PLYMOUTH — Operators at Pilgrim Nuclear Power Station have been allowed to retract a notification sent late last month to federal regulators when some improperly installed clamps were discovered in the hydraulic control rod piping system that potentially could have prevented the system — used to shut down the reactor quickly in an emergency — from fully functioning in an earthquake.

Subsequent study by plant engineers determined the piping would have functioned despite the incorrectly installed support clamps. Patrick O’Brien, spokesman for Pilgrim's owner-operator Entergy Corp., said the support clamp configuration had not matched the engineering design.

“The affected pipe supports have been restored or reworked to the proper design condition in accordance with the drawings,” O’Brien wrote in an email.

Neil Sheehan, spokesman for the Nuclear Regulatory Commission, said the retraction frees Entergy from further study of the issue and “allows them to focus on other things.”

The Plymouth reactor has been shut down since March 6, when operators discovered a leak in a system needed to heat water before it is pumped into the reactor.

While operators addressed that problem, the March 13 storm extensively damaged the reactor's start-up transformer, which had to be replaced. The new start-up transformer has been installed, and other systems are being checked and tested before the reactor restarts, Sheehan said.