L-25-049, Submittal of Report of Facility Changes, Tests and Experiments

Submittal of Report of Facility Changes, Tests and Experiments

ML25055A222
Person / Time
Site:	Beaver Valley
Issue date:	02/24/2025
From:	Blair B Vistra Operations Company
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
L-25-049
Download: ML25055A222 (1)

Text

L-25-049 February 24, 2025 A TIN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

Subject:

Beaver Valley Power Station, Unit No. 2 Docket No. 50-412, License No. NPF-73 Report of Facility Changes, Tests and Experiments Beaver Valley Power Station Barry N. Blair Site Vice President P.O. Box4 200 State Route 3016 Shippingport, PA 15077 724-682-5234 10 CFR 50.59(d)(2)

In accordance with 10 CFR 50.59(d)(2), Vistra Operations Company LLC hereby submits the attached Report of Facility Changes, Tests and Experiments for Beaver Valley Power Station, Unit 2 (BVPS-2). This report reflects the implemented changes, tests and experiments that were evaluated pursuant to 10 CFR 50.59 during the period of February 1, 2023 through January 31, 2025.

There are no regulatory commitments contained in this submittal. If there are any questions, or if additional information is required, please contact Jack Hicks, Senior Manager, Licensing, at (254) 897-6725 or jack.hicks@vistracorp.com.

Attachment:

Beaver Valley Power Station, Unit 2, Report of Facility Changes, Tests and Experiments cc:

NRC Region I Administrator NRC Resident Inspector NRC Project Manager Director BRP /DEP Site BRP / DEP Representative EPA-OR VE 0

00

Attachment L-25-049 Beaver Valley Power Station, Unit 2 Report of Facility Changes, Tests and Experiments Page 1 of 6

Title:

Site Boundary and Control Room Doses following a Main Steam Line Break based on Core Uprate and Alternative Source Term Methodology Activity

Description:

The proposed activity is to revise the calculation that determines the maximum allowable accident induced steam generator tube leakage and the corresponding site boundary and control room doses following a main steam line break (MSLB) based on core uprate and alternative source term (AST) methodology. The revision includes changes to the steaming duration, the timing of the control room envelope (CRE) purge, and offsite breathing rate and control room operator occupancy rate changes resulting from the steaming timeline extension (using the Regulatory Guide 1.183 designated values). There are no changes to the dose consequence calculation methodology associated with this activity.

With an asymmetric reactor coolant system (RCS) cooldown following a MSLB outside containment, the time required to place the residual heat removal (RHR) system in service (terminating releases from the intact steam generators) and the time required to cool the RCS to below 212°F is longer than the times credited in the current MSLB dose consequence analysis. The termination of steam releases following a MSLB outside of containment could require as much as 46.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, based on application of the most restrictive 8°F per hour cooldown rate. The slower RCS cooldown rate is to ensure that the inactive faulted loop (which is not being cooled by releasing steam) does not become uncoupled from the rest of the RCS.

As a result of this increased steaming duration, dose consequences for the control room operator and at the low population zone (LPZ) increase for both the pre-accident and the concurrent iodine spike cases. This evaluation addresses the increases in the LPZ and control room operator dose consequences for a MSLB outside containment.

Summary of Evaluation:

The LPZ and control room operator dose consequence increases for a MSLB outside of containment (both pre-accident iodine spike and concurrent iodine spike cases) are less than 10 percent of the margin to the applicable regulatory limit (either 10 CFR 50.67 or 10 CFR 50 Appendix A GDC-19) and are, therefore, defined as minimal.

There are no MSLB dose consequence increases associated with the exclusion area boundary pre-accident iodine spike and the concurrent iodine spike doses. This is because those consequences result from the worst 2-hour dose at the site boundary, which occurs from 4 to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

The maximum dose consequence occurs in the concurrent iodine spike control room operator dose consequence, which is proposed to increase from 1.655 Roentgen equivalent man (rem) total effective dose equivalent (TEDE),

to 1.972 rem TEDE, relative to the 5 rem TEDE regulatory limit. This results in a percent of margin increase equivalent to 0.091 or 9.1 percent of margin, which is defined as minimal according to the 10 CFR 50.59 methodology because the increase is less than 10 percent of margin. The concurrent iodine spike dose consequence for the LPZ increases from 0.64 rem TEDE to 0.80 rem TEDE, resulting in 0.086 or 8.6 percent of margin.

The increase in the LPZ and control room operator dose consequences for a MSLB outside containment does not meet any of the 10 CFR 50.59(c)(2) criteria; therefore, a license amendment is not required.

Attachment L-25-049 Page 2 of 6

Title:

Site Boundary and Control Room Doses based on Core Uprate and Alternative Source Term (AST) Methodology following a) a Locked Rotor Accident; b) a Loss of AC Power Accident at Unit 2 Activity

Description:

The proposed activity is to develop Beaver Valley Power Station, Unit 2 (BVPS-2), specific dose consequences at the site boundary and control room following a locked rotor accident (LRA) and a loss of alternating current (AC) power (LACP) accident.

A BVPS-2 LRA, resulting in up to 20 percent of fuel cladding failure, should not credit radiological release termination at 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> (by placing RHR in service), as has been credited in the past. It may take up to 13.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> to cooldown and depressurize the RCS, place RHR in service, and terminate the steam release to atmosphere following a LRA with a postulated loss of offsite power. This is because the procedures used following a LRA require boration to shutdown margin to be completed prior to RCS cooldown initiation, which delays commencement of RCS cooldown. Then, placing RHR in service after cooling down requires a few hours prior to final termination of the contaminated steam release.

The BVPS-2 specific dose consequences incorporate the changes to the steaming duration discussed above, implementation of the bounding BVPS-2 main steam safety valve / atmospheric dump valve (MSSV/ADV) atmospheric dispersion (X/Q) factor (instead of the more limiting Beaver Valley Power Station Unit 1 (BVPS-1)

LRA X/Q value in the common unit calculation) and offsite breathing rate changes in compliance with the Regulatory Guide 1.183 designated values, which apply only after the steam release duration exceeds 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

There are no changes to the dose consequence calculation methodology associated with this change. The loss of non-emergency AC power (LACP) dose consequences remain bounded by the LRA dose consequences and is not evaluated for any specific dose consequence change. The X/Q factor change is appropriate because BVPS-1 no longer postulates any fuel damage in the event of a LRA, no rods entering departure from nucleate boiling.

As a result of this increased steaming duration and atmospheric dispersion changes, BVPS-2 LRA calculated dose consequences change. This evaluation addresses the increases in the low population zone (LPZ) dose consequences for a LRA.

Summary of Evaluation:

The LPZ dose consequence increases for a BVPS-2 LRA are less than 10 percent of the margin to the applicable regulatory limit (either 10 CFR 50.67 or 10 CFR 50 Appendix A GDC-19) and are, therefore, defined as minimal.

The LRA dose consequence at the exclusion area boundary (EAB) stayed the same because the worst 2-hour dose at the site boundary still occurs from 6 to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> (prior to offsite breathing rate decrease). The control room operator dose consequence actually decreased because the reduced X/Q factor from the BVPS-2 MSSV/ADV to the control room intakes more than compensates for the increased steaming duration.

The maximum dose consequence increase occurs in the LPZ dose, which is proposed to increase from 0.343 rem TEDE to 0.553 rem TEDE, relative to the 2.5 rem TEDE regulatory limit. This results in a percent of margin increase equivalent to 0.0974 or 9.741 percent of margin, which is defined as minimal according to the 10 CFR 50.59 methodology because the increase is less than 10 percent of margin to the regulatory limit. No other dose consequence increases are associated with the proposed changes.

The increase in BVPS-2 dose consequences for a LRA does not meet any of the 10 CFR 50.59(c)(2) criteria; therefore, a license amendment is not required.

Attachment L-25-049 Page 3 of 6

Title:

Extend the Frequency as Listed in LRM [Licensing Requirements Manual] Table 3.3.6-2 for the Calibration Interval for the Specified Seismic Monitoring Instrumentation Activity

Description:

The proposed activity revises BVPS-2 LRM Table 3.3.6-2, Seismic Monitoring Instrumentation Surveillance Requirements as follows:

1. The Channel Calibration for the Triaxial Time-History Accelerographs will be performed at a two refueling outage (36 month) frequency instead of the current required refueling outage (18 month) frequency.

2. The Channel Operational Test for the Response Spectrum Analyzer will be performed at a two refueling outage (36 month) frequency instead of the current required refueling outage (18 month) frequency.

Summary of Evaluation:

Seismic instrumentation is provided to monitor input motion and behavior of critical elements of BVPS-2 under earthquake conditions in accordance with Regulatory Guide 1.12, Revision 1. The instrumentation includes three triaxial time-history accelerographs that are part of the Condor System, three triaxial time-history accelerographs that are part of the Etna System, and a seismic instrumentation panel in the control room. The seismic instrumentation panel consists of recorders and an interface panel for the Condor System, a power supply, a plotter, seismic instrument annunciation and a response spectrum analyzer. The Etna System has individual chargers for the three triaxial time-history accelerographs.

Each triaxial time-history accelerograph contains a force balance transducer with three accelerometers mounted on mutually orthogonal axes. The Condor System accelerometers are the transducer type, capable of recording a maximum acceleration of 1.0 gravity (g) full scale. Recording of the electric signals from the acceleration is by a data acquisition system in the seismic instrumentation panel in the control room. Recording of the Condor System accelerometers is initiated at a trigger point less than or equal to 0.02 g in the horizontal or vertical direction except the accelerograph located on the containment operating floor at elevation 767 feet. This accelerograph has a trigger point of 0.6 g in either direction.

The Etna System triaxial time-history accelerographs are not connected to the seismic instrumentation panel in the control room. These accelerographs include a recorder, an internal triaxial fore-balanced accelerometer, and a built-in timing system. As the sensors pick up ground acceleration or velocity signals, the recorder continuously monitors those signals to see if they satisfy seismic event detection criteria. When the signals satisfy these criteria, the recorder stores event data for later retrieval. A laptop computer is used to download the information from the Etna accelerographs, which can then be connected to the seismic instrumentation panel to evaluate and plot the data.

The triaxial time-history accelerographs, the response spectrum analyzer and the other components of the seismic instrumentation panel have no impact on plant control, no impact on an accident response, no impact on the consequences of any accident described in the Updated Final Safety Analysis Report (UFSAR), and no impact on the analysis methodology used in the design of the plant. The only connection to the remainder of the plant is the control room annunciator system. Annunciator A10-5H will annunciate from the control room seismic panel fed from the Condor triaxial time-history accelerographs upon a seismic event that exceeds a setpoint or if there is a failure of the system. The operators respond to this alarm in accordance with site procedures to observe indications and obtain data on a seismic instrumentation panel located in the control room. This response is unchanged due to extending the surveillance frequencies. Therefore, changing the calibration period will not have an adverse effect on any aspect of the plant as described in the BVPS-2 UFSAR.

Extending the calibration interval will slightly raise the probability that an instrument may not be accurate when called upon to function. However, a review of the calibration history shows that the instruments have been found to be functional and reliable.

Attachment L-25-049 Page 4 of 6 Due to the Covid pandemic, system calibrations for the Condor System and Etna System were performed three years apart at both units. For the Condor System, only minor out of tolerance conditions for offset values were found that were well within the required tolerance once the sensors are installed. This had no effect on the function of the seismic instrumentation systems. For the Etna System, no issues were found with calibrations performed at the 36-month frequency.

Therefore, based on the surveillance history of the BVPS-2 seismic monitoring instrumentation and the limited history of performing surveillance calibrations at a 36-month frequency, there is a high confidence that the instruments will be accurate despite the longer calibration period.

The surveillance calibration frequency extension to 36 months does not meet any of the 10 CFR 50.59(c)(2) criteria; therefore, a license amendment is not required.

Attachment L-25-049 Page 5 of 6

Title:

Flushing Rocker Arm Lube Oil Reservoir from the EDG [Emergency Diesel Generator] Lube Oil Sump Activity

Description:

This activity provides procedural guidance to mitigate the concern to periodically manually drain the BVPS-2 EDG rocker arm lube oil reservoir during EDG operation. This procedure is a compensatory measure identified in a follow-up operability determination (FOD), consistent with Nuclear Regulatory Commission (NRC) Inspection Manual (IM) 0326, Section 6.08 and the site procedure on operability determinations and functional assessments.

The intent of the action is to maintain required fuel oil dilution of the rocker arm lube oil reservoir within the vendor recommended limit of 5 percent at the current fuel oil leakage rate obtained from EDG test data. This action supports the 30-day mission time of the EDG.

An EDG rocker arm lube oil sample showed a step change in rocker arm lube oil dilution from an intrusion of fuel oil resulting in dilution values of 1.9 percent (taken on April 19, 2023) to 3.7 percent (taken on June 28, 2023).

The fuel oil concentration limit for the EDG lube oil system is 6.1 percent of the lube oil volume to prevent lube oil viscosity from becoming too low and will also ensure that the flash point of the oil mixture does not become low enough to ignite in the engine. As it was unable to be shown that the dilution limit would not be reached with the current fuel oil inleakage, a compensatory action of manually draining the diluted rocker arm lube oil reservoir, periodically, to allow the auto-fill feature from the main lube oil system reservoir to enact more frequently, is developed to maintain lube oil viscosity and dilution requirements.

Summary of Evaluation:

The EDG lubrication system as described in BVPS-2 UFSAR Section 9.5.7.2 provides essential lubrication to the components of the EDG. The engine lubrication system is integral with the engine. Included in the lubrication oil system for each engine is a rocker-arm lube oil sub-system with its own smaller reservoir and automatic make up feature.

Technical Specification (TS) 3.8.3 Bases states the EDG lubrication system is designed to provide sufficient lubrication to permit proper operation of its associated EDG under all loading conditions. The system is required to circulate the lube oil to the diesel engine working surfaces and remove excess heat generated by friction during operation.

TS Surveillance Requirement (SR) 3.8.3.2 ensures that sufficient lube oil inventory is available to support at least 7 days of full load operation for each EDG. The lube oil inventory equivalent to a 7-day supply is 330 gallons (per TS SR Bases 3.8.3.2). The required inventory for each EDG is confirmed by verifying that the lube oil volume of 330 gallons (six 55-gallon oil drums) is available in storage, for each EDG. This supply is sufficient to allow the operator to replenish lube oil from outside sources.

The procedure guidance permits Operations personnel to manually flush the rocker arm lube oil reservoir for the EDG by lowering level and allowing the reservoir to refill from the EDG lube oil sump. The procedure specifies a limit of 10 gallons per instance of draining. Adequate margin exists in the TS Bases EDG lube oil inventory requirement to permit the additional lube oil loss from draining up to 10 gallons per day, which is more than the calculated volume required to be flushed to maintain the lube oil below the maximum dilution value of 6.1 percent.

At the existing leakage rate extrapolated from the data taken during the test run from July 15, 2023, the action will maintain the fuel oil concentration under 5 percent, which is the maximum fuel oil concentration recommended by EDG vendor and industry documentation. The analyzed limit of 6.1 percent provides additional margin.

This compensatory action will ensure the lube oil viscosity and dilution limits are met and maintain EDG operability without challenging TS surveillance requirements. Proceduralized filling and draining at a frequency based on conservative assumptions ensures that the increase in likelihood of a failure of the EDG rocker arm lube oil system is minimal. The procedural guidance does not meet any of the 10 CFR 50.59(c)(2) criteria; therefore, a license amendment is not required.

Attachment L-25-049 Page 6 of 6

Title:

Revise BVPS-1/2 Licensing Requirement Surveillance 3.3.3.2 for Meteorological Monitoring Instrumentation Channel Calibration Activity

Description:

An engineering change upgraded the instruments installed on the meteorological (MET) tower, which is a 500-foot guyed tower located approximately 3,600 feet northeast of BVPS-1, as described in BVPS-1 UFSAR Appendix 2A and Figure 2A.3-1. The MET system instruments are mounted on the MET tower. The system has two independent trains (primary and redundant) with instruments mounted on each of three elevations: 35 feet (ft),

150 ft, and 500 ft.

The primary instrument train consists of wind speed/direction sensors and temperature sensors mounted on the 35 ft, 150 ft, and 500 ft elevations. The redundant instrument train also consists of wind speed/direction sensors and temperature sensors mounted on the 35 ft, 150 ft, and 500 ft elevations. A precipitation gauge is mounted at ground level. Each train contains one datalogger for the primary channels and for the redundant channels.

The purpose of the MET tower is to provide inputs for the BVPS meteorological measurement program in order to calculate site X/Q factors as described in more detail in BVPS-1 UFSAR Section 2.2.4 and Appendix 2A, as well as BVPS-2 UFSAR Sections 2.3.3 and 2.3.4. The program meets the requirements of Regulatory Guide 1.23, Revision 0, and Regulatory Position C.1.1 of Regulatory Guide 1.145, Revision 1. The actual methodology used to calculate such factors is not affected; the meteorological tower parameters provide inputs for such calculations.

The current BVPS-1 and BVPS-2 LRM Surveillance 3.3.3.2 requires channel calibration be performed every 184 days. The new instruments do not require calibration of this frequency; therefore, the LRM Surveillance (LRS) will be revised to once every 2 years (24 months) calibration based on vendor recommendations. A new surveillance for a functional check of the instruments will be added at an annual (12 month) frequency. The functional check may be waived if a calibration is performed. A new definition of FUNCTIONAL CHECK will also be added to the LRM. The original BVPS safety evaluations only reference the Regulatory Guide in discussing the installation of the meteorological tower and the overall use of meteorological data to determine site atmospheric dispersion. No specific mention is made of calibration frequency.

The scope of this evaluation is limited to the calibration frequency of the instrument channels. Instrument replacement was performed under a separate engineering change.

Summary of Evaluation:

MET instrumentation is used to obtain information required for a valid estimation of atmospheric diffusion at the site in accordance with Regulatory Guide 1.23 Revision 0 (previously known as Safety Guide 23) to which both units at BVPS are licensed. Regulatory Guide 1.23 Section C.5 states in part instruments should be calibrated at least semiannually. The proposed change will deviate from the Regulatory Guide calibration frequency.

The MET system is independent of any plant control systems, structures, and components important to safety, and fission product barriers. It is not an accident initiator as described in the UFSAR and cannot cause an accident of a different type. The MET system has no impact on the consequences or frequency of an accident.

Data from the MET system is used as an input to dose projection in the event of a radiological release. The evaluation methodology used in the dose projection remains unchanged.

Extending the calibration interval will slightly raise the probability that an instrument may not be accurate when called upon to function; however, there is high confidence that they will maintain accuracy despite a longer calibration period. There is not a more than minimal increase in the likelihood of an occurrence of a malfunction.

The revised surveillance frequency does not meet any of the 10 CFR 50.59(c)(2) criteria; therefore, a license amendment is not required.