NDTnet 1998 Aug, Vol.3 No.8

Abstract

In-Service Inspection Systems
VVER 440 reactor pressure vessels have been inspected by Skoda Jaderne strojirenstvi remotely and automatically from the inner surface since 1982 and from the outer surface since 1986.
Two main inspection systems are in use at present:


• SKIN - system for the inspection of the reactor pressure vessels from the inner surface, designed and manufactured by Skoda Jaderne strojirenstvi.
  
• USK 213 - system for the inspection of the reactor pressure vessel from the outer surface, manufactured by NIIKIMT,USSR.

Improvements
System USK 213 was designed several years ago and it did not reach the sensitivity of testing required by codes applied for the in-service inspections of VVER reactor pressure vessels andit did not allow to store the results in digitised form for subsequent analysis and archiving.

SKIN has been used since 1992 and it has fulfilled all requirements of codes, but some of our customers demanded better parameters of ultrasonic testing and the introduction of new technique allowing more precise flaw sizing than standard pulse-echo technique.

Between 1995 and 1997 both inspection system were improved. Microplus, produced by AEA Sonomatic, Great Britain, was chosen as a new UT instrument suitable for both inspection systems. It is a modular UT instrument offering such possibilities as the storage of full A-scan and precise positioning and sizing using TOFD method.Only small changes of hardware and software were necessary to incorporate Microplus into SKIN inspection system .

Improvements of USK 213 were more complex and comprised the change of motors, position encoders, position control system, TV cameras and UT instrument. Eddy current instrument was also added to this inspection system.

Results
Both inspection systems have today the same parameters of the ultrasonic and eddy current testing and fulfil all demands of codes and our customers. The results obtained by the testing from the inner and outer surface can be compared more easily now, as the same hardware and software is used for the testing.
UT instrument Microplus proved to be a reliable instrument suitable for the automated testing in the environment of nuclear power stations.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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