Waterford — An independent state consumer protection agency and a nationwide power company recently filed challenges to regulators who agreed to keep financial data on Millstone Power Station under wraps.

Millstone owner Dominion Energy recently turned over two confidential exhibits to the Department of Energy and Environmental Protection and the Public Utilities Regulatory Authority. The agencies are examining Millstone's finances along with potential energy market changes that Dominion and local officials say could prevent premature closure of the facility.

Dominion claims the data it turned over demonstrates Millstone, like other struggling U.S. nuclear plants, suffers from high operations costs and competition with cheaper natural gas. Regulators, whose report released Thursday said Millstone would be profitable through 2035, granted Dominion's request to keep the financial data secret.

But the Office of Consumer Counsel, which advocates for Connecticut's utility customers, said in a recent motion that it has "the absolute right" to access substantive PURA documents to see how the data could eventually impact consumers across the state.

Consumer Counsel Elin Swanson Katz said in an interview that the agency would keep the data confidential as requested by Dominion, which says the information amounts to trade secrets competitors want to get their hands on.

"We'd like to see the information so we have a better sense of the details," Katz said. "We've been involved in parts of the process, but I think to really feel comfortable that we understand the final report (on Feb. 1, 2018), we'd like to see the data."

Another motion filed last week came from energy company NRG, one of several firms and groups questioning the need for proposed energy market changes they say would unfairly tip the scales in Dominion's favor.

NRG's motion said it doesn't object to "protective treatment for Millstone's plant-specific financial data." But it called a protective order on the data "overly broad in its reach," saying it "limits the public's understanding of the information Dominion has provided."

NRG called on Dominion to identify the title and nature of the secret documents; to submit redacted versions to the public; and to submit "a sworn affidavit testifying to the veracity of the financial data submitted and identifying what, if any, independent auditing supports the data provided."

Millstone spokesman Ken Holt said Dominion was reviewing OCC's and NRG's motions. Holt has described NRG as a competitor looking to gain an edge.

PURA officials could not be reached for comment, but DEEP spokesman Chris Collibee said the agencies were still studying the separate motions.

"We are accepting comments and responses to the motions from OCC and NRG until Dec. 21, after which time we will take all positions into consideration and we will issue a ruling after that," Collibee said. "As this matter remains under review, it would be inappropriate to comment at this time."

Comments on OCC's and NRG's motions can be submitted on DEEP's website or emailed to DEEP.EnergyBureau@ct.gov.

DEEP and PURA are conducting their Millstone analysis after a July executive order from Gov. Dannel Malloy. Malloy signed a bill in October that could eventually allow Millstone to compete with renewable and low-emitting sources by selling its electricity in a state-sponsored bidding process.

The agencies are set to release a final report on the matter Feb. 1, 2018.

Energy companies like NRG, Calpine and Dynegy have fought against proposed market changes, describing them as subsidies for nuclear power.

NRG spokesman Dave Gaier called potential energy market changes "a cynical scheme," especially given regulators' and consultants' recent reports projecting Millstone will remain profitable for several years.

Holt noted Dominion has consistently sought market changes but not "straight subsidy" programs that other states have implemented to help keep nuclear plants operational.

"All we've asked for is an opportunity to sell our power to the state," Holt said in a recent interview. "If the price is good, they buy it. If they don't like the price, they don't buy it."