ML20039F345

Interim Deficiency Rept Re Thermal Cycling of Reactor Vessel Head During Hot Operations,Initially Reported 811201.GE Analysis of Effect on Reactor Vessel Fatigue Cycle Lifetime Continuing.Final Rept Will Be Submitted by 820219

ML20039F345
Person / Time
Site:	Grand Gulf
Issue date:	12/31/1981
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-81-518, NUDOCS 8201120366
Download: ML20039F345 (3)

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MISSISSlPPl. POWER & LIGHT COMPANY

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1. $sSYNNsN[ December 31, 1981 Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Region II 101 Marietta St eet, N.W.

Suite 3100 Atlanta, Georgia 30303 Attention: Mr. J. P. O'Reilly, Regional Administrator

SUBJECT:

Grand Gulf Nuclear Station Units 1 and 2 Docket Nos. 50-416/417 File 0260/15525/15526 PRD-81/49, Interim Report No. 1, Thermal Cycling of Reactor Vessel Head During Hot Operations AECM-81/518 On December 1,1981, Mississippi Power & Light Company notified Mr. F. S.

Cantrell, of your office, of a Potentially Reportable Deficiency (PRD) at the Grand Gulf Nuclear Station (GGNS) construction site. The deficiency concerns thermal cycling of the reactor vessel head during Hot Operations Mississippi Power & Light evaluated the deficiency and concluded that it was not reportable under the provisions of 10CFR50.55(e). The deficiency and the rationale for considering it not reportable were discussed with Mr.

Cantrell when the deficiency was first reported on December 1, 1981. Mr.

Cantrell understood our rationale but considered the event to be of such significance that he requested MP&L to submit a detailed written report of the event in the 10CFR50.55(e) format.

MPSL has requested General Electric to make a formal review of t dent. It is expected that this review will be received from GE and written report will be made to the NRC by February 19, 1982. N Q

Attached is our Interim Report No. 1. ~/

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Mr. J. P. O'Reilly AECM-81/518 NRC Page 2 cc: Mr. N. L. Staapley Mr. R. B. McGehee Mr. T. B. Conner Mr.-Richard C. DeYoung, Director Office of Inspection & Enforcement' l U. S. Nuclear Regulatory Commission '

Washington,-D.C.'20555 Mr. G. B. Taylor South Miss. Electric Power Association i P. O. Box 1589 l Hattiesburg, MS 39401 9

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. . Attrchment to AECM-81/518 Pag-a 1 cf 1 4

INTERIM REPORT NO. 1 FOR PRD-81/49

1. Description of the Deficiency During Hot Operations testing, November 5, 1981, through November 10, 1981, the reactor vessel head experienced a number of thermal tran-sients. Several of these exceeded the Technical Specification limits of 100 F/hr cooldown rate. Active fuel elements were not installed in the reactor vessel at the time the transients occurred. At no time were pressure / temperature limitations of the technical specifications exceeded.

A formal review gf the known saf sty implications is being conducted by General Electric. This will also address the effects, if any, of the transient shortening the remaining thermal cycles available to the vessel during its lifetime.

II. Approach to Resolution of the Problem The transients occurred as a result of actions taken to reduce the amount of temperature stratification in the reactor vessel bottom head region.

Investigations are being undertaken to determine procedural changes that may be necessary to ensure that adequate continuous coolant flow is maintained to prevent thermal stratification in the lower head region.

III. Status of Proposed Resolution General Electric has been requested to perform a detailed analysis of the safety implications of the deficiency as well as the effect, if any, on the reactor vessel fatigue cycle lifetime.

IV. Reason Why a Final Report Will be Delayed Mississippi Power & Light has not received the results from General Electric of their detailed review.

V. Date When Final Report Will be Submitted We expect to submit a Final Report by February 19, 1982.