(WBIR – OAK RIDGE) During a two-month period five individuals experienced throat irritation and were coughing due to possible air quality irritants upon entering Building 9731 at the Y-12 National Security Complex.

Research activities in Building 9731 were suspended for a month after the second event.

Public Affairs Manager Steven Wyatt with the National Nuclear Security Administration said Y-12 Industrial Hygiene has taken extensive air samples in the building to detect any unknown irritants in the building.

On Feb. 27 the Defense Nuclear Facilities Safety Board issued a report from a Feb. 12 investigation when the plant shift superintendent dispatched fire department personnel and a hazardous materials team to Building 9731.

The report states, "Building 9731 is a legacy facility and not normally occupied, but a technician from the development organization was conducting a researched-related work activity in the facility that required the evaporation of lithium hydroxide solution."

Since 1974, the building has been used as a "development facility" for testing of small-scale processes, two of which are going on now.

It was used in World War II to help produce Uranium-235 for the atomic bomb dropped on Hiroshima, Japan, that helped end the war against Japan.

It continues to house the shell remains of the original Alpha and Beta prototype calutrons used in the research and uranium production process.

Tours have been conducted in the building because of its historic significance. However, no tours were led through the building during the operation of the equipment, and no visitors were exposed to the air quality irritants.

Wyatt said at this time tours have been suspended.