ML20086C861

Followup Part 21 Rept Re Failure to Update Room Pressurization Calculations to Reflect Final Design Vent Paths.Reactor Bldg,Room R206C Cannot Withstand Calculated Pressurization Following Postulated High Energy Line Break

ML20086C861
Person / Time
Site:	Columbia
Issue date:	11/18/1983
From:	Conn W BURNS & ROE CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
References
REF-PT21-83-058-000 83-15, BRGO-RO-83-015, BRGO-RO-83-15, PT21-83-058-000, PT21-83-58, NUDOCS 8311290193
Download: ML20086C861 (3)

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@ OO ~h D g Burns and Roe,Inc.

601 Wi!liam: Bculevard a Richland, Washington 99352 a Tet (509) 943-8200

Subject:

Work Order 3900-4000 Washington Public Power Supply System WNP-2 y,in off,c, Room Pressurization Due To High Energy 550 Kinderkamsck Road Line Break Oradell, New Jersey 07649 Responds to: NA (20 0 2652000

Reference:

BRGO-RO-83-013 November 18, 1983 BRGO-RO-83-015 Response Required: NA Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Attention: Director

Dear Sir:

The reference letter provided notification of a condition we considered potentially reportable under 10CFR21. That condition being a failure to update room pressurization calculations to reflect final design vent paths. We have completed our reanalysis and conclude that one room in the reactor building (R206C) cannot withstand calculated pressurization following a postulated high energy line break within the room. Therefore, we now consider the condition to be repartable under 10CFR21 and have so notified Mr. D. Haist of your Region V office on November 17, 1983.

Complete details are provided in the attached evaluation report.

A followup report will be provided to your office once we have determined what, if any, plant uodifications are required.

If you have any questions, please contact W.G. Conn at (509) 943-8241.

Very truly yours, WGC:lvs Attachment W.G. Conn cc: BPA - Mr. W.S. Chin Licensing Supervisor SS - Mr. G.L. Gelhaus, w/a SS - Mr. L.T. Harrold, w/a SS - Mr. J.G. Tellefson, w/a SS - Mr. R.T. Johnson, w/a NRC - Mr. J.B. Martin, w/a Region V a_an, n~ .u ,n, ij, 8311290193 831118 PLR ADOCK 05000397 S PDR I

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ROOM PRESSURIZATION DUE TO HIGH ENERGY LINE BREAKS #83-15 DESCRIPTION OF DEFICIENCY l

Plant modifications implemented for fire protection and other con-cerns included blocking of some vent paths from Reactor Building Rooms containing high energy lines. Room pressurization calcula-tions were not updated to reflect the revised venting capability.

SAFETY IMPLICATION Decreased vent area results in higher room pressure following a High Energy Line Break (HELB) which could cause wall / floor fai-

. lure with attendant damage to safety related components.

CAUSE OF DEFICIENCY Failure to recognize that reducing room vent paths could have adverse safety implications.

ACTIONS TO PREVENT RECURRENCE Group Supervisors have been advised that changes to room vent areas require consideration as to potential effect on room pres-surization calculations.

CORRECTIVE ACTION All Reactor Building Rooms containing high energy lines were evaluated as to vent area changes. Six rooms were determined to require reanalysis.

Subsequent reanalysis has shown that one room (R206C) cannot withstaad calculated pressurization following a postulated high energy line break (HELB). This room is actually a pipe chase that has one cement block wall for shielding purposes. Pres-surization following a HELB would cause the block wall to fail.

Impacts from falling cement' blocks could' damage safety related equipment, primarily electrical conduit. Failure of the block wall in no way affects structural integrity of the building.

To correct this condition, we will perforr a safe shutdown analysis assuming the loss of all safety related equipment that could be impacted by falling cement blocks and the loss of an additional

ROOM PRESSURIZATION DUE TO HIGH ENERGY LINE BREAKS #83-15 CORRECTIVE ACTION (continued)

- worst case single active component. If these assumed failures do not prevent reaching safe shutdown, no further action will be taken.

If, however,. safe shutdown in precluded, plant modifications will be issued to either i) protect or relocate necessary safety related equipment, or 11) modify the block wall to provide necessary venting.

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