Event Notification Report for August 29, 2017

PART 21 REPORT - RELAY FAILURE NUTHERM MODEL 700DC

The following excerpted report was received via fax:

"On the basis of our evaluation, it is determined that Nutherm lnternational, Inc. does not have sufficient information to determine if the subject condition would, or has, created a Substantial Safety Hazard or would have created a Technical Specification Safety Limit violation as it relates to the subject plant applications.

"On 8/28/2017 Cooper notified the NRC of a reportable condition under 10CFR Part 21. An Allen Bradley relay base model 700DC exhibited early failure after 133 hours of service. This relay, model 700DC, has been dedicated/qualified for multiple applications for various plants.

"The Allen Bradley 700DC series relay coil failed after 133 hours of service. This failure was determined by Cooper Nuclear Station to have been a component infant mortality likely caused by a manufacturing flaw that likely occurred due to a tensioning issue at the start of the coil wire winding process. Failure of the coil will result in failure of the relay, which could result in a safety hazard.

"Nutherm International, Inc. has concluded its review of all procurements of the 700DC series relays that use the coil in question and have found forty-nine (49) units shipped to customers which could potentially have this defect: Nebraska Public Power Cooper Nuclear Station and Indiana Michigan Power Company Donald C. Cook Nuclear Plant.

"Initial actions of determining the units affected were completed 8/30/2017. The impacted customers were notified of this condition 8/30/2017. Nutherm International, Inc. does not have sufficient information to determine this condition would, or has, created a Substantial Safety Hazard or would have created a Technical Specification Safety Limit violation as it relates to the subject plant applications. Nutherm has no current orders for these units and has no units in stock. No further actions will be taken at this time.

"This issue has been identified as a 'component infant mortality' failure caused by a manufacturing flaw. The manufacturing flaw appears to be a random failure and was identified by Cooper Nuclear Station as likely to have occurred due to a tensioning issue at the start of the coil wire winding process. Failure of the coil would be expected to occur within a few days of operation. The units that have been installed and in operation for more than two months could be considered to not contain this random manufacturing flaw."

Point of Contact: Thomas Sterbis - 618-244-6000

See also NRC event: 52934

TECHNICAL SPECIFICATION REQUIRED SHUTDOWN

"On August 22, 2017 at 2321 hours, Grand Gulf Nuclear Station entered Technical Specification conditions for three Limiting Condition for Operations (LCOs) not met due to Residual Heat Removal 'A' (RHR 'A') being declared inoperable.

"LCOs not met:
1) 3.5.1 for one low pressure ECCS [Emergency Core Cooling System] injection/spray subsystem.
2) 3.6.1.7 for one RHR containment spray subsystem, and
3) 3.6.2.3 for one RHR suppression pool cooling subsystem.

"The station has made the decision to shutdown the plant based on the results of troubleshooting performed on the RHR 'A' pump. The restoration of RHR 'A' pump will not be completed prior to the end of the 7 day LCO completion time.

"Grand Gulf Nuclear Station initiated plant shutdown required by Technical Specifications 3.5.1, 3.6.1.7, and 3.6.2.3 at 1200 hours CDT on 08/29/2017 due to expected restoration of RHR 'A' exceeding the completion time of 7 days prior to restoring operability."

The licensee notified the NRC Resident Inspector.