Structural Integrity and NDE Reliability II

Transcription

1 Structural Integrity and NDE Reliability II Preparing for EPR TM Reactor Vessel Inspection J. Laube, AREVA NDE Solutions / intelligendt, Germany Y. Bouveret, AREVA NDE Solutions / Intercontrole, France S.W. Glass, AREVA NDE Solutions / NETEC, France J.M. Tchilian, AREVA Products & Technologies, France ABSTRACT The EPRTM reactor pressure vessels for France and Finland have identical geometry and material. The approach for Pre-Service-Inspection (PSI) and In-Service Inspection (ISI) with associated qualification works however must be adapted to the specific requirements of the country for which the plant is licensed. Therefore, neither the inspection techniques nor the qualification tasks are identical. General methodology and terms for qualification of inspection systems are described within ENIQ Guideline EUR EN which was established by electric utility experts from EdF France, TVO Finland and other European nations. The specific requirements for the two first nations to host AREVA s EPRTM`s are described within the following guidelines: YVL 3.8 for Finland RSE-M for France This presentation deals with the requirements and differences for the EPR TM`s in Flamanville and Olkiluoto specifically addressing: Qualification processes for Non Destructive Examination (NDE) techniques AREVA s NDE technologies for mechanized RPV inspection AREVA s robotic technologies for RPV inspection Differences and the similarities of the Finnish and French approaches are highlighted and explained taking into account the development of nuclear energy and safety regulation in both countries. This presentation shows, how AREVA s advanced RPV inspection technology from the US, France, and Germany has been adapted and optimized to fulfill the specific (different) requirements of our customers in France and Finland. FIRST EPR TM PLANTS LOCATION AT FLAMANVILLE AND OLKILUOTO AREVA is well underway with fabrication and errection of the first two EPRs TM in Flamanville, France and Olkiluoto, Finland. (Figure 1) The EPR is a large 4-loope pressurized water reactor (PWR) design with an electrical output of approximately 1600 MW.

2 Figure 1 - EPR TM site location EPR TM QUALIFICATION FOR (PSI) AND (ISI) The welds and specific sensitive areas of the nuclear steam supply primary circuit must be monitored regularly by non-destructive examination to: verify structural integrity and plant safety, ensure efficiency of investment. Safe, reliable, and efficient operation are assured by a structured qualification program. The Qualification requirements are delineated in the codes and standards of the French and Finish national nuclear regulatory authorities. Although the general approach and end goal of the two regulations are similar, the details are quite different. EPR TM QUALIFICATION OBJECTIVES AND IMPLEMENTATION FOR PSI/ISI Qualification tasks include: Demonstration of Inspection techniques Test and certification of operational specialists/analysts Demonstration of delivery tooling Qualification is carried out in accordance with the ENIQ process. France and Finland each perform qualifications in accordance with guideline EUR EN. The steps for Qualification are shown in Figure 2. Figure 2 - ENIQ Process Modules and execution sequence

3 Implementation directives fall under the national regulations below. France RSEM code Finland YVL 3.8 MAIN STAKEHOLDERS IN THE QUALIFICATION PROCESS The Licensee is responsible for delivering the qualification file to the Radiation and Nuclear Safety Authority for approval. The Qualification Body/Commission is responsible for establishing the qualification procedure, managing the qualification work and assembling the qualification file. The Inspection Body is responsible for carrying out the practical qualification work in association with the Qualification Body. RPV inspection qualification entities for EPR TM qualification in France and Finland For the EPR TM in France, the utility-edf is the licensee and the builder of the plant. EdF also manages PSI qualifications and implementation: EdF has subcontracted all qualification work to AREVA. EdF interfaces and coordinates with the French Qualification Commission. EdF supervises the qualification work. EdF delivers the qualification file to the French Radiation and Nuclear Safety Authority (ASN). For the EPR TM in Finland, the utility TVO is the licensee. The licensee has granted a turnkey contract to AREVA including PSI and all qualification tasks for the main primary components. Under this contract, AREVA and TVO manage activities as follows: AREVA performs PSI qualifications and implementation. AREVA interfaces and coordinates with the Finnish Qualification Body. AREVA supervises qualification and delivers the qualification file to TVO. TVO delivers the qualification file to the Finnish Radiation and Nuclear Safety Authority (STUK). QUALIFICATION AND PSI COMPARISON IN FRANCE AND FINLAND The PSI and ISI program as shown in Figure 3 is mostly identical but with the exception that the RSEM code does require RT on both safe-end welds in addition to the UT examination.

4 Figure 3 - inspection program INSPECTION TARGETS In France, EdF has a mature program for PWR qualifications and inspections on vessels not substantially smaller than the Flamanville vessel. This EPR TM RPV qualification is treated as an extension of the existing fleet s qualification. Conventional reflectors are used as references for detection sensitivity and sizing verification. These reference reflectors are then compared to model flaws, known in-service flaw indications, and a substantial set of fabricated flaws to verify inspection performance. In Finland, the program is viewed as a complete qualification. Finland has no other large PWRs on which to base their qualification so worst case realistic reflectors are used to establish the sensitivity level for detection and sizing of indication. These reflectors include both mechanical fatigue cracks and EDM notches. Time of flight methods are used for sizing to determine the boundaries of an indication. Figure 4 - inspection targets

5 NDT TECHNIQUE TECHNICAL JUSTIFICATION Essential parameters and their tolerances that can influence inspection performance are identified and considered within the technical justification document. Essential parameters include: Deviation between test block geometries and on-site geometries (e.g. surfaces,material, wall thickness, etc.) Type of defect (e.g. shape, surface, orientation, etc.) Sensor characteristics (e.g. frequency, size of sensor, etc.) UT equipment characteristics (cables, bandwidth of electronic components, etc.) UT instrument parameters (sampling rate, pulse shape, data compression, etc.) Delivery tool parameters (accuracy, repeatability, etc.) Parametric studies, practical trials and also 3D modeling are performed to determine influence and tolerances. The general approach in France and Finland is similar. France: The existing technical justifications that have been extensively validated for French PWR RPV are extended to FA3 RPV specifics. Finland: The technical justifications for the OL3 RPV consider the specific input information Within the framework of Finnish guidelines and recommendations. INSPECTION PROCEDURE The inspection procedure describes the complete process for preparation, execution, and documentation of the inspection utilizing the qualified tool and process. The inspection procedure is specific for the tools and techniques applied in France and Finland. Following the qualified inspection procedure assures comparable inspection results during pre-service- and in-service inspections. PRACTICAL TRIALS ON OPEN TEST BLOCKS For the Flamanville 3 RPV qualification, a number of test blocks coupled with 3D modeling software were applied. Open full-scale test blocks were compared to real component with machined reflectors for specific areas of the vessel representing the greatest inspection challenges and likely locations for flaws including: Nozzle-to-shell welds Dissimilar Metal Welds (DMWs) Flange threads The test-block data were coupled with 3D CIVA computer models to extrapolate between testblock weld configuration and similar on-vesel weld configurations. For the Olkiluoto-3 qualification, 7 different open full-scale test blocks were fabricated with a plurality of mechanical fatigue cracks were fabricated to cover the following geometries (Figure 5) Nozzle-to-shell Nozzle inner radius Shell large wall size Shell small wall size Safe-end weld

6 A step-by-step verification of the inspection procedure in front of the Qualification Body was performed for both the Flamanville and the Olkiluoto project to assure: Delectability of critical flaws Sizing accuracy Reliability, repeatability, and robustness of the process Figure 5 - open 1:1 scale test blocks REQUIREMENTS FOR SPECIFIC QUALIFICATION OF NDT PERSONNEL The basic requirements for NDT personnel are the same for France and Finland: Certification in accordance with EN 473 for the applied technique Training on specific procedures developed for the project France, the inspection company supervises the qualification on the latest applicable procedure for data analysts on data sets acquired during previous RPV inspections. Finland: each data analyst must prove that he is able to apply the OL3 inspection procedures to datasets acquired on 5 different OL3-specific blind test blocks. The examination is managed by the Finnish Qualification Body for: Detection Sizing No false calls are allowed

7 CERTIFICATION FOR DATA ANALYSTS AND OTHER INSPECTION PERSONNEL France: The EN 473 certification is managed by COFREND CIFM. The certification is valid for 10 years with continuous work experience. The RV PSI/ISI with the MIS manipulator AREVA s NDE procedures are managed by COFREND CENE. There is no specific formal certification only applicable to the Flamanville reactor. Finland: The EN 473 certification applicable to UT analysts is managed by DGzfP or another outside agency. The certification is valid for 10 years with continuous work experience. SAPHIRplus acquisition inspector authorizations are managed by the inspection company. The certificate has unlimited validity with proof of continuous experience. OL3-specific certification is managed by SFS Inspecta - the Finnish Qualification Body and is valid for 5 years. This certification expires after 5 years and must be renewed with a new blind test using stored data from the blind test-block sample set. UT INSPECTION TRANSDUCER CONFIGURATIONS AREVA meets the specific requirements for both EPR TM projects. In France, the traditional method used for more than 20 years is immersion focused probes. In Finland, Phased Array Contact techniques are applied for all regions of the vessel. In both cases, the AREVA built SAPHIR plus UT instrument is used but the configuration is different (more channels and Phased ARRAY features for OL-3). Figure 6 - inspection technique for France and Finland ROBOTS: The most striking outwardly visible difference between the two projects is the different robot. The MIS is the massive French robot designed for immersion UT plus nozzle RT. This robot concept has been used for hundreds of vessel examinations in France and other countries around the world. The TWS robot is AREVA s newest RPV tool. It has been deployed since Two TWS can operate in parallel to shorten vessel occupation time. Both machines will meet the accuracy requirements for flaw sizing and positioning as required in the specific codes. Vessel occupation time for EPR TM UT scope in either case is projected < 4 days.

8 Figure 7 - RPV inspection robots

9 EPR TM REACTOR VESSEL QUALIFICATION SUMMARY AND CONCLUSION Guideline EUR EN for the qualification of RPV inspection systems and specialists is implemented in both France and Finland. France - EDF 58 operating PWR nuclear power plants, with start of operation between Guideline EUR EN is implemented via the RSE-M rules Existing NDT qualifications for large PWR vessels have been extended to the FA3 EPR TM vessel geometry primarily by technical justification Finland - TVO 2 operating BWR nuclear power plants, with start of operation between EUR 1799 EN implemented via code YVL 3.8 The OL3 EPR TM RPV geometry is quite different from that of the BWR RPV, resulting in full qualification in line with national requirements Qualification content and approach are determined by: Specific national rules and guidelines - and their application by the licensee Available qualification files with input information close to the actual qualification task Despite the common ENIQ guideline and essentially identical vessel designs, regulatory requirements and licensee experience has resulted in substantially different programs, NDE techniques, and robotic delivery tools for the French and Finish EPR. Successful qualifications are underway and are substantially complete in preparation for 2011/2012 on-site PSIs.