Mochovce Unit 3 Completes Hot Hydro Testing

[UPDATED] Slovakian utility Slovenske Elektrame said that unit 3 of the Mochovce nuclear plant had completed all of the hot hydro testing and had moved to the next commissioning phase with the final major inspection of the unit.

Machovce NPPThe company will next carry out inspections of all major systems and equipment in the plant as a prerequisite for initiating “the physical and energy start-up.”

Post hot hydro testing, the company put Unit through though integrated tests to evaluate the “strength and tightness” of Unit 3’s hermetic zone, another word for “containment.”

The containment zone was pressurized to 150 kilopascals and the strength of the walls and ceilings and resistance to leaks were tested. The containment system consists of reinforced concrete structure of the primary circuit building. The walls are 1.5 meters thick.

“The hermetic zone tightness results achieved are two times better than the limits set by the nuclear regulatory authority of the Slovak Republic,” said Head of Commissioning Juraj Krasnansky.

The hot hydro testings' five stages included the pressure and tightness tests on the primary circuit and reactor at “nominal operating parameters” at a temperature of 265 degrees Celsius using pressure from 0.5 to 19.12 megapascals – 1.5 times the pressure reached in an operating unit.

The company also conducted functional tests of the primary and secondary circuit equipment, tests of safety systems, as well as ventilation, electrical components, control and management systems and several others.

Unit 3 “did all the defined tests and passed successfully,” the company said.

The company, however, has revised its schedule for the plant due to testing taking longer than expected. Prior to authorization by the Nuclear Regulatory Authority, the Public Health Authority, the Labor Inspectorate and the Firefighting and Rescue Corps, the company has to issue opinions “which is a time-demanding process.”

Delays will impact cost for the completion of Unit 3 and 4 by an estimated $303 million, a 5 percent increase in total costs.

“The exact dates of commissioning will depend on the licensing process, the proceeding of which will be significantly affected by the anticipated obstructions of involved parties, in particular Austrian anti-nuclear organizations,” the company said.

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