Radiation chemical effects on radiochemistry: A review of examples important to nuclear power

Mincher, Bruce J.; Mezyk, Stephen P.

doi:10.1524/ract.2009.1646

Cited by 58 publications

(77 citation statements)

References 125 publications

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“…Acetate and several other unknown degradation products of both lactic acid and DTPA were detected by HPLC analysis. Several species arising from the degradation of CMPO ([(iBu) 2 NPrH] + , [(iBu) 2 PrH 2 ] + and CMPO-carboxylic acids) were determined by ESI-MS; which is consistent products identified in previous studies.…”

Section: Discussionsupporting

confidence: 84%

“…The radiation chemistry of the TBP was recently reviewed by Mincher and co-authors. [1,2] Further, Mincher et al have also recently reviewed the radiation chemistry of organophosphorus extractants such as octylphenyl-N,Ndiisobutylcarbamoylmethyl phosphine oxide (CMPO), one of the components of the TRUEX process solvent. [3] The current TRUEX flowsheet concept considered by the Fuel Cycle Research Development program is intended to separate the trivalent actinides and lanthanides from the Raffinate of a U/Pu separation process.…”

Section: Discussionmentioning

confidence: 99%

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Characterization of radiolytically generated degradation products in the strip section of a TRUEX flowsheet

Peterman¹,

Olson²,

Groenewold³

et al. 2013

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SUMMARYThis report presents a summary of the work performed to meet the FCRD level 2 milestone M3FT-13IN0302053, "Identification of TRUEX Strip Degradation." The effects of gamma radiolysis upon the efficacy of the strip section of a TRUEX flowsheet for the recovery of trivalent actinides and lanthanides from acidic solution were determined by a combination of static and test loop irradiations. Compositions of the irradiated aqueous and organic solutions were determined using a suite of analytical techniques. In addition, ESI-MS was used to identify some of the products of the radiolytic degradation of lactic acid, DTPA, CMPO, and TBP.For lactic acid, the major degradation products detected by ESI-MS were pyruvic acid and a species corresponding to a lactic acid-pyruvic acid cluster. The major product of DTPA degradation was determined by ESI-MS to be a DTPA lactam resulting from the radiolytic loss of glycolic acid. Acetate and several other unknown degradation products of both lactic acid and DTPA were detected by HPLC analysis. Several species arising from the degradation of CMPO ([(iBu) 2 NPrH] + , [(iBu) 2 PrH 2 ] + and CMPO-carboxylic acids) were determined by ESI-MS; which is consistent products identified in previous studies.The generally lower G-values determined for test loop irradiation compared to static irradiation experiments clearly points out the importance of performing radiolytic degradation studies using oxygenated, mixed aqueous and organic solutions. The actual mechanism by which dissolved oxygen present in the test loop ameliorates the radiolytic degradation is not known. However, the rapid reaction of oxygen with carbon centered radicals would produce less reactive peroxyl radicals. Further studies are necessary in order to develop a complete understanding of the role played by dissolved oxygen in the inhibition of radiolytic degradation of solvent extraction process solvents.Gamma radiolysis results in a small increase the distribution ratios in the strip section of the TRUEX flowsheet (D Am = <0.001 at 0 kGy absorbed dose to D Am = 0.015 at 1300 kGy absorbed). Even the distribution ratio determined for the highest absorbed dose is not expected to adversely impact operation of the stripping section of the TRUEX flowsheet. However, the generation of degradation products in the aqueous phase and the radiolytic destruction of lactic acid and DTPA may have serious impacts on a subsequent TALSPEAK process. Close coupling of the TRUEX and TALSPEAK operations may help to mitigate these effects by limiting the gamma dose to the strip product solution.

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Section: Discussionsupporting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Characterization of radiolytically generated degradation products in the strip section of a TRUEX flowsheet

Peterman¹,

Olson²,

Groenewold³

et al. 2013

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“…In the presence of dissolved oxygen and nitric acid, the strongly reducing solvated electron, aq e , (produced via direct radiolysis of water) is rapidly converted to other species according to the following equations [16] Therefore, the presence of dissolved oxygen in the test loop during irradiation may serve to convert highly reactive radical species into molecular species, i.e. H 2 O 2 , which exhibit less reactivity.…”

Section: Discussionmentioning

confidence: 99%

“…The radiation types are predominantly low linear energy transfer (LET) beta/gamma radiation from fission product decay, and high LET alpha radiation from actinide decay. The major reactive species formed [3,4] Due to relatively low ligand concentrations employed most decay energy is absorbed by the diluent and ligand radiolysis is expected to occur by indirect, rather than direct mechanisms. [5] For example, the proposed TRUEX solvent contains 0.2 M CMPO as the ligand, while the tributylphosphate (TBP) modifier and dodecane diluent concentrations are about 1.4 M and 3 M, respectively.…”

Section: Introductionmentioning

confidence: 99%

TRUEX Radiolysis Testing Using the INL Radiolysis Test Loop: FY-2012 Status Report

Peterman¹,

Olson²,

Tillotson³

et al. 2012

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SUMMARYThis report presents a summary of the work performed to meet the FCRD level 3 milestone M3FT-12IN0302032, "TRUEX strip/TALSPEAK feed degradation mechanism." The INL radiolysis test loop has been used to evaluate the effects of radiolytic degradation upon the efficacy of the strip section of the TRUEX flowsheet for the recovery of trivalent actinides and lanthanides from acidic solution. The nominal composition of the TRUEX solvent used in this study is 0.2 M CMPO and 1.4 M TBP dissolved in n-dodecane and the nominal composition of the TRUEX strip solution is 1.5 M lactic acid and 0.050 M diethylenetriaminepentaacetic acid. Gamma irradiation of a mixture of TRUEX process solvent and stripping solution in the test loop does not adversely impact flowsheet performance as measured by stripping americium ratios. The observed increase in americium stripping distribution ratios with increasing absorbed dose indicates the radiolytic production of organic soluble degradation compounds. While the observed increases in the americium stripping distributions with increasing absorbed dose are statistically significant, the increase from D Am = <0.001 at 0 kGy absorbed dose to D Am = 0.015 at 1300 kGy absorbed dose is not an insurmountable difficulty. A more troubling observation is the significant decrease in the solvent dispersion number as the strip section of the TRUEX flowsheet is subjected to gamma radiolysis. The dispersion number, N Di , determined for un-irradiated TRUEX solvent and strip solution is N Di = 1.05 x 10 -3 , which is an acceptable value for typical solvent extraction equipment. However, the dispersion number for the irradiated TRUEX solvent and strip solution is 3.94 x 10 -4 , which is a poor value for typical solvent extraction equipment. Dispersion number determinations for mixture of irradiated and un-irradiated solutions suggest that both the aqueous and organic phases play a role in the decrease of the solvent dispersion number.

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“…The radiation types are predominantly low linear energy transfer (LET) beta/gamma radiation from fission product decay, and high LET alpha radiation from actinide decay. The major reactive species formed 3,4 by radiolysis of water, alkane diluent, and nitric acid are shown in Equations 1 -3, respectively. Due to relatively low ligand concentrations employed most decay energy is absorbed by the diluent and ligand radiolysis is expected to occur by indirect, rather than direct mechanisms.…”

mentioning

confidence: 99%

Summary of TRUEX Radiolysis Testing Using the INL Radiolysis Test Loop

Peterman¹,

Olson²,

McDowell³

et al. 2012

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SUMMARYThe INL radiolysis and hydrolysis test loop has been used to evaluate the effects of hydrolytic and radiolytic degradation upon the efficacy of the TRUEX flowsheet for the recovery of trivalent actinides and lanthanides from acidic solution. The results demonstrate that solvent hydrolysis does not adversely impact the performance of the process flowsheet.The nominal composition of the TRUEX solvent used in this study is 0.2 M CMPO and 1.4 M TBP dissolved in n-dodecane. Gamma irradiation of a mixture of TRUEX process solvent and nitric acid in the test loop does adversely impact flowsheet performance as measured by the decreasing americium and europium distribution ratios in the extraction section as accumulated dose increases. The observed increase in americium and europium stripping distribution ratio with increasing absorbed dose indicates the radiolytic production of organic soluble degradation compounds. These organic soluble degradation products inhibit stripping of the irradiated TRUEX solvent with dilute nitric acid. Using GC, IC and HPLC, the changes in the TRUEX solvent composition were quantified. The changes in the TRUEX solvent composition correlate will with variation in the measured extraction, scrub, and strip Am and Eu distribution ratios.Operation of the TRUEX flowsheet would require careful monitoring to ensure extraction distributions are maintained at acceptable levels. Results of flowsheet testing demonstrate that acidic degradation products are removed from the solvent. Non-acidic degradation products build-up in the process solvent but these products do not adversely impact stripping performance. Use of an aqueous complexant in the aqueous strip solution easily overcomes the adverse impacts of non-acidic degradation and maintains very efficient stripping of the TRUEX process solvent at all absorbed doses studied.

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Radiation chemical effects on radiochemistry: A review of examples important to nuclear power

Cited by 58 publications

References 125 publications

Characterization of radiolytically generated degradation products in the strip section of a TRUEX flowsheet

Characterization of radiolytically generated degradation products in the strip section of a TRUEX flowsheet

TRUEX Radiolysis Testing Using the INL Radiolysis Test Loop: FY-2012 Status Report

Summary of TRUEX Radiolysis Testing Using the INL Radiolysis Test Loop

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