05000280/LER-1995-010, :on 951006,four Component Cooling Heat Exchangers Determined to Be Inoperable.Caused by Tubesheet Blockage by Hydroids.Component Cooling Heat Exchangers Removed from Svc & Cleaned

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:on 951006,four Component Cooling Heat Exchangers Determined to Be Inoperable.Caused by Tubesheet Blockage by Hydroids.Component Cooling Heat Exchangers Removed from Svc & Cleaned
ML18153A657
Person / Time
Site: Surry Dominion icon.png
Issue date: 11/01/1995
From: Christian D
VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML18153A656 List:
References
LER-95-010, LER-95-10, NUDOCS 9511080354
Download: ML18153A657 (6)
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LER-1995-010, on 951006,four Component Cooling Heat Exchangers Determined to Be Inoperable.Caused by Tubesheet Blockage by Hydroids.Component Cooling Heat Exchangers Removed from Svc & Cleaned
Event date:
Report date:
Reporting criterion: 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)
10 CFR 50.73(a)(2)(viii)(B)
10 CFR 50.73(a)(2)(iii)
10 CFR 50.73(a)(2)(x)
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
2801995010R00 - NRC Website
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text

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NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB NO. 3150-0104 (5-92)

EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD LICENSING EVENT REPORT (LER)

COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO (See reverse for required number of digits/characters for each block)

THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BUDGET. WASHINGTON, DC 20503.

FACILITY NAME (1)

DOCKET NUMBER (2)

I II PAGE (3)

SURRY POWER STATION, Unit 1 05000 - 280 1 OF 6 TITLE (4)

Four Inoperable Component Cooling Heat Exchangers Due to Macrofouling EVENT DATE 5)

LEA NUMBER (6 REPORT DATE (7)

OTHER FACILITIES INVOLVED 8)

MONTH DAY YEAR YEAR SEQUENTIAL REVISION MONTH DAY YEAR FACILITY NAME DOCKET NUMBER NUMBER NUMBER Surry Unit 2 05000 - 281 10 06 95 95

-- 010 --

00 11 01 95 FACILITY NAME DOCKET NUMBER 05000 -

OPERATING THIS REPORT IS SUBMITIED PURSUANT TO THE REQUIREMENTS OF 10 CFR:(Check one or more) (11)

MODE (9)

N 20.402(b) 20.405(c) 50.73(a)(2)(iv) 73.71(c)

POWER 20.405(a)(1 )(i) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c)

LEVEL (10) 100 %

20.405(a)(1 )(ii) 50.36(c)(2)

X 50.73(a)(2)(vii)

OTHER 20.405(a)(1 )(iii)

X 50.73(a)(2)(i)

50. 73( a)(2)(viii)(A)

(Specify in Abstract below and 20.405(a)(1 )(iv)

50. 73( a)(2)(ii) 50.73(a)(2)(viii)(B) in Text, NRG Form 366A) 20.405(a)(1 )(v) 50.73(a)(2)(iii) 50.73(a)(2)(x)

LICENSEE CONTACT FOR THIS LEA 12)

NAME I (804r35u7~31(184ding Area Code)

D. A. Christian, Station Manaqer COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13

CAUSE

SYSTEM COMPONENT MANUFACTURER ae~ITT=e rB

CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTABLE TONPRDS TONPRDS X

cc HX Y030 y

SUPPLEMENTAL REPORT EXPECTED (14l I

EXPECTED I MONTH I DAY I !_ES lete EXPECTED SUBMISSION DATE\\

X I NO I

SUBMISSION DATE (15)

I I

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

On October 6, 1995, at 2250 hours0.026 days <br />0.625 hours <br />0.00372 weeks <br />8.56125e-4 months <br />, Unit 1 was at cold shutdown and Unit 2 was operating at 100% when the four Component Cooling Heat Exchangers (CCHX) were determined to be inoperable due to tubesheet macrofouling. One heat exchanger was cleaned and returned to service at 0055 on October 7, 1995, and a second heat exchanger was returned to service at 0544 on October 7, 1995, meeting Technical Specification requirements for one Unit operation.

A Root Cause Evaluation determined that the CCHXs were rendered inoperable due to SW tubesheet blockage caused by hydroids and other marine material breaking off from the High Level Intake Structure B and the B 96 inch CW line when the 96 inch line was returned to service following maintenance on October 6, 1995. Engineering analysis determined that actual heat removal capacity of the four CCHXs was adequate for the required heat loads, therefore, there were no safety consequences or implications due to this event.

is being reported pursuant to 1 OCFR50.73(a)(2)(i)(B) and 1 OCFR50.73(a)(2)(vii).

NRG FORM 366 (5-92) 9511080354 951101 PDR ADOCK 05000280 S

PDR This event I YEAR I

NRC FORM366 (5-92)

U.S. NUCLEAR REGULATORY COMMISSION LICENSING EVENT REPORT (LER}

(See reverse for required number of digits/characters for each block)

FACILITY NAME (1)

DOCKET NUMBER 12)

SURRY POWER STATION, Unit 1 05000- 280 TEXT (If more space is required, use additional copies of NRG Form 366A) (17) 1.0 DESCRIPTION OF THE EVENT APPROVED BY 0MB NO. 3150-0104 EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714). U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON. DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104). OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

LER NUMBER 16l PAGE(3)

YEAR SEQUENTIAL NUMBER REVISION NUMBER 95

- 010 -

00 2oF6 Following trash rack maintenance, the Unit 1 High Level Intake Structure B (HUS) [EIIS-NN] was returned to service on October 3, 1995. On October 6, 1995, at 1151 hours0.0133 days <br />0.32 hours <br />0.0019 weeks <br />4.379555e-4 months <br />, the 42 inch Component Cooling [EIIS-CC] Heat Exchanger (CCHX) [EIIS-HX] Service

  • Water (SW) supply was swapped from the HUS D to its alternate source from the HUS B.

At 1532 hours0.0177 days <br />0.426 hours <br />0.00253 weeks <br />5.82926e-4 months <br />, Main Condenser [EIIS-SG,COND] B outlet isolation valve 1-CW-MOV-1008 [EIIS-SG,ISV] was opened to return the Main Condenser B to service.

During the afternoon of October 6, 1995, the Unit 2 Senior Reactor Operator (SRO) and Reactor Operator (RO) observed that the Unit 2 Containment temperature had increased from approximately 11 O degrees Fahrenheit (F) at the beginning of the Shift to approximately 112 degrees F. They also observed that the SW temperature had increased and noted that it had been a relatively warm day compareo to the previous week. The Unit 1 Turbine Building Operator verified that the CCHX SW inlet and outlet valves were fully open. The Unit 2 SRO and RO concluded from this information that the increase in Containment temperature was attributable to the increase in SW and outside ambient air temperature.

The increase in Unit 2 Containment temperature was discussed during Shift turnover to

  • the nightshift. Recommendations for providing additional cooling to Unit 2 Containment were also discussed. The continued increase in the Unit 2 Containment temperature during nightshift was noted and was being investigated.

At 2020 hours0.0234 days <br />0.561 hours <br />0.00334 weeks <br />7.6861e-4 months <br /> on October 6, 1995, the Alert radiation monitoring alarm was received for the CCHX C SW Radiation Monitor [EIIS-IL]. The alarm indicates that either Component Cooling (CC) water is leaking into SW or that little or no water is in the SW discharge side of the CCHX to provide shielding to the in-line SW radiation monitor.

CCHX C was isolated and, in accordance with the annunciator response procedure, a sample of the SW side was taken to detect possible tube leakage. The integrity of the heat exchanger was confirmed when analysis results did not detect radioactive material in the sample. Suspecting CCHX tubesheet fouling, Operations initiated testing of the CCHX C.

NRC FORM 366 r-U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB NO. 3150-0104 EXPIRES 5/31/95 (5-92)

LICENSING EVENT REPORT (LER)

(See reverse for required number of digits/characters for each block)

FACILITY NAME 111 DOCKET NUMBER 121 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001. AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

LERNUMBERl&l PAGEi~

YEAR SEQUENTIAL NUMBER REVISION NUMBER SURRY POWER STATION, Unit 1 05000 - 280 95

- 010 -

00 3oF6 TEXT (If more space is required, use additional copies of NRG Form 366A) (17) 1.0 DESCRIPTION OF THE EVENT (Continued)

At 2150 hours0.0249 days <br />0.597 hours <br />0.00355 weeks <br />8.18075e-4 months <br /> on October 6, 1995, the Alert radiation monitoring alarm was received for the CCHX A SW Radiation Monitor 1-SW-RM-107 A. At 2250 hours0.026 days <br />0.625 hours <br />0.00372 weeks <br />8.56125e-4 months <br />, the CCHX C failed the criteria for tubesheet macrofouling and the heat exchanger was declared inoperable.

A decision was made by Station Management to clean the CCHX C. Following cleaning, the CCHX C was tested satisfactorily and returned to service at 0055 hours6.365741e-4 days <br />0.0153 hours <br />9.093915e-5 weeks <br />2.09275e-5 months <br /> on October 7, 1995. Prior to returning CCHX C to service, Unit 1 Residual Heat Removal [EIIS-BP]

(AHR) discharge temperature had increased from 90 degrees F to 98 degrees F and Unit 2 Containment temperature had increased to approximately 117 degrees F. The Unit 2 SRO and RO observed CC temperatures at approximately 98 degrees F.

Following the return to service of the CCHX C, these temperatures immediately began decreasing to their pre-event values.

At 0151 hours0.00175 days <br />0.0419 hours <br />2.496693e-4 weeks <br />5.74555e-5 months <br /> on October 7, 1995, the CCHX A was tested to determine tubesheet macrofouling and found to be inoperable. At 0213 hours0.00247 days <br />0.0592 hours <br />3.521825e-4 weeks <br />8.10465e-5 months <br />, the CCHX B was tested and found to be inoperable. At 0242 hours0.0028 days <br />0.0672 hours <br />4.001323e-4 weeks <br />9.2081e-5 months <br />, the CCHX D was also tested and found to be inoperable. A 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Technical Specification 3.13.B action statement was entered on Unit 2 due to only one CCHX being operable. At 0505 hours0.00584 days <br />0.14 hours <br />8.349868e-4 weeks <br />1.921525e-4 months <br />, it was determined that the four CCHXs had been inoperable when the CCHX C had failed the macrofouling test.

Therefore, a 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> Technical Specification (TS) 3.0.1 action statement was entered retroactive to 2250 hours0.026 days <br />0.625 hours <br />0.00372 weeks <br />8.56125e-4 months <br /> on October 6, 1995. This action statement was determined to have been exited at 0055 hours6.365741e-4 days <br />0.0153 hours <br />9.093915e-5 weeks <br />2.09275e-5 months <br /> on October 7, 1995, when the CCHX C was returned to service.

The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> TS 3.13.B action statement for Unit 2 was exited at 0544 hours0.0063 days <br />0.151 hours <br />8.994709e-4 weeks <br />2.06992e-4 months <br /> when CCHX A was cleaned, tested, and returned to service. The CCHX D and CCHX B were

  • cleaned, tested and returned to service at 1145 hours0.0133 days <br />0.318 hours <br />0.00189 weeks <br />4.356725e-4 months <br /> and 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br />, respectively, on October 7, 1995. A Root Cause Evaluation (RCE) team was established to investigate the cause of the event.

This event is being reported pursuant to 1 OCFR50.73(a)(2)(i)(B), conditions prohibited by plant Technical Specifications and 1 OCFR50.73(a)(2)(vii), since a single cause resulted in two independent trains becoming inoperable in a single system designed to remove residual heat.

NRC FORM366 (5-92)

U.S. NUCLEAR REGULATORY COMMISSION LICENSING EVENT REPORT (LER)

(See reverse for required number of digits/characters for each block)

FACILITY NAME 11)

DOCKET NUMBER (2l SURRY POWER STATION, Unit 1 05000 - 280 TEXT (If more space is required, use additional copies of NRG Form 366A) (17)

2.0 SAFETY CONSEQUENCES AND IMPLICATIONS

APPROVED BY 0MB NO. 315<Hl104 EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

LEA NUMBER 16)

PAGE 13)

YEAR SEQUENTIAL NUMBER REVISION NUMBER 95

- 01 0 -

00 4 OF 6 The CC system does not perform a safety related function during design basis accident conditions. The system is an intermediate cooling system that provides heat removal for.

various components.

The CC system also provides removal of residual heat for achieving and maintaining cold shutdown. The degraded condition of the CC system may have extended the time required for a Unit 2 cooldown. Unit 1 had an alternate method of decay heat removal with at least one Low Head Safety Injection (LHSI) flowpath from the Refueling Water Storage Tank [EIIS-BP,TK]. At least one High Head Safety Injection (HHSI) flowpath was also available.

The event resulted in no safety consequences or implications. The data obtained during performance of the macrofouling test procedures was analyzed by Engineering. The analysis concluded that the actual heat removal capacity of the four CCHXs, prior to cleaning on October 6 and October 7, 1995, was adequate to remove the required heat loads of both units if the CC temperatures had been allowed to rise within design limits.

Unit 2 had the capability to achieve hot shutdown within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and cold shutdown would have been achieved within design basis requirements by taking routine actions to clean the CCHXs. Therefore, the health and safety of the public were not affected during this event.

3.0 CAUSE

The root cause of the four inoperable CCHXs on October 6, 1995, was CCHX SW tubesheet blockage by hydroids and other marine material from the HLIS B and the B 96 inch Circulating Water (CW) line. The physical evidence for tubesheet blockage was little or no SW flow through the CCHXs' tubes.

Blockage was indicated by the increasing CC temperatures and confirmed by failure of the macrofouling tests.

In addition, hydroids were removed from each of the CCHXs during cleaning.

The source of the hydroids and marine growth was identified as the HLIS B and B 96 inch CW line, since the CC temperatures did not begin to increase until approximately 1530-1600 hours on October 6, 1995. This was approximately four hours after the CCHX service water supply was swapped from the HLIS D to its alternate source from the HLIS B and corresponds with the return to service of Main Condenser B. CW flow rate was significantly increased through the 96 inch CW line when the Main Condenser B was returned to service.

NRG FORM366 (5-92)

U.S. NUCLEAR REGULATORY COMMISSION LICENSING EVENT REPORT (LER)

(See reverse for required number of digits/characters for each block)

FACILITY NAME 11 l DOCKET NUMBER 121 SURRY POWER STATION, Unit 1 05000 - 280 TEXT (IC more space is required. use additional copies or NRG Form 366A) (17) 3.0 CAUSE (Continued)

APPROVED BY 0MB NO. 3150-0104 EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF.

MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

LER NUMBER f6l PAGE 131 YEAR SEQUENTIAL NUMBER REVISION NUMBER 95

- 010 -

00 5 OF 6 Exposure of the hydroids on the walls of the HUS to air or exposure to stagnant water in the B 96 inch CW pipe will not kill the hydroids but will cause them to enter a dormant state.

The turbulence created due to the change in water velocity when the Main Condenser B was returned to service caused the pre-existing hydroids to break off.

When the condenser was returned to service, debris was swept towards the condenser, with some of it entering the SW supply line.

4.0 IMMEDIATE CORRECTIVE ACTIONS

. After determining that the CCHX C was inoperable, it was removed from service and cleaned. Following cleaning and testing, the CCHX C was returned to service at 0055 hours6.365741e-4 days <br />0.0153 hours <br />9.093915e-5 weeks <br />2.09275e-5 months <br /> on October 7, 1995. CC temperatures immediately began decreasing to their pre-event values.

Due to the observed temperature trends and the CCHX A SW Alert radiation monitoring alarm, the three remaining CCHXs were tested to determine their performance.

Each failed to meet the surveillance test criteria and were declared inoperable.

Due to only one CCHX being operable, a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Limiting Condition for Operation (LCO) on Unit 2 was entered at 0242 hours0.0028 days <br />0.0672 hours <br />4.001323e-4 weeks <br />9.2081e-5 months <br /> on October 7, 1995, in accordance with TS 3.13.B.

At 0505 hours0.00584 days <br />0.14 hours <br />8.349868e-4 weeks <br />1.921525e-4 months <br /> on October 7, 1995, a 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> LCO was entered on Unit 2 in accordance with TS 3.0.1 when it was determined that four CCHXs had been inoperable when CCHX C failed its test. The LCO was retroactive to 2250 hours0.026 days <br />0.625 hours <br />0.00372 weeks <br />8.56125e-4 months <br /> on October 6, 1995 and considered to have been exited at 0055 hours6.365741e-4 days <br />0.0153 hours <br />9.093915e-5 weeks <br />2.09275e-5 months <br /> on October 7, 1995 when the CCHX C was returned to service.

The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> LCO was re-entered until the CCHX A was returned to service at 0544 hours0.0063 days <br />0.151 hours <br />8.994709e-4 weeks <br />2.06992e-4 months <br />.

Following cleaning and testing, the CCHXs A, B, and D were returned to service by 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on October 7, 1995.

A station Deviation Report was submitted.

NRG FORM366 (5-92)

U.S. NUCLEAR REGULATORY COMMISSION llCENSING EVENT REPORT (LER)

(See reverse for required number of digits/characters for each block)

FACILITY NAME (1)

DOCKET NUMBER 121 SURRY POWER STATION, Unit 1 05000 - 280 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

5.0 ADDITIONAL CORRECTIVE ACTIONS

APPROVED BY 0MB NO. 3150--0104 EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB n14). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON. DC 20503.

LER NUMBER 161 YEAR SEQUENTIAL NUMBER 95

- 010 -

REVISION NUMBER PAGEl3l 00 6oF6 A Root Cause Evaluation (RCE) was initiated on October 8, 1995 to determine the

cause of the event

The results of the RCE were approved by the Station Nuclear Safety Operating Committee (SNSOC) on October 26, 1995.

6.0 ACTIONS TO PREVENT RECURRENCE Based on the results of the RCE, the procedures used to return Main Condensers B and D to service will be modified to reduce the impact of hydroids on the CCHXs following maintenance on the associated High Level Intake Structures.

7.0 SIMILAR EVENTS

None 8.0 MANUFACTURER/MODEL NUMBER None

9.0 ADDITIONAL INFORMATION

None

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