Carbon 14 Distribution in Irradiated BWR Fuel Cladding and Released Carbon 14 after Aqueous Immersion of 6.5 Years

Sakuragi, Tomofumi; Yamashita, Yu; Akagi, Masaaki; Takahashi, Ryota

doi:10.1016/j.proche.2016.10.048

Cited by 5 publications

(2 citation statements)

References 19 publications

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“…The values obtained for the leaching of 14 C using both a NaOH or a H 3 PO 4 medium were above the LOQ only at the beginning of the leaching process, and it could be a consequence of 14 C distribution in the piece. According to some authors (Sakuragi et al 2016c; Ueda et al 2017), in the case of Zircaloy, 14 C specific activity in the external oxide layer that might be activated from nitrogen impurity ( 14 N(n,p) 14 C reaction) and oxygen ( 17 O(n, α) 14 C reaction) was approximately 3 times higher than that in base Zircaloy.…”

Section: Resultsmentioning

confidence: 97%

¹⁴C release from steels under aerobic conditions

et al. 2018

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Radiocarbon (14C) is a key radionuclide in the assessment of the safety of underground geological disposal facilities for radioactive wastes, and the understanding of the 14C behavior in stainless steel may lead to a re-evaluation of the near-surface repository for the disposal of wastes containing this radionuclide in high concentrations. To achieve this objective, leaching experiments were planned for two different scenarios. The first is where the leaching solution, NaOH solution of pH ca. 12 in aerobic conditions, simulates the expected conditions in a cement-based near-surface repository over long time periods. The other one uses an acid solution of 1M H3PO4, which has been proved as a high efficiency chemical removal agent of 14C in graphite. The development of both analytical methods and protocols to measure the release of 14C from the activated steel samples and the speciation in the aqueous and gaseous phase has been undertaken as part of the EC CAST (CArbon-14 Source Term) project. Analytical methods, suitable for identifying and quantifying low molecular weight organic molecules, comprise ion chromatography (IC) and gas chromatography coupled to mass spectrometry (GC-MS); they are described for aqueous and gaseous samples, respectively. In this paper the preparation of leaching experiments to measure the release of 14C and the results obtained are described.

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Section: Resultsmentioning

confidence: 97%

¹⁴C release from steels under aerobic conditions

et al. 2018

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“…Metallic components of spent nuclear fuel assembly, including Zircaloy hulls and stainless steel endpieces, are disposed in deep underground repositories after fuel reprocessing, owing to strong activation and contamination [1,2]. Several studies have investigated 14 C contents and their release from hulls [3][4][5][6][7][8] and activated steels [9][10][11][12][13]; additionally, speciation of 14 C released from activated metals has also been analyzed [14][15][16]. Regarding the current post-closure safety case [1,2], corrosion-related congruent release is a source of activated metallic wastes wherein the radionuclides are considered to be distributed homogeneously in the metal matrix.…”

Section: Introductionmentioning

confidence: 99%

Radionuclide distribution in irradiated BWR tie plate

Sakuragi¹,

Nakai

Yamamoto

et al. 2023

MRS Advances

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The contents and distribution of radionuclides in activated metallic wastes are major concerns while designing a leaching model in a safety case. This study investigated 60Co as a typical activation product in the lower tie plate (i.e., stainless steel endpiece of BWR fuel assembly) irradiated for 35.0 GWd/tHM burnup, using the imaging plate (IP) method. The activation calculations coupled with the Monte Carlo burnup and neutron transport calculation code (MCNP-BURN2) were also performed based on the burnup and operation conditions. The Co impurity content in the irradiated tie plate was obtained and used as an input to MCNP-BURN2. The IP method results showed that the intensity of photostimulated luminescence decreased with increasing distance from the top (near fuels) to bottom. This trend was consistent with that exhibited by MCNP-BURN2.Therefore, the simulations allowed us to model the three-dimensional radionuclide distribution within the tie plate. Graphical abstract Distribution of 60Co in the irradiated lower tie plate. Left shows the vertical distribution comparing the measurements and the MCNP-BURN2 results. Right represents the 3D model of 60Co distribution in the lower tie plate.

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Investigation of C-14 in the CRUD collected on the coolant filter for safety disposal of radioactive waste containing C-14 (II) – Chemical alteration of ion exchange resin under simulated condition in primary coolant of PWR

et al. 2018

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The formation mechanism and chemical form of insoluble C-14 found in PWR need to be examined in order to predict its environmental behavior after disposal. This study investigates the alteration of ion-exchange resin by heating and irradiation, because past studies indicated the ion-exchange resin may be the origin of insoluble C-14.Resin was heated at 300 °C in solution with low oxygen content to simulate the environment of PWR coolant. The sulfo group was found to detach within 8 h, and structures similar to polystyrene were remained. This is followed by detachment of H from the alkyl group, condensation reaction, and the formation of amorphous carbon-like structure. After heating for 24 and 96 h, the resin was irradiated by 60Co γ-rays in the solution. The FT-IR and TG measurements after irradiation suggested that OH and COOH groups were formed on the surface of the resin. These functional groups may be involved in reactions that finally form the amorphous carbon.In addition, the characteristics of heated and irradiated resin were compared to real insoluble-C (CRUD) sample in PWR (in Appendix).

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Carbon 14 Distribution in Irradiated BWR Fuel Cladding and Released Carbon 14 after Aqueous Immersion of 6.5 Years

Cited by 5 publications

References 19 publications

¹⁴C release from steels under aerobic conditions

¹⁴C release from steels under aerobic conditions

Radionuclide distribution in irradiated BWR tie plate

Investigation of C-14 in the CRUD collected on the coolant filter for safety disposal of radioactive waste containing C-14 (II) – Chemical alteration of ion exchange resin under simulated condition in primary coolant of PWR

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Carbon 14 Distribution in Irradiated BWR Fuel Cladding and Released Carbon 14 after Aqueous Immersion of 6.5 Years

Cited by 5 publications

References 19 publications

14C release from steels under aerobic conditions

14C release from steels under aerobic conditions

Radionuclide distribution in irradiated BWR tie plate

Investigation of C-14 in the CRUD collected on the coolant filter for safety disposal of radioactive waste containing C-14 (II) – Chemical alteration of ion exchange resin under simulated condition in primary coolant of PWR

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¹⁴C release from steels under aerobic conditions

¹⁴C release from steels under aerobic conditions