Flowsheet Development Support

Company Performed Work:

AEM Consulting, LLC

Work Description:

 This activity supports the development of flow sheets for feeding waste to the WTP.  The first flow sheet was completed in Fiscal Year 2010 (flowsheet for 241-AY-102).  The second and third flowsheets were completed in Fiscal Year 2011.  Unlike the first flowsheet which used the current waste inventory in AY-102, the next two flowsheets were based on projections of tank composition after multiple transfers of waste have occurred.  The HTWOS run used to develop System Plan 5, RPP‑RPT‑47464 PRELIMINARY A AND AX TANK FARMS RETRIEVAL PROCESS FLOWSHEET, and the Best Basis Inventory (BBI) was used to project the compositions of the feed tanks.

The second flowsheet is for tank 241‑AZ‑101 (AZ‑101).  The waste was based on the existing tank inventory and a sufficient quantity of waste from tank 241‑C‑102 (C‑102) to produce a settled solids layer of ~70 inches.  The flowsheet includes an analysis for both “washed” and “unwashed” solids from C‑102.  The supernatant composition is assumed to be the same as predicted by HTWOS but the volume was increased such that AZ‑101 is full (364 inches of waste) prior to delivery to the WTP.

The third flowsheet is for tank 241‑AZ‑102 (AZ‑102).  The waste was based on the predicted tank composition from RPP‑RPT‑47464 and the remainder of the C‑102 waste not included with AZ‑101.  Supernatant was assumed to be removed from AZ‑102 to create the space necessary for the additional C‑102 solids.  The flowsheet includes an analysis for both “washed” and “unwashed” solids from C‑102.  The supernatant composition was assumed to be the same as predicted by RPP‑RPT‑47464.

Both of the flow sheets were developed using average feed concentration of the tank waste for each batch.  The amount of glass was not determined for either scenario.  The flowsheets compare the feed compositions to the limits identified in the System Plan for High Level Waste, Low Activity Waste, and Hydrogen Generation Rate.

Procedure TFC-ENG-CHEM-C-01, Process Flow sheets, was followed in principal to develop these preliminary analyses of the flow sheets, although some variations from the procedure was allowed with agreement of the WRPS’s point of contact because of the uncertainty in the feed composition.  An EXCEL spreadsheet was used to determine the material balance for all the feed scenarios.

As work was completed on the original work scope, it was determined that an additional flowsheet could be completed within the available funds.  Therefore, preparation of an additional waste feed delivery flowsheet for tank 241-AW-105 was approved by the client.  Overall the project resulted in preparation of three preliminary flowsheet documents (AZ-101 as the 2nd HLW Feed Tank, AZ-102 as the 3rd HLW Feed Tank, and AW-105 as an alternative for the 2nd HLW Feed Tank).

A major purpose for the preliminary flowsheets was identification of potential risks associated with completion of the final flowsheets.  This was evaluated by identifying both WTP waste acceptance criteria and tank farm requirements that are potentially applicable to the final flowsheet development.  Many of the WTP waste acceptance criteria were not considered to be finalized at the time of preliminary flowsheet development.  A majority of the requirements were evaluated based on the preliminary flowsheet material balances (evaluation of selected requirements were omitted from the study scope), risk of non-compliance with requirements identified, and potential methods for mitigating risks were identified.

Start / End Date:

February 2011 through September 2011

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