UPDATE 2-PSEG shuts N.J. Salem 2 reactor

(Updates with company, NRC comment)

NEW YORK, May 13 (Reuters) - Public Service Enterprise Group Inc (PEG.N: Quote, Profile, Research, Stock Buzz) shut the 1,130-megawatt Unit 2 at the Salem nuclear power station in New Jersey from 80 percent on May 12 due to an instrument problem related to the steam generator flow channels, a spokesman for the company said Tuesday.

He could not say when the unit would restart noting workers were still investigating the cause of the problem.

Electricity traders guessed it would return within a week.

At the time of the May 12 shutdown, the unit was increase power following a May 9 outage.

Operators manually shut the unit on May 9 from 47 percent due to high steam generator level.

At the time of the May 9 shutdown, the unit was increasing power after exiting a refueling outage earlier in the week.

It shut for refueling by March 12.

During the refuel, workers replaced the unit's four steam generators in addition to the usual refueling activities.