ML20010H396

Final Deficiency Rept Re Potential for Overpressurization of MSIV Drain Line Piping Initially Reported on 810218. Design Drawings Revised to Replace Overpressurized Piping & Valves for Both Units

ML20010H396
Person / Time
Site:	Grand Gulf
Issue date:	09/16/1981
From:	Mcgaughy J MISSISSIPPI POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
10CFR-050.55E, 10CFR-50.55E, AECM-81-356, NUDOCS 8109240420
Download: ML20010H396 (5)

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MISSISSIPPI POWER & LIGHT COMPANY

]U Helping Build Mississippi Edidabilid5 P. O. B O X 16 4 0, J A C K S O N, MI S SIS SIP PI 3 9 2 0 5

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Office of Inspection ; Enforcement ' C, U. S. Nuclear Regulate y Commission w t C

Region II D'  %@ -'

101 Marietta Street, N.W. [ O '

Suite 3100 iM @$t  % N Atlanta, Georgia 30303 \y

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Attention: Mr. J. P. O'Reilly, Director "' / j , , , . 7

Dear Mr. O'Reilly:

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SUBJECT:

Grand Gulf Nuclear Station Units 1 and 2 Docket Nos. 50-416/417 File 0260/15525/15526 PRD-81/10, Final Report, Possible MSIV Drain Line Overpressurization i AECM-81/356 l

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Reference:

AECM-81/113,3/20[81 On Ft.bruary 18, 1981, Mississippi Power & Light Company notified Mr. P.A. '

Taylor, of your office, of a Potentially Reportable Deficiency (PRD) at the Grand Gulf Nuclear Station (GGNS) construction site. The deficiency concerns the potential for overpressurization of the Main Steam Isolation Valve (MSlV)

Drain Line Piping.

We had previously determined that this condition is reportable under the provisions of 10CFR50.55(e), but not under 10CFR21 as reported in AECM-81/113, March 20, 19,81. . .-

Our final report giving corrective actions arl actiots to preclude recur-rence is attached.

Yours truly, J. P. McGaughy, Jr.

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ATTACHMENT /

cc: See , age 2 f /f N T!i ?'.% y(uq 81092404'20 010916 .

PDR ADOCK 05000416 Men oer Middle South Utilities System S PDR

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Mr. J. 0'Reilly AECM-81/356 NRC Page 2 cc: Mr. N. L. Stampley Mr. R. B. McGehee Mr. T. 3. Conner Mr. Victor Stello, Director Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Mr. G. B. Taylor S'uth Miss. Electric Power Association F. O. Box 1589 Hattiesburg, MS 39401 4

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bbe: Mr. D. C. Lutken Mr. J. Leatherman A

Dr. D. C. Gibbs Manager of BWR-6 Licensing Mr. . N. Ward General Electric Company .-

Mr. J. P. McGaughy, Jr. 175 Curtner Avenue Mr. J. D. Heaton -San Jose, CA. 95125 ,

Mr. R. Trickovic j

Mr. J. W. Yelverton ,

Mr. L. F. Dale- Mr. D. M. Houston Mr. C. K. McCoy U. S. Nuclear. Regulatory Commission Mr. T. H. Cloninger Division of Licensing Mr. R. A. Ambrosino Washington, D. C. 20555 Mr. A. J. Iosue - -

Mr. G. B. Rogers ,

1 Mr. S. H. Hobbs Mr. J, Matore Mr. L. E. Ruhland 1. S. Nuclear Regulatory Commission Mr. D. L. Hunt Division of Licensing Mr. A. G. Wagner [ Washington, D. C. 20555 Mr. P. A. Taylor '

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, , Attachment to AECM-81/356 Page 1 of 2 Final Report for PRD-81/10 I. Description of the Deficieucy The poter.tial exis*.s that the Main Steam Isolation Valve Drain Line piping between valves N1B21F021/F033 and Q1B21F113/F114 could be exposed to pressures greater than its designed pressure. This could be caused if valves F021 or F033 were open, passing condensate at main steam system pressure to valves F113 and F114. Concurrent with this, loss of BOP power would cause valves F113 and F114 to fail closed. Primary system pressure would then be imposed on some 3 inch HBD and 6 inch HBC lines. The piping is a common header for low point drain lines from the inside Mair steam Isolation Valves to the Main Condenser and is used for removing conac i *e generated during heatup and low power operation.

The failure of the piping could result in a degradation of the Auxiliary Build-ing isolation capability due to increased building pressure. This deficiency affects the Nuclear Boiler System (B21) and is applicable to both Unit 1 and Unit 2. It does not affect the NSSS vendor.

II. Analysis of Safety Implications During -operatior., while condensate / steam is flowing through valves F021/F033, an inadvertent closure of valves F113 or F114 would impose primary system pressure on various HBD and BBC piping downstream of F021/F033 as well as on valves F113 and/or F114. Valves F113 or F114 will close upon either loss of BOP power or loss of air to the valves (F113/F114 are Auxiliary Building isola-tion valves). A similar, but less likely, problem would result from an abnor-mal line-up (F113 or F114 closed) coincident with a loss of BOP power or air to F033 (fails open). '

This deficiency, resulting in degradation of the Auxilic y Building environ-ment, could affect the safety of operations of the nuclear power plant and is reportable under 10CFR50.55(e). Since the Nuclear Boiler System was not turned over to MP&L at the time the deficiency was detected, it is not reportable under 10CFR21. . .

III. Corrective Actions Taken The deficiency was caused by an oversight in the design. Our design agent os arlooked the impact of inadvertent closure of F113 or F114 and failed to design the piping and valves for the maximum operating conditions. The extent is limited to the Eain Steam Line Drain Piping, for the Nuclear Boiler System (B21).

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, , Attachment to AECM-81/356 Psgm 2 of 2 To correct the identified deficiencies design drawings have been revised to replace the cited overpressurized piping and valves. The 3 inch and 6 inch Sch 40 pipe was replaced with 3 inch and 4 inch Sch 80 pipe. The two auxiliary building isolation valves (Q1B21F113/F114) were also replaced with valves of the appropriate pressure rating. In addition, all connecting small piping and valves have been checked. The drain piping, to and including F114, is now capable of withstanding full primary system pressure. A review was also made of all piping which penetrates the auxiliary building to determine if a similar problem exists. This review verified that a similar problem does not exist in any other system. '

The drawing revision that has been issued for the piping and valve replacement covers both Unit I and Unic 2. -This will serve to prevent recurrence. The deficiency was determined to be an isolated incident which does not warrant changes to existing design control procedures. All corrective actions are scheduled to be completed by October 23, 1981.

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