ML19176A086

Issuance of Amendment No. 237 Changes to Containment Oxygen Concentration Requirements

ML19176A086
Person / Time
Site:	Nine Mile Point
Issue date:	07/30/2019
From:	Marshall M Plant Licensing Branch 1
To:	Bryan Hanson Exelon Generation Co, Exelon Nuclear
Marhsall M, NRR/DORL/LPL, 415-2871
References
EPID L-2018-LLA-0183
Download: ML19176A086 (17)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 July 30, 2019 Mr. Bryan C. Hanson Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

NINE MILE POINT NUCLEAR STATION, UNIT 1 - ISSUANCE OF AMENDMENT NO. 237 RE: CHANGES TO CONTAINMENT OXYGEN CONCENTRATION REQUIREMENTS (EPID L-2018-LLA-0183)

Dear Mr. Hanson:

The U.S. Nuclear Regulatory Commission (the Commission) has issued the enclosed Amendment No. 237 to Renewed Facility Operating License No. DPR-63 for the Nine Mile Point Nuclear Station, Unit 1. The amendment consists of changes to the Technical Specifications in response to your application dated June 26, 2018 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18177A044), as supplemented by letters dated February 25, 2019 (ADAMS Accession No. ML19056A387) and May 17, 2019 (ADAMS Accession No. ML19137A070).

The amendment revises Technical Specification 3.3.1, "Oxygen Concentration," to require inerting the primary containment to less than four percent by volume oxygen concentration within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of entering power operating condition. Also, the amendment adds a new requirement to identify required actions, if the primary containment oxygen concentration increases to greater than or equal to four volume percent while in the power operating condition.

B. Hanson A copy of the related Safety Evaluation is enclosed. Notice of issuance will be included in the Commission's next biweekly Federal Register notice.

Sincerely, Michael L. Marshall, Jr., Senior Project Manager Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-220

Enclosures:

1. Amendment No. 237 to DPR-63

2. Safety Evaluation cc: Listserv

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 EXELON GENERATION COMPANY, LLC NINE MILE POINT NUCLEAR STATION, LLC DOCKET NO. 50-220 NINE MILE POINT NUCLEAR STATION, UNIT 1 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 237 Renewed License No. DPR-63

1. The U.S. Nuclear Regulatory Commission (the Commission) has found that:

A. The application for amendment by Exelon Generation Company, LLC (Exelon, the licensee) dated June 26, 2018, as supplemented by letters dated February 25, 2019 and May 17, 2019, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act) and the

• Commission's rules and regulations set forth in 10 CFR Chapter I; B. The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C. There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations; D. The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E. The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.

Enclosure 1

2. Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 2.C.(2) of Renewed Facility Operating License No. DPR-63 is hereby amended to read as follows:

(2) Technical Specifications The Technical Specifications contained in Appendix A, which is attached hereto, as revised through Amendment No. 237, is hereby incorporated into this license. Exelon Generation shall operate the facility in accordance with the Technical Specifications.

3. This license amendment is effective as of the date of its issuance and shall be implemented within 60 days.

FOR THE NUCLEAR REGULATORY COMMISSION C)~~

James G. Danna, Chief Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the License and Technical Specifications Date of Issuance: .July 3 o, 2 o1 9

ATTACHMENT TO LICENSE AMENDMENT NO. 237 NINE MILE POINT NUCLEAR STATION, UNIT 1 RENEWED FACILITY OPERATING LICENSE NO. DPR-63 DOCKET NO. 50-220 Replace the following page of the Renewed Facility Operating License with the attached revised page. The revised page is identified by amendment number and contains marginal lines indicating the areas of change.

Remove Insert 3 3 Replace the following pages of Appendix A, Technical Specifications, with the attached revised pages. The revised pages are identified by amendment number and contain marginal lines indicating the areas of change.

Remove Insert 124 124 125 125

(1) Exelon Generation pursuant to the Act and 10 CFR Part 70, to receive, possess and use at any time special nuclear material as reactor fuel, in accordance with the limitations for storage and amounts required for reactor operation, as described in the Final Safety Analysis Report, as supplemented and amended; (2) Exelon Generation pursuant to the Act and 10 CFR Parts 30, 40, and 70 to receive, possess and use at any time any byproduct, source and special nuclear material as sealed neutron sources for reactor startup, sealed sources for reactor instrumentation and radiation monitoring equipment calibration, and as fission detectors in amounts as required; (4) Exelon Generation pursuant to the Act and 10 CFR Parts 30, 40 and 70, to receive, possess and use in amounts as required any byproduct, source or special nuclear material without restriction to chemical or physical form, for sample analysis or instrument and equipment calibration or associated with radioactive apparatus or components.

(5) Exelon Generation pursuant to the Act and 10 CFR Parts 30 and 70, to possess, but not separate, such byproduct and special nuclear materials as may be produced by the operation of the facility.

C. This renewed operating license shall be deemed to contain and is subject to the conditions specified in the following Commission regulations in 10 CFR Chapter I:

Part 20, Section 30.34 of Part 30; Section 40.41 of Part 40; Section 50.54 and 50.59 of Part 50; and Section 70.32 of Part 70. This renewed license is subject to all applicable provisions of the Act and to the rules, regulations, and orders of the Commission now or hereafter in effect and is also subject to the additional conditions specified or incorporated below:

(1) Maximum Power Level The licensee is authorized to operate the facility at steady state reactor core power levels not in excess of 1850 megawatts (thermal).

(2) Technical Specifications The Technical Specifications contained in Appendix A, which is attached hereto, as revised through Amendment No. 237, is hereby incorporated into this license. Exelon Generation shall operate the facility in accordance with the Technical Specifications.

(3) Deleted Renewed License No. DPR-63 Amendment No. 191 thro1:1gh 210, 211, 213, 214, 215, 21e, 217, 218, 220, 222, 223, 224, 225, 227, 229, 231, 233, 234, 239,237 Corr-ectioR Letter Dated A1:1g1:1st 7, 2012 Corr:ectioR Letter Dated March 17, 2015 CorrectioR Letter dated J1:1ly 29, 2016

LIMITING CONDITION FOR OPERATION SURVEILLANCE REQUIREMENT 3.3.1 OXYGEN CONCENTRATION 4.3.1 OXYGEN CONCENTRATION Applicability: Applicability:

Applies to the limit on oxygen concentration within Applies to the periodic testing requirement for the the primary containment system in the power primary containment system oxygen concentration.

operating condition.

Objective: Objective:

To assure that in the event of a loss-of-coolant To assure that the oxygen concentration within the accident any hydrogen generation will not result in a primary containment system is within required limits.

combustible mixture within the primary containment system.

Specification: Specification:

a. The primary containment atmosphere shall be In accordance with the Surveillance Frequency reduced to less than four percent by volume Control Program, oxygen concentration shall be oxygen concentration with nitrogen gas while in determined.

the power operating condition, except as specified in "b" below.

AMENDMENT NO. 142,185.222, 237 124

LIMITING CONDITION FOR OPERATION SURVEILLANCE REQUIREMENT

b. If the containment oxygen concentration is greater than or equal to the four percent by volume limit while in the power operating condition and for transitory conditions during startup, shutdown and maintenance activities, restore the oxygen concentration to within the limit within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

c. If Specifications "a" or "b" above are not met, exit the power operating condition within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

AMENDMENT NO. 142. 185, 237 125

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, O.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 237 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-63 NINE MILE POINT NUCLEAR STATION, LLC EXELON GENERATION COMPANY, LLC NINE MILE POINT NUCLEAR STATION, UNIT 1 DOCKET NO. 50-220

1.0 INTRODUCTION

By letter dated June 26, 2018 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18177A044), as supplemented by letters dated February 25, 2019 (ADAMS Accession No. ML19056A387). and May 17, 2019 (ADAMS Accession No. ML19137A070), Exelon Generation Company, LLC (the licensee) submitted a license amendment request (LAR) to Renewed Facility Operating License No. DPR-63 for Nine Mile Point Nuclear Station, Unit 1 (Nine Mile Point 1). The LAR proposed to change the Nine Mile Point 1 Technical Specification (TS) Section 3.3.1, "Oxygen Concentration," to require inerting the primary containment to less than 4 percent by volume oxygen concentration within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of entering power operating condition. Also, the amendment adds a new requirement to identify required actions, if the primary containment oxygen concentration increases to greater than or equal to four volume percent while in the power operating condition.

On December 18, 2018, the U.S. Nuclear Regulatory Commission (NRC or the Commission) staff published a proposed no significant hazards consideration (NSHC) determination in the Federal Register (83 FR 64894) for the proposed amendment. Subsequently, by letters dated February 28, 2019, and May 17, 2019, the licensee provided additional information that expanded the scope of the amendment request as originally noticed in the Federal Register.

Accordingly, the NRC published a second proposed NSHC determination in the Federal Register on June 18, 2019 (84 FR 28346), which superseded the original notice in its entirety.

2.0 REGULATORY EVALUATION

2.1 System Description Title 10 of the Code of Federal Regulations (10 CFR) Section 50.44(b)(2), "Combustible gas control," sub-item (i) requires that all Boiling Water Reactors (BWRs) with Mark I and Mark II type containments have an inerted atmosphere. Nine Mile Point 1 has a Mark I containment.

The containment inerting system consists of equipment, such as nitrogen storage tanks, Enclosure 2

vaporizing units, necessary piping, valves, and instrumentation. The LAR only addresses oxygen concentration in the primary containment. Therefore, inerting system equipment is not within the scope of the NRC staff's review. Containment isolation valves used when inerting are safety related and addressed in other TS requirements.

2.2 Proposed TS Changes The current Nine Mile Point 1 TS Section 3.3.1, "Oxygen Concentration," requires the primary containment atmosphere to be reduced to less than 4 percent by volume oxygen concentration whenever the reactor coolant pressure is greater than 110 pounds per square inch gauge (psig) and the reactor is in power operating condition. Section 3.3.1 includes a 24-hour allowance during startup and shutdown. In addition, Section 3.3.1.c provides 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to bring oxygen concentration to below 4 percent by volume if oxygen concentration were found to be greater than 4 percent by volume at any time during power operation (e.g. surveillances), except for the 24-hour allowance during startup and scheduled shutdown. Nine Mile Point 1 TS Section 3.3.1.d states that failure to bring oxygen concentration to less than 4 percent oxygen concentration requires the reactor coolant pressure to be reduced to 110 psig or less within 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> (effectively a shutdown requirement).

The final proposed changes are described in the licensee's letter dated May 17, 2019, and are as follows (deletions shown with a strike through and additions shown in bold and underlined):

LIMITING CONDITION FOR OPERATION SURVEILLANCE REQUIREMENT 3.3.1 OXYGEN CONCENTRATION 4.3.1 OXYGEN CONCENTRATION Applicability: Applicability:

Applies to the limit on oxygen Applies to the periodic testing concentration within the primary requirement for the primary containment containment system in the power system oxygen concentration.

operating condition.

Objective:

Objective:

To assure that in the event of a loss-of-coolant accident any hydrogen To assure that the oxygen concentration generation will not result in a within the primary containment system combustible mixture within the primary is within the required limits.

containment system.

Specification: Specification:

a. The primary containment In accordance with the Surveillance atmosphere shall be reduced to less Frequency Control program, oxygen than four percent by volume oxygen concentration shall be determined.

concentration with nitrogen gas while in the power operating condition whenever tho reactor coolant pressure is greater than 110

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LIMITING CONDITION FOR OPERATION SURVEILLANCE REQUIREMENT operating oondition, except as specified in "b" and "c" below.

b. 'JVithin the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period subsequent to the roaster being plaoed in the run mode f.or the power operating oondition, the oontainment mcygen oonoentration shall be reduoed to less than f.our peroent by volume and maintained in this oondition. Deinerting may oommenoe 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> prior to a major refueling outage or other soheduled shutdown.

b.&. If the containment oxygen concentration is greater than or equal to the four percent by volume while in power operating condition and for transitory conditions during startup, shutdown and maintenance activities limit, exoept as allowed during startup and shutdown in "b" above, restore the oxygen concentration to within the limit within 2472 hours0.0286 days <br />0.687 hours <br />0.00409 weeks <br />9.40596e-4 months <br />.

c.Eh If specifications "a," or "b," ~

above are not met, the roaster ooolant pressure shall be reduoed to 110 psig or less within 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> exit the power operating condition within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

2.3 Reasons for the Proposed Change The current Nine Mile Point 1 TS Section 3.3.1 provides for a 24-hour period following startup (i.e., mode switch in run position) or before a scheduled shutdown in which the primary containment atmosphere does not have to be inerted. In its application dated June 26, 2018, the licensee stated that the current reference condition for this 24-hour time period is when the reactor mode switch is a combination of reactor system pressure being greater than 110 psig and in the power operating condition (mode switch in startup and run), and for shutdown the reference condition for the 24-hour time period is 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> prior to reaching the shutdown condition. To maximize time for surveillances and leak inspections, the licensee has been delaying transfer to the "run" mode as long as possible to delay the start of the 24-hour window.

The licensee further stated that the current 24-hour period does not provide sufficient time to perform in-containment equipment maintenance (e.g., inspections, tests, adjustments and minor repairs) without a complete shutdown of the reactor.

2.4 Applicable Regulatory Requirements and Guidance The NRC staff applied the following requirements to the evaluation of the LAR.

Pursuant to 10 CFR Section 50.44(b )(2)(i), "Combustible gas control for nuclear power reactors," all boiling water reactors with Mark I or Mark II type containments must have an inerted atmosphere. Section 50.44(a)(1) defines inerted atmosphere to mean a containment atmosphere with less than 4 percent oxygen by volume.

Section 50.36 to 10 CFR, "Technical specifications," requires, in part, that the operating license of a nuclear production facility include TSs. Paragraph 50.36(c)(2) of 10 CFR requires that the TSs include limiting conditions for operation (LCO), which are the lowest functional capability or performance levels of equipment required for safe operation of the facility. When an LCO of a nuclear power plant is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the TSs until the condition can be met.

3.0 TECHNICAL EVALUATION

3.1 Evaluation of lnerted Atmosphere As stated in the Federal Register on September 16, 2003 (68 FR 54123), given the relatively small volume and large zirconium inventory, the Mark I containments, without inerting, would have a high likelihood of failure from hydrogen combustion due to the potentially large concentration of hydrogen that a severe accident could cause in a very short duration. Mark I containments are inerted to minimize the primary containment conditional failure probability.

The design basis accident hydrogen production potential, where effective core cooling would be maintained, was determined to not be risk significant.

The TSs for reactors with Mark I containments have contained requirements for inerting during power operation before and after the rule change in calendar year 2003 came into effect, with an accompanying allowance during startup, shutdown, and surveillance failure. This allowance is necessary for certain inspections that the licensee needs to perform during startup and shutdown.

The NRC staff reviewed the proposed changes. The proposed changes delete the requirement to inert the containment at reactor coolant pressure greater than 110 psig with a 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> allowance and replaces it with a requirement to inert while in power operating condition with a 72-hour allowance. The licensee stated that the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> allowance is based on operating experience for startup, maintenance, and shutdown conditions. The licensee further stated that 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is a reasonable amount of time, and it is based on 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to de-inert containment prior to shutdowns and/or in preparation for maintenance; 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to perform work inside containment and 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to re-inert. During startup, the transition period prior to entering the mode of applicability includes associated inspection, post maintenance test activities, and potential maintenance work inside the drywell while raising the primary system temperature and pressure. For shutdown, activities include preparations for initial inspections to validate outage work scope, and the time required to transition from "run" mode to shutdown condition without requiring a reactor trip from power and the associated transients on the reactor and various system components. Based on the information provided by the licensee, the NRC staff concludes that the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is a reasonable time that is adequate for personnel to conduct the necessary activities in containment without wearing a self-contained breathing apparatus.

lnerting the primary containment while in power operating condition is consistent with the intent of 10 CFR 50.44 to maintain an overall high probability of primary containment function, considering the very low probability of a severe accident during these short time periods. The staff determined that the presence of a low oxygen concentration was not safety significant for a spectrum of design basis accidents that have higher overall frequencies of occurrence than potential severe accidents. Therefore, the staff determined that the 72-hour allowance is appropriate considering the safety significance and the operational benefits provided by completion of necessary inspection or maintenance inside primary containment without the need for operators to wear a self-contained breathing apparatus.

3.2 Evaluation of Proposed TS changes Applicability The licensee proposes to add the verbiage "in the power operating condition" at the end of the current applicability statement in TS 3.3.1. Nine Mile Point 1, TS 1.1, "Reactor Operating Conditions," sub-item "d" defines "power operating condition" as (1) Reactor mode switch is in startup or run position and (2) Reactor critical or criticality is possible due to control rod withdrawal. The proposed change provides additional clarity regarding the applicability of TS 3.3.1 to all power operating conditions and the NRC staff finds it acceptable.

TS 3.3.1.a The licensee proposes to replace the words "whenever the reactor coolant pressure is greater than 110 psig and the reactor is in the power operating condition" with "while in the power operating condition." In the context of the "applicability" and the definition provided in for "power operating condition" in TS 1.1.d, this is the condition that could present the highest probability of an event that could lead to large amounts of hydrogen and primary containment conditional failure probability. The change is appropriate and acceptable.

TS 3.3.1.b Deleted in its entirety.

TS 3.3.1.c Renamed as TS 3.3.1.b. Replaces the words "except as allowed during startup and shut down -

in "b" above" with "while in the power operating condition and for transitory conditions during startup, shutdown and maintenance activities." In addition, "24" hours are replaced with "72" hours. The licensee justification for the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is reasonable and acceptable. The NRC staff notes that the deletion of existing TSs 3.3.1.b and modified TS 3.3.1.c (renamed as TS 3.3.1.b) removes any references to de-inerting prior to a major refueling outage or other scheduled shutdowns. The revised wording in new TS 3.3.1.b clarifies that the 72-hour allowance is limited to transitory conditions during startup, shutdown and maintenance activities.

TS 3.3.1.d Renamed as TS 3.3.1.c. Replaces the words "the reactor coolant pressure shall be reduced to 11 O psig or less within ten hours" with "exit the power operating condition within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />." This change provides a clearer action when the LCO is not met or the other actions cannot be completed. The reduction of the reactor coolant pressure to 11 O psig or less is not clear

because the plant could still be in the reactor operation condition instead of a condition that the LCO is no longer applicable. The proposed 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> is consistent with other TS actions to change conditions (or modes for standard technical specifications (STS) plants) to shutdown condition-hot from power operating condition. The revised wording in the renamed TS 3.3.1.c clarifies that the applicable condition (i.e., power operating condition) must be exited (i.e.,

changed to shutdown condition), if the required actions in TS 3.3.1.a or renamed TS 3.3.1.b cannot be completed. The change is appropriate and acceptable.

3.3 Technical Conclusion The NRC staff determined that the proposed change meets 10 CFR 50.44(b )(2)(i) because it retains the requirement that the containment have an inerted atmosphere at power. The NRC staff determined that the 72-hour allowance is reasonable, because it allows limited time to perform inerting or de-inerting and necessary inspection or maintenance. The NRC staff determined that the proposed change meets the requirements of 10 CFR 50.36(c)(2) because the proposed revision to Section 3.3.1 of the Nine Mile Point 1 TS includes more appropriate remedial actions.

4.0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION

The Commission may issue a license amendment before the expiration of the 60-day period, provided that its final determination is that the amendment involves no significant hazards consideration. This amendment is being issued prior to the expiration of the 60-day period.

Therefore, a final finding of no significant hazards consideration follows.

The Commission has made a final determination that the amendment request involves no significant hazards consideration. Under the Commission's regulations in 10 CFR 50.92, this means that operation of the facility in accordance with the proposed amendment does not (1) involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) involve a significant reduction in a margin of safety.

As required by 10 CFR 50.91 (a), by letter dated June 26, 2018, the licensee provided its analysis of the issue of no significant hazards consideration, which is presented below:

1. Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No.

The proposed change modifies the Technical Specifications (TS) by adopting containment inerting and de-inerting requirements that are consistent with the guidance of NUREG-1433, "Standard Technical Specifications - General Electric BWR/4 Plants, Volume 1, Revision 4.0,"

published April 2012. The proposed change will allow inerting of the primary containment within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of exceeding 15 percent (%) Rated Thermal Power (RTP), and de-inerting 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> prior to reducing reactor power to less than or equal to 15% RTP. Also, a new TS condition will be added to identify required actions if the primary containment oxygen concentration increases to greater than or equal to 4% by volume while in the power operating condition. The proposed change does not alter the

physical configuration of the plant, nor does it affect any previously analyzed accident initiators. The accident analysis assumes that a Loss of Coolant Accident (LOCA) occurs at 100% RTP. The consequences of a LOCA at less than or equal to 15% RTP would be much less severe, and produce less hydrogen than a LOCA at 100% RTP.

Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No.

The proposed change adopts the STS guidance regarding containment inerting/de-inerting requirements. The proposed change introduces no new mode of plant operation and does not involve any physical modification to the plant. The proposed change is consistent with the current safety analysis assumptions. No setpoints are being changed which would alter the dynamic response of plant equipment. Accordingly, no new failure modes are introduced.

Therefore, the proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.

3. Does the proposed amendment involve a significant reduction in a margin of safety?

Response: No.

The proposed change revises the Applicability presentation of the Oxygen Concentration TS. No safety limits are affected. The Oxygen Concentration TS requirements assure sufficient safety margins are maintained, and that the design, operation, surveillance methods, and acceptance criteria specified in applicable codes and standards (or alternatives approved for use by the NRC) will continue to be met as described in the plants' licensing basis. The proposed change does not adversely affect existing plant safety margins or the reliability of the equipment assumed to operate in the safety analysis. As such, there are no changes being made to safety analysis assumptions, safety limits, or limiting safety system settings that would adversely affect plant safety.

Therefore, the proposed change does not result in a significant reduction in a margin of safety.

Based on the above evaluation, the NRC staff concludes that the three standards of 10 CFR 50.92(c) are satisfied. Therefore, the NRC staff has made a final determination that no significant hazards consideration is involved for the proposed amendment and that the amendment should be issued as allowed by the criteria contained in 10 CFR 50.91.

5.0 STATE CONSULTATION

In accordance with the Commission's regulations, the New York State official was notified of the proposed issuance of the amendment on June 21, 2019. The State official had no comments.

6.0 ENVIRONMENTAL CONSIDERATION

The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20, and changes surveillance requirements. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration in the Federal Register on June 18, 2019 (84 FR 28346) and there has been no public comment on such finding.

Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

7.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) there is reasonable assurance that such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor: N. Karipineni Date: July 30, 2019

B. Hanson

SUBJECT:

NINE MILE POINT NUCLEAR STATION, UNIT 1 - ISSUANCE OF AMENDMENT NO. 237 RE: CHANGES TO CONTAINMENT OXYGEN CONCENTRATION REQUIREMENTS (EPID L-2018-LLA-0183) DATED JULY 30, 2019 DISTRIBUTION:

PUBLIC PM File Copy RidsNrrDorlLpl 1 RidsRgn1 MailCenter RidsACRS_MailCTR RidsNrrLACSmith RidsNrrPMNineMilePoint RidsNrrPMExelon RidsNrrDssScpb RidsNrrDssSrxb RidsNrrDssStsb NKaripineni, NRR CTilton, NRR ASallman, NRR ADAMS Access1on No.: ML19176A086 *b>V memo **b"'ema1*1 OFFICE DORL/LPL 1/PM DORL/LPL 1/LA DSS/SCPB/BC* DSS/STSB/BC** DSS/SRXB/BC**

NAME MMarshall CSmith SAnderson PSnyder JBorromeo DATE 07/05/2019 07/02/2019 06/19/2019 07/02/2019 06/28/2019 OFFICE OGG (NLO)** DORL/LPL 1/BC DORL/LPL 1/PM NAME KGamin JDanna MMarshall DATE 07/22/2019 07/26/2019 07/30/2019 OFFICIAL RECORD COPY