What could be a consequence of a steam turbine operating at critical speed without regulation?

Operating a steam turbine at critical speed without proper regulation can lead to significant mechanical failure. Critical speed refers to the rotational speed at which the forces acting on the turbine create vibrations that can resonate with the natural frequencies of the turbine structure. When this happens, excessive vibrations can impose stress that exceeds the material limits of turbine components. This can result in issues such as blade deformation, bearing wear, or even catastrophic failures like fractures or disintegration of parts.

In contrast to the other options, which imply positive outcomes or stability, the consequence of uncontrolled operation at critical speed emphasizes mechanical integrity and reliability. Therefore, the focus on potential mechanical failure encapsulates the risks inherent in such operating conditions.