ML101121085
| ML101121085 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 04/20/2010 |
| From: | Krich R Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML101121085 (3) | |
Text
Tennessee Valley Authority 1101 Market Street, LP 3R Chattanooga, Tennessee 37402-2801 R. M. Krich Vice President Nuclear Licensing April 20, 2010 10 CFR 50.4 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 1 Facility Operating License No. NPF-90 NRC Docket No. 50-390
Subject:
Commitment Summary Report The purpose of this letter is to provide the Watts Bar Nuclear Plant Commitment Summary Report for the period of June 17, 2008 through December 4, 2009, as required by Nuclear Energy Institute's "Guidelines for Managing NRC Commitment Changes." This report summarizes docketed commitments that Tennessee Valley Authority has evaluated and revised using administrative controls that incorporate the guidelines.
There are no regulatory commitments in this letter. Please direct any questions concerning this matter to Kevin Casey, Senior Project Manager at (423) 751-8523.
Respectfully, R. M. Krich
Enclosure:
Commitment Summary Report cc (Enclosure):
NRC Regional Administrator - Region II NRC Senior Resident Inspector - Watts Bar Nuclear Plant printed on recycled paper k-f
Enclosure Commitment Summary Report Commitment Evaluation No./
Source Summary of Original Summaryiof Basis/Justification For Commitment Document Commitment Changes Changes Tracking No.
NC0920006006 Tennessee Valley Authority's (TVA's)
Letter to NRC Dated June 30, 1994 "Severe Accident Mitigation Design Alternatives (SAMDAs)
Evaluation from Updated Individual Plant Evaluation (IPE)"
TVA will develop a plant procedure which would facilitate the cross-tie of the 500kV offsite power to the 6.9kV shutdown boards. This procedure would provide an additional, diverse source of offsite power in the event of loss of the normal 161kV offiste power supply to the shutdown boards. This enhancement addresses the second largest contributor to core damage risk - station blackout.
Decommit A design change was implemented to convert the Watts Bar Nuclear Plant (WBN) 500kV switchyard to a double breaker bus configuration. This modification included the WBN, Unit 2 Power System Optimization Project (PSOP) metering which is required for compliance with North American Electric Reliability Corporation transient stability standards. These changes remove the capability to backfeed to the Unit 1 shutdown boards. The intent of the PSOP is to reduce plant generation risk, therefore increasing plant generation stability.
In addition to these modifications, other WBN, Unit 1 modifications have reduced the risk of certain design basis events that involve the loss of AC power. Additionally, in preparation for licensing WBN, Unit 2, the SAMDA analysis and Probabilistic Risk Assessment for WBN have been updated and no longer take credit for the 500 kV cross-tie.
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Enclosure Commitment Summary Report Commitment Summary of Evaluation No./
Source Summary of Original Summaryeof Basis/Justification For Commitment Document Commitment Commitment Changes Tracking No.
Changes NC0930238006 TVA's Letter to In cases where design or procurement is Commitment Scope Engineering Specification N3M-940, NRC Dated not complete as of the date of this report, Clarified - Refer to "Design and Procurement of Lifting July 28, 1993 WBN is committed to be in compliance Basis/Justification Devices," defines "Special Lifting "Generic Letter 81-prior to the first time the specific lifting For Devices" to include all forms of rigging 07 - NUREG-0612 device is used after fuel load per Site Changes when designed and dedicated to
- Control of Heavy Standard Practice (SSP) 6.06.
handle a specific critical load or loads.
Loads at Nuclear This imposes ANSI N14.6 testing Power Plants -
The commitment evaluation only affected requirements on ASME B30.9 devices, Revised the portion of commitment and is not the intent of the Response" NC0930238006 that requires WBN to requirements of NUREG-0612 or load test and inspect slings (ASME B30.9 Generic Technical Activity A-36 which devices) to ANSI N14.6 requirements with address slings and special lifting a periodicity of 10 years.
devices separately.
ASME B30.9 devices, slings, are proof tested to 200% rated capacity by the manufacturer and are inspected by a qualified rigger prior to use, ensuring that the slings are capable of performing their function with sufficient factors of safety. Additionally, slings are regulated by OSHA Regulation 1910.184(c)(4) wherein it is specified that slings shall not be loaded in excess of their rated capacity.
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