Participation in the international conference on nuclear fuel

Senior Scientist Valeriy Zuyok and Junior Scientist Mykhailo Tretyakov from NFC STE took part in the 1st International Conference on LWR Fuel Performance, Modelling and Experimental Support, held on September 14-19, 2025, in Nessebar, Bulgaria. The conference was organized by the Institute for Nuclear Research and Nuclear Energy of the Bulgarian Academy of Sciences (INRNE-BAS) with the support of Framatome, Westinghouse, Studsvik, and Kozloduy NPP. Although the title of the conference says it is the “first,” it is a continuation of the tradition of thirteen previous conferences on VVER fuel, held earlier (1994-2019) with the support of other companies.

Зуйок Валерій	Трет’яков Михайло

The conference provided a platform for sharing knowledge on fuel performance and modeling, bringing together academic research from scientific institutions, industry, and operational experience. Scientists, NPP experts, reactor designers, representatives of regulatory authorities, and suppliers discussed the latest advances in fuel technologies for light water reactors (LWRs). The conference program consisted of several sections, the main of which were:

• Fuel characteristics and operating experience.
• Improvements in fuel design and operation.
• Fuel modeling and experimental support.
• Fuel safety and quality control.
• Efficiency and spent fuel management.

About 50 reports were presented at the conference, the abstracts of which are published in the Book of Abstracts. The conference program envisaged time for detailed discussion of each report presented and exchange of views on the topics presented with nuclear industry experts from different countries.

Three reports co-authored by NFC STE specialists were presented at the conference. In the report “Approaches to Supply Ukrainian NPPs with Core Components”, specialists from Ukrainian enterprises demonstrated their unique experience in diversifying the main VVER core components (VVER-1000, VVER-440), that can be used by European NPPs. The report presents the basic aspects of safety substantiation for extending the service life of already operating RCCA, substantiation of the RCCA developed by Ukrainian enterprises, and substantiation of the absorber assembly (VVER-440) and shielding fuel assembly (VVER-440) are presented. Extending the service life of the RCCA already in operation at Ukrainian NPPs provided additional time for implementation of domestically developed RCCA. During the discussion, conference participants agreed that, with scientific support from Ukrainian research institutions, JSC “NAEK "Energoatom" is timely implementing work to meet its own needs for alternative design core components, such as RCCA (VVER-1000), absorber assembly and shielding fuel assembly (VVER-440). These components are being designed to replace the corresponding core components previously supplied exclusively from the Russian Federation.

During presentation of the report «Development of Neutron-Absorbing Materials and RCCA with Increased Performance for VVER-1000 Reactor» NFC STE specialists informed conference participants about the results, demonstrating the high level of research conducted by the NSC KIPT and the high degree of readiness of the developments related to manufacturing absorber rods and RCCA for VVER-1000 reactors with improved performance. It was proposed that, in case of need, NPPs operating VVER-1000 reactors may consider an alternative design of RCCA, which is similar to the RCCA manufactured in Russia in terms of external geometry, weight, neutron absorption efficiency, and connectivity node dimensions, but has significant differences in terms of filling with neutron-absorbing materials, namely a pellet version of absorber rod filling instead of powder.

Valeriy Zuyok during his presentation

The report «Studying the Integrity of SNF Rod Cladding at Various Stages of Dry Storage Technology Implementation» presented a methodology for predicting the behavior of SNF rod cladding made of E110 (TVZ-M/A) and ZIRLO (TVZ-W/WR) alloys under thermal effects during implementation of the dry storage technology. The calculation method proposed in this paper is based on the results of laboratory simulation tests and can be used to substantiate the integrity of fuel rod cladding in any other dry storage facilities where fuel with E110 or ZIRLO alloy cladding is stored or planned to be stored. The proposed approach was used to substantiate preservation of cladding integrity while implementing dry spent fuel storage technology at ZNPP.

Mykhailo Tretiakov during his presentation

At the end of the conference, V. Zuyok and M. Tretyakov received conference participant certificates from Professor Dimitar Tonev, Director of the Institute for Nuclear Research and Nuclear Energy at the Bulgarian Academy of Sciences (INRNE-BAS).

Valery Zuyok receiving his participant certificate from Professor Dimitar Tonev, PhD	Mikhail Tretyakov receiving his participant certificate from Professor Dimitar Tonev, PhD

The participation of NFC STE specialists in the conference allowed to demonstrate the high level of research on diversification of the main VVER core components, developments in alternative absorber rod and RCCA designs with high performance characteristics and in safe spent nuclear fuel storage, as well as to establish direct contacts with leading international companies and scientific institutions.

Conference participants having Ukrainian passports