ML20212B023
| ML20212B023 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry, Grand Gulf, Cooper, Prairie Island, Turkey Point, Duane Arnold, Farley, San Onofre, Zion, 05000000 |
| Issue date: | 12/17/1986 |
| From: | Hebdon F NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Jordan E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| Shared Package | |
| ML20212B028 | List: |
| References | |
| AEOD-E612, NUDOCS 8612290129 | |
| Download: ML20212B023 (3) | |
Text
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<, y December 17, 1986 AE0D/E612 MEMORANDUM FOR: Edward L. Jordan, Director Division of Emergency Preparedness and. Engineering Response Office of Inspection and Enforcement FROM:
Frederick J. Hebdon, Deputy Director Office for Analysis and Evaluation of Operational Data
SUBJECT:
EMERGENCY DIESEL GENERATOR COMPONENT FAILURES DUE TO VIBRATION Enclosed is an AE0D engineering evaluation report concerning cracking of small bore piping that resulted in inoperability of emergency diesel generators (EDGs). The cracked lines were found in EDG lube oil, fuel oil and cooling water systems. The piping cracks, which were caused by cyclic fatigue that resulted from engine-induced vibration, were not detected by the inservice inspection or the preoperational testing program for the piping. The failures were only discovered after the cracks propagated completely through the tube wall and fluid was observed leaking from the pipes.
In one of the events identified, a fire occurred as lube oil spraying from a cracked lube line was ignited by the hot exhaust piping of the diesel engine.
Our review indicates that fatigue failures induced by steady-state operation, such as plant equipment or engine-induced vibration, are not normally analyzed in the original piping design. A more complete design review is typically done only after related problems are identified during plant operation. Often the problem is not detected until a leak occurs. Such leaks could result in sudden disabling of the EDGs when needed and could adversely affect a safe plant shutdown in the event of a loss of offsite power.
The cracked pipes in four of the events identified during the review were made of either copper or brass material, which are considered to be vulnerable to cracking due to vibrational loads.
In each case the licensee replaced the piping with piping made of steel.
In addition to the eight events included in the above review, we have identified a very recent related event which occurred in Prairie Island I on September 8, 1986.
In this event a small brass oil line burst during e612290129 861217 PDR ADOCK 05000282 S
o Edward L. Jordan
-2 operability testing of a EDG, The EDG was subsequently declared inoperable and the ruptured brass tubing was replaced with a stainless steel line. The cause of the failure was due to engine vibration which resulted in work-hardening of the brass tubing and eventual brittle fracture. This event further supports the findings, conclusions, and suggestion contained in this report.
In view of this safety concern, it is suggested that IE issue an information notice to inform licensees of the potential safety concern of fatigue cracks in fuel oil, lube uil and cooling lines associated with EDGs.
If you or your staff have any questions concerning the enclosed engineering evaluation report, please contact Chuck Hsu of my staff on extension x24443.
l Original Signed By Frederick J. Hebdon, Deputy Director Office for Analysis and Evaluation of Operational Data
Enclosure:
As Stated cc w/ enclosure:
DISTRIBUTION:
J. Taylor, IE PDR R. Baer, IE AE0D CF J. Henderson, IE AE0D SF D. Dilanni, NRR ROAB CF J. Norris, NRR ROAB SF D. Humenansky, OCM CHsu M. Beaumont, W Plam C. Brinkman, UE SRubin i
R. Borsum, B&W WBlack i
L. Gifford, GE WLanning CJHeltemes FHebdon j
t
- See next sheet for previous concurrence
! 0FC
- ROAB
- ROAB:SC
- ROAB:BC
- AE00:DD
- AE0D D
' NAME :CHsu:nc
- MChiramal
- SRubin
- FHebdon
- Ct itemes DATE :12/11/86 *
- 12/11/86*
- 12/12/86 *
- 12/15/86 *
- 12/11/86 OFFICIAL RECORD COPY i
4
Edward L. Jordan operability testing of a EDG. The EDG was subsequently declared operable and the ruptured brass tubing was replaced with a stainless ste line. The cause of the failure was due to engine vibration which resulte in work-i hardening of the brass tubing and eventual brittle fracture. This event further supports the findings, conclusions, and suggestion ontained in this report.
1 In view of this safety concern, it is suggested that issue an information notice to inform licensees of the potential safety c cern of fatigue cracks in fuel oil, lube oil and cooling lines associated ith EDGs.
If you or your staff have any questions concern g the enclosed engineering
~
evaluation report, please contact Chuck Hsu of y staff on extension x24443.
I Fr erick J. Hebdon, Deputy Director 0 fice for Analysis and Evaluation of Operational Data
Enclosure:
4 As Stated cc w/ enclosure:
DISTRIBUTION:
J. Taylor, IE PDR R. Baer, IE AE00 CF J. Henderson, IE AE0D SF D. Dilanni, NRR R0AB CF i
J. Norris, NRR R0AB SF CHsu Plam SRubin WBlack WLanning CJHeltemes FHebdon i
0FC :ROAB
- AEOD:DD
- AEOD:D
__:._______f__j, (ROAB:SC (,:ROAB:BC
__:____________:.________..:..___7 1
NAME :CHsu:nc
- MChiramal
- SRubin 7
- FHebdo
- CJHeltemes
_____:____________:____________:______ M 1
DATE :12/// /86
- 12/B/86
- 12/f2/86
- 12/15/86
- 12/ /86 OFFICIAL RECORD COPY I
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