05000338/LER-2003-001, From North Anna, Unit 1 Regarding Reactor Vessel Head Penetration Nozzle Leakage
| ML031200697 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 04/24/2003 |
| From: | Heacock D Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 03-180, NAPS:MPW LER 03-001-00 | |
| Download: ML031200697 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| 3382003001R00 - NRC Website | |
text
I OCFR50.73 Virginia Electric and Power Company North Anna Power Station P. O. Box 402 Mineral, Virginia 23117 April 24, 2003 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555-0001 Serial No.:
NAPS:
Docket No.:
License No.:
03-180 MPW 50-338 NPF-4
Dear Sirs:
Pursuant to 10CFR50.73, Virginia Electric and Power Company hereby submits the following Licensee Event Report applicable to North Anna Power Station Unit 1.
Report No. 50-338/2003-001-00 This report has been reviewed by the Station Nuclear Safety and Operating Committee and will be forwarded to the Management Safety Review Committee for its review.
Very truly yours,
/
2 Heacock 4 ce President
'.North Anna P6 r Station Enclosure Commitments contained in this letter: None cc: United States Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW, Suite 23 T85 Atlanta, Georgia 30303-8931 Mr. M. J. Morgan NRC Senior Resident Inspector North Anna Power Station
NRC FORM 366 U.S. NUCLEAR REGULATORY APPROVED BY OMB NO. 3150-0104 EXPIRES 7-31-2004 (7-2001)
NUCL MA MAONY the NRC may not conduct or sponsor, and a person Is not required to respond to,
_the Information collection.
FACILITY NAME (1)
DOCKET NUMBER (2)
PAGE (3)
NORTH ANNA POWER STATION, UNIT 1 05000 - 338 1 OF 3 TITLE (4)
Reactor Vessel Head Penetration Nozzle Leakage EVENT DA (5)
LER NUMBE (6)
REPORT DA E(I7)
OTHER FACILITIES INVOLVD (8)
MONTH DAY YEAR YEAR SEQUENTIAL REVISION MONTH DAY YEAR FACILITY NAME DOCUMENTNUMBER NUMBER NUMBER 05000-03 04 2003 2003
-- 001 -
00 04 24 2003 FACILITY NAME DOCUMENT NUMBER
_ ___I__I 05000-OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) (11)
MODE (9) 6 20.2201(b) 20.2203(aX3Xii) 50.73(sX2)XiXB) 50.73(aX2)(OxXA)
POWER 20.2201 (d) 20.2203(a)(4) 50.73(a)(2Xiii) 50.73(aX2Xx)
LEVEL (10) lv 20.2203(a)(1) 50.36(c)(IXIXA) 50.73(a)(2Xiv)(A) 73.71(a)(4) 20.2203(a)(2Xi) 50.36(c)(1 Xii)(A) 50.73(aX2XvXA) 73.71 (a)(5) 20.2203(a)(2X1i) 50.36(cX2) 50.73(aX2Xv)(B)
OTHER 20.2203(aX2Xiii) 50.46(a)(3Xii) 50.73(aX2Xv)(C)
Specify In Abstract below or 20.2203(aX2)(Iv) 50.73(a)(2XIXA) 50.73(aX2)(vXD)
In NRC Femrn 366A 20.2203(aX2)(v)
X 50.73(a)(2XIXB) 50.73(a)(2Xvii) 20.2203(aX2Xvi) 50.73(aX2XiXC) 50.73(a)(2Xviii)(A) 20.2203(aX3Xi)
X 50.73(aX2)(IIXA) 50.73(a)(2Xviii)(B)
LICENSEE CONTACT FOR THIS LER (12)
NAME I TELEPHONE NUMBER (Include Ak Code)
D. A. Heacock, Site Vice President I (540) 894-2101 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPO RT (13j
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE
._l ____l TO EPIX l
l l
TO EPIX B
l ll I_
II_
I I
I SUPPLEMENTAL REPORT EXPECTED (14)
EXPECTED MONTH DAY YEAR SUBMISSION YES (if yes, complete EXPECTED SUBMISSION DATE).
IX NO DATE (1) j j
ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)
On February 22, 2003, at 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br /> Unit I was ramped offline for a scheduled refueling outage. On March 4, 2003, at 0854 hours0.00988 days <br />0.237 hours <br />0.00141 weeks <br />3.24947e-4 months <br />, with Unit 1 defueled, an apparent reactor vessel head through-wall leak was noted during visual inspection of penetration 50. The reactor vessel head was being visually inspected at penetration 50 to follow up on inspection results from the previous outage in 2001. Penetration 50 was found to exhibit boric acid approximately one half inch in diameter at the lower side of the penetration-to-head transition. There was no sign of wastage on the reactor vessel head. This through wall leak has been assessed as a degradation of a principal safety barrier in accordance with 10 CFR 50.72(b)(3)(ii)(A). An 8-hour Non-Emergency Report was made to the NRC at 1033 hours0.012 days <br />0.287 hours <br />0.00171 weeks <br />3.930565e-4 months <br /> on March 4, 2003. No significant safety consequences resulted from this event since RCS unidentified leakage was well below Technical Specification limits. The health and safety of the public were not affected at any time during this event.
NRC FORM 366 (1-2001)
(If more space Is required, use additional copies of (If more space Is required, use additional copies of NRC Form 366.A) (17)
3.0 CAUSE
The apparent cause of the Penetration 50 leakage was hot-short cracking, which occurred during original fabrication of the reactor vessel head. The leakage was accelerated by primary water stress corrosion cracking.
4.0 IMMEDIATE CORRECTIVE ACTION(S)
An 8-hour Non-Emergency Report was made to the NRC at 1033 hours0.012 days <br />0.287 hours <br />0.00171 weeks <br />3.930565e-4 months <br /> on March 3, 2003.
5.0 ADDITIONAL CORRECTIVE ACTIONS
A management decision was made to replace the North Anna Unit I reactor head with one constructed of materials that are known to be more resistant to cracking rather than perform penetration repairs.
6.0 ACTIONS TO PREVENT RECURRENCE Future reactor vessel head inspections will be performed in accordance with our responses to NRC Bulletin 2002-02.
7.0 SIMILAR EVENTS
LER 50-339/02-001-00 documents the Unit 2 nozzle through-wall leakage of three reactor vessel head penetrations.
LER 50-339/01-003-00 and Supplemental LER 50-339/01-003-01 documents the Unit 2 nozzle through-wall leakage of three reactor vessel head penetrations.
LER 50-339/94-005-00 documents leakage on a nozzle weld on the seal injection line entering the "B" RCP thermal barrier housing. This line is part of the RCS pressure boundary leakage.
8.0 MANUFACTURERIMODEL NUMBER Rotterdam Dockyard Company/Serial Number 30662
9.0 ADDITIONAL INFORMATION
None