Okay... "pressure seal valves"... you mean a check valve? Doesn't seem likely you mean a check valve as they would only seal against unwanted revesre flow.

I realize we are all laymen here but I am am having a hard time following the logic at times. If youse are having a hard time following my logic, please cite me and edify me or at least question me. Sometimes, I think off the top of my head... I throw ideas out for the hell of it.

Perhaps it's useless and only serves for banter while we await what we all hope will be resolution of a very serious situation which may get to "criticality" (the word they have been using on NHK). The key point is... it is not critical yet. The sky has NOT fallen and is NOT falling... it's lookin like storm clouds movin in but the wind hasn't picked up enough to blow all hopes away.