ML20217B211

Informs That During Insp of Farley Units 1 & 2 in Jan-March 1997,NRR Led Insp Team Identified Tornado Missile Protection Issue W/Exhaust Silencers for DG for Both Units

ML20217B211
Person / Time
Site:	Farley
Issue date:	04/02/1997
From:	Gallo R NRC (Affiliation Not Assigned)
To:	Berkow H NRC (Affiliation Not Assigned)
Shared Package
ML20217B144	List: ML20217B137 ML20217B181 ML20217B196 ML20217B211
References
NUDOCS 9804220449
Download: ML20217B211 (2)

Text

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NUCLEAR REGULATORY COMMISSION j

J o WASHINoTON, D.C. 20eeH001 April 2, 1997 MEMORANDUM TO: Herbert N. Berkow, Project Director Project Directorate II-2 Division of Reactor Proje -

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FROM: Robert M. Gallo, Chief Special Inspection Branch y -

g g I Division of Inspection'and Support ~ Programs

SUBJECT:

FARLEY NUCLEAR PLANT UNITS 1 AND 2 - LICENSING / DESIGN BASIS FOR TORANDO MISSILE PROTECTION During the design inspection of Farley Units 1 and 2 in January - March 1997, the NRR led inspection team identified a tornado missile protection issue with '

exhaust silencers for the diesel generators for both units. The exhaust silencers for diesel generators (including the station blackout diesel generator) for both units were installed outside, on the roof of the diesel generator buildings. The equipment appears to be protected from horizontal tornado generated missiles by building walls. However, the equipment is i susceptible to vertical and other non-horizontal missiles. The team 1 questioned the adequacy of this design. In response, the licensee stated that their licensing / design basis did not require the equipment to be protected i from vertical and other non-horizontal tornado missiles. But, the licensee '

could not provide any documentation supporting their statement.

FSAR Section 3.5.4 states that Category I equipment and piping outside containment are either housed in Category I structures or buried underground.

FSAR Table 3.2-1 addresses the tornado missile protection for the diesel generators. However, FSAR Table 3.2-1 does not address the exhaust silencers associated with the diesel generators. FSAR Section 3.3.2.1 discusses three types of missiles considered for tornado missile protection. However, their spectra were not clearly defined. The standard review plan (SRP) Section 3.5.1.4 identifies the specific missile spectra which includes horizontal and vertical velocities. Specifically, the missile spectra included vertical velocities of 70% of the postulated horizontal velocities.

The Farley safety evaluation report issued on May 2,1975, Section 3.5.5 stated that the seismic Category I structures and components are either designed for or shielded from postulated missiles, including tornado-induced missiles and missiles generated by failure of components. Other documentation reviewed, such as NRC questions / answers relative to the missile protection, did not identify or discuss any specific missile trajectories.

9804220449 980421 PDR ADOCK 05000348 P PDR

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'. H. N. Berkow ,

The installed condition of the diesel generator exhaust silencers would not conform to the GDC 2 requirements if the design / licensing basis requires consideration of tornado missile protection of this equipment for vertical and other non-horizontal missiles. Such a missile, generated by tornado, could restrict the exhaust flow path from the diesel generator and adversely affect the diesel generator operability. Since a tornado could be an initiating event for a loss of off-site power as well as a station blackout, the consequence of lack of adequate tornado missile protection to the diesel generator silencers will be severe.

Please coordinate the review of this issue by NRR staff to determine whether the tornado missile protection for Farley Units 1&2 design / licensing basis included missile spectr,a other than horizontal missiles and any generic implications. The licensee stated that not all the plants in their vintage considered the vertical and non-horizontal missiles in their design for tornado missile protection.

Please contact Roy Mathew, the team leader for the design inspection, at 415-2965 for further information.

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