Purex diluent degradation

Tallent, O.K.; Mailen, J.C.; Pannell, K.D.

doi:10.2172/5288701

Cited by 8 publications

(6 citation statements)

References 3 publications

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“…. These combine with actinide and fission product ions forming strong complexes, which decrease the stripping metal recovery and decontamination efficiencies and can sometimes cause physical problems [4]. The NPH diluent degrades to various oxidation and nitration products including long-chain nitro, nitrite, and nitroso hydrocarbons.…”

Section: Niowave 99 Mo U Utilization Processmentioning

confidence: 99%

“…The NPH diluent degrades to various oxidation and nitration products including long-chain nitro, nitrite, and nitroso hydrocarbons. Additional NPH degradation products include alcohols, unsaturated alcohols, nitro alcohols, nitro alkenes, esters, and long-chain organic acids, which tend to affect phase separation and may retain certain short-lived fission products [4,5].…”

Section: Niowave 99 Mo U Utilization Processmentioning

confidence: 99%

“…Although IT and disengagement time are related, these test methods are not necessarily redundant since the IT is determined between the solvent and aqueous Na2CO3 while the disengagement time is between the solvent and aqueous HNO3. 4 To determine the disengagement time, 5 mL of 3 M HNO3 and 5 mL of solvent were added to a small separatory funnel. The funnel was sealed and vigorously shaken for ~30 s. Two individuals independently measured the time from when shaking ceased to when they judged phase separation to be complete with stopwatches.…”

Section: Disengagement Timementioning

confidence: 99%

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Evaluation of Niowave's Proposed Solvent Washing Approach

Mills

Rudisill

2021

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Niowave, Inc., is a domestic supplier of medical and industrial isotopes from uranium (U) and radium (Ra). The company has recently entered into a cooperative agreement with the U.S. Department of Energy's National Nuclear Security Administration (NNSA) and plans to deploy a superconducting electron accelerator (LINAC) to fission U for molybdenum-99 ( 99 Mo) production without the need for a nuclear reactor or highly enriched uranium (HEU). NNSA provided funding to the Savannah River National Laboratory (SRNL) to support Niowave in this effort.Niowave will chemically process the irradiated material for recovery and purification of valuable isotopes, beginning with the dissolution of targets in nitric acid (HNO3). A modified Plutonium Uranium Reduction Extraction (PUREX) process will be implemented for the recovery of U. The PUREX process utilizes a tributyl phosphate (TBP) in normal paraffin hydrocarbon (NPH) solvent which, when contacted with the nitric acid feed, extracts actinides into the organic phase. Ionizing radiation and nitric acid cause degradation of both the TBP and NPH. The principal degradation products of TBP are dibutyl phosphate (DBP) and monobutyl phosphate (MBP), which decrease U stripping efficiencies. NPH degradation products include a variety of oxidation and nitration products, which tend to affect phase separation and may retain certain short-lived fission products. A solvent washing process has been proposed to treat the degraded solvent by contacting it with 4 wt% sodium carbonate (Na2CO3) followed by contact with 0.1 M HNO3 to neutralize residual alkalinity. The carbonate wash is effective at removing DBP and MBP but does not remove long chain degradation products derived from the solvent. SRNL evaluated the application of the solvent washing process for Niowave at the proposed solvent:carbonate volume ratio (O:A) of 1:1.14 and with a reduced proportion of carbonate at an O:A ratio of 1:0.5. To do so, solvent was contacted with nitric acid and irradiated to the anticipated single pass radiation dose of 394 gray (Gy) and 10x and 100x the anticipated dose to demonstrate the impact of multiple recycles on the solvent quality. The solvent of all three doses was washed at the proposed O:A ratio and alternate O:A ratio of 1:0.5. The quality of the solvent was evaluated based on recommendations for similar processes at the Savannah River Site including DBP concentration, interfacial tension (IT), and disengagement time. Revision viii

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Section: Niowave 99 Mo U Utilization Processmentioning

confidence: 99%

Section: Niowave 99 Mo U Utilization Processmentioning

confidence: 99%

Section: Disengagement Timementioning

confidence: 99%

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Evaluation of Niowave's Proposed Solvent Washing Approach

Mills

Rudisill

2021

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“…Khaikin has suggested that HDBP is a stable product resulting from reaction of dissolved oxygen and the TBP radical [9]. The degradation has also been investigated as a function of diluent [12][13][14][15][16], water and nitric acid [17][18][19][20][21], temperature [22,23], and metal ions [20,24,25].…”

Section: Introductionmentioning

confidence: 99%

Studies on Pu238 induced alpha radiolysis of the solvent TBP

Gao

Zheng

Cao

et al. 2014

J Radioanal Nucl Chem

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Radiolysis and degradation of a 30 % volume mixture of TBP in n-dodecane has been studied by means of alpha radiation from Pu 238 . Radiolysis effects are quantitatively estimated by the percent of Pu 238 retained in the irradiated organic phase after the washing procedure. The effects of radiation dose, nitric acid concentration, and the presence of UO 2 2? and Zr 4? , have been investigated. The results indicate that Zr 4? accelerates the alpha-particle degradation of the organic phase, and that both UO 2 2? and Pu 4? complex with the degradation products formed by the absorbed radiation.

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“…The actinides, U and Pu, from the HNO 3 medium, are then preferentially extracted into an organic medium containing 30% (V=V) solution of tri-n-butyl phosphate (TBP) in n-dodecane (n-DD). Incidentally, both TBP and n-DD undergo chemical and radiolytic degradation during fuel reprocessing (1)(2)(3). The accumulations of these products are detrimental to the reprocessing and hence monitoring the organic phase for the accumulation of these degradation products is therefore essential.…”

Section: Introductionmentioning

confidence: 99%