Gas phase reactions of organic iodine in containment conditions

Teemu Kärkelä, J. Holm, Ari Auvinen, Riitta Zilliacus, Tuula Kajolinna, Unto Tapper, H. Glänneskog, C. Ekberg

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

7 Citations (Scopus)

Abstract

In case of a hypothetical severe accident it is very likely that iodine at least partly deposits on painted walls of a reactor containment building. Iodine may react with painted surfaces to form organic iodine species. These organic species are a possible source of volatile iodine, which may increase the fraction of releasable iodine. Therefore, it is important to study the transport of organic iodine in containment conditions. Another question is, in which form are the organic iodides transported as gaseous molecules or as aerosol particles resulting from organic iodides reacting with radiolysis products. To answer this last question methyl iodide was fed into the EXSI facility in an air mixture. In some experiments the flow contained also humidity. The reactions took place in a quartz tube heated either to 50°C, 90°C or 120°C. UV-light was used as a source of radiation to produce ozone from oxygen. A separate generator was also applied to reach higher ozone concentrations. Nucleated aerosol particles were collected on plane filters and gaseous iodine species were trapped in trapping bottles. Aerosol mass flow rate and size distribution as well as speciation of gaseous reaction products were measured with several on-line instruments. Collected aerosol particles were analysed with SEM. It was found that the formation of aerosol particles was very fast when ozone and methyl iodide were present in the facility. Even a very low concentration of ozone produced high number concentration of particles. The measured aerosol mass concentration increased with increasing temperature and ozone concentration. Because the particle diameter was quite small (<180 nm), their settling velocity is low. Therefore, iodine containing aerosols may exist in containment atmosphere for a long period of time. Part of methyl iodide was always transported through the facility regardless of experimental conditions. All ozone was consumed in the reactions when only UV-light was used as its source. With a separate generator, ozone concentration was sufficiently high to be detected at the outlet of the facility and thus enabling the study of the reaction kinetics. The transported fractions for both methyl iodide and ozone decreased with increasing reaction temperature. The main gaseous reaction products were methanol and formaldehyde. Especially at elevated temperature other reaction products, such as formic acid and methyl formate, became important as well.
Original languageEnglish
Title of host publicationProceedings of the International Congress on Advances in Nuclear Power Plants 2010, ICAPP 2010. San Diego, CA, USA, 13-17 June 2010
Subtitle of host publicationEmbedded International Topical Meeting at the 2010 ANS Annual Meeting
PublisherAmerican Nuclear Society ANS
Pages1084-1091
ISBN (Print)978-1-61738-643-5
Publication statusPublished - 2010
MoE publication typeA4 Article in a conference publication

Fingerprint

gas phase reaction
iodine
containment
iodide
ozone
aerosol
settling velocity
formic acid
temperature
reaction kinetics
formaldehyde
accident
methanol
trapping
humidity
scanning electron microscopy
quartz
filter
oxygen
product

Cite this

Kärkelä, T., Holm, J., Auvinen, A., Zilliacus, R., Kajolinna, T., Tapper, U., ... Ekberg, C. (2010). Gas phase reactions of organic iodine in containment conditions. In Proceedings of the International Congress on Advances in Nuclear Power Plants 2010, ICAPP 2010. San Diego, CA, USA, 13-17 June 2010: Embedded International Topical Meeting at the 2010 ANS Annual Meeting (pp. 1084-1091). American Nuclear Society ANS.
Kärkelä, Teemu ; Holm, J. ; Auvinen, Ari ; Zilliacus, Riitta ; Kajolinna, Tuula ; Tapper, Unto ; Glänneskog, H. ; Ekberg, C. / Gas phase reactions of organic iodine in containment conditions. Proceedings of the International Congress on Advances in Nuclear Power Plants 2010, ICAPP 2010. San Diego, CA, USA, 13-17 June 2010: Embedded International Topical Meeting at the 2010 ANS Annual Meeting. American Nuclear Society ANS, 2010. pp. 1084-1091
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title = "Gas phase reactions of organic iodine in containment conditions",
abstract = "In case of a hypothetical severe accident it is very likely that iodine at least partly deposits on painted walls of a reactor containment building. Iodine may react with painted surfaces to form organic iodine species. These organic species are a possible source of volatile iodine, which may increase the fraction of releasable iodine. Therefore, it is important to study the transport of organic iodine in containment conditions. Another question is, in which form are the organic iodides transported as gaseous molecules or as aerosol particles resulting from organic iodides reacting with radiolysis products. To answer this last question methyl iodide was fed into the EXSI facility in an air mixture. In some experiments the flow contained also humidity. The reactions took place in a quartz tube heated either to 50°C, 90°C or 120°C. UV-light was used as a source of radiation to produce ozone from oxygen. A separate generator was also applied to reach higher ozone concentrations. Nucleated aerosol particles were collected on plane filters and gaseous iodine species were trapped in trapping bottles. Aerosol mass flow rate and size distribution as well as speciation of gaseous reaction products were measured with several on-line instruments. Collected aerosol particles were analysed with SEM. It was found that the formation of aerosol particles was very fast when ozone and methyl iodide were present in the facility. Even a very low concentration of ozone produced high number concentration of particles. The measured aerosol mass concentration increased with increasing temperature and ozone concentration. Because the particle diameter was quite small (<180 nm), their settling velocity is low. Therefore, iodine containing aerosols may exist in containment atmosphere for a long period of time. Part of methyl iodide was always transported through the facility regardless of experimental conditions. All ozone was consumed in the reactions when only UV-light was used as its source. With a separate generator, ozone concentration was sufficiently high to be detected at the outlet of the facility and thus enabling the study of the reaction kinetics. The transported fractions for both methyl iodide and ozone decreased with increasing reaction temperature. The main gaseous reaction products were methanol and formaldehyde. Especially at elevated temperature other reaction products, such as formic acid and methyl formate, became important as well.",
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Kärkelä, T, Holm, J, Auvinen, A, Zilliacus, R, Kajolinna, T, Tapper, U, Glänneskog, H & Ekberg, C 2010, Gas phase reactions of organic iodine in containment conditions. in Proceedings of the International Congress on Advances in Nuclear Power Plants 2010, ICAPP 2010. San Diego, CA, USA, 13-17 June 2010: Embedded International Topical Meeting at the 2010 ANS Annual Meeting. American Nuclear Society ANS, pp. 1084-1091.

Gas phase reactions of organic iodine in containment conditions. / Kärkelä, Teemu; Holm, J.; Auvinen, Ari; Zilliacus, Riitta; Kajolinna, Tuula; Tapper, Unto; Glänneskog, H.; Ekberg, C.

Proceedings of the International Congress on Advances in Nuclear Power Plants 2010, ICAPP 2010. San Diego, CA, USA, 13-17 June 2010: Embedded International Topical Meeting at the 2010 ANS Annual Meeting. American Nuclear Society ANS, 2010. p. 1084-1091.

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

TY - GEN

T1 - Gas phase reactions of organic iodine in containment conditions

AU - Kärkelä, Teemu

AU - Holm, J.

AU - Auvinen, Ari

AU - Zilliacus, Riitta

AU - Kajolinna, Tuula

AU - Tapper, Unto

AU - Glänneskog, H.

AU - Ekberg, C.

PY - 2010

Y1 - 2010

N2 - In case of a hypothetical severe accident it is very likely that iodine at least partly deposits on painted walls of a reactor containment building. Iodine may react with painted surfaces to form organic iodine species. These organic species are a possible source of volatile iodine, which may increase the fraction of releasable iodine. Therefore, it is important to study the transport of organic iodine in containment conditions. Another question is, in which form are the organic iodides transported as gaseous molecules or as aerosol particles resulting from organic iodides reacting with radiolysis products. To answer this last question methyl iodide was fed into the EXSI facility in an air mixture. In some experiments the flow contained also humidity. The reactions took place in a quartz tube heated either to 50°C, 90°C or 120°C. UV-light was used as a source of radiation to produce ozone from oxygen. A separate generator was also applied to reach higher ozone concentrations. Nucleated aerosol particles were collected on plane filters and gaseous iodine species were trapped in trapping bottles. Aerosol mass flow rate and size distribution as well as speciation of gaseous reaction products were measured with several on-line instruments. Collected aerosol particles were analysed with SEM. It was found that the formation of aerosol particles was very fast when ozone and methyl iodide were present in the facility. Even a very low concentration of ozone produced high number concentration of particles. The measured aerosol mass concentration increased with increasing temperature and ozone concentration. Because the particle diameter was quite small (<180 nm), their settling velocity is low. Therefore, iodine containing aerosols may exist in containment atmosphere for a long period of time. Part of methyl iodide was always transported through the facility regardless of experimental conditions. All ozone was consumed in the reactions when only UV-light was used as its source. With a separate generator, ozone concentration was sufficiently high to be detected at the outlet of the facility and thus enabling the study of the reaction kinetics. The transported fractions for both methyl iodide and ozone decreased with increasing reaction temperature. The main gaseous reaction products were methanol and formaldehyde. Especially at elevated temperature other reaction products, such as formic acid and methyl formate, became important as well.

AB - In case of a hypothetical severe accident it is very likely that iodine at least partly deposits on painted walls of a reactor containment building. Iodine may react with painted surfaces to form organic iodine species. These organic species are a possible source of volatile iodine, which may increase the fraction of releasable iodine. Therefore, it is important to study the transport of organic iodine in containment conditions. Another question is, in which form are the organic iodides transported as gaseous molecules or as aerosol particles resulting from organic iodides reacting with radiolysis products. To answer this last question methyl iodide was fed into the EXSI facility in an air mixture. In some experiments the flow contained also humidity. The reactions took place in a quartz tube heated either to 50°C, 90°C or 120°C. UV-light was used as a source of radiation to produce ozone from oxygen. A separate generator was also applied to reach higher ozone concentrations. Nucleated aerosol particles were collected on plane filters and gaseous iodine species were trapped in trapping bottles. Aerosol mass flow rate and size distribution as well as speciation of gaseous reaction products were measured with several on-line instruments. Collected aerosol particles were analysed with SEM. It was found that the formation of aerosol particles was very fast when ozone and methyl iodide were present in the facility. Even a very low concentration of ozone produced high number concentration of particles. The measured aerosol mass concentration increased with increasing temperature and ozone concentration. Because the particle diameter was quite small (<180 nm), their settling velocity is low. Therefore, iodine containing aerosols may exist in containment atmosphere for a long period of time. Part of methyl iodide was always transported through the facility regardless of experimental conditions. All ozone was consumed in the reactions when only UV-light was used as its source. With a separate generator, ozone concentration was sufficiently high to be detected at the outlet of the facility and thus enabling the study of the reaction kinetics. The transported fractions for both methyl iodide and ozone decreased with increasing reaction temperature. The main gaseous reaction products were methanol and formaldehyde. Especially at elevated temperature other reaction products, such as formic acid and methyl formate, became important as well.

M3 - Conference article in proceedings

SN - 978-1-61738-643-5

SP - 1084

EP - 1091

BT - Proceedings of the International Congress on Advances in Nuclear Power Plants 2010, ICAPP 2010. San Diego, CA, USA, 13-17 June 2010

PB - American Nuclear Society ANS

ER -

Kärkelä T, Holm J, Auvinen A, Zilliacus R, Kajolinna T, Tapper U et al. Gas phase reactions of organic iodine in containment conditions. In Proceedings of the International Congress on Advances in Nuclear Power Plants 2010, ICAPP 2010. San Diego, CA, USA, 13-17 June 2010: Embedded International Topical Meeting at the 2010 ANS Annual Meeting. American Nuclear Society ANS. 2010. p. 1084-1091