RICHLAND, Wash. — The U.S. Department of Energy plans to issue a $385,000 fine to Bechtel National, the contractor building a nuclear waste treatment plant at the Hanford nuclear reservation.

In a letter to Bechtel National on Wednesday, Martha Thompson, acting director of the enforcement arm of the Energy Department’s Office of Health Safety and Security, said the company had numerous opportunities to correct problems with design and construction of the plant.

The largest portion of the fine, $220,000, will be for failing to improve quality. The rest will cover problems related to piping used in “black cells,” or areas that will be so radioactively hot that workers cannot enter them during the 40 years the plant may operate.

In a memo to employees, Bechtel National, part of San Francisco-based Bechtel Corp., said it takes safety and quality seriously and has made significant improvements.

The federal government created Hanford in the 1940s as part of the top-secret Manhattan Project to build the atomic bomb. Today, it is the nation’s most-contaminated nuclear site, with cleanup costs expected to top $60 billion.

Central to the cleanup is the removal of 53 million gallons of toxic and radioactive waste from 177 underground tanks, some of which are known to have leaked, threatening the nearby Columbia River.

The waste treatment plant is being built to convert much of that waste into glasslike logs for long-term disposal underground.

Because piping in those areas will not be accessible, Bechtel is required to adhere to strict standards that include examining pipe welds by X-ray or ultrasound and documenting the materials used.

Bechtel failed to meet that requirement on about 2,000 sections of pipe from 2002 to 2005. After the problem was discovered, Bechtel took action to correct the deficiency on specific pipe orders.

But it failed to identify and do the correct work on all of the affected piping, Bechtel workers were told in the memo. The problem was discovered in 2007 by a Bechtel engineer.

As a result, Bechtel suspended work on all black cell and hard-to-reach piping in 2007. None had been installed.

The Energy Department has taken steps to improve its technical oversight of the so-called vitrification plant. In the past year, the agency has increased staff from about 95 to 147 with many of the new positions created to monitor the plant.