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"Comparison of welding practices in nuclear codes for PWR Equipment", Paris, 23 March 2016

The AFCEN meeting concerning the welding issues contained in various nuclear codes used in designing and construction of nuclear PWR (Pressure Water Reactor) was held in Paris on the 23 March 2016. The primary aim of the workshop was highlighting the results of the current comparative analyses and studies on competences of welders, qualification of welding technologies, quality and welding supervision basing on the requirements of the adequate sections of AFCEN and ASME codes as well as indicating the possibilities of unification of the requirements of both codes or bringing them closer, which could have a positive influence on constructing new units of nuclear power plants both from the technical and economical point of view. The meeting was attended mainly by the representatives of the French nuclear industry but also other European, Asian and American countries were present. In total over 50 representatives of welding branch working in the area of nuclear power production took part in the meeting. In turn more than a half of the lecturers were the experts collaborating with AFCEN and the rest of them represented World Nuclear Association (WNA), ASME, China Nuclear Power Engineering Co., Ltd (CNPEC) and Instytut Spawalnictwa (Institute of Welding) in Gliwice, Poland.

The meeting was opened by Claude Duval, EDF, AFCEN, Deputy Chairman of the Editorial Committee and Philippe Malouines, AREVA, AFCEN Officer for International Collaborations.

Next, the following 9 lectures were given:

  • AFCEN Involvement in International works of codes comparison - Claude Duval, EDF, AFCEN, Deputy Chairman of the Editorial Committee, France;
  • Overview of the CORDEL MCSTF - Dr Andrew Wasylyk, Project Manager, CORDEL, Great Britain;
  • Comparison of welding practices in Nuclear codes for PWR pressure equipment - Marcello Consonni, TWI, Great Britain;
  • Welding quality requirements for civil works and construction - Illustration with welding quality requirements for containment liner construction according to RCC-CW - Emmanuel Chantelat, RCC-CW WG 4 member / RCC-M WG 5 Pilot, France;
  • NF EN ISO 3834-2 requirements integrated in RCC-M 2016 - Nicolas Pierredon, Pilot RCC-M/ISO3834 Working Group, Apav, France;
  • Role of Welding coordinator in RCC-M 2016 & ISO 3834-2 - Gilles Bourgeois, Technical Manager, Institute de Soudage, Certification - IS Group, France;
  • ASME Objectives for Welding Practices Harmonization - Ryan Crane, ASME;
  • Prospects for the use of nuclear codes and standards in Poland - Jerzy Niagaj, Assoc. Prof., PhD, Instytut Spawalnictwa, Poland;
  • Experience feedback of Welding - Duan Yuangang, China Nuclear Engineering Co., Ldt., China.

The authors carried out the detailed analysis of common requirements and differences on qualifications of welders, welding procedures qualification and welding supervision/coordination in accordance with ASME and AFCEN codes. It has been stated that mutual recognition of welders qualifications is the least of the problem. Slightly more difficult would be the harmonisation of the welding procedures qualification. As one of the currently present difference, the P-number of the parent material according to ASME codes, which does not exist in European standards and AFCEN code, was mentioned. The attention was also paid on the various interpretation of the term "heat input" in the ISO standards and ASME codes: ISO standard in contrast with ASME considers the thermal efficiency factor, which may cause the significant differences in the calculation of the proper amount of heat being introduced. Moreover the principles and conditions of welding procedures qualification are also different. The biggest problems could however arise while attempting to harmonise the requirements and responsibilities within the scope of welding coordination and quality as well as qualification of production plants. In particular, the similarities and differences between AFCEN and ASME codes in the above mentioned issues will be contained in the special report, which will be available for free on the websites, including ASME website, as soon as possible.

During the meeting, the subject of using by AFCEN the qualifications acquired while certification in accordance with ISO 3834-2 was discussed. The conclusions drawn from the analysis are such that the requirements of ISO 3834-2 standard only partly fulfil the requirements of the adequate sections and chapters of AFCEN code. For instance in the ISO 3834-2 standard the role and required presence of the third party, which is a very important supervising body in the nuclear power engineering, is not very precisely specified. The specialists from France also emphasised the fact that the condition for admitting a person to supervising welding works in the nuclear power engineering is not only possession of adequate qualifications, e.g. EWE/IWE, EWT/IWT, etc. but also, and probably above all, the adequate work experience and references from the previous workplaces. Information on this issue should be checked and verified before entrusting the candidates with tasks of welding equipment and structures in nuclear power engineering.

In the end of the meeting representatives of AFCEN and ASME very positively assessed the attempts to unify both codes and declared the willingness to continue the works undertaken about 5 years ago in order to bring closer the requirements specified in codes mentioned above. It has been emphasised that defining of common issues and the most crucial differences in the approaches and requirements concerning welding is the initial and important step towards seeking and developing the common stance, which should contribute to better understanding of the parties, improving the safety of nuclear power units and collaboration on the global scale. It has been also stated that the construction of nuclear power plants in the present state of world economy has already gone beyond the borders of the countries which developed the separate nuclear technologies. Therefore, not only the construction itself but also the issues concerning maintenance and repairs are of growing importance in the context of applying the requirements of AFCEN codes and EN and EN ISO standards for repair of nuclear reactors being constructed basing on ASME codes and vice versa.

Jerzy Niagaj, PhD (DSc) Eng. Associate Professor at Instytut Spawalnictwa