Generation of Ultrafast Transient Acid Spikes in High-Temperature Water Irradiated With Low Linear Energy Transfer Radiation

Kanike, Vanaja; Meesungnoen, Jintana; Sanguanmith, Sunuchakan; Guzonas, David; Stuart, Craig R.; Jay‐Gerin, Jean‐Paul

doi:10.12943/cnr.2016.00013

Cited by 3 publications

(2 citation statements)

References 63 publications

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“…It was assumed that the dose rates were sufficiently low that there was no overlap between tracks. 35 We calculated the yields (or G-values) 36 and the concentrations of radiolytically formed H 3 O + and the corresponding pH values that prevailed in these track regions immediately after irradiation as a function of time for both low and high LET, 16,25 at ambient and elevated temperatures, 37 even under supercritical conditions. 38,39 In all cases studied, an abrupt, transient acidspike response was observed around the "native" radiation tracks.…”

Section: The Early Transitory Acidic Ph Responsementioning

confidence: 99%

Generation of ultrafast, transient, highly acidic pH spikes in the radiolysis of water at very high dose rates: relevance for FLASH radiotherapy

et al. 2022

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Monte Carlo multi-track chemistry simulations were carried out to study the effects of high dose rates on the transient yields of hydronium ions (H3O+) formed during low linear energy transfer (LET) radiolysis of both pure, deaerated and aerated liquid water at 25 °C, in the interval ~1 ps–10 μs. Our simulation model consisted of randomly irradiating water with N interactive tracks of 300-MeV incident protons (LET ~ 0.3 keV/μm), which simultaneously impact perpendicularly on the water within a circular surface. The effect of the dose rate was studied by varying N. Our calculations showed that the radiolytic formation of H3O+ causes the entire irradiated volume to temporarily become very acidic. The magnitude and duration of this abrupt “acid-spike” response depend on the value of N. It is most intense at times less than ~10–100 ns, equal to ~3.4 and 2.8 for N = 500 and 2000 (i.e., for dose rates of ~1.9 × 109 and 8.7 × 109 Gy/s, respectively). At longer times, the pH gradually increases for all N values and eventually returns to the neutral value of seven, which corresponds to the non-radiolytic, pre-irradiation concentration of H3O+. It is worth noting that these early acidic pH responses are very little dependent on the presence or absence of oxygen. Finally, given the importance of pH for many cellular functions, this study suggests that these acidic pH spikes may contribute to the normal tissue-sparing effect of FLASH radiotherapy.

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Section: The Early Transitory Acidic Ph Responsementioning

confidence: 99%

Generation of ultrafast, transient, highly acidic pH spikes in the radiolysis of water at very high dose rates: relevance for FLASH radiotherapy

et al. 2022

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“…The success of MCTS codes relies on the fairly accurate reproduction of experimental conditions. The capability of MCTS codes to simulate the temperature dependence of radiolitic yields in water has been reported in the range of 25 °C-700 °C (Hervé du Penhoat et al 2000, Plante 2011, Kanike et al 2016, Sultana et al 2020. However, to the best of our knowledge, no MCTS code has so far integrated temperature dependence for the estimation of SSB and DSB yields.…”

Section: Introductionmentioning

confidence: 99%

TOPAS-nBio simulation of temperature-dependent indirect DNA strand break yields

Ramos-Méndez¹,

Garcia-Garcia²,

Domínguez-Kondo³

et al. 2022

Phys. Med. Biol.

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Current Monte Carlo simulations of DNA damage have been reported only at ambient temperature. The aim of this work is to use TOPAS-nBio to simulate the yields of DNA single-strand breaks (SSBs) and double-strand breaks (DSBs) produced in plasmids under low-LET irradiation incorporating the effect of the temperature changes in the environment. A new feature was implemented in TOPAS-nBio to incorporate reaction rates used in the simulation of the chemical stage of water radiolysis as a function of temperature. The implemented feature was verified by simulating temperature-dependent G-values of chemical species in liquid water from 20oC to 90oC. For radiobiology applications, temperature-dependent SSB and DSB yields were calculated from 0oC to 42oC, the range of available published measured data. For that, supercoiled DNA plasmid dissolved in aerated solutions containing EDTA irradiated by Cobalt-60 gamma-rays were simulated. TOPAS-nBio well reproduced published temperature-dependent G-values in liquid water and the yields of SSB and DSB for the temperature range considered. For strand break simulations, the model shows that the yield of SSB and DSB increased linearly with the temperature at a rate of (2.94±0.17)x10–10 Gy–1Da–1 oC–1 (R2=0.99) and (0.13±0.01)x10–10 Gy–1Da–1 oC–1 (R2=0.99), respectively. The extended capability of TOPAS-nBio is a complementary tool to simulate realistic conditions for a large range of environmental temperatures, allowing refined investigations of the biological effects of radiation.

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“Acid spike” formation in the fast neutron radiolysis of supercritical water at 400 °C studied by Monte Carlo track chemistry simulations

et al. 2019

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A reliable understanding of radiolysis processes in supercritical water (SCW) cooled reactors is required to ensure optimal water chemistry control. In this perspective, Monte Carlo track chemistry simulations of the radiolysis of pure, deaerated SCW at 400 °C by 2 MeV mono-energetic neutrons were carried out as a function of water density between 0.15 and 0.6 g/cm3. The yields of hydronium ions (H3O+) formed at early time were obtained based on the G values calculated for the first three generated recoil protons. Combining our calculated G(H3O+) values with a cylindrical track model allowed us to estimate the concentrations of H3O+ and the corresponding pH values. An abrupt, transient, and highly acidic pH response (“acid spikes”) was observed at early times around the “native” fast neutron and recoil proton trajectories. This intra-track acidity was found to be strongest at times of less than a few tens to a hundred of picoseconds, depending on the value of the density considered (pH ∼ 1). At longer times, the pH gradually increased for all densities, finally reaching a constant value corresponding to the non-radiolytic, pre-irradiation concentration of H3O+, due to the autoprotolysis of water. Interestingly, the lower the density of the water, the longer the time required to reach this constant value. Because many in-core processes in nuclear reactors critically depend on the pH, the present work raises the question whether such highly acidic pH fluctuations, though local and transitory, could promote or contribute to corrosion and degradation of materials under proposed SCW-cooled reactor operating conditions.

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Generation of Ultrafast Transient Acid Spikes in High-Temperature Water Irradiated With Low Linear Energy Transfer Radiation

Cited by 3 publications

References 63 publications

Generation of ultrafast, transient, highly acidic pH spikes in the radiolysis of water at very high dose rates: relevance for FLASH radiotherapy

Generation of ultrafast, transient, highly acidic pH spikes in the radiolysis of water at very high dose rates: relevance for FLASH radiotherapy

TOPAS-nBio simulation of temperature-dependent indirect DNA strand break yields

“Acid spike” formation in the fast neutron radiolysis of supercritical water at 400 °C studied by Monte Carlo track chemistry simulations

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