The Obama administration levied fines totaling nearly a million dollars this week against two of the nation’s nuclear weapons laboratories, mostly for failing to keep track of classified materials and for repeatedly disclosing information related to nuclear weapons design in public presentations stretching over nearly a decade.

In notices published by the Energy Department on June 5, the National Nuclear Security Administration provided only general information about the materials and data that got loose but said the breaches were among the most serious such infractions, and could have an “adverse impact on national security.”

It said a private company that operates Sandia National Laboratories in Albuquerque, New Mexico, would be fined $577,500 for its poor handling of classified nuclear bomb design information.

A second private company that operates Los Alamos National Laboratories, also in New Mexico, faced a fine of $247,500 for failing to secure something that was identified only as classified “matter,” according to one of the notices, as well as a fine of $150,000 for an unrelated employee safety violation.

The notice did not explain what the missing “matter” is, but accused Los Alamos of conducting a poor investigation into what happened to it and of wrongly assuming, for years, that it had been safely destroyed. (...)