HNP-11-074, Initial Exam 2011-301 Post Exam Comments

Initial Exam 2011-301 Post Exam Comments

ML112170235
Person / Time
Site:	Harris
Issue date:	08/02/2011
From:	Scott S Progress Energy Carolinas
To:	Widmann M NRC/RGN-II
References
50-400/11-302, HNP-11-074
Download: ML112170235 (23)

Text

j Progress Energy July 25, 2011 SERIAL: HNP-1 1-074 Mr. Malcolm Widmann, Region II United States Nuclear Regulatory Commission 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, GA 30303-1257 SHEARON HARRIS NUCLEAR POWER PLANT DOCKET NO. 50-400/RENEWED L1CENSE NO. NPF-63 REACTOR AND SENIOR REACTOR OPERATOR INITIAL EXAMINATIONS 05000400/2011302

Dear Mr. Widmann:

Enclosed is the post-examination package for the Reactor and Senior Reactor Operator Initial Examinations given at the Harris Nuclear Plant July 11, 2011, through July 20, 2011.

Included from the administration of the Written Examination are the student cover sheets, answer sheets, master examinations, an answer key, a log of applicant questions and answers, and the student seating chart. Also, pertaining to the RO Written Examination, are three post-examination comments (Question #26, #48 and #49).

If you have any questions regarding this submittal, please contact Mr. Simon Schwindt at (919) 362-3527.

Sincerely,

/Scotty Scott Superintendent Operations Training Harris Nuclear Plant JMS/mgw Enclosures C: Mr. J. D. Austin (NRC Senior Resident Inspector, HNP) w/o Enclosures Mr. V. M. McCree (NRC Regional Administrator, Region II) w/o Enclosures Mrs. B. L. Mozafari (NRR Project Manager, 1-INP) w/o Enclosures

ØUL 2c 2fl Progress Energy Carolinas, Inc.

Harris Nuclear Plant P. 0. Box 165 New Hill, NC 27562 JUL 26 2011

Mr. Malcolm Widmann SERIAL: HNP-l 1-074 bc: (w/o Enclosures)

Mr. D. L. Griffith Mr. M. G. Wallace Mr. W. D. Gunter Mr. S. Schwindt Mr. W. Jefferson, Jr. Mr. F. L. Womack Mr. E. J. Kapopoulos, Jr. Licensing File(s) (2 copies)

Mr. B. C. McCabe Nuclear Records Ms. T. M. Midgette

HNP Licensed Operator Written Exam question #26 Post Exam Comment Comment for question # 26 is both answers A and B are correct. In the HNP EOP users guide the bases for the 100°F/hr cooldown rate limit is stated as follows: EOPs that provide instructions for plant cooldown and depressurization to cold shutdown conditions limit the RCS cooldown rate to 100°F/hr consistent with the Tech Spec limits for Modes 1 3. This basis confirms answer A is correct. The stem of the question states that an EPP-009 Post LOCA Cooldown and Depressurization is in progress. The bases document for EPP-009 (ES-I .2),

states that the maximum cooldown rate of 100°F/hr will preclude violation of the Integrity Status Tree thermal shock limits. FRP-P.I, RESPONSE TO IMMINENT PRESSURIZED THERMAL SHOCK, would be the procedure entered if the Integrity Status Tree limits were violated which would also make answer B Correct. Since the stem of the question did not specify whether the basis for the limit of 457°F at 0630 or the basis for the limit in EPP-009 was desired, either answer could be considered correct based on the reference used to answer the question. EPP 009 basis document was not referenced in the development of this question and this new technical information supports accepting both answers as correct.

Attached:

HNP Written Exam question #26 EPP-009, Post LOCA Cooldown and Depressurization Rev 18 page 12 EOP Users Guide Rev 30 page 46 ES-i .2 HP-Rev 2 page 81

O1.1 HNP RQ NRC Wdtten xrn.

26. Given the following plant conditions:

- At 0530, RCS temperature was being maintained at 557°F with the plant in Mode 3 when a Small Break LOCA occurred

- At 0545, RCS temperature is 550° F

- The crew is ready to commence a cooldown to cold shutdown lAW EPP-009, Post LOCA Cooldown and Depressurization Which ONE of the following identifies (1) the lowest allowable temperature of the RCS at 0630 if the crew begins the MAXIMUM permissible cooldown rate AND (2) the basis for this temperature limit?

A. (1)457°F (2) to ensure that Tech Spec cooldown limits are NOT exceeded B. (1)457°F (2) to ensure that a transition is NOT required to be made to FRP-P.1, Response to Imminent Pressurized Thermal Shock C. (1)450°F (2) to ensure that Tech Spec cooldown limits are NOT exceeded D. (1) 450°F (2) to ensure that a transition is NOT required to be made to FRP-P.1, Response to Imminent Pressurized Thermal Shock 26

POST LOCA COOLDOWN AND DEPRESSURIZATION 1.

I INSTRUCTIONS RESPONSE NOT OBTAINED I

10. Initiate RCS Cooldown To Cold Shutdown:

LI a. Maintain cooldown rate in RCS cold legs LESS THAN 1000 F/HR LI b. Check RHR system OPERATING

- LI b. GO TO Step lOf.

IN SHUTDOWN COOLING MODE LI c. Cooldown using RHR.

LI d. Dump steam from intact SG(s) to supplement cooldown and cool SG(s).

LI e. GOTOStepII.

f. Check all of the following to f. Dump steam from intact SGs at determine if steam can be dumped using any of the following (listed in to condenser: order of preference):

LI

• Check any intact SG MSIV - LI 1) SG PORVs OPEN LI 2) Locally operate SG PORVs LI

• Check condenser available (C-9) using OP-126, MAIN STEAM, light (BPLB 3-3) LIT

- EXTRACTION STEAM, AND STEAM DUMP LI

• Steam dump control system - SYSTEMS, Section 8.2.

AVAILABLE LI 3) TDAFW pump LI GO TO Stepli.

LI g. Transfer steam dump to steam pressure mode using OP-126, MAIN STEAM, EXTRACTION STEAM AND STEAM DUMP SYSTEM, Section 5.3.

LI h. Dump steam from intact SGs to condenser using condenser steam dumps.

EOP-EPP-009 I Rev. 18 I Page 12 of 59

UERQUiQE.

6.19 Tech Spec Cooldown and PressurelTemperature Limits EOPs that provide instructions for plant cooldown and depressurization to cold shutdown conditions limit the RCS cooldown rate to 1000 F/HR consistent with the Tech Spec limits for Modes 1 3.-

This limit conflicts with the Tech Spec limit in Mode 4 of 50° F/HR.

Use of the less restrictive 100° F/HR limit in Mode 4 is acceptable for implementation of the EOPs even though it does not comply with Tech Spec. Justification for use of the 100° F/HR limit and non-compliance with Tech Specs is documented in Engineering Evaluation PCR-5275 and the response to AR 00022701. The justification is based in part on the fact that in Mode 4, Pressure-Temperature limits to protect vessel integrity have been developed for the 100° F/HR cooldown rate as well as the 50° F/HR used as the Tech Spec limit. The RCS pressurelimit for any given RCS temperature are slightly lower for the 100° F/HR case but well abdve those (actually near the PRZ SRV setpoint) expected to be present during an operator controlled RCS cooldown. HNP has decided to use the more restrictive limit in Mode 4 to provide more operational flexibility when LTOPS is placed in service. (References 2.2.3.4 and 2.2.3.24)

PCR-5275 also evaluated when it was necessar to place LTOPS in service during EOP implementation. The evaluation found that it is not necessary to enable LTOPS or rack out all but one CSIP breaker during cooldown related EOPs except the Natural Circulation Procedures EPP-005, 006, and 007. In these three procedures, it is necessary to comply with these Tech Spec limits.

In the event of a LOCA, SGTR, or secondary side break in which cooldown to cold shutdown is performed in accordance with the EOPs, the plant operations staff may elect to enable LTOPs and rack out the CSIP breaker even though this is not explicitly directed in the procedures. However, the operators must have control of RCS temperature and pressure to warrant performance of these actions.

6.20 Determining RCS Temperature and Cooldown Rate When monitoring RCS cooldown rates, use cold eg temperature.

When RHR is in the shutdown cooling mode AND RCPs are stopped, use RHR HX outlet temperature to determine cooldown rates. These are consistent with the temperature indications to be used as outlined in GP-007, Attachment 1.

In determining the RCS cooldown rate, the cold leg temperature change over the last 60 minutes must always beconsidered (Reference 2.2.2.5). For example, assume at the initiation of an accident the RCS cold leg temperature is 555° F. Thirty minutes into the accident, the EOPs direct a 100° F/Hr cooldown be commenced. The lowest cold leg temperature atthis time is 455° F.

Since a decrease of 100° F has already occurred, the operator must wait thirty more minutes to initiate the cooldown. However, implementation of other EOP actions should continue as allowed by the rules of usage discussed in Section 5.3.7.

EOP-USERS GUIDE I Rev. 30 I Page 46 of 69

STEP DESCRIPTION TABLE FOR ES-1.2 Step 8 STEP: Initiate RCS Cooldown To Cold Shutdown PURPOSE: To begin or continue a controlled RCS cooldown to cold shutdown temperature using a preferred or alternate method with a specified maximum cooldown rate BASIS:

The objective of a controlled cooldown is to reduce the overall temperature of the RCS coolant and metal to reduce the need for supporting plant systems and equipment required for heat removal. The maximum cooldown rate of 100°F/hr will preclude violation of the Integrity Status Tree thermal shock limits.

The preferred steam release path is to the condenser to conserve inventory; however, atmospheric release is the stated alternative. If RCS temperature and pressure are below certain limits, the RHR System may be in service and should be used to cool down the RCS to cold shutdown.

ACTIONS:

o Determine if RHR System is in service o Initiate RCS cooldown to cold shutdown o Maintain RCS cooldown rate in RCS cold legs less than 100°F/hr o Use RHR System o Dump steam to the condenser using normal steam dump system o Dump steam to the atmosphere using SG PORVs INSTRUMENTATION:

o RCS hot leg temperatures indication o RCS cold leg temperatures indication o Steam dump valves to condenser position indication o SG PORVs position indication o Plant specific RHR System instrumentation which includes valve position and pump status indication CONTROL/EQUIPMENT:

o Steam dump valves to condenser switches o SG PORVs switches o Plant specific RHR System controls which include valve and pump control s ES-1.2 Background 81 HP-Rev. 2, 4/30/2005 HES12BG.doc

2011 HNP RO NRC Written Exam

26. Given the following plant conditions:

- At 0530, RCS temperature was being maintained at 557°F with the plant in Mode 3 when a Small Break LOCA occurred

- At 0545, RCS temperature is 550°F

- The crew is ready to commence a cooldown to cold shutdown lAW EPP-009, Post LOCA Cooldown and Depressurization Which ONE of the following identifies (1) the lowest allowable temperature of the RCS at 0630 if the crew begins the MAXIMUM permissible cooldown rate AND (2) the basis for this temperature limit?

A (1)457°F (2) to ensure that Tech Spec cooldown limits are NOT exceeded B. (1)457°F (2) to ensure that a transition is NOT required to be made to FRP-P.1, Response to Imminent Pressurized Thermal Shock C. (1)450°F (2) to ensure that Tech Spec cooldown limits are NOT exceeded D. (1)450°F (2) to ensure that a transition is NOT required to be made to FRP-P.1, Response to Imminent Pressurized Thermal Shock 68

2O11HNPRO NRC Written Exam -

Feedback Plausibility and Answer Analysis In determining the RCS cooldown rate, the cold leg temperature change over the last 60 minutes must always be considered to ensure TS limits are not exceeded so the lowest temperature at 0630 with a 100°F CD will be 457°F.

A. Correct B. Incorrect Plausible since the lowest allowed temperature is 457°F, but it is to ensure TS limits are not exceeded.

C. Incorrect Plausible since if a cooldown rate of 100°F per hour over 45 minutes is performed 450°F will be the resulting temperature, but the cold leg temperature change over the last 60 minutes must always be considered to ensure TS limits are not exceeded.

D. Incorrect Plausible since if a cooldown rate of 100°F per hour over 45 minutes is performed 450°F will be the resulting temperature, but the cold leg temperature change over the last 60 minutes must always be considered to ensure TS limits are not exceeded.

69

2011 HNP RO NRC Written Exam Notes BW/E08; W/E03 LOCA Cooldown - Depress. /4 WEO3EG2.1 .32 Ability to explain and apply system limits and precautions.

(CFR: 41.10 / 43.2 / 45.12)

Importance Rating: 3.8 4.0 Technical

Reference:

EOP Users Guide, Rev. 30, Page 46; EPP-009 Step 10 Page 12 Rev. 18 References to be provided: None Learning Objective: EOP-LP-3.5 Objective 4 Question Origin: CIT Dev Bank EOP-3.5-R5 Comments: None Tier/Group: TI G2 70

I-TNP Licensed Operator Written Exam question #48 Post Exam Comment Comment for question 48 is that it should be deleted from the exam. The question was unclear as to what power supply was reenergized. An assumption could be made that it was the output of the charger which is correct or the input to the chargers from the motor control centers that are reenergized by the Emergency Diesel Generators following a loss of off-site power. In addition, the stem of the question is worded such that if the correct answer, a single charger, is selected the question is not grammatically correct. The use of lose vice lose(s) in the stem would require the correct answer to be plural to be grammatically correct. The lack of clarity and the grammatical incorrectness of the stem lead to confusion among the applicants.

Attached:

HNP Written Exam question #48 OP-i 56.01 Rev 31 Attachment I DC Electrical System Checklist

2O11HNPRONRCWr1ttenExarn

48. Given the following:

- The unit is operating at 100% power

- A Fire in Aux Bus IEI occurs, resulting in the loss of Aux Bus E Which ONE of the following describes the battery charger(s) that temporarily lose power and will automatically be re-energized?

A. IA-SA and 1 B-SA B. IA-SBand lB-SB C. 1A-SAorIB-SA D. 1A-SBorIB-SB 48

AttaQhment.1 - D E1etricaL Systeni Checklist Sheet 10 of 14 COMPONENT COMPONENT DESCRIPTION NUMBER POSITION CHECK VERIFY RAB 286 (continued)

MCC 1B21-SB 1 B21-SB-1CR Batt Chgr lA-SB 125 Volt ON MCC 1B31-SB 1 B31-SB-3CL Batt Chgr lB-SB 125 Volt ON PP-1E213 1E213-23 1 B-SB Battery Cell Charger ON PP-I B21 1-SB PP-I B21 1-SB-I 3 Supply to DP-1 B-SB Transducer ON IEE-531 B Train Battery Chargers Transfer Panel 1 EE-E536 MTS-1 N EUTRAL I EE-E537 MTS-2 NORMAL IB2I-SB SUPPLY TO IA-SB 1 EE-E538 MTS-3 NORMAL IB3I-SB SUPPLY TO lB-SB Batteri Charger IA-SB N/A AC Input ON/OFF*

N/A DC Output ON/OFF*

N/A Normal/Equalize NORMAL Battery Charger 1 B-SB N/A AC Input ON/OFF*

N/A DC Output ON/OFF*

N/A Normal/Equalize NORMAL

• These breakers may be ON or OFF due to the alternating operations of chargers. Circle correct position.

OP-i 56.01 Rev. 31 Page 105 of 113

2Q11 hNP RQNRQWrittnExm

48. Given the following:

- The unit is operating at 100% power

- A Fire in Aux Bus I El occurs, resulting in the loss of Aux Bus E Which ONE of the following describes the battery charger(s) that temporarily lose power and will automatically be re-energized?

A. 1 A-SA and 1 B-SA B. lA-SB and lB-SB C. IA-SAorIB-SA D lA-SB or lB-SB Feedback Plausibility and Answer Analysis Item directly evaluates a loss of AC power to the DC distribution system by evaluating the knowledge of the power supply to the safety rated batteiy chargers. The safety rated battery chargers are powered from seperate 480v MCCs off of each 6.9kv safety bus. A-SA and B-SB 6.9kv safety busses are supplied from Aux busses D and E, respectively. A loss of Aux bus E will result in a loss of the B-SB safety bus until it is re-energized by its EDG.

A. Incorrect. Plausible because the loss of Aux bus E will cause a loss of a safety bus but will ONLY result in the loss of B-SB safety battery chargers which does not include the IA-SA battery charger.

B. Incorrect. Plausible because the loss of Aux bus E will cause a loss of a safety bus but will ONLY result in the loss of B-SB safety battery chargers which does not include the IA-SB battery charger.

C. Incorrect. Plausible because the loss of Aux bus E will cause a loss of a safety bus but will ONLY result in the loss of B-SB safety battery chargers which does not include the IA-SA battery charger.

D. Correct.

122

2011 HNP RO NRC Written Exam Notes 062 A.C. Electrical Distribution 062K3.03 Knowledge of the effect that a loss or malfunction of the ac distribution system will have on the following: DC system (CFR: 41.7 /45.6)

Importance Rating: 3.1 4.2 Technical

Reference:

OP-i 56.01, Rev. 31, Page 101, 105, 107 References to be provided: None Learning Objective: DC Power Objective 9 Question Origin: 2008 North Anna Bank Comments: None Tier/Group: T2G1 123

HNP Licensed Operator Written Exam question #49 Post Exam Comment Comment for question #49 is both answers A and B are correct because insufficient information is provided in the stem of the question to determine when the DC load shed occurs.

The assumption was made that the stem of the question was asking the operator to determine the effect on safety battery life as our station procedures are implemented. In accordance with site procedures and the Station Blackout Coping Analysis, our 125VDC Class 1E batteries are rated to last for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> at rated load (CaIc 8S44-P-1 01 STATION BLACKOUT COPING ANALYSIS REPORT section 7.2.2.1) and the DC load shed occurs within 60 minutes following the loss of AC power (EOP-EPP-001 LOSS OF AC POWER TO 1A-SA AND I B-SB BUSES).lf the DC load shed to half rated load occurs instantaneously (concurrent with the loss of AC power), battery life would extend to greater than twice rated life, which would make A correct. If the DC load shed to half rated capacity occurs at time +60 minutes (as assumed in Calculation E4-0006 SAFETY BATTERIES IA-SA & lB-SB LOAD PROFILE DETERMINATION (LOCAISBO) section 4.2.2.4), then 25% of battery capacity would be used prior to loads being reduced to 50%. This would leave 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> of rated capacity life remaining. Following the load shed, this would extend remaining battery life to greater than 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Battery life cannot be greater than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> because of the 60 minutes at rated capacity already used. Therefore, answer B would be correct.

Attached:

HNP Written Exam question #49 Calculation E4-0006 Rev 2 page 6 8S44-P-101 Rev 8 page 7-5 thru 7-7

- 2011 HNP R0NRç WrittenExam.

49. Given the following plant conditions:

- A loss of AC power has occurred

- 125 VDC battery 1A-SA is currently loaded at rated load DC load shedding has been performed to reduce the battery load to half of rated load.

How long will the battery be available to supply the remaining loads?

A. More than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> B. More than 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> but less than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> C. More than 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> but less than 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> D. upto4hours 49

CALCULATION E4-000$

PAGE 6, REV. 2 4.2.1 .8 Include a summary of the equipment loading for each DC circuit during each of the significant load periods as Attachments D, G, J & M.

4.2.2 Assumptions 4.2.2. 1 With the exception of the indicating lights used in the Sequencer operation and the Transfer and Auxiliary Transfer Panels, which were conservatively analyzed, all non-green indicating lights are assumed to be on. Furthermore, lights associated with MOVs will have both red and green indicating lights energized.

4.2.2.2 Control room evacuation will not occur concurrent with a LOCA or SBO; therefore, relays required to permit transfer of controls from the main control board to the auxiliary control room are not considered.

4.2.2.3 During an SBO, in accordance with Table 1 of Reference 2.14, all three (3) flow isolation valves fed from DP-1A2-SA (AF-VI 16SAB-l, AF-VI I7SA-l AND AF-Vi I8SA-I) are normally in their required coping position (open), upon loss of AC power, and are not assumed to operate. Therefore, this loading has been deleted from the circuit 6 first minute SBO load profile.

4.2.2.4 During an SBO event, Reference 2.13 directs that both ESS panels feeder breakers (circuit no. 8 on 125V DC panels DP-1A-SA and DP-IB-SB) be manually opened. This analysis conservatively assumes that they are opened at 60 minutes after the initiation of the SBO event.

4.2.2.5 During an SBO event, Reference 2.13, directs that circuits 10, 11, 12 and 18 on both panels DP-IA-SA and DP-lB-SB be opened. This analysis conservatively assumes that they are opened at 60 minutes after the initiation of the SBO event.

4.2.2.6 For conservatism, during an SBO event, the diesel generator field winding will be flashed during both the entire first and last minute of the battery load profile.

4.2.2.7 6.9kV and 480V switchgear breaker spring charging motor inrush current will last for less than 1/2 second. However, the spring charging motor is conservatively made to operate at its inrush current for the subsequent time period after breaker operation which has a duration of typically more than 1/2 second. If the time period when the inrush current is occurring is longer than the running time of the spring charging motor, it is conservatively assumed that the motor current will he the inrush current for the entire time period. If the inrush current time period is shorter than the running time of the spring charging motor, the subsequent time period(s) after the spring charging begins, will utilize the steady state spring charging motor current until the sum of the inrush and steady state current time periods is equal to or greater than the spring charging motor running time.

4.2.2.8 Random Loads

a. The breakers for IA I XFMR and I B I XFMR are not required since they

8S44-P-l0l Revision 8 Page 7-5 Loss of normal seal injection coupled with loss of CCW seal cooling during a SBO will result in RCP seal failure and consequent RCS leakage of approximately 25 gpm per RCP. Additionally, without the availability of the ASI system, there is no means of reactor coolant inventory makeup during a SBO event. Though these factors are evaluated as acceptable as stated herein, they do significantly limit the ability of the plant to cope with a SBO condition.

The Quality Class B (SBO) Alternate Seal Injection and Dedicated Shutdown Diesel Generator (DSDG) systems installed by EC 70350 provide a diverse and redundant means of providing RCP seal cooling and reactor coolant makeup during a SBO event. This significantly improves the ability of HNP to maintain RCS cooling and RCS inventory control safety functions during a SBO event. Though the leakage conditions and scenario conclusions made in NUIvIARC 87-00 and herein will remain as the bounding criteria for Reactor Coolant Inventory Loss, the defense in depth enhancement provided by the ASI and DSDG are credited with significantly improving the capabilities of HNP to cope with a SBO event.

7.2.2 Battery Capacity 7.2.2.1 Summary The capacity of the RNP 1 25VDC Class 1 E batteries to support decay heat removal during a station blackout for the four hour coping duration was checked by calculation E4-0008 [Reference 9.4.2]. It was concluded that the two Class IE battery systems have adequate capacity, with a 10% design margin, to power the coping loads with load stripping within the first 60 minutes of SBO. Attachment 3 of EOP-EPP-OOl [Reference 9.3.1.1] presents the load shed list.

The capacity of the HNP 125VDC non-Class IE battery to support a station blackout for the four hour coping duration was checked by calculations E4-0009 and E4-00l0

[References 9.4.3 and 9.4.4]. It was concluded that the 125 VDC non-Class IE battery has adequate capacity, with an 8% design margin, to power the coping loads with load stripping within the first 60 minutes of SBO. Attachment 3 of EOP-EPP 001 [Reference 9.3.1.1] presents the load shed list.

8S44-P-l0l Revision 8 Page 7-6 7.2.2.2 Class IE Batteries Progress Energy (formerly CP&L) Battery Calculation E4-0008, ]25VDCBatteiy Sizing and Battety/Panel Voltages/br Station Blackout [Reference 9,4.2], utilizes the methodology contained in IEEE-STD-485, Recommended Practice/or Sizing Large Lead Storage Batteries/br Generating Stations and Substations [Reference 9.1.3.1].

This calculation was used as the basis of the SBO Class IE battery capacity check.

Following the practice used in TEEE-485, an aging factor of 1 .25 was used to account for the drop in battery capacity at end of life. A temperature factor of 1.04 was used to check the battery for a worst case operating temperature of 70°F. HNP Operations Surveillance Test Procedure OST-l02l [Reference 9.3.3.9] provides assurance that the battery room temperature is maintained at or above 70°F.

The calculation used a design margin factor of 1.10 (i.e, 10%). Justification for use of this design margin was presented to the NRC in References 9.2.5 and 9.2.6. The calculation concluded that both HNP Class 1E battery systems have adequate capacity, with load stripping within the first 60 minutes of SBO, to meet the requirements of the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> coping period.

The NRC SBO SSER [Reference 9.1 .2.8] stated that a 10% design margin is required to compensate for less than optimum operating conditions, recent discharge, accuracy in identifying all small DC loads (indicating lights, relays, solenoids, etc.)

and the inaccuracy in reading the discharge curve. Progress Energy (formerly CP&L) committed in Reference 9.2.6 that the Class lE battery design margin for SBO will not be less than 10%.

EC 70350 installs a Quality Class B (SBO) alternate power feed to power the Safety Related battery chargers. This alternate feed is supplied from MCC 1 D23 which is supplied from normal feed bus lD2-7B or its alternate feed from the DSDG which is completely independent of the plant AC Distribution System or other plant support systems. Though the availability of these alternate charger feeds will not alter the 4-hour coping duration as demonstrated in Calculation E4-0008, 125VDC IE Battery Sizing and Battery/Panel Voltages For Station Blackout (Reference 9.4.2), the defense in depth enhancement they provide significantly improves the capabilities of 1-TNP to cope with a SBO event.

8S44-P-10l Revision 8 Page 7-7 7.2.2.3 Non-Class 1E Batteries Certain equipment listed in Table 1, that is required for coping, draw power from the non-Class 1E 125 VDC battery. The non-Class 1E battery calculations utilized the methodology contained in IEEE-STD-485. Progress Energy (formerly CP&L) has not made a commitment to provide a 10% design margin in the non-Class 1 E batteries. Progress Energy (formerly CP&L) maintains that a 0% design margin for non-Class 1E batteries is adequate for SBO.

Calculations E4-0009, 125 VDCNon-lEBatteiy Load Data andDuty Cycle

[Reference 9.4.3] and E4-00l0, 125 VDCNon-lEBattery Sizing andBatteiy/Panel Voltages [Reference 9.4.4] were used as the basis of the SBO non-Class IE I 25VDC battery check. The calculations used an aging factor of 1.25 to account for the drop in battery capacity at end of life, a temperature factor of 1.04 to check the battery for a worst case operating temperature of 70°F and a design margin factor of 1.08 (i.e, 8%). The calculation concluded that the 1 25VDC non-Class 1 E battery has adequate capacity, with load stripping within the first 60 minutes of SBO, to meet the requirements of the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> coping period.

7.2.2.4 Strippable Loads NUMARC 87-00, Section 4.2.1(6) requires that plant procedures should identify individual loads that need to be shed from the plant DC buses (both Class 1 E and non-Class 1E) for the purpose of conserving DC power. The 125 VDC battery calculations [References 9.4.2, 9.4.3, and 9.4.4] indicate that load stripping of the 125 VDC safety and non-safety battery loads are required during SBO. EOP-EPP 001 [Reference 9.3.1.1] identifies the loads required to be stripped and the load stripping sequence (i.e., loads required to be stripped within the first 60, and 90 minutes of SBO).

7.2.3 Compressed Air 7.2.3.1 Summary There are no requirements for compressed air to assure containment isolation or to cope with SBO.

20t1 HNP.RQNRCWrittanExaru.

49. Given the following plant conditions:

- A loss of AC power has occurred

- 125 VDC battery 1A-SA is currently loaded at rated load DC load shedding has been performed to reduce the battery load to half of rated load.

How long will the battery be available to supply the remaining loads?

Ab. More than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> B. More than 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> but less than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> C. More than 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> but less than 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> D. upto4hours Feedback Plausibility and Answer Analysis Reducing the discharge rate on a battety increases the batteiy capacity in a non-linear function such that decreasing the discharge rate by halI increases the capacity by more than double.

A. Correct.

B. Incorrect. Plausible since the discharge rate has been halved, so it would appear that the capacity would be doubled, but it is a non-linear relationship.

C. Incorrect. Plausible since the discharge rate has been halved, so it would appear that the capacity would be doubled, but it is a non-linear relationship.

D. Incorrect. Plausible since the battery is rated for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, but at a discharge halving the discharge rate would increase the capacity.

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2011 HNP EQ NRC Wrilten Exam Notes 063 DC Electrical Distribution 063A1 .OlAbility to predict and/or monitor changes in parameters associated with operating the DC electrical system controls including: Battery capacity as it is affected by discharge rate (CFR: 41.5 / 45.5)

Importance Rating: 2.5 3.3 Technical

Reference:

GFES No Reference supplied References to be provided: None Learning Objective: DC Power Objective 8 Question Origin: Bank OIT Exam Bank DCP (02A) 1 Comments: None Tier/Group: T2GI 125