ISOPAR L Release Rates from Saltstone Using Simulated Salt Solutions
The Modular Caustic-Side Solvent Extraction (CSSX) Unit (MCU) and the Salt Waste Processing Facility (SWPF) will produce a Deactivated Salt Solution (DSS) that will go to the Saltstone Production Facility (SPF). Recent information indicates that solvent entrainment in the DSS is larger than expected. The main concern is with Isopar{reg_sign} L, the diluent in the solvent mixture, and its flammability in the saltstone vault. If it is assumed that all the Isopar{reg_sign} L is released instantaneously into the vault from the curing grout before each subsequent pour; the Isopar{reg_sign} L in the vault headspace is well mixed; and each pour displaces an equivalent volume of headspace, the allowable concentration of Isopar{reg_sign} L in the DSS sent to SPF has been calculated at approximately 4 ppm. The amount allowed would be higher, if the release from grout were significantly less. The Savannah River National Laboratory was tasked with determining the release of Isopar{reg_sign} L from saltstone prepared with a simulated DSS with Isopar{reg_sign} L concentrations ranging from 50 mg/L to 200 mg/L in the salt fraction and with test temperatures ranging from ambient to 95 C. The results from the curing of the saltstone showed that the Isopar{reg_sign} L release data can be treated as a percentage of initial concentration in the concentration range studied. The majority of the Isopar{reg_sign} L that was released over the test duration was released in the first few days. The release of Isopar{reg_sign} L begins immediately and the rate of release decreases over time. At higher temperatures the immediate release is larger than at lower temperatures. In one test at 95 C essentially all of the Isopar{reg_sign} L was released in three months. Initial curing temperature was found to be very important as slight variations during the first few days affected the final Isopar{reg_sign} L amount released. Short scoping tests at 95 C with solvent containing all components (Isopar{reg_sign} L, extractant, suppressor, and modifier) released less Isopar{reg_sign} L than the tests run with Isopar{reg_sign} L. Based on the scoping tests, the Isopar{reg_sign} L releases reported herein are conservative. Isopar{reg_sign} L release was studied for a two-month period and average cumulative yield distributions were produced. From an SPF pouring perspective where saltstone will be poured in a shorter time period of one to two weeks, prior to being capped, the release of Isopar{reg_sign} L occurring in two weeks is more important. The average percentages of Isopar{reg_sign} L released after 13 days from saltstone are, to one sigma standard deviation: 60% {+-} 17% at 95 C, 13% {+-} 4.3% at 75 C, and 4.6% {+-} 1.2% at ambient temperature.
- Research Organization:
- Savannah River Site (SRS), Aiken, SC (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- DE-AC09-96SR18500
- OSTI ID:
- 890224
- Report Number(s):
- WSRC-TR-2005-00568; TRN: US0604630
- Country of Publication:
- United States
- Language:
- English
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