of the contaminated concrete.

8. The method of claim 5, wherein controlled demolition methods are used in the selective removal of the contaminated concrete.