QA in radiation surveys: why <10% deviation matters

When a regulator asks "is this site safe?", the only acceptable answer is one backed by traceable data. That's where QA earns its keep. Without it, a number on a report is just an opinion expressed in decimals.

Calibration first, measurements second

Every gamma spectrometer in our fleet is calibrated against IAEA-traceable reference sources before it leaves the prep room. We track each instrument's calibration history and retire devices when their drift exceeds the budget — a discipline most operators don't see, and that quietly distinguishes a defensible report from an indefensible one.

The 10% rule

Our QA Manual mandates a deviation budget of less than 10% across calibrated devices. That number isn't arbitrary — it sits below the dose-rate variability we'd accept as 'real change' between two surveys, so any signal we see in the data is a real signal, not an artifact of instrument drift.

“You can't remediate what you can't measure precisely.”

What this means for clients

For an operator, this discipline shows up as fewer surprises in the regulator's office, faster sign-off after remediation, and a smaller envelope of doubt around every reported number. It's invisible until something goes wrong — at which point it's the only thing that matters.