ML19305E803

Suppl to Final Deficiency Rept Re Ruskin Mfg Co Vertical Fire Dampers.Suggested Mod Found to Be Unacceptable. Alternate Design Mod Developed,Applied & Tested.New Problem, Re Closure of Small Dampers,Rectified

ML19305E803
Person / Time
Site:	Wolf Creek, Callaway
Issue date:	05/08/1980
From:	BECHTEL GROUP, INC.
To:
Shared Package
ML19305E800	List: ML19305E799 ML19305E803
References
NUDOCS 8005200455
Download: ML19305E803 (6)

Text

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O Supplement To The Final Report i

On Vertical Fire Dampers i

Supplied By Ruskin Manufacturing Company For The SNUPPS Project i

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i Bechtel Power Corporation Gaithersburg, Maryland May 8, 1980

SUPPLEMENT TO THE FINAL REPORT ON VERTICAL FIRE DAMPERS FOR THE SNUPPS PROJECT The Final Report on Vertical Fire Dampers for the SNUPPS Project was transmitted to the NRC by SLNRC 80-8 dated 2/15/80. The report indicated that the dampers would be modified by installing a No. 6 screw, a washer, a star lock washer, and a hex nut in the spring slot to prevent the spring from slipping out during closure of the da=per.

This modification was subsequently judged to be unacceptable since No. 6 screws could become loose. As such, Ruskin developed an alternate design modification consisting of a small sheet metal clamp which wraps around part of the spring bracket locking the neck of the spring bracket slot.

(See attached Ruskin Drawings 5564 and 5566). Several dampers, which have been modified in accordance with the latest design modifications, have been tested and the design modification is judged to be acceptable for all vertical fire dampers.

During the investigation and modification of the vertical fire dampers at Callaway Jobsite, another proble= associated with the closure of the small size vertical fire dampers (less than 9" high) was identified. This problem has been rectified by installing a sheet metal snap-in strip which holds the bottom blade of the small fire damper in proper orientation (see attached Ruskin drawings 5565 and 5567). Since the leading edge of the bottom blade is lower than the trailing edge, this modification assures complete and consistent closure of the small vertical fire dampers. All vertical fire dampers will be modified and operationally cycled, prior to and during installation, to confirm acceptability.

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