ML18233A117
| ML18233A117 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 07/01/1982 |
| From: | Dale L Mississippi Power & Light Co |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Algama D, D. Marksberry | |
| Shared Package | |
| ML18233A113 | List: |
| References | |
| 0272/0756/L-860.0 NUDOCS 8207020102 | |
| Download: ML18233A117 (4) | |
Text
uu.,m MISSISSIPPJ.;.8~~;~ ~;.~}.~;~p~ COMPANY
- [!l P. 0. BOX 1640. JACKSON, MISSISSIPPI 39205 NUCLEAR PRODUCTION DEPARTMENT U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, D. C. 20555 July 1, 1982 Attention:
Mr. Harold R. Denton, Director
Dear Mr. Denton:
Subject:
Grand Gulf Nuclear Station Units 1 and 2 Docket Nos. 50-416 and 50-417 rile 0272/0756/L-860.0 Hydrogen Control - Local Detonations and Drywell Head External Pressure Capacity AECM-82/315 In response to informally transmitted concerns of the Structural Engineering Branch Reviewer, Dr. C. P. Tan, Mississippi Power & Light Company is submitting information (Attachments 1 and 2) regarding local detonations and drywell head external pressure capacity. This letter supplements the information transmitted via AECM-82/118, dated March 31, 1982, and AECM-82/271, dated June 11, 1982, and confirms information provided to Dr. Tan on June 30, 1982.
If you have any further questions, please contact this office.
NSM/SHH/JDR:mm Attachments cc:
Mr. N. L. Stampley Mr. G. 8. Taylor Mr. R. 8. McGehee Mr. T. 8. Conner Mr. Richard C. DeYoung, Director Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D. C.
20555 PSD2R07020102 S20701 p
AD0Ck 05000416 PDR Yours truly,
~h L. F. Da 1 e Manager of Nuclear Services Member Middle South Utilities System
MISSISSIPPI POWER & LIGHT COMPANY Mr. J. P. 0 1 Reilly, Regional Administrator Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, N. W., Suite 3100 Atlanta, Georgia 30303 AECM-82/315 Page 2 to AECM-82/315 Leakage through Containment Personnel Airlock The lower containment personnel airlock has been analyzed for a local hydrogen detonation using the Sandia pressure-time curve.
The results of the analysis indicate that the maximum lateral deformation of the door panel on the airlock will be small albeit with a ductility ratio of less than 2.5.
For mid panel deformation of this magnitude, the performance of the inflatable seals at the periphery of the door will not be affected.
Considering the very short duration of the pressure pulse, it has been determined that there would be no leakage out of the containment when both doors on the airlock are in the closed position.
Leakage through the interior door, even when the leak path is postulated to be extremely severe, will be insufficient to overcome the pressurized seal on the exterior door.
In summary, neither the response of the airlock door due to the postulated local hydrogen detonation nor the response of the seals to the same detonation will initiate leakage out of the containment.
to AECM-82/315 Capacity of the Drywell Head under External Pressure The buckling capacity of the drywell head, which is comprised of an elleptical shell and a circular cylinder, has been evaluated using a conservative formulation developed at the David Taylor Model Basin (DTMB).
The critical external pressure for the elliptical head was calculated using the method given in the DTMB Report 1757, 11 The Effect of Initial Imperfections on the Collapse Strength of Deep Spherical Shells.
11 This method employs nominal dimensions and worst case deviations from nominal dimensions to determine the critical pressure, which was calculated to be 135 psi.
The critical external pressure for the cylinder was determined using the method given in the DTMB Report 1639, "Structural Analysis and Design Considerations for Cylindrical Pressure Hulls.
11 This method also employs nominal dimensions and worst case deviations from nominal dimensions to determine the critical pressure.
When the calculations were performed for a conservative out-of-roundness based on the out-of-roundness tolerance given on the manufacturing drawings, the minimum differential pressure capability of the cylinder was calculated to be 89 psi. However, when a best estimate of the out-of-roundness is used in the formulation, the minimum differential pressure was calculated to be 180 psi.
In summary, the buckling capacity of the drywell head has been evaluated using a formulation taking into account the effect of initial imperfections.
The lower bound estimate of 89 psi for the buckling capacity of the drywell head is based on a conservative assumption regarding such initial imperfections.