RS-19-052, Supplement to the Response to Request for Additional Information Regarding License Amendment Request to Remove Operating Mode Restrictions for Performing Surveillance Testing of the Division 3 Battery and High ..

Supplement to the Response to Request for Additional Information Regarding License Amendment Request to Remove Operating Mode Restrictions for Performing Surveillance Testing of the Division 3 Battery and High ..

ML19114A420
Person / Time
Site:	LaSalle
Issue date:	04/24/2019
From:	Demetrius Murray Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-19-052
Download: ML19114A420 (5)

Text

Exelon Generation 4300 Winfield Road Warrenville , IL 60555 630 65 7 2000 Office RS-19-052 10 CFR 50.90 April 24 , 2019 U.S . Nuclear Regulatory Commission ATTN: Document Control Desk Washington , DC 20555-0001 LaSalle County Station , Units 1 and 2 Renewed Facility Operating License Nos. NPF-11 and NPF-18 NRC Docket Nos. 50-373 and 50-374

Subject:

Supplement to the Response to Request for Additional Information Regarding License Amendment Request to Remove Operating Mode Restrictions for Performing Surveillance Testing of the Division 3 Battery and High Pressure Core Spray Diesel Generator References : 1. Letter from David M. Gullett (Exelon Generation Company, LLC) to U.S.

NRC, "License Amendment Request to Remove Operating Mode Restrictions for Performing Surveillance Testing of the Division 3 Battery and High Pressure Core Spray Diesel Generator," dated April 19, 2018

2. Email from B. Vaidya (U.S. NRC) to R. Sprengel (Exelon Generation Company, LLC), "Request for Additional Information (RAl)-LaSalle 1 and 2, EPID-L-2018-LLA-0162, LAR RE : Removal of Operating Mode Restrictions for Performing Surveillance Testing of the Div 3 Battery and HPCS DG," dated March 28, 2019

3. Letter from Dwi Murray (Exelon Generation Company, LLC) to U.S. NRC, "Response to Request for Additional Information Regarding License Amendment Request to Remove Operating Mode Restrictions for Performing Surveillance Testing of the Division 3 Battery and High Pressure Core Spray Diesel Generator," dated April 12, 2019 In Reference 1, Exelon Generation Company, LLC (EGC) requested an amendment to Renewed Facility Operating License Nos. NPF-11 And NPF-18 for LaSalle County Station (LSCS), Units 1 and 2, respectively. In Reference 2, the NRC requested that EGC provide additional information to support their review of the subject License Amendment Request. As noted in Reference 2, a response was requested by April 12, 2019 and provided in Reference 3.

A clarification call was held with the NRC on April 16, 2019 to discuss the response provided in Reference 3, and a revised response to EEOB RAI 3 is provided in Attachment 1. This revised response supersedes the response to EEOB RAI 3 submitted in Attachment 1 to Reference 3.

EGC has reviewed the information supporting the No Significant Hazards Consideration and the Environmental Consideration that was previously provided to the NRC in Reference 1. The

April 24, 2019 U.S. Nuclear Regulatory Commission Page2 additional information provided in this submittal does not affect the conclusion that the proposed license amendment does not involve a significant hazards consideration. This additional information also does not affect the conclusion that neither an environmental impact statement nor an environmental assessment need be prepared in support of the proposed amendment.

In accordance with 10 CFR 50.91, "Notice for public comment; State consultation,"

paragraph (b), EGC is notifying the State of Illinois of this additional information by transmitting a copy of this letter and its attachment to the designated State Official.

There are no regulatory commitments contained in this letter. Should you have any questions concerning this letter, please contact Ryan M. Sprengel at (630) 657-2814.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 241h day of April 2019.

R~

Dwi Murray Manager - Licensing Exelon Generation Company, LLC : Revised Response to Request for Additional Information - EEOB RAI 3 cc: Regional Administrator- NRC Region Ill NRC Senior Resident Inspector- LaSalle County Station Illinois Emergency Management Agency

ATTACHMENT 1 Revised Response to Request for Additional Information - EEOB RAI 3 In Reference 1, Exelon Generation Company, LLC (EGC) requested an amendment to Renewed Facility Operating License Nos. NPF-11 And NPF-18 for LaSalle County Station (LSCS) , Units 1 and 2, respectively. In Reference 2, the NRC requested that EGC provide additional information to support their review of the subject License Amendment Request. As noted in Reference 2, a response was requested by April 12, 2019 and provided in Reference 3.

A clarification call was held with the NRC on April 16, 2019 to discuss the response provided in Reference 3, and a revised response to EEOB RAI 3 is provided below. This revised response supersedes the response to EEOB RAI 3 submitted in Attachment 1 to Reference 3.

Reqyests for Additional Information EEOB RA/ 3 Section 8.3. 1, "AC Power Systems (Onsite)," of NUREG-0800, "Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: L WR Edition -

Electric Power," states, in part, that in reviewing the mode of operation where both power systems are being operated in parallel, the interlock scheme, including electrical protective relay coordination and settings, is closely examined to verify that the independence of the necessary redundant portions of the onsite power system is established upon a failure in the offsite power system. The event of concern under this mode of operation is an accident concurrent with a LOOP and a single failure preventing the opening of the feeder-isolation breaker through which the paralleling of the power systems was being accomplished. Because the signal to start the diesel generator sets is normally derived from undervoltage relays, and under this situation the voltage is maintained above the trip relay settings by the diesel generator under test, the remaining redundant diesel generators will not be commanded to start running. Consequently, the added capacity resulting from the connection of non-safety-related loads to the diesel generator under test will cause the tripping of this diesel due to overload or under-frequency. The end result could be the total loss of power to the safety buses.

Subsection 3.2. 1, "General Basis," of the LAR states, in part, that the effect on safety of performing the subject SRs for the Division 3 DG during plant operation is not significantly different than the effect on safety associated with the performance of other DG surveillances required by the TS that are not prohibited from being performed during plant operation. For example, SRs 3. 8. 1. 9, 3. 8. 1. 10, and 3. 8. 1. 17 are performed by paralleling the DG in test with offsite power, similar to the existing monthly run of the DG, which is conducted with the plant online.

It is not clear, during the online load rejection testing of the Division 3 DG, in which the DG is paralleled to the offsite power, what the impact is to the safety buses if an event of loss of offsite power (LOOP), with or without LOCA, occurs.

Please provide a discussion of how the Division 3 DG and its associated equipment, during the online load rejection testing, respond to a LOOP and/or LOCA signal and the impact of the equipment responses to the safety buses.

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ATTACHMENT 1 Revised Response to Request for Additional Information - EEOB RAI 3 Revised Response The Division 3 DG and its associated equipment, during the online load rejection testing will respond to a LOOP and/or LOCA signal in the same manner as it would during the normal monthly operability run (SR 3.8.1.3) of the DG which parallels the DG with offsite power. During the online load rejection testing , the Division 3 DG is paralleled with offsite power in the same alignment as during the monthly operability runs. Additionally, while paralleled with offsite power during online load rejection testing, the Division 3 DG voltage is maintained at the nominal 4010-4310 volts.

Per UFSAR Section 8.1.2.2, "In the event of loss of offsite power supplies to an ESF 4160- volt switch group, there are provisions for automatic tripping of offsite supply circuit breakers, automatic shedding of certain non-ESF loads, automatic starting of the diesel generator, and automatic closing of the diesel-generator supply circuit breaker." UFSAR Section 8.3.1 .1.2 further states "Division 3 loads are not shed following a loss of bus voltage , since the total connected bus load is within the capacity of the diesel-generator set." As such, if a LOOP were experienced during online load rejection testing while the DG was paralleled with offsite power, the Division 3 electrical loads are not tripped.

If a LOCA was experienced while the Division 3 DG was paralleled with offsite power during online load rejection testing , the Division 3 DG would remain running and supplying the bus and all trips, except for the DG differential overcurrent and engine overspeed , would be bypassed .

If a LOOP and LOCA were experienced while the Division 3 DG was paralleled with offsite power during online load rejection testing, the Division 3 DG would likewise remain running and supplying the bus and all trips , except for the DG differential overcurrent and engine overspeed, would be bypassed.

In the event of a LOOP without a LOCA followed by a failure of the feeder breaker from the offsite power source to the Division 3 bus to open during online load rejection testing, the Division 3 DG would respond in the same manner as it would if the condition were to occur during the monthly operability runs. An overcurrent condition would send a signal to trip the feeder breaker from the offsite power source followed by a trip of the Division 3 DG if the overcurrent condition still existed. The Division 1 and Division 2 emergency buses would automatically isolate from all supply sources.

In the event of a LOOP and LOCA, followed by a failure of the feeder breaker from the offsite power source to the Division 3 bus to open during online load rejection testing, the Division 3 DG would respond in the same manner as it would if the condition were to occur during the monthly operability runs. The Division 3 DG would continue to operate and supply the associated bus. An overcurrent condition would bring in a control room alarm and operators would be required per procedure to reduce DG load. The Division 1 and Division 2 emergency buses would automatically isolate from all supply sources.

If a LOOP was experienced while the Division 3 DG was operating unloaded (i.e. output breaker open) during online load rejection testing , the Division 3 DG output breaker would auto close and the DG would supply the Division 3 bus. Per procedure, operators would take action to remove testing leads and set the governor speed droop appropriately.

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ATTACHMENT 1 Revised Response to Request for Additional Information - EEOB RAI 3 If a LOCA was experienced while the Division 3 DG was operating unloaded during online load rejection testing, the Division 3 DG would continue to operate unloaded. All trips, except for the DG differential overcurrent and engine overspeed, would be bypassed . Per procedure, operators would take action to remove testing leads and set the governor speed droop appropriately.

If a LOOP and LOCA were experienced while the Division 3 DG was operating unloaded during online load rejection testing, the Division 3 DG output breaker would auto close and the DG would supply the Division 3 bus. All trips, except for the DG differential overcurrent and engine overspeed, would be bypassed. Per procedure, operators would take action to remove testing leads and set the governor speed droop appropriately.

In all scenarios, the equipment response of the Division 1 and Division 2 safety related equipment would not be impacted during Division 3 online load rejection testing .

References

1. Letter from David M. Gullett (Exelon Generation Company, LLC) to U.S. NRC, "License Amendment Request to Remove Operating Mode Restrictions for Performing Surveillance Testing of the Division 3 Battery and High Pressure Core Spray Diesel Generator," dated April 19, 2018

2. Email from B. Vaidya (U.S. NRC) to R. Sprengel (Exelon Generation Company, LLC),

"Request for Additional Information (RAl)-LaSalle 1 and 2, EPID-L-2018-LLA-0162 , LAR RE: Removal of Operating Mode Restrictions for Performing Surveillance Testing of the Div 3 Battery and HPCS DG," dated March 28, 2019

3. Letter from Dwi Murray (Exelon Generation Company, LLC) to U.S. NRC, "Response to Request for Additional Information Regarding License Amendment Request to Remove Operating Mode Restrictions for Performing Surveillance Testing of the Division 3 Battery and High Pressure Core Spray Diesel Generator," dated April 12, 2019 3