Two nuclear safety engineers at Babcock & Wilcox Co. testified yesterday they tried unsuccessfully to warn customers of the possibility of a nuclear accident similar to the one that crippled Three Mile Island.

The engineers, Joseph J. Kelly and Bert M. Dunn, told the Kemeny Commission investigating Three Mile Island for the White House that they wrote memos to Babcock supervisors and had repeated discussions with managers over what they felt was a need to warn Babcock customers of the possibility of a loss-of-coolant accident like the one eventually suffered at Three Mile Island.

The date of Kelly's first memo was Nov. 1, 1977, while Dunn wrote his first memo Feb. 9, 1978, more than a year before Three Mile Island. Babcock customers were never notified of their concerns.

"I wrote follow-up memo and had discussions with people about the need to notify customers and I operated under the assumption that new instructions would be distributed to customers," said Dunn, who is manager of emergency core cooling system analysis for Babcock & Wilcox in Lynchburg, Va. "But to my knowledge, customers were never notified."

Kelly and Dunn told the Kemeny Commission their concerns were triggered by an accident Sept. 24, 1977, at the Davis-Bessie nuclear plant of Ohio's Toledo Edison Co., which, like Pennsylvania's Metropolitan Edison Co., had bought its nuclear plant from Babcock & Wilcox.

The Davis-Bessie accident involved a sudden loss of cooling water that shut down the nuclear reactor. The accident occurred when a pressure relief valve stuck open, venting thousands of gallons of cooling water away from the reactor, and plant operators mistakenly throttled back the pumps pouring emergency cooling water onto the reactor to make up the difference.

While the nuclear core at Davis-Bessie was never exposed the way the core at Three Mile Island was, there were striking similarities in the events that led to both accidents. The pressure relief valves at both places stuck open, releasing essential cooling water from the reactor; the pumps feeding emergency coolant to the cores were throttled back or turned off, denying replacement cooling water to the cores.

"One difference in the two accidents was that the Davis-Bessie operator quickly realized his emergency valve was stuck open and closed it after 20 minutes," Kelly testified. "The other difference was that the Davis-Bessie people throttled back two pumps; the Three Mile Island people stopped all four. To me, that's a significant difference."

The accident at Davis-Bessie prompted Kelly to write a memo to seven B&W supervisors in which he recommended that all Babcock customers be given guidance as to how to avoid a similar accident at their plants.

"Do not bypass or otherwise prevent the actuation of high or low pressure injection (emergency cooling) under any conditions except a normal, controlled plant shutdown," Kelly said the new instructions should read. "Once injection is initiated, do not stop it unless temperature is stable or decreasing and pressurizer level is increasing...."

Kelly said that 10 days after he wrote his memo he received a memo from F. J. Walters, a supervisor in the Nuclear Service Division, who said he disagreed with Kelly's concerns. Walters told Kelly he thought the operators at Davis-Bessie had acted correctly; besides, he said, the accident was "of no magnitude."

"He was confused," Kelly said of Walters. "Its (the Walters memo) only value to me was to escalate the problem to Mr. Dunn."

Kelly and Dunn said they talked over the "lack of response" among Babcock supervisors to Kelly's memo and decided to pursue the issue more vigorously. Dunn said he wrote a memo to Jim Taylor, manager of the licensing division at Babcock, urging him to address the accident at Davis-Bessie in a more constructive way.

"I believe that Toledo (Davis-Bessie) was fortunate," Dunn said in the memo. "Had this event occurred in a reactor at full is quite possible, perhaps probable, that core uncovery and possible fuel damage would have resulted."

Dunn said Taylor responded by rerouting his memo back to the Nuclear Service Division, where Kelly had run into his original obstacle. Dunn said he never heard back and assumed that customers had been notified of his concern.