The Justice Department has acknowledged that there has been widespread discrimination against women working in professional positions at the Department of Energy, and has set up a procedure that could award those woman as much as $12 million in damages.

The agreement, which must be approved by a federal judge, would end a suit brought by a manpower analyst" for herself and some 255 other womanwho work for the agency as scientists and in other professional positions.

Government attorneys said they decided to settle the case - which probably will result in the highest damage payment in a discrimination case involving a single government agency - after statistics clearly showed a pattern of hiring and promotion that reflected sex bias of supervisors.

According to some of those records, since January 1975 women at the agency were hired at salaries that were on the average about $3,000 less than equally qualified male counter-parts, and that women had to wait far longer than men for promotions.

The suit also reportedly alleged that male supervisors had made sexual advances toward women employes and that highly qualified women scientists, were assigned to menial office tasks. However, virtually all the incidents were filed in sealed court documents.

"They just didn't like women over there," said one attorney familiar with the case. He said there was "just no defense" that the government could raise to the statiscal record.

The government's own experts reportedly agreed there was an $8 million discrepancy between the salaries for men and women doing the same kind of work.

That general disparity was reflected in a range of 15 subcategories as well, according to papers filed in the case, involving women employed as geologists, lawyers and personnel specialists.

Attorneys said the problem at Department of Energy and its predecessor agencies, the Atomic Energy Resources Development Administration, apparently 'arose out of their history of being heavily staffed ex-military personnel who did not become properly sensitive to women working there.

"It amounted to a buddy system, and the agency was known as a good agency to transfer to in order to get a promotion if you knew the right people," one attorney said.

The consent agreement filed in U.S. District Court here was approved at the highest levels of the Justice Department, and signed by U.S. Attorney Earl J. Silbert, Assistant U.S. Attorneys Robert N. Ford and Stephen S. Cowen, Department of Energy attorney Henry A. Gill Jr. and Gary Howard Simpson, who represented the plaintiffs.

It reflects the acknowledgement on the Justice Department's part tha a clear case of discrimination existed, but does not discuss the amount of possible damages at all.

The exact amount will be determined by a court-appointed master to whom the individual women must file their claims, according to the agreement.

The damages could include back pay for each woman, and in certain instances could include what is known as "frontpay" - paying a woman at a particular level even though no job is open at that level.

Attorneys in the case said that a total of $12 million could be awarded to the women. Even the lowest government estimate of the possible awards was given by a government attorney as "millions" of dollars.

The suit was originally brought in early 1976 by June Chewning, who came to attorney Simpson with the complaint that she could not get a fulltime job at ERDA.

At the time, according to court records, she was working 39 1/2 hours a week for the agency plus occasional overtime as a part time employe, and was a recognized expert in analyzing work patterns at nuclear plants. However, she said, she was told there was no fulltime position for her.

In addition, she said in court papers that she had poor promotion and transfer opportunities and was forced to do clerical work that could have been done by lower-ranking males in the office.

In addition to the 225 women who have been identified as members of the class of professionals affected by consent agreement, another 100 women declined the opportunity to take part in the suit, according to court records.

Lawyers in the case said it is unclear at this point whether those women who do not participate in the suit will get monetary damages for alleged discrimination against them.

Also filed with the consent agreement yesterday was a copy of the Department of Energy's new equal employment opportunity affirmative action plan dated June 19.

It said a recent review of the agency showed that minorities and women were "drastically underrepresented in upper-level professional positions" and that the department ranked eight among 12 cabinet-level agencies in overall use of women.