Workers found contaminants in higher quantities as they moved into part of a Western nuclear-waste site vacated in February, the Associated Press reports.
Crews would need to re-enter the subterranean corridors of New Mexico's Waste Isolation Pilot Plant a fifth time to isolate the source of airborne radioactive materials detected there, according to Thursday remarks by Tammy Reynolds, deputy recovery chief for the U.S. Energy Department. Underground portions of the site have been off-limits to personnel following a contamination incident, which came days after a vehicle caught fire inside the facility.
Reynolds said U.S. personnel hope to obtain further details next week. Crew members had to end their most recent venture into the site after five hours on Wednesday, as temperatures rose inside their protective clothing and power for their breathing apparatus dwindled, AP reported.
The Energy Department official said the entry team investigated both of the facility's waste rooms that had not previously been permanently closed off. Waste is entombed in five additional storage "panels," but workers rendered the airtight chambers permanently inaccessible after they reached capacity.
"It doesn't seem to us that the contamination came from Panel 6, that the source came from Panel 7," Reynolds said. Panel 6 had been completely filled but not closed off, making the latter chamber the only area receiving waste at the time of the incident.
Personnel might receive help from robotic equipment as they attempt to determine the source of the escaped contaminants, according to AP. Suspected culprits include a waste barrel possibly punctured by moving equipment, or by or a ceiling that may have fallen.