ML15026A132

Response to Request for Additional Information for CDBI Findings for License Amendment Request for Diesel Generator Initiation - Degraded Voltage Time Delay Setting Change

ML15026A132
Person / Time
Site:	Nine Mile Point
Issue date:	01/22/2015
From:	Orphanos P Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NMP1L 2995, TAC MF1022
Download: ML15026A132 (19)

Text

Exelon Generation.

NMP1 L 2995 10 CFR 50.90 January 22, 2015 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Nine Mile Point Nuclear Station, Unit 1 Renewed Facility Operating License No. DPR-63 Docket No. 50-220

Subject:

Response to Request for Additional Information for CDBI Findings for Nine Mile Point Nuclear Station License Amendment Request for Diesel Generator Initiation - Degraded Voltage Time Delay Setting Change

References:

(1) Letter from C. Costanzo (NMPNS) to Document Control Desk (USNRC), License Amendment Request Pursuant to 10 CFR 50.90:

Diesel Generator Initiation - Degraded Voltage Time Delay Setting Change, dated March 8, 2013 (ADAMS Accession No. ML13073A103)

(2) Letter from C. Costanzo (NMPNS) to Document Control Desk (USNRC), Second Supplement to Nine Mile Point Nuclear Station License Amendment Request for Diesel Generator Initiation -

Degraded Voltage Time Delay Setting Change, dated August 29, 2014 (ADAMS Accession No. ML14251A233)

(3) Letter from N. Morgan (USNRC) to C. Costanzo (NMPNS), Request for Additional Information Regarding the Diesel Generator Initiation -

Degraded Voltage Time Delay Setting Change License Amendment Request (TAC No. MF1 022), dated December 10, 2014 (ADAMS Accession No. ML14342A097)

Nine Mile Point Nuclear Station, LLC (NMPNS) hereby transmits supplemental information requested by the NRiC Staff in support of a previously submitted request for amendment to the Nine Mile Point Unit 1 (NMP1) Renewed Facility Operating License DPR-63. The initial request, dated March 8, 2013 (Reference 1) included a revision to the NMP1 degraded voltage time delay setting change. The initial request was supplemented on August 29, 2014 (Reference 2) to provide the results of the final degraded voltage study.

The supplemental information, provided in the Attachment to this letter, responds to the request for additional information for the 2014 Component Design Basis Inspection (CDBI) findings provided in the letter from the NRC Staff to NMPNS on December 10, 2014 (Reference 3). The RAI responses utilized the final degraded voltage study results previously submitted in Reference 2.

U. S. Nuclear Regulatory Commission January 22, 2015 Page 2 This supplemental letter does not change the initial determination of "no significant hazards consideration" justified in the original amendment request, Reference (1). Pursuant to 10 CFR 50.91 (b)(1), NMPNS has provided a copy of this supplemental information to the appropriate state representative.

This letter contains no new regulatory commitments.

Should you have any questions regarding the information in this submittal, please contact Terry Syrell, Manager Regulatory Assurance, at (315) 349-5245.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 2 2 nd day of January, 2015.

Respectfully, Peter M. Orphanos Site Vice President - Nine Mile Point Exelon Generation Company, LLC PMO/KJK

Attachment:

Response to NRC Request for Additional Information for CDBI Findings cc: Regional Administrator, Region I, USNRC Project Manager, USNRC Resident Inspector, USNRC A. L. Peterson, NYSERDA

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS Nine Mile Point Nuclear Station, LLC January 22, 2015

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS By letter dated March 8, 2013, Nine Mile Point Nuclear Station, LLC (NMPNS) requested NRC approval to implement a degraded voltage time delay setting change at Nine Mile Point Unit 1 (NMP1) in accordance with 10 CFR 50.90. Specifically, the proposed amendment would modify Technical Specification (TS) Table 3.6.2i, "Diesel Generator Initiation," by revising the existing 4.16kV Power Board 102/103 Emergency Bus Undervoltage (Degraded Voltage) Operating Time value and updating the Set Point heading title. This attachment provides supplemental information in response to the request provided in a letter from the NRC Staff to NMPNS on December 10, 2014. The introduction to the RAls is repeated below (in italics). Each individual NRC question is repeated (in italics), followed by the NMPNS response.

Inspection Report No. 05000220/2014007describes the following findings/violationsfor NMP1 with respect to the failure to implement design control measures to verify that the connected Class 1E loads would not be damaged or become unavailablefor a design-basis Loss of CoolantAccident (LOCA) coincident with a sustaineddegraded voltage condition:

1. Failure to adequately evaluate the transientvoltages to the Class 1E accident initiated motors and motor operated valves (MOVs) on the-safety relatedbuses and motor control centers (MCC's). Specifically, Exelon calculations incorrectly used 115 kilovolts (kV) grid voltage insteadof incorporatingthe 3.5% grid voltage sag into calculationNIMO-ELMS-AC01. Consequently, the licensee did not verify and assure adequate voltages would be available to Unit 1 Class 1E accident initiatedmotors, MOVs, and control circuits powered from the 4160 V, 600 V, and 120 V distribution systems during a design-basis LOCA with subsequent unit trip and resulting sag of the 115 kV grid.

2. The inspection team noted that the NMP1 electricaldesign calculations had not evaluated for the following conditions:

a. Connected Class 1E loads would not be degraded or renderedinoperable for a design-basis LOCA and a sustained degraded voltage condition between the degraded voltage dropout setting (3705 V) and the loss of voltage setting (3200 V) for the degraded voltage time delay of 21 +/- 3 seconds and subsequent reconnection to the emergency diesel generator.

b. Safety-related equipment that is operating or safety-relatedloads that are requiredto start (motors, MOVs, etc.) had not been evaluated to ensure that their protective devices would not actuate during a sustained degradedgrid condition coincident with a design basis LOCA.

For the conditions identified above, the requiredequipment may not be availableafter transfer of safety busses to the onsite power sources.

1 of 16

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS

RAI 1

For CDBI finding 1 above, provide a summary of the preliminary evaluationsprovided during the CDBI to verify that the critical Class 1E loads that operate during the first 24 seconds of a LOCA would not be damaged or become unavailable for a design basis LOCA coincident with a sustained degraded voltage condition. Clearly identify each input and assumption used for each preliminaryevaluation, including load tap changerperformance during the 24 second period.

Response RAI 1 In Reference 2, Nine Mile Point Nuclear Station, LLC (NMPNS) submitted to the NRC additional information regarding the conclusions of formal calculations associated with degraded voltage conditions at Nine Mile Point Unit 1 (NMP1). The conclusions validated that all safety related equipment will operate during degraded voltage conditions at the degraded voltage setting of 3705V during the first 21 +/- 3 seconds. During the recent 2014 CDBI inspection, it was noted that the same formal calculation used 115KV as a design input instead of incorporating the 3.5% grid voltage sag into the calculation. The results of the calculation using the 3.5% grid voltage sag did not change the previous conclusions provided in Reference 2 that all safety related equipment will operate during degraded voltage conditions at the degraded voltage setting of 3705V during the first 21 +/- 3 seconds. The acceptance criteria noted in Reference 2 for this equipment was still achieved after incorporating the 3.5% grid voltage sag. The evaluations supporting this conclusion are included in Enclosure 1, Equipment Technical Evaluations.

2 of 16

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS

RAI 2

For CDBI finding 2 above, provide a summary of preliminaryevaluationsperformed to evaluate conditions 2.a and 2.b describedabove. Clearly identify each input and assumption used for each preliminaryevaluation.

Response RAI 2 Conditions 2.a and 2.b above were evaluated using a preliminary eTAP scenario utilizing the formal calculation, NIMO-ELMS-AC01 Revision 1, "Performance of the Electrical Auxiliary System." This preliminary eTAP model was used to validate that the safety-related equipment that are required to perform their function during the first 24 seconds during a sustained degraded voltage condition concurrent with a unit trip and LOCA would not be degraded, rendered inoperable and/or would not actuate their protective devices. The preliminary eTAP scenario simulated the 4160V power boards at 3200V which is the Loss of Voltage Relay (LVR) setpoint. This provides the minimum voltage at the terminals for the loads before separating from the power grid.

The methodology for determining the Class 1E motor loads would withstand a sustained degraded voltage condition without compromising the protective device function is based upon proving the motors would not stall during the Degraded Voltage Relay (DVR) time delay of 21

+/- 3 seconds. The criterion of motor stall was selected because it results in the protective device being subjected to a locked rotor current (LRA) condition for a time period that may be great enough to challenge protective devices. The conclusion is that all connected Class 1 E loads would not be degraded or rendered inoperable for a design-basis LOCA and a sustained degraded voltage condition between the degraded voltage dropout setting (3705V) and the loss of voltage setting (3200V) for the degraded voltage time delay of 21 +/- 3 seconds and subsequent reconnection to the emergency diesel generator. The evaluations supporting this conclusion are included in Enclosure 1, Equipment Technical Evaluations.

3 of 16

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS

RAI 3

For CDBI findings 1 and 2 above, please provide corrective actions planned and taken, including the review of the extent-of-condition for components requiredduring a LOCA.

Response RAI 3 Incorporation of the preliminary findings into the necessary calculations and design documents is being tracked as part of the station's corrective action program.

Actions taken:

1. Issued a modification increasing the circuit breaker sizing for select Core Spray MOVs.

Increasing the breaker size will provide additional design margin for MOV operation during degraded voltage conditions for these valves.

2. An updated grid voltage analysis has been received from the transmission operator. This analysis identifies the grid voltage sag of 3.5%.

Actions planned:

1. The updated grid voltage analysis will be used as the basis for calculation updates to ensure grid voltage sag is documented and addressed for degraded voltage scenarios.

2. Update the formal eTAP calculation to include case models that address safety related equipment and protective device operation between the degraded voltage relay setpoint of 3705V and loss of voltage relay setpoint of 3200V.

3. Develop and issue calculation(s) for MOV contactors and include evaluation of control circuit protective fusing.

An extent of condition evaluation was performed to identify the Class 1 E safety related components required to perform their safety function within the first 24 seconds of degraded voltage conditions. The components identified for this extent of condition will be addressed in formal engineering evaluations.

4 of 16

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS Enclosure 1, Equipment Technical Evaluations 5 of 16

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS Motor Operated Valves (MOVs) and Control Circuits Evaluation (RAI 1):

This evaluation was performed during the 2014 NRC CDBI.

This evaluation focuses on MOV and Control Circuits since previous evaluations on 4KV SR motors were minimally affected and those results were provided to the NRC and were not questioned during the 2014 CDBI.

This evaluation considers only the first 24 seconds of degraded voltage conditions. The basis for 24 seconds is the current degraded voltage relay setpoint of 21 +/-3 seconds. The longest calibration uncertainty of 3 seconds is conservatively assumed and added to the nominal 21 second setpoint. The transient degraded voltage condition during a unit trip plus a concurrent double ended recirculation line break LOCA is also assumed in this analysis. Should degraded voltage conditions exceed 24 seconds, the degraded voltage relays will operate and transfer the loads to the emergency diesel generator. The MOVs in Table 1 have been identified in NIMO-ELMS-AC01 Revision 1 as operating in the first 24 seconds. Therefore, these valves are potentially vulnerable to the scenarios described above.

Table 1 MOVs Required to Operate in First 24 Seconds of a Unit 1 SCRAM with Concurrent LOCA MOV Description IV-01-01 MOTOR OPERATED MAIN STEAM INSIDE ISOLATION VALVE 1 IV-01-02 MOTOR OPERATED MAIN STEAM INSIDE ISOLATION VALVE 2 IV-33-01R MOTOR OPERATED CLEANUP RETURN ISOLATION VALVE ( INSIDE)

IV-33-02R MOTOR OPERATED CLEANUP SUPPLY ISOLATION VALVE II (INSIDE)

IV-83.1-09 MOTOR OPERATED DRYWELL EQ DRAIN TANK OUTLET INSIDE ISOLATION VALVE

- WASTE COLLECTOR TANK ISOLATION VALVE IV-83.1-11 MOTOR OPERATED DRYWELL FLOOR DRAIN SUMP ISOLATION VALVE - FLOOR DRAIN COLLECTOR TANK ISOLATION VALVE IV-40-01 MOTOR OPERATED CORE SPRAY SYSTEM 12B INLET TO REACTOR VESSEL ( CR)

ISOLATION VALVE IV-40-09 MOTOR OPERATED ISOLATION VALVE - CORE SPRAY SYSTEM 12A INLET TO REACTOR VESSEL IV-40-10 MOTOR OPERATED ISOLATION VALVE - CORE SPRAY SYSTEM 11A INLET TO REACTOR VESSEL ( CR )

IV-40-11 MOTOR OPERATED ISOLATION VALVE - CORE SPRAY SYSTEM 11B INLET TO REACTOR VESSEL ( CR )

6 of 16

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS Utilizing the transient degraded voltage from the preliminary eTAP scenario that models the grid voltage sag of 3.5% for a unit trip with a LOCA and using a degraded voltage condition of 3200V. The resultant terminal voltages, excluding the core spray MOVs, are shown below.

Since the core spray MOVs have associated interlocks required for operation, they are addressed later in this evaluation.

MSIV IV-01 72.34% of Rated Motor Voltage MSIV IV-01 80.57% of Rated Motor Voltage MOV IV-33-01 R - 71.01% of Rated Motor Voltage MOV IV-33-02R - 80.82% of Rated Motor Voltage MOV IV-83.1 86.41% of Rated Motor Voltage MOV IV-83.1 86.41% of Rated Motor Voltage These voltages were input to the MOV Torque and Thrust Calculations. The minimum voltage needed for these MOVs to perform their function is lower than the eTAP scenario at 3200V.

The MOVs will have adequate voltage to perform the intended safety function operation of the valve. One assumption in this calculation is the contactor coils have adequate voltage to pick up. The contactor voltages acceptance criterion is 87V per procedure N1-EPM-GEN-182, "Motor Control Center Inspection." The MOV contactor coil voltages were calculated utilizing the voltages at power boards PB-161B and PB-171B after 24 seconds and the preliminary eTAP scenario modeling the grid voltage sag of 3.5% for a unit trip and LOCA. The results of the calculation show that the voltages to the contactor coils are all above 87V. The contactor coils will operate as designed during a unit trip and LOCA event concurrent with a degraded voltage time delay of 24 seconds.

Instrumentation for NMP1 Core Spray Injection Valves IV-40-09, IV-40-1 0, IV-40-01, and IV 11 has the following permissive that initiates Core Spray: reactor pressure of greater than or equal to 365 PSIG and either high drywell pressure or low-low reactor water level per NMP1 Technical Specification Table 3.6.2d. The pressure transmitters associated with the core spray injection valves discussed above are PT-36-08A, PT-36-08B, PT-36-08C, and PT-36-08D.

These transmitters provide an open permissive signal to actuate the valves. The pressure transmitters are calibrated on a two (2) year frequency per N1-ISP-036-108, "Hi Rx Pressure -

Emergency Cooling, Low RX Pressure Core Spray Permissive and MSIV SCRAM Closure Bypass." Table 2 below shows the "As found" and "As left" data from the last three calibrations of each of the pressure transmitters.

7 of 16

ATTrACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS Table 2 Pressure Transmitter Calibration Data PT-36-08A All Pressures in PSIG)

As found As left As found As left Minimum trip trip reset reset Guide value Allowable 2013 377.8 377.8 384 384 377 (365-389) 359.4 2011 382 375 389 383 377 (365-389) 356.3 2009 380 380 385 385 377 (365-389) 356.3 PT-36-08B (All Pressures in PSIG)

As found As left As found As left Minimum trip trip reset reset Guide value Allowable 2013 379.7 378.8 385.5 383.7 377 (365-389) 359.4 2011 380 380 386 386 377 (365-389) 356.3 2009 379 379 384 384 377 (365-389) 356.3 PT-36-08C (All Pressures in PSIG)

As found As left As found As left Minimum trip trip reset reset Guide value Allowable 2013 381.8 381.8 388.5 388.5 377 (365-389) 359.4 2011 381 381 386 386 377 (365-389) 356.3 2009 382 382 387 387 377 (365-389) 356.3 PT-36-08D (All Pressures in PSIG)

As found As left As found As left Minimum trip trip reset reset Guide value Allowable 2013 374.8 374.8 387.5 387.5 377 (365-389) 359.4 2011 380 380 387 1 387 377 (365-389) 356.3 2009 378 378 386 386 377 (365-389) 356.3 From Table 2, when the pressure transmitters were last calibrated in 2013, the "As left" values were within the acceptance range (Guide value) of 365-389 PSIG. The "As found" pressure transmitters were always found within the acceptance range with minimal drift seen.

Utilizing the transient degraded voltage from the preliminary eTAP scenario modeling the grid voltage sag of 3.5% for a unit trip and LOCA the Core Spray Valves resultant worst case terminal voltages with a time delay between 18 and 24 seconds are shown on Table 3. Based on Table 3, Core Spray Valves IV-40-09, IV-40-10, IV-40-01, and IV-40-11 will be capable of adequately performing their accident function. Therefore, Core Spray Valves IV-40-09, IV 10, IV-40-01, and IV-40-1 1 will not challenge their protective devices as the injection valve will never be in a condition resulting in sustained locked rotor current for unit trip and LOCA with a grid voltage sag of 3.5%.

The MOV contactor coil voltages for Core Spray Valves IV-40-09, IV-40-1 0, IV-40-01, and IV-40-11 were calculated utilizing the power boards PB-1 61 B and PB-1 71 B voltages with a time delay between 18 and 24 seconds from the preliminary eTAP scenario modeling the grid voltage sag of 3.5% for a Unit Trip and LOCA. The contactor voltage acceptance criteria is 87V per procedure N1-EPM-GEN-182 "Motor Control Center Inspection." As shown in Table 3, the 8 of 16

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS voltages to the contactor coils are all above 87V. Therefore, the contactor coils will operate as designed during a Unit Trip and LOCA event.

Table 3 Core Spray Injection Valve Voltages with a Grid Voltage Sag of 3.5% for a Unit Trip and LOCA Component IV-40-01 IV-40-09 IV-40-10 IV-40-11 Motor Rated 575 V 575 V 575 V 575 V Voltage Accident Open Open Open Open Function Lowest % of 75.0% 75.0% 80.0% 73.0%

Motor Rated Voltage to Complete Accident Function

% of Motor 86.22% 87.70% 86.04% 89.68%

Rated Voltage between 18 and 24 seconds Contactor Coil 91.88 V 94.28 V 91.97 V 95.44 V Voltage Load Tap Changer Evaluation:

The following evaluation was performed during the 2014 NRC CDBI utilizing the transient degraded voltage from the preliminary eTAP scenario that modeled the grid voltage sag of 3.5%

for a Unit Trip and LOCA:

The lowest transient voltage of 546.51V for PB-131A occurs during a unit trip and LOCA. The preliminary eTAP scenario indicates that the lowest transient voltage of 492.48V for PB-131B occurs during a unit trip and LOCA. The voltage for PB-1 31 B will be used as it bounds that of PB-1 31 A. This voltage is increased by approximately 2.5% due to the tap change that was performed on the upstream Reserve Transformers (Ref. Calc. Disp. NIMO-ELMS-AC01 -OAX).

This results in an expected voltage of approximately 504.792V (492.48V x 1.025 = 504.792V) for Power Board 131 B. Utilizing the worst case voltage of 504.792V, the expected worst case running voltage at the new distribution transformer would be approximately 502.192V (504.792V

- 2.6V = 502.192V). Converting this voltage to the load side of the distribution transformer (600V-240V), results in a voltage of approximately 200.877V (502.192V/2.5 = 200.877V). The resulting worst case running voltage at the transformer cabinet would be approximately 196.777V (200.877V - 0.5V - 3.6V = 196.777V). The calculated voltage of 196.777V represents 89.44% of 220V. The Reinhausen LTC equipment is rated for an input voltage of 208-240V. Utilizing the Vendor voltage tolerance of -15% and +10% voltage tolerance on the 208-240V rating results in an acceptable voltage range of approximately 176.8-264V. The transformer cabinet contains a step down transformer 240-240/120V. The tap changer voltage regulator is rated for an input voltage of 11 5V +25%, -35%. The terminal voltage calculated above is within the transformer auxiliary equipment voltage ranges.

9 of 16

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS The finalized degraded voltage study RAI Response provided in Reference 2 is still valid for the remaining loads to assure adequate voltage. The finalized degraded voltage study (ADC 000712-CN-001 NIMO-ELMS-AC01) is more conservative than the preliminary eTAP scenario that was used during CDBI that modeled a LOCA accident concurrent with a Unit Trip with a grid voltage sag of 3.5%. This scenario assumed the 4160V power boards 102 and 103 are floating just above 4000V prior to the start of the LOCA event. The finalized degraded voltage study evaluated the automatic sequencing of LOCA loads assuming the 4160V power boards 102 and 103 are floating just above 3705V prior to the start of the LOCA event.

Class 1 E Safety Related Equipment Operation during Sustained Degraded Grid Conditions between 3705V and 3200V (RAI 2)

The following evaluation was performed during the 2014 NRC CDBI utilizing the preliminary eTAP scenario developed that simulated the 4160V power boards at 3200V which is the Loss of Voltage Relay (LVR) setpoint for the SR Motors, MOVs and support equipment.

MOV Evaluations This section evaluates the safety related MOVs required to operate in the first 24 seconds of degraded voltage conditions.

MSIV MOV Evaluation In order to achieve adequate torque and thrust, MOV voltage must be at 46% of motor rated voltage for IV-01-01 and 51% of motor rated voltage for IV-01-02 per MOV calculations. When the 4160V bus is at 3200V, IV-01 -01 voltage will be at 80.57% and IV-01-02 will be at 72.34%

terminal voltage, which is adequate voltage.

MSIV 01-01 and 01-02 also have electric brakes coupled to the actuator motors (Brake 01-01 and Brake 01-02). The function of the brake is to prevent valve stem over-travel after the motor is de-energized. The information presented below shows that the brakes have adequate margin to perform their design function under degraded voltage concurrent with a LOCA conditions.

BRAKE-01 -01 & BRAKE-01 -02 are mounted on ACT-01-01 & ACT-01-02 respectively and rated at 50 ft-lb. Sufficient torque margin exists to operate the valves (IV-01-01 & IV-01-02) even in the event of the brake fail to release, as shown by the calculations below.

10 of 16

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS MSIV Motor Brake Calculations From S20.1-01V010-05, "IV-01-01 MOV Sizing Calculation":

MOV-01-01 Motor Reduced Rated Torque 138.92 ft-lb Mtr Terminal RV% 80.57%

Application Factor 0.9 Actuator Overall Gear Ratio 23.8 Actuator Pullout Efficiency 0.700 Reduced Voltage pullout Torque Capability - Design 1352.163 ft-lb Design Minimum Required Closing Stem Torque 599.8 ft-lb Margin (Reduced Voltage pullout Torque - Design minimum required) 752.4 ft-lb MOV actuator - ACT-01 -01 with brake not released:

Motor Reduced Rated Torque - Brake Holding Torque (138.92 - 50) = 88.9 ft-lb Mtr Terminal RV% 80.57%

Application Factor 0.9 Actuator Overall Gear Ratio 23.8 Actuator Pullout Efficiency 0.700 RV pullout Torque Capability with brake not released - Design 865.49 ft-lb Design Minimum Required Closing Stem Torque 599.8 ft-lb Margin (Reduced Voltage pullout Torque - Design minimum required) 265.7 ft-lb From S20.1-01 V020-05, "IV-01-02 MOV Sizing Calculation":

MOV-01 -02 Motor Reduced Rated Torque 138.92 ft-lb Mtr Terminal RV% 71.0%

Application Factor 0.9 Actuator Overall Gear Ratio 23.8 Actuator Pullout Efficiency 0.700 Reduced Voltage pullout Torque Capability - Design 1250.0 ft-lb Design Minimum Required Closing Stem Torque 635.3 ft-lb Margin (Reduced Voltage pullout Torque - Design minimum required) 414.7 ft-lb MOV actuator - ACT-01-02 with brake not released:

Motor Reduced Rated Torque - Brake Holding Torque (138.92 - 50) = 88.9 ft-lb Mtr Terminal RV% 71.0%

Application Factor 0.9 Actuator Overall Gear Ratio 23.8 Actuator Pullout Efficiency 0.700 Reduced Voltage pullout Torque Capability - Design 672.1 ft-lb Design Minimum Required Closing Stem Torque 635.3 ft-lb Margin (Reduced Voltage pullout Torque - Design minimum required) 36.8 ft-lb 11 of 16

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS IV-33-01 R and IV-33-02R Reactor Water Cleanup MOV Evaluation In order to achieve adequate torque and thrust the MOV's voltage must be at 71% of motor rated voltage for IV-33-01 R and 67% of motor rated voltage for IV-33-02R, per MOV calculations. The lowest percent of terminal voltages (bus voltage 3200V of 4160V) MOV IV 01R and MOV IV-33-02R will see are 71.01% (for IV-33-01 R) and 80.82% (for IV-33-02R).

These values are for a degraded voltage coincident with a LOCA conditions are adequate for the MOV's to achieve their desired operation.

IV-83.1-09 and IV-83.1-11 Drywell Sump MOV Evaluation In order to achieve adequate torque and thrust the MOV's voltage must be at 62% of motor rated voltage for IV-83.1-09 and 72% of motor rated voltage for IV-83.1-11, per MOV calculations. The lowest percentage of terminal voltages (bus voltage 3200V of 4160V) for MOV IV-83.1-09 and MOV IV-83.1-11 will be 86.41% (for IV-83.1-09 and IV-83.1-11). These values are for a degraded voltage coincident with a LOCA conditions are adequate for the MOV's to achieve their desired operation.

IV-40-01, IV-40-1 0, IV-40-01, and IV-40-11 Core Spray Valve MOV Evaluation Instrumentation for NMP1 Core Spray Injection Valves IV-40-09, IV-40-10, IV-40-01, and IV 11 have the following permissives that initiates Core Spray: reactor pressure of greater than or equal to 365 PSIG and either high drywell pressure or low-low reactor water level, per NMP1 Technical Specification Table 3.6.2d. The pressure transmitters associated with the core spray injection valves discussed above are PT-36-08A, PT-36-08B, PT-36-08C, and PT-36-08D.

These transmitters provide an open permissive signal to actuate the valves. As previously described, the pressure transmitters are calibrated on a two (2) year frequency per N1-ISP-036-108, "Hi Rx Pressure - Emergency Cooling, Low RX Pressure Core Spray Permissive and MSIV SCRAM Closure Bypass." The "As found" and "As left" data from the last 3 calibrations for each of the pressure transmitters was previously provided in Table 2 above.

From Table 2 above, when the pressure transmitters were last calibrated in 2013, the "As left" values were within the acceptance range of 365-389 PSIG. The "As found" values for the pressure transmitters were always found within the acceptance range with minimal drift seen.

12 of 16

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS Table 4 Core Spray Injection Valve Voltage Summary Component IV-40-01 IV-40-09 IV-40-1 0 IV-40-11 Motor Rated 575 V 575 V 575 V 575 V Voltage Accident Open Open Open Open Function Lowest % of 75.0% 75.0% 80.0% 73.0%

Motor Rated Voltage to Complete Accident Function

% of Motor 71.7% 72.3% 70.9% 74.7%

Rated Voltage at 3200V The lowest voltage the core spray injection valves would need to complete their accident function is shown in Table 4 (Lowest % of Motor Rated Voltage to Complete Accident Function).

An eTAP scenario was developed using NIMO-ELMS-AC01 Revision 1 model, to simulate the 4160V power boards at 3200V while starting the core spray injection valves as shown in Table 4

(% of Motor Rated Voltage at 3200V). The value of 3200V was used in the eTAP scenario because the Loss of Voltage Relay set point is 3200V per E130, "Device Set Point Specification." This is the minimum voltage present for the core spray injection valves before separating from the grid.

Based on Table 4, Core Spray IV-40-11 will be capable of adequately performing its accident function at 3200V. The voltage available at the motor for IV-40-11 at 3200V is 74.7% of 575V, which is adequate voltage to open the valve. Therefore, Core Spray IV-40-11 will not challenge its protective device as the injection valve will never be in a condition resulting in sustained locked rotor current.

The remaining core spray isolation valves (IV-40-01, IV-40-09, and IV-40-1 0) require further analysis since the rated voltage of the motor at 3200V falls below the required voltage necessary to complete their accident function. Therefore, to ensure these core spray valves will still be capable of performing their design function, breaker protective curves were reviewed while considering de-rated locked rotor conditions.

13 of 16

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS Table 5 Core Spray Injection Valve Voltage Summary Component IV-40-01 IV-40-09 IV-40-10 Motor Rated Voltage 575 V 575 V 575 V Accident Function Open Open Open Lowest % of Motor 75.0% 75.0% 80.0%

Rated Voltage to Complete Accident Function

% of 600V to 71.8% 71.8% 76.6%

Complete Accident Function Time for Thermal 12 Seconds 6.75 Seconds 5.6 Seconds Breaker Actuation at De-rated LRA The required percentage of 600V has been calculated for IV-40-01, IV-40-09, and IV-40-1 0 to perform their accident function as shown in Table 5 (% of 600V to Complete Accident Function).

The required % of 600V was used to de-rate the locked rotor current.

The calculated de-rated locked rotor current (LRA) for IV-40-01 is 50.4 amps (Rated LRA * % of 600V to Complete Accident Function). Utilizing the de-rated LRA, the protective device for IV-40-01 will actuate at approximately 12 seconds. IV-40-01 will not obtain an actuation signal until 18 seconds to meet the core spray initiation permissive. Therefore, IV-40-01 can withstand a degraded voltage of 3200V without tripping the protective device for up to the first 30 seconds (18 seconds + 12 seconds) of the event.

The calculated de-rated locked rotor current (LRA) for IV-40-09 is 48.4 amps (Rated LRA * % of 600V to Complete Accident Function). Utilizing the de-rated LRA, the protective device for IV-40-09 will actuate at approximately 6.75 seconds. IV-40-09 will not obtain an actuation signal until 18 seconds to meet the core spray initiation permissive. Therefore, IV-40-09 can withstand a degraded voltage of 3200V without tripping the protective device for up to the first 24.75 seconds (18 seconds + 6.75 seconds) of the event.

The calculated de-rated locked rotor current (LRA) for IV-40-1 0 is 53.7 amps (Rated LRA * % of 600V to Complete Accident Function). Utilizing the de-rated LRA, the protective device for IV-40-10 will actuate at approximately 5.8 seconds. IV-40-10 will not obtain an actuation signal until 18 seconds to meet the core spray initiation permissive. Therefore, IV-40-10 can withstand a degraded voltage of 3200V without tripping the protective device for up to the first 23.8 seconds (18 seconds + 5.8 seconds) of the event.

The worst case time (shortest time before operation following a unit trip and LOCA) of Core Spray Valves 40-09, 40-10, 40-01, and 40-11 is 18 seconds. Given the scenario of a degraded voltage condition resulting in a voltage of 3200V following a unit trip and LOCA, the degraded voltage relays will separate the safety related loads from the offsite power and start the diesel generator loading in 14 seconds +/- 3.7 seconds for a worst case of 17.7 seconds. Therefore, 14 of 16

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS the protective devices will not be challenged for Core Spray Valves 40-09, 40-10, 40-01, and 40-11 due to the expected operation time of the degraded voltage relays.

In conclusion, the result of the preliminary evaluation validated that the SR MOVs (IV-01 -01, IV-01-02, IV-33-01 R, IV-33-02R, IV-83.1-09, IV-83.1-11, IV-40-01, IV-40-09, IV-40-10, and IV 11) required for a postulated accident would not be damaged and their overcurrent protective device would not trip their respective breakers leaving them inoperable following successful transfer to the onsite supply when the off site supply is experiencing a sustained degraded voltage condition.

Motor Stall Evaluation The methodology for determining the Class 1E motor loads and their ability to withstand sustained degraded voltage without compromising their protective devices is based upon proving the motors would not stall during the DVR time delay. The motor stalling during a transient due to insufficient voltage for the motor to physically perform its function would result in the protective device seeing locked rotor current (LRA) for a time that may be great enough to trip the protective relaying.

Torque of a three phase induction motor is proportional to the square of the terminal voltage.

This can be derived from Equation 7-27 of Electric Machinery, fifth edition, Fitzgerald / Kingsley

/ Umas Copyright 1990, McGraw-Hill (ISBN 0-07-021134-5). Using the relation of 3 phase induction motor torque and its corresponding terminal voltage it was shown that a stall co-efficient exists that can be used in determining a motor's tendency to stall. If this co-efficient is greater than one (1), the motor will not stall. Conversely, ifthe co-efficient is less than one, the motor will have a tendency to stall. Therefore, if the co-efficient is less than one (1), LRA shall be considered until the degraded voltage relay times out.

Using known quantities of torque, rated motor voltage, and degraded terminal voltage, preliminary analysis has determined that the Class 1 E motors will not stall even at severely degraded voltage conditions.

Due to the limited vendor information the torque speed curve for some of the motors is not available. Therefore, NEMA MG-1 2011 minimum breakdown torque was utilized from Section 12.39, "Breakdown Torque of Single-Speed Polyphase Squirrel-Cage Medium Motors with Continuous Ratings." The voltages to the motors were obtained from the preliminary eTAP scenario as shown in the Table below, 'Terminal Voltage Magnitude at LVR Setpoint." This table shows the terminal voltage magnitude as a percentage of bus voltage for the above loads at the LVR setpoint. Utilizing the relationship that torque is proportional to the square of the terminal voltage; the preliminary analysis has determined that the Class 1 E motors will not stall utilizing the preliminary eTAP scenario at the Loss of Voltage relay setpoint as shown in the table.

15 of 16

ATTACHMENT RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FOR CDBI FINDINGS Table 6 Terminal Voltage Magnitude at LVR Setpoint Voltage Torque Stall?

at LVR Co-Load Description Setpoint efficient (3200V Minimum)

CSP 81-23 Core Spray Pump Motor 111 86.65 1.62 No EVEF 202-53 RBEV Exhaust Fan 11 Motor 83.06 1.85 No Aux. Oil Pump Motor - Oil Supply to Feed Pump 12 72.37 1.56 No REPAOP 51-165 CSP 81-24 Core Spray Pump Motor 112 79.75 1.38 No RBEV Exhaust Fan 12 Motor 77.62 1.61 No EVEF 202-33 CREVEF 210-02 Control Room Emergency Fan 12 Motor 76.47 1.57 No DFDSP 104-16 Drywell Floor Drain Sump Motor 83 2.05 No DEDTSP 105-05 Drywell Equipment Tank Pump Motor 12 85.45 2.35 No DFDSP 104-15 Drywell Floor Drain Sump Motor 76.83 1.76 No DEDTP 105-04 Drywell Equipment Tank Pump Motor 11 80.27 2.07 No RFP 29-03 DEGVOLT Feed Pump 12 Motor 78.8 1.34 No CSTP 81-50 Core Spray Topping Pump Motor 111 87.82 1.46 No CSTP 81-49 Core Spray Topping Pump Motor 112 86.66 1.42 No CSP 81-03 Core Spray Pump Motor 121 87.20 1.64 No CSP 81-04 Core Spray Pump Motor 122 85.94 1.60 No CSTP 81-51 Core Spray Topping Pump Motor 121 87.63 1.45 No CSTP 81-52 Core Spray Topping Pump Motor 122 86.36 1.41 No 16 of 16