ML20008F917

Final Deficiency Rept Re Reactor Pressure Vessel Level Sensing Lines,Initially Reported 800808.AE Has Completed Pipe Sleeve Extension to Recirculation Discharge Line Penetrations in Shield Wall.Corrections Completed 810601

ML20008F917
Person / Time
Site:	Grand Gulf
Issue date:	05/01/1981
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-81-159, NUDOCS 8105120326
Download: ML20008F917 (3)

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EdddhhhaB MISSISSIPPI POWER & LIGHT COMPANY Helping Build Mississippi P. O. B OX 1640 J AC K SO N, MIS SIS SIP PI 3 9 2 05 J^$yff&ujygfjR May 1, 1981 ,

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U. S. Nuclear Regulatory Cocunission g7 jgg y Region II .

101 Mariett.t Street, N.W.

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Suite 3100 Aclanta, Georgia 30303 4 e3 W

Attention: Mr. J. P. O'Reilly, Director

SUBJECT:

Grand Gulf Nuclear Station Units 1 and 2 Docket Nos. 50-416/417 File 0272/15525/15526 PRD-80/48, RPV Sensing Lines, Final Report AECM-81/159

Reference:

AECM-80/209, dated 9/8/80 On August 8, 1980', Mississippi Power & Light Company notified Mr. M.

Hunt, of your office, of a Potentially Reportable Condition (PRD) regarding the possibility of reflective insulation in the annular space between the reactor vessel and shield dislodging during a loss of coolant accident (LOCA) and shearing Reactor Pressure Vessel level sensing lines.

We have since determined that the deficiency is reportable within the i

meaning of 10CFR50.55(e). The deficiency is not reportable under 10CFR21 as l the component has not been accepted by Mississippi Power & Light. Our final report is attached.

l Yours truly, l

g [ J. P. McGaughy, Jr.

ATR:dr Attachment ec: See page 2 g

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Member Middle South Utilities System 810 512 0 3RG

Mr. J. P. O'Reiliv AECM-81/159 NRC Page 2 cc: Mr. N. L. Stampley Mr. R. B. McGehee Mr. T. B. Conner Mr. Victor Stello, Director Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Mr. G. B. Taylor South Miss. Electric Power Association P. O. Box 1589 Hattiesburg, MS 39401 e

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Attachment to AECM-81/159 Page 1 of 1 Final Report For PRD-80/48 I. Description of the Deficiency If a Loss of Coolant Accident (LOCA) were to occur at the Grand Gulf Nuclear Station (GGNS), the reflective insulation in the annular space between the reactor vessel and shield wall could dislodge and produce missiles sufficient to shear any of the one-inch vessel level sensing lines. The potential for this condition exists in the LOCA case where a slot break occurs in one of the twelve reactor recirculation pump dis-charge lines. The force of the escaping steam and water could create pressure waves spreading around the reactor vessel and shield wall.

These pressure waves could cause pieces of the reflective insulation to break off and become missiles. This event is known as annulus pressur-ization (AP).

This deficiency involves the Vessel Instrumentation System of the Nuclear Boiler System and is applicable to Units 1 and 2.

II. Analysis of Safety Implications Present analysis cannot determine or predict which reactor vessel sensing lines would be fractured during an annulus pressurization (AP) event. It has been determined that a condition could exist wher t a ' loss ,

of these one-inch level sensing lines could have adversely affected the safe operation of the plant.

III. Corrective Actions Taken The Architect / Engineer has completed the design of a pipe sleeve exten-sion to the recirculation discharge line penetrations in the shield wall

- to protect the insulation panels from the effects of a jet force. The l pipe sleeve is extended beyond the insulation panels and will divert the maximum pressure created by the LOCA from the insulation.

The corrective actions described above will also preclude recurrence.

It is expected all corrective actions. vill be completed by June 1, 1981.

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