Analysis of SX farm leak histories -- Historical leak model (HLM)
This report uses readily available historical information to better define the volume, chemical composition, and Cs-137/Sr-90 amounts for leaks that have occurred in the past for tanks SX-108, SX-109, SX-111, and SX-112. In particular a Historical Leak Model (HLM) is developed that is a month by month reconciliation of tank levels, fill records, and calculated boil-off rates for these tanks. The HLM analysis is an independent leak estimate that reconstructs the tank thermal histories thereby deriving each tank`s evaporative volume loss and by difference, its unaccounted losses as well. The HLM analysis was meant to demonstrate the viability of its approach, not necessarily to establish the HLM leak estimates as being definitive. Past leak estimates for these tanks have invariably resorted to soil wetting arguments but the extent of soil contaminated by each leak has always been highly uncertain. There is also a great deal of uncertainty with the HLM that was not quantified in this report, but will be addressed later. These four tanks (among others) were used from 1956 to 1975 for storage of high-level waste from the Redox process at Hanford. During their operation, tank waste temperatures were often as high as 150 C (300 F), but were more typically around 130 C. The primary tank cooling was by evaporation of tank waste and therefore periodic replacement of lost volume with water was necessary to maintain each tank`s inventory. This active reflux of waste resulted in very substantial turnovers in tank inventory as well as significant structural degradation of these tanks. As a result of the loss of structural integrity, each of these tanks leaked during their active periods of operation. Unfortunately, the large turnover in tank volume associated with their reflux cooling has made a determination of leak volumes very difficult. During much of these tanks operational histories, inventory losses because of evaporative cooling could have effectively masked any volume loss due to leak. However, careful comparison with reported tank levels during certain periods clearly show unaccounted volume losses for many tanks. As a result of the HLM analysis, SX-108, SX-109, SX-111, and SX-112 all show clear evidence of unaccounted volume losses during the period 1958 to 1975. Likewise, the HLM does not show similar unaccounted volume losses for tank SX-105, a tank with no reported leak history, verifying that the HLM is consistent with SX-105 not leaking. These unaccounted volume losses establish the leak start date and rate, and when propagated over time show that SX-108 lost 203 kgal followed by SX-109 at 111. SX-111 at 55, and SX-112 at 44 kgal.0664 These leak volumes represent maximum or upper bounds estimates of each leak and are in total volume about six times the previous leak estimates.
- Research Organization:
- Fluor Daniel Hanford, Inc., Richland, WA (United States)
- Sponsoring Organization:
- USDOE Office of Environmental Restoration and Waste Management, Washington, DC (United States)
- DOE Contract Number:
- AC06-96RL13200
- OSTI ID:
- 362607
- Report Number(s):
- HNF-3233; ON: DE99050976; BR: EW3130000; TRN: AHC29926%%262
- Resource Relation:
- Other Information: PBD: 20 Aug 1998
- Country of Publication:
- United States
- Language:
- English
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