HOUSTON, March 22 (Xinhua) -- Environment regulators in the U.S. state of New Mexico have withdrawn a permit for expansion of the country's only underground nuclear waste repository which was shut down by a radiation leak last month, U.S. media reported Saturday.
The New Mexico Environment Department have notified the Waste Isolation Pilot Plant (WIPP) that it has withdrawn a pending draft permit for expansion of the plant, citing recent back-to-back incidents including the radiation leak and a fire, local TV KOB reported.
The underground dump was shuttered on Feb. 14 when air sensors detected unusually high levels of radioactive particles on its underground levels.
It has been kept closed as reports came that small amount of radiation was detected both at the underground and surface levels. A total of 17 workers were confirmed positive for radiation, but the level of their exposure was "extremely low," according to the U.S. Department of Energy.
The sealed dump now sees no immediate schedule of recovery efforts. Los Alamos National Laboratory, a nuclear weapons manufacturing facility in New Mexico which used to store its refuse at the dump, was forced to relocate its radioactive waste to Texas.
The cause of the radiation leak still remains unknown. A truck fire was reported at the underground site on Feb. 5 and prompted evacuations, but officials said the fire was in a different part of the site and did not seem related to the leak.
The repository stores "transuranic waste" leftover from nuclear weapons research and testing from the nation's past defense activities, according to the Energy Department website. The waste includes clothing, tools, rags and other debris contaminated with radioactive elements, largely plutonium.