ML20045C085
| ML20045C085 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 06/14/1993 |
| From: | Fenech R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9306220061 | |
| Download: ML20045C085 (2) | |
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1 Tennessee Vakey Auwdy Post o%ce Bom Soody-Da sy. Tennessee 3737}2000 Robert A Fenech v,ce P<escent sequoyah reer Pian June 14, 1993 10 CFR 50.12 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:
In the Matter of
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328 SEQUOYAl. NUCLEAR PLANT (SQN) - ADDITIONAL INFORMATION REGARDING EXEMPTION-FROM 1C CFR 50.60, " ACCEPTANCE CRITERIA FOR FRACTURE PREVENTION MEASURES FOR LIGHWATER NUCLEAR POWER REACTORS FOR NORMAL OPERATION"
Reference:
TVA letter to NRC dated June 5, 1993, "Sequoyah Nuclear Plant (SQN) - Request for Exemption From 10 CFR 50.60, ' Acceptance Criteria for Fracture Prevention Measures for Lightwater Nuclear Power Reactors for Normal Operation'"
The purpose of this letter is to provide additional information to NRC to support review of-the referenced exemption letter. During a telephone conference on June 9, 1993, the staff requested that TVA' investigate SQN's low tentperature over-pressure protection (LTOP) setpoint margins when performing reactor coolant system (RCS) sweep and vent operations with less than four reactor coolant pumps-(RCPs).
Tie LTOP setpoint margin information provided in TVA's exemption' letter was based on four-pump operation.
IVA subsequently requested that Westinghouse Electric Corporation provide LTOP setpoint margins for two-and three-pump operation. The following provides the Westinghouse ' estimate of the available Lr0P potential error margins-(1.e.. estimated effect).for two-and three-pump operation:- For two-pump operation, the estimated.effect is 47.5 pounds per square inch (psi).. Two-pump operation with SQN's present LTOP setpoints would' require that-RCS temperature _ remain above.113 degrees Fahrenheit (F).for Unit 1 and 102 degrees F for Unit 2.
For three-pump operation, the estimated effect is 61.0 psi. Three-pump' operation would require that RCS temperature remain above 158 degrees F for Unit 1 and 110 degrees F for. Unit 2.
The above information was discussed with the staff during 9306220061.9202191
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p U.S. Nuclear Regulatory Commission Page 2 June 14, 1993 a telephone conference call on June 11, 1993. TVA noted in the discussion that two-pump sweep and vant operation cannot ensure adequate purging of noncondensables and is therefore not an acceptable option.
In addition,1VA noted that the three-pump sweep and vent operation was allowed by the operating procedure.
A further constraint was identified to NRC with regard to the maximum temperature allowed for RCP start operation.
Specifically, in order.to minimize the pressure transient when starting a RCP, the RCS temperature must be less than the charging and seal injection water temperature. The charging and seal injection temperature limit is approximately 130 degrees F.
Therefore, three pump sweeps and vents are unacceptable for Unit 1.
Based on the above information, operational constraints prevent the utilization of administrative controls to ensure sufficient LTOP margins for Unit 1.
In order to provide consistency in design basis.between the units and minimize confusion on operational constraints, the exemption requested in the above reference is requested for application to both Units 1 and 2.
Please direct questions concerning this issue to J. D. Smith at (615) 843-6672.
Sincerely.
'l Robert A. Fenech cc:
Mr. D. E. LaBarge, Project Manager U.S. 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, Tennessee 37379-3624 I
Regional Administrator U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323-2711
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