METHODE POUR REUTILISER DU BETON CONTAMINE

METHOD FOR REUSE OF CONTAMINATED CONCRETE

Abrégé français

Méthode pour réduire au minimum les volumes de déchets provenant de la démolition d'installations radiologiques et (ou) chimiques en béton contaminé, grâce à des techniques permettant de séparer les fractions contaminées des fractions non contaminées et (ou) de réutiliser le béton contaminé pour la fabrication de contenants de stockage ou d'élimination des déchets. La démolition à l'explosif sert soit à éliminer sélectivement les couches de béton superficielles contaminées du béton sous-jacent non contaminé (là où la contamination est confinée aux couches de surface), ou, lorsque la contamination traverse toute l'épaisseur de béton, à réduire le béton contaminé en morceaux de taille appropriée pour servir comme agrégats industriels. Le reste de la structure de béton peut aussi être démoli à l'aide de techniques normalisées, si le béton sous-jacent n'est pas contaminé; les gravats résultants peuvent alors être recyclés ou éliminés. On peut, selon les besoins, faire passer les morceaux de béton dans un concasseur pour béton jusqu'à obtention de la taille d'agrégat appropriée. L'agrégat recyclé et de taille voulue est ensuite utilisé pour la production de contenants de stockage ou d'élimination, de compartiments, etc. pour matériaux et déchets nucléaires et (ou) dangereux, ce qui réduit le volume de déchets et les coûts résultant du démantèlement des installations nucléaires (ou d'unités chimiques de même type).

Abrégé anglais

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.

Revendications

- 7 -
What is claimed as invention is:
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

- 8 -
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.

Description

CA 0220~947 1997-0~-23
CASE 5804
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
-2- CASE 5804
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
CASE 5804
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
CASE 5804
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
CASE 5804
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
-6- CASE 5804
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.