ML20094E014

Final Deficiency Rept,Item 91 Re Broken/Cracked Puffer Piston Rods in Brown Boveri 5HK Circuit Breakers (IE Info Notice 83-84).Item Not Reportable Under 10CFR50.55(e) as Deficiency Would Not Adversely Affect Safe Operation

ML20094E014
Person / Time
Site:	Fermi
Issue date:	07/24/1984
From:	Jens W DETROIT EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
91, EF2-69-274, IEIN-83-84, NUDOCS 8408090062
Download: ML20094E014 (2)

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' Wayne H. Jens

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v,c. pres.oen:

' Nuclear Operattons Fermi-2 64M Nmh N,e Hghway Newport. %chgan 4840

pts)ssS41so July 24, 1984 EF2-69,274 Mr. - James G. Keppler Regional Administrator Region III U.' S. Nuclear-Regulatory _ Commission; 799 Roosevelt Road Glen Ellyn, Illinois 60137

Reference:

(1) Fermi 2 NRC Docket No. 50-341 (2) Letter, D.

A.

Wells to J.

G.

Kepplerr April 19, 1983, EF2-62624 (3) IE Information Notice No. 83-84: ' Cracked and Broken Piston Rods in Brown Boveri Electric Type 5HK Breakers s

j

Subject:

Final Evaluation of 10CFR50.55(e)_ Item 91 4

" Broken / Cracked Puf fer Piston Rods in Brown Boveri 5HK Circuit Breakers" Detroit Edison has completed its investigation of Item 91 and has determined the deficiency is not reportable under 10CFR50.55(e).

This item involved cracked and broken puffer piston rods in Brown Boveri Electric (BBE) Type SHK' Breakers.

Puffer pistons in the BBE 5RK breakers perform two functions.

For low current interruptions the puffer is I

needed to assist the magnetic forces to move the arc into the interrupting chamber.

The-arc may not be extinguished.

if the puffer piston fails.

The other function performed by-the puffer piston is to provide a pneumatic cushion which

~

reduces the shock forces imposed on'the mechanism and current carrying parts upon opening.

A failure of,the..

puffer piston does not affect the breaker's ability to interrupt fault currents, but the resulting impairment of arc st aoression at low currents could cause pitting of contact surfaces.- A failure of the-puffer pi'ston.could

/

reduce the number of operations ~before maintenan_c'e on the breaker would be necessary.

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i JUL 30 894 8400090062 B40724 f

H PDR ADOCK 05000341 PDR JM~[

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r Mr. James G. Keppler July 24,-1984-EF2-69,274 Page 2 Detroit Edison has concluded that this deficiency is not reportable under 10CPR50.55(e) because although the

' deficiency may shorten the. maintenance interval, the deficiency would not-adversely affect the safe operation of the plant.

Detroit Edison, however, has followed the recommendations of IE Notice 83-84 and taken the following actions:

o All Brown Boveri 5HK breakers used in safety-related applications have been identified.

o All puffer piston shafts in breakers associated with safety-related equipment have been replaced with shafts made from a material more resistant to cracking.

o Preventive maintenance procedures have been modified to require inspection of the puffer piston shafts.

This is considered the final report on this item.

If you have any questions concerning this matter, please contact Mr. Lewis P. Bregni, (313) 586-5083.

Sincerely, cc:

Mr.

P. M. Byron bk Mr.

R.

C.

DeYoung Mr.

R.

C. Knop r

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