A 0.75" SwageLok ball valve that was taken out from the T1 cooling package was inspected (SS-45S12).

All valves in the T1/T2 cooling packages likely leaked due to damage to plastic/rubber sealing components. 

SEE PICTURES ATTACHED.

We can see that some bits of white plastic, possibly a bushing, has disintegrated and is leaking out from the valve shaft.

Additionally, there is a considerable amount of dirt/grit in and around the ball.

The surface of the valve opening exibits visible signs of wear (new valve opening is perfectly smooth).

Finally, a red-colored material is found on some small stainless steel parts which is either buildup from contaminants in the line or worn silicon/rubber lining.

Hypothesis: 90 um filter which had not been replaced caused the water in the line to build up particulates and wear plastic/rubber parts in the valve, causing them to leak. 

From the previous test (ELOG 315), we know that the leak is not due to depressurization.