your valued Deep Cheque Document (DCD) is safe, as long as you look after it.
printed on archive quality paper, it will survive exposure to sunlight and other forms of radiation but it is not waterproof!
for your re-assurance - you can get replacement if it gets damaged - return your DCU to get a near-identical one - during the lifetime of the Issuer, at a nominal cost (less than 40 USD or EUR).
but if it gets stolen or lost then i can not help you...
hmm... wait a minute... except...
to fool the robbers you can frame a DCC and keep that as a decoy! - see Question #11.