NOC-AE-13003042, Submittal of Report Summary 10CFR50.59 Evaluations of Changes, Tests, and Experiments Conducted

Submittal of Report Summary 10CFR50.59 Evaluations of Changes, Tests, and Experiments Conducted

ML13304A497
Person / Time
Site:	South Texas
Issue date:	10/10/2013
From:	Marc-Anthony Murray South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-13003042
Download: ML13304A497 (5)

Text

Nuclear Operating Company South Tekas Pro/ectElectric GeneratinS Station P.. Box 289 Wd4sworth T7&

ws77483 O t b r1 ,2 3 October 10, 2013 NOC-AE-13003042 1CFR50.59 STI: 33766687 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 South Texas Project Units 1 & 2 Docket Nos. STN 50-498, STN 50-499 10CFR50.59 Summary Report Pursuant to the requirements of 10CFR50.59, the attached report contains a brief description and summary of the 10CFR50.59 evaluations of changes, tests, and experiments conducted at the South Texas Project.

There are no commitments in this letter.

If there are any questions regarding this summary report, please contact Jim Morris at (361) 972-8652 or me at (361) 972-8164.

Michael P. Murray Manager, Regulatory Affairs mk

Attachment:

10CFR50.59 Evaluation Summaries July 2011- October 2013

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NOC-AE-13003042 Page 2 of 2 cc:

(paper copy) (electronic copy)

Regional Administrator, Region IV A. H. Gutterman, Esquire U. S. Nuclear Regulatory Commission Morgan, Lewis & Bockius LLP 1600 East Lamar Boulevard Arlington, TX 76011-4511 Balwant K. Singal U. S. Nuclear Regulatory Commission Balwant K. Singal John Ragan Senior Project Manager Chris O'Hara U.S. Nuclear Regulatory Commission Jim von Suskil One White Flint North (MS 8B1) NRG South Texas LP 11555 Rockville Pike Rockville, MD 20852 Kevin Polio NRC Resident Inspector Richard Pena U. S. Nuclear Regulatory Commission City Public Service P. 0. Box 289, Mail Code: MN116 Wadsworth, TX 77483 Jim Collins Peter Nemeth City of Austin Crain Caton & James, P.C.

Electric Utility Department 721 Barton Springs Road Jamie Paul Austin, TX 78704 STP Corporate Attorney C. Mele City of Austin Richard A. Ratliff Texas Department of State Health Services Robert Free Texas Department of State Health Services

NOC-AE-13003042 Attachment Page 1 of 3 10CFR60.59 Evaluation Summaries July 2011 - October 2013 Summaries of the following 10CFR50.59 Evaluations are provided in this attachment:

No. Condition Report Subject Number

1. 04-11502-303 Replaced Engineered Safety Feature Train B Transformers with new Load Tap Changing Transformers and Voltage Regulating Controllers

2. 11-12726-8 Change to Core Operating Limits Report Figure 1 and Updated Final Safety Analysis Report Table 4.4-1

3. 09-15306-5 Leak Before Break Analysis on Pressurizer Surge Line

4. 13-3393-6 Insufficiently Annealed Strip Material in Westinghouse ZIRLO Grid

NOC-AE-1 3003042 Attachment Page 2 of 3 10CFR50.59 Evaluation Summaries July 2011 - October 2013 04-11502-303 Replaced Engineered Safety Feature Train B Transformers with new Load Tap Changing Transformers and Voltage Regulating Controllers

Description:

The subject of this evaluation is for the replacement of Engineered Safety Feature (ESF) transformers E1 B and E2B from a type with no load tap changer with similar transformers that include an automatic load tap changer.

Summary: The purpose of the Load Tap Changer (LTC) is to maintain the ESF transformer secondary side voltage within an operating band that has been analyzed as primary side voltage fluctuates. The LTC allows switchyard voltages to go down to a lower voltage without tripping the offsite power source via the degraded grid relays. The automatic primary and backup controllers are set to ensure that voltage on the safety buses will remain within design limits. An analysis was performed to ensure the degraded grid under voltage relays would not time out based on new expected minimum switchyard voltages. A failure modes and effects analysis showed that failure modes introduced by the digital primary and backup LTC changer are bounded by the failure modes of the currently installed Unit Auxiliary Transformer with analog controllers. Operator action is not required to ensure safety related equipment will still be able to perform its safety related function in the event the control room alarm indicating a failure of the primary load tap changer is received.

The evaluation shows that proposed change does not require prior NRC approval to implement.

2. 11-12726-8 Change to Core Operating Limits Report Figure I and Updated Final Safety Analysis Report (UFSAR) Table 4.4-1

Description:

The subject of this evaluation is for the revision to the Core Operating Limits Report ( COLR) Figure 1 for Unit 2 Cycle 16 (during 2RE15) and Unit 1 Cycle 18 (during 1 RE1 7) by changing the inflection point on the 2450 psia curve from 98%

power at 637.98°F to 96% power at 638.57 0 F. The proposed change also revises the minimum Departure from Nucleate Boiling Ratio (DNBR) at nominal conditions from 2.55 to 2.53 for a typical flow channel and 2.47 to 2.45 for a thimble flow channel on UFSAR Table 4.1-1.

Summary: The change is being made based on revised analysis that corrected two errors in the safety analysis.

Using the same methodology as the previous analysis, the revised analysis shows that no safety analysis acceptance limits are violated, and therefore prior NRC approval is not required.

NOC-AE-1 3003042 Attachment Page 3 of 3

3. 09-15306-5 Leak Before Break Analysis on Pressurizer Surge Line

Description:

South Texas Project applied a structural weld overlay (SWOL) to the Unit I and 2 pressurizer surge line (PSL) at the Alloy 82/182 weld location to mitigate primary to secondary water stress corrosion cracking (PWSCC).

Summary: In accordance with Regulatory Issues Summary 2010-07, STP has reviewed the application of SWOL on the Leak Before Break (LBB) qualified surge line, with the purpose of determining whether NRC approval of the revised calculation is required. The LBB evaluation for the SWOL on the PSL uses an NRC approved methodology that is based on sound engineering practice and is within the limitations of the applicable Safety Evaluation Report. The use of a methodology revision that is documented as providing results that are essentially the same as, or more conservative than, either the previous revision of the same methodology or another methodology previously accepted by NRC through issuance of an SER is not considered a departure from a method of evaluation described in the Updated Final Safety Analysis Report, therefore, NRC approval is not required.

4. 13-3393-6 Insufficiently Annealed Strip Material in Westinghouse ZIRLO Grids

Description:

The purpose of this evaluation is to evaluate the use of under annealed ZIRLO fuel mixing grid strap material in the current and future fuel core designs. The mixing grids of the center fuel assemblies of the current core for Units 1 and 2 potentially contain this under annealed material. The change permits the use of the assemblies containing this material in the current core and their limited use in future fuel cycles, as described in the Fuel Condition Evaluation.

Summary: The technical evaluation of fuel assembly grids containing insufficiently annealed grid strap material identified nine design criteria that may be adversely impacted by the condition. These criteria were evaluated and the change was shown to have minimal or no impact as shown below.

1. Grid to Rod Fretting -minimal effect

2. Mixing Vane Geometry - no impact

3. Cell Force and Clad Scratching - no impact

4. Interfaces and Clearances - no impact

5. Spacer Grid Strength - no impact

6. Rod Buckling- no impact

7. Rod Bow- no impact

8. Spent Fuel Impacts- no impact

9. Dry Cask Storage Impacts- no impact The evaluation of this condition shows that prior NRC approval is not required.