ML18074A310

Request for Additional Information License Amendment Request for Addition of New Technical Specification 3.7.20, Class 1E Electrical Equipment Air Conditioning System (CAC No. MF9961; EPID L-2017-LLA-0262)

ML18074A310
Person / Time
Site:	Wolf Creek
Issue date:	04/06/2018
From:	Balwant Singal Plant Licensing Branch IV
To:	Heflin A Wolf Creek
Singal B, NRR/DORL, 301-415-3016
References
EPID L-2017-LLA-0262
Download: ML18074A310 (13)

Text

Mr. Adam C. Heflin UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 April 6, 2018 President, Chief Executive Officer, and Chief Nuclear Officer Wolf Creek Nuclear Operating Corporation Post Office Box 411 Burlington, KS 66839

SUBJECT:

WOLF CREEK GENERATING STATION, UNIT 1 - REQUEST FOR ADDITIONAL INFORMATION RE: LICENSE AMENDMENT REQUEST FOR ADDITION OF NEW TECHNICAL SPECIFICATION 3.7.20, "CLASS 1E ELECTRICAL EQUIPMENT AIR CONDITIONING (A/C) SYSTEM" (CAC NO. MF9961; EPID L-2017-LLA-0262)

Dear Mr. Heflin:

By letter dated June 28, 2017 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML17186A082), as supplemented by letter dated February 15, 2018 (ADAMS Accession No. ML18058A743), Wolf Creek Nuclear Operating Corporation (the licensee), submitted a license amendment request (LAR) for Wolf Creek Generating Station, Unit 1 (WCGS). The proposed amendment would incorporate new Technical Specification (TS) 3. 7.20, "Class 1 E Electrical Equipment Air Conditioning (A/C) System."

New TS 3.7.20 will include the Limiting Condition for Operation (LCO) statement, Applicability during which the LCO must be met, ACTIONS (with Conditions, Required Actions, and Completion Times) to be applied when the LCO is not met, and surveillance requirements (with a specified Frequency) to demonstrate that the LCO is met for the Class 1 E electrical equipment A/C trains at WCGS.

The U.S. Nuclear Regulatory Commission (NRC) staff conducted a regulatory audit at the WCGS site from November 7 to 8, 2017. The NRC staff had a number of conference calls with the licensee following the audit to discuss the open items discussed during the audit. The NRC staff has identified the need for additional information described in the Enclosure to this letter for completing the review of the LAR. Since the request for additional information (RAI) was discussed with the licensee during multiple conference calls following the audit, there is no need to issue draft RAls in order to provide an opportunity for a clarification call. The licensee is requested to provide a response to the RAls within 30 days from the date of this letter.

If you have any questions, please contact me at 301-415-3016 or via e-mail at Balwant.Singal@nrc.gov.

Docket No. 50-482 Enclosure Request for Additional Information cc: Listserv Sincerely,

~"it-&~~

Balwant K. Singal, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST FOR ADDITION OF NEW TECHNICAL SPECIFICATION 3.7.20 WOLF CREEK NUCLEAR OPERATING CORPORATION WOLF CREEK GENERATING STATION, UNIT 1 DOCKET NO. 50-482 By letter dated June 28, 2017 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML17186A082), as supplemented by letter dated February 15, 2018 (ADAMS Accession No. ML18058A743), Wolf Creek Nuclear Operating Corporation (WCNOC, the licensee), submitted a license amendment request {LAR) for Wolf Creek Generating Station, Unit 1 (WCGS). The proposed amendment would incorporate new Technical Specification

{TS) 3.7.20, "Class 1 E Electrical Equipment Air Conditioning (NC) System."

New TS 3.7.20 will include the Limiting Condition for Operation (LCO) statement, Applicability.

during which the LCO must be met, ACTIONS (with Conditions, Required Actions, and Completion Times (CTs)) to be applied when the LCO is not met, and surveillance requirements (SRs) (with a specified Frequency) to demonstrate that the LCO is met for the Class 1 E electrical equipment NC trains at WCGS.

The U.S. Nuclear Regulatory Commission (NRC) staff conducted a regulatory audit at the WCGS site from November 7 to 8, 2017. The NRC staff had a number of conference calls with the licensee following the audit to discuss the open items discussed during the audit. The NRC staff has identified the need for additional information described in the Enclosure to this letter for completing the review of the LAR. Since the request for additional information (RAI) was discussed with the licensee during multiple conference calls following the audit, there is no need to issue draft RAls in order to provide an opportunity for a clarification call.

Please note that the RAI represents input from the following technical review branches:

Containment and Plant Systems Branch (SCPB)

Probabilistic Risk Assessment Operations & Human Factors Branch (APHB)

Electrical Engineering Operating Reactor Branch (EEOB)

SCPB RAls Regulatory Basis The main purpose of the proposed amendment is to allow an inoperable Class 1 E electrical equipment NC train to be restored to OPERABLE status within 30 days. The 30-day CT is based on the capability of the remaining OPERABLE Class 1 E electrical equipment NC train to provide adequate area cooling for both trains of electrical equipment during normal and accident conditions.

Enclosure Paragraph 50.36(c)(2)(i) of Title 10 of the Code of Federal Regulations (10 CFR) describes a TS LCO as the lowest functional capability or performance levels of equipment required for the safe operation of the facility. Criterion 3 of 10 CFR 50.36(c)(2)(ii) requires that TSs contain LCOs for

"[a] structure, system, or component that is part of the primary success path and which functions or actuates to mitigate a design basis accident or transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier."

The licensee has determined that despite the fact that the Class 1 E Electrical Equipment A/C System was not included in the original WCGS TSs for initial plant licensing, an LCO is needed for the system because of specific operational hardships presented in the LAR with short CTs associated with supported systems such that the provisions of LCO 3.0.6 may apply. Per LCO 3.0.6, only the support system LCO ACTIONS are required to be entered.

Section 2.102(a) of 10 CFR states, in part, that "[d]uring review of an application by the NRC staff, an applicant may be required to supply additional information." The following RAI is necessary for the NRC staff to clearly understand the technical information provided by the licensee in its application and make a determination regarding adequate protection of public health and safety.

RAI SCPB-1 Attachment II of the letter dated June 28, 2018, states, in part:

During normal or emergency operations, each Class 1 E electrical equipment A/C train maintains the temperature in its associated electrical equipment rooms at a temperature of s [less than or equal to] 90 °F [degrees Fahrenheit]. The Class 1 E electrical equipment A/C trains are designed in accordance with Seismic Category I requirements.

Please describe the safety classification of the Class 1 E electrical equipment A/C train.

SCPB RAl-2 Attachment VI, "List of Regulatory Commitments," of the letter dated June 28, 2017, describes the proposed plant modifications including recirculation fans and associated dampers and LED lighting being implemented in support of the LAR for 2016 feet and 2000 feet levels.

Attachment I (page 6, Item 9), of the letter dated February 15, 2018, describes the planned modification in detail, including the number of safety-related fans; isolation dampers; fire dampers; transition grills; heating, ventilation, and air-conditioning (HVAC) ductwork; and power supplies and control cables. Also, the letter described the post modification testing. As a result, the regulatory commitments specified in the letter dated June 28, 2017, are not consistent with the proposed modification description provided in the letter dated February 15, 2018.

a.

Please revise the regulatory commitments specified in the letter dated June 28, 2017, to be consistent with the proposed modification description provided in the letter dated February 15, 2018. Regulatory commitments incorporated in the description of the LAR may be removed.

b.

Please provide a copy of the Piping and Instrumentation Diagram for the Control Building (HVAC) system for the NRC staff to fully understand the proposed planned modification described in the application.

SCPB RAl-3 Attachment II (page 3) of the letter dated June 28, 2017, states, in part:

The Class 1 E electrical equipment A/C trains provide a suitable environment for the Class 1 E electrical equipment.

Attachment V, "Proposed TS Bases Changes," of the letter dated June 28, 2017, states, in part, the following for SR 3.7.20.2 Bases:

Testing of the Class 1 E Electrical Equipment Air Conditioning (A/C) System condenser heat exchangers under design conditions is impractical. This SR verifies that the heat removal capability of the air conditioning units is adequate to remove the heat load assumed in the control room during design basis accidents. This SR consists of verifying the heat removal capability of the condenser heat exchanger (either through performance testing or inspection),

ensuring the proper operation of major components in the refrigeration cycle, verification of unit air flow capacity, and water flow measurement....

The bases for SR 3.7.20.2 state that this SR verifies that the heat removal capability of the A/C units is adequate to remove the heat load assumed in the control room during design basis accidents. Please clarify if the intent was to state that this SR verifies that the heat removal capability of the A/C units is adequate to remove the heat load assumed in the Class 1 E Electrical area during design basis accidents.

SCPB-RAl-4 Attachment I (page 7, Item 17), of the letter dated February 15, 2018, the licensee has proposed to develop a new technical requirements manual (TRM) specification associated with the recirculation subsystem and include associated SRs in the TRM.

Please provide description of the proposed TRM.

APHB RAls Regulatory Basis The NRC staff reviews the human performance aspects of LARs utilizing the review guidance in NUREG-0800, "Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR [Light-Water Reactor] Edition," Section 18, Revision 3, "Human Factor Engineering" (ADAMS Accession No. ML16125A114), and NUREG-1764, Revision 1, "Guidance for the Review of Changes to Human Actions" (ADAMS Accession No. ML072640413).

NUREG-1764, Appendix A, Table A.2, "Generic PWR [Pressurized-Water Reactor] Human Actions That Are Risk-Important," lists human actions associated with the recovery of emergency alternating current (AC) or offsite power as potentially risk-important. The proposed addition of TS 3. 7.20 and the planned modifications will enable redundant trains of Class 1 AC electrical systems to remain Operable while the support system for one train is Inoperable.

The proposed changes involve human actions that mitigate equipment inoperability (Class 1 AC cooling system) that would result in the loss of a train of emergency Class 1 AC power.

Further, the proposed human actions in combination with the planned modifications breach the train separation barrier to allow the support system of the redundant train to cool components for both trains. However, the associated human actions are not complicated or involve preexisting, proceduralized actions. Therefore, the NRC staff has determined that the subject LAR will receive a Level II human factors review, per the guidance in Section 4 of NUREG-1764, Revision 1.

RAI APHB-1 The licensee's letter dated June 28, 2017, includes information regarding potential cross-train impacts related to fire protection, hydrogen gas buildup. The NRC staff is evaluating if the proposed operator action creates a condition that adversely impacts plant system independence, redundancy, or separation. Please provide or summarize evaluations that addresses maintaining train independence, redundancy, and separation when opening a communication pathway between the Operable and Inoperable redundant trains for any other applicable hazard or condition such as, flooding or any requirements to maintain negative pressure in the affected areas for HVAC/radiological control issues (Reference NUREG-1764, Section 4, "Level II Review Guidance").

RAI APHB-2 The NRC staff is evaluating the proposed compensatory actions that will support the operability temperature limit of s 90 °F and the GOTHIC model assumption that mitigating actions are completed within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> as described in Attachment II, Section 3.4, of the letter dated June 28, 2017. Please describe the validation completed to confirm that the various ways, described on page 12 of 48 of Attachment 11 of the letter dated June 28, 2017, that an A/C train failure can be identified in enough time to allow 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to implement the mitigating actions before the rooms reach 90 °F.

RAI APHB-3 Please describe the following so that the NRC staff can evaluate the effectiveness of the manual operator actions:

a.

The procedures/administrative controls used to direct, and the operator actions to place the switchgear room recirculation fans in service.

b.

Procedures used to de-energize NK021/NK024 battery chargers and transfer charging of Class I batteries to battery chargers NK025/NK026.

c.

The validation completed to confirm that all required actions listed in Attachment II, Section 3.4, of letter dated June 28, 2017, can be completed in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> once TS 3. 7.20, Action A.1 is entered.

d.

The procedures used to secure one train of the Control Building Pressurization System (CBPS) Post-Loss-of-Coolant Accident (LOCA).

e.

The validation completed to confirm that all human actions required to secure one train of the CBPS Post-LOCA within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> can be accomplished.

f.

The procedure controls for any applicable human actions that are not listed in Attachment II, Section 3.4, of the letter dated June 28, 2017, such as the establishment of temperature monitoring.

g.

The validation completed for any applicable human actions that are not listed in Attachment II, Section 3.4, of the letter dated June 28, 2017, such as the establishment of temperature monitoring.

h.

The planned training to operating personnel regarding the operation of the new recirculating fans, and implementation of the compensatory actions described in Attachment II, Section 3.4, of the letter dated June 28, 2017.

i.

The administrative controls that alert control room operators during Normal Operations of the need to initiate mitigating actions to start the switchgear room recirculation fans within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.

j.

The administrative controls that alert control room operators during post-LOCA conditions of the need to secure one train of CBPS pressurization fans within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> if the switchgear room recirculation fans are operating.

EEOB RAls Regulatory Basis The design basis of the Class 1 E Electrical Equipment A/C System at WCGS is to maintain temperature in the Class 1 E electrical equipment rooms to assure operability of associated electrical equipment. The proposed LAR is related to TS changes that will be implemented to support plant operation for limited duration with one train of A/C system available for redundant trains of electrical equipment. The regulatory basis are related to AC and direct current (DC) equipment in the areas impacted by the A/C system.

The regulation at 10 CFR 50.36(a)(1), requires an applicant for an operating license to include in the application proposed TSs in accordance with the requirements of 10 CFR 50.36. As required by 10 CFR 50.36(c), technical specifications will include safety limits, limiting safety system settings, and limiting control settings. Paragraph 50.36(a)(1)(i)(A) of 10 CFR states, in part:

Safety limits for nuclear reactors are limits upon important process variables that are found to be necessary to reasonably protect the integrity of certain of the physical barriers that guard against the uncontrolled release of radioactivity. If any safety limit is exceeded, the reactor must be shut down. The licensee shall notify the Commission, review the matter, and record the results of the review, including the cause of the condition and the basis for corrective action taken to preclude recurrence. Operation must not be resumed until authorized by the Commission.

Also, as stated in WCGS Updated Safety Analysis Report (USAR), Section 3.1, the requirements of the following 1 O CFR Part 50, Appendix A, "General Design Criteria for Nuclear Power Plants," also apply to the Class 1 E Electrical Equipment A/C System:

Criterion 13, "Instrumentation and control" (GDC 13), of 10 CFR Part 50, Appendix A, states:

Instrumentation shall be provided to monitor variables and systems over their anticipated ranges for normal operation, for anticipated operational occurrences, and for accident conditions as appropriate to assure adequate safety, including those variables and systems that can affect the fission process, the integrity of the reactor core, the reactor coolant pressure boundary, and the containment and its associated systems. Appropriate controls shall be provided to maintain these variables and systems within prescribed operating ranges.

Criterion 17, "Electrical power systems" (GDC 17), of 1 O CFR Part 50, Appendix A, states, in part:

An onsite electric power system and an offsite electric power system shall be provided to permit the functioning of structures, systems, and components important to safety. The safety function for each system (assuming the other system is not functioning) shall be to provide sufficient capacity and capability to assure that ( 1) specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated operational occurrences and (2) the core is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents.

The NRC staff is requesting the following additional information based on the review of the LAR.

RAI EEOB-1 Applicable Regulations: GDCs 13 and 17 The licensee is implementing plant modifications to maintain the environment for operability of onsite and offsite power systems required for conformance with GDC 17. The licensee is installing instrumentation to monitor variables and systems over their anticipated ranges (to maintain the variables and systems within prescribed operating ranges) in accordance with GDC 13. In the LAR, the licensee has discussed the proposed temperature range for the GDC 17 required power sources. The NRC staff is requesting additional information on events and accidents considered for instrumentation needed during anticipated ranges for room temperatures during normal operation, for anticipated operational occurrences, and for accident conditions.

Section 3.2.2 "Inputs/Assumptions" of the letter dated June 28, 2017, references GK-E-001, Revision 4, "Electrical Equipment Heat Loads in ESF [Engineered Safety Features] SWGR

[Switchgear], DC SWBD [Switchboard] and Battery Rooms." This calculation was used to determine heat loads due to electrical equipment in ESF SWGR Rooms, DC SWBD Rooms, and Battery Rooms during Normal operation (Mode 1 with off-site power available), LOCA condition, station blackout condition, and one HVAC operating during the post-LOCA condition.

The electrical heat loads identified in this calculation support the Class 1 E HVAC calculations as described in the LAR. Section 3.2.2 also states, in part, "[i]t is noted that in many safety analysis calculations, a loss of offsite power (LOOP) is assumed to occur. USAR Section 15.6.5.3.2 specifically states that "for the small break LOCA (SBLOCA), LOOP is assumed, which results in the limiting single failure assumption of the loss of one diesel generator (DG) and a subsequent loss of one train of pumped Emergency Core Cooling System (ECCS)."

The NRC staff is reviewing the combinations of events and plant conditions that were considered for heat load calculations. Please provide a discussion on the plant conditions and corresponding source of power. Please include in your discussion whether the accident condition(s) considered in the evaluations assume a concurrent LOOP or an accident/event with offsite power available and also provide details on any postulated failures. Please include a copy of the current revision of the calculation GK-E-001, Revision 4, referenced in the LAR.

RAI EEOB-2 Applicable Regulations: GDCs 13 and 17 The licensee is implementing plant modifications to maintain the environment for operability of onsite and offsite power systems required for conformance with GDC 17. The licensee is installing instrumentation to monitor variables and systems over their anticipated ranges (to maintain the variables and systems within prescribed operating ranges) in accordance with GDC 13. In the LAR, the licensee has discussed the proposed temperature range for the GDC 17 required power sources. The NRC staff is requesting additional information on parameters that were considered for instrumentation needed during anticipated ranges of room temperatures for normal operation, for anticipated operational occurrences, and for accident conditions.

WCGS has a large number of motor loads which are operating during normal operation and accident conditions. These motors draw a higher load current as the voltage drops at the motor terminals. The voltage drop in the plant distribution system will increase after a main generator trip. The loss of generation from the main generator will also result in switchyard voltage to drop to a value below nominal and can be as low as 95-97 percent of nominal. Electrical calculations make assumptions related to system voltage, conductor temperatures, diversity factors, raceway fills, etc. Assumptions and input criteria for heat load calculation should correspond to the assumptions and input criteria used in calculations developed for AC system analyses.

The NRC staff is seeking the following information on input criteria used in the calculations.

a.

With offsite power at minimum voltage for normal operation or postulated accident conditions, please provide a discussion comparing the voltage drop and associated load current for room heat calculations discussed in the LAR with voltage and current values developed in corresponding AC system loadflow and voltage drop analysis.

b.

Please provide a discussion comparing the magnitude of loads considered in WCGS calculation(s) developed for heat load evaluations with the bus loads assumed in calculations developed for AC system analyses for normal and accident conditions.

c.

Please provide a discussion comparing the actual tray fill for raceways associated with ECCS power cables with percentage fill assumed in the heat load calculation. In areas where cables may be routed in conduits or other raceway systems, provide a discussion of the actual loading criteria used.

d.

Please provide a discussion related to the change in heat load calculations described in the LAR assuming the temperature of the current carrying conductors is 90 degrees Centigrade (design limit) at steady state conditions.

e.

Please provide a discussion on any load diversity factor used in calculation of heat loads during accident conditions when majority of safety-related equipment is operating.

RAI EEOB-3 Applicable Regulations: GDCs 13 and 17 The licensee is implementing plant modifications to maintain the environment for operability of onsite and offsite power systems required for conformance with GDC 17. The licensee is installing instrumentation to monitor variables and systems over their anticipated ranges (to maintain the variables and systems within prescribed operating ranges) in accordance with GDC 13. In the LAR, the licensee has discussed the proposed temperature range for the GDC 17 required power sources. The NRC staff is requesting additional information on parameters that were considered for instrumentation needed during anticipated ranges of room temperatures for normal operation, for anticipated operational occurrences, and for accident conditions.

The NRC staff needs clarification on heat loads for normal operation and post-LOCA. Please provide a discussion on heat loss results when using just one HVAC unit during the post-LOCA for the following scenarios:

Train A Heat Loss Results with One HVAC Unit Operating post-LOCA.

Train B Heat Loss Results with One HVAC Unit Operating post-LOCA.

Please include a discussion on heat loads at T=O if accident mitigating equipment in Train A and Train B starts when an accident signal is actuated.

RAI EEOB-4 Applicable Regulations: 10 CFR 50.36, GDC 13 and 17, and related Licensing Basis described below:

1. Technical Specification 3.8.6, "Battery Cell Parameters," has SR 3.8.6.3, which states, "Verify average electrolyte temperature of representative cells is.!: [greater than or equal to] 60 ° F."

2. WCGS USAR, Section 9.4, "Air Conditioning, Heating, Cooling and Ventilation."

The licensee is implementing plant modifications to maintain the environment for operability of onsite and offsite power systems required for conformance with GDC 17. The licensee is installing instrumentation to monitor variables and systems over their anticipated ranges (to maintain the variables and systems within prescribed operating ranges) in accordance with GDC 13. In the LAR, the licensee has discussed the proposed upper limit for temperature for the GDC 17 required power sources. The LAR does not discuss the lower allowable temperature limit. The NRC staff is requesting additional information on parameters that were considered for instrumentation and actions needed for managing battery operability for normal operation, for anticipated operational occurrences, and for accident conditions when ambient conditions change.

USAR Section 9.4 provides details on control building ventilation design basis and states that periods of control building isolation can be maintained for approximately 3 days before purging is required to prevent local hydrogen concentration from approaching 2.0 volume percent.

USAR Section 1.2 states that the plant site experiences a wide seasonal range of temperatures

- maximum of 117° F and lowest temperature of -26° F. The ambient temperature in the battery rooms, under any mode of operation, is required to be maintained between 60° F and 90° F.

The LAR proposes plant operation for 30 days with one Class 1 E electrical equipment HVAC train supporting redundant electrical equipment areas. Section 3.4 "Operator Actions" of Attachment II of the letter dated June 28, 2017, states that calculation GK-E-001 takes credit for equipment that can be turned off within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and 7 days after initiation of a LOCA event.

Hence the load shedding will result in considerable reduction in heat input from electrical loads after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The LAR does not discuss the consequences on room temperatures when the site experiences low winter temperatures. Please provided a discussion that battery electrolyte temperatures will not drop below the design basis temperature of 60 °F for the duration of planned or unplanned HVAC system outage with prevailing winter conditions and any make up outside air required to maintain design basis conditions in the control building.

RAI EEOB-5 Applicable Regulations: GDCs 13 and 17 The licensee is implementing plant modifications to maintain the environment for operability of onsite and offsite power systems required for conformance with GDC 17. The licensee is installing instrumentation to monitor variables and systems over their anticipated ranges (to maintain the variables and systems within prescribed operating ranges) in accordance with GDC 13. In the LAR, the licensee has discussed the proposed temperature range for the GDC 17 required power sources. The NRC staff is requesting additional information on parameters that were considered for instrumentation needed during anticipated ranges of room temperatures to provide reasonable assurance that the onsite and offsite power systems provide sufficient capacity and capability to assure that ( 1) specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated operational occurrences and (2) the core is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents.

Section 3.2.2 "Inputs/Assumptions" of Attachment II of the letter dated June 28, 2017, discusses accidents analyses and various types of line breaks considered in Chapter 15 of the USAR.

Section 3.4 of Attachment II of letter dated June 28, 2017, states that calculation GK-E-001 takes credit for equipment that can be turned off within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and 7 days after initiation of a LOCA event. The evaluation assumes that significant safety-related operating loads can be shed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to reduce heat loads in the area. The evaluation also assumes that LOCA loads provide the bounding condition for heat generation. A large break LOCA condition may be bounding for magnitude of heat load considerations over a short duration. A small break, midsize break, or a steamline rupture may impose a lower heat load at the onset of an event but the duration of some large loads maybe more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> assumed in the heat load calculations.

a.

Please provide a discussion that the heat load calculation and associated load curtailment is bounding for all events considered in the safety analysis of WCGS.

b.

Please provide a discussion that plant procedures (normal operation and emergency operation) and accident analyses provide guidance and basis for load shedding.

SUBJECT:

WOLF CREEK GENERATING STATION, UNIT 1 - REQUEST FOR ADDITIONAL INFORMATION RE: LICENSE AMENDMENT REQUEST FOR ADDITION OF NEW TECHNICAL SPECIFICATION 3.7.20, "CLASS 1E ELECTRICAL EQUIPMENT AIR CONDITIONING (A/C) SYSTEM" (CAC NO. MF9961; EPID L-2017-LLA-0262) DATED APRIL 6, 2018 DISTRIBUTION:

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