PART 21 - POTENTIAL DEFECT IN VICKERS VOLTAGE REGULATOR SYSTEM
The following summary was provided in the Part 21 report:
"ESI [Engine Systems Inc.] was notified on December 6, 2018 of a potential issue with saturable reactors (also referred to as magnetic amplifiers) supplied to Monticello Nuclear Generating Plant. ESI provided the reactors as like-for-like replacements for the existing magnetics of the original Vickers voltage regulator and static exciter. During system testing performed by Monticello at another vendor facility, issues with the static excitation system were identified which prevented proper control of the generator field current. Troubleshooting identified several potential causes and ESI believes there may be a potential deficiency in the saturable reactor, P/N 8408218-ESI.
"This component is integral to operability of the Vickers style voltage regulator and static exciter systems used on many emergency diesel generator sets in the nuclear industry. A deficiency in the reactor would adversely affect the ability to control generator output voltage and therefore adversely affect emergency diesel generator set performance.
"ESI is in the process of performing additional testing and analysis at the transformer manufacturer's facility to determine if a deficiency exists in this component. ESI is unable to complete an evaluation within the 60-day requirement."
ESI has supplied the part to NRC licensees but, to ESI's knowledge, none of the components have been installed. ESI is notifying each customer and advising not to install the reactors until the evaluation is complete.
This Part 21 Report affects the following licensees:
Surry Power Station
Turkey Point Nuclear Generating Station
Monticello Nuclear Generating Station
Point of Contact: Dan Roberts
Telephone: 525-977-2720
Fax: 252-446-1134
175 Freight Road, Rocky Mount, NC 27804
* * * UPDATE ON 3/21/19 AT 1448 EST FROM DAN ROBERTS TO JEFFREY WHITED * * *
The following is a summary of the information provided by the vendor via fax:
On January 24, 2019, Engine Systems Inc. (ESI) issued interim report 10 CFR 21-0124-INT, rev.0 regarding an identified deviation for which ESI was unable to complete an evaluation within the 60-day requirement. Per the interim report, ESI committed to complete the evaluation by March 22, 2019. The evaluation is now complete and the deviation is determined to be reportable in accordance with 10 CFR Part 21.
Identification of the basic component supplied within the United States which fails to comply or contains a defect and nature of the defect:
Part Number (P/N) 8408213-ESI: Power Current Transformer - Insufficient core gap.
P/N 8408218-ESI: Saturable Reactor - Differences in coil winding and core lamination from original design.
P/N 8411387-ESI: Excitation Power Transformer - Incorrect polarity
Each of the devices listed above provide a specific function within the static exciter of a Vickers voltage regulator system. The exciter supplies DC excitation current to the generator field based on input from the voltage regulator. Failure of any one of the components to perform correctly will negatively impact excitation current supplied to the generator field which in turn directly affects generator output. Therefore, failure of any one of the components may prevent the emergency diesel generator from carrying its associated safety-related loads.
The corrective action which has been, is being, or will be taken:
P/N 8408213: Return to ESI for rework. The part required additional insulating material to increase the core gap.
P/N 8408218: Return to ESI for replacement.
P/N 8411387: Return to ESI for rework to have primary terminal markings re-labeled.
Contacts:
John Kriesel
Engineering Manager
Engine Systems Inc.
175 Freight Rd.
Rocky Mount, NC 27804
Dan Roberts
Quality Manager
Engine Systems Inc.
175 Freight Rd.
Rocky Mount, NC 27804
Affected facilities still include Monticello, Turkey Point, and Surry.
Notified R2DO (Montgomery) and R3DO (McCraw), Part 21/50.55 Reactors group via e-mail. |