PSA
PSA turns up in 2 fields: adhesives, nuclear. Here is what it means to the people in each one.
PSA in adhesives
Pressure-sensitive adhesive, the always-tacky layer on tapes and labels that bonds under finger pressure with no cure step.
Pressure-sensitive adhesives are soft viscoelastic polymers, mainly acrylics, rubbers and silicones, that flow into a surface under finger pressure and resist separating. They need no heat, solvent or reaction at the point of use, which makes them the basis of tapes, labels, protective films and medical dressings. They trade some strength, heat and creep resistance for that convenience.
"Switch the nameplate from screws to PSA, but spec an acrylic, the rubber one will creep in the heat."
PSA in nuclear
Probabilistic safety assessment: a systematic model of how accidents could happen and how likely each outcome is.
Probabilistic safety assessment builds event trees and fault trees covering initiating events, equipment failures and human actions to estimate the frequency of core damage (Level 1), of radioactive releases (Level 2) and of off-site consequences (Level 3). It identifies the dominant contributors to risk and supports decisions on maintenance scheduling, design changes and inspection priorities. US practice calls it probabilistic risk assessment.
"PSA says taking that pump out with the diesel already down puts us in orange, reschedule it."