05000247/LER-2016-010, Regarding Safety System Functional Failure Due to an Inoperable Containment Caused by a Through Wall Defect in a Service Water Supply Pipe Elbow to the 24 Fan Cooler Unit

Regarding Safety System Functional Failure Due to an Inoperable Containment Caused by a Through Wall Defect in a Service Water Supply Pipe Elbow to the 24 Fan Cooler Unit

ML17003A008
Person / Time
Site:	Indian Point
Issue date:	12/21/2016
From:	Vitale A Entergy Nuclear Operations, Indian Point
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-16-140 LER 16-010-00
Download: ML17003A008 (7)

LER-2016-010, Regarding Safety System Functional Failure Due to an Inoperable Containment Caused by a Through Wall Defect in a Service Water Supply Pipe Elbow to the 24 Fan Cooler Unit

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(ix)(A) 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)(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)
2472016010R00 - NRC Website

text

Indian Point Energy Center 450 Broadway, GSB

-===- Entergy P.O. Box 249 Buchanan, N.Y. 10511-0249 Tel (914) 254-6700 NL-16-140 December 21, 2016 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop O-P1-17 Washington, D.C. 20555-0001 Anthony J. Vitale Site Vice President

SUBJECT:

Licensee Event Report# 2016-010-00 "Safety System Functional Failure Due to an Inoperable Containment Caused by a Through Wall Defect in a Service Water Supply Pipe Elbow to the 24 Fan Cooler Unit" Indian Point Unit No. 2 Docket No. 50-247 DPR-26

Dear Sir or Madam:

Pursuant to 10 CFR 50.73(a)(1), Entergy Nuclear Operations Inc. (ENO) hereby provides Licensee Event Report (LER) 2016-010-00. The attached LER identifies an event where there was a safety system functional failure due to an inoperable Containment as a result of a through wall defect in a Service Water (SW) supply pipe elbow to the 24 Containment Fan Cooler Unit. This condition is reportable under 10 CFR 50.73(a)(2)(v). This condition was recorded in the Entergy Corrective Action Program as Condition Report CR-IP2-2016-06934.

NL-16-140 Docket No. 50-247

• Page 2 of 2 There are no new commitments identified in this letter. Should you have any questions regarding this submittal, please contact Mr. Robert Walpole, Manager, Licensing at (914) 254-6710.

Sincerely, AJV/cbr cc:

Mr. Daniel H. Dorman, Regional Administrator, NRG Region I NRG Resident Inspector's Office Ms. Bridget Frymire, New York State Public Service Commission

NRC FORM366 U.S. NUCLEAR REGULATORY APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (11-2015)

}'_,,.,,,,

COMMISSION

, the NRG may not conduct or sponsor, and a person is not required to respond to, the information

1. FACILITY NAME

~. DOCKET NUMBER r* PAGE Indian Point 2 05000-247 1 OF 5

14. TITLE: Safety System Functional Failure Due to an Inoperable Containment Caused by a Through

~all Defect in a Service Water Supply Pipe Elbow to the 24 Fan Cooler Unit

5. EVENT DATE

6. LER NUMBER 7, REPORT DATE

8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR I SEQUENTIAL I REV MONTH DAY YEAR FACILITY NAME DOCKET NUMBER NUMBER NO.

FACILITY NAME D9CKET NUMBER 11 21 2016 2016 -

010 00 12 21 2016

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that applv)

D 20.2201 (b)

D 20.2203(a)(3)(i)

D 50.73(a)(2)(ii)(A)

D 50.73(a)(2)(viii)(A) 1 D 20.2201 (d)

D 20.2203(a)(3)(ii)

D 50.73(a)(2)(ii)(B)

D 50.73(a)(2)(viii)(B)

D 20.2203(a)(1)

D 20.2203(a)(4)

D so.73(a)(2)(iii)

D 50.73(a)(2)(ix)(A)

D 20.2203(a)(2)(i)

D 50.36(c)(1)(i)(A)

D 50.73(a)(2)(iv)(A)

D 50.73(a)(2)(x)

10. POWER LEVEL D 20.2203(a)(2)(ii)

D 50.36(c)(1)(ii)(A)

D 50.73(a)(2)(v)(A)

D 73.71 (a)(4)

D 20.2203(a)(2)(iii)

D so.3s(c)(2)

D 50.73(a)(2)(v)(B)

D 73.71 (a)(s) 100<%

D 20.2203(a)(2)(iv)

D so.46(a)(3)(ii)

~ 50.73(a)(2)(v)(C)

D 73.77(a)(1)

D 20.2203(a)(2)(v)

D 50.73(a)(2)(i)(A)

D 50.73~a)(2)(v)(D)

D 73.77(a)(2)(i)

D 20.2203(a)(2)(vi)

~ 50.73(a)(2)(i)(B)

D 50.73(a)(2)(vii)

D 73.77(a)(2)(ii)

D 50.73(a)(2)(i)(C) 00THER Specify in Abstract below or in The pipe elbow for the SW supply to the 24 FCU is epoxy coated carbon steel located on approximately the 76 foot elevation in containment.

The through wall flaw was next to weld of the elbow to SW supply pipe.

The Containment Fan Cooler system consists of five 20 percent capacity FCUs located inside containment.

These FCUs are used for both normal and post-accident cooling of the containment atmosphere.

Each FCU consists of a motor, fan, cooling coils, dampers, duct distribution system and instrumentation and controls.

SW is supplied to the cooling coils of each FCU to perform the heat removal function.

During normal operation, SW is supplied to all five FCUs and one or more FCUs may be operated for containment cooling.

It is necessary to limit the ambient containment air temperature during normal operation to less than the limit specified in TS 3.6.5 (Containment Air Temperature)*.

An extent -of condition review determined there was no evidence of additional leakage at any other place on the 24 FCU supply or at any other* location in the other four FCU lines.

CAUSE OF EVENT

Pending completion of the root cause evaluation, the likely cause leading to the leak was corrosion due to a pin-hole defect in the elbow's internal epoxy coating.

The pipe elbow with the flaw resulted in.containment out leakage in excess of 10CFR50, Appendix J limits.

CORRECTIVE ACTIONS

The following corrective actions have been performed under the Corrective Action Program (CAP) to address the causes of this event:

• The defective elbow was removed, code weld repaired, recoated on the interior and reinstalled.

• This LER will be revised as necessary after completion of the root cause evaluation.

EVENT ANALYSIS

The event is reportable under 10 CFR 50.73(a) (2) (v) (C).

The licensee shall report any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to (C) Control the release of radioactive material.

This condition meets the reporting criteria because TS 3.6.1 Containment Operability was not met.

The pipe flaw leakage was determined to be greater than the 10 CFR 50, Appendix J allowable leak rate.

TS 3.6.1 (Containment) requires the containment to be operable in Modes 1-4.

TS Surveillance Requirement (SR) 3_.6.1.1 requires visual examinations and leakage rate testing in accordance with the containment Leakage Rate Testing Program specified in TS 5.5.15.

SR 3.6.1.1 leakage rate requirements comply with 10 CFR 50, Appendix J, Option B.

As SW is required in an accident, the SW to the FCU would not be isolated in DBA and the piping credited as a closed system inside containment for containment integrity.

NRG FORM 366 (11-2015)

Consequently, defects discovered within the FCU SW piping may adversely affect containment integrity and the ability to control releases of radioactive material.

The condition also meets the reporting criteria of 10 CFR 50.73(a) (2) (i) (B).

The licensee shall report any operation or condition which was prohibited by the plant's TS.

During the previous period of operation for an unknown period of time the SW pipe contained a through wall leak that did not meet code requirements.

This previously unrecognized condition required entry into TS 3.7.8 and corrective actions implemented to return the pipe to operable.

Failure to comply with the TS LCO and perform required actions is a TS prohibited condition.

PAST SIMILAR EVENTS A review of the past three years of Licensee Event Reports (LERs) for events that involved containment integrity due to flawed piping credited as a closed system inside containment identified two LERs. LER-2015-001-01 reported a Technical Specification prohibited condition and a Safety System Functional Failure (SSFF) due to a through wall leak on the 24 FCU motor cooler SW return line that results in exceeding the allowable leakage rate for containment.

This LER is similar as the SW pipe defect was in piping credited as a closed system for containment integrity.

However, the pipe material (copper-nickel) and function (motor cooler return) are different.

The direct cause was similar (pitting corrosion) but* the 'apparent cause was different (length of time to replace the copper-nickel piping) as this LER concerns epoxy coated carbon steel.

LER-2015-004 reported a SSFF due to an inoperable containment caused by a flaw on an elbow on the 24 FCUSW motor cooler return line.

SAFETY SIGNIFICANCE

This condition had no effect on the health and safety of the public.

There were no actual safety consequences for the event because there were no accidents or events du~ing the degraded condition.

~

There were no significant potential safety consequences of this event.

The leakage from the affected SW pipe was within the capability of the SW system to provide adequate SW flow to SW loads.

Current analysis for SW pipe failures are postulated to be limited to small through-wall leakage flaws as SW is defined as a moderate energy fluid system.

The SW leak would eventually drain to the containment sump.

The containment sumps have pumps with sufficient capacity to remove excessive leakage and instrumentation to alert operators to a degraded condition.

The containment consists of the concrete reactor building, its steel liner, and the penetrations through the structure.

The containment building is designed to contain radioactive material that might be released from the reactor following a design basis accident (DBA).

The containment building steel liner and its penetrations establish the leakage limiting boundary of the containment.

NRC FORM 366 (11-2015)

Maintaining the containment operable limits the leakage of fission product radioactivity from the containment to the environment.

The DBA analysis assumes that the containment is operable such that, for the DBAs involving release of fission product radioactivity, release to the environment is controlled by the rate of containment leakage.

The containment was designed with an allowable leakage rate of 0.1 percent of containment air weight per day.

Containment isolation valves form a part of the

.containment pressure boundary.

Two barriers in series are provided for each penetration so that no single credible failure or malfunction of an active component can result in a loss of isolation or leakage that exceeds limits assumed in the

safety analysis

One of these barriers may be a closed system such as the SW piping for the FCUs.

The only time containment integrity can be affected is post accident when the FCUs safety function is being performed and SW pressure for the FCU cooling piping and coils may fall below peak accident pressure.

Mitigation of radiation release by the degraded SW pipe pathway can be by use of radiation monitors R-46 and R-53 which monitor containment fan cooling water for radiation indicative of a leak from the containment atmosphere into the cooling water. If radiation is detected, each FCU heat exchanger can be individually sampled to determine the leaking unit.

The SW for the 24 FCU can be isolated to prevent radioactive effluent releases.

During the time the FCU SW piping was degraded there was no leakage out of containment.

NRG FORM 366 (11-2015)