Electrometallurgical Techniques for DOE Spent Fuel Treatment: An Assessment of Waste Form Development and Characterization (1999)

The U.S. Department of Energy (DOE) has developed a set of performance criteria to aid in determining the success of the demonstration project. These success criteria were developed in response to the committee 's recommendation in a previous report.¹ The committee has assessed these criteria and has found them to be adequate for judging the success of the demonstration project. ²

Criterion 1: Demonstration that 125 EBR-II assemblies can be treated in a fuel-conditioning facility (FCF) within three years, with a throughput rate of 16 kg/month for driver assemblies sustained for a minimum of three months and a blanket throughput rate of 150 kg per month sustained for one month.

Specific goals to meet criterion 1:

1. Freeze process modifications and operating parameters while demonstrating a continuous throughput of 16 kg of driver uranium for three consecutive months.

2. Demonstrate the capability to electrorefine approximately 150 kg of blanket spent fuel in one month.

3. Distill the electrolyte from electrorefiner cathode products through the cathode processor in an FCF and blend the resulting ingot with depleted uranium in the casting furnace to produce a low-enriched uranium storage ingot.

4. Specify acceptable operating parameters and throughput for the cathode processor to meet uranium product specifications and electrorefiner production rates of 16 kg of driver uranium for three consecutive months.

5. Specify acceptable casting-furnace operating parameters for producing low-enriched uranium from 16 kg driver uranium per month for 3 consecutive months.

6. Cast three batches of irradiated cladding hulls (two driver assemblies per batch) into a typical metal waste form (stainless steel −15 percent zirconium).

7. Process 3 kg of salt containing approximately 6 weight % fission products into 10 ceramic waste samples.

Criterion 2: Quantification (for both composition and mass) of recycle, waste, and product streams that demonstrate projected material balance with no significant deviations.

Specific goals to meet criterion 2:

1. Develop uranium product specifications with a range of acceptable impurities: plutonium, neptunium, technetium-99 and ruthenium-106. Specify process-operating parameters for uranium ingots that meet uranium specifications.

2. Develop metal waste specifications that are based on performance characterization results of small samples with variations in the principal constituents: zirconium, uranium, technetium, plutonium, neptunium, and noble metals. Determine performance characterization with electrochemical techniques, corrosion tests, vapor hydration tests, and attribute tests.

3. Develop metal waste process specifications for major process variables: operating temperatures, hold time, and cooling rate.

4. Develop ceramic waste specifications that are based on performance characterization results of samples with principal constituent variations: glass, fission products, uranium, and plutonium. Determine performance characteristics with attribute, characterization, accelerated, and service-condition tests.

5. Develop ceramic waste process specifications for major process variables: free chloride, zeolite moisture content, and chloride per unit cell.

6. Quantify volume of low-level and transuranic waste generation under standard operating conditions.

7. Return the cathode processor condensate to the individual electrorefiners during the 16 kg driver per month for three months and 150 kg blanket per month operations.

8. Specify unit process operations for metal spent fuel treatment, uranium ingot production, and waste form production.

9. Estimate mass balances for uranium, transuranics, sodium, and key fission products for overall process.

10. Prepare the flowsheet and develop process specifications for the subsequent inventory operation.

Criterion 3: Demonstration of an overall dependable and predictable process, considering uptime, repair and maintenance, and operability of linked process steps.

Specific goals to meet criterion 3:

1. Record facility and equipment availability for process operations during the three-month, 16 kg per month driver demonstration.

2. Record process interruption for chemistry results during the three-month operation at 16 kg per month.

3. Develop quantitative process models for each key step in the treatment process.

4. Develop a process model that estimates throughputs as a function of equipment availability, maintenance requirements, and individual process times.

Criterion 4: Demonstration that safety risks, environmental impacts, and nuclear materials accountancy are quantified and acceptable within regulatory limits.

Specific goals to meet criterion 4:

1. Demonstrate that the FCF air emissions result in an effective dose equivalent to the public of less than 10 mrem per year, which is the limit in DOE Order 5400.5

and is less than the 25-mrem-per-year limit in the State of Idaho Permit to Construct Air Pollution Emitting Source.

2. Show that FCF personnel exposure is less than 0.5 rem per year average and 1.5 rem per year for the maximum individual exposure, which is a factor of 3 less than the DOE Occupational Radiation Protection Final Rule 10CFR835 limit that is 5 rem per year.

3. Demonstrate a material control and accountability system that shows the historical inventory difference for uranium and plutonium is within control limits based on variance propagation of measurement and sampling errors, as specified in DOE Order 5633.3B.

4. Record any unlikely and extremely unlikely accident (as defined in the Final Safety Analysis Report) during the demonstration.

5. Estimate the safety risks, environmental impacts, and material accountancy for the inventory operations.