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Ultrasonic inspection of the PZR spray nozzle bend

Design, manufacturing, fine-tuning, qualification and implementation of an ultrasonic examination process to inspect the pressurizer spray nozzle bends in EDF PWR power plants

Ultrasonic inspection of the PZR spray nozzle bend


As part of its defence-in-depth actions, EDF promised the ASN (French Nuclear Safety Authority) to conduct an exploratory inspection of the bend zone of Pressurizer (PZR) spray nozzles in the 900MW, 1300MW and 1450MW PWR units. Although there has never been any mention of a defect in this zone in international feedback reports, EDF’s engineering department has identified this 35mm radius curved section as being sensitive, saying that it could contain indications revealing potential safety issues for the component.


EDF missioned Onet Technologies to implement this ultrasonic examination process. The process requires a high level of technical expertise since the inspection has to be carried out from the curved outer surface of the part, through its carbon steel wall which can reach up to 90 mm in thickness. EDF also placed its trust in Onet Technologies because of its recognized proficiency in working in restricted environments. Because of the radiological constraints, the process needs to be automated and remotely piloted from an ALARA zone

Service provided

The services provided by Onet Technologies comprise:

  1. Mechanic and ultrasonic design studies, numerical simulations using CIVA in order to draft the technical procurement specifications of the automated carrier and the ultrasonic transducers
  2. Construction of 3D models of the PZR dome and the spray line piping in order to position where indications were taken during the data analysis
  3. Compilation of the technical justification file, indicating the 36 influential variables, their range of variance and their impact on process performance
  4. Performance demonstration trials on a representation model with electro-eroded defects
  5. Drafting of the Works Performance reports for the on-site operations
  6. Training of 8 operators
  7. Services performed on the 4 oldest PZR and on 1 PZR with high sulphur rate

Core Competencies

  • In-Service Inspection Rules for Mechanical Components of PWR Nuclear Islands (RSE-M)
  • Ultrasound standards NF EN 12668, NF EN ISO 11666, NF EN ISO 2400, NF EN ISO 9712, NF EN 1300
  • CIVA software for NDE digital simulation
  • Ultravision 3D ultrasonic analysis software
  • Deployment on IFS equipment under high irradiation


Country: France
Client: EDF UTO

Project Details:

  • Project duration: 5 years, from 2012 to 2017.
  • Process design and qualification from 2012 to 2014.
  • Site operations from 2015 to 2017
  • 3 project managers specialised in project coordination and management, mechanical design and ultrasonic technology


36, boulevard de l’Océan - CS 20280
13258 Marseille Cedex 9 - France
Phone: +33 (0)4 91 29 18 10
Fax: +33 (0)4 91 29 18 58

ONET SA - RCS B 059 801 324 Marseille


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