Monitoring of the Structural Integrity of Reactor Circuit (RAKEMON)

RAKEMON summary report

Ari Koskinen, Stefan Sandlin, Tarja Jäppinen, Matti Sarkimo, Mikko Vepsäläinen, Esa Leskelä

Research output: Chapter in Book/Report/Conference proceedingChapter or book articleProfessional

Abstract

Developing techniques and monitoring systems that can be used to monitor the structural integrity of the primary circuit components is quite essential. Basic pilot monitoring system was developed and constructed during 2007 and 2008. In 2009 and 2010 pilot monitoring system was further developed and monitoring tests were performed with austenitic stainless steel (316LN) pipe. The final aim was to develop measurement systems both for detection and analysis of macroscopic flaws and microscopic changes in the material that are often preceding the macroscopic failure. It is also necessary to develop inspection techniques that can be applied to reactor circuit components where the access is restricted and decreasing the reliability of inspection. The geometry and the material properties of the component to be inspected must always be considered when an ultrasonic test is planned. Ultrasonic inspection simulations for difficult geometries (nozzles) and anisotropic weld metals were done with simulation program CIVA (versions 8, 9 and 10). Fibre optical monitoring methods have been developing rapidly in recent years and nowadays there are already fibres that can resist radiation. Also methods for correcting measurement errors arising from radiation induced attenuation have been developed. The potential of using fibre optical monitoring technology in nuclear environments was evaluated in 2008. It was noticed that metal embedded fibres are in strong compression and polymer coating is eliminated. Therefore it could be possible that drift in Bragg wavelength due to volumetric changes and radiation induced hydrogen evolution from the polymer coating on the fibre could be eliminated with metal embedded fibres. Closed cracks are very dangerous because they can stay undetected for many inspection cycles due to inspection restrictions related to closed cracks. A new ultrasonic method has been developed for these closed cracks. The subharmonic ultrasonic inspection is developed at Tohoku University Japan and it seems to be very promising for these dangerous closed cracks. Steam generators are one part in the PWR type nuclear power plant that can be restricting the lifetime of the plant. Inside the steam generators there is known to be magnetite deposition on tubing and between tubes. The inspection data of steam generators contain also additional information than flaw indications. Recently eddy current data has been applied to show locations of magnetite deposition on tubing. Improvement of eddy current analysis, e.g., concerning magnetite deposition on tubing and between tubes, and flaw sizing was started in 2009 by performing literature review. Also an experimental study on detecting magnetite deposition between tubes was made in 2010. Understanding the variations in the local environmental condition facilitating iron deposition in steam generators should be improved. Pertinence of water chemistry based predictions, NDE monitoring results concerning iron deposition and plant observations and experience were studied and documented as literature reviews during 2009 and 2010.
Original languageEnglish
Title of host publicationSAFIR2010
Subtitle of host publicationThe Finnish Research Programme on Safety 2007-2010: Final Report
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Pages392-401
ISBN (Electronic)978-951-38-7690-6
ISBN (Print)978-951-38-7689-0
Publication statusPublished - 2011
MoE publication typeNot Eligible

Publication series

NameVTT Tiedotteita - Research Notes
PublisherVTT
Number2571
ISSN (Print)1235-0605
ISSN (Electronic)1455-0865

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Structural integrity
Inspection
Magnetite
Steam generators
Networks (circuits)
Monitoring
Tubing
Ultrasonics
Cracks
Fibers
Eddy currents
Radiation
Defects
Optical fibers
Metals
Iron
Coatings
Geometry
Steel pipe
Polymers

Cite this

Koskinen, A., Sandlin, S., Jäppinen, T., Sarkimo, M., Vepsäläinen, M., & Leskelä, E. (2011). Monitoring of the Structural Integrity of Reactor Circuit (RAKEMON): RAKEMON summary report. In SAFIR2010: The Finnish Research Programme on Safety 2007-2010: Final Report (pp. 392-401). Espoo: VTT Technical Research Centre of Finland. VTT Tiedotteita - Research Notes, No. 2571
Koskinen, Ari ; Sandlin, Stefan ; Jäppinen, Tarja ; Sarkimo, Matti ; Vepsäläinen, Mikko ; Leskelä, Esa. / Monitoring of the Structural Integrity of Reactor Circuit (RAKEMON) : RAKEMON summary report. SAFIR2010: The Finnish Research Programme on Safety 2007-2010: Final Report. Espoo : VTT Technical Research Centre of Finland, 2011. pp. 392-401 (VTT Tiedotteita - Research Notes; No. 2571).
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Koskinen, A, Sandlin, S, Jäppinen, T, Sarkimo, M, Vepsäläinen, M & Leskelä, E 2011, Monitoring of the Structural Integrity of Reactor Circuit (RAKEMON): RAKEMON summary report. in SAFIR2010: The Finnish Research Programme on Safety 2007-2010: Final Report. VTT Technical Research Centre of Finland, Espoo, VTT Tiedotteita - Research Notes, no. 2571, pp. 392-401.

Monitoring of the Structural Integrity of Reactor Circuit (RAKEMON) : RAKEMON summary report. / Koskinen, Ari; Sandlin, Stefan; Jäppinen, Tarja; Sarkimo, Matti; Vepsäläinen, Mikko; Leskelä, Esa.

SAFIR2010: The Finnish Research Programme on Safety 2007-2010: Final Report. Espoo : VTT Technical Research Centre of Finland, 2011. p. 392-401 (VTT Tiedotteita - Research Notes; No. 2571).

Research output: Chapter in Book/Report/Conference proceedingChapter or book articleProfessional

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T1 - Monitoring of the Structural Integrity of Reactor Circuit (RAKEMON)

T2 - RAKEMON summary report

AU - Koskinen, Ari

AU - Sandlin, Stefan

AU - Jäppinen, Tarja

AU - Sarkimo, Matti

AU - Vepsäläinen, Mikko

AU - Leskelä, Esa

PY - 2011

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N2 - Developing techniques and monitoring systems that can be used to monitor the structural integrity of the primary circuit components is quite essential. Basic pilot monitoring system was developed and constructed during 2007 and 2008. In 2009 and 2010 pilot monitoring system was further developed and monitoring tests were performed with austenitic stainless steel (316LN) pipe. The final aim was to develop measurement systems both for detection and analysis of macroscopic flaws and microscopic changes in the material that are often preceding the macroscopic failure. It is also necessary to develop inspection techniques that can be applied to reactor circuit components where the access is restricted and decreasing the reliability of inspection. The geometry and the material properties of the component to be inspected must always be considered when an ultrasonic test is planned. Ultrasonic inspection simulations for difficult geometries (nozzles) and anisotropic weld metals were done with simulation program CIVA (versions 8, 9 and 10). Fibre optical monitoring methods have been developing rapidly in recent years and nowadays there are already fibres that can resist radiation. Also methods for correcting measurement errors arising from radiation induced attenuation have been developed. The potential of using fibre optical monitoring technology in nuclear environments was evaluated in 2008. It was noticed that metal embedded fibres are in strong compression and polymer coating is eliminated. Therefore it could be possible that drift in Bragg wavelength due to volumetric changes and radiation induced hydrogen evolution from the polymer coating on the fibre could be eliminated with metal embedded fibres. Closed cracks are very dangerous because they can stay undetected for many inspection cycles due to inspection restrictions related to closed cracks. A new ultrasonic method has been developed for these closed cracks. The subharmonic ultrasonic inspection is developed at Tohoku University Japan and it seems to be very promising for these dangerous closed cracks. Steam generators are one part in the PWR type nuclear power plant that can be restricting the lifetime of the plant. Inside the steam generators there is known to be magnetite deposition on tubing and between tubes. The inspection data of steam generators contain also additional information than flaw indications. Recently eddy current data has been applied to show locations of magnetite deposition on tubing. Improvement of eddy current analysis, e.g., concerning magnetite deposition on tubing and between tubes, and flaw sizing was started in 2009 by performing literature review. Also an experimental study on detecting magnetite deposition between tubes was made in 2010. Understanding the variations in the local environmental condition facilitating iron deposition in steam generators should be improved. Pertinence of water chemistry based predictions, NDE monitoring results concerning iron deposition and plant observations and experience were studied and documented as literature reviews during 2009 and 2010.

AB - Developing techniques and monitoring systems that can be used to monitor the structural integrity of the primary circuit components is quite essential. Basic pilot monitoring system was developed and constructed during 2007 and 2008. In 2009 and 2010 pilot monitoring system was further developed and monitoring tests were performed with austenitic stainless steel (316LN) pipe. The final aim was to develop measurement systems both for detection and analysis of macroscopic flaws and microscopic changes in the material that are often preceding the macroscopic failure. It is also necessary to develop inspection techniques that can be applied to reactor circuit components where the access is restricted and decreasing the reliability of inspection. The geometry and the material properties of the component to be inspected must always be considered when an ultrasonic test is planned. Ultrasonic inspection simulations for difficult geometries (nozzles) and anisotropic weld metals were done with simulation program CIVA (versions 8, 9 and 10). Fibre optical monitoring methods have been developing rapidly in recent years and nowadays there are already fibres that can resist radiation. Also methods for correcting measurement errors arising from radiation induced attenuation have been developed. The potential of using fibre optical monitoring technology in nuclear environments was evaluated in 2008. It was noticed that metal embedded fibres are in strong compression and polymer coating is eliminated. Therefore it could be possible that drift in Bragg wavelength due to volumetric changes and radiation induced hydrogen evolution from the polymer coating on the fibre could be eliminated with metal embedded fibres. Closed cracks are very dangerous because they can stay undetected for many inspection cycles due to inspection restrictions related to closed cracks. A new ultrasonic method has been developed for these closed cracks. The subharmonic ultrasonic inspection is developed at Tohoku University Japan and it seems to be very promising for these dangerous closed cracks. Steam generators are one part in the PWR type nuclear power plant that can be restricting the lifetime of the plant. Inside the steam generators there is known to be magnetite deposition on tubing and between tubes. The inspection data of steam generators contain also additional information than flaw indications. Recently eddy current data has been applied to show locations of magnetite deposition on tubing. Improvement of eddy current analysis, e.g., concerning magnetite deposition on tubing and between tubes, and flaw sizing was started in 2009 by performing literature review. Also an experimental study on detecting magnetite deposition between tubes was made in 2010. Understanding the variations in the local environmental condition facilitating iron deposition in steam generators should be improved. Pertinence of water chemistry based predictions, NDE monitoring results concerning iron deposition and plant observations and experience were studied and documented as literature reviews during 2009 and 2010.

M3 - Chapter or book article

SN - 978-951-38-7689-0

T3 - VTT Tiedotteita - Research Notes

SP - 392

EP - 401

BT - SAFIR2010

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -

Koskinen A, Sandlin S, Jäppinen T, Sarkimo M, Vepsäläinen M, Leskelä E. Monitoring of the Structural Integrity of Reactor Circuit (RAKEMON): RAKEMON summary report. In SAFIR2010: The Finnish Research Programme on Safety 2007-2010: Final Report. Espoo: VTT Technical Research Centre of Finland. 2011. p. 392-401. (VTT Tiedotteita - Research Notes; No. 2571).