Slovakia’s Mohovce 3 commissioning slowed by insufficient documentation

3 September 2020

Testing underway at Mochovce 3 (Photo credit: Slovenské elektrárne)Slovakia’s Nuclear Regulatory Authority (ÚJD) said on 2 September that inspections had identified no problems which would prevent commissioning of unit 3 at the Mohovce nuclear power plant. It noted on its website: “The state of readiness of unit 3 of the Mohovce 3&4 nuclear facility for the issuance of a UJD permit for commissioning is monitored and regularly evaluated.”

During the summer months, work was carried out to eliminate previously deficiencies, identified during local inspections of buildings carried out by the building authority and the reheating of the primary circuit carried out at the beginning of 2020. “No new major deficiencies preventing the continued commissioning were identified,” UJD said.

However recent inspections had found “insufficient documentation of compliance with quality requirements, ie the permit holder has yet to complete, supplement or specify documentation proving the quality of certain equipment and work performed”.

Deficiencies identified during hydro testing have been eliminated and device and system parameter settings have been optimised. The verification of electromagnetic compatibility is being completed, and the cables are being modified before their final covering. The last modifications are being made to the buildings, “which must be completed for their possible premature use”.

Design documentation has been checked, official tests and certification of the equipment for the conventional part of the plant is completed. The documentation proving the readiness of the unit for fuel loading has been specified and updated.

According to UJD, the quality and properties of the materials of the pipe parts have been verified according to the approved methodology. All components classified in terms of their impact on nuclear safety in the highest safety categories have been inspected. Producers of metallurgical semi-finished products as well as authorised legal entities were contacted to verify the authenticity of the inspection certificates. Evaluation of the results and a conformity assessment by material specialists is in progress. “Based on the results of the evaluation, it may be necessary to extend the originally specified scope of verification for components classified in lower safety classes,” UJD noted.

UJD noted the need to prove the readiness of the reactor unit for the introduction of the first fuel cartridge and the start of active tests “comprehensively in all assessed areas”, from completion of buildings, through completion of assembly activities, successful completion of inactive system and integral tests, elimination of detected defects and shortcomings , environmental protection, and the readiness of personnel and operational documentation.

In addition to completing the verification of the quality and properties of the metallurgical materials used on selected equipment, “it remains to demonstrate the required resistance of the systems to electromagnetic interference, complete the certification of engine room equipment and meet the conditions of other supervisory authorities”. UJD said that, unless the permit holder proves compliance with all legislative requirements, it will not issue a permit for the commissioning of Mochovce 3.

UJD Director Miriam Vachová told SITA that “the permit holder has yet to complete, supplement or process documentation proving the quality of certain equipment and work performed”. She declined  to comment on the potential dates of putting unit 3 into operation.

According to Economy Minister Richard Sulík Mochovce 3 could be in operation at the end of this year, or at the latest at the beginning of 2021. Mochovce 3 was 99.7% complete at the end of May and Mochovce 4 was 87.3% complete. The original dates for  were 2012, and 2013 butthe deadlines have been postponed several times. Costs have also increased with completion now expected to cost €5.7 billion. The original estimate was  €3bn.

Construction of the Mohovce nuclear plant began in 1982, and the first two units were commissioned in 1998 and 1999. Construction of the second phase of the plant (Mochovce 3 and 4) started in 1986, but was frozen in 1992 in the wake of the Soviet collapse. Work resumed in 2009 but was suspended again after the 2011 Fukushima accident for upgrading to comply with new safety requirements.

Testing underway at Mochovce 3 last year (Photo: Slovenské elektrárne)

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