  We calculate the lifetime of the deuteron from dimension-six quark operators
that violate baryon number by one unit. We construct an effective field theory
for $|\Delta B|=1$ interactions that give rise to nucleon and $\Delta B=1$
deuteron decay in a systematic expansion. We show that up to and including
next-to-leading order the deuteron decay rate is given by the sum of the decay
rates of the free proton and neutron. The first nuclear correction is expected
to contribute at the few-percent level and comes with an undetermined
low-energy constant. We discuss its relation to earlier potential-model
calculations.
