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Studies are being conducted by the Hanford Waste Vitrification Plant (HWVP) Project on ways to increase the waste processing capacity within the current Vitrification Building structural design. The Phase 1 study on remote systems concepts identification and extent of capacity increase was completed. The study concluded that the HWVP capacity could be increased to four times the current capacity with minor design adjustments to the fixed facility design, and the required design changes would not impact the current footprint of the vitrification building. A further increase in production capacity may be achievable but would require some technology development, verification testing, and a more systematic and extensive engineering evaluation. The primary changes included a single advance melter with a higher capacity, new evaporative feed tank, offgas quench collection tank, ejector venturi scrubbers, and additional inner canister closure station,a smear test station, a new close- coupled analytical facility, waste hold capacity of 400,000 gallon, the ability to concentrate out-of-plant HWVP feed to 90 g/L waste oxide concentration, and limited changes to the current base slab construction package.

The Hanford Waste Vitrification Plant (HWVP) is being designed for the Department of Energy to immobilize pretreated radioactive high-level waste and transuranic waste as glass for permanent disposal. Laboratory studies were conducted to characterize HWVP slurry chemistry during selected processing steps, using pretreated Neutralized Current Acid Waste (NCAW) simulant. Laboratory tests were designed to provide bases for determining the potential for hazardous gas generation, making chemical adjustments for glass redox control, and assessing the potential for rapid exothermic reactions of dried NCAW slurry. Offgas generation rates and the total moles of gas released as a function of selected pretreated NCAW components and process variables were measured. An emphasis was placed on identifying conditions that initiate significant H{sub 2} generation. Glass redox measurements, using Fe{sup +2}/{Sigma}Fe as an indicator of the glass oxidation state, were made to develop guidelines for HCOOH addition. Thermal analyses of dried NCAW simulant were conducted to assess the potential of a rapid uncontrollable exothermic reaction in the chemical processing cell tanks.

Numerous studies (Section 8) have,addressed the Theological properties of simulated process slurries at the Savannah River Laboratory for the Defense Waste Processing Facility and at Pacific Northwest Laboratory`(PNL) for the Hanford Waste Vitrification Plant (HWVP). These studies were reviewed to summarize existing data applicable to HWVP design. The reviewers determined that the existing data provide important information on the effects of feed variability, solids loading, temperature, formating, pH, and scale-up. However, these data cannot serve as a basis for fundamental slurry transport calculations because data are not reported in sufficient detail over a range of shear rates and in appropriate terms to be sufficient for transport calculations.

The design of a slurry-fed electric gas melter and an examination of the performance and condition of the construction materials were completed. The joule-heated, ceramic-lined melter was constructed to test the applicability of materials and processes for high-level waste vitrification. The developmental Liquid-Fed Ceramic Melter (LFCM) was operated for three years with simulated high-level waste and was subjected to conditions more severe than those expected for a nuclear waste vitrification plant.

This document describes a conceptual high-level waste immobilization facility. The facility would have the capability to calcine and then vitrify high-level liquid waste (HLLW). The vitrification would be accomplished in a canister which is seal-welded, checked for integrity, and decontaminated for movement to storage. Included in the facility would be the capability to repair faulty canister-lid seal welds, overpack failed canisters, and treat the process off-gas and cell ventilation air prior to release to the fuel reprocessing plant (FRP) atmospheric protection system (APS). The nuclear waste vitrification facility (NWVF) would be an integral part of the FRP structure. The operations of the facilities would be centered in the waste vitrification cell (WVC) which performs most of the facility functions. The cell is a reinforced concrete hot cell, lined with stainless steel. Most operation and maintenance activities would be performed remotely using a crane equipped with an impact wrench or yoke. The major facility equipment includes a feed tank, spray calciner, two melters, weld-inspection stations, canister storage rack, and a canister decontamination cubicle. Installation and removal of equipment in the cell would be done through shielding doors. The air lock system of the canister decontamination cubicle would permit placement and removalmore » of the canister. Activities in the cell may be observed through four shielding glass windows and/or up to three periscopes. The operating, service, and pipe galleries which house operating personnel and equipment necessary for cell operations are located adjacent to the cell.« less

This technical manual summarizes process and equipment technology developed at Pacific Northwest Laboratory over the last 20 years for vitrification of high-level liquid waste by the Spray Calciner/In-Can Melter process. Pacific Northwest Laboratory experience includes process development and demonstration in laboratory-, pilot-, and full-scale equipment using nonradioactive synthetic wastes. Also, laboratory- and pilot-scale process demonstrations have been conducted using actual high-level radioactive wastes. In the course of process development, more than 26 tonnes of borosilicate glass have been produced in 75 canisters. Four of these canisters contained radioactive waste glass. The associated process and glass chemistry is discussed. Technology areas described include calciner feed treatment and techniques, calcination, vitrification, off-gas treatment, glass containment (the canister), and waste glass chemistry. Areas of optimization and site-specific development that would be needed to adapt this base technology for specific plant application are indicated. A conceptual Spray Calciner/In-Can Melter system design and analyses are provided in the manual to assist prospective users in evaluating the process for plant application, to provide equipment design information, and to supply information for safety analyses and environmental reports. The base (generic) technology for the Spray Calciner/In-Can Melter process has been developed to a point at which it ismore » ready for plant application.« less

In hydrothermal environment tests, three simulated high-level waste (HLW) glasses, supercalcine, and SYNROC exhibit similar leaching behavior. Releases from the glasses are lowest at temperatures below 250/sup 0/C (the expected repository temperature range). Corrosion tests of candidate metallic-container materials in 250/sup 0/C Hanford ground water are under way and a group of polymers that shows good resistance to 200/sup 0/C water in autoclave tests is undergoing gamma irradiation. Methods of reducing melt-foaming in ceramic melters were investigated. Inclusion of monoxides of iron, nickel and manganese in the calcine significantly improved melt quality and reduced foaming. The addition of cornstarch to the melt, which inhibits foaming in laboratory studies, continues to be evaluated. A successful pilot-scale test of the Spray Calciner/In-Can Melter process was done using simulated waste representing the combined contents of the neutralized and Thorex waste tanks at the Western New York Nuclear Service Center. Flexibility of the process for handling high-sodium waste was demonstrated.