The two instrument poles located at geometrically opposite ends of the tank are indicating uniform vapor space temperature and concentration profiles. This implies that the tank headspace is well-mixed. However, during these tests the lowest sample point was 21 inches above the surface. In future tests, the instrument poles will be lowered to within five inches in order to determine if a benzene rich layer is formed near the surface. The benzene release rates are greater than expected during non-wash operations, but WSRC stated that they are still operating within their safety envelope.
Additional testing is required to determine the mechanism and ensure that controls are adequate.
WSRC is adjusting the barrel experimental program as additional information is obtained from the in-tank testing. The code is still not predicting the dynamic response of purge flow.