• Corrosion Science and Technology
• /
• 제17권4호
• /
• pp.147-153
• /
• 2018

Copper is used in various applications in environments favoring and enabling formation of biofilms by naturally occurring microbes. Copper is also the chosen corrosion barrier for nuclear waste in Finland. The copper canisters should have lifetimes of 100,000 years. Copper is commonly considered to be resistant to corrosion in oxygen-free water. This is an important argument for using copper as a corrosion protection in the planned canisters for spent nuclear-fuel encapsulation. However, microbial biofilm formation on metal surfaces can increase corrosion in various conditions and provide conditions where corrosion would not otherwise occur. Microbes can alter pH and redox potential, excrete corrosion-inducing metabolites, directly or indirectly reduce or oxidize the corrosion products, and form biofilms that create corrosive microenvironments. Microbial metabolites are known to initiate, facilitate, or accelerate general or localized corrosion, galvanic corrosion, and intergranular corrosion, as well as enable stress-corrosion cracking. Sulfate-reducing bacteria (SRB) are present in the repository environment. Sulfide is known to be a corrosive agent for copper. Here we show results from corrosion of copper in anoxic simulated ground water in the presence of SRB enriched from the planned disposal site.

• Corrosion Science and Technology
• /
• 제18권6호
• /
• pp.221-227
• /
• 2019

During the operation, maintenance and decommissioning of nuclear power plant radioactive contaminated waste is produced. This waste is stored in an underground repository 60-100 meters below the surface. The metallic portion of this waste comprises mostly carbon and stainless steel. A long-term field exposure showed high corrosion rates, general corrosion up to 29 ㎛ a^-1 and localized corrosion even higher. High corrosion rate is possible if microbes produce corrosive products, or alter the local microenvironment to favor corrosion. The bacterial and archaeal composition of biofilm formed on the surface of carbon steel was studied using 16S rRNA gene targeting sequencing, followed by phylogenetic analyses of the microbial community. The functional potential of the microbial communities in biofilm was studied by functional gene targeting quantitative PCR. The corrosion rate was calculated from weight loss measurements and the deposits on the surfaces were analyzed with SEM/EDS and XRD. Our results demonstrate that microbial diversity on the surface of carbon steel and their functionality is vast. Our results suggest that in these nutrient poor conditions the role of methanogenic archaea in corrosive biofilm, in addition to sulphate reducing bacteria, could be greater than previously suspected.

• 한국석유지질학회:학술대회논문집
• /
• 한국석유지질학회 1999년도 제6차 학술발표회 발표논문집
• /
• pp.40-49
• /
• 1999

The chemical compositions of natural gases and isotopic compositions of hydrocarbon gases were analyzed to characterize the properties of the gases which were found in the exploratory wells from offshore Korea, as well as those dissolved in the ground water onshore in the Pohang area. Natural gases from the offshore area mainly consisted of hydrocarbon gases $(97.98{\~}100{\%})$. The gases were composed of methane $(90{\~}96{\%})$ and minor amounts of heavier components up to $C_{6+}$ Hydrocarbon gases extracted from the groundwater in the Pohang area consisted of methane $(27{\~}376420 ppm)$ and ethane $(19{\~}127 ppm)$. The total amount of hydrocarbon gases was related to the lithology and geological factors surrounding the reservoir. The quantity of the hydrocarbon gases tended to Increase in the Tertiary reservoirs and in the reservoirs where the Tertiary formations were thickly distributed. According to the methane contents, composition of hydrocarbon gases, and stable isotope data, gases from offshore wells are identified as thermogenic in origin, generated during catagenesis stage of the oil window. On the otherhand, based on the methane content $(>99.9\%)$ and isotopic composition $(\delta^{13} C^;\; -73.1{\sim}\;-43.22{\%}_{\circ})$, it is interpretated that the gases from the Pohang area are predominantly composed of biogenic origins, which were generated by the methanogenic bacterial processes under low temperatures and anoxic conditions.

• 한국석유지질학회지
• /
• 제6권1_2
• /
• pp.37-43
• /
• 1998

포항 지역의 지하수에 녹아있는 수용성 탄화수소 가스의 지화학적 특성을 파악하기 위해서 지하수를 채취하여 지하수의 성분, 추출된 가스의 함량, 탄화수소 가스의 성분 및 탄소 동위원소 분석을 실시하였다. 지하수들로부터 추출된 총 가스의 함량은 최소 27.0 ml/l, 최대 50.1 ml/l이다. 추출된 가스 중 탄화수소 성분은 메탄 $(CH_4)$이 27 ppm에서 376,420 ppm까지 나타났고 에탄 $(C_2H_6)$ 성분도 일부 시료에서 19 ppm에서 127 ppm까지 검출되었다. 지하수로부터 추출된 총 가스의 함량은 대수층 및 주변 지질에 따른 변화는 없었던 반면, 총 탄화수소의 함량은 대수층 및 주변 지질과 관련이 있는 것으로 나타났다. 즉, 대수층이 제3기층이거나 제3기 퇴적층의 두께가 두꺼운 곳에서 시추된 공의 지하수에서 탄화 수소 가스의 함량이 높은 경향을 보인다 지하수에 녹아있는 탄화수소의 함량과 지하수의 총 고형물 (T-solids)성분이 비례하는 것으로 보아 탄화수소 성분은 제3기층의 지층수에 녹아있었던 것으로 생각한다. 지하수에서 추출된 총 탄화수소 가스 중 메탄 성분은 $99.9\%$ 이상을 차지하고, 메탄 가스의 탄소 동위원소 비 $({\delta}C^{13})$는 $-73.1\%_{\circ}$에서 $-43.22\%_{\circ}$ 까지의 범위를 나타내는 것으로 보아 포항 지역 수용성 가스는 저온, 무산소 환경에서 메탄 생성 박테리아의 작용에 의해서 생성된 생물기원 가스로 해석된다.