ML021050340
| ML021050340 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 04/02/2002 |
| From: | Witt W AmerenUE |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| ULNRC-4632 NRC-02-003-00 | |
| Download: ML021050340 (6) | |
Text
Union Electric Callaway Plant PO Box 620 Fulton, MO 65251 April 2, 2002 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop P1-137 Washington, DC 20555-0001 ULNRC-4632 WAm7erwir 0 1UF Gentlemen:
DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 UNION ELECTRIC CO.
FACILITY OPERATING LICENSE NPF-30 LICENSEE EVENT REPORT 2002-003-00 Auxiliary Feedwater Valve Inoperable due to faulty electronic circuit board.
The enclosed licensee event report is submitted in accordance with 1 OCFR50.73(a)(2)(i)(B) to report an Inoperable Auxiliary Feedwater Valve due to the failure of an electronic circuit board. The Inoperable Auxiliary Feedwater Valve rendered the respective train of Auxiliary Feedwater Inoperable for a period longer than allowed by Technical Specifications.
Warren A. Witt Manager, Callaway Plant WAW/ewh/glw Enclosure
<. 1
a subsidiary of Ameren Corporation
ULNRC-4632 April 1, 2002 Page 2 cc:
Mr. Ellis W. Merschoff Regional Administrator U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Jack N. Donohew (2 copies)
Licensing Project Manager, Callaway Plant Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 7E1 Washington, DC 20555-2738 Manager, Electric Department Missouri Public Service Commission PO Box 360 Jefferson City, MO 65102 Mr. John O'Neill Shaw, Pittman, Potts & Trowbridge 2300 N. Street N.W.
Washington, DC 20037 Records Center Institute of Nuclear Power Operations 700 Galleria Parkway Atlanta, GA 30339 Mr. Scott Bauer Regulatory Affairs Palo Verde Nuclear Generating Station P.O. Box 52034, Mail Station 7636 Phoenix, AZ 85072-2034 Mr. Scott Head Supervisor, Licensing South Texas Project NOC Mail Code N5014 P.O. Box 289 Wadsworth, TX 77483 Mr. Dennis Buschbaum Comanche Peak SES P.O. Box 1002 Glen Rose, TX 76043 Mr. Pat Nugent Supervisor, Licensing Pacific Gas & Electric Mail Stop 104/5/536 P.O. Box 56 Avila Beach, CA 93424
NRC FORM 366 U.S. NUCLEAR REGULATORY APPROVED BY OMB NO. 3150-0104 (7-2001)
COMMISSION Estimated burden per response to comply with this mandatory information collection request: 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the Records LICENSEE EVENT REPORT (LER)
Management Branch (T-6 E6), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to bjsl@nrc.gov, and to the Desk Officer, Office of (See reverse for required number of Information and Regulatory Affairs, NEOB-1 0202 (3150-0104), Office of Management and digits/characters for each block)
Budget, Washington, DC 20503. If a means used to impose information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITY NAME
- 2. DOCKET NUMBER
- 3. PAGE CALLAWAY PLANT UNIT 1 05000 483 1 OF 4
- 4. TITLE Auxiliary Feedwater Valve Ino erable due to faulty electronic circuit board.
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED FACILITY NAME DOCKET NUMBER SEQUENTIAL l REV MO DAY YEAR YEAR NUMBER NO MO DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 2
7 2002 2002 -
003 - 00 4
2 2002 _
05000
- 9. OPERATING
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR a: (Check all that apply)
MODE 4 _
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 0
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) 20 :f0 tX;0000i:.2203(a)(2)(ii) 50.36(c)(2)
__ 50.73(a)(2)(v)(B)
OTHER 0 4 : 0 y;! pt:20.2203(a)(2)(iii)
__ 50.46(a)(3)(ii)
L 50.73(a)(2)(v)(C)
NRcif FnAsrctblworm 366 20.2203(a)(2)(iy) 50.73(a)(2)(i)(A)
_50.73(a)(2)(v)(D)
NR_ Fr_36 20.2203(a)(2)(v)
X 50.73(a)(2)(i)(B) 50.73(a)(2)(vii)
I 20.2203(a)(2)(vi) 50.73(a)(2)(i)(C) 50.73(a)(2)(viii)(A) 20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(B)
- 12. LICENSEE CONTACT FOR THIS LER NAME TELEPHONE NUMBER (Include Area Code)
MARK A. REIDMEYER l
(573) 676-4306
- 13. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT MANU-REPORTABLE I MANU-REPORTABLE CAUSE SYSTEM COMPONENT FACTURER TO EPIX
-CAUSE SYSTEM COMPONENT FACTURER TO EPIX X
BA FCV M120 Y
__lll
- 14. SUPPLEMENTAL REPORT EXPECTED
[
- 15. EXPECTED MONTH DAY YEAR YES (If yes, complete EXPECTED SUBMISSION DATE)
X NO SUBMISSION
- 16. ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On 2/6/02, with Callaway Plant in Mode 4, 0 percent reactor power, a Modification package was completed that reduced the flow control setpoints for Auxiliary Feedwater (AFW) flow control valves. This modification was implemented to reduce full flow on the Motor Driven Auxiliary Feedwater (MDAFW) pumps to prevent reaching run-out conditions.
On 2/7/02, at approximately 0950, during the performance of a retest procedure to verify proper valve operation, AFW flow control valve, ALHV001 1, failed to reduce and control flow at setpoint. Troubleshooting revealed a faulty electronic circuit card in the flow control circuit. After this card was replaced on 2/8/02, ALHV001 1 performed satisfactorily. A review of past test data revealed that this problem first occurred on 5/15/01 during a retest on a different AFW flow control valve. ALHV001 1 was not directly associated with the 5/15/01 retest document and the unsatisfactory data was not detected.
This past unsatisfactory data indicated that ALHV001 1, and thus "A" train of Auxiliary Feedwater, was inoperable from 5/15/01 until 2/1/02 when Callaway Plant entered Mode 4 and Auxiliary Feedwater was no longer required per Technical Specification 3.7.5.
NRC FORM 366 (7-2001)
NRC FORM 366AU.S. NUCLEAR REGULATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
DOCKET (2)
FACILITY NAME (1)
NUMBER (2)
LER NUMBER (6)
PAGE (3) lSEQUENTIAL IREVISION Callaway Plant Unit 1 YEAR I
NUMBER NUMBER 05000483 2002 003 00 2
OF 4
NARRATIVE (If more space is required, use additional copies of NRC Form 366A) (17)
I.
DESCRIPTION OF THE REPORTABLE EVENT A. REPORTABLE EVENT CLASSIFICATION This event is reportable under I0CFR50.73(a)(2)(i)(B), a condition prohibited by Technical Specifications (T/S).
B. PLANT OPERATING CONDITIONS PRIOR TO THE EVENT On 2/7/02, Callaway Plant was shutdown in Mode 4 at 0 percent reactor power.
C. STATUS OF STRUCTURES, SYSTEMS OR COMPONENTS THAT WERE INOPERABLE AT THE START OF THE EVENT AND THAT CONTRIBUTED TO THE EVENT None.
D. NARRATIVE
SUMMARY
OF THE EVENT, INCLUDING DATES AND APPROXIMATE TIMES On 2/6/02, Modification Package 02-1003 was implemented to reduce the maximum flow on the MDAFW pumps by reducing the setpoint for the AFW flow control valves ALHV0005, 7, 9, and I1, to 142,500 Lbm/hr. During a retest, ALHVO0I I ramped up to 163,000 Lbm/hr and then began hunting +/- 10,000 Lbm/hr when flow was secured through ALHV0009, a similar valve which is supplied by a common MDAFW pump. Troubleshooting revealed a problem in the electronic flow control circuitry. By replacing a faulty electronic circuit board, ALHVOO 11 was restored to proper operation on 2/8/02.
A past operability review revealed that the ALHV0OI 1 flow control problem first occurred on 5/15/01 during ALHV0009 maintenance testing. During the test on ALHV0009, flow data was first recorded for just ALHV0009 and then the combination of ALHV0009 and ALHVOO11. When analyzed, this combined flow data revealed that ALHVOO1 1 was not controlling flow at the desired setpoint. Since ALHVOO1 1 was not being retested, the unsatisfactory flow data was not recognized. This unsatisfactory data rendered ALHVOO 11 inoperable, and thus "A" train of AFW, inoperable from 5/15/01 until 2/1/02 when Callaway Plant entered Mode 4 and the T/S 3.7.5 requirement for Auxiliary Feedwater, was no longer applicable, Although ALHVOO1 1 did not meet the T/S limit for maximum flow, the "A" train of Auxiliary Feedwater was still capable of performing its safety function. This is based on:
- 1) ALHVOO1 1 was still able to throttle flow enough to prevent pump run-out on the "A" MDAFP in the most limiting NPSH conditions.
- 2) ALHVOOI 1 was still able to throttle flow enough in the most limiting case (Feed Water Line Break on the "C" steam generator) to allow at least the minimum required flow to the "B" steam generator.
Therefore, the "A" train of the Auxiliary Feedwater system was still capable of performing its intended safety function.
NRC FORM 366A (1-2001)
NRC FORM 366AU.S. NUCLEAR REGULATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
DOCKET (2)
FACILITY NAME (1)
NUMBER (2)
LER NUMBER (6)
PAGE (3)
SEQUENTIAL I REVISION Callaway Plant Unit 1
.05000483 2002 003 00 3
OF 4
NARRATIVE (if more space is required, use additional copies of NRC Form 366A) (17)
The Tech Spec Bases for the Auxiliary Feedwater System states:
a) "The motor driven pumps supply flow to the steam generators through a normally open motor operated valve that automatically throttles flow to prevent pump run-out conditions under all steam generator pressure conditions."
b) "The AFW System design is such that it can perform its function following an FWLB between the MFW (Main Feedwater) isolation valves and containment, combined with a loss of offsite power following turbine trip, and a single active failure of one motor driven AFW pump. This results in minimum assumed flow to the intact steam generators.
One motor driven AFW pump would deliver to the broken MFW header at a flow rate throttled by the motor operated "smart" discharge valve until the problem was detected, and flow terminated by the operator. Sufficient flow would be delivered to the intact steam generators by the residual flow from the affected pump plus the turbine driven AFW (TDAFW) pump."
c) "This SR (Surveillance Requirement 3.7.5.3) verifies that AFW can be delivered to the appropriate steam generator in the event of any accident or transient that generates an ESFAS (Engineered Safety Features Actuation System), by demonstrating that each automatic valve in the flow path actuates to its correct position on an actual or simulated actuation signal. This SR includes the requirement to verify that each AFW motor-operated discharge valve, ALHV0005, 7, 9 and 11, limits the flow from the motor-driven pump to each steam generator to 300 gpm (300 gpm was 320 gpm prior to MP 02-1003)."
Calculation AL-24 evaluated the effect of dissolved nitrogen on the available NPSH for the AL pumps. Running the limiting accident scenarios on the Plant Simulator validated the results of this calculation. Case 10 in the calculation determined there was adequate Net Positive Suction Head (NPSH) available from the Condensate Storage Tank (CST) at the T/S minimum level to support running 2 MDAFW pumps at 775 gpm per pump. Other Auxiliary Feedwater pump combinations are less limiting due to the TDAFW pump causing the motor operated Auxiliary Feedwater flow control valves to close which reduces the MDAFW pump flow and required NPSH. Conservatively assuming ALHV0009 limits flow to 320 gpm, ALVOO I1 limits flow to 328 gpm and mini-flow is 120 gpm, the total flow for the "A" MDAFP would be 768 gpm. Therefore, although ALHVOO1 1 did not limit flow to the required T/S value, it was still capable of limiting flow enough to prevent a pump from operating under run-out conditions.
Accident Analysis evaluated the ability of the "A" train of Auxiliary Feedwater to perform its design function with ALHVOO1 1 unable to limit flow to 320 gpm. The FWLB was the limiting accident. Assuming the "B" MDAFW pump fails and the FWLB occurs on the "C" steam generator, ALHVOO 11 still limits flow through the break enough to provide at least the minimum assumed flow of 93.3 gpm to the "B" steam generator. Therefore, ALHVOO 11 limited Auxiliary Feedwater flow enough at 328 gpm to allow the "A" train of Auxiliary Feedwater to fulfill its Safety Analysis function.
==
Conclusion:==
Although ALHVOO1 1 did not meet the T/S limit for maximum flow, the "A" train of Auxiliary Feedwater was still capable of performing its intended safety function.
E. METHOD OF DISCOVERY OF EACH COMPONENT, SYSTEM FAILURE, OR PROCEDURAL ERROR The failure of ALHVOO1 1 to control flow at the T/S limit was discovered on 2/7/02, while performing tests associated with Callaway Modification Package 02-1003.
Subsequent review of historical data for past operability determined that ALHVOO 11 had been inoperable since 5/15/01.
NRC FORM 366A (1-2001)
NRC FORM 366AU.S. NUCLEAR REGULATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
DOCKET (2)
FACILITY NAME (1)
NUMBER (2)
LER NUMBER (6)
PAGE (3)
F SEQUENTIAL (
REVISION Callaway Plant Unit 1 YEAR I
NUMBER lNUMBER
_05000483 2002 003 00 4
OF 4
NARRATIVE (If more space is required, use additional copies of NRC Form 366A) (17)
II.
EVENT DRIVEN INFORMATION A. SAFETY SYSTEMS THAT RESPONDED Not applicable.
B. DURATION OF SAFETY SYSTEM INOPERABILITY The total duration of the time that the "A" train Auxiliary Feedwater system was inoperable was from 1259, 5/15/01 until 0426, 2/1/02 when the Callaway Plant entered Mode 4 and the Auxiliary Feedwater system was no longer required to be Operable per T/S 3.7.5. Callaway Plant was still in Mode 4 when repairs were completed on ALHVO II and the valve was declared operable. The total time of Inoperability was 260 days, 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br />, 27 minutes.
C. SAFETY CONSEQUENCES AND IMPLICATIONS OF THE EVENT.
This event did not represent a significant safety concern. Based upon an evaluation contained within this LER that details how the "A" train of Auxiliary Feedwater remained capable of satisfying its intended safety function, this event did not pose an increase in core damage frequency.
III.
CAUSE OF THE EVENT The primary cause of this event was failure of an electronic circuit board for ALHVOO 11. A contributing factor was the failure to recognize the unsatisfactory test data recorded for ALHVOO 11 on 5/15/01.
IV.
CORRECTIVE ACTIONS Corrective actions were to replace the faulty electronic circuit board for ALHVOO 11 and perform a satisfactory retest on 2/8/02. Additional corrective actions addressing the failure to recognize unsatisfactory test data are being evaluated.
V.
PREVIOUS SIMILAR EVENTS A review was conducted of LERs written within the last 3 years and there were no similar LERs. A review of Callaway Action Request System (CARS) data for the last 3 years revealed 3 CARs related to flow control problems associated with ALHV0005, 7, 9, andlor 11. They were CARs 199903183, 200103109, and 200200577.
VI.
ADDITIONAL INFORMATION The system and component codes listed below are from the IEEE Standard 805-1984 and IEEE Standard 803A-1984 respectively.
System:
BA Component: FCV NRC I-ORM 366A (1-2001)