Experience on the ultrasonic inspection of control rod nozzles of reactor pressure vessel

Pentti Kauppinen, Harri Jeskanen, Raimo Paussu, Bernhard Elsing

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

Abstract

The nozzles of control rods to the reactor pressure vessel closure head have caused serious problems worldwide. In the case of VVER440-reactors the special area of interest is to assure the tightness of the austenitic corrosion protection tube placed inside the control rod nozzle. If leakage through the weld closing the protection tube is occurring boric water can penetrate in the narrow air gap between the ferritic nozzle and the tube leading to corrosion damages in the ferritic nozzle. The water can also cause buckling of the tube inwards in the amount that disturbs or even stops the operation of control rod drive mechanism. VTT has developed a special ultrasonic technique to monitor the condition of control rod nozzles during the shutdown period of the plant. The technique has been applied during several years and the results of inspection have led to repair of some nozzles. The principle of the technique as well as its limitations are presented and discussed in this presentation.
Original languageEnglish
Title of host publicationBALTICA VII - Life Management and Maintenance for Power Plants. Vol. 2
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Pages235-241
ISBN (Electronic)978-951-38-6318-0
ISBN (Print)978-951-38-6317-3
Publication statusPublished - 2007
MoE publication typeB3 Non-refereed article in conference proceedings
EventBALTICA VII - International Conference on Life Management and Main-tenance for Power Plants - Helsinki-Stockholm, Finland
Duration: 12 Jun 200714 Jun 2007

Publication series

SeriesVTT Symposium
Number247
ISSN0357-9387

Conference

ConferenceBALTICA VII - International Conference on Life Management and Main-tenance for Power Plants
CountryFinland
CityHelsinki-Stockholm
Period12/06/0714/06/07

Fingerprint

Control rods
Pressure vessels
Nozzles
Inspection
Ultrasonics
Container closures
Corrosion protection
Buckling
Water
Welds
Repair
Corrosion
Air

Cite this

Kauppinen, P., Jeskanen, H., Paussu, R., & Elsing, B. (2007). Experience on the ultrasonic inspection of control rod nozzles of reactor pressure vessel. In BALTICA VII - Life Management and Maintenance for Power Plants. Vol. 2 (pp. 235-241). Espoo: VTT Technical Research Centre of Finland. VTT Symposium, No. 247
Kauppinen, Pentti ; Jeskanen, Harri ; Paussu, Raimo ; Elsing, Bernhard. / Experience on the ultrasonic inspection of control rod nozzles of reactor pressure vessel. BALTICA VII - Life Management and Maintenance for Power Plants. Vol. 2. Espoo : VTT Technical Research Centre of Finland, 2007. pp. 235-241 (VTT Symposium; No. 247).
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abstract = "The nozzles of control rods to the reactor pressure vessel closure head have caused serious problems worldwide. In the case of VVER440-reactors the special area of interest is to assure the tightness of the austenitic corrosion protection tube placed inside the control rod nozzle. If leakage through the weld closing the protection tube is occurring boric water can penetrate in the narrow air gap between the ferritic nozzle and the tube leading to corrosion damages in the ferritic nozzle. The water can also cause buckling of the tube inwards in the amount that disturbs or even stops the operation of control rod drive mechanism. VTT has developed a special ultrasonic technique to monitor the condition of control rod nozzles during the shutdown period of the plant. The technique has been applied during several years and the results of inspection have led to repair of some nozzles. The principle of the technique as well as its limitations are presented and discussed in this presentation.",
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Kauppinen, P, Jeskanen, H, Paussu, R & Elsing, B 2007, Experience on the ultrasonic inspection of control rod nozzles of reactor pressure vessel. in BALTICA VII - Life Management and Maintenance for Power Plants. Vol. 2. VTT Technical Research Centre of Finland, Espoo, VTT Symposium, no. 247, pp. 235-241, BALTICA VII - International Conference on Life Management and Main-tenance for Power Plants, Helsinki-Stockholm, Finland, 12/06/07.

Experience on the ultrasonic inspection of control rod nozzles of reactor pressure vessel. / Kauppinen, Pentti; Jeskanen, Harri; Paussu, Raimo; Elsing, Bernhard.

BALTICA VII - Life Management and Maintenance for Power Plants. Vol. 2. Espoo : VTT Technical Research Centre of Finland, 2007. p. 235-241 (VTT Symposium; No. 247).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

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AB - The nozzles of control rods to the reactor pressure vessel closure head have caused serious problems worldwide. In the case of VVER440-reactors the special area of interest is to assure the tightness of the austenitic corrosion protection tube placed inside the control rod nozzle. If leakage through the weld closing the protection tube is occurring boric water can penetrate in the narrow air gap between the ferritic nozzle and the tube leading to corrosion damages in the ferritic nozzle. The water can also cause buckling of the tube inwards in the amount that disturbs or even stops the operation of control rod drive mechanism. VTT has developed a special ultrasonic technique to monitor the condition of control rod nozzles during the shutdown period of the plant. The technique has been applied during several years and the results of inspection have led to repair of some nozzles. The principle of the technique as well as its limitations are presented and discussed in this presentation.

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Kauppinen P, Jeskanen H, Paussu R, Elsing B. Experience on the ultrasonic inspection of control rod nozzles of reactor pressure vessel. In BALTICA VII - Life Management and Maintenance for Power Plants. Vol. 2. Espoo: VTT Technical Research Centre of Finland. 2007. p. 235-241. (VTT Symposium; No. 247).