ML022330373

Severe Accident Mitigation Alternatives

ML022330373
Person / Time
Site:	Catawba
Issue date:	08/08/2002
From:	Gordon Peterson Duke Power Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML022330373 (3)

Text

SDuke GARY R.PETERSON Power Vice President Catawba Nuclear Station A Duke Energy Company Duke Power CNOZ VP / 4800 Concord Rd York, SC 29745 803 831 4251 803 831 3221 fax grpeters@duke-energy.com August 8, 2002 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

SUBJECT:

Duke Energy Corporation Catawba Nuclear Station, Units 1 and 2 Docket Numbers 50-413 and 50-414 Severe Accident Mitigation Alternatives

REFERENCE:

1) Letter, USNRC to Duke Energy Corporation Dated May 14, 2002,

SUBJECT:

Request for Comments on the Draft Plant-Specific Supplement 9 to the Generic Draft Environmental Impact Statement Regarding Catawba Nuclear Station, Units 1 and 2.

Gentlemen:

Section 5.2.7 of Reference 1 identifies two Severe Accident Mitigation Alternatives (SAMAs): one to provide back-up power to the hydrogen igniters for Station Blackout (SBO) events and the other to install flood protection around the 6900/4160 volt transformers. The NRC staff states that since these SAMAs do not relate to adequately managing the effects of aging during the period of extended operation, they need not be implemented as part of license renewal pursuant to 10 CFR Part 54. The staff intends to pursue these two SAMAs as current operating license issues. Catawba has reviewed these two SAMAs and concurs with the NRC that these two SAMAs are not within the scope of license renewal and should be addressed separate from any license renewal proceedings. This letter provides the Catawba Nuclear Station position on these two SAMAs.

For the first SAMA, concerning the installation of back-up power to the hydrogen ignition system during a SBO event, Catawba agrees with the NRC staff that depending on the design requirements there may be a cost-beneficial modification that provides sufficient alternative power during a SBO to the hydrogen ignition system. The NRC staff has determined that this issue is sufficiently important for PWRs with ice-condenser containment and BWR Mark III containments that the NRC has made the issue a Generic Safety Issue (GSI), GSI-189 Susceptibility of Ice-Condenser and Mark III Containments to Early Failure from Hydrogen Combustion During a Severe Accident. As part of the resolution of GSI-189, the NRC is evaluating potential www duke-energy com A-c)D

U.S. Nuclear Regulatory Commission Page 2 August 8, 2002 improvements to hydrogen control provisions in ice-condenser plants to reduce their vulnerability to hydrogen-related containment failures during a SBO. This will include an assessment of the costs and benefits of various options. Catawba will evaluate various possible plant design and procedural changes to address this issue. However, since this issue is being pursued by the NRC as a generic issue for ice-condenser and BWR Mark III containments, Catawba will monitor the NRC resolution of GSI-189 as a current operating license issue.

For the second SAMA, concerning the installation of flood protection around the 6900/4160 volt transformers, Catawba also agrees with the NRC staff conclusion in Reference 1. Catawba is currently in the process of designing and scheduling the installation of flood protection for the 6900/4160 volt transformers for Units 1 and 2. The current schedule is to have this modification completed by March 31, 2005. Catawba will keep the NRC Staff informed on the progress of this modification and any changes to the schedule. This is the only regulatory commitment contained in this letter.

Duke Energy and Catawba have been actively involved since before 1988 in the development of plant-specific probabilistic risk assessments (PRA), individual plant examinations (IPE/IPEEE), and component/system reliability studies to evaluate severe accidents at Catawba. Risk insights from various Catawba risk assessments have been identified and implemented to improve both the design and operation of the plant.

These changes to the plant have been prioritized based on risk significance and implemented accordingly. The implementation of such improvements has reduced the risk associated with major contributors identified by the Catawba PRA and has enhanced overall plant safety.

Consideration of the two issues identified in Reference 1 continues the activities previously taken by Duke Energy to use risk insights to continuously improve the safety of Catawba Nuclear Station.

If you have any questions regarding this submittal, please contact Randall D. Hart at 803-831-3622.

Sincerely, Peterson RDH/s

U.S. Nuclear Regulatory Commission Page 3 August 8, 2002 xc:

L.A. Reyes U.S. Nuclear Regulatory Commission Regional Administrator, Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, GA 30303 D.J. Roberts Senior Resident Inspector (CNS)

U.S. Nuclear Regulatory Commission Catawba Nuclear Station C.P. Patel (Addressee Only)

NRC Senior Project Manager (CNS)

U.S. Nuclear Regulatory Commission Mail Stop 08-H12 Washington, D.C. 20555-0001 R.L. Franovich Senior Project Manager Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 12-G15 Washington, D.C. 20555-0001 J.H. Wilson Senior Project Manager Office of Nuclear Reactor Regulation Mail Stop 12-D3 U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Anne Cottingham, Esquire Winston and Strawn 1400 L Street, NW Washington, DC 20005