Instrumentation Problems at the Monticello Nuclear Generating Plant

The Monticello Nuclear Generating Plant is a 545 Mwe Unit powered by a General Electric boiling water reactor. Monticello achieved initial criticality on December 10, 1971 and began commercial operation on July 4, 1971 at the completion of a turnkey contract with the General Electric Company. Bechtel Corporation was the prime contractor. This paper reports on some of the unusual instrumentation problems encountered during the startup of the Monticello Plant. These problems are as follows: 1. Moisture Separator Drain Tank Level Control Problems. 2. Protection System Relay Failures. 3. Setpoint Drift of Protection System Vacuum Switches. 4. False High Pressu re Coolant Injection System Steam Flow Signals. 5. Instrument Manifold Valve Problems. Hopefully, these problems are of a general enough nature so that the Monticello experiences can benefit a majority of the readers.