05000482/LER-2002-001, Re Voluntary Report of Emergency Diesel Generator Heat Exchanger Tube Degradation
| ML020990127 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 03/25/2002 |
| From: | Jacobs D Wolf Creek |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| WO 02-0017 LER-02-001-00 | |
| Download: ML020990127 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded |
| 4822002001R00 - NRC Website | |
text
WV¶'LF CREEK
'NUCLEAR OPERATING CORPORATION Donna Jacobs Plant Manager MAR 2 5 2002 WO 02-0017 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
Subject:
Docket No. 50-482: Licensee Event Report 2002-001-00 Gentlemen:
The enclosed Licensee Event Report (LER) 2002-001-00 is being submitted voluntarily. This report pertains to Emergency Diesel Generator (EDG) heat exchanger tube degradation at Wolf Creek Generating Station (WCGS). Specific information is included with respect to eddy current testing programs, including the identification and disposition of test data results containing absolute drift indication (ADI), suspected dealloying (SDA), and tube pitting indications in admiralty brass EDG heat exchanger tubes. Wolf Creek Nuclear Operating Corporation (WCNOC) believes this information may be of generic interest to the nuclear industry.
No commitments are identified in this correspondence.
If you should have any questions regarding this submittal, please contact me at (620) 364-4246 or Mr. Tony Harris at (620) 364-4038.
Very truly yours, Don Jacobs DJ/cls Enclosure cc:
J. N. Donohew (NRC), w/e D. N. Graves (NRC), w/e E. W. Merschoff (NRC), wle Senior Resident Inspector (NRC), wle P.O. Box 411 / Burlington, KS 66839 Phone: (620) 364-8831 An Equal Opportunity Employer M/F/HCNVET
_iJRC FORM 366 U.S. NUCLEAR REGULATORY APPROVED BY OMB NO. 3150.0104 EXPIRES 7-31-2004 (7-2001)
COMMISSION
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE WOLF CREEK GENERATING STATION 05000482 1 OF 4
- 4. TITLE Voluntary Report of Emer ency Diesel Generator Heat Exchanger Tube Degradation
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED FACILITY NAME DOCKET NUMBER ISEQUENTIAL REV MO DAY YEAR YEAR NUBE R 9
NO MO DAY YEAR FACILITY NAME DOCKET NUMBER 01 04 2002 2002 -- 001
-- 00 03 25 2002
- 9. OPERATING 11 TWI-q
- PfPPT lqI lRMITTrflnP1
_ 20.2201 (b)_
20.2203(a)(3)(ii)
_ 50.73(a)(2)(ii)(B) 50.73(a)(2)(ix)(A)
- 10. POWER 20.2201(d) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(x)
LEVEL 100 20.2203(a)(1)
_ 50.36(c)(1)(i)(A)
_ 50.73(a)(2)(iv)(A) 73.71(a)(4) 20.2203(a)(2)(i) 50.36(c)(1)(ii)(A) 50.73(a)(2)(v)(A) 73.71(a)(5) a 20.2203(a)(2)(ii) 50.36(c)(2)
_ 50.73(a)(2)(v)(B)
X OTHER 20.2203(a)(2)(iii)
__50.46(a)(3)(ii)
__50.73(a)(2)(v)(C)
Specify in Abstract below or in 20.2203(a)(2)(iv) 50.73(a)(2)(i)(A)
__50.73 a )2) v() DR om36 20.2203(a)(2)(v)
__50.73(a)(2)(i)(B)
__50.73(a)(2)(vii) 20__203__________
__50.73(a)(2)(i)(C) 50.73(a)(2)(viii)(A) 0l-202203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73 a 2 Viii B
- 12. LICENSEE CONTACT FOR THIS LER NAME l TELEPHONE NUMBER (Include Area Code)
Karl A. (Tony) Harris, Manager Regulatory Affairs j
(620) 364-4038MANU-REPORTABLE I
MANU-REPORTABLE CAU SE SYSTEM COMPONENT FACTURER TO EPIX l
CAUSE
l
_SYSTEM COMPONENT FACTURER TO EPIX
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR YES (If yes, complete EXPECTED SUBMISSION DATE)
I X lNO DATE
ABSTRACT
This information is reported voluntarily appropriate to the guidance provided in NUREG 1022, "Event Reporting Guidelines 10 CFR 50.72 and 50.73," revision 2, section 2.7 "Voluntary Reporting."
Heat exchanger tube degradation was identified on both of Wolf Creeks Generating Station's (WCGS)
Emergency Diesel Generators (EDGs). WCGS initiated an investigation team to examine this issue. Although the team concluded the EDGs were operable at the time of discovery, heat exchangers on both EDGs were found to be in a degraded condition. Suspect tubes were plugged. The team determined that the Preventive Maintenance (PM) program in place during the mid1990s did not implement eddy current testing (ECT) to monitor structural integrity of EDG heat exchanger tubing. This condition monitoring is in addition to the thermal performance monitoring performed in response to NRC Generic Letter 89-13, "Service Water System Problems Affecting Safety-Related Equipment."
Specific information is included with respect to ECT programs, including the identification and disposition of test data containing absolute drift indication (ADI), suspected dealloying (SDA), and tube pitting indications in admiralty brass heat exchanger tubes.
Wolf Creek Nuclear Operating Corporation (WCNOC) believes this information may be of generic interest to the nuclear industry.
NRC FORM 366 (7-2001)
(If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) caused by high flow velocities in the tubing. As a result, all of the tubes were replaced in each of the heat exchangers during refueling outages from 1987 through 1991. In addition, a design change was implemented in 1990 to reduce heat exchanger flow rates and mitigate tube erosion problems.
Recommendations to monitor tube integrity (via ECT) following these tube replacements were not incorporated into the heat exchanger PM program. Since then, changes have been made to improve PM and monitoring programs for these and other important equipment. The incorporation of ECT testing for the EDG heat exchangers into the PM program was a result of these changes. It should be noted that the Generic Letter 89-13, "Service Water System Problems Affecting Safety-Related Equipment," program focuses on heat exchanger thermal performance, and does not specifically address tube structural integrity.
- 3) The apparent cause of the tubing degradation is dealloying of the admiralty brass heat exchanger tubing, exacerbated by erosion effects. This conclusion is based in part on results of the hardware failure analysis performed in 1990. WCNOC plans to pull and replace EDG heat exchanger tubes during Wolf Creek's upcoming refuel outage. The results of hardware failure analysis performed with the pulled tubes will be evaluated to validate and confirm this conclusion.
Corrective Actions
Immediate Actions:
Degraded tubes in the "A" and "B" EDGs were plugged to ensure future structural integrity. Subsequent evaluation determined that both EDGs were fully available to perform their safety function, and were operable, prior to plugging the heat exchanger tubes.
The investigation of this issue has led to the development of numerous corrective action items tracked within WCNOC's Corrective Action program. Among these are:
1 ) On January 11, 2002, WCGS plant management conducted site-wide stand-down meetings for clarifying expectations regarding nonconformance identification and resolution. Additional actions to improve recognition and processing of nonconformances have been specified.
- 2) In addition to incorporating ECT into the EDG heat exchanger PM program, additional actions to improve aspects of the PM program pertinent to this issue have been specified. These include improving detail in procedures that govern heat exchanger inspection, testing, and trending activities as well as establishing standard protocols for reviewing and dispositioning test ECT results.
- 3) WCNOC plans to pull and replace specific degraded tubes. Laboratory analyses of these degraded tubes will include destructive testing of some tubes. The results of this analysis will again be reviewed to evaluate the effectiveness of the design change implemented in 1990 to reduce heat exchanger flow rates and mitigate tube erosion problems, and should confirm the apparent cause for the heat exchanger tube degradation.
Safety Significance
The condition of the EDG heat exchanger tubes as described herein was of minimal actual safety significance. An evaluation performed for each heat exchanger indicates the safety function of the EDG system was not adversely impacted.