05000280/LER-1997-009, :on 971014,declared Intake Canal Level Probes Inoperable Due to Marine Growth.Caused by Inadequate Maint of Intake Canal Level Probes.Subject Probes Were Cleaned, Tested Satisfactorily & Returned to Operable Status
| ML18153A210 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 01/13/1998 |
| From: | Christian D VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | |
| Shared Package | |
| ML18153A209 | List:
|
| References | |
| LER-97-009, LER-97-9, NUDOCS 9801210219 | |
| Download: ML18153A210 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2801997009R00 - NRC Website | |
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NRC FORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB NO. 3160-0104 (4-95)
EXPIRES 4130/98 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH lHIS MANDATORY INFORMATION COLLECTION REQUEST: 50,0 HRS.
LICENSEE EVENT REPORT (LER)
REPORTED LESSONS LEARNED ARE INCORPORATED INTO lHE LICENSING PROCESS AND FED BACK TO INDUSTRY. FORWARD COl,'M8IITS REGARDING BURDEN ESTIMATE TO lHE INFORMATION AND RECORDS MANAGEMENT BRANCH (r-e F33),
(See reverse for required number of digits/characters for each block)
U.S. t,&JCLEAR REGULATORY COl.9.11SSION, WASHINGTON. DC 20555-0001, AND TO lHE PAPERWORK REDUCTION PROJECT (3150-0104),
OFFICE OF MANAGEMENT AND
- BUDGET, WASHINGTON DC 20503.
FACILllY NAME (1)
DOCKET' NUMBER (2)
PAGE(3)
SURRY POWER STATION, Unit 1 05000-280 1 OF 5 TITLE (4)
Intake Canal Level Probes Inoperable Due to Marine Growth EVENT DATE (5}
LER NUMBER (6)
REPORT DATE (7)
OTHER FACILITIES INVOLVED 8)
SEQUENTIAL REVISION MONTH DAY YEAR FACILllY NAME DOCUMENT NUMBER MONTH DAY YEAR YEAR Surry Power Station, Unit 2 05000-281 NUMBER NUMBER 10 14 97 97
-- 009 --
01 1
98 FACILllY NAME DOCUMENT NUMBER 13 05000-OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check one or more) (11)
MODE (9)
N 20.2201(b) 20.2203(a)(2)(v)
X 50.73(a)(2)(i)
- 50. 73(a)(2)(viii)
POWER 20.2203(a)(1) 20.2203(a)(3)(i) 50.73(a)(2)(ii) 50.73(a)(2)(x)
LEVEL (10) 100 *;..
20.2203(a)(2)(i) 20.2203(a)(3)(ii) 50.73(a)(2)(iii) 73.71 20.2203(a)(2)(ii) 20.2203(a)(4) 50.73(a)(2)(iv)
OTHER 20.2203(a)(2)(iii) 50.36(c)(1) 50.73(a)(2)(v)
Specify in Abstract below
- 20. 2203( a)(2)(iv) 50.36(c)(2)
X 50.73(a)(2)(vii) or in NRC Form 366A LICENSEE CONTACT FOR THIS LER 12)
NAME I
(;~;}N;;;:;~;l;e Area Code)
D. A. Christian, Station Manager COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE TONPRDS TONPRDS SUPPLEMENTAL REPORT EXPECTED (14)
EXPECTED MONTH DAY YEAR I YES IX I NO SUBMISSION (If yes, complete EXPECTED SUBMISSION DATE).
DATE ABSTRACT (Limit.to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)
On October 14, 1997, Unit 1 was operating at 100% power with Unit 2 at Refueling Shutdown. Intake canal level instrument Channel Ill was declared inoperable at 1 O: 17 to allow testing of intake canal level probe 2-CW-LE-202. The as-found response time of 2-CW-LE-202 was greater than the acceptance limit. The probe was cleaned by divers, tested satisfactorily, and Channel Ill was returned to operable status. Channel IV was declared inoperable at 17:13 to allow canal level probe 2-CW-LE-203 to be tested. The as-found response time of 2-CW-LE-203 was also greater than the acceptance limit. The probe was cleaned by divers, tested satisfactorily, and Channel IV was returned to operable status.
Based on the conclusion that the 2-CW-LE-202 and 2-CW-LE-203 testing failures resulted from a common cause marine biofouling, Channels I and II were declared inoperable and an LCO was entered in accordance with TS 3.0.1. Intake canal level probes 1-CW-LE-102 and 1-CW-LE-103 were cleaned by divers, tested satisfactorily, and Channels I and II were returned to operable status. The TS 3.0.1 LCO was exited at 20: 10. A Category 1 RCE was performeci and determined that the failure to adequately maintain the intake canal level probes resulted in marine biofouling, which prevented the probes from achieving the required response time. This report is being 10 CFR 50.73(a)(2)(i)(B) and 10 CFR 50.73(a)(2)(vii)(D).
9801210219 980113 PDR ADOCK 05000280 S
PDR submitted pursuant to I (4-95)
U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
Surrv Power Station Unit 1 TEXT (If more space Is required, use additional copies of NRC Form 366A) (17) 1.0 DESCRIPTION OF THE EVENT DOCKET 05000- 280 LER NUMBER (6\\
PAGE (3)
YEAR I SEQUENTIAL I REVISION NUMBER NUMBER 97
- - 009 --
01 2 OF 5 On October 14, 1997, Unit 1 was operating at 100% power with Unit 2 at Refueling Shutdown (RSD), when low intake canal level instrument Channel Ill [EIIS-JE,CHA] was declared inoperable, at 10:17, to allow testing of intake canal level probe 2-CW-LE-202 [EIIS-KE,LE].
The scheduled periodic test was performed in accordance with 2-IPT-CC-CW-L-202, "Intake Canal Level Probe 2-CW-LS-202 Time Response Test and Channel Calibration." The as-found response time of 2-CW-LE-202 was greater than the acceptance limit (66 seconds). The probe was inspected and cleaned by divers, who removed some marine growth. 2-CW-LE-202 was subsequently tested satisfactorily and Channel Ill was returned to operable status at 12:26.
Recognizing that biofouling represents a potential common failure mechanism, a decision was made to promptly test intake canal level probe 2-CW-LE-203. Management also decided to declare low intake canal level instrument Channels I and II inoperable, if the results of 2-CW-LE-203 testing were unsatisfactory. As a further conservative measure, an operator was stationed at the high level intake structure [EIIS-NN] to monitor intake canal level.
Low intake canal level instrument Channel IV was declared inoperable at 17: 13 to allow 2-CW-LE-203 to be tested.
The as-found response time of 2-CW-LE-203 was also greater than the acceptance limit. The probe was inspected and cleaned by divers, who removed some marine growth. 2-CW-LE-203 was subsequently tested satisfactorily and Channel IV was returned to operable status at 17:49.
Based on the conclusion that the 2-CW-LE-202 and 2-CW-LE-203 testing failures resulted from a common cause (i.e., marine biofouling), low intake canal level instrument Channels I and II were declared inoperable at 17:26. A Limiting Condition for Operation (LCO), requiring Unit 1 to be placed in Hot Shutdown (HSD) within six hours, was entered in accordance with Technical Specification (TS) 3.0.1.
Intake canal level probes 1-CW-LE-103 and 1-CW-LE-102 were subsequently tested.
The as-found response time for both of these probes was greater than the acceptance limit. After being inspected and cleaned by divers, 1-CW-LE-103 and 1-CW-LE-102 were tested satisfactorily. Low intake canal level Channel II was returned to operable status at 19:46 and the TS 3.0.1 LCO was exited at 20: 10 when Channel I was placed in "trip." Channel I was returned to operable status on October 15, 1997, at 03:30. (4-95)
U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET LER NUMBER (6)
PAGE (3)
YEAR I SEQUENTIAL I REVISION NUMBER NUMBER Surry Power Station Unit 1 05000- 280 97
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01 3 OF 5 TEXT (If more space is required, use additional copies of NRC Form 366A) (17) 1.0 DESCRIPTION OF THE EVENT {continued)
The NRC was notified pursuant to 10 CFR 50.72(b)(2)(iii) on October 14, 1997, at 20:41.
This report is being submitted pursuant to 1 O CFR 50. 73(a)(2)(i)(B) because the inoperable canal level probes represent a condition prohibited by TS 3. 7. This report is also being submitted pursuant to 10 CFR 50. 73(a)(2)(vii)(D) since a single cause resulted in four independent channels becoming inoperable in a single system designed to mitigate the consequences of an accident.
2.0
SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS
The non-essential service water (SW) automatic isolation function [EIIS-JE,KG) ensures adequate intake canal inventory can be maintained by the emergency service water pumps [EIIS-81,P] following a design basis loss of coolant accident (LOCA) with a coincident loss of offsite power (LOOP). This function is designed to actuate when any three of the four intake canal level probes senses a canal level that is less than 23.5 feet.
To determine the potential impact of this event on the non-essential SW automatic isolation function, Engineering analyzed the results of the canal level probe testing. The analysis concluded that the as-found response time for three of the four probes, although delayed, would have been sufficient to support the design basis canal inventory requirements.
During this event, a LOCA/LOOP did not occur and the intake canal level remained above 23.5 feet. As a conservative measure, an operator was stationed at the high level intake structure, following the testing of Channel Ill, to monitor intake canal level.
In summary, this event resulted in no safety consequences or significant implications and the health and safety of the public were not affected at any time.
3.0
CAUSE
A Category 1 Root Cause Evaluation (RCE) was performed and determined that the event was caused by inadequate maintenance of the intake canal level probes. The failure to adequately clean the intake canal level probes/activate the antifoulant coating resulted in marine biofouling, which prevented the probes from achieving the required response time. Activation of the antifoulant coating is accomplished by lightly abrading the coating to expose a fresh surface of copper, which facilitates the coating's resistance to marine growth.
rrr================I (4-95)
U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
Sunv Power Station Unit 1 TEXT (If more space is required, use additional copies of NRC Form 366A) (17) 3.0 DOCKET 05000- 280 LER NUMBER (6)
PAGE (3)
YEAR I SEQUENTIAL I REVISION NUMBER NUMBER 97
- - 009 --
01 40F 5
. A factor in the inadequate maintenance of the probes was the failure to inspect/clean the probes as frequently as the coating manufacturer recommended.
An increased inspection/cleaning frequency was not considered when the coating was changed from Teflon to the current Epco-Tek 2000 coating, since this coating is superior to the Teflon coating.
4.0 IMMEDIATE CORRECTIVE ACTION(S)
Following initial testing, 2-CW-LE-202 was inspected and cleaned by divers. The probe was subsequently tested satisfactorily and instrument Channel Ill was returned to operable status at 12:26.
A Deviation Report was submitted to document the deviating condition and to initiate
corrective actions
As a conservative measure, an operator was stationed at the high level intake structure at 14:45 to monitor intake canal level until the intake canal level instrument channels could be verified to satisfy TS requirements.
Following initial testing, 2-CW-LE-203 was inspected and cleaned by divers. The probe was subsequently tested satisfactorily and instrument Channel IV was returned to operable status at 17:49.
Based on the conclusion that the 2-CW-LE-202 and 2-CW-LE-203 testing failures resulted from a common cause (i.e., marine biofouling), low intake canal level Channels I and II were declared inoperable at 17:26. An LCO, requiring Unit 1 to be placed in HSD within six hours, was entered in accordance with TS 3.0.1; 1-CW-LE-103 and 1-CW-LE-102 were cleaned by divers and subsequently tested satisfactorily. Low intake canal level Channel II was returned to operable status at 19:46 and the TS 3.0.1 LCO was exited at 20: 1 O when Channel I was placed in "trip." Channel I was returned to operable status on October 15, 1997, at 03:30.
5.0
ADDITIONAL CORRECTIVE ACTIONS
An interdepartmental RCE Team investigation was initiated by station management to 1
determine the causes of this event and to recommend corrective actions to prevent recurrence of a similar event.
"r.==-===========! (4-95)
U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET LER NUMBER (6)
YEAR I SEQUENTIAL I REVISION NUMBER NUMBER Surry Power Station Unit 1 05000 - 280 97
--009 --
01 TEXT (If more space is required, use additional copies of NRC Form 366A) (17) 5.0 PAGE(3)
SOF 5 Associated with the RCE efforts, in the November/December 1997 time frame, 1-CW-LE-102 and 2-CW-LE-202 were replaced with new probes with activated antifoulant coating. Additionally, 1-CW-LE-103 and 2-CW-LE-203 were inspected and cleaned using current recommendations from the coating manufacturer, and the antifoulant coating on the probes was activated.
6.0 ACTIONS TO PREVENT RECURRENCE Actions will be implemented to ensure proper cleaning of the probes and activation of the antifoulant coating. In addition, the appropriate frequency of inspection and cleaning of the probes will be determined.
The process for and effectiveness of incorporating vendor or manufacturer recommendations into appropriate documentation will be reviewed.
7.0
SIMILAR EVENTS
LER 50-280/50-281/95-006-00, "Emergency Service Water Pumps 1-SW-P-1A and 1-SW-P-1 C Inoperable Due to Marine Growth" 8.0
ADDITIONAL INFORMATION
The top coat of the coating system is the antifoulant copper-based epoxy Epco-Tek 2000 I manufactured by Hi-Tek Chemical Company.