full title: Training of Atomenergoremont specialists in eddy-current signal analysis and in verification and adjustment of electronic equipment, applicable to eddy-current inspection of stream generator tubes on VVER type Nuclear Power Plants
This project main objective was the improvement of the operational safety of Russian VVER NPPs through the increase of the expertise level of specialists for non-destructive testing.
The specific objectives were:
- Enabling of eddy current examination specialists to improve the reliability of inspection results and increase operation reliability and service life of steam generators.
- Enabling of electronic maintenance specialists to maintain the inspection equipment in permanent operating condition.
The project was expected to produce the following outputs:
- Task 1, 2, 3 and 4 covering training in eddy current (ET) inspection techniques applied to heat exchanger tubes, ET signal analysis, use of analysis software.
- Output: Six Russian specialists ready to analyse and interpret eddy current data acquired on VVER heat exchanger tubes.
- Task 5, 6, 7 covering training in electronic maintenance of the eddy current instrument used during inspections.
- Output: 4 engineers ready to maintain the inspection equipment in operating order.
- Task 8: Fabrication of calibration standards
- Output: 3 reference tubes with metrology report
The project activities were mainly training activities and machining of defects on reference tubes.
The target groups were:
- The four Russian NPPs operating WER 1000 reactors
- The VVER 1000 NPPs under construction in Russia
- Concern Rosenergoatom
In the first phase of the project, the two Western European (W.E.) specialists prepared the necessary material for the training courses that each of them was to deliver in Mytischi (Moscow region), Russia.
After discussions and verification of availability on both sides of the Contractor and the Project Partner, the training session dedicated to eddy current signal analysis was fixed on the 27 January 2003; the training session for electronic maintenance of the eddy current instrument was fixed on the 3 February 2003.
Five analysts (instead of the six initially scheduled in the Inception Report) attended the course on eddy current signal analysis.
Six electronic engineers (instead of four initially scheduled in the Inception Report) attended the training course on maintenance.
After having reviewed the basic principles of eddy current testing, the Russian specialists answered the questions of a level 1 test.
All the marks were above 36/40, thus showing a good level of basic knowledge.
In fact, all the attendees had already acquired experience in eddy current testing and three were currently performing signal analysis; the program initially proposed was therefore adapted to the actual level of the audience.
The instructor concentrated his work on the use of the automatic analysis software in order to solve interpretation problems posed by new types of signals, thus reaching the objectives of the session : to increase the level of expertise of the specialists and enable them to refine the interpretation of signals and increase the reliability of inspection results.
Also to increase the reliability of results, the W.E. instructor presented the complementary examinations which were in some cases necessary to clarify ambiguous results.
Reporting criteria were examined to the light of the experience gained. The instructor stressed the fact that these criteria which were initially proposed could be reviewed and adapted to the reality of the inspections.
The important aspect of calibration curves and their use for signal analysis was debated; a discrepancy between the curve stored in the software program and the curve that could actually be drawn using the signals of the in-line reference tube was pointed out.
The acceptance tests of reference tubes were described.
However, the discrepancy observed needs to be solved; the subsequent training on the calibration of the eddy current instrument was able to bring an explanation to the deviation observed.
The items included in Task 1, 2, 3 and part of Task 4 were covered.
Some items were added to the initial program:
- The general organisation of inspection teams at Intercontrole was described.
- The criteria governing the scope and periodicity of inspections in France were also described, at the request of the attendees.
- The Russian specialists also had questions concerning plugging criteria. The W.E. instructor explained the approach as applied by the French Utility and accepted by the French Regulatory Body; he stressed the fact that this delicate subject was to be discussed with the Regulator in the Country concerned.
The modifications brought to the data acquisition system by the Russian specialists were not known by the W.E. expert; the complete system was therefore re-defined so that the training session could deal with the equipment actually in operation.
The electronic boards of the eddy current instrument were then presented one by one and their maintenance described to the light of failures experienced during operation.
The topics included in Task 5 and 6 were thus covered.
Answering questions from the audience, the W.E. expert recommended calibration instruments that would be necessary to carry out effective maintenance of the eddy current instrument: digital oscilloscope, frequency generator...
Phase 1 was performed in full conformity with the Overall Plan of Operations given in the Inception Report.
The second phase of the project was performed in France.
During the second phase, the program was run as specified in the Terms of Reference. Three calibration tubes were delivered to the specialists of Atomenergoremont.
A number of actual recordings of VVER steam generator tubes were proposed to the specialists for analysis and diagnosis. The work was done using the AIDA software. The analysts were also shown the last version of the software used in France for steam generator tube inspections.
Together with their colleagues of electronic maintenance, the specialists also visited the laboratory of probe manufacturing at Intercontrole; they watched the acceptance tests for axial and rotating probes and received an explanation on the procedure for acceptance of reference tubes.
The three reference tubes manufactured in the framework of the contract were handed over to them.
On the last day, the specialists answered a written test of 40 questions and performed a practical test, in order to comply with the requirements for a level 2 qualification in eddy current testing. The results were satisfactory for the two specialists.
Two Harmonic 210 eddy current instruments were made available to the two specialists who were asked to perform a level 2 verification on each instrument, thus applying in real configuration the knowledge received during Phase 1 of the project. During the various steps of the verification procedure, the specialists described to their trainer the breakdowns that they had faced with their own instruments; the corrective actions were systematically given to them, thus ensuring that the two specialists being trained will be fully autonomous when performing the same operations by themselves in Russia.
Phase 2 was performed in conformity with the Overall Plan of Operations ; the modification of the date had no influence at all on the output.
In spite of the constraints of availability, always existing when NPP personnel is concerned by a project, the planning was realised in very close conformity with the predictions.
By involving in all 10 different specialists in the various tasks of the project, Atomenergoremont clearly showed their will to extend to the largest number of persons the benefits of the training courses.
The discussions between Russian specialists and Western European experts showed that:
- A more frequent exchange of information between them would considerably increase the sustainability of the results of this project;
- For both eddy current testing and equipment verification, the equipment available is becoming obsolete. The software version used would greatly benefit from an upgrade.
- It could happen that components out of order could be not replaced because they are no longer manufactured.
The upgrading of the existing eddy current instruments and the software for automatic analysis of eddy current data should be considered with great attention.
The investment of measuring instruments to perform adequately the verification of the eddy current instruments should also be envisaged.
All the tasks of the project were completed by the end of May 2003.