ML072960311
| ML072960311 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 10/22/2007 |
| From: | O'Grady B Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TVA-BFN-TS-418, TVA-BFN-TS-431 | |
| Download: ML072960311 (11) | |
Text
October 22, 2007
TVA-BFN-TS-418 TVA-BFN-TS-431 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Stop OWFN, P1-35 Washington, D. C. 20555-0001 Gentlemen:
In the Matter of ) Docket Nos. 50-259 Tennessee Valley Authority ) 50-260 ) 50-296 BROWNS FERRY NUCLEAR PLANT (BFN) - UNITS 1, 2, AND 3 -
TECHNICAL SPECIFICATIONS (TS) CHANGES TS-431 AND TS-418 -
EXTENDED POWER UPRATE (EPU) - EPU LARGE TRANSIENT TESTING (LTT) By letters dated June 28, 2004 (ADAMS Accession No.
ML041840109) and June 25, 2004 (ML041840301), TVA submitted license amendment applications for EPU operation at 3952 megawatts thermal (MWt) for BFN Unit 1, and BFN Units 2 and 3, respectively. On September 22, 2006, TVA submitted a supplemental TS-431 change request (ML062680459), which revised the original June 28, 2004, Unit 1 EPU application to request approval of a 5% increase in thermal power to
3458 MWt until such time as additional steam dryer analyses could be completed. The Unit 1 supplemental TS-431 request was approved by NRC on March 6, 2007 (ML063350404). Hence, all three BFN units are currently licensed for operation at 3458 MWt and approval of the subject EPU amendments would increase the maximum authorized power level for Units 1, 2, and 3 by approximately 14% to 3952 MWt.
U. S. Nuclear Regulatory Commission Page 2 October 22, 2007 In support of the subject EPU license amendment requests, this letter describes TVA's position and plans for conducting LTTs for the EPU phase of operation. In summary, TVA will perform a turbine generator load reject
transient test from EPU conditions within 60 days of operating at EPU power on Unit 1. EPU load reject tests are not being planned on Units 2 and 3. The performance of a Unit 1 load reject LTT from EPU conditions is considered a regulatory commitment as documented in Enclosure 2. A Main Steam Isolation Valve (MSIV) closure LTT from full (current rated power) was performed on June 23, 2007, and further MSIV LTTs are not considered beneficial as discussed in Enclosure 1. Enclosure 1 also provides
references to previous TVA submittals justifying not performing a full set of LTTs at EPU conditions. This proposal is consistent with those approved by NRC for other Boiling Water Reactor EPU applications.
Unit 1 is the lead BFN EPU plant since nearly all necessary hardware modifications for EPU operation are installed and
the Unit 1 reactor core is an EPU core. TVA is considering a Unit 1 mid-cycle outage in May 2008 following the Spring 2008 Unit 3 outage and prior to the peak summer load season to implement remaining modifications such as setpoint changes and any additional modifications related to steam dryers needed for EPU operation. For this to be considered feasible, TVA would need NRC review of BFN steam dryer submittals on a schedule that would allow NRC review and approval of the EPU amendments no later than April 2008.
EPU modifications are being implemented in a staged manner on Units 2 and 3. Many of the EPU modifications were completed during the Spring 2007 Unit 2 refueling outage and the Unit 2 reactor core is likewise an EPU rated core.
Unit 3 will also implement most of the EPU modifications in the upcoming Spring 2008 refueling outage.
U. S. Nuclear Regulatory Commission Page 3 October 22, 2007 TVA has determined that the additional information provided by this letter does not affect the no significant hazards considerations associated with the proposed amendments and that the proposed TS changes still qualify for the
categorical exclusion from environmental review pursuant to the provisions of 10 CFR 51.22(c)(9). Additionally, in accordance with 10 CFR 50.91(b)(1), TVA is sending a copy of this letter and enclosures to the Alabama State Department of Public Health.
If you have any questions regarding this letter, please contact me at (256) 729-3675.
I declare under penalty of perjury that the foregoing is true and correct. Executed on this 22nd day of October, 2007.
Sincerely, Original signed by:
Brian O'Grady
Enclosures:
- 2. List of Regulatory Commitments U. S. Nuclear Regulatory Commission Page 4 October 22, 2007 Enclosures cc (Enclosures):
State Health Officer
Alabama State Department of Public Health RSA Tower - Administration Suite 1552 P. O. Box 303017 Montgomery, Alabama 36130-3017 NRC Senior Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road
Athens, AL 35611-6970 Mr. Stephen C. O'Conner, Interim Branch Chief U. S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW, Suite 23T85
Atlanta, Georgia 30303-8931 Ms. Eva Brown, Project Manager U.S. Nuclear Regulatory Commission (MS 08G9)
One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739 U. S. Nuclear Regulatory Commission Page 5 October 22, 2007 JEE:BCM:BAB Enclosures cc (Enclosures): R. H. Bryan, Jr., LP 4J-C W. R. Campbell, Jr. LP 6A-C J. C. Fornicola, LP 6A-C R. G. Jones, POB 2C-BFN G. V. Little, NAB 1D-BFN R. F. Marks, Jr., PAB 1C-BFN D. C. Matherly, BFT 2A-BFN S. A. Vance, WT 6A-K E. J. Vigluicci, ET 11A-K B. A. Wetzel, BR 4X-C
NSRB Support, LP 5M-C EDMS WT CA-K, s:licensing/lic/submit/subs/Extended Power Uprate/TS-418_431-EPU Oct 2007.doc E1-1 ENCLOSURE 1 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)
UNITS 1, 2 AND 3 TECHNICAL SPECIFICATIONS (TS) CHANGES TS-431 AND TS-418 EXTENDED POWER UPRATE (EPU)
EPU LARGE TRANSIENT TESTING (LTT)
Background
By letters dated June 28, 2004 (ADAMS Accession No. ML041840109)
and June 25, 2004 (ML041840301), TVA submitted license amendment applications for EPU operation at 3952 megawatts thermal (MWt) for BFN Unit 1, and BFN Units 2 and 3, respectively. On September 22, 2006, TVA submitted a supplemental TS-431 change request (ML062680459), which revised the original June 28, 2004, Unit 1 EPU application to request approval of a 5% increase in thermal power to 3458 MWt until such time as additional steam
dryer analyses could be completed. The Unit 1 supplemental TS change also involved changes in plant operating parameters and reactor pressure-related setpoints to support a 30 pound per square inch increase in operating reactor pressure. This Unit 1 TS request was approved by NRC on March 6, 2007 (ML063350404).
Therefore, at present all three BFN units are licensed for operation at 3458 MWt at the same reactor operating pressure.
The approval of the remainder of the Unit 1 TS-431 EPU amendment and the Units 2 and 3 TS-418 EPU amendments would result in the
same power increase of approximately 14% of maximum authorized power level to 3952 MWt for the three units.
The overall EPU testing program for the BFN units is based on the guidance in Standard Review Plan (SRP) 14.2.1, Generic Guidelines for Extended Power Uprate Testing Programs, of NUREG-0800. The BFN EPU test program was described in detail in
previous EPU submittals, particularly in those dated April 25, 2005 and March 7, 2006, for TS-418 and TS-431 (ML051170244, ML051170242, ML060720248, and ML060680583).
In the April 25, 2005, submittals referenced above, with regard to planned LTTs for BFN EPU, TVA documented a basis for not performing a main generator load reject transient test and a Main Steam Isolation Valve (MSIV) closure transient test at EPU E1-2 conditions. This justification was based on SRP 14.2.1 guidelines and included elements such as an evaluation of the initial startup testing program, conduct of other required testing such as TS surveillance testing and EPU post-modification tests, similarity of the EPU design among the three BFN units, conformance with limitations associated with analytic methods, non-introduction of new thermal hydraulic-phenomena, and previous operating experience on Units 2 and 3. In support
of the TVA's stated proposal to limit the performance of multiple LTTs at EPU conditions, this enclosure provides supporting information from the testing experience gained during the recent restart of BFN Unit 1 and also references more recent operating experience on Units 2 and 3.
LTT Performed for Unit 1 Restart NRC's approval of the TS-431 supplemental change for Unit 1 operation at 3458 MWt included a License Condition 2.G(2) requiring the performance of a turbine generator load reject and a MSIV closure transient test from full power as described in NRC's letter to TVA dated September 27, 2006 (ML062360160).
NRC's basis for addition of the testing License Condition was related to NRC concerns regarding the extended shutdown of Unit 1 (since 1985), the implementation of multiple system
upgrades and plant modifications, and an increase in both reactor power and operating pressure. In a subsequent letter to TVA dated October 13, 2006 (ML062710556), NRC indicated that depending on the Unit 1 LTT results at 105% power, TVA could offer further justification to not perform additional Unit 1 LTTs at EPU conditions.
Unit 1 MSIV Closure Large Transient Test
An MSIV closure transient test from nominal full power (3458 MWt) was performed on June 23, 2007. The MSIV closure test from rated power potentially constitutes a challenging transient event since all four main steam lines are simultaneously isolated from the main condenser during the test. The integrated plant response to the scram was as expected and scram recovery was uncomplicated. All established test criteria for
the transient test were met and Unit 1 returned to power operation on June 26, 2007.
In addition, GE performed an ODYN simulation of the MSIV closure transient using similar initial reactor conditions and parameters as those that existed on BFN Unit 1 when the June 23, 2007, transient test was performed. This simulation showed that actual plant performance during the MSIV closure transient test E1-3 was reasonably bound by the ODYN analysis and was milder than predicted by the ODYN simulation. TVA provided the results of the ODYN simulation and a summary of the actual plant performance during the LTT to NRC in a submittal dated July 26, 2007 (ML072070667).
Unit 1 Generator Load Rejection Test
On June 9, 2007, Unit 1 was operating at approximately 80% rated power when an unplanned turbine trip and scram occurred.
Turbine trips and load rejects are quite similar pressurization transients. Typically, load rejects are analytically slightly more severe than turbine trips from the same power level because the turbine control valves close from an intermediate position rather than from full open as do the turbine stop valves. The post-trip analysis of the turbine trip showed the integrated plant response of the reactor shutdown systems and reactor
level/pressure control systems was as expected and the scram recovery actions following the turbine trip were uncomplicated.
Based on the good integrated systems response to the June 9 turbine trip from 80% power and to the 100% power June 23, 2007, MSIV LTT, as augmented by the good plant response observed during a full set of feedwater and condensate pump trip tests
from full power, TVA subsequently requested NRC's approval to not perform a turbine generator load reject transient test from 100% power on Unit 1. This request was submitted via TS change 461S1 dated July 3, 2007 (ML071870024) and was approved by NRC on August 14, 2007 (ML072250619).
Supplemental Operating Experience Justification for Not Performing Generator Load Reject and MSIV Closure LTTs The April 25, 2005 and March 7, 2006, EPU submittals referenced previously described the EPU testing program, which complies with the guidance in SRP 14.2.1 of NUREG-0800. Below is additional more recent operating experience not included in the April 25, 2005, TVA submittals, which further augments the experience-based justification. Also, Unit 1 successfully completed its restart testing program in August 2007 and is now
in commercial operation.
The basis for excepting the conduct of the subject LTTs in part was based on previous plant operating experience. A listing of the BFN turbine trip/load rejects and other industry experience was provided in the April 25, 2005, submittals. Units 2 and 3 have both operated for several years each at 3458 MWt and both units have experienced several turbine trip/load rejects from E1-4 full power. Additional more recent examples of BFN turbine trip/load rejects from full power are an October 12, 2007, Unit 1 turbine trip from full power - Licensee Event Report (LER) in progress, a January 11, 2007, Unit 2 load reject, which was reported in LER 260/2007-001 (ML070640280), and an October 31, 2005, Unit 3 turbine trip - LER 296/2005-003 (ML053560330).
Also, during the Unit 1 restart, as discussed above, there was a turbine trip from 80% power on June 9, 2007 - LER 259/2007-05 (ML072220430).
It is clear that BFN has a considerable operating experience base for turbine trip/load rejects events. And as discussed in the April 25, 2005 submittals, the performance of additional load reject LLTs at EPU conditions would provide no significant benefits especially on Units 2 and 3. However, since there is limited operating experience on Unit 1 regarding turbine trip/load rejects from near full power, a commitment to perform
the LTT at EPU is provided in Enclosure 2.
The experience base on MSIV closure events is smaller since due to improvements in surveillance testing methods and related setpoint changes implemented in the industry, MSIV closure trips at BWRs have become rare. Accordingly, the June 23, 2007, BFN Unit 1 MSIV closure LTT is provides the best example of
applicable operating experience.
The June 23, 2007, Unit 1 MSIV closure LTT was performed from the current licensed full power of 3458 Mwt. The integrated plant response during full power MSIV transient test was uncomplicated and plant systems response was well-behaved. The transient event was mild with peak reactor pressure during the MSIV closure rising approximately 40 psi. In addition, GE performed an ODYN MSIV closure transient simulation using
similar initial reactor conditions and operating parameters as those that existed on BFN Unit 1 when the June 23, 2007, transient test was performed. This simulation showed that actual plant performance during the June 23, 2007, MSIV closure transient test was bound by the ODYN analysis and was milder than predicted by the ODYN simulation. This simulation provides additional assurance that the computer modeling and analytical
methods are reasonable and conservative. TVA provided the results of the ODYN simulation of the MSIV transient to NRC in a July 26, 2007, submittal and computer plots showing actual reactor narrow and wide range water level, average neutron power, and reactor pressure during the MSIV transient was provided to NRC in the previously referenced July 3, 2007, TS change 461S1 submittal.
E1-5 Since the current Unit 1 design configuration includes the EPU modifications which would influence plant response to MSIV closure events, the operating experience from the Unit 1 MSIV LTT applies directly to the base EPU design for all 3 units.
The plant response to the Unit 1 105% power MSIV LTT demonstrated the soundness of the EPU design modifications and provides confidence that the Units 1, 2, and 3 response at EPU
conditions would likewise be acceptable. Therefore, performance of additional MSIV LTTs at EPU conditions would provide no significant benefits. Accordingly, TVA does not plan to perform additional MSIV closure events at EPU conditions.
ENCLOSURE 2 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)
UNITS 1, 2 AND 3 TECHNICAL SPECIFICATIONS (TS) CHANGES TS-431 AND TS-418 EXTENDED POWER UPRATE (EPU)
LIST OF REGULATORY COMMITMENTS