ML20071H897

Second Interim Deficiency Rept Re Thermal Cycling of Reactor Vessel Head During Hot Operations,Initially Reported on 811201.Investigation Continuing.Deficiency Not Reportable Per 10CFR50.55e.Final Rept Will Be Submitted by 820416

ML20071H897
Person / Time
Site:	Grand Gulf
Issue date:	02/19/1982
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-82-67, NUDOCS 8203080574
Download: ML20071H897 (4)

Text

= - .

=

MISSISSIPPI POWER & LIGHT COMPANY Helping Build Mississippi.

P. O . B O X 16 4 0, J A C K S O N, MIS GIS S I P PI 3 9 2 0 5 i EiidrYE'/r de66taty.19'7

' - ;J 982

,go 0)

Of fice of Inspection & Enforcement t*'

U. S. Nuclear Regulatory Commission 9 Region 11 $'[ F.ECBVED 101 Marietta Street, N.W. Q g Suite 3100 c5 MAR 051982> - '

gym' Atlanta, Georgin 30303 -

suurat mirms u /g Attention: Mr. J. P. O'Reilly, Regional Administrator y * "

Dear Mr. O'Reilly:

4 _ pa

SUBJECT:

Grand Gulf Nuclear Station Units 1 and 2 Docke t Nos. 50-416/417 File 0260/15525/15526 PRD-81/49, Interim Report No. 2, Thermal Cycling of Reactor Vessel Head During Hot Operations AECM-82/ 67 On Decenber 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. 'Ihe deficiency concerns thermal cycling of the reactor vessel head during Hot Operations We svaluated the deficiency and concluded that it was not reportable under the provisions of 10CFR50.55(c). The deficiency and the rationale for considering it not reportable were discussed with Mr. Cantrell when the commission has first notified of he deficiency 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(c) format.

MP&L has requested General Electric to make a formal review of the inci-dent. It is expected that this review will be received from GE and a final written report vill be made to the NRC by April 16, 1982.

Attached is our Interim Report No. 2.

Yours truly, 1

8203080574 820219 V PDR ADOCK 05000416 S PDR J. P. McGaughy, Jr.

KDS:dr . - w _.~.

ATTACHMENT Oy}rICIACCOPY {

Member Middle South Utilities System --

o ..

l Mr. J. P. O'Reilly AECM-82/ 67 NRC Page 2 cc: Mr. N. L. Stampley Mr. R. B. McGehee Mr. T. B. Conner Mr. Richard C. DeYoung, 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 A

s

Attach::nt to AECM-82/67 P:go 1 of 2 INTERIM REPORT No. 2 FOR PRD-81/49 I. Description of the Deficiency During Hot Operations testing, November 5-10, 1981, the reactor vessel bottom head experienced a number of thermal transients. The transients occurred as a result of actions taken to reduce the amount of temperature stratification in the reactor vessel bottom head region. Several of these exceeded the Grand Gulf FSAR and Technical Specification limits of 100 F/hr. average rate of change of coolant temperature during normal hentup and cooldown. The maximum change in one hour period was 148 F.

This deficiency affected System B21, the Nuclear Boiler System for Unit 1 only. Unit 2 was not affected.

The potential exists that the large rate of change of the vessel bottom head metal temperatures may have caused stresses in excess of those for which the bottom head was designed.

Initial evaluations by both General Electric and MP&L indicate that this incident, combined with the normally expected 10% usage of thermal design margin during operations, should have no detrimental effect. However, a formal review is being conducted by General Electric.

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 lower head region.

General Electric, the designer of the NSSS, is conducting a detailed analysis to determine effects on safety of operations of the nucles-power plant due to the thermal transients that occurred.

III. Status of Proposed Resolution General Electric, the NSSS vendor, 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.

Guidelines were issued by General Electric to prevent recurrence during the remainder of the testing. These guidelines identified how to help

. prevent the temperature stratification and what to do if it occurred.

System Operating Instruction (SOI) No. 04/01-B33-1 will be revised prior to fuel load to. include a requirement to have the Flow Control Valve at the maximum flow position when running one recirculation pump on the low frequency motor generator. Also, during operation, the temperature interlocks have to be operational and the temperature differentials met in order for there to be a change in pump speed or to start a pump.

Attach 2snt to AECM-82/67 Page 2 of 2 IV. Reason Why a Final Report Will be Delayed Mississippi Power & Light has not received the results f rom General Electric of their detailed review. This is expected to be completed by March 12, 1982.

V. Date When Final Report Will be Submitted We expect to submit a Final Report by April 16, 1982.