05000528/LER-2005-003, Regarding Calibration Method That Might Have Failed to Provide Reactor Protection During Low Power Operation
| ML051520471 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 05/20/2005 |
| From: | Danni Smith Arizona Public Service Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 102-05273-DMS/CKS/DJS LER 05-003-00 | |
| Download: ML051520471 (10) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(vii)(A), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 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 |
| 5282005003R00 - NRC Website | |
text
e v-1 OCFR50.73 A subsidiary of Pinnacle West Capital Corporation Palo Verde Nuclear Generating Station David M. Smith Tel: 623-393-6116 Mail Station 7602 Plant Manager Fax: 623-393-6077 PO Box 52034 Nuclear Production e-mail: DSMITH10@apsccom Phoenix. Arzona 85072-2034 102-05273-DMS/CKS/DJS May 20, 2005 ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001
Dear Sirs:
Subject:
Palo Verde Nuclear Generating Station (PVNGS)
Units 1, 2, and 3 Docket No. STN 50-528, 50-529, and 50-530 License No. NPF 41, NPF 51 and NPF 74 Licensee Event Report 2005-003-00 Attached please find Licensee Event Report (LER) 50-528/2005-003-00 prepared and submitted pursuant to 10 CFR 50.73. This LER reports a condition that could have prevented the fulfillment of a safety function at some future point in time, if a revision to a calibration procedure was not implemented.
In accordance with 10 CFR 50.4, a copy of this LER is being forwarded to the NRC Region IV Office and the Senior Resident Inspector. If you have questions regarding this submittal, please contact Daniel G. Marks, Section Leader, Regulatory Affairs, at (623) 393-6492.
Arizona Public Service Company makes no commitments in this letter.
Sincerely, DMS/CKS/DJS/ca A member of the STAP.S (Strategic Teaming and Resource Sharing) Alliance Callaway
- Comanche Peak
- Diablo Canyon
- Palo Verde
- South Texas Project
- Wolf Creek
ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Licensee Event Report 50-528/2005-003-00 Page 2 Attachment cc:
B. S. Mallet M. B. Fields G. G. Warnick NRC Region IV Administrator NRC NRR Project Manager for PVNGS NRC Senior Resident Inspector for PVNGS (all w/attachment)
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/3012007 (6-2004)
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, the NRC may for each block) not conduct or sponsor, and a person Is not required to respond to, the digits/characters frecblk)Information collection.
- 3. PAGE Palo Verde Nuclear Generating Station (PVNGS) Unit 1 05000528 1 OF 8
- 4. TITLE Calibration method that might have failed to provide reactor protection during low power operation.
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED I
l FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER LREOV MONTH DAY YEAR PVNGS Unit 2 05000529 FACILITY NAME DOCKET NUMBER 03 24 2005 2005 - 003 -
00 05 20 2005 PVNGS Unit 3 05000530
- 9. OPERATING MODE II.THIS REPORTIS SUBMITTED PURSUANTTOTHE REQUIREMENTS OF 10 CFR§: (Checkal/thatapply) o 20.2201(b) 0 20.2203(a)(3Xi)
[I 50.73(aX2)(i)(C)
E 50.73(aX2)(vii) 1El 20.2201(d)
[I 20.2203(a)(3Xii)
El 50.73(aX2)(ii)(A)
El 50.73(a)(2)(vii)(A) o 20.2203(a)(1) 0 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
E 50.73(aX2)(viii)(B) o 20.2203(a)(2)(i) 0 50.36(cX1XiXA) 0 50.73(a)(2)(iii) a 50.73(aX2)(ix)(A)
- 10. POWER LEVEL 0 20.2203(a)(2)(ii) 0 50.36(cX1)(il)(A)
El 50.73(a)(2)(iv)(A) 03 50.73(a)(2)(x) o 20.2203(a)(2)(Iii) 0 50.36(cX2)
ED 50.73(a)(2)(v)(A) 0 73.71(aX4) o 20.2203(a)(2)(lv) 0 50.46(a)(3Xii) 0 50.73(a)(2)(v)(B)
El 73.71(a)(5) 100 C 20.2203(a)(2)(v) 0 50.73(a)(2XiXA) 0 50.73(a)(2)(v)(C) 0 OTHER El 20.2203(a)(2)(vi) 0 50.73(a)(2XIXB) 0 50.73(a)(2)(v)(D)
Specify In Abstract below or In (if more space is required, use additional copies of (If more space is required, use additional copies of (It more space is required, use additional copies of NRC Formn 366A)
There were no failures of components with multiple functions involved in this event.
- 4.
CHRONOLOGY OF RELEVANT EVENTS:
On December 8, 2004 a valid question was raised concerning the Safety Log Channels.
As reported in Condition Reports/Disposition Request (CRDR) # 2760452:
- On December 9, 2004 at 08:44, the CRDR notes that a discussion was held on 12/08/2004 to try and determine the validity of this concern. Representatives from the Shift Technical Advisor group, I&C Design Engineering, Transient Analysis, l&C Maintenance, and l&C Maintenance Engineering, tentatively came to the conclusion that there is evidence to support the conclusion that at low power, there is additional uncertainties that may challenge the ability of the Hi LOG POWER TRIP, LOG 1 and LOG 2 bistables to perform their intended safety function.
- On December 9, 2004 at 09:00, the CRDR notes that the STA representative recommended that this CRDR be marked for Control Room review, and the impact on Operations would be determined at that time.
The condition is fundamentally a concern about the instrument channels, whether they are linear over their entire span. The condition is primarily related to the behavior of the cards in the channel drawer, not including the detector and the preamplifier. The channels are calibrated at essentially full power, which is in the Mean Square Voltage (MSV) region.
However, the safety function is of concern at low powers in the Log Count Rate (LCR) region. The concern was that the LCR and MSV regions did not adequately align so that the channels would be unacceptably inaccurate at low powers. This appeared to be caused by the calibration method provided by the vendor and implemented by Palo Verde which introduced "tolerance creep" that might have failed to provide reactor protection during very low power operation.
An Engineering evaluation (CRDR) was initiated to address these concerns. On March 25, 2005 the outcome of the Engineering study showed adjustments were need to continue to provide reactor protection during very low power operation. The corrective actions listed in section 8 below summarize what APS is doing to ensure that there is no loss of this safety function.
(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 Form 366A)
- 9.
PREVIOUS SIMILAR EVENTS
There have been no previous similar events in the past three years that had a similar failure mechanism or that should have prevented this event from previously implemented
corrective actions