05000338/LER-2003-002, From North Anna Power Station, Unit 1 Regarding Entered Mode 4 with an Inoperable Containment Air Lock Due to Human Error
| ML031681285 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 06/05/2003 |
| From: | Heacock D Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 03-344 LER 03-002-00 | |
| Download: ML031681285 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3382003002R00 - NRC Website | |
text
1 OCFR50.73 Virginia Electric and Power Company North Anna Power Station P. O. Box 402 Mineral, Virginia 23117 June 5, 2003 U. S. Nuclear Regulatory Commission Attenfion: Document Control Desk Washington, D. C. 20555-0001 Serial No.:
NAPS:
Docket No.:
License No.:
Dear Sirs:
Pursuant to I OCFR50.73, Virginia Electric and Power Company hereby submits the following Licensee Event Report applicable to North Anna Power Station Unit 1.
Report No. 50-338/2003-002-00 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, D. A. Heacock, Site Vice President North Anna Power 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 03-344 MPW 50-338 NPF-4 I
APPROVED BY OMB NO. 3150-0104 EXPIRES 7-31-2004 NRC FORM 366 U.S. NUCLEAR REGULATORY the NRC maiy not conduct or sponsor, and a person is nt required to respond to.
the information collection.
FACILY NAME (1)
DOCKET NUMBR (2)
PAGE (3)
NORTH ANNA POWER STATION, UNIT 1 l 05000 - 338 l
1 OF 4 TrMLE (4)
Entered Mode 4 with an Inoperable Containment Air Lock Due to Human Error EVENT DATE (5)
LER NUMBE (6)
REPORT DATE (7)
OTHER FACILITIES INVOLVED (8)
MONTH DAY YER Y
SEQUENTIAL EVISION MOM DAY Y
FACILITY NAME DOCUMENT NUMBER
_OI~(rH D~r NUMBER NUMBER 05000-04 13 2003 2003
- - 002-00 06 05 2003 FACILIlYNMIE DOCUME NNMBER
___ 1 1 1 1
1~~~~~~~~~
OPERATING THIS REPORT IS SUBMITTED PURSUANTTOTHE REQUIREMENTS OF 10 CFR§: (Check sl that apply) (11)
MODE (9) 4 202201(b) 20.2203(aX3XII) 50.73(a)(2XH)(B) 50.73(aX2XIxXA)
POWER 20.2201(d) 20.2203(aX4) 50.73(aX2XIii) 50.73(aX2)(x)
LEVEL (10) 0%
20.2203(aXI)
=
50.36(cXIXIXA) 50.73(aX2XIvXA) 73.71(aX4) 20.2203(aX2XI) 50.36(cX1 )IXA) 50.73(aX2XvXA) 73.71 (aX5) 20.2203(aX2)(1) 50.36(cX2) 50.73(aX2XvXB)
OTHER 20.2203(aX2Xli) 50.46(aX3XiI) 50.73(aX2XvXC)
Specfy in Absbrl below or 20.2203(aX2Xiv)
=
50.73(aX2XiXA) 50.73(aX2XvXD) hi NRC Form 36A 20.2203(a.X2v)
X 50.73(aX2XIXB) 50.73(SX2Xvi) 20.2203(a)(2Xvi) 50.73(aX2XIXC) 50.73(aX2XvIiiXA) 20.2203(aX3Xi) 50.73(aX2XiiXA)
I5.73(aX2XvIiXB)
UCENSEE CONTACT FOR THIS LER (12)
NAME TELEPHONE NUMBER (Include Ae Code)
D. A. Heacock, Site Vice President 1 (540) 894-2101 COMPLETEONE UNEFOREACH COMPONENTFAILUREDESCRIBEDINTHISREPORT (13 CALUSE lSYSTEM l COMPONENT MANUFACTURER REPORTABLE
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE l_______
l__l__
TO EPIX l_l
_l_l_TO EPIX SUPPLEMENTAL REPORT EXPECTED (14)
XPECTED MONTH DAY YEAR I
I v I I
SUBMISSION YES (f yes, complete EXPECTED SUBMISSION DATE).
x XI NO l
DATE (15) j ABSTRACT (Limit to 1400 spaces, Le., approdmately 15 single-spaced typewritten lines) (16)
On April 13, 2003, at 1114 hours0.0129 days <br />0.309 hours <br />0.00184 weeks <br />4.23877e-4 months <br /> Unit 1 entered Mode 4 with an inoperable containment personnel air lock. Containment leakage testing was performed as part of the unit start-up activities following a refueling outage. The total containment personnel air lock leakage was identified at 22 standard cubic feet per hour (scfh) with a test procedure limit of <12.9 scfh. Technical Specificafion (TS) limit is <.05 La, which equates to < 15.22 scfh. The personnel air lock leakage of 22 scfh was factored into the total containment leakage. The total maximum containment leakage rate was then calculated at 42.32 scfh well below the acceptance criteria of <182.6 scfh. The requirements of Technical Specifications (TS) were not properly verified resulting in an incorrect assumption that the specified periodic test procedure acceptance leakage limits for the containment personnel air lock were administrative. As such, a condition prohibited by TS occurred and this event is reportable in accordance with I OCFR50.73(a)(2)(i)(B). The health and safety of the public were not affected at any time during this event.
NRC FORM 366 (1-2X1)
(ff more space Is required, use additonal copies of NRC Forn 366A) (17) 1.0 DESCRIPTION OF THE EVENT On April 13, 2003, at 0300 hours0.00347 days <br />0.0833 hours <br />4.960317e-4 weeks <br />1.1415e-4 months <br /> with Unit I in Mode 5, containment personnel air lock (EIIS System - NH, Component - AL) leakage testing was being performed as part of the start-up activities following a refueling outage. The total flow rate for the containment personnel air lock was measured at 22 standard cubic feet per hour (scfh). The periodic test procedure has a limit of < 12.9 scfh with a Technical Specification (TS) limit of <.05 L., which equates to < 15.22 scfh. Attempts were made to locate the leakage on the personnel air lock outer door and none were found. Attempts were then made to locate the leakage on the personnel air lock inner door without success since the containment was under vacuum. The measured value of 22 scfh was subsequently factored in to the total containment local leakage rate and the total maximum path leakage rate. A decision was made to continue with unit start-up activities since the total maximum leakage rate was calculated at 42.319 scfh well below the TS acceptance criteria of <182.6 scfh.
The Technical Specification (TS) require two containment airlocks (i.e., equipment airlock and personnel airlock) be operable in Modes 1 through 4. Both the inner and outer air lock doors must be operable for the airlock to be operable. The TS LCO 3.6.2 surveillance requirement delineates air lock leakage rate testing in accordance with the "Containment Leakage Rate Testing Program". The acceptance limits of the program,
<.05 L. which equates to < 15.22 scfh, are delineated in the TS Administrative Controls Section 5.5, Programs and Manuals. While evaluating the test results and TS requirements, the specific criteria for containment personnel air lock leakage was overlooked. The requirements of TS were not properly verified resulting in an incorrect assumption that the overall containment leakage value (total maximum path leakage) was the limit.
On April 13, 2003, at 1114 hours0.0129 days <br />0.309 hours <br />0.00184 weeks <br />4.23877e-4 months <br /> Unit 1 entered Mode 4 with an inoperable containment personnel air lock. This event is reportable in accordance with I OCFR50.73(a)(2)(i)(B) for a condition prohibited by TS.
2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS
No significant safety consequences resulted from this event since containment was operating under vacuum and no leakage escaped to the atmosphere. The total maximum leakage rate was calculated to be 42.319 scfh well below the acceptance criteria of
<182.6 scfh. The TS allow for continued operation indefinitely as long as an operable air lock door is: a) verified closed within one hour, b) locked within twenty four hours, and c) verified locked closed once every thirty one days.
Appendix J to 10 CFR 50, Primary Reactor Containment Leakage Testing for Water Cooled Power Reactors, does not delineate specific acceptance criteria limits for containment air locks but rather containment leakage as a whole. The design limit of (f more space s required, use additional copies of NRC Forn 366A) (17) allowable containment leakage during an accident is called La based on 0.1 percent of containment volume leakage per day. To allow margin for meeting the L limit, a fraction of that limit, < 0.6 La is used as the limit of the total local leak rate. As left maximum path measured leakage must be < 0.6 L. prior to entering a mode requiring containment integrity.
Since containment penetrations have double barriers, leakage is tracked in three categories: a) As Left Maximum Path Leakage, b) As Left Minimum Path Leakage, and c)
As Found Minimum Path Leakage. Maximum path leakage is the larger leak rate of two valves in series and minimum path leakage is the smaller leak rate of two valves in series.
Each of the three categories must be < 0.6 La and are applicable during different conditions such as start-up, refueling outages and operating. A running total is modified based on the measurement of new leakage sources and elimination of existing leaks by repair. The unit La is < 304.4 scfh and the < 0.6 La is < 182.6 scfh. The measured total local leak rate including instrument error for the Unit 1 containment was:
As Left Maximum Path Leakage 42.319 scfh As Left Minimum Path Leakage 19.023 scfh As Found Minimum Path Leakage 17.406 scfh The calculated Total Maximum Path Leakage of 42.319 scfh is well below the acceptance criteria of <182.6 scfh and as such, there were no 10 CFR 50 Appendix J mode holds.
3.0 CAUSE
The apparent cause is attributed to human error. The TS LCO 3.6.2 surveillance requirement delineates air lock leakage rate testing in accordance with the Containment Leakage Rate Testing Program'. The acceptance limits of the program are delineated in the TS Administrative Controls Section 5.5, Programs and Manuals. The requirements of TS were not properly verified resulting in an incorrect assumption that the containment personnel air lock leakage numbers specified in the periodic test procedure were administrative limits.
4.0 IMMEDIATE CORRECTIVE ACTION(S)
Upon discovery of the condition prohibited by TS a station deviation report was initiated.
At the time of discovery Unit I had already been placed in Mode 5 as a result of reactor coolant leakage from the number 4 core exit thermocouple nozzle assembly.
5.0 ADDITIONAL CORRECTIVE ACTIONS
Repairs were made to the containment personnel air lock inner door. Subsequent leakage rate testing was performed with satisfactory results.U.S. NUCLEAR REGULATORY COMMISSION (7-2001)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET LER NUMBER 6)
PAGE (3)
- ER I SEOUENTLAL iREVSION I
NUMBER NUMBER NORTH ANNA POWER STATION UNIT 1 05X0 - 338 2003
- - 002 -
00 4 OF4 NARRATE ff moe space Is required, use additional copies of NRC Fonn 366A) (17) 6.0 ACTIONS TO PREVENT RECURRENCE The periodic test procedures for containment personnel air lock leakage and total containment leakage testing are being revised to specifically reference TS Section 5.5 including a clarification that the limits for the containment personnel air lock are required by the TS and not an administrative limit.
7.0 SIMILAR EVENTS
None
8.0 ADDITIONAL INFORMATION
Unit 2 was not affected by this event. A review of Unit 2 containment personnel air lock leakage test results from the February 2003 start-up indicated 5.5 scfh.