The Accelerated Basin De-inventory (ABD) program involves discarding spent nuclear fuel that is currently stored in L-Basin to the Defense Waste Processing Facility (DWPF) for vitrification. The first ABD discards will occur during the preparation of Sludge Batch (SB) 11. Savannah River Mission Completion has requested that the Savannah River National Laboratory assess the technical gaps related to the increased gadolinium poisoning requirement and the impacts of performing the Low Temperature Aluminum Dissolution (LTAD) process in Tank 51 with H-Canyon discards present.The following summarizes the evaluation of the impacts of increasing the quantity of gadolinium (and related topics) from what was previously evaluated in the SRNL studies of gadolinium-poisoned ABD material solubility, the overall ABD flowsheet review, and increasing the fissile mass loading in glass: Based on literature surveys, there is no indication that organic interactions with gadolinium will be significant at the high pH (typically >13) conditions of the Concentration, Storage, and Transfer Facilities. Any interactions of gadolinium with organics in DWPF are not expected to adversely impact DWPF or downstream facilities. Thus, there is little-to-no residual risk from organic interactions with gadolinium. [Gap closed] Increasing the gadolinium mass ratio to 3.0:1 Gd: 235 U(eq SLU ) should lead to the same or higher partitioning of gadolinium into the solid phase within the DWPF Chemical Process Cell, resulting in both liquid and solid phases with expected partitioning of Gd consistent with the prior solubility study. [Gap closed for SB11] There are no expected impacts on DWPF melt temperature and melter operations due to the minimal ~0.2 weight percent (wt%) increase in Gd concentration relative to previous sludge batches.[Gap closed for SB11] As observed previously, Gd is expected to enter the off-gas system via physical entrainment, but at a slightly higher concentration than what was observed for SB9 melter off-gas pluggage deposits (0.07 wt%). [Gap closed for SB11] There are no expected impacts on DWPF recycle or the Recycle Collection Tank glycolate destruction process. [Gap closed for SB11] Gd is projected to be a trace component in the SB11 glass (<0.5 wt%) and can be ignored for process control. Trace components do not significantly impact glass durability, thus the conclusions of the previous Product Consistency Test evaluation at a fissile mass loading of 2,500 g fissile/m 3 glass still applies to SB11. The ~0.1 wt% increase in Gd 2 O 3 concentration relative to the previous study will not impact the predictability of SB11 glass with the DWPF Product Composition Control System (PCCS) models for durability or the acceptability of glass according to the Waste Acceptance Product Specifications (WAPS) criterion for product consistency. [Gap closed for SB11] No additional Toxicity Characteristic Leaching Procedure testing is necessary for SB11 and the hazardous waste specification of the SB11 DWPF waste form is unchanged a...
Substantial changes to the report are tracked by revision bars. Changes in the headers, footers, Table of Contents, List of Tables, and reference numbering are not tracked by revision bars. • Title Page: Replaced page i to reflect the current SRNL report template • Executive Summary: Added a conclusion regarding soluble enriched uranium.Added a conclusion that allowing for concurrent transfers of sodium hydroxide and Accelerated Basin De-inventory (ABD) material does not alter the conclusions of the document. Removed a recommendation regarding depleted uranium additions and the impact on soluble enriched uranium. Added a recommendation for Savannah River Mission Completion (SRMC) to evaluate the applicable risk. • Section 1.0: Added description of email request for technical evaluation of allowing concurrent transfers of sodium hydroxide and ABD material. Added a clarification of the depleted uranium addition plan. • Section 3.1: Added a clarification of the depleted uranium addition plan.• Section 3.1.3: Described the depleted uranium addition plan and gave a more detailed description of its impacts on the supernate uranium enrichment in Tank 51. Described the risks involved. • Section 3.1.4: Changed the wording to indicate a risk involving uranium enrichment of Tank 51 supernate • Section 3.2.2.2, changed free hydroxide concentration from "0.6 to 1.2 mol/L" to ">1.2 mol/L" • Section 3.3: New section containing a technical evaluation of allowing concurrent transfers of sodium hydroxide and ABD material. Specific areas addressed included aluminum removal, actinide enrichment in the decanted supernate, rheological behavior, and Gd solubility. • Section 4.0: Added a conclusion regarding soluble enriched uranium. Added a conclusion that allowing for concurrent transfers of sodium hydroxide and ABD material does not alter the conclusions of the document. Removed a recommendation regarding depleted uranium additions and the impact on soluble enriched uranium. Added a recommendation for SRMC to evaluate the applicable risk. • Section 5.0: Added Reference 9 and updated References 15, 16, and 31.
For each sludge batch that is processed in the Defense Waste Processing Facility (DWPF), the Savannah River National Laboratory (SRNL) performs qualification testing to demonstrate that the sludge batch (SB) is processible. During processing of SB9, DWPF will be transitioning from the Nitric-Formic Acid (NFA) flowsheet to the Nitric-Glycolic Acid (NGA) flowsheet. Thus, the qualification of SB10 was requested to only be performed using the NGA flowsheet.In order to qualify the batch for the NGA flowsheet, Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) cycles, designated SC-19, were performed using SB10 Tank 51 sample material. SRNL received Tank 51 material in the midst of Tank Farm washing. SRNL continued the washing in the SRNL Shielded Cells. The SRNL process included the addition of Sodium Reactor Experiment (SRE) material from H Canyon, simulating the transfer of SRE from H Canyon to Tank 51 during Tank Farm washing. The washed SB10 Tank 51 material, with SRE, was characterized prior to flowsheet qualification testing.The Chemical Process Cell demonstration with the NGA flowsheet utilized an acid stoichiometry of 107% Koopman Minimum Acid basis (102% Hsu basis). The qualification was performed on the "batch", which is representative of the Tank 51 material that will be transferred to Tank 40, rather than the "blend", which is representative of the Tank 40 material that will be fed to DWPF. Thus, specifics for the DWPF processing of the Tank 40 blend may differ in varying degrees from this qualification test. Additionally, the qualification did not include Salt Waste Processing Facility (SWPF) feeds (Monosodium Titanate (MST)/Sludge Solids and Strip Effluent), which would contribute soluble salts and the MST solids, which could influence the acid addition and the product rheology, respectively. For these reasons, the results of this qualification testing demonstration are used in conjunction with simulant testing to inform the processing of the Tank 40 blend with inclusion of SWPF feeds.Highlights of the testing results are summarized in the paragraphs below.Prior to the addition of antifoam, foaming was encountered in the SRAT cycle during the addition of nitric acid to the extent that sludge foamed over into the off-gas system. Based on observations from simulant testing, during which foaming was not noted during nitric acid addition, the plan involved addition of Momentive TM Y-17112 antifoam after the completion of nitric acid addition and prior to glycolic acid addition. The foaming during nitric acid addition was likely due to the release of carbon dioxide from the acid reacting with carbonate. After a time out (3 weeks), the SRAT cycle was resumed with an antifoam addition prior to resumption of nitric acid addition. Foaming was successfully mitigated during the remainder of the SRAT and SME cycles.Total dried solids measurements of the SRAT and SME Products were 20.1 and 48.1 weight percent (wt%), respectively. Calcined solids measured 11.3 wt% in the SRAT Receipt and SRAT Pr...
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