ML17278A134

Duke Presentation for Public Meeting 09-20-17

ML17278A134
Person / Time
Site:	Mcguire, Catawba, McGuire
Issue date:	10/04/2017
From:	Duke Energy Corp
To:	Division of Operating Reactor Licensing
MMahoney, NRR/DORL/LPLII-1, 415-3867
References
Download: ML17278A134 (14)

Text

Catawba / McGuire Proposed Changes to Technical Specification 3.8.1, "AC Sources - Operating" September 20, 2017

Duke Energy Attendees Steven Capps (Site Vice President, McGuire)

Lee Keller (General Manager Nuclear Engineering, Catawba)

Chris Nolan (Director, Nuclear Regulatory Affairs)

Art Zaremba (Manager, Nuclear Fleet Licensing

) Jordan Vaughan (Fleet Regulatory Affairs

) Randy Tracey (McGuire Operations)

Stephen LaPointe (McGuire NSWS Engineer

) Aaron Michalski (Catawba Operations)

Brian Cauthen (Catawba NSWS Engineer) 2 2 Agenda Introductions Opening Remarks LAR History Duke Energy Response to NRC Issues Issue 1 Issue 2 Issue 3 Precedent 3

Opening Remarks Improved Safety Margin Large Capital Investment License Amendment Request Details 4

License Amendment Request (LAR) History LAR interactions between Duke and NRC staff:

LAR Pre-application meeting held on August 30, 2016 Duke Energy LAR submitted May 2, 2017 (ADAMS Accession No. ML17122A116)

NRC letter requesting supplemental information June 30, 2017 (ADAMS Accession No. ML17167A317)

Duke Energy LAR supplement submitted July 20, 2017 (ADAMS Accession No. ML17201Q132)

NRC acceptance letter for LAR August 10, 2017 (ADAMS Accession No. ML17226A002

) Duke Energy would like to focus the remainder of the presentation responding to and discussing the NRC staff's 3 issues regarding the CNS/MNS LAR.

5 Issue 1 Issue 1: "The following summary and examples explain the NRC staff's concern regarding Duke's request to change the definition of OPERABILITY for shared components at Catawba Nuclear Station." Request: "-With current TSs, if a Catawba unit had an inoperable EDG, the other unit (actually both units) would be forced into a required action (RA) for TS 3.7.8, allowing 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to restore the EDG before the other unit commenced the process to go to Mode 5-" Duke Energy Response:

Catawba current licensing basis (normal AND emergency power)

Catawba example with the 1A EDG inoperable Single pump flow balance condition for continued Unit 2 operation 6

Issue 1 NRC staff provided 2 examples to demonstrate the concern regarding Duke's request to change the operability requirements for shared components at Catawba Nuclear Station.

"Example 1:

Catawba Unit 1 takes EDG 1A out of service for potentially 14 days and enters the required actions (RA) for TS 3.8.1 B. Catawba Unit 2 would remain satisfying the TS 3.8.1 LCO and the shared system TS LCOs because none of the shared components are declared inoperable, particularly the 1A NSWS pump. If Unit 2 suffered a DBA in this situation, either a LOOP/LOCA or LOOP, either with a single failure of a Unit 2 component, i.e. either the 2B EDG, the 2B NSWS pump or a NSWS 2B ESS component, it seems that Unit 2 would not be able to mitigate the DBA because at most, one NSWS pump in each NSWS loop (A and B) would have power. Yet, TS Bases 3.7.8 requires both NSWS pumps on an NSWS loop to be OPERABLE in order for an NSWS train to be OPERABLE. Therefore, with only one NSWS pump operating in each NSWS loop, it is not clear how NSWS is capable to perform the NSWS safety function for unit 2. Additionally, it is not apparent how Unit 1 (non

-accident unit) which was in Mode 1, has enough NSWS to get to Mode 5.

Example 2:

Catawba Unit 1 takes EDG 1A out of service for potentially 14 days and enters the required actions (RA) for TS 3.8.1 B. EDG 1B becomes inoperable and Unit 1 enters RA for TS 3.8.1 E and then RA 3.8.1 G. Meanwhile Unit 2 continues to satisfy TS 3.8.1 LCO and the shared system TS LCOs continue to be satisfied because none of the shared components are declared inoperable. It appears that Unit 2 is not prepared to mitigate a DBA as required by 10CFR50.36 because neither NSWS loop would have the necessary number of NSWS pumps as stated in the TS Bases for 3.7.8, because with the LOOP each NSWS loop has a maximum of one NSWS pump per loop, when two NSWS pumps per loop are required

." 7 Issue 1 Duke Energy Response:

Nuclear Service Water System (NSWS) Terminology and Layout NSWS can perform its safety function in mitigating the consequences of a design basis event accounting for a single failure in the system (the worst single failure eliminates one loop of pumps)

One Pump Flow Balance Four NSWS pumps are needed to operate both units without entry into a Technical Specification 3.7.8, "Nuclear Service Water System (NSWS)" Action statement.

Two operating NSWS pumps are required to mitigate the consequences of a design basis event if both units are operating in Modes 1

-4. In other words, any two NSWS pumps have sufficient capacity to supply post

-LOCA loads on one unit and shutdown and cooldown loads on the other unit

. Given an inoperable NSWS pump or its associated emergency diesel generator for a given train, the NSWS is placed in an alignment such that the remaining operable NSWS pump on the given train is aligned to supply the loads required by one pump flow balance. Two operating NSWS pumps can supply all required cooling loads both currently and with the proposed change.

8 Issue 2 "When in Modes 1

-4, Catawba Technical Specification Bases (B 3.7.8), states both NSWS pumps in an NSWS loop must be OPERABLE in order for the associated NSWS trains to be OPERABLE. Therefore, one NSWS pump in an NSWS loop may not be able to supply enough service water to allow both NSWS trains in that NSWS loop to perform their safety functions during a design basis event (DBE). For example, if the 1A EDG is inoperable and there is a subsequent loss of offsite power, the remaining 2A NSWS pump may not be able to supply enough service water to allow the 1A and 2A NSWS trains to perform their safety functions.

However, since the 1B and 2B NSWS trains are OPERABLE, the DBE can be mitigated.

In the above scenario, where the A NSWS loop has only one NSWS pump (2A) and the 1A and 2A NSWS ESS trains may not be able to perform their safety functions during the DBE, the 2A EDG may not have sufficient cooling to be OPERABLE, similar to the 1A and 2A ESS trains.

Request: Considering the above scenario, the licensee is requested to specifically discuss the operability of the 2A EDG and the associated TS actions for Unit 2, when the 1A EDG is out of service for maintenance and a loss of offsite power occurs

." 9 Issue 2 Duke Energy Response

For the scenario given, the 1A EDG is inoperable and there is a subsequent loss of offsite power event. The concern is that the 2A EDG may not receive sufficient cooling to be operable

. One pump flow balance alignment described for Issue 1 still applies to the scenario for Issue 2 and ensures that both Unit 1 and Unit 2 components on the associated train receive adequate NSWS flow. The remaining 2A NSWS Pump would be aligned to supply the loads required by one pump flow balance which includes the 2A EDG. T he 2A EDG will have sufficient cooling and is considered fully operable for the scenario given.

10 Issue 3 Issue 3: "The licensee has added new Required Action (RA) B4, which states "Confirm at least one train of shared components has an OPERABLE emergency power supply." Assuming both Catawba units are in Mode 1, and the licensee makes the 1A emergency diesel generator (EDG) inoperable, identify which EDGs the licensee will confirm as OPERABLE to satisfy RA B4. Please Explain." 11 Issue 3 Duke Energy Response:

The intent of new Required Action (RA) B.4 is to confirm that 1B and 2B emergency diesel generators (EDGs) are operable and capable of supporting the "B" train of NSWS when the 1A EDG is inoperable.

Both the 1B and 2B Nuclear Service Water System (NSWS) Pumps are part of the "B" train of shared components.

With the proposed change, both the 1B and 2B NSWS Pumps must each have an operable emergency power supply (i.e., an operable EDG) when the 1A EDG is inoperable.

12 Precedent The following multi

-unit nuclear plants received approval for an extended EDG Completion Time (i.e., 14 days) and also have systems that are shared between the units:

Prairie Island (NRC SE dated May 30, 2007; ADAMS Accession No. ML071310023) 14 day Completion Time for one inoperable EDG Shared plant systems include cooling water, auxiliary feedwater system cross

-ties and instrument air LaSalle (NRC SE dated January 30, 2002; ADAMS Accession No. ML012780141) 14 day Completion Time for one inoperable EDG Shared plant systems include Standby Gas Treatment System, Control Room Area Filtration System and Control Room Area Ventilation Air Conditioning System Browns Ferry (NRC SE dated October 5, 2011; ADAMS Accession No. ML11227A258) 14 day Completion Time for one inoperable EDG Safety related shared systems are: Residual Heat Removal Service Water, Emergency Equipment Cooling Water, Standby Gas Treatment and Control Room Emergency Ventilation D.C. Cook (NRC SE dated September 30, 2005; ADAMS Accession No. ML052720032

) 14 day Completion Time for one inoperable EDG Essential Service Water System independent headers shared between two units Braidwood (NRC SE dated September 1, 2000; ADAMS Accession No. ML003749193) 14 day Completion Time for one inoperable EDG and Component Cooling Water System is shared 13 14