ML18152B608

LER 98-010-01:on 980715,intake Canal Level Probes Were Inoperable Due to Marine Growth.Caused by Design of Canal Level Instrumentation.Canal Level Probes Will Continue to Be Monitored More Closely

ML18152B608
Person / Time
Site:	Surry
Issue date:	10/23/1998
From:	Grecheck E VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML18152B609	List: ML18152B608 ML18152B698
References
LER-98-010, LER-98-10, NUDOCS 9810300345
Download: ML18152B608 (5)

Text

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION e

APPROVED BY 0MB NO. 3150-0104 EXPIRES 06/30/2001 (6-1998) Estimated burden per response to comply with this mandatory information collection request: 50 hrs. Reported lessons learned are incorporated into the LICENSEE EVENT REPORT (LER) licensing process and fed bad< to industry. Forward com menlll regarding burden estimate to the Records Management Branch (T-6 F33), U.S. Nudear Regulatory Commission, Washington, DC 20555-0001, and to the Pape!WOfk (See reverse for required number of Reduction Project (3150-0104 ), Olli ce of Management and Budget, digits/characters for each block) Washington, DC 20503. If an infonnation collection does not display a currently valid 0MB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the infonnation collection.

FACILITY NAME 111 DOCKET NUMBER 121 PAGE(3l 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)

MONTH DAY YEAR YEAR ISEQUENTIAL NUMBER REVISION NUMBER MONTH DAY YEAR FACILITY NAME Surrv Unit 2 DOCKET NUMBER 05000-281 FACILITY NAME DOCKET NUMBER 07 15 1998 1998 - 010 - 01 10 23 1998 05000 THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check one or morel 111)

OPERATING MODE (91 N 20.2201(b) 20.2203(a){2)(vl X 50. 73(all2lm 50.73(a)(2)(viii) 20.2203(a){1 l 20.2203(a){3)(i) 50. 73(a)(2)(ii) 50. 73(al(2){x)

POWER LEVEL 110) 100% 20.2203lall2Uil 20.2203lal{3lliil 50. 73lall2lliiil 73.71

., . ,* " .- 20.2203(a)(2)(ii) 20.2203(a)(4l 50. 73lall2>livl OTHER

- *.* 20.2203(a){2){iii) 50.36lc)(1) 50. 73(a)(2)(v)

Specify in Abs!ract below or

.*.* 20.2203Ca){2){ivl 50.38/c){2l X 50. 73(al{2l(vii) in NRC Form 366A LICENSEE CONTACT FOR THIS LER f12l NAME "TELEPHONE NUMBER (Include Al8e Code)

E. S. Grecheck, Site Vice President (757) 365-2000 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 13)

REPORTABLE REPORTABLE CAUSE SYSTEM COW'ONENT MANUFACTURER TO EPIX CAUSE SYSTEM COMPONENT MANUFACTURER TO EPIX SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED MONTH DAY YEAR jves (If vas, complete EXPECTED SUBMISSION. DATE). Ix NO SUBMISSION DATE (15)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typelNritten lines) (16)

On July 15, 1998, with Units 1 and 2 operating at 100% po'Ner, low intake canal level instrument Channel I was declared inoperable at 10:27 to allow testing of intake canal level probe 1-CW-LE-102. The as-found response time of 1-CW-LE-102 was unsatisfactory. Similar marine fouling had been observed the previous day on intake canal level probe 2-CW-LE-203. Recognizing that biofouling represents a potential common failure mechanism, 2-CW-LE-203 and the associated low intake canal level instrument Channel IV were conservatively declared inoperable at 10:50. With Channels I and IV both inoperable, an action statement was entered in accordance with Technical Specification {TS) 3.0._1. 1-CW-LE-102 was cleaned by a diver, tested satisfactorily, and Channel I was returned to operable status. The TS 3.0.1 action statement was exited at 11 :28. 2-CW-LE-203 was tested at 14:23. The as-found response time was unsatisfactory. 2-CW-LE-203 was cleaned by a diver, tested satisfactorily, and Channel IV was returned to operable status at 16:38. The condition of the other two intake canal level probes was evaluated and determined to be acceptable. A Root Cause Evaluation concluded that the design of the canal level instrumentation is not optimal for low maintenance operation in a marine environment and that the rate of biofouling is unpredictable. Based on these conclusions, the canal level probes will continue to be monitored more closely and the feasibility of using other types of level sensing equipment will be evaluated. This report is being submitted pursuant to 10 CFR 50.73{a)(2)(i)(B) and 10 CFR 50.73(a)(2)(vii)(D) .

9810300345 981023 PDR ADOCK 05000280 S PDR

e e NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6-1998)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) DOCKET (2) LER NUMBER 16) PAGE (3)

SURRY POWER STATION, Unit 1 YEAR ISEQUENTIAL NUMBER REVISION NUMBER 05000 - 280 1998 - 010 - 01 2 OF 5 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

1.0 DESCRIPTION

OF THE EVENT On July 15, 1998, with Units 1 and 2 operating at 100% power, low intake canal level instrument Channel I [EIIS-JE,CHA] was declared inoperable at 10:27 to allow testing of intake canal level probe 1-CW-LE-102 [EIIS-KE,LE] .. In accordance with Technical Specification (TS) Table 3.7-2, Operator Action No. 20 was entered requiring Channel I to be returned to service or placed in trip within six hours. The scheduled periodic test was performed in accordance with 1-IPT-CC-CW-L-102, "Intake Canal Level Probe 1-CW-Ls-*102 Time Response Test and Channel Calibration." The results of the test were unsatisfactory with the as-found response time of 1-CW-LE-102 exceeding the acceptance limit (60 seconds).

Although to a lesser extent, similar marine fouling had been observed the previous day on intake canal level probe 2-CW-LE-203. Recognizing that biofouling represents a potential common failure mechanism, 2-CW-LE-203 and the associated low intake canal level instrument Channel IV were conservatively declared inoperable at 10:50. In accordance with TS Table 3.7-2, Operator Action No. 20 was entered for Channel IV.

With Channels I and, IV both inoperable, an action statement was entered in accordance with TS 3.0.1, requiring both units to be placed in Hot Shutdown (HSD) within six hours.

1-CW-LE-102 was inspected and cleaned by a diver, who removed some marine growth.

The probe was subsequently tested satisfactorily and Channel I was returned to operable status. The TS 3.0.1 action statement and the TS 3. 7-2 action statement for Channel I were exited at 11 :28.

2-CW-LE-203 was tested in accordance with 2-IPT-CC-CW-L-203 at 14:23. The results of the test were unsatisfactory with the as-found response time exceeding the acceptance limit. 2-CW-LE-203 was inspected and cleaned by a diver and subsequently tested satisfactorily. While the condition of 2-CW-LE-203 was further evaluated by Engineering, Channel IV was placed in the tripped condition at 15:00 and the associated TS 3.7-2 action statement was exited.

Engineering later concluded that the condition of 2-CW-LE-203 was acceptable. At 15:27, Channel IV was restored and TS Table 3.7-2, Operator Action No. 20 was entered to facilitate additional testing of 2-CW-LE-203. The probe was tested satisfactorily and Channel IV was returned to operable status. The TS 3.7-2 action statement for Channel IV was exited at 16:38.

The condition of the other two intake canal level probes, 1-CW-LE-103 and 2-CW-LE-202, was evaluated. The evaluation concluded that 2-CW-LE-202 did not need to be tested since it had been cleaned and tested satisfactorily on July 11, 1998.

The condition of 1-CW-LE-103 was also determined to be acceptable based on a visual inspection performed on July 14, 1998.

NRC FORM 366A(6-1998)

e e NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6-1998)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) DOCKET (2)

YEAR I SEQUENTIAL NUMBER I

LER NUMBER (6)

REVISION NUMBER PAGE (3)

SURRY POWER STATION, Unit 1 05000 -280 1998 - 010 - 01 3 OF 5 TEXT (ff more space is required, use additional copies of NRC Form 366A) (17)

1.0 DESCRIPTION

OF THE EVENT (Continued)

The NRC was notified pursuantto 10 CFR 50.72(b)(2)(iii)(D) on July 15, 1998, at 17:21.

This report is being submitted pursuant to 10 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 two 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 the two degraded probes, although delayed, would have been sufficient to support the design basis canal inventory requirements.

The intake canal level is also monitored by an independent system that provides level indication and high/low level alarms in the main control room. In the event of a low canal level condition, station procedures direct corrective/mitigative actions, including isolation of non-essential SW.

During this event, a LOCA/LOOP did not occur and the intake canal level remained above 23.5 feet. 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.

NRC FORM 366A(6-1998)

• . ~*-*-* - -*;* .,..._ *eo-- *-*~ .

e e NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6-1998)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION a!°ACILITY NAME 111 DOCKET (2) LER NUMBER 6) PAGE 131 SURRY POWER STATION , Unit 1 YEAR I SEQUENTIAL NUMBER REVISION NUMBER 05000 -280 1998 - 010 - 01 4 OF 5 TEXT (If more space is required, use additional copies ofNRC Form 366A) (17) 3.0 CAUSE A Category 1 Root Cause Evaluation (RCE) was performed to determine the causes of this event and to recommend corrective actions. The RCE concluded that: 1) the design of the canal level instrumentation is not optimal for low maintenance operation in a marine environment and, 2) the rate of marine biofouling is unpredictable as a result of the continually changing environmental conditions of the intake canal.

4.0 IMMEDIATE CORRECTIVE ACTION(S)

Following the unsatisfactory testing of 1-CW-LE-102 on July 15, 1998, 2-CW-LE-203 and the associated low intake canal level instrument Channel IV were conservatively declared inoperable. With Channels I and IV inoperable, an action statement was entered at 10:50 in accordance with TS 3.0.1.

1-CW-LE-102 was inspected and cleaned by a diver and was subsequently tested satisfactorily. Channel I was returned to operable status and the TS 3.0.1 act_ion

• statement was exited at 11 :28.

2-CW-LE-203 was tested at 14:23. The results of the test were unsatisfactory with the as-found response time exceeding the acceptance limit. 2-CW-LE-203 was inspected and cleaned by a diver and subsequently tested satisfactorily. Channel IV was returned to operable status at 16:38.

A Deviation Report was submitted to document the deviating condition and to initiate corrective actions.

The condition of the other two intake canal level probes, 1-CW-LE-103 and 2-CW-LE-202, was evaluated. The evaluation concluded that the condition of these two probes was acceptable.

5.0 ADDITIONAL CORRECTIVE ACTIONS The operability of 1-CW-LE-103 was confirmed by testing on July 15, 1998, at 17:48.

An interdepartmental RCE Team investigation was initiated by station management to determine the causes of this event.

NRC FORM 366A (6-1998)

i,I.

e e NRC FORM 388A U.S. NUCLEAR REGULATORY COMMISSION

' (6-1998)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION

~ACILITY NAME (11 DOCKET (2) LER NUMBER 81 PAGE (3)

SURRY POWER STATION , Unit 1 YEAR I SEQUENTIAL NUMBER REVISION NU~ER 05000 -280 1998 - 010 - 01 5 OF 5 TEXT (ff mom space is required, use additional copies of NRC Fo"'! 366A) (17) 6.0 ACTIONS TO PREVENT RECURRENCE Other types of level sensing equipment, which does not need to physically contact the intake canal water, will be evaluated to determine whether such equipment would be reliable in this application and could be qualified as safety-:related.

As another option, Engineering will evaluate the feasibility of applying a different coating on the canal level probes which contains a more potent biocide.

Until a viable option is implemented, the intake canal level probes will continue to be monitored more closely and cleaned more frequently during seasonal periods that are conducive to rapid marine biofouling.

7.0 SIMILAR EVENTS LER 50-280/50-281/97-009-00, "Intake Canal Level Probes Inoperable Due to Marine Growth" LER 50-280/50-281/95-006-00, "Emergency Service Water Pumps 1-SW-P-1A and 1-SW-P-1C Inoperable Due to Marine Growth" NRC FORM 366A (6-1998)