ML19238A308

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Issuance of Amendment - Regarding Adoption of TSTF-476, Improved Banked Position Withdrawal Sequence Control Rod Insertion Process
ML19238A308
Person / Time
Site: Clinton Constellation icon.png
Issue date: 09/30/2019
From: Joel Wiebe
Plant Licensing Branch III
To: Bryan Hanson
Exelon Generation Co
Wiebe J
References
EPID L-2018-LLA-0260
Download: ML19238A308 (12)
v • d • e


Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 September 30, 2019 Mr. Bryan C. Hanson Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer (CNO)

Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

CLINTON POWER STATION, UNIT NO. 1 - ISSUANCE OF AMENDMENT REGARDING ADOPTION OF TSTF-476, "IMPROVED BANKED POSITION WITHDRAWAL SEQUENCE CONTROL ROD INSERTION PROCESS" (EPID L-2018-LLA-0260)

Dear Mr. Hanson:

The U.S. Nuclear Regulatory Commission (the Commission) has issued the enclosed Amendment No. 226 to Facility Operating License No. NPF-62 for the Clinton Power Station, Unit No. 1. The amendment is in response to your application dated September 28, 2018 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18271A217).

The amendment makes technical specification changes that are consistent with NRC approved Industry Technical Specification Task Force (TSTF) Traveler, TSTF-476, Revision 1, dated January 9, 2007 (ADAMS Accession No. ML070090561)

A copy of the Safety Evaluation is also enclosed. The Notice of Issuance will be included in the Commission's next biweekly Federal Register notice.

Sincerely, Joel S. Wiebe, Senior Project Manager Plant Licensing Branch Ill Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-461

Enclosures:

1. Amendment No. 226 to NPF-62
2. Safety Evaluation cc: Listserv

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 EXELON GENERATION COMPANY, LLC DOCKET NO. 50-461 CLINTON POWER STATION, UNIT NO. 1 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 226 License No. NPF-62

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

A. The application for amendment by Exelon Generation Company, LLC (the licensee), dated September 28, 2018, 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.

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 Facility Operating License No. NPF-62 is hereby amended to read as follows:

Enclosure 1

(2)

  • Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A and the Environmental Protection Plan contained in Appendix B, as revised through Amendment No. 226, are hereby incorporated into this license.

Exelon Generation Company shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

3. This license amendment is effective as of its date of issuance and shall be implemented within 90 days of the date of issuance.

Lisa M. Regner, Acting Branch Chief Plant Licensing Branch Ill Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the Technical Specifications and Facility Operating License Date of Issuance: September 3 O, 2 O1 9

ATTACHMENT TO LICENSE AMENDMENT NO. 226 CLINTON POWER STATION, UNIT NO. 1 FACILITY OPERATING LICENSE NO. NPF-62 DOCKET NO. 50-461 Replace the following pages of the Facility Operating License and 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 License NPF-62 License NPF-62 Page 3 Page 3 TSs TSs 3.3-18 3.3-18

(4) Exelon Generation Company, pursuant to the Act and to 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; (5) Exelon Generation Company, 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 calibration or associated with radioactive apparatus or components; (6) Exelon Generation Company, pursuant to the Act and 10 CFR Parts 30, 40, and 70, to possess, but not separate, such byproduct and special nuclear materials as may be produced by the operation of the facility.

Mechanical disassembly of the GE14i isotope test assemblies containing Cobalt-60 is not considered separation; and (7) Exelon Generation Company, pursuant to the Act and 10 CFR Parts 30, to intentionally produce, possess, receive, transfer, and use Cobalt-60.

C. This license shall be deemed to contain and is subject to the conditions specified in the Commission's regulations set forth in 10 CFR Chapter I and 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 subject to the additional conditions specified or incorporated below:

( 1) Maximum Power Level Exelon Generation Company is authorized to operate the facility at reactor core power levels not in excess of 3473 megawatts thermal (100 percent rated power) in accordance with the conditions specified herein.

(2) Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A and the Environmental Protection Plan contained in Appendix B, as revised through Amendment No. 226, are hereby incorporated into this license.

Exelon Generation Company shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

Amendment No. 226

Control Rod Block Instrumentation 3.3.2.1 Table 3.3.2.1-1 (page 1 of 1)

Control Rod Block Instrumentation APPLICABLE MODES OR OTHER SPECIFIED REQUIRED SURVEILLANCE FUNCTION CONDITIONS CHANNELS REQUIREMENTS

1. Rod Pattern Control System la)
a. Rod withdrawal limiter 2 SR 3.3.2.1.1 SR 3.3.2.1.6 SR 3 .3 .2 .1.9 lb) 2 SR 3.3.2.1.2 SR 3.3.2.1.5 SR 3.3.2.1.7 SR 3 .3 .2 .1.9
b. Rod pattern controller 1 {cl, 2 (c) 2 SR 3.3.2.1.3 SR 3.3.2.1.4 SR 3.3.2.1.5 SR 3.3.2.1.7 SR 3.3.2.1.9 ld)
2. Reactor Mode Switch-Shutdown Position 2 SR 3 .3 .2 .1.8 (a) THERMAL POWER greater than the RWL HPSP.

(b) THERMAL POWER> 29.2% RTP and less than or equal to the RWL HPSP.

(c) With THERMAL POWER~ 16.7% RTP, except during the reactor shutdown process if the coupling of each withdrawn control rod has been confirmed.

(d) Reactor mode switch in the shutdown position.

CLINTON 3.3-18 Amendment No. 226

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 226 TO FACILITY OPERATING LICENSE NO. NPF-62 EXELON GENERATION COMPANY, LLC CLINTON POWER STATION, UNIT NO. 1 DOCKET NO. 50-461

1.0 INTRODUCTION

By letter dated September 28, 2018 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18271A217), Exelon Generation Company, LLC (EGC, the licensee) for Clinton Power Station (CPS), Unit 1, requested to amend CPS technical specifications (TSs) to add a footnote to TS Table 3.3.2.1-1, "Control Rod Block Instrumentation." The application states that the changes are the adoption of Technical Specification Task Force (TSTF)-476, Revision 1, "Improved [Banked Position Withdrawal Sequence] BPWS Control Rod Insertion Process (NED0-33091-A)." The new control rod insertion process is described in Topical Report NED0-33091-A, Revision 2, "Improved BPWS Control Rod Insertion Process," dated July 2004 (ADAMS Accession No. ML042230366), which includes the NRC safety evaluation (SE) dated June 16, 2004 (ADAMS Accession No. ML041700479).

The TSTF-476 allows use of the improved BPWS during shutdowns if the coupling of each withdrawn control rod is confirmed. TSTF-476, Revision 1 (ADAMS Accession No. ML070090561 ), was announced for availability in the Federal Register on May 23, 2007. The U.S. Nuclear Regulatory Commission (NRC or Commission) staff's June 16, 2004, SE states that its review considered control rod drive (CRD) hydraulic systems from plants of various boiling-water reactor (BWR) designs, and found that the CRD systems of BWR/2 through BWR/6 designs are very similar with respect to the mechanisms for rod insertion, withdrawal, and locking. CPS, Unit 1, is a BWR/6 plant and TS Table 3.3.2.1-1 is similar to the TS Table

2.0 REGULATORY EVALUATION

Under Title 10 of the Code of Federal Regulations (10 CFR) 50.92(a), determinations on whether to grant an applied-for license amendment are to be guided by the considerations that Enclosure 2

govern the issuance of initial licenses or construction permits to the extent applicable and appropriate. Both the common standards for licenses and construction permits in 10 CFR 50.40(a), and those specifically for issuance of operating licenses in 10 CFR 50.57(a)(3),

provide that there must be "reasonable assurance" that the activities at issue will not endanger the health and safety of the public.

Section 50.36(c)(2)(i) of 10 CFR states that the TS will include, among other things, limiting conditions for operation (LCOs ), which are the lowest functional capability or performance levels of equipment required for safe operation of the facility.

The control rod drop accident (CRDA) is the design-basis accident for the subject TS change.

To minimize the impact of a CRDA, the BPWS process was developed to minimize control rod reactivity worth for BWR plants. The proposed improved BPWS further simplifies the control rod insertion process. The NRC staff followed the guidelines of NUREG-0800, Standard Review Plan for the "Review of Safety Analyses Reports for Nuclear Power Plants," Section 15.4.9, dated July 1981 (ADAMS Accession No. ML052350427), and referred to General Design Criteria (GDC) 28 as the regulatory requirement when evaluating the proposed improved BPWS. GDC 28 states that the reactivity control systems shall be designed with appropriate limits on the potential amount and rate of reactivity increase to assure that the effects of postulated reactivity accidents can neither: ( 1) result in damage to the reactor coolant pressure boundary greater than limited local yielding nor (2) sufficiently disturb the core, its support structures or other reactor pressure vessel internals to impair significantly the capability to cool the core.

3.0 TECHNICAL EVALUATION

3.1 Licensee's Proposed Changes:

CPS LCO 3.3.2.1 addresses "Control Rod Block Instrumentation" and states "The control rod block instrumentation for each Function in Table 3.3.2.1-1 ["Control Rod Block Instrumentation"]

shall be OPERABLE."

Current Table 3.3.2.1-1, FUNCTION 1.b, addresses the rod pattern controller, and states:

APPLICABLE MODES OR OTHER SPECIFIED REQUIRED SURVEILLANCE FUNCTION CONDITIONS CHANNELS REQUIREMENTS

b. Rod pattern controller 1(cl, 2 2 SR 3.3.2.1.3 SR 3.3.2.1.4 SR 3.3.2.1.5 SR 3.3.2.1.7 SR 3.3.2.1.9 Current Note (c):

(c) With THERMAL POWER s 16.7% RTP.

The applicant proposes to revise footnote (c) to Table 3.3.2.1-1, FUNCTION 1.b, and make the footnote applicable to Mode 2 instead of just Mode 1 as shown below:

APPLICABLE MODES OR OTHER SPECIFIED REQUIRED SURVEILLANCE FUNCTION CONDITIONS CHANNELS REQUIREMENTS

b. Rod pattern controller 1<c) 2<c) 1 2 SR 3.3.2.1.3 SR 3.3.2.1.4 SR 3.3.2.1.5 SR 3.3.2.1. 7 SR 3.3.2.1.9 Revised Note (c ):

(c) With THERMAL POWER s 16.7% RTP, except during the reactor shutdown process if the coupling of each withdrawn control rod has been confirmed.

3.2 NRC Staff Evaluation TSTF-476, Revision 1, states that the improved BPWS provides the following benefits:

  • allows the plant to reach the all-rods-in condition prior to significant reactor cool down, which reduces the potential for re-criticality as the reactor cools down;
  • reduces the potential for an operator reactivity control error by reducing the total number of control rod manipulations;
  • minimizes the need for manual scrams during plant shutdowns, resulting in less wear on CRD system components and CRD mechanisms; and,
  • eliminates unnecessary control rod manipulations at low power, resulting in less wear on reactor manual control and CRD system components.

The NRC staff reviewed the licensee's updated safety analysis report, Revision 20, Chapter 3.0, "Design of Structures, Components, Equipment and Systems," dated October 24, 2018 (ADAMS Accession No. ML18304A397), which provides the licensee's evaluation of the design bases of the plant as measured against the NRC GDC for nuclear power plants (Appendix A of 10 CFR 50), effective May 21, 1971, and subsequently amended February 20, 1976. CPS's evaluation against GDC 28 states, "The design features of the reactivity control system which limit the potential amount and rate of reactivity increase ensure that Criterion 28 is satisfied for all postulated reactivity accidents."

As stated in the NRC staff's safety evaluation (SE) for NED0-33071 dated June 16, 2004, the original BPWS was developed to minimize the control rod worth and mitigate the consequences of a CRDA from occurring during startup. This procedure also directly applies to the control rod insertion sequence during shutdown after power is lower than the low power set point (LPSP).

The NRC staff found in its June 16, 2004, SE that during a reactor shutdown process for all operating BWRs when each control rod is given an insert signal, there exists no single failure of the CRD hydraulic or mechanical system that could result in a control rod withdrawal out of the core of more than 6 inches (equivalent to one CRD index tube drive notch length). EGC stated

in its letter dated September 28, 2018, that it verified, in accordance with NED0-33091-A, Revision 2, that no single failure of the BWR CRD mechanical or hydraulic system can cause a control rod to drop completely out of the reactor core during the shutdown process.

The NRC staff's June 16, 2004, SE determined that implementation of the improved BPWS requires that operators confirm that control rod coupling integrity for all rods fully withdrawn will ensure proper coupling during the control rod insertion process and any possible rod withdrawal after reactor power drops below the LPSP.

The CPS TS Table 3.3.2.1-1, FUNCTION 1.b. "Rod pattern controller," enforces the original BPWS. The rod pattern controller is currently required to be operable in MODE 2 and in MODE 1 when reactor thermal power is less than or equal to 16. 7% during startup or shutdown. The licensee's proposed changes (see Section 3.1, above) to the CPS TS would require the rod pattern controller to be operable in both MODE 2 and MODE 1 when rated thermal power is less than or equal to 16. 7 percent, except during the reactor shutdown process if the coupling of each withdrawn control rod has been confirmed. The NRC staff determined in its June 16, 2004, SE that the requirement to confirm the coupling of each withdrawn control rod before allowing the rod pattern controller to be taken out of service ensures that no one single failure can result in a CRDA.

Based on the rod pattern controller minimizing control rod worth and the confirmation of control rod coupling to reduce the likelihood of a CRDA during the shutdown process with the rod pattern controller out of service (which allows implementation of the improved BPWS), the NRC staff determined that there is reasonable assurance that implementation of the improved BPWS during shutdown will not endanger the health and safety of the public. Therefore, the NRC staff finds that the revised LCO continues to meet 10 CFR 50.36(c)(2)(i) by continuing to specify the lowest functional capability or performance levels of equipment required for safe operation of the facility.

In summary, the NRC staff finds that the proposed TS is acceptable because it ensures proper use of the original BPWS (rod pattern controller required to be operable) to reduce control rod worth and the improved BPWS (rod pattern controller not required to be operable) to reduce the likelihood of a CRDA from occurring while power is below the LPSP and that the proposed TS changes do reflect the plant's GDC 28 based design.

In its letter dated September 28, 2018, the licensee committed to the following procedural changes prior to the implementation of its proposed changes:

1. Before reducing power to the LPSP, operators shall confirm control rod coupling integrity for all rods that are withdrawn. Control rods that have not been confirmed coupled and which are in intermediate positions must be fully inserted prior to power reduction to the LPSP. No action is required for fully-inserted control rods.

If a shutdown is required and all rods which are not confirmed coupled cannot be fully inserted prior to the power dropping below the LPSP, then the original/standard BPWS must be adhered to. The original/standard BPWS can be found in Licensing Topical Report NED0-21231, "Banked Position Withdrawal Sequence," January 1977, and is referred to in NUREG-1433 and NUREG-1434.

2. After reactor power drops below the LPSP, rods may be inserted from notch position 48 to notch position 00 without stopping at the intermediate

positions. However, it is recommended that operators insert control rods in the same order as specified for the original/standard BPWS as much as reasonably possible. When in the process of shutting down following improved BPWS with the power below the LPSP, no control rod shall be withdrawn unless the control rod pattern is in compliance with standard BPWS requirements.

The NRC staff notes that the licensee commitments are consistent with NED0-33091-A, Revision 2. However, the NRC staff did not rely on these commitments for determining the acceptability of the licensee's proposed TS change because the TS change specifies requirements for the proper implementation of the improved BPWS.

4.0 STATE CONSULTATION

In accordance with the Commission's regulations, the NRC staff notified the Illinois State official on August 26, 2019, of the proposed issuance of the amendments. The State official had no comments.

5.0 ENVIRONMENTAL CONSIDERATION

The amendments change requirements with respect to the installation or use of facility components located within the restricted area as defined in 10 CFR Part 20 or change inspections or surveillance requirements. The NRC staff has determined that the amendments involve 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, which was published in the Federal Register on November 20, 2018 (83 FR 58611 ), that the amendments involve no significant hazards consideration, and there has been no public comment on such finding. Accordingly, the amendments meet 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 amendments.

6.0 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 amendments will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributors: J. Wiebe R. Grover Date of issuance: September 3 O, 2 o1 9

ML19238A308 *via e-mail **via memo OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DSS/STSB/BC OGC NAME JWiebe SRohrer PSnyder** DRoth*, NLO w/com DATE 9/25/19 9/25/19 8/5/19 9/24/19 OFFICE NRR/DORL/LPL3/BC NRR/DORL/LPL3/PM NAME LRegner JWiebe DATE 9/26/19 9/30/19

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