ML20092M744
| ML20092M744 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 09/26/1995 |
| From: | Shell R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9510030311 | |
| Download: ML20092M744 (5) | |
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' Tennessee Valley Autho,ny. Post Ofhce Box 2000. Soddy-Desy. Tennessee 37379 September 26,1995 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:
In the Matter of
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Docket No. 50-327 Tennessee Valley Authority
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SEQUOYAH NUCLEAR PLANT (SON)- ADDITIONAL INFORMATION FOR TECHNICAL SPECIFICATION (TS) CHANGE 95-15, REVISION 1 i
Reference:
TVA letter to NRC dated September 7,1995, "Sequoyah Nuclear Plant (SON) - Technical Specification (TS) Change 95-15, Revision 1, ' Alternate Plugging Criteria for Steam Generator (S/G) Tubing - Unit 1'"
Enclosed is additionalinformation for TS Change 9515, Revision 1 that was discussed with the NRC staff during a September 19,1995, telephone call. The additionalinformation provides the new assumed initial value for secondary coolant iodine activity in the accident analysis associated with the subject TS change. The new value (0.1microcuries per gram dose equivalent lodine-131) replaces the current value (2x108 microcuries per gram dose equivalent lodine-131) that was assumed in Westinghouse Electric Corporation WCAP-13990. Accordingly, with the new assumed initial secondary side activity, the allowed S/G leakage rate from the faulted loop has been revised from 4.3 gallons per minute (gpm) to 3.7 gpm.
This change was evaluated by TVA and Westinghouse and is discussed in. Enclosure 2 provides a revised TS Bases page (Insert 1) that contains the new 3.7 gpm value. The new Insert Iinformation supersedes the Insert I previously provided in Enclosure 1 of the referenced letter.
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j September 26,1995 Please direct questions concerning this issue to D. V. Goodin at extension 7734.
- Sincerely, IR.H.2/A' R. H. Shell 1 Manager SON Site Licensing.
Enclosures cc (Enclosures):
Mr. D. E. LaBarge, Project Manager i
Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739 NRC Resident inspector Sequoyah Nuclear Plant
. 2600 Igou Ferry Road Soddy-Daisy, Tennesseo 37379-3624 5
Regional Administrator U.S. Nuclear Regulatory Commission Region 11 101 Marietta Street, NW, Suite 2900 1
Atlanta, Georgia 30323-2711' o
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f ENCLOSURE 1 STEAM GENERATOR ALLOWABLE LEAK RATE RECALCULATION I
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.SEP 22 '95 04:15PM WESTINGHOUSE
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TVA-95-195 September 22,1995 Mr. Mark Burzynski, Manager Department ofNuclear Engineering Tennessee Valley Authority Sequoyah Nuclear Plant
'P.O. Box 2000 SoddyDaisy,TN. 37379 Tennessee Valley Authority SequoyahNuclear Plant S/G Allowable Leak Rate Recalculation
Dear Mr. Burzynski:
The following provides the documentation for completion of task N95-024.
An evaluation has been performed to determine the maximum permissible steam generator primary to secondary leak rate during a steam line break for Sequoyah Nuclear Plant. Unit 1 and 2.This evaluation is identical to the evaluation presented in WCAP-13990,"Sequoyah Units 1 and 2 Steam Generator Tube Plugging Criteria for Isdications at Tube Supports Plates" with the exception of the initial secondary coolant iodine activity. The WCAP used a calculated concentration of 2 E-06 micro curie / gram of dose equivalent I-131. This evaluation uses a value of 0.1 micro curie / gram of dose equivalent I-131, to be consistent with the Standard Westinghouse Technical Specifications.
The result of this change is to slightly reduce the allowable leak rate. The previous leak rate was 4.6 gpm total or 4.3 gpm to SG on the faulted loop. The new leak rate is 4 gpm total or 3.7 spm to the fauhed loop.
If you have questions, please contact the undersigned.
Ve truly yours,
. W. Salak Sequoyah Projects Manager TVA Projects
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cc: D.Lafever
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ENCLOSURE 2 REVISED INSERT I FOR TECHNICAL SPECIFICATION CHANGE 95-15, REVISION 1 l
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insert I The total steam generator tube leakage limit of 600 gallons per day for all steam generators and.150 gallons per day for any one steam generator will minimize the i
. potential for a significant leakage event during steam line break. Based on the NDE '
uncertainties, bobbin coil voltage distribution and crack growth rate from the previous inspection, the expected leak rate following a steam line rupture is limited to below 3.7 gpm in the faulted loop, which will limit the calculated offsite doses to within 4
' 10 percent of the 10 CFR 100 guidelines. If the projected end of cycle distribution of crack indications results in primary-to-secondary leakage grecter than 3.7 gpm in the faulted loop during a postulated steam line break event, additional tubes must be removed from service in order to reduce the postulated primary-to-secondary steam line break leakage to below 3.7 gpm.
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