WSRC-MS-98-00447
Page 1 of 8
PRODUCTION OF A HIGH-LEVEL WASTE GLASS
FROM HANFORD WASTE SAMPLES

Charles L. Crawford
Westinghouse Savannah
River Co.
Bldg. 773-A
Aiken, SC 29808
(803) 725-8049

Daro M. Ferrara
Westinghouse Savannah
River Co.
Bldg. 772-F
Aiken, SC 29808
(803) 952-4448

Bao C. Ha
Westinghouse Savannah
River Co.
Bldg. 773-A
Aiken, SC 29808
(803) 725-0972

Ned E. Bibler
Westinghouse Savannah
River Co.
Bldg. 773-A
Aiken, SC 29808
(803) 725-2313

I. INTRODUCTION

The HLW glass was produced from a
HLW sludge slurry (Envelope D Waste), eluate
waste streams containing high levels of Cs-137
and Tc-99, solids containing both Sr-90 and
transuranics (TRU), and glass-forming
chemicals. The eluates and Sr-90/TRU solids
were obtained from ion-exchange and
precipitation pretreatments, respectively, of other
Hanford supernate samples (Envelopes A, B and
C Waste). The glass was vitrified by mixing the
different waste streams with glass-forming
chemicals in platinum/gold crucibles and heating
the mixture to 1150 *C.
Resulting glass analyses indicated that
the HLW glass waste form composition was
close to the target composition. The targeted
waste loading of Envelope D sludge solids in the
HLW glass was 30.7 wt%, exclusive of Na and
Si oxides. Condensate samples from the off-gas
condenser and off-gas dry-ice trap indicated that
very little of the radionuclides were volatilized
during vitrification. Microstructure analysis of
the HLW glass using Scanning Electron
Microscopy (SEM) and Energy Dispersive X-
Ray Analysis (EDAX) showed what appeared to
be iron spinel in the HLW glass. Further X-Ray
Diffraction (XRD) analysis confirmed the
presence of nickel spinel trevorite (NiFe2O4).
These crystals did not degrade the leaching
characteristics of the glass. The HLW glass
waste form passed leach tests that included a
standard 90  C Product Consistency Test (PCT)
and a modified version of the United States
Environmental Protection Agency Toxicity
Characteristic Leaching Procedure (TCLP).

As part of the Tank Waste Remediation
System (TWRS), the United States Department
of Energy (DOE) issued a Request for Proposal
(RFP)' to vendors interested in building and
operating a privatized facility for immobilizing
radioactive waste currently being stored in tanks
at the DOE site in Hanford, Washington. British
Nuclear Fuels Limited, Incorporated (BNFL,
Inc.), responded to the RFP and was awarded a
contract to perform the initial phase of this
work.' BNFL has teamed with SAIC, Bechtel
National Inc., BNFL Engineering Ltd. (BEL),
GTS Duratek and the Vitreous State Laboratory
(VSL) at Catholic University to develop and
demonstrate technology needed to meet the
terms outlined in the TWRS RFP. In
collaboration with the BNFL team, the Savannah
River Technology Center (SRTC) was asked to
perform radioactive demonstrations with four
samples of the actual radioactive waste from
Hanford.
SRTC has produced and characterized
three Low-Activity (LAW) glasses and a single
High-Level Waste (HLW) glass from actual
radioactive Hanford waste samples. The three
waste samples used for the LAW glasses are
referred to as Envelopes A, B and C. The HLW
glass was produced from a mixture of the
following waste streams: (1) HLW sludge slurry
referred to as Envelope D from Hanford Tank
241-C-106,3 (2) eluate waste streams containing
high levels of Cs-137 and Tc-99 derived from
ion exchange treatment of Envelopes A,B and C,
(3) solids containing both Sr-90 and transuranics
(TRU) derived from precipitation treatment of
Envelope C, and (4) glass-forming chemicals.

ABSTRACT