05000413/LER-2019-002, Condition Prohibited by Technical Specifications Due to Auxiliary Feedwater Sump Pump Conditions

Condition Prohibited by Technical Specifications Due to Auxiliary Feedwater Sump Pump Conditions

ML19161A254
Person / Time
Site:	Catawba
Issue date:	06/10/2019
From:	Simril T Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RA-19-0267 LER 2019-002-00
Download: ML19161A254 (7)

LER-2019-002, Condition Prohibited by Technical Specifications Due to Auxiliary Feedwater Sump Pump Conditions

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv), System Actuation 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) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
4132019002R00 - NRC Website

text

(_~ DUKE

~ ENERGY RA-19-0267 June 10, 2019 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555

Subject:

Duke Energy Carolinas, LLC Catawba Nuclear Station, Unit 1 Docket No. 50-413 Licensee Event Report (LER) 413/2019-002-00 Tom Simril Vice President Catawba Nuclear Station Duke Energy CN01VP I 4800 Concord Road York, SC 29745 o: 803.701.3340 f 803.701.3221 10 CFR 50.73 Pursuant to 10 CFR 50. 73(a)(1) and (d), attached is LER 413/2019-002-00, entitled "Condition Prohibited by Technical Specifications due to Auxiliary Feedwater Sump Pump Conditions."

This report is being submitted in accordance with 10 CFR 50.73(a)(2)(i)(B).

There are no regulatory commitments contained in this letter or its attachment.

This was no impact to the health and safety of the public.

If questions arise regarding this LER, please contact Sherry Andrews of Regulatory Affairs at (803) 701-3424.

Sincerely, Tom Simril Vice President, Catawba Nuclear Station Attachment

United States Nuclear Regulatory Commission Page 2 June 10, 2019 xc (with attachment):

C. Haney Regional Administrator U.S. Nuclear Regulatory Commission - Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, GA 30303 M. Mahoney NRC Project Manager (CNS)

U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop O-8B1A 11555 Rockville Pike Rockville, MD 20852-2738 J. Austin (without enclosure)

NRC Senior Resident Inspector INPO Records Center 700 Galleria Parkway, SE Suite 100 Atlanta, GA 30339-5943

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2018)

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

3.Page Catawba Nuclear Station, Unit 1 05000 413 1

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4. Title Condition Prohibited by Technical Specifications due to Auxiliary Feedwater Sump Pump Conditions

5. Event Date

6. LER Number

7. Report Date

8. Other Facilities Involved I

Sequential I Rev Facility Name Docket Number Month Day Year Year Number No.

Month Day Year None 05000 Facility Name Docket Number 4

11 2019 2019 -

002 -

0 6

10 2019 None 05000

9. Operating Mode

11. This Report is Submitted Pursuant to the Requirements of 10 CFR §: (Check all that apply) 20 2201 (b) 20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 20.2201{d) 20.2203(a)(3)(ii)

50. 73(a)(2)(ii)(B)

50. 73(a)(2)(viii)(B) 1 20.2203(a)(1) 20.2203{a){4}

50. 73(a)(2)(iii) 50.73(a)(2)(ix)(A) 20.2203(a)(2)(i) 50.36(c)(1)(i){A) 50.73(a)(2)(iv){A)

50. 73(a){2)(x) 1 o. Power Level

• 20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A)

50. 73(a)(2)(v)(A) 73.71(a)(4) 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(B) 73.71(a)(5) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(C)

73. 77(a)(1) 100

• 20.2203(a)(2)(v) 50.73(a)(2)(i)(A)

50. 73(a)(2)(v)(D) 73.77(a)(2)(i) 20.2203(a)(2)(vi)

[Z] 50.73(a)(2){i)(B) 50.73(a)(2)(vii)

73. 77(a)(2)(ii)

50. 73(a)(2)(i)(C)

Other (Specify in Abstract below or in The AFW System is configured into three trains. The AFW System is considered OPERABLE when the components and flow paths required to provide redundant AFW flow to the steam generators are OPERABLE. This requires that the two motor driven AFW pumps be OPERABLE in two diverse paths, each supplying AFW to separate steam generators. The turbine driven AFW pump is required to be OPERABLE with redundant steam supplies from two main steam lines upstream of the MSIVs, and shall be capable of supplying AFW to any of the steam generators. The piping, valves, instrumentation, and controls in the required flow paths also are required to be OPERABLE.

Technical Specification (TS) 3.7.5 governs the AFW system. Limiting Condition for Operation (LCO) 3.7.5 requires three AFW trains to be OPERABLE in MODE 1, 2, and 3; only one AFW train which includes a motor driven pump, is required to be OPERABLE in MODE 4, when steam generators are relied upon for heat removal. With one of the required AFW trains (pump or flow path) inoperable in MODE 1, 2, or 3 for reasons other than Condition A, action must be taken to restore OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Condition C states that when two AFW trains are inoperable in MODE 1, 2, or 3, the unit must be in MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Condition D states that when three AFW trains are inoperable in MODE 1, 2, or 3, LCO 3.0.3 and all other LCO Required Actions requiring MODE changes are suspended until one AFW train is restored to OPERABLE status and action shall be immediately initiated to restore one AFW train to OPERABLE status.

No other inoperable structures, systems, or components contributed to the event.

EVENT DESCRIPTION

On April 11, 2019, with the Unit 1 and Unit 2 operating at 100 percent power, the 1 B Motor Driven (MD) Auxiliary Feedwater (AFW) [BA] pit sump pump failed to start in manual and was non-operational. The pump impeller was found seized. Once the impeller was repaired, the pump operated as expected. The 1 B MDAFW sump pump was returned to service on May 1, 20-19.

At the time of the 1 B MDAFW sump pump failure, the associated 1 B MDAFW pump was not declared inoperable. A new Auxiliary Building flooding calculation subsequently has shown that, in the event of a feedwater line break in the interior doghouse coincident with a loss of offsite power, the sump pumps for all three trains of the AFW pump are required to maintain OPERABILITY of their associated pumps. Taking into consideration the specified function of the AFW sump pumps (as verified by the new flooding calculation), the 1 B MDAFW pump should have been declared inoperable for the corresponding times that the sump pump was out of service. Therefore, the 1 B MDAFW pump was inoperable for a period longer than the allowed 72-hour completion time of Technical Specification (TS) Limiting Condition for Operation (LCO) 3.7.5 (three AFW trains shall be OPERABLE), Condition B (One AFW train inoperable in MODE 1, 2 of 3).

An extent of condition review identified two instances where two trains of AFW were inoperable due to the associated non-functional sump pumps and/or MDAFW pump inoperability for a period longer than the allowed 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> completion time of TS LCO 3.7.5, Condition C (Two AFW trains inoperable in MODE 1, 2 of 3). The first instance occurred on April 11, 2019, when both the 1A and 1 B MDAFW sump pumps were out of service simultaneously. The 1A MDAFW sump pump was returned to service on April 12, 2019. The second instance occurred on April 17, 2019, when the 1B MDAFW sump pump was out of service at the same time as the 1A MDAFW pump was removed from service. The 1A MDAFW pump was returned to service on April 18, 2019.

Additionally, the extent of condition review identified one instance where all associated Unit 1 AFW sump pumps were non-functional. On January 19, 2019, during performance of a test procedure enclosure the Turbine Driven (TD) AFW pump #1 was declared inoperable due to both TDAFW #1 sump pumps discharge valves being closed. Additionally, both the 1A and 1 B MDAFW trains should have been declared inoperable due to closing their respective sump pump discharge valves. The test procedure resulted in a condition prohibited by TS with three inoperable AFW trains as action was not initiated to immediately restore one AFW train to OPERABLE status. The discharge valves were reopened at a later time on the same day (January 19, 2019).

Timeline of Events:

January 19, 2019 - 1 A and 1 B MDAFW sump pumps and 1 TDAFW sump pumps discharge valves procedurally closed January 19, 2019 - 1A and 1B MDAFW sump pumps and 1TDAFW sump pumps discharge valves procedurally opened April 10, 2019 - 1A MDAFW sump pump removed from service April 11, 2019 - 1 B MDAFW sump pump was removed from service for maintenance (returned to service on May 1, 2019)

April 12, 2019 - 1A MDAFW sump pump returned to service April 17, 2019 -1A MDAFW pump inoperable April 18, 2019 - 1A MDAFW pump returned to OPERABLE May 1, 2019 - 1 B MDAFW sump pump was returned to service May 30, 2019 - A new Auxiliary Building flooding calculation approved and issued concluding that, in the event of a feedwater line break in the interior doghouse coincident with a loss of offsite power, the sump pumps for all three trains of the AFW pumps are required to maintain OPERABILITY of their associated pumps.

CAUSAL FACTORS:

Inaccurate information existed in the AFW Design Basis Specification, which stated that the MDAFW sump pumps are not required for the OPERABILITY of the AFW system. This caused a failure of recognizing the safety function of the MDAFW sump pumps, and their impact on the OPERABILITY of the MDAFW pumps.

Catawba Licensee Event Report (LER) 2008-001 described an event where flow restrictor cover plates were not installed for the interior doghouse floor drains. The LER identified the cause as inaccurate and non-conservative information in the original design basis calculation for sizing the floor drain flow restrictor plates. Evaluations performed in support of LER 2008-001 demonstrated that the AFW sump pumps are necessary to mitigate flooding of the AFW pumps in the event of a Main Feedwater (MFW) rupture. The AFW Design Basis Specification was not updated to reflect these details, resulting in failure to recognize the safety function of the MDAFW pump sump pumps and their impact on the OPERABILITY of the MDAFW pumps.

CORRECTIVE ACTIONS

Immediate The 1 B MDAFW sump pumps were repaired and returned to service - Complete An extent of condition review was performed to identify previous instances of non-functional MDAFW sump pumps, inoperable MDAFW pumps and/or inoperable TDAFW pumps. Procedures were also reviewed to determine equipment out of service. The results were cross-referenced to verify available trains of AFW - Complete Planned Resolve the design basis documentation and procedures to capture the safety significance of the AFW sump pumps as described in the new Auxiliary Building flooding calculation.

A cause analysis will be performed to determine why the safety significance of the AFW sump pumps was not recognized.

SAFETY ANALYSIS

During the period of review, while various times existed that the AFW sump pumps were unavailable or non-functional, the AFW system was always available to perform its required safety function. No damage to AFW equipment occurred.

This event is considered to be of very low safety significance as decay heat removal was not challenged. There was no impact to the health and safety of the public. Page 5

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