Xcel finds reason for shutdown of Monticello nuclear plant

Nov 22 - McClatchy-Tribune Regional News - Leslie Brooks Suzukamo Pioneer Press, St. Paul, Minn.

The Nuclear Regulatory Commission said Monday that its on-site inspectors at the Monticello Nuclear Generating Plant are monitoring an emergency shutdown of the plant over the weekend.

The 600-megawatt plant shut down automatically at 11:12 p.m. Saturday when safety systems detected low oil pressure in its turbines, according to Xcel Energy, which owns and operates the plant.

There was no radiation release and no danger to the public or plant workers, Xcel Energy spokeswoman Mary Sandok said.

Xcel officials said the outage is not expected to be lengthy but declined to specify how long. The utility will buy power from other utilities or off the grid to make up for the lost electricity.

The single-reactor plant, located about 40 miles northwest of Minneapolis, generates enough electricity to power nearly 500,000 homes.

The NRC's resident inspectors at the plant are monitoring the emergency shutdown, also known as a "scram," to identify the cause, NRC spokeswoman Viktoria Mitlyng said.

The NRC also is trying to locate a part missing from a device used to monitor the level of nuclear reaction inside the reactor, Mitlyng said.

The monitor, which is highly radioactive, was taken out of service for replacement. It typically is stored in the spent fuel reactor pool for safekeeping until it can be shipped to a disposal site, Mitlyng said.

There is no indication that the missing part is outside of the pool -- it simply could not be found in its designated

location, so workers will search the entire pool, Mitlyng said.

This is the third non-scheduled outage reported at the nuclear power plant this year.

"While we are still investigating the cause of the weekend outage, the causes of the first two were unrelated," Sandok said.

On Oct. 21, the plant had a 10-day outage when a cable failure caused a transformer to lock out, interrupting nonsafety-related electricity from reaching the plant from the grid.

In June, Xcel shut down the plant to replace a faulty safety valve that had been installed on the plant's main steam line just a few months previously during a scheduled refueling outage.

Leslie Brooks Suzukamo can be reached at 651-228-5475. Follow him at twitter.com/suzukamo.