ML20084B092

Final Interim Rept,Item 118,re Design of Controls for Nitrogen Inerting/Purge Sys Containment Isolation Valves. Initially Reported on 840309.Design Modified to Add Electrically & Physically Separated Isolation Signals

ML20084B092
Person / Time
Site:	Fermi
Issue date:	04/16/1984
From:	Jens W DETROIT EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
118, EF2-66736, NUDOCS 8404260066
Download: ML20084B092 (2)

Text

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f= O p1 B W yne H. Jins j Vice Presdent Nuclear Operatums MI bb (a IIe I "" April 16, 1984 EF2-66736 Mr. James G. Keppler Regional Administrator Region III U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137

Reference:

Fermi 2 NRC Docket No. 50-341

Subject:

Report of 10CFR50.55(e) Item on Deficiency in Design Concerning the Nitrogen Inerting

, System Isolation Valves (#118)

On March 9, 1984, Detroit Edison's Mr. L. P. Bregni, Engineer - Licensing telephoned Mr. J. E. Konklin of the NRC Region III,' to report a deficiency in the -design of the controls for the nitrogen inerting/ purge system con-taintnent isolation valves at the Fermi 2 site.

Descriptions (LC) of Deficiency A design change package (DCP) for the nitrogen inerting/

purge system was released for construction, in accordance with Detroit Edison Procedure 3.24. The design change was implemented in the field as called for by the DCP. The

-design for the applicable primary containment isolation.

valves, as released in the DCP, did not meet single fail-ure criteria as required by the FSAR. T11s deficiency was discovered by the Design Group during final review for approval of the base configuration documents (i.e.,-P& ids Logic.and Schematic diagrars) as required.by Procedure 3.19.

-The containment isolation valves in question are solenoid actuated, pneumatic powered valves designed to go to the-safe position-(closed) on-loss of power to the solenoids or loss of air. - As a consequence there. was no need for a class lE power source as long,as appropriate safety grade

. controls were used. : liowever, the controls.were designed non-safety grade which resulted in inboard and outboard cables being located in common tray systems and~ panels.

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James G. Keppler April 16, 1984 EF2-66736 Page 2 Analysis of Safety Implications:

The valves in. question are generally normally closed except as required for containment pressure or N 2/02 con-trol, or for purging prior to containment entry. The valves are required to close upon receipt of a LOCA isolation signal. As a consequence of the deficiency, however, primary containment integrity can not be assured in the event of a LOCA with a coincident single failure.

Given-these conditions, the inboard and outboard isolation valves could remain open due to a single failure in the common mode associated circuitry to the valves.

Corrective Action The design is being modified to add qualified electrically and physically separated isolation signals for the purge and inert system primary containment isolation valves..

' Detroit Edison has reviewed all primary containment isola-

. tion-valves.in a similar category (normally closed and de-energized-to-close valves), to verify that the proper

-isolation. features'have been provided. This' review ~showed

' thattthese, designs?were proper. Accordingly, Detroit ~

Edison has ' concluded that' ~this occurrence- was lisolated and no further corrective action is required.

This is1 considered lthe' final' report:on this ' item. .Comple-:

-tion.of the design, changes:and.the-field: implementation .

- willebe'.' tracked and verified 1by th'e: Nucle'ar ~ Quality Assurance Department.' 'If you have questions ~concerning -

this matter, please contact.Mr.? Lewis P.-Bregni,z(313).

586-5083. ' '

- t m Sincerely,

?cc: Mr. P.;M. Byron

$69

... 'Mr. R.-;DeYoung..

Mr. J. .E.EKonklin ,

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