ML20101C765
| ML20101C765 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 12/05/1984 |
| From: | Foster D GEORGIA POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| GN-490, IEB-84-03, IEB-84-3, NUDOCS 8412210187 | |
| Download: ML20101C765 (3) | |
Text
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Georgia Power Company 5
Route 2, Box 299A Waynesboro. Georgia 30830 -
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December 5, 1984 United States Nuclear Regulatory Commission
Reference:
Office of Inspection and Enforcement RII:
JPO:
Region II - Suite 2900 50-424, 50-425 101 Marietta Street, Northwest Atlanta, Georgia -30323 File:
X7BC24 Log:
GN-490 Attention: Mr. James P. O'Reilly 4
We are in receipt of I&E Bulletin 84-03, entitled " Refueling Cavity Water Seal."
In response to that Bulletin we have reviewed the design and installation procedure regardin for-the Vogtle Electric Generating Plant (VEGP)g refueling cavity ' seals Based upon our review we have determined that VEGP design mitigates the possibility of failure of these seals.
Our conclusions are based upon the following:
1.
The seal assembly is of the passive mechanical type, which uses a compressible gasket as the sealing madium (similar to a flat faced flange).
Therefore, the VEGP seal assembly is not subject to active failure mechanisms.
-2.
The seal consists of eight separate assemblies, each of which independantly seals a section of-the cavity vent between the inservice inspection ports; there is no overlap.
Unlike inflatable pneumatic seal assemblies, which generally -consist of one continuous plate (torus) covering the entire opening around the vessel, these separate assemblies are not subject to significant distortion or displacement which could induce seal leakage.
3.
The gaskets will be replaced prior to each use to ensure that the mechanical properties including leak tightness of the seal assemblies is maintained during the refueling operation.
Any leakage of the seal resulting from undetected damage to the gasket or assymetric torquing of the holddown bolts during seal installation would be directed to the reactor cavity sump.
The cavity sump is monitored by: redundant nonsafety-grade level switches and a single safety-grade level transmitter.
Seal leakage in excess of the sump pumps' capacity (100 gpm) would be alarmed in the control room when the sump reaches the high level.
8412210187 841205
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e Page.Two Although failure of the entire cavity seal is not considered probable, an.evaluatior, was performed assuming a failure of an 8-inch section of the ~ gasket between two adjacent holddown bolts.
The results of this evaluation are' summarized as follows:
1.
The initial flowrate 'into the reactor cavity sump would be approximately 175 gpm.
2.
The refueling canal is normally filled by using a residual heat removal (RHR) pump aligned to the refueling water storage tank.
Therefore, makeup capacity will be in excess of leakage for the duration of the event.
3.
Assuming fuel is being transferred when the seal fails, and no makeup to the refueling canal from the spent fuel pool or any other source,. it would take over 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> to -lower-the refueling _ canal water level (ten feet) enough to expose the top of the assembly being transferred.
This is sufficient time to place the assembly in a safe condition.
4.
The top of the fuel assemblies in the spent fuel pool are at the same elevation as the refueling cavity water seal.
Therefore, seal failure would not result in uncovering the stored spent fuel assemblies.
5.
The refueling cavity can be drained.down to the level of the refueling cavity seal in under two hours by using one RHR pump to return the water to the refueling water storage tank.
[:
Based on the above, it is Georgia Power Company's position that the current VEGP design is capable of mitigating a failure of the refueling cavity seal without uncovering fuel. Therefore, no corrective action relative to I&E Bulletin 84-03 is considered necessary.
This response contains no proprietary information and may be placed in the NRC Public Document Room.
Yours truly,
/
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. Foste REF/D0F/tdm
Page Three D. O. Foster states-that he is the Vice President and Project General Manager of-the Vogtle Electric Generating Plant and. is authorized to. execute this oath on behalf of Georgia Power Company and that to the best.of his knowledge and belief the facts set forth in this letter are true.
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Sworn and subscribed before me this f day of December, 1984.
T i t' o t Y
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' NotWry Public, State of Georgia at Large Mi Commission Expires:
10/26/88 Nc:ur D_
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U. S. Nuclear Regulatory Commission Document Control Desk Washington, D. C.
20555 R. J. Kelly J. A. Bailey G. Bockhold R. E. Conway
- 0. Batum P. D. Rice G. F. Head H. H. Gregory C.'S. McCall-(0PC)
J. T. Beckham W. T. Nickerson E. L. Blake, Jr.
R. A. Thomas D. R. Altman (Shaw, et. al.)
D. E. Dutton D. L. Kinnsch (BPC)
J. E. Joiner W. F. Sanders (NRC)
J. L. Vota (W)
(Troutman, et. al. )
R. H. Pir. son L. T. Gucwa D. C. Teper (GANE)
B. M. Guthrie C. E. Belflower L. Fowler (LEAF)
E. D. Groover M. Malcom (BPC)
T. Johnson (ECPG)
.