WASHINGTON (CNN) -- The nation's three nuclear weapons laboratories have had almost 60 serious accidents or near misses in the past seven years, according to a report released Wednesday by the Government Accountability Office.
An explosion at Los Alamos in 2002 sent debris into the air with enough force to knock out a piece of wall.
It blames "a relatively lax attitude toward safety procedures" which has created "an environment where workers can become complacent about following safety requirements, and managers about enforcing them, raising the potential for accidents."
The GAO reviewed almost 100 reports from Los Alamos in New Mexico, Lawrence Livermore in California and Sandia which has campuses in both California and New Mexico. All are nuclear weapons laboratories that handle extremely dangerous materials like plutonium.
These three facilities are overseen by the National Nuclear Security Administration.
The report cited "weaknesses in identifying safety problems and taking appropriate corrective actions," and a lack of oversight by the NNSA for many of the problems.
"The NNSA weapons laboratories, which conduct important but potentially dangerous research, have experienced persistent safety problems despite years of effort to make the laboratories safer," the GAO report concluded.
Some of the accidents have caused "serious harm to workers or damage to facilities," the report said.
These included worker exposure to radiation, inhalation of toxic vapors and electrical shocks. While the accidents resulted in no deaths, they did contribute to the temporary shutdown of facilities at Los Alamos in 2004 and Lawrence Livermore in 2005.
One accident of concern took place at Los Alamos National Laboratory in New Mexico in 2000, when seven workers were exposed to "significant doses of radiation" when a piece of equipment failed.
Four of the seven required immediate medical help, according to the report. Poor worker communication and training contributed to the accident, which took place because the laboratory did not take corrective action after other similar accidents, the report said.
That mishap "ranked among the top 10 worst radiological intake accidents in 41 years of data gathering by the DOE (Department of Energy) and its predecessor agencies," according to the report.
Also at Los Alamos in 2002, liquid chlorine dioxide unexpectedly formed and exploded during an experiment, sending debris into the air with enough force to knock out piece of wall and ceiling.
Two researchers working on the experiment escaped death or serious injury when one of them noticed temperatures rising in the equipment, and both fled the room. The accident was caused by not implementing existing safety requirements, the report said.
In another incident, a package containing radioactive material was shipped from one part of Los Alamos to another, but no warnings were visible on the package.
A worker opened it, exposing himself and ultimately others -- both at work and at home -- because the contamination was not discovered for 11 days. Additionally, some non-radioactive parts the worker touched and contaminated were shipped to Pennsylvania.
The GAO noted that NNSA has taken some steps to improve the safety situation at the laboratories, but "ineffective implementation" of safety guidelines has continued to contribute to accidents.
"Given the persistent nature of safety problems at the laboratories, it appears that either the identification of the underlying causes or the corrective actions taken have been inadequate," the report said.
The GAO made several recommendations for improvement, including an annual report to Congress "on progress toward making the weapons laboratories safer, including the status and effectiveness of safety improvement initiatives, using outcome-based performance measures."
The NNSA said it "generally agrees" with the GAO's findings, but believes its safety record has been "favorably impressive" and its oversight of safety procedures "excellent."
One of the congressmen who requested the report said he expects conditions at the labs will improve.
"Now that the National Nuclear Security Administration realizes the persistent safety problems associated with our national weapons laboratories, it is my hope that these problems will be corrected in a timely manner, and that employees at the laboratories will have a safer environment to work in," said Rep. Ed Whitfield, R-Kentucky. E-mail to a friend