ML24040A052

Independent Spent Fuel Storage Installation - Report of Changes, Tests. and Experiments -10 CFR 50.59 and 10 CFR 72.48

ML24040A052
Person / Time
Site:	Calvert Cliffs, 07200078
Issue date:	02/09/2024
From:	Pat Navin Constellation Energy Generation
To:	Office of Nuclear Material Safety and Safeguards, Office of Nuclear Reactor Regulation, Document Control Desk
References
Download: ML24040A052 (1)

Text

Constellation February 09, 2024 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 Renewed Facility Operating License Nos. DPR-53 and DPR-69 NRC Docket Nos. 50-317 and 50-318 Calvert Cliffs Nuclear Power Plant Patrick D. Navin Site Vice President Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657 410-495*5200 Office 717-817*6827 Mobile www exetoncoro com Pat Navin(g_constellat1on_com 10 CFR 50.59 10 CFR 72.48 Independent Spent Fuel Storage Installation, License No. SNM-2505 NRC Docket Nos. 72-8 and 72-78

Subject:

Report of Changes, Tests. and Experiments -10 CFR 50.59 and 10 CFR 72.48 In accordance with 10 CFR 50.59(d)(2) and 10 CFR 72.48(d)(2), a report of changes, tests and experiments is provided as Attachment (1). The attachment contains brief descriptions of changes, tests, and experiments approved under the provisions of 10 CFR 50.59 and 10 CFR 72.48 between January 1, 2022, and December 31, 2023. There were no 72.48 Evaluations performed during this time period.

There are no regulatory commitments contained in this correspondence.

Should you have questions r arding this matter, please contact Mr. Larry D. Smith at (410) 495 5219.

Respectfully'.;J

/

1 /{_j' ~

Patrick D. Navin Site Vice President

Office of Nuclear Regulatory Research February 09, 2024 Page 2 PFN/LDS/aj

Attachment:

(1)

Calvert Cliffs Nuclear Power Plant Report of Changes, Tests, and Experiments

[10 CFR 50.59(d)(2) and 10 CFR 72.48(d)(2))

cc:

NRC Project Manager, Calvert Cliffs NRC Regional Administrator, Region 1 NRC Sr. Resident Inspector, Calvert Cliffs S. Seaman, MD-DNR S. Helton, NMSS

ATTACHMENT (1)

CALVERT CLIFFS NUCLEAR POWER PLANT REPORT OF CHANGES, TESTS, AND EXPERIMENTS

[10 CFR S0.59(d)(2) and 10 CFR 72.48(d)(2)1 Calvert Cliffs Nuclear Power Plant February 09, 2024

Document Id SE00578 Subject Summary Doc Type 50.59 Rev Status Approved Revision 0000 U2 Control Element Drive Logic and Display System Replacement (ECP-19-000541)

Proposed Activity:

Date Issued 5/12/2022 Replace the obsolete Control Element Drive System (CEDS) with a Digital Control Element Drive Control System (DCEDCS).

The DCEDCS utilizes Triple Module Redundant (TMR) Programmable Logic Controllers (PLCs) as the backbone of the system so that no single failure within the system can prevent control element movement, cause a dropped control element or cause a plant trip.

Reason for Activity:

The Unit 2 Control Element Drive System (CEDS), which includes the Coil Power Programmer (CPP), the CEDS Control Panel, and Control Element Assembly Position Display System (CEAPDS), is near the end of its life cycle and parts are obsolete. An upgrade is required to continue operation of the unit for the next 30 years.

Effect of Activity:

The activity will result in the following changes to the ways in which the Operators interface with the Control Element Drive System (CEDS). They include:

A new semi-automatic control mode of operation which automatically moves a selected CEA or CEA group to a user-entered location without continuous input from the Operator.

A new enhanced Human Machine Interface (HMI) that employs "touch screen" technology, video displays, and user interfaces for improved information presentation and ergonomics.

There are no changes to the design bases or the safety analysis as a result of this activity.

==

Conclusions:==

The primary function of the CEA is to control the core axial power distribution and to provide instantaneous reactivity to shut down the reactor during controlled procedures and during abnormal and emergency conditions. A CEA Drop event is

Document Id SE00580 Subject Summary Doc Type 50.59 Rev Status Approved Revision 0000 Implementation of Calvert Cliffs Low Power Physics Testing reduction (ECP-22-000407)

Proposed Activity:

Date Issued 2/17/2023 This activity implements new methods for confirming low power physics testing as it relates to the Hot Zero Power (HZP)

Beginning of Life (BOL) Moderator Temperature Coefficient (MTC) check and the Rod Worth Measurement check. With the requirements for HZP BOL MTC confirmation and rod worth testing confirmation, implemented as outlined in a PWR Owner's Group Report, the physical plant manipulations/testing for HZP MTC and rod worth can be bypassed. This activity does not modify or change the process of minimum limit MTC confirmation, typically performed at End of Life (EOL). The PWR Owner's Group has a separate EOL MTC elimination method that is not being employed here.

Reason for Activity:

This activity is being made to reduce the frequency of HZP BOL MTC and rod worth testing during startup. A reduction in the time to perform HZP MTC and rod worth testing will result in reducing the time associated with the return to power operations after a refueling/ maintenance outage which in turn will reduce the time spent in unique plant configurations and performing operations maneuvers at lower power conditions. The utilization of the PWR Owners Group Report for rod worth testing elimination provides Calvert Cliffs with an alternate means to bypass rod worth testing. Furthermore, this will minimize unnecessary maneuvers that could cause undue wear and tear on the control rod drive mechanisms.

Effect of Activity:

The effect of this activity would be to minimize the frequency of HZP MTC and rod worth testing during startup. This activity will impact TS Bases, UFSAR updates and require updates to procedures at Calvert Cliffs and NF PWR Core Design procedure updates.

==

Conclusions:==

Document Id SE00581 Subject Summary Doc Type 50.59 Rev Status Approved Revision 0000 Ul Control Element Drive Logic and Display System Replacement (ECP-19-000538)

Proposed Activity:

Date Issued 07/11/2023 Replace the obsolete Control Element Drive System (CEDS) with a Digital Control Element Drive Control System (DCEDCS). The DCEDCS utilizes Triple Module Redundant (TMR) Programmable Logic Controllers (PLCs) as the backbone of the system so that no single failure within the system can prevent control element movement, cause a dropped control element or cause a plant trip.

Reason for Activity The Unit 1 Control Element Drive System (CEDS), which includes the Coil Power Programmer (CPP), the CEDS Control Panel, and Control Element Assembly Position Display System (CEAPDS), is near the end of its life cycle and parts are obsolete. An upgrade is required to continue operation of the unit for the next 30 years.

Effect of Activity:

The activity will result in the following changes to the ways in which the Operators interface with the Control Element Drive System (CEDS). They include:

A new semi-automatic control mode of operation which automatically moves a selected CEA or CEA group to a user-entered location without continuous input from the operator.

A new enhanced Human Machine Interface (HMI) that employs "touch screen" technology, video displays, and user interfaces for improved information presentation and ergonomics.

There are no changes to the design bases or the safety analysis as a result of this activity.

==

Conclusions:==

The primary function of the CEA is to control the core axial power distribution and to provide instantaneous reactivity to shut down the reactor during controlled procedures and during abnormal and emergency conditions. A CEA Drop event is

Document ID SE00582 Subject Summary Doc Type 50.59 Rev Status Approved Revision 0000 Date Issued 10/16/2023 Implement the Biasi Critical Heat Flux correlation for the Post-Trip Steam Line Break Event (ECP-23-000248)

Proposed Activity:

This activity implements the Biasi Critical Heat Flux (CHF) correlation for the Calvert Cliffs Units 1 and 2 Post-Trip Steam Line Break Event (UFSAR Chapter 14.14).

Reason for Activity Calvert Cliffs previously changed the modified Barnett CHF correlation Departure from Nucleate Boiling Ratio (DNBR) limit used in the Post-Trip Steam Line Break (SLB) event via a 10CFR50.59 Evaluation that concluded NRC prior review and approval was not required. The NRC took exception to that conclusion and issued a Non-Cited Violation (NCV). This activity implements the long-term corrective action (Biasi correlation) established to address the NCV.

Effect of Activity:

Changing the CHF correlation from modified Barnett to Biasi used in the Post-Trip SLB event has no impact on plant operation and no procedure changes are required. No different Operator actions are required.

The change to the Biasi CHF correlation changes the analytical margin between the predicted minimum DNBR during the transient and the limit at which fuel failure is assumed to occur. In all cases, positive margin remains to a fuel failure. The amount of fuel failure predicted in the UFSAR for the Post-Trip SLB remains unchanged.

Implementation of the Biasi correlation requires updating the UFSAR Chapter 14 critical heat flux correlation discussions and issuing revisions to the U1C26 and U2C25 Core Operating Limits Reports (COLRs) to add to the List of Approved Methodologies section the recently NRC approved methodology supplement for the Biasi correlation.

==

Conclusions:==

The NRC recently generically approved Supplement 2 to EMF-2310 which provides limits for using the Biasi CHF correlation for Post-Trip steam line break event. Calvert will implement that Supplement methodology.

All NRC SER and Topical Report requirements are satisfied.

Document Id SE00583 Doc Type 50.59 Rev Status Approved Revision 0000 Date Issued 09/28/2023 determined the new digital radiation monitors will exhibit a sufficiently low likelihood of failure and thus will not result in more than a minimal increase of the frequency of an accident, or likelihood of occurrence of a malfunction of an SSC, nor does it create a possibility for an accident of a different type, nor does it create the possibility for a malfunction of an SSC important to safety with a different result from any previously evaluated. The evaluation determined that a license Amendment Request (LAR) is not required prior to implementation of this design equivalent change.