Comparison of different target material options for the European Spallation Source based on certain aspects related to the final disposal

Kokai, Z.; Török, Szabina; Zagyvai, P.; Kiselev, D.; Moormann, R.; Börcsök, Endre; Zanini, L.; Takibayev, A.; Muhrer, G.; Bevilacqua, Riccardo; Janik, József

doi:10.1016/j.nimb.2017.11.027

Cited by 9 publications

(12 citation statements)

References 18 publications

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“…The FLUKA code was used for calculations, as it is suitable for calculations of particle transport and interactions with matter using the Monte Carlo method 17 , 18 . We obtained about a factor of 2 higher absolute values of 148 Gd in comparison with other authors 21 , 22 , and these differences can be attributed to differences in spallation and nuclide evaporation models. Unfortunately, there are no experimental data yet to evaluate which of the predictions is more accurate regarding absolute values.…”

Section: Theoretical Outline and Methodscontrasting

confidence: 45%

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Internal dose assessment of 148Gd using isotope ratios of gamma-emitting 146Gd or 153Gd in accidently released spallation target particles

Rääf

Barkauskas

Stenström

et al. 2020

Sci Rep

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The pure alpha emitter 148Gd may have a significant radiological impact in terms of internal dose to exposed humans in case of accidental releases from a spallation source using a tungsten target, such as the one to be used in the European Spallation Source (ESS). In this work we aim to present an approach to indirectly estimate the whole-body burden of 148Gd and the associated committed effective dose in exposed humans, by means of high-resolution gamma spectrometry of the gamma-emitting radiogadolinium isotopes 146Gd and 153Gd that are accompanied by 148Gd generated from the operation of the tungsten target. Theoretical minimum detectable whole-body activity (MDA) and associated internal doses from 148Gd are calculated using a combination of existing biokinetic models and recent computer simulation studies on the generated isotope ratios of 146Gd/148Gd and 153Gd/148Gd in the ESS target. Of the two gamma-emitting gadolinium isotopes, 146Gd is initially the most sensitive indicator of the presence of 148Gd if whole-body counting is performed within a month after the release, using the twin photo peaks of 146Gd centered at 115.4 keV (MDA < 1 Bq for ingested 148Gd, and < 25 Bq for inhaled 148Gd). The corresponding minimum detectable committed effective doses will be less than 1 µSv for ingested 148Gd, but substantially higher for inhaled 148Gd (up to 0.3 mSv), depending on operation time of the target prior to the release. However, a few months after an atmospheric release, 153Gd becomes a much more sensitive indicator of body burdens of 148Gd, with a minimum detectable committed effective doses ranging from 18 to 77 µSv for chronic ingestion and between 0.65 to 2.7 mSv for acute inhalation in connection to the release. The main issue with this indirect method for 148Gd internal dose estimation, is whether the primary photon peaks from 146 and 153Gd can be detected undisturbed. Preliminary simulations show that nuclides such as 182Ta may potentially create perturbations that could impair this evaluation method, and which impact needs to be further studied in future safety assessments of accidental target releases.

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Section: Theoretical Outline and Methodscontrasting

confidence: 45%

“…Left: Whole body. Right: Lung model taken from ICRP 12 using f b = 0.07, f r = 0.5, s b = 0.021 d −1 , s s = 0.002 d −1 , and s r = 0.3 d −1 . Parameters are further explained in ICRP 130 24 .…”

Section: Resultsmentioning

confidence: 99%

Internal dose assessment of 148Gd using isotope ratios of gamma-emitting 146Gd or 153Gd in accidently released spallation target particles

Rääf

Barkauskas

Stenström

et al. 2020

Sci Rep

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“…A liquid material can easily be mixed and thus ensures a good heat distribution, while at the same time an embrittlement of the target material (as in solid materials) is avoided. Mercury is thus used in spallation targets in the Japan Spallation Neutron Source (JSNS), Tōkai, Japan, and in the Spallation Neutron Source (SNS), Oak Ridge, Tennessee [28][29][30][31][32][33][34][35]. To the best of our knowledge, no final disposal route for the mercury from this process has been approved.…”

Section: Introductionmentioning

confidence: 99%

Gamma-spectrometric measurement procedure for a clearance concept of radioactively contaminated mercury from nuclear facilities

Klass

Ritz

Hirsch

et al. 2021

J Radioanal Nucl Chem

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Radioactive mercury waste constitutes a significant challenge, as no approved disposal concept yet exists for such waste in Germany. This work describes a decontamination and measurement procedure for a possible clearance of mercury from nuclear facilities and release into reuse or conventional hazardous waste disposal to reduce the amount of mercury in a nuclear repository. The measurement setup and procedure were developed and evaluated including Monte-Carlo N-Particle® Transport Code (MCNP® and Monte Carlo N-Particle® are registered trademarks owned by Los Alamos National Security, LLC, manager and operator of Los Alamos National Laboratory, (Werner 2018, Werner 2017)), simulations to ensure conservative assumptions during the measurements. Results from decontaminated mercury samples show that a clearance pursuant to the German regulations would be feasible.

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“…Finally, W was chosen as the best option based on its waste index. 2 The knowledge of the radionuclide inventory induced during long-term irradiation (up to 5 years) of such a target is a precondition for the risk assessment to ensure a safe operation and storage of disposed target after shutdown as well as to develop emergency scenarios in case of a severe accident. An overview of the radionuclides with half-lives > 10 h expected to be produced in the ESS target is reported in ref 3.…”

mentioning

confidence: 99%

“…Previously, different target materials were considered for ESS, such as W, Hg, lead–bismuth eutectic (LBE), and Pb-17% Au eutectic. Finally, W was chosen as the best option based on its waste index …”

mentioning

confidence: 99%

Radiochemical Determination of Long-Lived Radionuclides in Proton-Irradiated Heavy Metal Targets: Part II Tungsten

et al. 2021

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In this study, proton-irradiated tungsten targets, up to 2.6 GeV, were investigated for the purpose of the experimental cross-section measurements. Radiochemical separation methods were applied to isolate the residual long-lived alpha-emitters 148Gd, 154Dy, and 146Sm and the beta-emitters 129I and 36Cl from proton-irradiated tungsten targets. The molecular plating technique has been applied to prepare 148Gd, 154Dy, and 146Sm samples for alpha-spectrometry. Production cross-sections of 129I and 36Cl were determined by means of accelerator mass spectrometry. The results are compared with theoretical predictions, obtained with the INCL++–ABLA07 codes, showing good agreement for 36Cl and 148Gd, while a factor of 4 difference was observed for 154Dy, similar to the results obtained for tantalum targets.

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Comparison of different target material options for the European Spallation Source based on certain aspects related to the final disposal

Cited by 9 publications

References 18 publications

Internal dose assessment of 148Gd using isotope ratios of gamma-emitting 146Gd or 153Gd in accidently released spallation target particles

Internal dose assessment of 148Gd using isotope ratios of gamma-emitting 146Gd or 153Gd in accidently released spallation target particles

Gamma-spectrometric measurement procedure for a clearance concept of radioactively contaminated mercury from nuclear facilities

Radiochemical Determination of Long-Lived Radionuclides in Proton-Irradiated Heavy Metal Targets: Part II Tungsten

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