05000305/LER-2006-006, Re Safety Injection Accumulator Level to Volume Correlation and Alarm Setpoints Non-Conservative
| ML062570178 | |
| Person / Time | |
|---|---|
| Site: | Kewaunee  |
| Issue date: | 09/07/2006 |
| From: | Hartz L Dominion, Dominion Energy Kewaunee |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 06-739 LER 06-006-00 | |
| Download: ML062570178 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 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 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(B) |
| 3052006006R00 - NRC Website | |
text
Dominion Dominion Energy Kewaunee, Inc.
N490 Highway 42, Kewaunee, WI 54216-9511 SEP 0 7 2006 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Serial No.06-739 KPS/LIC/RS: RO Docket No.
50-305 License No. DPR-43 DOMINION ENERGY KEWAUNEE. INC.
KEWAUNEE POWER STATION LICENSEE EVENT REPORT 2006-006-00
Dear Sirs:
Pursuant to 10 CFR 50.73, Dominion Energy Kewaunee, Inc., hereby submits the following Licensee Event Report applicable to Kewaunee Power Station.
Report No. 50-305/2006-006-00 This report has been reviewed by the Plant Operating Review Committee and will be forwarded to the Management Safety Review Committee for its review.
If you have any further questions, please contact Mr. Richard Repshas at (920) 388-8217.
Very truly yours, Leslie N. Hart Site Vice President, Kewaunee Power Station Attachment Commitments made by this letter: NONE
Serial No.06-739 Page 2 of 2 cc:
Regional Administrator, Region III U.S. Nuclear Regulatory Commission 2443 Warrenville Road Suite 210 Lisle, IL 60532-4352 Mr. D. H. Jaffe Project Manager U.S. Nuclear Regulatory Commission Mail Stop 0-7-D-1 Washington, D. C. 20555 NRC Senior Resident Inspector Kewaunee Power Station
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LICENSEE EVENT REPORT (LER)
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FACILITY NAME (1)
DOCKET NUMBER (2)
PAGE (3)
Kewaunee Power Station 05000305 1 of 3
TITLE (4)
Safety Injection accumulator level to volume correlation and alarm setpolnts non-conservative EVENT DATE (5)
LER NUMBER (6)
REPORT DATE (7)
OTHER FACILITIES INVOLVED (8)
T REV FACILITY NAME DOCKET NUMBER MO DAY YEAR YEAR NUMBER I NO MO DAY YEAR 07 13 2006 2006 -
006 -
00 09 07 2006 FACILITY NAME DOCKETNUMBER OPERATING N
THIS REPORT IS SUBMI'TED PURSUANT TO THE REQUIREMENTS OF 10 CFR.: (Check all that apply) (11)
MODE (9) 20.2201(b) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(B) 50.73(a)(2)(ix)(A)
POWER 20.2201 (d) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(x)
LEVEL (10) 100 20.2203(a)(1) 50.36(c)(1)()(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) 20.2203(a)(2)(ii) 50.36(c)(2) 50.73(a)(2)(v)(B)
OTHER 20.2203(a)(2)(liU) 50.46(a)(3)(ii) 50.73(a)(2)(v)(C)
Specify in Abstract below or in 20.2203(a)(2)(iv) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(D) 20.2203(a)(2)(v)
X 50.73(a)(2)(i)(B) 50.73(a)(2)(vii) 20.2203(a)(2)(vi) 50.73(a)(2)(i)(C) 50.73(a)(2)(viii)(A)
S 20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(B)
UCENSEE CONTACT FOR THIS LER (12)
NAME TELEPHONE NUMBER (Include Area Code)
Richard Sattler (920) 388-8121 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
MANU-REPORTABLE MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT FACTURER TO EPIX
CAUSE
SYSTEM COMPONENT FA CTURER TO EPIX SUPPLEMENTAL REPORT EXPECTED (14)
EXPECTED MONTH DAY YEAR YES (If yes, complete EXPECTED SUBMISSION DATE).
X NO DATE (15)
ABSTRACT On July 13, 2006, with the plant at 100 percent power, non-conservative values were identified for the safety injection accumulator levels due to incorrect volume to level correlations and incorrect level alarm setpoints.
Questions had been raised on how to determine the proper indicated safety injection accumulator level to ensure compliance with the Technical Specification requirement of 1225 to 1275 cubic feet for each accumulator. Accumulator level is indicated from instrumentation in percent level. Two operator aids provide a correlation graph of cubic feet versus percent indicated level. Per the operator aids, the low level limit in accumulator A was 25% and the high level limit was 50%. The low level limit in accumulator B was 22% and the high level limit was 50%. Additionally, there are low and high accumulator level alarms at 26% and 50%
respectively. If either alarm value was reached, level was established between 38% and 40%. Analysis currently shows that minimum required level to meet the Technical Specification is 39% for accumulator A and 42% for accumulator B and that the maximum required level is 60% for accumulator A and 62% for accumulator B. A new normal operating range has been established between 46% and 48% accumulator level.
The causes of this event are; a 1978 set point methodology not taking into account instrument loop accuracy tolerances, and failure to update the operator aids and level alarm setpoints after an issue was identified in 1991 (calibration of the accumulator level instruments inaccurate due to not being properly pressure compensated for Nitrogen cover gas).
This is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B), "Any operation or condition which was Prohibited bv the plant's Technical Specifications." There was no safety system functional failure.U.S. NUCLEAR REGULATORY COMMISSION (1-2001 )
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
Kewune Poer taton 500305 YEAR IISEQUENTIAL IREVISION Kewune owr taton050005NUMBER NUMBER 2 of 3 12006
-- 006 00 TEXT (if mnore space Is required, use addtional copes of NRC FormW36,) (17)
Event Description
On July 13, 2006, with the plant at 100 percent power, non-conservative values were identified for the safety injection accumulator [ACC] levels. The non-conservatism was caused by incorrect volume to level correlations and resulted in incorrect level alarm [LA] setpoints. Questions had been raised on how to determine the proper indicated safety injection accumulator level to ensure compliance with the Technical Specification requirement of 1225 to 1275 cubic feet volume for each accumulator. Accumulator level is indicated from instrumentation in percent level. Two operator aids provide a correlation graph of cubic feet versus percent level. The operator aids identified the low level limit in accumulator A as 25% and the high level limit as 50%. The low level limit in accumulator B was identified as 22% and the high level limit as 50%.
Additionally, there were low and high accumulator level alarms at 26% and 50% respectively. Acceptance criteria per the surveillance procedure for meeting the Technical Specification was between 26% and 50%. If either alarm was reached, level was established between 38% and 40%.
Recent calculations show the minimum required level to meet the Technical Specification is 39% for accumulator A and 42% for accumulator B. The maximum required level to meet the Technical Specification is 60% for accumulator A and 62% for accumulator B. A new normal operating range has been established between 46% and 48% accumulator level.
Operator aids for accumulator level were not correct based on 1978 set point determination. They were also not updated when the accumulator level calibration was reevaluated in 1991 for not being properly pressure compensated or when a volumetric test was performed in 1992.
With the new calculated safety injection accumulator levels, there would have been numerous times in the past where accumulator level would have been below the required Technical Specification volume limit of 1225 cubic feet when the accumulators were required to be operable. In the surveillance procedure for "Shift Instrument Channel Checks-Operating," the acceptance criteria for accumulator low level were "no alarm annunciated" and "level greater than or equal to 26%." Additionally, the operator aids showed 1225 cubic feet corresponding to an indicated level of 25% for accumulator A and 22% for accumulator B. This would have been below the newly calculated minimum required levels.
Event Analysis
This is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B), "Any operation or condition which was prohibited by the plant's Technical Specifications."
The SI accumulators actuate during the following transients and accidents: LOCA, main steamline break with offsite power available, main steamline break without offsite power, and feedwater malfunction at hot zero power. At a minimum level corresponding to the existing low level alarm, the volumetric shortfall below Technical Specification requirements would have been 27.2 cu. ft (2.2% of 1225 cu. ft.). Evaluation of the Kewaunee safety analyses has concluded that the accumulators would continue to satisfy the safety analysis acceptance criteria at this minimum level. Therefore, there was no safety significance associated with this event.U.S. NUCLEAR REGULATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET NUMBER (2 LER NUMBER (6)
PAGE (3)
YEA SEQUENTIAL IREVISION Kewaunee Power Station 05000305 Y
NUMBER NUMBER 3 of 3 1
I 2006 006 00 TEXT (if more space is required, use additional copies of NRC Form 36WA) (17)
There is no safety system functional failure associated with this event since the condition would not have prevented fulfillment of the safety function of the system.
Cause
The causes of this event were:
- 1. A 1978 set point methodology not taking into account test equipment and instrument loop accuracy tolerances.
- 2. Failure to update the operator aids and level alarm setpoints after a similar issue was identified in 1991 (calibration of the accumulator level instruments inaccurate due to not being properly pressure compensated - LER 91-009).
Corrective Actions
- 1. An analysis was performed to determine conservative limits (in percent) to maintain the level between the Technical Specification required volumes. Proper accumulator levels were established.
- 2. Interim actions were established to monitor accumulator levels hourly until the level alarm setpoints are revised.
- 3. The station setpoint program was verified to require addressing all potential setpoint error contributors.
- 4. Technical Specifications will be reviewed to identify any setpoints with potential translation errors between the requirement and the indication. The calculations for these set points will be re-verified.
- 5. Controls for the use of operator aids are being enhanced. Existing operator aids will be reviewed and dispositioned into the correct process (operator aid, procedure, or drawing).
Similar Events
LER 91-009-00, Error in Safety Injection accumulator level indication caused by not compensating for effects of nitrogen density during calibration.