05000413/LER-2004-001, Regarding Gas Accumulation in Centrifugal Charging Pump Suction Piping
| ML040840514 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 03/15/2004 |
| From: | Jamil D Duke Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 04-001-00 | |
| Download: ML040840514 (12) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2) 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 |
| 4132004001R00 - NRC Website | |
text
1, V Duke rJPowers A Duke Energy Company D.M. JAMIL Vice President Duke Power Catawba Nuclear Station 4800 Concord Rd. / CNO1 VP York, SC 29745-9635 803 831 4251 803 831 3221 fax March 15, 2004 U. S. Nuclear Regulatory Commission ATTENTION:
Document Control Desk Washington, DC 20555-0001
SUBJECT:
Duke Energy Corporation Catawba Nuclear Station Unit 1 Docket Nos. 50-413 Licensee Event Report 413/2004-001 Revision 0 Attached please find Licensee Event Report 413/2004-001 Revision 0, entitled "Gas Accumulation in Centrifugal Charging Pump Suction Piping". A supplemental report is scheduled to be submitted June 15, 2004 to provide additional information for the root cause investigation and
safety analysis
This report does not contain any NRC commitments.
Questions regarding this Licensee Event Report should be directed to G. K. Strickland at 803-831-3585.
Sincerely, D. M. Jamil Attachment
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_), t::5 www. duke-energy. corn
U.S. Nuclear Regulatory Commission March 15, 2004 Page 2 xc:
L. A. Reyes U. S. Nuclear Regulatory Commission Regional Administrator, Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, GA 30303 S. E. Peters (addressee only)
NRC Project Manager (CNS)
U. S. Nuclear Regulatory Commission Mail Stop 0-8 G9 Washington, DC 20555-0001 E. F. Guthrie Senior Resident Inspector (CNS)
U. S. Nuclear Regulatory Commission Catawba Nuclear Site INPO Records Center 700 Galleria Place Atlanta, GA 30339-5957
NWC FORM 366 U.S. NUCLEAR REGULATORY APPROVED BY OMB NO. 3150-0104 EXPIRES 7-31-2004 (7-2001)
COMMISSION digits/characters oreach block) the NRC may not conduct or sponsor, and a person Is not required to respond to, the
_________________________________________________infnrmstinn emi11a'tion
- 3. PAGE Catawba Nuclear Station, Unit 1 05000 413 1 OF 10
- 4. TITLE Gas Accumulation in Centrifugal Charging Pump Suction Piping
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YAI RV FACILITY NAME DOCKET NUMBER MO DAY YEAR YEAR NUMBER NO MO DAY YEAR FACILITY NAME DOCKET NUMBER 01 14 2004 2004 001 00 03 15 2004
- 9. OPERATING 11.THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR : ( heck all that apply)
MODE 1
20.2201 (b) 20.2203(a)(3)(ii) x 50.73(a)(2)(0i)(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)
X 50.73(a)(2)(v)(A) 73.71a)(5) 20.2203(a)(2)(fi)
_ 50.36(c)(2) 50.73(a)(2)(v)(B)
TE Abstract below 20.2203(a)(2)(iii) 50.46(a)(3)(ii) 50.73(a)(2)(v)(C) or In
Abstract
On January 14, 2004 gas was discovered at the suction piping of the centrifugal charging pumps. Due to the lack of a firm bases to support operability, Engineering conservatively concluded that the gas volume was greater than the acceptance criteria necessary for pump operability. This condition resulted in the unit being in an unanalyzed condition. The system was vented and the pumps restored to operable condition.
One of the causes of the gas accumulation was reverse leakage from relief valve 1NV235 on the emergency boration line. The relief valve has been replaced.
Additional troubleshooting is in progress to identify additional sources of gas accumulation. The troubleshooting results will be provided with the June 15, 2004 submittal. The submittal will also include the engineering analysis to determine whether the centrifugal charging pumps were operable.
During the event investigation, the charging pump suction piping was frequently monitored and vented to maintain the system filled with water. No pump degradation was observed. No plant transient occurred that relied upon the safety function of the charging pumps.
NRC FORM 366 (7-2001)
N9C =
(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 (If more space is required, use additional copies of NRC Foirm 366A) (17) makeup water pump 1B maintenance. Investigation of gas intrusion source continued.
Power restored to valve 1ND-28A and TS 3.5.2 exited after completion of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> without significant voids in suction piping. Ultrasonic testing was continued in order to closely monitor gas voids in the charging pump suction piping.
01/19/04 01/19/04 01/19/04 01/19/ 04 01/19/04 01/19/04 to 01/22/ 04 0350 Gas void discovered at 1NV860 using ultrasonic testing.
0430 TS 3.0.3 entered for both trains of ECCS inoperable.
0506 TS 3.0.3 exited after gas vented at 1NV860.
0715 Valve 1ND-28A de-energized.
The 72-hour action statement for TS 3.5.2 entered for one train of ECCS inoperable.
1123 8-hour phone notification to NRC completed.
Investigation of gas accumulation continued.
Frequent ultrasonic testing (UT) of suction piping continued to closely monitor gas accumulation. Gas periodically vented to maintain the piping filled.
Source of gas accumulation not identified and system determined operable with compensatory measure established to maintain the piping filled and vented. One of the actions included isolation of the primary sample purge line connected to the volume control tank relief valve header.
01/22/04 0707 Power restored to valve 1ND-28A and TS 3.5.2 exited with both trains of ECCS operable.
No significant amount of gas identified after TS 3.5.2 exited on 1/22/04.
NWC FORM.366AU.S. NUCLEAR REGULATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
DOCKET (2)
FACILITY NAME (1)
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LER NUMBER (6)
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SEQUENTIAL REVISION YEAR NUMBER I NUMBER Catawba Nuclear Station, Unit 1 05000413 2004 -
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OF 10 NARRATIVE (If more space is required, use additional copies of (if more space is required, use additional copies of NRC Fonn 366A) (17) have fully closed. Check valve 1NV234 would have had to leak in the backward direction in order for relief valve 1NV235 to lift during emergency core cooling system check valve testing.
The review of the valve maintenance activities, check valve testing procedures, or plant equipment monitoring has not identified any performance deficiencies.
CORRECTIVE ACTIONS
Immediate:
- 1. Venting frequency increased upon initial discovery of gas accumulation.
- 2. Ultrasonic testing conducted at the charging pump suction piping to monitor for gas accumulation. Gas periodically vented to maintain system filled.
- 3. Failure investigation team assembled to determine the cause of gas accumulation.
- 4. Compensatory measures established to maintain the system operable. Compensatory measures included monitoring of the suction piping and temporary isolation of the primary sample purge line.
Subsequent:
- 1. One source of gas accumulation identified from relief valve 1NV235. The relief valve was replaced.
2.Unit 2 evaluated and determined to not have the same concern as the Unit 1 gas event due to the relief valve header pipe configuration.
Planned:
- 1. Relocate Unit 1 primary sample purge line connection to the relief valve header.
NR: FORM.366AU.S. NUCLEAR REGULATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
DOCKET (2)
FACILITY NAME (1)
NUMBER (2)
LER NUMBER (6)
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- - NUMBER INUMBER Catawba Nuclear Station, Unit 1 05000413 2004 001 -
00 8
OF 10 NARRATIVE (if more space Is required, use additional copies of (If more space is required, use additional copies of NRC Fofm 366A) (17)
The A-train charging pump suction has several of the same attributes as the B-train pump with the exception that the suction is in the flow stream of the common header. The A-train suction has several elbows and is approximately five feet below the common header. Absent a detailed flow calculation, the A-train pump was conservatively determined to be inoperable on 1/7/04, 1/14/04, and 1/19/04.
The gas accumulated in the suction piping was observed to be stationary during plant operations and for normal system flow rates of approximately 100 gpm. A suction flow rate of 200 gpm or higher was estimated to be necessary to sweep the gas into the pump.
However, absent a detailed flow calculation, both charging pumps were conservatively considered inoperable on 1/14/04.
An independent, detailed flow evaluation is being conducted to determine the amount of gas required to render one and two pumps inoperable. The results of the flow analysis will be used to quantitatively determine the safety significance of the event. The flow analysis may also change the event reporting criteria. A revision to the event report is anticipated by June 15, 2004.
ADDITIONAL INFORMATION
Within the last three years, no other LERs occurred at Catawba involving gas accumulation in the charging pump suction. Therefore, this event was determined to be non-recurring in nature.
A review of industry operating experience indicates that gas intrusion is an industry concern and events have been identified at other sites. However, the Catawba event is a new, previously unidentified failure mechanism for gas introduction into the charging pump suction. Therefore, this event could not have been prevented from the review of operating experience.
Energy Industry Identification System (EIIS) codes are identified in the text as [EIIS: XX]. This event is considered reportable to the Equipment Performance and Information Exchange (EPIX) program.
NRC FORM.366AU.S. NUCLEAR REGULATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
DOCKET (2)
FACILITY NAME (1)
NUMBER (2)
LER NUMBER (6)
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I SEQUENTIAL I REVISION 1YEAR NUMBER NUMBER Catawba Nuclear Station, Unit 1 05000413 2004 001 -
00 10 OF 10 NARRATIVE (if more space is required, use additional copies of NRC Form 366A) (17)
This event met the reporting criteria of 10 CFR 50.73 (a) (2) (v) and therefore will be recorded under the NRC Performance Indicators for Unit 1 as a Safety System Functional Failure.
There were no releases of radioactive materials, radiation exposures or personnel injuries associated with this event.