Continuing conflicts over nuclear power sliced 16 percent off the first quarter profits of Public Service Co. of New Hampshire, builder of the embattled Seabrook nuclear power plant.

The firm lost 18 cents a share in earnings from the first quarter last year, from $1.12 to 94 cents, company President William Tallman told a stockholders meeting today.

Earnings for the 12-months period ending in March were $3.13, down from the 1978 level of $3.25, he said, attributing the downturn to inflation and recent sales of stock - which boosted outstanding shares 34 percent to 11.3 million shares -needed to pay for construction costs at Seabrook.

Nuclear opponents, using their position as shareholders, interrupted traditional profit-and-loss descussions several times to engage management in impromptu debates.

"We need far less emotion and far more reason and judgment," said Tallman, who was supported by one stockholder asserting: "I'm for nuclear power; I'm sure you gentlemen will use the moral values needed to protect us."

Unconvinced was Arnold Alpert, who cited the accident at Three Mile Island and evidence of increased cancer among residents living near a nuclear facility in Rocky Flatts, Colo. "I think these are emotional and moral concerns," he said.

But Tallman countered, "There is no such thing as risk-free energy; it is necessary to wight the risks and costs and find a proper balance."

"Seabrook needs to be built and it will be built," said Tallman, who has been quoted saying, "in hind sight, knowing what we know now . . . there is some question whether we would have embarked on Seabrook."

There is still a need for substantial financing in 1979, Tallman said, despite the company's reluctant agreement to sell 22 percent of its 50 percent stake in the atomic plant.

A major stock sale was postponed last November when the utility's biggest ally, Gov. Meldrim Thomson, lost election to Hugh Gallen, who campaigned mostly against the so-called Construction Work In Progress (CWIP) 9 percent surcharge with $9 million in cash.

Gov. Gallen on Monday signed a measure outlawing CWIP, undaunted by the company's warnings that New Hampshire's residents ultimately would wind up paying more for electricity because the firm would have to buy back power from other utilities to meet demand.

The company responded today by saying it would seek a rate increase. Tallman declined to reveal how much it would ask for, but Wall Street sources predicted several months ago the utility would replace CWIP with a massive rate increase.

Tallman said he would continue the fight for CWIP at a June 5 hearing of the Public Utilities Commission. The company was ordered Tuesday to file a new retail rate eliminating the CWIP charge or appear at the hearing to show the state commission why CWIP is necessary.

"We need dollars; it's a cash flow problem we're faced with," Tallman said at a news conference after the annual meeting. "If we don't get to keep CWIP or get a rate increase, we've got real problems."

A sale of one million shares of preferred to raise $25 million is scheduled next week. Another sale is scheduled for the summer, and the company plans to raise an additional $40 million to $5o million in a proposed bond sale.

The company's problems began shortly after it applied for a construction permit in 1972 to build the 2,300 megawatt twin-reactor unit. Seven years of battles with the environmentalists have resulted in costly delays, with construction halted three times by legal and regulatory challenges.

Today, Tallman said, "The major regulatory and environmental hurdles are over." But the antinuclear CLAM-SHELL alliance - which spawned similar groups nationwide and organized the 1977 demonstration in which 1,114 protesters were arrested on the construction site - is meeting this weekend to plan another massive demonstration around the end of July. CAPTION: Picture, TAKEN FROM MEETING - Public Service Co. of New Hampshire stockholder Sam Kerson, asking question at annual meeting from which he later ejected. AP