ML092250468
| ML092250468 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 08/06/2009 |
| From: | Baxter D Duke Energy Carolinas, Duke Energy Corp |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LAR-08-04 | |
| Download: ML092250468 (19) | |
Text
Duke nergy Eah DAVE BAXTER Vice President Oconee Nuclear Station Duke Energy ON01 VP / 7800 Rochester Highway Seneca, SC 29672
, 864-873-4460 864-873-4208 fax dabaxter@dukeenergy.com August 6, 2009 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555-0001
Subject:
Duke Energy Carolinas, LLC Oconee Nuclear Site, Units 1, 2, and 3 Docket Numbers 50-269, 50-270, and 50-287 License Amendment Request for Low Temperature Overpressure Protection System Technical Specification 3.4.12, Surveillance Requirement 3.4.12.7 License Amendment Request (LAR) No. 2008-04 In accordance with 10 CFR 50.90, Duke Energy Carolinas, LLC (Duke) proposes to amend Appendix A, Technical Specifications, for Renewed Facility Operating Licenses Nos. DPR-38, DPR-47, and DPR-55 for Oconee Nuclear Station (ONS), Units 1, 2, and 3. This LAR requests the Nuclear Regulatory Commission (NRC) to review and approve a change to the technical specification (TS) 3.4.12, Low Temperature Overpressure Protection (LTOP) System, surveillance requirement (SR) frequency, specifically TS SR 3.4.12.7. TS SR 3.4.12.7 currently requires a channel calibration to be performed every 6 months. The proposed LAR changes the TS SR frequency from 6 months to 18 months. This request also proposes corresponding changes to the TS bases.
Currently, TS SR 3.4.12.7 requires the Power Operated Relief Valve (PORV) to be calibrated every 6 months. This frequency was reduced from 18 months to 6 months by License Amendment 333, 333, and 334 dated August 25, 2003. The shorter test frequency was necessary to reflect values in the supporting calculations. Because this instrumentation is located in the reactor building and not easily accessible during power operations, delays in testing the functions frequently occur; thereby, requiring the PORV to be declared inoperable.
Recently, this instrumentation has been upgraded and is more reliable and accurate. Analysis for the new instrumentation shows minimal drift over a 30 month period. This upgrade supports extending the TS SR back to an 18 month frequency.
In accordance with Duke administrative procedures and the Quality Assurance Program Topical Report, these proposed changes have been reviewed and approved by the Plant Operations Aotr www. duke-energy.corn
Nuclear Regulatory Commission License Amendment Request No. 2008-04 August 6, 2009 Page 2 Review Committee and Nuclear Safety Review Board. Additionally, a copy of this LAR is being sent to the State of South Carolina in accordance with 10 CFR 50.91 requirements.
Duke requests that this proposed license amendment be reviewed and approved in support of the Spring, 2010 refueling outage. Duke will also update applicable sections of the Oconee UFSAR, as necessary, and submit these changes per 10 CFR 50.71(e). There are no new commitments being made as a result of this proposed change.
Inquiries on this proposed amendment request should be directed to Reene' Gambrell of the Oconee Regulatory Compliance Group at (864) 873-3364.
I declare under penalty of perjury that the foregoing is true and correct. Executed on August 6, 2009.
Sincerely, Dave Baxt r, Vice President Oconee Nuclear Site
Enclosure:
- 1. Evaluation of Proposed Change Attachments:
- 1. Technical Specifications - Mark Ups
- 2. Technical Specifications - Reprinted Pages
Nuclear Regulatory Commission License Amendment Request No. 2008-04 August 6, 2009 Page 3 bc w/enclosures and attachments:
Mr. Luis Reyes, Regional Administrator U. S. Nuclear Regulatory Commission - Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 Mr. John Stang, Project Manager Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 0-8 G9A Washington, D. C. 20555 Mr. Eric Riggs (Acting)
Senior Resident Inspector Oconee Nuclear Site Mrs. Susan E. Jenkins, Manager Infectious and Radioactive Waste Management Section Department of Health & Environmental Control 2600 Bull Street Columbia, SC 29201
ENCLOSURE 1 EVALUATION OF PROPOSED CHANGE
- Evaluation of Proposed Change License Amendment Request No. 2008-04 August 6, 2009 Page 1
Subject:
License Amendment Request for Low Temperature Overpressure Protection System Technical Specification 3.4.12, Surveillance Requirement 3.4.12.7 License Amendment Request (LAR) No. 2008-04
- 1.
SUMMARY
DESCRIPTION
- 2. DETAILED DESCRIPTION 2.1 Low Temperature Overpressure Protection 2.2 Power Operated Relief Valve Requirements 2.3 Administrative Controls Requirements 2.4 Technical Specification Change Description
.3. TECHNICAL EVALUATION
- 4. REGULATORY EVALUATION 4.1 Significant Hazards Consideration 4.2 Applicable Regulatory Requirements/Criteria 4.3 Precedent 4.4 Conclusions
- 5. ENVIRONMENTAL CONSIDERATION
- Evaluation of Proposed Change License Amendment Request No. 2008-04 August 6, 2009 Page 2 1.0
SUMMARY
DESCRIPTION This LAR requests the Nuclear Regulatory Commission (NRC) to review and approve a change to the technical specification (TS) 3.4.12, Low Temperature Overpressure Protection (LTOP) System, surveillance requirement (SR) frequency, specifically TS SR 3.4.12.7.
Currently, TS SR 3.4.12.7 requires the Power Operated Relief Valve (PORV) to be calibrated every 6 months. This frequency was reduced from 18 months to 6 months by License Amendment 333, 333, and 334 dated August 25, 2003. The shorter test frequency was necessary to reflect values in the supporting calculations. Because this instrumentation is located in the reactor building and not easily accessible during power operations, delays in testing the functions frequently occur; thereby, requiring the PORV to be declared inoperable.
Recently, this instrumentation has been upgraded and is more reliable and accurate.
Analysis for the new instrumentation shows minimal drift over a 30 month period. This upgrade supports extending the TS SR back to an 18 month frequency.
2.0 DETAILED DESCRIPTION 2.1 LTOP The LTOP System limits Reactor Coolant System (RCS) pressure at low temperatures so the integrity of the reactor coolant pressure boundary (RCPB) is not compromised by violating the pressure and temperature (P/T) requirements of 10 CFR 50, Appendix G. The reactor vessel is the limiting RCPB component for providing such protection. P/T limits, provided in TS, provide the allowable combinations for operational pressure and temperature during cooldown, shutdown, and heatup to keep from violating the 10 CFR 50, Appendix G limits.
The reactor vessel material is less ductile at reduced temperatures than at normal operating temperature. Also, as vessel neutron irradiation accumulates, the material becomes less resistant to pressure stress at low temperatures. RCS pressure must be maintained low when temperature is low and may be increased only as temperature is increased.
Operational maneuvering during cooldown, heatup, or related anticipated transients must be controlled to not violate P/T limits. Exceeding these limits could lead to brittle fracture of the reactor vessel. TS present requirements for administrative control of RCS P/T to prevent exceeding the P/T limits.
- Evaluation of Proposed Change License Amendment Request No. 2008-04 August 6, 2009 Page 3 TS 3.4.12 provides RCS overpressure protection in the applicable MODES by ensuring an adequate pressure relief capacity and a limit on coolant addition capability. The pressure relief capacity requires the PORV lift setpoint to be reduced and administrative controls implemented which assure _>10 minutes available for operator action to mitigate an LTOP event. The administrative controls include limits on pressurizer level, limits on RCS pressure when RCS temperature is
< 325°F, limits on RCS makeup flow, the number of available pressurizer heater banks, requirements for alarms and restrictions upon use of the High Pressure Nitrogen System.
The LTOP approach to protecting the vessel by limiting coolant addition capability requires controls upon RCS makeup flow, the number of available pressurizer heater banks, and requires deactivating High Pressure Injection (HPI), and isolating the core flood tanks (CFTs).
Should one or more HPI pumps inject on an HPI actuation or a Core Flood Tank (CFT) discharge to the RCS, the pressurizer level and PORV may not prevent.
overpressurizing the RCS.
The administrative controls upon pressurizer level provides a (continued) compressible vapor space or cushion (either steam or nitrogen) that can accommodate a coolant insurge and prevent a rapid pressure increase, allowing the operator time to stop the increase. The PORV, with reduced lift setting, is the overpressure protection device that acts as backup to the operator in terminating an increasing pressure event.
With HPI deactivated, the ability to provide RCS coolant addition is restricted. To balance the possible need for coolant addition, the TS does not require the makeup system to be deactivated. Due to the lower pressures associated with the LTOP MODES and the expected decay heat levels, the makeup system can provide flow with the HPI pumps providing RCS makeup through the makeup control valve.
2.2 PORV Requirements As required for LTOP, the PORV is signaled to open if the RCS pressure approaches a limit set in the LTOP actuation circuit. The LTOP actuation circuit monitors RCS pressure and determines when an overpressure condition is approached. When the monitored pressure meets or exceeds the setting, the PORV is signaled to open.
Maintaining the setpoint within the limits of the LCO ensures the limits will be met
- Evaluation of Proposed Change License Amendment Request No. 2008-04 August 6, 2009 Page 4 in any event analyzed for LTOP.
When a PORV is opened in an increasing pressure transient, the release of coolant causes the pressure increase to slow and reverse. As the PORV releases steam, the RCS pressure decreases until a reset pressure is reached and the valve is signaled to close. The pressure continues to decrease below the reset pressure as the valve closes.
2.3 Administrative Control Requirements Administrative controls are necessary to assure the operator has at least ten minutes available to mitigate the most limiting LTOP event. These administrative controls include the following:
- 2) Limits upon pressurizer level;
- 3) Limits upon makeup flow capability;
- 4) OPERABLE Alarms;
- 5) Controls upon use of the High Pressure Nitrogen System; and
- 6) Restricting the number of available pressurizer heater banks.
Limiting RCS pressure based on RCS temperature provides a minimum margin to the RCS P/T limit. Restricting RCS makeup flow capability and pressurizer level and controls on the use of high pressure nitrogen limit the pressurization rate during an LTOP event. Restricting the number of available pressurizer heater banks limits the pressurization rate during an LTOP event. Alarms ensure early operator recognition of the occurrence of an LTOP event. The combination of minimum margin to the limit, limited pressurization rate and OPERABLE alarms ensure ten minutes are available for operator action to mitigate an LTOP event.
2.4 TS Change Description TS 3.4.12, LTOP System Current TS 3.4.12 establishes the channel calibration frequency of the PORV, SR 3.4.12.7 as 6 months. The proposed TS surveillance frequency will be revised from 6 months to 18 months as a result of this change.
- Evaluation of Proposed Change License Amendment Request No. 2008-04 August 6, 2009 Page 5 TS Bases 3.4.12, LTOP System With the revision of the above, the LTOP System associated TS Bases 3.4.12, specifically SR 3.4.12.7 will be revised to reflect the change in channel calibration frequency from 6 months to 18 months.
3.0 TECHNICAL EVALUATION
This change proposes that the PORV Channel Calibration frequency be revised from 6 months to 18 months since the instrumentation has been replaced with components that are more reliable and accurate. Calculations for the new instrumentation demonstrate that the instrumentation will only drift minimally over a 30 month period.- This allows the TS SR to be extended to an 18 month frequency.
The old LTOP pressure transmitter was a Rosemount 1151GP9E22B2. The specified drift for that transmitter was 0.25% Upper Range Limit (URL) for 6 months. The old LTOP pressure transmitter was qualified for normal operating conditions only.
The original Operator Aid Computer (OAC) low range RCS total loop uncertainty determined in Duke Calculation entitled, "Uncertainty Estimation for ICCM and OAC Subcooled Margin Indication", was 18.8 PSIG. The minimum low range RCS Indicator uncertainty determined in Duke Calculation entitled, "Temperature and Pressure Indication Uncertainty Allowances for Tech Spec Heat Up, Cooldown, and Hydrostatic Test Curves",
was 13.86 PSIG. The methodology used to perform the uncertainty analysis is consistent with Methodologies for the Determination of Setpoints for Nuclear Safety Related Instrumentation, ISA- RP67.04, Part I1-1994.
The upgraded LTOP pressure transmitter is a Rosernountl 154SH9RB. The specified drift is 0.2% URL for 30 months. The upgraded LTOP pressure transmitter is environmentally qualified which will allow it to be used during normal or accident conditions.
The pressure transmitter is calibrated at 0-600 PSIG, but exposed to 2150 PSIG for extended periods of time up to 30 months. In a letter from the manufacturer dated November 16, 2007, it was stated that Rosemount did not anticipate reference accuracy to be significantly affected on the new transmitter calibrated at 0-600 PSIG, but exposed to 2150 PSIG. The transmitter's Upper Range Value of 0-600 PSIG would be exceeded, but still be well within the transmitter's URL of 3000 PSIG. In addition, other Sites operating experience with the transmitter in similar applications and Oconee's limited experience with the transmitter in the LTOP application shows it to be accurate and reliable.
- Evaluation of Proposed Change License Amendment Request No. 2008-04 August 6, 2009 Page 6 The upgraded instrument block diagram is provided below:
Control Room Bargraph Indicator Rosemount 1154 Low Range PT Rochester Rochester A
- [Current Current -
Alarm Transmitter The drift for the new transmitters is being calculated assuming the surveillance interval of 24 months + 25% grace period of 6 months equaling 30 months. For the normal operating condition, the OAC low range Reactor Coolant System (RCS) total loop uncertainty is 15.7 PSIG for the upgraded LTOP instruments over a 30 month interval. For the normal operating condition, the low range RCS indicator reading total loop uncertainty is 13.2 PSIG for the upgraded LTOP instruments over a 30 month interval. The new total OAC and indicator loop uncertainties over 30 months are shown to be more conservative than those values used in the original analysis.
Since these uncertainties are less than the original uncertainties, they will have no effect on the existing uncertainty allowance used to develop the subcooled margin monitor curve or the Tech Spec Heat Up, Cooldown, and Hydrostatic Test Curves. These curves do not require revision.
While the LTOP application for this transmitter is new at Oconee, these transmitters have' been used in other nuclear applications and have been found to perform acceptably within manufacturer specifications. They are environmentally qualified for the application environment. Therefore, Duke believes that the new transmitter exceeds the capability of the original transmitter and will work acceptably in this application. Normal maintenance practices monitor instrument drift and recalibrate the instrumentation appropriately as needed. If excessive drift is seen, the instrumentation is evaluated and repaired/replaced, as appropriate. Based on that, the instrumentation is deemed appropriate and acceptable for this application and the SR can be extended back to 18 months.
- Evaluation of Proposed Change License Amendment Request No. 2008-04 August 6, 2009 Page 7
4.0 REGULATORY EVALUATION
4.1 Significant Hazards Consideration Duke Energy Carolinas, LLC, 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 amendment involve a significant increase in the probability or consequences of an accident previously evaluated.
No. This is a revision to the Technical Specification (TS) Surveillance Requirement (SR) for performing the channel calibration for the power operated relief valve (PORV).
As such, the TS SR interval extension continues to ensure the calibration is performed in a time frame supported by current analysis. The instrumentation loop has been upgraded to an environmentally qualified instrumentation loop with improved instrument uncertainty and reliability. The accidents previously evaluated have not changed.
Therefore, extending the TS SR frequency from 6 months to 18 months does not significantly increase the probability or consequences of any accident previously evaluated.
- 2) Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?
No. This revision does not impact the LTOP evaluation analysis. The method for testing remains the same. The proposed SR frequency is supported by an environmentally qualified instrumentation loop with improved instrument uncertainty and reliability.
Therefore, extending the TS SR frequency from 6 months to 18 months will not create the possibility of a new or different kind of accident from any kind of accident previously evaluated.
- Evaluation of Proposed Change License Amendment Request No. 2008-04 August 6, 2009 Page 8
- 3) Does the proposed amendment involve a significant reduction in a margin of safety?
No. The proposed change does not adversely affect any plant safety limits, setpoints, or design parameters. The change also does not adversely affect the fuel, fuel cladding, Reactor Coolant System, or Containment Operability.
Therefore, extending the TS SR frequency from 6 months to 18 months does not involve a significant reduction in a margin of safety.
4.2 Applicable Regulatory Requirements/Criteria 10 CFR 50 Appendix G GL 88-11 UJFSAR 5.2.3.7 10CFR 50.36 - LTOP satisfies Criterion 2 and 3 of 10CFR50.36.
4.3 Oconee Precedent April 10, 2003 License Amendment Request for Low Temperature Overpressure Protection System 3.4.12, Surveillance Requirements 3.4.12.5 and 3.4.12.7, Technical Specification Change Number 2002-09.
July 1, 2003 Additional Information Concerning License Amendment Request for Low Temperature Overpressure Protection System 3.4.12, Surveillance Requirements 3.4.12.5, Technical Specification Change Number 2002-09.
August 25, 2003 Leonard Olshan to Ronald Jones, Oconee Nuclear Station, Units 1, 2, And 3 RE: Issuance of Amendments 333, 333, and 334.
4.4 Conclusions In conclusion, based on the considerations discussed above, (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 adverse to the common defense and security or to the health and safety of the public.
- Evaluation of Proposed Change License Amendment Request No. 2008-04 August 6, 2009 Page 9
5.0 ENVIRONMENTAL CONSIDERATION
Duke Energy Carolinas, LLC, has evaluated this license amendment request against the criteria for identification of licensing and regulatory actions requiring environmental assessment in accordance with 10 CFR 51.21. Duke has determined that this license amendment request meets the criteria for a categorical exclusion set forth in 10 CFR 51.22(c)(9). This determination is based on the fact that this change is being proposed as an amendment to a license issued pursuant to 10 CFR 50 that changes a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or that changes an inspection or a surveillance requirement, and the amendment meets the following specific criteria.
(i) The amendment involves no significant hazards consideration.
As demonstrated in Section 4.1, revising the LTOP calibration frequency from 6 months'to 18 months does not involve significant hazards consideration.
(ii) There is no significant change in the types or significant increase in the amounts of any effluent that may be released offsite.
Revising the LTOP calibration frequency from 6 months to 18 months will not impact effluents released offsite. Therefore, there will be no significant change in the types or significant increase in the amounts of any effluents released offsite.
(iii) There is no significant increase in individual or cumulative occupational radiation exposure.
Revising the LTOP calibration frequency from 6 months to 18 months will not have an adverse impact on occupational radiation exposure. Therefore, there will be no significant increase in individual or cumulative occupational radiation exposure resulting from this.
ATTACHMENT 1 TECHNICAL SPECIFICATIONS AND TECHNICAL SPECIFICATIONS BASES MARK UPS
LTOP System 3.4.12 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY 4
SR 3.4.12.6 Verify Administrative Controls, other than 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> limits for pressurizer level, that assure _>10 minutes are available for operator action to mitigate an LTOP event are implemented for the following:
- b. Makeup flow rate;
- c. Alarms;
- d. High pressure Nitrogen System; and
- e. Verify pressurizer heater bank 3 or 4 is deactivated SR 3.4.12.7 Perform CHANNEL CALIBRATION for POF OCONEE UNITS 1, 2, & 3 3.4.12-5 Amendment Nos. ,- &-ý4
LTOP System B 3.4.12 BASES SURVEILLANCE SR 3.4.12.6 (continued)
REQUIREMENTS The Frequency is shown by operating practice sufficient to regularly assess indications of potential degradation and verify operation within the safety analysis.
/1- permance of a CHANNEL CALIBRATION is required every
- 8mds. The CHANNEL CALIBRATION for the LTOP setpoint ensure/that the PORV will be actuated at the appropriate RCS pressure the accuracy of the instrument string.
, - ying REFERENCES 1. 10 CFR 50, Appendix G.
- 3. UFSAR, 5.2.3.7.
- 4. 10 CFR 50.36.
OCONEE UNITS 1, 2, & 3 B 3.4.12-12 Amendment Nos.
ATTACHMENT 2 TECHNICAL SPECIFICATIONS AND TECHNICAL SPECIFICATIONS BASES REPRINTED PAGES
LTOP System 3.4.12 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY 4.
SR 3.4.12.6 Verify Administrative Controls, other than 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> limits for pressurizer level, that assure > 10 minutes are available for operator action to mitigate an LTOP event are implemented for the following:
- b. Makeup flow rate;
- c. Alarms;
- d. High pressure Nitrogen System; and
- e. Verify pressurizer heater bank 3 or 4 is deactivated SR 3.4.12.7 Perform CHANNEL CALIBRATION for PORV. 18 months OCONEE UNITS 1, 2, & 3 3.4.12-5 Amendment Nos. , &
LTOP System B 3.4.12 BASES SURVEILLANCE SR 3.4.12.6 (continued)
REQUIREMENTS The Frequency is shown by operating practice sufficient to regularly assess indications of potential degradation and verify operation within the safety analysis.
SR 3.4.12.7 The performance of a CHANNEL CALIBRATION is required every 18 months. The CHANNEL CALIBRATION for the LTOP setpoint ensures that the PORV will be actuated at the appropriate RCS pressure by verifying the accuracy of the instrument string.
REFERENCES 1. 10 CFR 50, Appendix G.
- 3. UFSAR, 5.2.3.7.
- 4. 10 CFR 50.36.
OCONEE UNITS 1,2, & 3 B 3.4.12-12 Amendment Nos.