Test results have come back clean for two workers being checked for radioactive exposure at Hanford's 242-A Evaporator this summer.

Some 29 workers at the evaporator were sent for whole body counts after a seal on a pipe from a waste storage tank failed. It created an open ventilation path from a tank holding high level radioactive waste to the evaporator's condenser room.

Tests for 27 of the workers showed no exposure, but the whole body counter detected cesium 137 at levels slightly above established detection levels. The levels were too low to calculate a radiation dose to the workers' bodies.

As a precaution, urinalyses were done for those two workers. The completed tests showed no radioactivity in their bodies above background levels.

Washington River Protection Solutions considers the two whole body counts with readings to be false positives. The Department of Energy contractor continues to investigate why the ventilation pipe seal failed.