(Closed) LERs 05000369/2014-001-00 and 05000369/2014-001-01,
Condition Prohibited by Technical Specifications (TS) due to Emergency Diesel
Generator 1B
Failure
a. Inspection Scope
This URI was initiated for the NRC issuance of Notice of
Enforcement Discretion (NOED) 14-2-002, dated August 27, 2014, in order to review
the circumstances that led to the NOED request to determine if any performance
deficiencies or violations contributed to the need for the NOED. The inspectors
reviewed the licensee’s LERs associated with the failure of the cylinder 5L
intake valve stem on the 1B EDG, the licensee’s root cause investigation, and
their corrective actions to address the failure. Previous evaluation of the
accuracy and details of the licensee’s request for the NRC to exercise
discretion not to enforce compliance with the required action completion time for
TS Limiting Condition for Operability (LCO) 3.8.1 to allow extra time for the
engine to be repaired was documented in NRC Integrated Inspection Report
05000369, 370/2014005.
The licensee established a formal root cause team consisting
of six team members, including an outside industry diesel expert, to evaluate
the failure and to determine applicable corrective actions. An extensive metallurgical
laboratory analysis was conducted on the failed parts and further analysis was conducted
by the disassembly of other cylinder heads on the 1B EDG during the subsequent
fall 2014 refueling outage when the engine was removed from service. The inspectors
found the licensee’s root cause evaluation to be detailed and exhaustive. The licensee
determined the cause of the 1B
EDG cylinder 5L intake valve failure was due to
the combined effects of three inlet valve sub-parts which were manufactured by
a third party supplier outside of the original equipment manufacturer (OEM)
(i.e., Norberg) specified tolerances. These manufacturing discrepancies
included: 1) the inlet valve stem hardness/tensile strength was below
specifications, 2) the hydraulic valve lash adjuster, which dampens the force between
the intake valve and its seat, did not function properly due internal clearances
being out-of-specification, and 3) the inlet valve spit rings, connecting the
valve stem upper end to its rocker arm, was found with a larger radius. The
combined effects of these out of tolerances resulted in inlet valve stem
stresses beyond the endurance limit and subsequent valve failure due to high
cycle fatigue.
The licensee implemented a number of corrective actions to
address the causal factors identified. Actions were taken to place a hold on
the procurement of the three out of tolerance components until the EDG parts
procurement specifications were revised. The revision would add additional
vendor verifications that the components meet the original Nordberg
specifications. To address the immediate extent of condition to limit the vulnerability
of similar cylinder components being out of tolerance, the licensee reviewed cylinder
vibration and ultrasonic signature testing of each of the cylinders of all four
EDGs to detect any inlet valve closure anomalies. In addition, during the Fall
2014 refueling outage, both the 1B and 1A EDGs were inspected to ensure no
similar out of tolerance components were installed. Similar inspections are
planned for the remaining 2A and 2B EDGs. In the interim, the licensee plans to
continue conducting periodic cylinder performance signature testing to detect any
abnormal change in cylinder performance. The inspectors verified that an
adequate extent of condition review was performed for all EDGs, and concluded
that there were no licensee performance deficiencies associated with the August
18, 2014, 1B EDG failure. This URI and associated LERs are closed.
b. Findings
No findings were identified.
Tim
Talked to the McGuire senior resident for about an hour today over this LER. He was a inspector for twenty five years. Couldn't get him to end the conversation. This is the LER:
LER 2014-01
Components inside the DG failed leading to a shutdown (Aug 2014). McGuire and Brunswick are the only plants in the USA who sports Nordberg DGs. Nordberg went out of business. Basically Duke bought the remaining shell of a company, mostly for the paperwork to support their DGs. They don’t have a typical repair parts stream…they contract to get replacement parts on their own.
I believe these replacement parts came from an ocean transportation company who owns big ships according to the resident. Seems old and obsolete Nordberg DG engines are popular in ocean shipping. The NRC is going to violate them in the future. The machine failed in Aug 2014 and the NRC still can't make their mind up to charge them or not.
"The cause of the EDG 1 B cylinder 5L failure is high cycle fatigue of the inlet valve due to the combined effects of three inlet valve train parts which were manufactured outside of original equipment manufacturer (OEM) specified tolerances.
The following factors caused the 5L inlet valve failure:
* Inlet valve stem hardness/strength below specification
* Hydraulic lash adjuster internal inadequate clearance
- Inlet valve keeper inadequate upper ID radius and thickness
Interaction of the above factors subjected the cylinder 5L inlet valve to forces beyond the design and endurance limit. Evidence of inadequate manufacturing was confirmed by inspection, measurement, and testing of the EDG 1 B cylinder 5L inlet valve train components. No single factor on its own can cause an inlet valve failure. A combination of the above factors created the conditions necessary for a failure of the inlet valve from high cycle fatigue over a relatively long time period. EDG 1 B operated for approximately 13 years with the out of tolerance parts. All of the above parts issues were created during manufacturing by inadequate adherence to original Nordberg specifications for materials and tolerances by a third party supplier that is no longer in operation."
I consider not having a traditional manufacturing company backing up these machines as an un-reviewed safety issue. I told the inspector you got two separate parts found to not meet manufacture specs…how can you trust all the other parts. It got by Duke's QA and their black market parts company is supposed to have nuclear grade QA. Duke has proven themselves as not being a good owner of a DG manufacturing company. You got to test a representative sample of replacement parts to see it them meet specs( they are). I told the inspector making a plant engineer basically playing manufacturer and ordering the manufacturing of parts, plant or corporate engineering isn’t designed for that. It eats up engineering resources and it might cause them not to watch other problems.
I posed the question, well, why can’t you order them to replace all the dgs with new machines. Get a giant manufacture with large engineering services on their machines and the replacement parts traditional stream. He says it is impossible, the specific DGs are integral to the licensing of the plant. Even putting in new machines, it wouldn’t be the original quality. What bs! He said it would be cheaper building a new plant than ripping out an obsolete dg and installing an identical or better dg. If a dg fails in a way it can't be used again...it means the plant would have to permanently shutdown.
He says that is why the industry has never changed out not even one dg in all of the history.
They could do as a LAR…it certainly is a lot smaller job that replacing SGs.
The resident brought in NRR and other staff…because the parts had an inadequate pedigree.They really have no idea where the parts came from and they are worried they come from a Chinese fraudulent parts sweat shop?
He was vaguely talking about Duke installing non-nuclear grade DGs outside the building to compensate for the reduced quality with their Nordberg DGs. The Nordbergs would still be used and operational…but some amount of outside non nuclear grade capacity would be in standby in case of failure. I told him don’t worry about in the end, risk perspectives will say it is risk insignificant. He doesn't get my humor.
I found it suspicious as hell I couldn't get him to hang up?
Mike
Duke owns Brunswick today.
November 24, 2009:NRC SPECIAL INSPECTION 05000325/2009011 AND 05000324/2009011
"Brunswick and McGuire are the only two operators in the
United States that utilize Nordberg EDGs in nuclear safety-related applications.
Progress Energy and Duke Power Corporation are partnered with ESI as owners of the
Nordberg nuclear EDG design and share information regarding the Nordberg EDGs.
This provides Progress Energy with the availability of shared resources and
access to a spare Nordberg diesel at the McGuire nuclear plant for training and
troubleshooting. Also, operating experience gained from McGuire provides immediate
feedback on key diesel issues or previous
maintenance activities."
https://adamswebsearch2.nrc.gov/webSearch2/view?AccessionNumber=ML15005A044
LER 2014-01-01: Condition Prohibited by Technical Specifications (TS) due to Emer ency Diesel Generator 1 B Failure.
Excepts from the LER: