Muskrat Falls generating unit must be fully dismantled, says report

At least one of the generating units at the Muskrat Falls hydroelectric dam must be fully dismantled to undergo repairs — a "significant undertaking" for which the cost and timeline are unknown, according to a report submitted to the Public Utilities Board in June.

The latest independent monitoring report from Liberty Consulting says repeated "vibration issues" affecting Unit 2 have been reported since 2021, and that annual maintenance earlier this year showed parts of the unit were damaged "due to suspected hydrogen embrittlement," which can lead to cracks in metal under stress.

"Hydro has stated that it cannot identify how hydrogen got introduced in the metal, but noted that it could have come during [the] manufacturing process, site storage, assembly, or operation," the document reads. "The resulting uncertainty has implications for the existence of the phenomenon at the other three generating units, which Hydro considers possible."

Could all 4 generating units be affected?

Until the problem with Unit 2 is identified, "it remains prudent to consider the potential for material challenges to the short-term operation and long-term accelerated degradation of all the Muskrat Falls units," notes the 13-page report, which adds that "planning and scheduling for the permanent solution remain pending."

Newfoundland and Labrador Hydro president and CEO Jennifer Williams said Wednesday that "it's not impossible" that all four units could be affected by hydrogen embrittlement issues, but added, "We're going to do inspections on the other units and we're not seeing any of the characteristics in the other units that would suggest it also exists in units 1,3 and 4."

Williams said a full plan on Unit 2 repairs will be fleshed out "in the next year or two."

Hydro spokesperson Jill Pitcher wrote in a statement Wednesday that the "majority of the costs will be covered through the contractor's construction insurance."

"While there may be some costs to Hydro, these will be determined when the plan and timeline are finalized," added Pitcher, who also said there is currently "no impact on Hydro's ability to supply its customers in the province or outside the province" and that Hydro would "ensure there are no supply issues" once repairs begin.

Three of four units report problems

According to the report, the only Muskrat Falls generating unit not to report problems in the first quarter of the year was Unit 4.

Liberty says Unit 1 was temporarily shut down due to a cracked discharge ring flange, noting "an earlier crack had occurred in the same area."

A temporary fix by manufacturer Andritz allowed the turbine to return to service for 125 hours at a reduced power level of 140 megawatts. The generating units are designed to operate at 206 megawatts. Liberty's report says Hydro was expected to complete permanent repairs "imminently," although similar fixes are also anticipated for Unit 3.

A separate issue caused Unit 3 to trip during routine operations, according to Liberty. Hydro subsequently discovered and repaired damaged cables and resistors in the unit, but has no idea how the damage occurred because monitoring software wasn't functioning.

"The incident led to the discovery that equipment presumably in continuous use to record and trend data had not been operating, thus precluding determination of underlying causes of the damage observed," writes Liberty.

Intractable issues, costly fixes

The Liberty report also highlights several other previously reported issues with the Labrador-Island Link transmission system, including faulty turnbuckles — metal parts used to regulate the length or tension of cables — in southern Labrador and on Newfoundland's Northern Peninsula. 

When the turnbuckles fail, a problem called "galloping" has occurred, as high winds push on iced-over power lines and cause a jumping motion that affects transmission.

Faulty turnbuckles appear to have caused a trip on the link in a remote section of the Northern Peninsula last December. Repairs took weeks because the lines were only accessible to heavy equipment after tens of kilometres of access roads had been cleared. 

"Corrective actions now under internal evaluation consist of selective installation of galloping mitigation devices (at a cost in the range of $100,000 per span affected) or alternate turnbuckle hardware," notes the report. 

In total, about 3,200 transmission towers make up the Labrador-Island Link, but the report does not say how many spans would need to be upgraded. Hydro expects a full report on the turnbuckles and recommended solutions is expected in September, according to Liberty. 

Williams said Thursday she expects work on the LIL to extend over four years.

The Liberty analysis also notes that all three synchronous condensers at the Soldier's Pond switchyard outside St. John's — machines that help maintain system stability and keep voltages at specified levels — are in operation but continue to face problems related to vibration and bearing tilt.

"A complete bearing redesign remains the long term corrective action to resolve the bearing tilt issue," according to the report. "Hydro has reported an expectation that the complete redesign effort will take about 12 months to complete, but no firm schedule yet exists for redesign and subsequent repair."

Final cost of project pegged at $13.5B

On June 29, after she presented the Crown corporation's annual report, Williams said the cost of constructing Muskrat Falls had jumped $133 million, reaching $13.5 billion. The government sanctioned the project in 2012, when the full cost, including financing, was believed to be $7.4 billion.

Williams, however, promised that $13.5 billion would be the beleaguered project's final price tag.

"No more updates," she said. "No more surprises."

Pitcher, the Hydro spokesperson, wrote in an email, "These are new assets that will provide value for decades, with many similar plants having units in service for up to 100 years.

"This early operational period is the time to identify and resolve any issues, as can be the case with new assets."

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