... [T]he P5+1 negotiators ... have reportedly been focusing on the removal and monitored storage of key centrifuge equipment in such a way that re-installation would be difficult and time-consuming.  However, accomplishing build-back time frames of six to twelve months can be difficult to achieve in practice. ...

Some analysts, including those at ISIS, have discussed imposing essentially what have been called in the North Korean context "disablement" steps, which would not involve the destruction of any equipment but delay the restart of installed centrifuges.  However, ISIS's attempts to define disablement steps on the centrifuge plants appear to be reversible in less than six months of diligent work.  This time period applies to proposals to remove the centrifuge pipework from the centrifuge plants. ...