ML23262B356
| ML23262B356 | |
| Person / Time | |
|---|---|
| Site: | PROJ0734 |
| Issue date: | 09/26/2023 |
| From: | Cynthia Barr NRC/NMSS/DDUWP/RTAB |
| To: | Stephen Koenick NRC/NMSS/DDUWP/LLWPB |
| Shared Package | |
| ML23262B355 | List: |
| References | |
| Download: ML23262B356 (4) | |
Text
MEMORANDUM TO:
Stephen S. Koenick, Branch Chief Low-Level Waste and Projects Branch Division of Decommissioning, Uranium Recovery, and Waste Programs Office of Nuclear Material Safety and Safeguards THRU:
Christepher A. McKenney, Branch Chief Risk and Technical Analysis Branch Division of Decommissioning, Uranium Recovery, and Waste Programs Office of Nuclear Material Safety and Safeguards FROM:
Cynthia S. Barr, Senior Risk Analyst Risk and Technical Analysis Branch Division of Decommissioning, Uranium Recovery, and Waste Programs Office of Nuclear Material Safety and Safeguards
SUBJECT:
TECHNICAL REVIEW: U.S. DEPARTMENT OF ENERGY DOCUMENTATION RELATED TO ANCILLARY EQUIPMENT CLOSURE AT THE F-TANK FARM FACILITY AT THE SAVANNAH RIVER SITE (PROJ0734)
The U.S. Nuclear Regulatory Commission (NRC) has performed a technical review of a collection of documents prepared by the U.S. Department of Energy (DOE) that provide information about closure of ancillary equipmenttwo F-Area diversion boxes known as FDB-5 and FDB-6, at the F-Tank Farm facility at the Savannah River Site in Aiken, SC. This technical review report is the first report to review information on ancillary equipment closure and use of slag-free alternative grouts at the tank farm facilities at SRS.
CONTACT: Cynthia S. Barr, NMSS/DUWP 301-415-4015 September 26, 2023 Signed by McKenney, on 09/26/23 Signed by Barr, Cynthia on 09/26/23
S. Koenick 2
This technical review is associated with Monitoring Area (MA) 1, Inventory and 3, Cementitious Material Performance. Specifically, this technical review supports Monitoring Factors (MFs) 1.1, Final Inventory and Risk Estimates, 1.4, Ancillary Equipment Inventory, and 1.5, Waste Removal (As it Pertains to ALARA); and 3.4, Grout Performance, and 3.6, Waste Stabilization (As it Impacts ALARA).
NRC findings related to Inventory and Final Risk Estimates include the following:
Although no inventory was developed for diversion boxes, such as FDB-5 and FDB-6, in the FTF Performance Assessment (PA), DOE developed an inventory for these diversion boxes to perform a special analysis (SA) to estimate potential doses and support closure of the ancillary equipment. While there is significant uncertainty in the approach used to develop the inventory, NRC staff concludes that the approach used was reasonable given the expected low risk-significance of residual waste remaining in the diversion boxes compared to other sources at the FTF.
NRC recommends that DOE look for opportunities to validate the methods used to develop the ancillary equipment inventory in the FTF PA, including the use of characterization and sampling to support the assumed low risk estimates of ancillary equipment. This will be especially important for potentially plugged transfer lines and jumpers.
The results of the SA using the estimated inventories for FDB-5 and FDB-6 reveal negligible contributions to overall peak dose at FTF. The updated SA estimated the maximum potential dose to a future hypothetical MOP resulting from the waste in FDB-5 at 6 105 mSv/yr (0.006 mrem/yr) and from FDB-6 at 1 104 mSv/yr (0.01 mrem/yr).
Given the apparent low risk associated with residual waste that may be present in the FDB-5 and FDB-6 diversion boxes, NRC staff concur that waste was removed to the maximum extent practical.
In future documentation, DOE should clarify the reason for abandonment of jumpers in the diversion boxes and the expected radiological status of the abandoned jumpers (e.g., the jumpers were plugged and were abandoned prior to waste dissolution; or the jumpers were not plugged or were plugged and abandoned after attempted waste dissolution) to provide a stronger basis for the assumptions that went into estimating the residual volume and concentration of waste remaining in the diversion boxes, particularly since the interior of these jumpers cannot be easily characterized.
NRC findings related to Grout Performance and Waste Stabilization include the following:
Bulk fill reducing tank grout (mix LP#8-16 of C-SPP-F-00055) and clean cap grout (C-SPP-Z-00012) were the only two tank fill grouts previously listed for use in the Consolidated General Closure Plan for F-Area and H-Area Waste Tank Systems (SRR-CWDA-2017-00015, Revision 0). Grout evaluations performed by SRR in support of closing FDB-5 and FDB-6 identified two other cementitious materials that DOE prefers to use to fill ancillary structures at the tank farms: low slump, non-structural concrete (mix A2000-6-0-2-A) and a zero-bleed, controlled low-strength material (ZB-CLSM, also known as ZB-FF-8-D; C-SPS-G-00096).
S. Koenick 3
Low-Slump Concrete (mix A2000-6-0-2-A) is not meant to be a structural concrete, but only needs to plug openings in the sump, so that when the more flowable ZB-CLSM/
ZB-FF-8-D is placed into the diversion box, it does not uncontrollably flow out into other parts of the system. This mix appears appropriate to perform this task. Based upon the similarity between tank fill grout LP#8-16 and ZB-CLSM/ZB-FF-8-D, if ancillary structures, such as diversion boxes, contain insignificant quantities of waste such that chemically imparting reducing conditions on infiltrating water is unnecessary, then slag-free ZB-CLSM/ZB-FF-8-D will likely function in an equivalent physical manner to provide structural stability to ancillary structures.
Docket No. PROJ0734
Enclosure:
Technical Review of Ancillary Equipment Closure cc: D. Pickett, SWRI WIR Service List
Memo ML23262B356 OFFICE NMSS/DUWP/RTAB NMSS/DUWP/RTAB NMSS/DUWP/RTAB NAME CBarr CMcKenney CBarr DATE Sep 19, 2023 Sep 26, 2023 Sep 26, 2023