HVL of water for Ir-192 ?

["Dahlskog, Leif" <Leif.Dahlskog@health.wa.gov.au>]

I have been told the half value layer of normal tap water for Ir-192 is
approx. 15 cm (6 inches).

As this may have been a guesstimate, can someone confirm the value or
provide a correct value with  a reference.

regards

Leif Dahlskog
Scientific Officer
Radiation Health Section
Health Department of Western Australia