UK/TS/28 is a 2+2 project in which EU Technical Support Organisations support the Ukrainian Nuclear Safety Authority (SNRCU) in its activities on licensing related assessments of EU financed improvement measures in Zaporozhye NPP.

The project mainly concerned the technical review of three industrial modification projects U1.03/99A, U1.03/99B and U1.03/99C.

Task 1: Steam Generators safety valves replacement – Units 1 to 6 (U1.03/99A)

The EU experts reviewed the Prelimary Safety Assessment Report (PSAR) and the Final Safety Analysis Report (FSAR) and the results of the test program after mounting of the equipment. They pointed out that answers to the most important questions raised in reviewing the PSAR, concerning the strength calculations in the pipe lines and I&C, did not received a satisfactory answer in the FSAR and therefore remain open.

ENERGOATOM stated that the comments of the experts would be taken into account in the framework of a new project of modernization on another NPP.

The experts recommended to SNRCU to give the NPP a conditional agreement concerning the mounting and the commissioning of the new safety valves.

Task 2: Improvement of Pressuriser safety valves - units 1 to 4 (U1.03/99B)

The experts reviewed the PSAR and the QA programme and recommended to SNRCU to give a conditional agreement to the NPP concerning the mounting and commissioning of the improvements of the pressurizer safety valves.

Task 3: Replacement of feedwater control valves – unit 1 (U1.03/99C)

The experts reviewed Technical Specifications, Test Program, PSAR, FSAR, decision on mounting, decision on commissioning and the results of the trial operation.

The review demonstrates that the equipment was compliant. Several comments in the licensing process for the Steam Generator Feedwater Control Valves, should also be used in similar replacements in other units.

Task 4: “Preparation of requirements (ToR) on developing the recommendations as regards harmonization of Ukrainian and western regulatory documents on strength aspects

This task dealt with the acceptability of the strength calculations for safety valves of the primary and secondary systems against Ukrainian regulations (such as pressurizer safety valves, steam generator safety valves and feed water control valves).

The objective of the task was to develop the Technical Requirements for a future study to compare the strength requirements specified in Ukrainian codes and standards and those used by the EU suppliers for valves; the French RCC-M code was identified as the basis.

The experts identified significant deviations between the Ukrainian and EU standards and rules in the field of strength calculations and criteria, and recommended a comparative study of these standards and rules with the aim of identifying the differences and analyzing them for the benefit of the Regulator.