Text

Proposed License Amendment Request Re Alternate Control Rod Position Monitoring
	ML15041A667
Person / Time
Site:	North Anna
Issue date:	02/04/2015
From:	Mark D. Sartain; Virginia Electric & Power Co (VEPCO)
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	15-040
	Download: ML15041A667 (30)
	v • d • e

VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 February 4, 2015 10 CFR 50.90 U. S. Nuclear Regulatory Commission Serial No.: 15-040 Attention: Document Control Desk NAPS/JHL: RO Washington, DC 20555-0001 Docket Nos.: 50-338/339 License Nos.: NPF-4/7 VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 PROPOSED LICENSE AMENDMENT REQUEST ALTERNATE CONTROL ROD POSITION MONITORING Pursuant to 10CFR50.90, Virginia Electric and Power Company (Dominion) is submitting a license amendment request to revise the North Anna Power Station Units 1 and 2 Technical Specifications (TS). The amendment revises the Actions of Technical Specification 3.1.7, Rod Position Indication, to provide an additional monitoring option for an inoperable control rod position indicator. Specifically, the proposed changes would allow monitoring of control rod drive mechanism (CRDM) stationary gripper coil voltage every eight hours as an alternative to using the movable incore detectors every eight hours to verify control rod position. provides a discussion of the proposed change. The marked-up and proposed TS pages are included in Attachments 2 and 3, respectively. The TS Bases changes are provided for NRC information only in Attachment 4.

We have evaluated the proposed amendment and have determined that it does not involve a significant hazards consideration as defined in 10CFR50.92. The basis for this determination is included in Attachment 1. We have also determined that operation with the proposed change will not result in any significant increase in the amount of effluents that may be released offsite or any significant increase in individual or cumulative occupational radiation exposure. Therefore, the proposed amendment is eligible for categorical exclusion from an environmental assessment as set forth in IOCFR51.22(c)(9). Pursuant to 10CFR51.22(b), no environmental impact statement or environmental assessment is needed in connection with the approval of the proposed change. The proposed TS change has been reviewed and approved by the Facility Safety Review Committee.

Dominion requests an expedited review of the proposed change to limit the wear on the movable incore detection system, which is currently being operated every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months to comply with the Actions of 3.1.7.A for an inoperable control rod position indicator.

Dominion will implement the change within 30 days of approval.

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Serial No.15-040 Docket Nos. 50-338/339 Page 2 of 3 Should you have any questions or require additional information, please contact Mr. Jay Leberstien at (540) 894-2574.

Respectfully, Mark D. Sartain Vice President - Nuclear Engineering Commitments contained in this letter: None Attachments:

1. Discussion of Change

2. Marked-up Technical Specifications Pages

3. Proposed Technical Specifications Pages

4. Marked-up Bases Pages (for information only)

COMMONWEALTH OF VIRGINIA )

)

COUNTY OF HENRICO )

The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Mr. Mark D. Sartain, who is Vice President - Nuclear Engineering, of Virginia Electric and Power Company. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that company, and that the statements in the document are true to the best of his knowledge and belief.

Acknowledged before me this L4.'- day of !Anox ,2015.

My Commission Expires: -. Jw 31, ZoWt.

Notary Public WA N DýA 0. CRAFT- -

Notary Public I M Commonweptth of Virginia iReg.

My Commission L - ?1

'52.0495 re,;,jo nuary 31, 20&l"

Serial No.15-040 Docket Nos. 50-338/339 Page 3 of 3 cc: U.S. Nuclear Regulatory Commission - Region II Marquis One Tower 245 Peachtree Center Avenue, NE Suite 1200 Atlanta, GA 30303-1257 State Health Commissioner Virginia Department of Health James Madison Building - 7 th floor 109 Governor Street Suite 730 Richmond, VA 23219 Dr. V. Sreenivas NRC Project Manager - North Anna U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 G-9A 11555 Rockville Pike Rockville, MD 20852-2738 Ms. Karen Cotton-Gross NRC Project Manager - North Anna U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 G-9A 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector North Anna Power Station

Serial No.15-040 Docket Nos. 50-338/339 Attachment I DISCUSSION OF CHANGE Virginia Electric and Power Company (Dominion)

North Anna Power Station Units I and 2

Serial No.15-040 Docket Nos. 50-338/339 Page 1 of 13 Attachment 1 TABLE OF CONTENTS 1.0

SUMMARY

DESCRIPTION 2.0 DETAILED DESCRIPTION

3.0 TECHNICAL EVALUATION

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria 4.2 Precedent 4.3 Significant Hazards Consideration 4.4 Conclusions

5.0 ENVIRONMENTAL CONSIDERATION

S

6.0 REFERENCES

Serial No.15-040 Docket Nos. 50-338/339 Page 2 of 13 Attachment 1 1.0

SUMMARY

DESCRIPTION The proposed change would revise the North Anna Units 1 and 2 Technical Specification (TS) 3.1.7, "Rod Position Indication". Currently, in the event that a single rod position indicator is inoperable, Action A.1 of TS 3.1.7 requires the verification of rod position by use of the movable incore detectors every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months . This amendment request proposes a revision to allow the position of the rod to be monitored by a means other than movable incore detectors. Monitoring of the control rod drive mechanism (CRDM) stationary gripper coil voltage will confirm rod position has not changed, once verified by the movable incore detectors. This change would minimize excessive use and wear on the movable incore detector system. The alternate monitoring would be effective until repair of the indication system can be completed, but not longer than one operating cycle.

In addition, it is proposed that an asterisk associated with a cycle specific requirement in Condition D of TS 3.1.7 and the associated note be deleted since North Anna Unit 2 is no longer in Cycle 22.

2.0 DETAILED DESCRIPTION The proposed change to TS 3.1.7 will add new actions that allow the use of an alternative rod position monitoring method. Actions A.3.1 and A.3.2 will be incorporated to provide for the alternative monitoring. The new requirements are as follows:

Action A.3.1 Verify the position of the rod with the inoperable rod position indication indirectly by using the movable incore detectors.

A.3.1 Completion Time:

Once within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months of condition entry (or rod control system indication of potential rod movement) and every 31 days thereafter Action A.3.2 Review the parameters of the rod control system for indications of rod movement for the rod with an inoperable position indicator.

A.3.2 Completion Time Once within 16 hours1.851852e-4 days 0.00444 hours 2.645503e-5 weeks 6.088e-6 months and every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter A Note is added that will apply to the new Actions A.3.1 and A.3.2. This note describes the limitations for use of these new provisions. The following is the wording of the Note:

Serial No.15-040 Docket Nos. 50-338/339 Page 3 of 13 Attachment 1 Rod position monitoring by Actions A.3.1 and A.3.2 may be applied to only one inoperable rod position indicator and shall only be allowed until an entry into MODE 5.

This ensures that the alternate monitoring for one inoperable rod position indicator can only be in place at most one operating cycle or until the plant enters Mode 5 for a forced outage of sufficient duration, whichever comes first.

The proposed change will provide an alternative to the use of the movable incore detectors every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months for an extended period of time until repairs can be completed.

Continued implementation of TS 3.1.7 Action A.1 would result in at least 90 operations of the incore detector system per month and may result in excessive wear on the system. Although wear of the incore detector system does not pose a significant reduction in the margin of safety, excessive wear could result in a loss of system functionality. This could lead to the inability to complete required surveillances, which could lead to a required plant power reduction and/or shutdown. This vulnerability has been recognized at North Anna based on actual rod position indicators concerns and alternate solutions have been evaluated based on prior industry operating experience.

A marked-up copy and a typed page of the proposed Technical Specification are provided in Attachment 2 and Attachment 3, respectively. A marked-up copy of the Bases is provided in Attachment 4 for information only.

3.0 TECHNICAL EVALUATION

TS 3.1.7 ensures the rod position indicators are capable of determining the position of the control or shutdown rods. Electrical failures may cause a control rod to become inoperable, to become misaligned from its group, or to be excessively inserted. Control rod inoperability, misalignment or rod insertion in excess of limits may violate the input assumptions of a design basis accident. Limits on control rod alignment, insertion and operability have been established and all rod positions are monitored and controlled during shutdown and power operation to ensure that the safety analysis assumptions are satisfied.

The axial position of control or shutdown rods is indicated by two separate and independent systems: the Bank Demand Position Indication System (commonly called group step counters) and the Rod Position Indication (RPI) System. The Bank Demand Position Indication System counts the pulses from the Rod Control System that move the rods. There is one step counter for each group of 4 control rods. Individual rods in a group all receive the same signal to move and should, therefore, all be at the same position indicated by the group step counter for that group. The Bank Demand Position Indication System is considered highly precise (+/- 1 step or +/- 5/8 inch).

The RPI System provides an accurate indication of actual control rod position, but at a lower precision than the step counters. This system is based on inductive analog signals from a series of coils spaced along a hollow tube. The analog signal is

Serial No.15-040 Docket Nos. 50-338/339 Page 4 of 13 Attachment 1 produced for each rod by a linear variable differential transformer. Direct continuous readout of each rod is provided by individual meter indications on the Control Room benchboard. The RPI System is capable of monitoring rod position within at least +/- 12 steps.

Operators use the RPI system to monitor the position of the control rods to establish that the plant is operating within the Technical Specifications, which ensures the safety analysis assumptions are preserved. The noted Updated Final Safety Analysis Report (UFSAR) sections below discuss the design and function of the RPI System. Key analysis assumptions for rod position include verification that the control rods are operating within the group sequence and overlap and maintain operation above the rod insertion limits - which ensures adequate Shutdown Margin (SDM).

3.1.9.2 "Design Criteria" 4.2.3.5 "Instrumentation Applications" 7.7, "Plant Control System" 15.0, "Accident Analysis" Although the RPI system is a primary tool for verifying TS requirements for control rod position parameters, TS 3.1.7 allows for verification of rod position via the movable incore detector system in the event an individual control rod position indicator is inoperable. The verification of control rod location can also be monitored via tracking of the CRDM stationary gripper coil voltage on the affected control rod. Simply put, provided the TS required control rod positioning Limiting Condition for Operation (LCO) and Surveillance are satisfactorily performed, there is no impact to the safety analysis assumptions. The safety analysis does not designate the manner in which parameters are verified; it only requires those parameters meet certain criteria (TS LCO, Core Operating Limits Reports (COLR) limit, TS surveillance requirement (SR), etc).

Should a technical problem arise with RPI system components inside containment, limited actions can be taken while the unit is operating. This is due to the adverse radiological and temperature environment that exists near the reactor head area.

Repairs to the rod position indicator coils would require removal of the reactor head missile shield assembly that provides a duct system for the control rod drive mechanism cooling air flow. Inspection access doors are provided, however repair of the rod position indicator coil cannot be performed with the head assembly package in place.

Repairs cannot be performed safely until the unit is in cold shutdown conditions (MODE 5). While troubleshooting and limited repairs can be performed in MODES 1 - 4, these are not encompassing of all credible failure modes. Dominion considers the proposed monitoring of the status of the CRDM stationary gripper coil voltage to be a valid means of monitoring that the rod position has not changed once the position is confirmed through the use of the movable incore detectors. Dominion plans to monitor the CRDM stationary gripper coil voltage until unit entry into a Mode 5 outage of sufficient duration when repairs to the system can be safety implemented or for the remainder of the operating cycle, whichever comes first. The monitoring of the position in this manner also has an added benefit that it will alleviate a concern regarding the potential for

Serial No.15-040 Docket Nos. 50-338/339 Page 5 of 13 Attachment 1 excessive wear of the incore monitoring system due to the use of the incore detectors every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months to comply with Action A. 1 of TS 3.1.7.

In evaluating the requested change, the following operational events impacted by a dropped rod or rod misalignment were considered:

" Dropped Rod or Rod Misalignment During Power Operation

" Dropped Rod or Rod Misalignment During Reactor Startup

" Reactor Trip

" Shutdown Margin Dropped Rod or Rod Misalignment During Power Operation A drop of a single control or shutdown rod is detectable by means other than the position indication system. UFSAR Section 15.2.3.2 states that a dropped / misaligned rod is detected by the following systems / variables:

Dropped Rod

1. Sudden drop in the core power level as seen by the Nuclear Instrumentation System,

2. Asymmetric power distribution as seen on out-of-core neutron detectors or core exit thermocouples,

3. Rod at bottom signal,

4. Rod deviation alarm, or

5. Rod position indication.

Misaligned Rod

1. Asymmetric power distribution as seen on out-of-core neutron detectors or core exit thermocouples,

2. Rod deviation alarm, or

3. Rod position indication.

Aside from the UFSAR, other independent indications of a dropped rod may also be available by the observation of the high negative flux rate trip alarm. A large negative reactivity insertion corresponding to the reactivity worth of a single dropped rod may also cause a detectable change in RCS parameters including calculated reactor power and average RCS temperature and core delta-T.

A rod misalignment may also be detectable by other monitoring systems such as axial flux difference, a power range detector channel average flux deviation alarm and various rod control cabinet alarms, depending on the severity of the misalignment.

Based on these diverse indications, operator actions will be initiated that are not solely dependent on the status of the RPI system. For the infrequent instances when control rod bank movement is required during power operation (e. g., SR 3.1.4.2 for control rod

Serial No.15-040 Docket Nos. 50-338/339 Page 6 of 13 Attachment 1 operability), a determination of rod position will be made by using the movable incore detector system in accordance with plant procedures.

Considering the available indications and alarms, the increase in the likelihood of an undetected dropped rod or misalignment is considered to be negligible while the alternate monitoring is used in conjunction with the other available dropped rod and misalignment parameter indications.

Dropped Rod or Rod Misalignment During Reactor Startup For a situation where there is an unplanned outage that does not result in an entry into a Mode 5 outage of sufficient duration and repairs are not possible in a higher Mode, North Anna plans to use alternate monitoring. Since the movable incore detectors cannot be used to determine rod position until sometime after escalating into Mode 2 when neutron flux increases to sufficient magnitude, an alternate method may be used to verify that the rod is fully withdrawn by monitoring CRDM traces. Rod position verification using this method will permit startup and entry into Mode 2. As a second diverse check, the movable incore detectors will be used to verify rod position when neutron flux increases to a sufficient magnitude. Following verification that the rod is withdrawn, a rod misalignment would be detectable by means other than the RPI system (CRDM trace monitoring, axial flux difference, power range detector channel average flux deviation alarm and various rod control cabinet alarms, etc). The required operator actions would not be dependent on the status of the individual rod position indication from the RPI system. Therefore, the increase in the likelihood of an undetected dropped rod or misalignment during reactor startup is considered to be negligible.

Reactor Trip Following a reactor trip, the position indication system is used to verify that all rods have fully inserted. Boration is required if one or more rods fails to fully insert. If it cannot be verified with RPI System indication that all rods are on the bottom, then procedure ES-0. 1, "Reactor Trip Response," currently requires boration to account for each rod not fully inserted.

Shutdown Margin Shutdown Margin in Modes 1 and 2 with Keff > 1.0 is ensured by verifying that control bank and shutdown bank rods are within limits specified in the COLR. The rod insertion limit (RIL) circuit is designed to provide operators with a continuously calculated insertion limit for each of the control banks that is variable with coolant loop average differential temperature (delta-T) power. The RIL circuitry provides alarms to assist operators in ensuring operation above the RIL. The RIL circuit performs its function by receiving control bank position pulse data from the rod control system. It compares this data to the calculated limit that is determined by reactor power as measured from delta-T. The rod insertion limits ensure that adequate shutdown margin exists to

Serial No.15-040 Docket Nos. 50-338/339 Page 7 of 13 Attachment 1 shutdown the reactor at any time and condition in the life of the operating cycle. The RIL monitoring circuit is independent of the rod position indication circuit. Inoperability of the rod position indicator has no impact on the RIL monitoring system and therefore the inoperable rod position indicator has no impact on the ability of operators to verify Shutdown Margin via the RIL monitoring circuitry. The proposed alternate method to monitor CRDM stationary gripper coil voltage for a control rod with an inoperable rod position indicator will provide assurance that the rod position has not changed and remains within the allowed misalignment with the group step counter demand position for the affected control rod and the control rod bank insertion limits of TS 3.1.5 and 3.1.6.

Shutdown Margin in Mode 2 with Keff < 1 is determined in accordance with TS 3.1.1 by comparing the RCS boron concentration to a shutdown margin requirement curve.

While in Mode 2, the RPI system is relied upon to determine rod position. While a single rod position indicator remains out of service, rod position cannot be easily determined. Accordingly, the RCS boron concentration requirements will be increased to consider an allowance for the withdrawn worth of a control rod with an inoperable position indicator. Procedure ES-0.1 currently requires boration to account for any rod that cannot be verified to be fully inserted. Shutdown Margin Calculations performed in procedures 1-PT-10 and 2-PT-10, Shutdown Margin Determination and 1-PT-10.1 and 2-PT-10.1, Shutdown Margin Determination at Power with Inoperable or Misaligned Control Rods will require revision to account for the rod with inoperable indication in addition to the most reactive rod assumed to be fully withdrawn.

In Modes 3, 4, and 5, the RPI system group step counters are relied upon to determine rod position in accordance with Technical Requirement 3.1.3. In Modes 3, 4, and 5, the individual rod position indicators are not used to determine shutdown margin.

Adequacy of the Proposed Monitoring The parameter monitored for a control rod or shutdown rod with an inoperable position indicator will be the CRDM stationary gripper coil voltage. The control rods are held in place by energized stationary gripper coils. The control rod cannot be moved without de-energizing the CRDM stationary gripper coil. The CRDM stationary gripper coil voltage will be monitored by a temporary digital recorder. There will be an alarm capability to inform the control room operators that the rod moved based on a change in CRDM stationary gripper coil voltage. Operators will verify and record the CRDM stationary gripper coil voltage in accordance with the Completion Time of the proposed Required Action A.3. This will allow for trending and historical data retrieval.

Since the monitoring will be performed by Operations, it is proposed to continue the monitoring to determine if the CRDM stationary gripper coil voltage has changed state on a once every 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months basis. Should the parameters of the coils of the monitored rod indicate movement, a determination of the position of the rod will be made using the movable incore detectors within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months . This timeframe is consistent with existing TS 3.1.7 Action A.1. Since verification with incore detectors is performed within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months ,

Serial No.15-040 Docket Nos. 50-338/339 Page 8 of 13 Attachment 1 continued monitoring of rod control system parameters is not required until 16 hours1.851852e-4 days 0.00444 hours 2.645503e-5 weeks 6.088e-6 months after rod movement is identified. In practice, this would occur 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months after verification is performed with movable incore detectors.

To provide a verification of the reliability of the alternate monitoring, rod position is verified by movable incore monitoring every 31 days. This frequency minimizes use of the movable incore monitoring system and can be performed concurrently with existing surveillance requirements for Hot Channel Factors.

A Note has been added to TS 3.1.7 to ensure that the alternate monitoring requirements are not used as a long term means of verifying rod position. The intended use of this alternate is to allow for monitoring until plant entry into a Mode 5 outage of sufficient duration to safely repair the RPI indication. This ensures that at most, the alternate is used for the remainder of the operating cycle.

Compliance with either Action A.1 or the proposed Action A.3 will result in the verification of the position of the affected rod within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months by use of the movable incore detectors. Based on available information, the monitoring of the CRDM stationary gripper coil voltage of the inoperable control rod as defined in proposed Action A.3 will be initiated.

Impact on Indication and Alarms The following table provides a summary of the indications and alarms and how they are affected by the inoperable RPI for a control rod or shutdown rod.

Affected by Modified Function IndicationlAlarm Normal Operation Operation Individual Rod Control Room Provides analog rod This indication will be Position Indicator Benchboard position reading for control unavailable and considered rod or shutdown rod out-of-service for the control rod or shutdown rod with the inoperable position indication.

Rod Bottom Control Room Provides indication that all This indication will be Indication Benchboard rods are on the bottom unavailable and considered out-of-service for the control rod or shutdown rod with the inoperable position indication.

RPI Rod Bottom/ Annunciator This annunciation is The ability of the control rod or Rod Drop Window A-G2 actuated by any rod shutdown rod to actuate this Annunciation position indicating channel annunciation will be disabled.

being < 20 steps and for Other control rods or control and shutdown banks shutdown rods with operable being > 35 steps indicators will actuate this annunciator.

Serial No.15-040 Docket Nos. 50-338/339 Page 9 of 13 Attachment 1 Affected by Modified Function IndicationlAlarm Normal Operation Operation Bank A, B, C and D Annunciator For Control Banks A and B, This indication is driven by the Low / Low-Low Windows A-H1, A- the annunciation is actuated control rod drive system and is Limit Annunciation H2, A-H3, and A-H4 at a low limit < 222 steps therefore, unaffected by the and the low-low limit < 212 inoperable rod position steps. For Control Bank C, indicator.

the annunciation is actuated for a low-low limit established by the COLR and the low limit is the low-low limit + 3 steps. For Control Bank D, annunciation is actuated for a low-low limit established by the COLR and the low limit is the low-low limit + 10 steps.

Rod Control Urgent Annunciator Window This annunciation is This indication is driven by the Failure A-D1 actuated for any conditions control rod drive system and is Annunciation that prevents proper rod therefore, unaffected by the motion or is indicative of inoperable rod position potentially undesirable rod indicator. This annunciator is motion. used in conjunction with the local alternate monitoring to identify unintended rod motion.

Any CRDM coil current that does not match demand will cause the alarm.

Computer Alarm Window A-F1 This annunciation will This indication is driven by the Rod Deviation / actuate when there is a control rod drive system and is Sequence Alarm dropped rod and a rod affected by the inoperable rod position error signal or position indicator.

indication fault as indicated by any of the following alarms:

- Movement of any Control Bank with the Shutdown Banks less than fully withdrawn

- Any improper control rod overlap sequence of control rod bank positions not 128 steps apart for partially withdrawn banks.

- Any rod position indicating > 10 step deviation from bank.

- Any rod position indicating > 12 steps deviation from bank.

Any rod position indicating > 24 steps deviation from bank,

Serial No.15-040 Docket Nos. 50-338/339 Page 10 of 13 Attachment 1 Affected by Modified Function Indication/Alarm Normal Operation Operation Computer Alarm below 50% power.

Rod Deviation / - > 12 steps deviation for_>

Sequence Alarm 30 minutes total (continued) accumulated time in the previous 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period, below 50% power.

> 12 steps deviation for_>

60 minutes total accumulated time in the previous 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period, below 50% power.

Compensatory Measures To compensate for inoperable indication, the alternate monitoring system will monitor and record CRDM stationary gripper coil voltage. Since verification with the incore movable detector system is required within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months of any rod motion, this provides a level of assurance greater than or equal to existing TS 3.1.7 Action A.1.

Rod movement of > 24 steps since the last determination of rod position is a separate entry condition of TS 3.1.7. Required Action C.1 requires verification of position of rods with inoperable position indicators using movable incore detectors within 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months if rod movement of > 24 steps in one direction has been performed since the last determination of rod position. If this cannot be performed, then Required Action C.2 states that Thermal Power must be reduced to < 50% Rated Thermal Power. This condition and required actions remain unaffected by the alternate indication.

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements / Criteria The objectives of the rod control system and rod position indication system are to ensure that control rod alignment and insertion limits are maintained. Operators use the RPI system as well as Rod Control System indications and various RCS process variables to monitor the positions of the rods and to establish that the plant is operating within the bounds of the accident analysis assumptions (satisfying TS LCO, COLR limits and TS SR).

General Design Criterion (GDC) 13 in Title 10 of the Code of Federal Regulations Part 50, Appendix A, specifies that instrumentation shall be provided to monitor variables and systems over their operating ranges during normal operation, anticipated operation occurrences, and accident conditions. North Anna TS 3.1.7 requires operability of the Rod Position Indication and Demand Position Indication

Serial No.15-040 Docket Nos. 50-338/339 Page 11 of 13 Attachment 1 Systems, and thereby provides additional measures to ensure compliance with the control rod alignment and insertion limits. The proposed alternative monitoring maintains compliance with GDC 13.

4.2 Precedents The proposed Change is similar to changes approved for R. E. Ginna Nuclear Power Station on June 25, 2013.

4.3 Significant Hazards Consideration Dominion has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, "Issuance of amendment," as discussed below:

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

Response: No.

The proposed change provides an alternative method for verifying rod position of one rod. The proposed change meets the intent of the current specification in that it ensures verification of position of the rod once every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months . The proposed change provides only an alternative method of monitoring rod position and does not change the assumptions or results of any previously evaluated accident. Therefore, operation of the facility in accordance with the proposed amendment would not involve a significant increase in the probability or consequences of an accident previously evaluated.

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

Response: No.

The proposed change provides only an alternative method of determining the position of one rod. No new accident initiators are introduced by the proposed alternative manner of performing rod position verification. The proposed change does not affect the reactor protection system. Hence, no new failure modes are created that would cause a new or different kind of accidents from any accident previously evaluated. Therefore, operation of the facility in accordance with the proposed amendments would not create the possibility of a new or different kind of accident from any previously evaluated.

Serial No.15-040 Docket Nos. 50-338/339 Page 12 of 13 Attachment 1

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

Response: No.

The basis of TS 3.1.7 states that the operability of the rod position indicators is required to determine control rod positions and thereby ensure compliance with the control rod alignment and insertion limits. The proposed change does not alter the requirement to determine rod position but provides an alternative method for determining the position of the affected rod. As a result, the initial conditions of the accident analysis are preserved and the consequences of previously analyzed accidents are unaffected. Therefore, operation of the facility in accordance with the proposed amendment would not involve a significant reduction in a margin of safety.

Based on the above, Dominion concludes that the proposed amendment presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and, accordingly, a finding of "no significant hazards consideration" is justified.

4.4 Conclusions Dominion concludes, 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) 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.

5.0 ENVIRONMENTAL CONSIDERATION

The proposed amendment changes requirements with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The proposed amendment involves no significant increase in the amounts and no significant change in the types of any effluents that may be released offsite, and no significant increase in individual or cumulative occupational radiation exposure. Dominion's review concluded that the proposed amendment involves no significant hazards consideration and meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

Serial No.15-040 Docket Nos. 50-338/339 Page 13 of 13 Attachment 1

6.0 REFERENCES

6.1 Constellation Energy - "License Amendment Request for Alternate Rod Position Monitoring", R. E. Ginna Nuclear Power Plant, Docket No. 50-244, dated April 20, 2012 [ML12115A307]

6.2 USNRC -'Ginna Nuclear Power Plant - Re: Issuance of Amendment Approving the Use of Alternate Control and Shutdown Rod Position Monitoring System (TAC NO. ME8514),' dated June 25, 2013 [ML13081A316]

Serial No.15-040 Docket Nos. 50-338/339 Attachment 2 MARKED-UP TECHNICAL SPECIFICATIONS PAGE Virginia Electric and Power Company (Dominion)

North Anna Power Station Units I and 2

Rod Position Indication 3.1.7 3.1 REACTIVITY CONTROL SYSTEMS 3.1.7 Rod Position Indication LCO 3.1.7 The Rod Position Indication (RPI) System and the Demand Position Indication System shall be OPERABLE.

APPLICABILITY: MODES 1 and 2.

ACTIONS

- - - - - - - - - - - - NOTE -----------------

Separate Condition entry is allowed for each inoperable rod position indicator and each demand position indicator.

CONDITION REQUIRED ACTION COMPLETION TIME A. One RPI per group A.1 Verify the position Once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months inoperable for one or indirectly of the rods more groups. with inoperable position indicators by using movable incore detectors.

OR A.2 Reduce THERMAL POWER 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months Inser A to

50% RTP.

North Anna Units 1 and 2 3.1.7-1 Amendments 231ý212

Rod Position Indication 3.1.7 ACTIONS CONDITION REQUIRED ACTION L COMPLETION TIME D. One demand position D.1.1 Verify by Once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months indicator per bank administrative means inoperable for one or all RPIs for the more banks., affected banks are OPERABLE.

y AND D.1.2 Verify the most Once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months withdrawn rod and the least withdrawn rod of the affected banks are

12 steps apart.

OR D.2 Reduce THERMAL POWER 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months to 5 50% RTP.

E. Required Action and E.1 Be in MODE 3. 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months associated Completion Time not met.

SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.1.7.1 Perform CHANNEL CALIBRATION of each RPI. In accordance with the Surveillance Frequency Control Program

During North Annga Unit 2 Cyele 22, the Condition of two demfand position indicators per bank ioe lefrone r~roie banks is allowed with a Required Action to restore one deffand posituionindicator per bank aiid a Completion Timfe of 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months provided the Red Contral Systemf is immnediattly-placed in a condition incapable of autefmatie red movemenmt and verify by-I

/

-ad-minist-rative m~eana.s that the R.P-Tfor the affcctcd banks are OPERABLE a4nd the reds are aligned within 12 steps. if the 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months Completon Time is not Mai pnt i l>ndliiA4n l, North Anna Units 1 and 2 3.1.7-3 Amendments ---/25-17

Inset A Reauired Action .4-Completion Time OR

- - -- Note ---------------

Rod position monitoring by Action A.3.1 and A.3.2 may be applied to only one inoperable rod position indicator and shall be allowed until an entry into MODE 5.

A.3.1 Verify the position of the rod with the Once within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months of condition entry inoperable rod position indication (or rod control system indication of indirectly by using the movable incore potential rod movement) AND every 31 detectors. days thereafter AND A.3.2 Review the parameters of the rod Once within 16 hours1.851852e-4 days 0.00444 hours 2.645503e-5 weeks 6.088e-6 months and every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months control system for indications of rod thereafter movement for the rod with an inoperable position indicator.

Serial No.15-040 Docket Nos. 50-338/339 Attachment 3 PROPOSED TECHNICAL SPECIFICATIONS PAGES Virginia Electric and Power Company (Dominion)

North Anna Power Station Units 1 and 2

Rod Position Indication 3.1.7 3.1 REACTIVITY CONTROL SYSTEMS 3.1.7 Rod Position Indication LCO 3.1.7 The Rod Position Indication (RPI) System and the Demand Position Indication System shall be OPERABLE.

APPLICABILITY: MODES 1 and 2.

ACTIONS

-- - - - - - ------------ NOTE ------

Separate Condition entry is allowed for each inoperable rod position indicator and each demand position indicator.

CONDITION REQUIRED ACTION COMPLETION TIME A. One RPI per group A.1 Verify the position Once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months inoperable for indirectly of the rods one or more with inoperable groups. position indicators by using movable incore detectors.

OR A.2 Reduce THERMAL POWER to 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months 50% RTP.

OR NOTE------------

Rod position monitoring by Action A.3.1 and A.3.2 may be applied to only one inoperable rod position indicator and shall be allowed until an entry into MODE 5.

A.3.1 Verify the position of Once within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months the rod with the of condition entry inoperable rod position (or rod control indication indirectly system indication by using the movable of potential rod incore detectors. movement) and every 31 days thereafter.

(continued)

North Anna Units 1 and 2 3.1.7-1 Amendments

Rod Position Indication 3.1.7 ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME I AND A. (continued)

A.3.2 Review the parameters Once within of the rod control 16 hours1.851852e-4 days 0.00444 hours 2.645503e-5 weeks 6.088e-6 months and every system for indications 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter.

of rod movement for the rod with an inoperable position indicator.

B. More than one RPI B.1 Place the control rods Inmmediately per group under manual control.

inoperable.

AND B.2 Monitor and record RCS Once per 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months Tavg-AND B.3 Verify the position of Once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months the rods with inoperable position indicators indirectly by using the movable incore detectors.

AND B.4 Restore inoperable 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months position indicator to OPERABLE status such that a maximum of one RPI per group is inoperable.

North Anna Units 1 and 2 3.1.7-2 Amendments

Rod Position Indication 3.1.7 ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME C. One or more rods C.1 Verify the position 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months with inoperable indirectly of the rods position with inoperable indicators have position indicators by been moved in using movable incore excess of detectors.

24 steps in one direction since OR the last determination of C.2 Reduce THERMAL POWER to 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months the rod's < 50% RTP.

position.

D. One demand D.1.1 Verify by Once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months position administrative means indicator per all RPIs for the bank inoperable affected banks are for one or more OPERABLE.

banks. I AND D.1.2 Verify the most Once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months withdrawn rod and the least withdrawn rod of the affected banks are

< 12 steps apart.

OR D.2 Reduce THERMAL POWER to 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months

< 50% RTP.

E. Required Action E.1 Be in MODE 3. 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and associated Completion Time not met.

North Anna Units 1 and 2 3.1.7-3 Amendments

Rod Position Indication 3.1.7 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.1.7.1 Perform CHANNEL CALIBRATION of each RPI. In accordance with the Surveillance Frequency Control Program I

North Anna Units 1 and 2 3.1.7-4 Amendments

Serial No.15-040 Docket Nos. 50-338/339 Attachment 4 PROPOSED TECHNICAL SPECIFICATIONS BASES PAGES (for information only)

Virginia Electric and Power Company (Dominion)

North Anna Power Station Units I and 2

Rod Position Indication B 3.1.7 BASES LCO LCO 3.1.7 specifies that the RPI System and the Bank Demand Position Indication System be OPERABLE for each rod. For the rod position indicators to be OPERABLE requires meeting the SR of the LCO and the following:

In addition, rod position indication for a single rod a. The RPI System indicates within 12 or 24 steps of the can be determined by group step counter demand position as required by measuring the CRDM LCO 3.1.4, "Rod Group Alignment LiM ;

stationary gripper coil voltage using a b. For the RP System therc ar no f.ail.d eoik; and temporary monitoring device that provides T-*-

he Bank Demand Indication System has been calibrated alarm capability; and either in the fully inserted position or to the RPI System.

The 12 step agreement limit between the Bank Demand Position Indication System and the RPI System indicates that the Bank Demand Position Indication System is adequately calibrated, and can be used for indication of the measurement of rod bank position.

A deviation of less than the allowable limit, given in LCO 3.1.4, in position indication for a single rod, ensures high confidence that the position uncertainty of the corresponding rod group is within the assumed values used in the analysis (that specified rod group insertion limits).

These requirements ensure that rod position indication during power operation and PHYSICS TESTS is accurate, and that design assumptions are not challenged.

OPERABILITY of the position indicator channels ensures that inoperable, misaligned, or mispositioned rods can be detected. Therefore, power peaking, ejected rod worth, and SDM can be controlled within acceptable limits.

APPLICABILITY The requirements on the RPI and step counters are only applicable in MODES I and 2 (consistent with LCO 3.1.4, LCO 3.1.5, and LCO 3.1.6), because these are the only MODES in which power is generated, and the OPERABILITY and alignment of rods have the potential to affect the safety of the unit. In the shutdown MODES, the OPERABILITY of the shutdown and control banks has the potential to affect the required SDM, but this effect can be compensated for by an increase in the boron concentration of the Reactor Coolant System.

North Anna Units 1 and 2 B 3.1.7-3 Revision -)-

Rod Position Indication B 3.1.7 BASES ACTIONS The ACTIONS table is modified by a Note indicating that a separate Condition entry is allowed for each inoperable rod position indicator and each demand position indicator. This is acceptable because the Required Actions for each Condition provide appropriate compensatory actions for each inoperable position indicator.

A.1 When one RPI channel per group fails, the position of the rod may still be determined indirectly by use of the movable incore detectors. The Required Action may also be satisfied by ensuring at least once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months that F (Z) satisfies LCO 3.2.1, FN satisfies LCO 3.2.2, and SHUTDOWN MARGIN is within the limits provided in the COLR, provided the nonindicating rods have not been moved. Based on experience, normal power operation does not require excessive movement of banks. If a bank has been significantly moved, the Required Action of C.1 or C.2 below is required. Therefore, verification of RCCA position within the Completion Time of 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months is adequate for allowing continued full power operation, since the probability of simultaneously having a rod significantly out of position and an event sensitive to that rod position is small.

A.2 Reduction of THERMAL POWER to

50% RTP puts the core into a condition where rod position is not significantly affecting core peaking factors (Ref. 2).

The allowed Completion Time of 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months is reasonable, based on operating experience, for reducing power to ! 50% RTP from full power conditions without challenging unit systems and allowing for rod position determination by Required Action A.1 above.

BB.1 B.2, B.3, and B.4 When more than one RPI per group fail, additional actions are necessary to ensure that acceptable power distribution limits are maintained, minimum SDM is maintained, and the potential effects of rod misalignment on associated accident analyses are limited. Placing the Rod Control System in manual assures unplanned rod motion will not occur. Together with the indirect position determination available via movable incore detectors will minimize the potential for rod (continued)

North Anna Units 1 and 2 B 3.1.7-4 Revision-0

Insert B - TS Bases 3.1.7 Actions A Note has been added to Conditions A.3.1 and A.3.2 to ensure that the alternate monitoring requirements are not used as a long term means of verifying rod position.

The intended use of this alternate is to allow for monitoring until plant entry into a Mode 5 outage of sufficient duration and repair of the RPI can be safety performed. This ensures that at most, the alternate is used for 18 months or one operating cycle.

A.3.1 When one RPI fails, the position of the rod can still be determined by use of the movable incore detectors. Based on experience, normal power operation does not require excessive movement of banks. If a bank has been significantly moved, the Required Action of C.1 or C.2 below is required. Therefore, verification of control rod position within the Completion Time of 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months is adequate for allowing continued full power operation, since the probability of simultaneously having a rod significantly out of position and an event sensitive to that rod position is small. To provide verification of reliability of alternate monitoring, rod position will be verified by movable incore detectors every 31 days. The 31-day frequency minimizes use of the movable incore monitoring system and can be performed concurrently with existing surveillance requirements for Hot Channel Factors.

A.3.2 Review of CRDM stationary gripper coil voltage using the alternate monitoring method for indication of control rod movement for the rod with inoperable position indicator will be within 16 hours1.851852e-4 days 0.00444 hours 2.645503e-5 weeks 6.088e-6 months and then every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter. Verification of control rod position within the completion time of 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months is adequate for allowing continued full power operation, since the probability of simultaneously having a rod significantly out of position and an event sensitive to that rod position is small. Should stationary gripper coil voltage of the control rod indicate movement, a determination of the control rod positions will be made using the movable incore detectors within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months . To provide verification of reliability of alternate monitoring, rod position will be verified by movable incore detectors every 31 days. The 31-day frequency minimizes use of the movable incore monitoring system and can be performed concurrently with existing surveillance requirements for Hot Channel Factors.

v t e Letter Sequence Request
TAC:MF5683, (Approved, Closed)
Initiation Request Acceptance... Administration Questions Answers Results Approval Other:
MONTHYEAR2015-02-04 [Table View]

ML15041A667

Text

SUMMARY

3.0 TECHNICAL EVALUATION

4.0 REGULATORY EVALUATION

5.0 ENVIRONMENTAL CONSIDERATION

6.0 REFERENCES

SUMMARY

3.0 TECHNICAL EVALUATION

4.0 REGULATORY EVALUATION

5.0 ENVIRONMENTAL CONSIDERATION

6.0 REFERENCES

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