Environmental Engineering Reference
In-Depth Information
quantities of transuranic* (TRU) waste, which possessed greater radioactive emis-
sions from alpha-emitting sources. TRU waste is generated by plutonium-based DOE
nuclear defense activities and is disposed of at the Waste Isolation Pilot Plant (WIPP)
in Carlsbad, NM. Little work in the field of waste stabilization had been done and
reported on the TRU waste.
In 1983 LANL chose to investigate a product manufactured by the United States
Gypsum Company called Envirostone™** Gypsum Cement
(hereafter referred to
as Envirostone). The data available in 1983 was almost exclusively contained in a
technical marketing document issued by U.S. Gypsum in 1982.
1
Envirostone is a
finely ground, nonflammable powder composed of calcium sulfate hemihydrate,
water-soluble melamine formaldehyde resin, and a small amount of ammonium
chloride, which serves as a cross-linking agent to facilitate resin curing.
2
Envirostone
is presented as a low-level radioactive waste (LLRW) solidification medium capable
of solidifying a variety of waste streams associated with nuclear utilities operations
for which portland cement has experienced difficulty in solidifying. The waste
streams of primary interest were boric acid evaporator bottoms and ion exchange
resins, as well as nonpolar organic liquids, such as waste oils, when used in con-
junction with Envirostone Emulsifier. Brookhaven National Laboratory (BNL) inde-
pendently confirmed the compatibility of Envirostone with emulsified oil.
3
The
Envirostone product solidifies acidic waste best,
1
unlike portland cement that requires
a basic pH for solidification. The U.S. Gypsum report preceded the issuance of 10
CFR Part 61.56, which detailed the NRC's stricter standards for waste form perfor-
mance.
4
However, satisfactory performance was demonstrated in the 1980-1983 test
period using the current versions of the following standards:
1
•
Leach resistance for
137
Cs,
144
Ce,
60
Co, and
85
Sr according to ANSI/ANS-
16.1-2003
5
•
Compressive strength according to ASTM C472
6
and ASTM D560
7
•
Water impingement and 8-month water immersion testing
Favorable results were reported by U.S. Gypsum with actual wastes from the
Kewaunee Nuclear Station, the Ginna Nuclear Station, and Lawrence Livermore
National Laboratory (LLNL).
1
Envirostone™ solidified waste forms were accepted
by the state agencies and operators of the three commercial LLRW disposal sites.
1
6.4.2
U
SE
OF
E
NVIROSTONE
™
AT
L
OS
A
LAMOS
N
ATIONAL
L
ABORATORY
LANL was interested in Envirostone™ as an alternative to portland cement for
several TRU waste streams generated at the TA-55 Plutonium Facility. TRU waste
form performance requirements are defined in the Waste Isolation Pilot Plant Waste
Acceptance Criteria (WIPP-WAC).
8
Envirostone™ had not yet been evaluated
* TRU waste is any waste that contains alpha-emitting radionuclides of atomic number greater than 92
with a half-life exceeding 20 years and a specific activity of greater than 100 nCi/g.
** Envirostone™ is a registered trademark of United States Gypsum Company, Chicago.
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