• successfully vitrifies a range of glass-waste simulant formulations and

• provides additional data needed to refine a preliminary full scale RIC AVS design that is capable of meeting the performance requirements identified by DOE's Office of Environment Management Tanks Focus Area (TFA).

BREAKTHROUGHS The Exploratory Development Stage of the RIC AVS research and development project has resulted in significant achievements that commend a change in course for DOE's high-level waste vitrification programs. HIGH WASTE LOADINGS Waste loading of 80% in the glass has been achieved. This compares with a maximum safe loading percentage of about 25% using conventional melters. The RIC AVS higher waste loadings in the disposal canister will reduce the number of disposal canisters that would otherwise be created by the traditional melter technology by a factor of 2 or more. This reduction is projected to save billions of dollars in DOE defense disposal costs.

Bench-Scale Laboratory Apparatus for Testing the RIC AVS Concept to 1500°C (2732°F)

 

DOE defense disposal costs are currently estimated to be 25% of the $49 billion Yucca Mountain project. If DOE will require less than 25% of the repository, commensurate savings will reduce DOE's contribution to the civilian waste repository. FASTER CLEANUP The RIC AVS facility enables a high-level waste vitrification campaign at Hanford to be completed in 12 years rather than in the 30 years currently anticipated under the privatization contract. Design of a relatively low capital cost facility is in progress. This facility will significantly reduce the need for costly construction and subsequent decontamination and decommissioning costs associated with the centralized melter concept.

Conceptual View of the RIC AVS Operating Facility Showing the Bridge Crane Transporting an AVS Module to a Fill and Melt Station. Facility Operating Rate = 4 Modules per Day.

• SAVINGS

RIC AVS product glass is projected to cost about one-half the cost of the product glass made with traditional melter technology. The RIC AVS cost in dollars per kilogram of high-level waste vitrified is $459. This compares to $1,200 for Hanford and $2,400 for the Defense Waste Processing Facility at Savannah River. The 10 million kilograms of high-level waste at Hanford results in savings of $7.4 billion.

The capability to accept caustic waste as a feed to the RIC AVS module will substantially reduce or eliminate pre-treatment neutralization steps, which are now required using conventional melters. Testing was conducted with feed having a pH=13.4.

The RIC AVS technology has the capability to accept widely varying chemical compositions as input to the RIC AVS disposable vitrifier. The waste feed envelope for the RIC AVS technology is broader than the relatively stringent HLW flow sheet envelope required to preserve the operating capability of traditional melters.

The following table shows the parameters of the testing program involving the percentage waste loading, the analytically verified waste loading, and the pH of the sludge used.

RIC AVS Measured Waste Loadings and Simulant pH

Test	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16
%W	35	35	35	35	100	35	70	35	45	70	70	67	42	72	78	78
%W tstd						37-40	65-70	37-39	43-47	71-73	50-51	57-61		65-71		74-83
pH											7-8	8.75	8.70	8.52	8.41	13.5

% W: estimated percentage of waste in the melt determined from the weights of dried sludges prior to melting.

% W tstd : measured percentage of waste in the melt determined from post vitrification chemical analyses of the vitrified mixtures.

The chart on the next page graphically compares the results of leach testing performed by the Diagnostic Instrumentation and Analysis Laboratory at Mississippi State University. The two taller columns for each element shown are the leaching results in parts per million for two Environmental Assessment, or EA Glasses. The EA Glass is the reference glass. As can be seen, the RIC AVS glasses were far more leach resistant than the reference glasses in leachability results.

A diverse waste chemical variability will be permitted using the RIC AVS technology. This means that the RIC AVS technology minimizes the need for blending and pretreatment requirements, with consequent multi-billion dollar savings for DOE in the avoidance of costly and complicated blending and pretreatment operations. In addition, the RIC AVS has advantages in the avoidance of penalty payments to the vitrification contractor for any delays in delivering the waste stream, which is required to meet contractual commitments.

RELIABILITY

The RIC AVS will have greater operational reliability than traditional melters because the potential for a single point of failure that would cause a shutdown in operations is eliminated. Using the traditional melter technology, an entire vitrification campaign will be shut down should its single centralized melter fail. The envisioned RIC AVS Hanford facility processes twelve separate canisters acting as individual melters operating in parallel. A failure would only affect a single canister and would have minimal impact on the vitrification campaign.

 

ENVIRONMENTAL ENHANCEMENT

The RIC AVS technology will have less negative environmental impact than the traditional melter technology. Because the radioactive footprint of the RIC AVS facility is smaller, it poses less environmental burden from operations and decontamination and decommissioning.
Additionally, the final melting process occurs in the final disposal container and completely avoids the well-known and historically problematic process of pouring HLW melted glass into disposal canisters. And finally, the inner graphite crucible of the RIC AVS forms a high integrity second container to provide environmental containment over geologic periods, a feature absent from current designs.
	AVS Module Depicted in one of the RIC AVS Facility's Twelve Lower-Level Fill and Melt Stations.

SAFETY

The RIC AVS technology will be safer than traditional melter technology because less radioactive contamination and less need for repair work in radioactively contaminated areas will impose a lower radiation burden on workers. Most of the vitrification accidents in the past 20 years have been associated with glass pouring and/or long-term deterioration of the melter. The RIC AVS is not subject to these problems, because no pouring of molten radioactive glass occurs.

SYSTEM DESCRIPTION

The Radioactive Isolation Consortium's (RIC) Advanced Vitrification System (RIC AVS) is a new high-level waste (HLW) vitrification technology in which HLW/frit mixtures are directly melted inside final disposal modules, which, after cooling and sealing, are sent to the geologic repository.

An RIC AVS module consists of a conventional stainless steel canister having an internal alumina lined graphite crucible. The crucible holds the HLW/frit mixture to be melted and is thermally insulated from the module's outer steel canister. When inductively heated by a low frequency (~30 Hertz), externally applied, AC magnetic field (~300 Gauss), the graphite/ alumina crucible reaches a high temperature (i.e., ~1500C or greater), while the insulated outer steel canister remains at near ambient temperature. The RIC AVS uses induction heating with copper coils. No electrodes are used in the RIC AVS. The RIC AVS disposes of the crucible with the waste inside the canister. No scheduled repairs or replacement of crucibles is needed, and no subsequent crucible decontamination and decommissioning process is required.

The high temperature materials in the module are exposed to molten glass only once for about a day, instead of the many planned operating cycles for conventional melters. One-time use of the melter means that the RIC AVS module can process a diverse range of HLW compositions, substantially reducing pretreatment requirements. The RIC AVS technology may be the only technology available, which will accept a high-level waste with the diverse chemical constituents found at Hanford.

An operating facility will have 12 modules operating in parallel, such that a failure of a module will not stop system operation. Four canisters a day can be produced with each canister containing 2 to 3 times the amount of HLW as is placed in a conventional canister. This translates into a completion schedule for the entire Hanford high-level waste inventory in 12 years, instead of 30 years as currently planned.

The RIC AVS technology is more economical because the RIC AVS modules will vitrify a higher percentage of HLW – typically 80% – instead of the 25% for conventional melters. This feature reduces the number of disposal canisters by a factor of 2 to 3 and reduces canister disposal costs accordingly. The high-waste-content glass made in the RIC AVS has better leach resistance than low-waste content glass derived from current technology. Therefore, the RIC AVS technology offers greater environmental protection from the natural leaching process.

Ordinary stainless steel canisters holding the vitrified wastes are assumed to corrode and disappear after hundreds of years. The glass form is presumed to provide protection from release of the radioactive elements. However, the RIC AVS graphite crucible inside the stainless steel canister is an additional engineered barrier not found in the older technology. It is expected to survive for millions of years, further protecting the radioactive product glass from the natural leaching process.

The RIC AVS module will be filled with a proprietary process that permits the Module to contain as much melted glass as in a traditional canister. Since the RIC AVS glass will contain up to 80% waste in its glass, compared to 27% in a conventional canister, the RIC AVS process will permit the disposal of 2 to 3 times more waste in each canister as is possible using the conventional process.

After cooling, the RIC AVS Module is sealed, inspected (including for any unexpected external radioactive contamination and decontaminated if necessary), and stored on-site prior to ultimate disposal.

Download a pdf version of the Executive Summary.

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