Results of Vapor Space Monitoring of Flammable Gas Watch List Tanks

Mccain, D.J.

doi:10.2172/804812

Cited by 16 publications

(28 citation statements)

References 5 publications

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“…Re-examination of the level drops as determined by the auto FIC, manual FIC, manual tape, and manual radar is also given in the table as "New." Given the uncertainties in the level data as exemplified by the glaring disparities between different level instruments, and the subjectivity in interpreting the data, the level drops determined by McCain (1999) and those labeled "New" in the table compare reasonably well with each other and with the level drops derived from gas monitoring data except for the events on September 3, 1992, andJune 26, 1993. The manual radar during the event on September 3, 1992 shows extreme (4 in.)…”

Section: Jan/1/95mentioning

confidence: 55%

“…Grab samples are also collected automatically when a high-level alarm is activated by a monitoring instrument. A description of the sampling system and the analytical method is given by McCain (1999). The SHMS grab samples have been analyzed for permanent gases by mass spectrometry at the PNNL 325 Laboratory.…”

Section: -4mentioning

confidence: 99%

“…The SHMS grab samples have been analyzed for permanent gases by mass spectrometry at the PNNL 325 Laboratory. Table 6-4 lists the SHMS grab sample results for the FGWL DSTs (McCain 1999). The H2 averages include the reported detection limits, when no HZ was detected in the sample.…”

Section: -4mentioning

confidence: 99%

“…The gas was assumed to be stored in the waste at 2.1 atm, and the hydrogen Fraction of the released gas was assumed to be 0.3. The resulting computed waste level drops, together with the measured waste level drops from McCain (1999), are presented in Table 8-7. Re-examination of the level drops as determined by the auto FIC, manual FIC, manual tape, and manual radar is also given in the table as "New."…”

Section: Jan/1/95mentioning

confidence: 99%

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Data Observations on Double Shell Tank (DST) Flammable Gas Watch List Tank Behavior

Hedengren¹

2000

115

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Section: Jan/1/95mentioning

confidence: 55%

Section: -4mentioning

confidence: 99%

Section: -4mentioning

confidence: 99%

Section: Jan/1/95mentioning

confidence: 99%

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Data Observations on Double Shell Tank (DST) Flammable Gas Watch List Tank Behavior

Hedengren¹

2000

115

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“…Over two hundred spontaneous GREs have been observed in SSTs between 1995, when the Standard Hydrogen Monitoring Systems (SHMS) were installed in SSTs, and July 2000 (McCain 2000. The mean estimated hydrogen release volume of all these releases is only 0.5 cubic meters.…”

Section: Spontaneous Gas Releasesmentioning

confidence: 99%

Gas Releases During Saltcake Dissolution for Retrieval of Single-Shell Tank Waste

Stewart¹

2001

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It is possible to retrieve a large fraction of soluble waste from the Hanford single-shell waste tanks (SST) by dissolving it with water. This retrieval method will be demonstrated in U-107 and S-112 in the next few years. If saltcake dissolution proves practical and effective, many of the saltcake SSTs may be retrieved by this method. Many SSTs retain a large volume of flammable gas that will be released into the tank headspace during retrieval as the waste dissolves. This report describes the physical processes that control dissolution and gas release. Calculation results are shown describing the headspace hydrogen concentration transient during dissolution. The observed spontaneous and induced gas releases from SSTs are summarized, and the dissolution of the crust layer in SY-101 is discussed as a recent example of full-scale dissolution of saltcake containing a very large volume of retained gas. The report concludes that the dissolution rate is self-limiting, and gas release rates are relatively low. iv v Executive SummarySaltcake dissolution is a proposed method for retrieving water-soluble salts from the Hanford SSTs. Water will be sprayed on the waste surface to dissolve the soluble fraction of the waste while the resulting brine is pumped out of the tank with an existing saltwell pumping system. Because a large fraction of typical saltcake waste is soluble, most of the waste in an SST can, in principle, be retrieved with almost the same time and cost as a typical interim stabilization campaign. A proof-of-concept test (limited to approximately 100,000 gal of brine) is planned in U-107 during the fall of 2001. A full-tank retrieval demonstration system is being planned for S-112 in 2002. If saltcake dissolution proves practical and effective, many of the saltcake SSTs may be retrieved by this method.Many of the SSTs contain a large volume of flammable gas that will be released into the tank headspace as the waste dissolves. U-107 contains 180 ± 60 cubic meters (6,400 ± 2,000 scf) of retained gas, and S-112 is estimated to retain a much smaller volume of 46 ± 23 cubic meters (1,600 ± 800 scf). This report investigates the potential hazard of flammable gas that will be released during the dissolution process.Dissolution is expected to release this gas in proportion to the fraction of the waste in which the soluble solids are dissolved. This process is self-limiting and controllable. Water or dilute brine capable of dissolving solids is less dense than the saturated liquid in equilibrium with the solids. Therefore, the solvent cannot penetrate below the pre-existing interstitial liquid in the waste; and dissolution can only occur in waste that is not saturated with liquid. Once the solvent has become saturated, it is no longer capable of further dissolution and forms a barrier to the less dense liquid from above.This means that dissolution, and the associated gas release, can proceed no faster than the interstitial liquid can drain away. This is the primary mechanism that limits dissolution-induced g...

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Analysis of Induced Gas Released During Retrieval of Hanford Double-Shell Tank Waste

Wells¹,

Cuta²,

Hartley³

et al. 2002

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Radioactive waste is currently scheduled to be retrieved from Hanford double-shell tanks AN-103, AN-104, AN-105 and AW-101 and transferred to the vitrification plant beginning about 2009. Retrieval may involve decanting the supernatant liquid and/or mixing the waste with jet pumps. In these four tanks, which contain relatively large volumes of retained gas, both of these operations are expected to induce buoyant displacement gas releases that can potentially raise the tank headspace hydrogen concentration to very near the lower flammability limit. This report describes the theory and detailed physical models for both the supernate decant and jet mixing processes and presents the results from applying the models to these operations in the four tanks. The technical bases for input parameter distributions are elucidated. xiv

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Results of Vapor Space Monitoring of Flammable Gas Watch List Tanks

Cited by 16 publications

References 5 publications

Data Observations on Double Shell Tank (DST) Flammable Gas Watch List Tank Behavior

Data Observations on Double Shell Tank (DST) Flammable Gas Watch List Tank Behavior

Gas Releases During Saltcake Dissolution for Retrieval of Single-Shell Tank Waste

Analysis of Induced Gas Released During Retrieval of Hanford Double-Shell Tank Waste

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