The Impact of Alkaliphilic Biofilm Formation on the Release and Retention of Carbon Isotopes from Nuclear Reactor Graphite

Simon Rout, L. Payne, S. Walker, T. Scott, P. Heard, H. Eccles, G. Bond, Paras Shah, Paul Bills, B. R. Jackson, S. A. Boxall, Andrew Laws, Christopher Charles, S. J. Williams, Paul Humphreys

Research output: Contribution to journalArticle

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Abstract

14C is an important consideration within safety assessments for proposed geological disposal facilities for radioactive wastes, since it is capable of re-entering the biosphere through the generation of 14C bearing gases. The irradiation of graphite moderators in the UK gas-cooled nuclear power stations has led to the generation of a significant volume of 14C-containing intermediate level wastes. Some of this 14C is present as a carbonaceous deposit on channel wall surfaces. Within this study, the potential of biofilm growth upon irradiated and 13C doped graphite at alkaline pH was investigated. Complex biofilms were established on both active and simulant samples. High throughput sequencing showed the biofilms to be dominated by Alcaligenes sp at pH 9.5 and Dietzia sp at pH 11.0. Surface characterisation revealed that the biofilms were limited to growth upon the graphite surface with no penetration of the deeper porosity. Biofilm formation resulted in the generation of a low porosity surface layer without the removal or modification of the surface deposits or the release of the associated 14C/13C. Our results indicated that biofilm formation upon irradiated graphite is likely to occur at the pH values studied, without any additional release of the associated 14C.
Original languageEnglish
Article number4455
Number of pages9
JournalScientific Reports
Volume8
Issue number1
DOIs
Publication statusPublished - 13 Mar 2018

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graphite
biofilm
carbon isotope
porosity
nuclear power plant
gas
radioactive waste
biosphere
nuclear reactor
surface layer
irradiation
penetration
safety

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Rout, Simon ; Payne, L. ; Walker, S. ; Scott, T. ; Heard, P. ; Eccles, H. ; Bond, G. ; Shah, Paras ; Bills, Paul ; Jackson, B. R. ; Boxall, S. A. ; Laws, Andrew ; Charles, Christopher ; Williams, S. J. ; Humphreys, Paul. / The Impact of Alkaliphilic Biofilm Formation on the Release and Retention of Carbon Isotopes from Nuclear Reactor Graphite. In: Scientific Reports. 2018 ; Vol. 8, No. 1.
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Rout, S, Payne, L, Walker, S, Scott, T, Heard, P, Eccles, H, Bond, G, Shah, P, Bills, P, Jackson, BR, Boxall, SA, Laws, A, Charles, C, Williams, SJ & Humphreys, P 2018, 'The Impact of Alkaliphilic Biofilm Formation on the Release and Retention of Carbon Isotopes from Nuclear Reactor Graphite', Scientific Reports, vol. 8, no. 1, 4455. https://doi.org/10.1038/s41598-018-22833-5

The Impact of Alkaliphilic Biofilm Formation on the Release and Retention of Carbon Isotopes from Nuclear Reactor Graphite. / Rout, Simon; Payne, L.; Walker, S.; Scott, T.; Heard, P.; Eccles, H.; Bond, G.; Shah, Paras; Bills, Paul; Jackson, B. R.; Boxall, S. A.; Laws, Andrew; Charles, Christopher; Williams, S. J.; Humphreys, Paul.

In: Scientific Reports, Vol. 8, No. 1, 4455, 13.03.2018.

Research output: Contribution to journalArticle

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T1 - The Impact of Alkaliphilic Biofilm Formation on the Release and Retention of Carbon Isotopes from Nuclear Reactor Graphite

AU - Rout, Simon

AU - Payne, L.

AU - Walker, S.

AU - Scott, T.

AU - Heard, P.

AU - Eccles, H.

AU - Bond, G.

AU - Shah, Paras

AU - Bills, Paul

AU - Jackson, B. R.

AU - Boxall, S. A.

AU - Laws, Andrew

AU - Charles, Christopher

AU - Williams, S. J.

AU - Humphreys, Paul

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Y1 - 2018/3/13

N2 - 14C is an important consideration within safety assessments for proposed geological disposal facilities for radioactive wastes, since it is capable of re-entering the biosphere through the generation of 14C bearing gases. The irradiation of graphite moderators in the UK gas-cooled nuclear power stations has led to the generation of a significant volume of 14C-containing intermediate level wastes. Some of this 14C is present as a carbonaceous deposit on channel wall surfaces. Within this study, the potential of biofilm growth upon irradiated and 13C doped graphite at alkaline pH was investigated. Complex biofilms were established on both active and simulant samples. High throughput sequencing showed the biofilms to be dominated by Alcaligenes sp at pH 9.5 and Dietzia sp at pH 11.0. Surface characterisation revealed that the biofilms were limited to growth upon the graphite surface with no penetration of the deeper porosity. Biofilm formation resulted in the generation of a low porosity surface layer without the removal or modification of the surface deposits or the release of the associated 14C/13C. Our results indicated that biofilm formation upon irradiated graphite is likely to occur at the pH values studied, without any additional release of the associated 14C.

AB - 14C is an important consideration within safety assessments for proposed geological disposal facilities for radioactive wastes, since it is capable of re-entering the biosphere through the generation of 14C bearing gases. The irradiation of graphite moderators in the UK gas-cooled nuclear power stations has led to the generation of a significant volume of 14C-containing intermediate level wastes. Some of this 14C is present as a carbonaceous deposit on channel wall surfaces. Within this study, the potential of biofilm growth upon irradiated and 13C doped graphite at alkaline pH was investigated. Complex biofilms were established on both active and simulant samples. High throughput sequencing showed the biofilms to be dominated by Alcaligenes sp at pH 9.5 and Dietzia sp at pH 11.0. Surface characterisation revealed that the biofilms were limited to growth upon the graphite surface with no penetration of the deeper porosity. Biofilm formation resulted in the generation of a low porosity surface layer without the removal or modification of the surface deposits or the release of the associated 14C/13C. Our results indicated that biofilm formation upon irradiated graphite is likely to occur at the pH values studied, without any additional release of the associated 14C.

KW - biofilm

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