ML20133P739
| ML20133P739 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 10/29/1985 |
| From: | Withers B PORTLAND GENERAL ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20133P732 | List: |
| References | |
| TAC-60095, NUDOCS 8511010165 | |
| Download: ML20133P739 (3) | |
Text
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s PORTLAND GENERAL ELECTRIC COMPANY EUGENE WATER & ELECTRIC BOARD l
AND i
PACIFIC POWER & LIGHT COMPANY i
Operating License NPF-1 Docket 50-344 License Change Application 134 This License Change Application requests modifications to Operating License NPF-1 for the Trojan Nuclear Plant to revise the minirnum water level to be maintained in the condensate storage tank.
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PORTLAND GENERAL ELECTRIC COMPANY By
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Bart D. Withers Vice President Nuclear Subscribed and sworn to before me this 29th day of October 1985.
n, Notary Public of Oregsiin My Commission Expires:
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8511010165 851029 PDR ADOCK 050 4
P i
LCA 134 Page 1 of 2 i
REASON FOR CHANGE Recent difficulties with the Auxiliary Feedwater (AFW) System have indi-4 l
cated that the safety-related AFW pumps are prone to low suction pressure trips on startup if the condensate storage tank (CST) level is less than 60 percent, particularly if both pumps are started simultaneously. A Temporary Plant Test verified that both pumps could be started simul-taneously from an automatic initiation signal, and would continue to run and perform their design functions, if minimum CST level (when the pumps are started) was limited to 60 percent indicated.
The minimum allowable level (for Modes 1, 2, and.3) was increased to 70 percent to account for instrument error and for the static hea6 provided by the water in the.
suction pressure transmitter reference leg. From the Control Room Curves and Tables Manual, 70-percent level corresponds to a minimum contained volume of 325,000 gallons.
1bs stat'ed in our letter of August 12, 1985, we do not consider this Technical Specification change to be necessary. A minimum CST level of 70 percent is being incorporated into Plant operating procedures as a limit below which one AFW pump will be declared inoperable, and the Action Statement of Technical Specification 3.7.1.2, Auxiliary Feedwater System will be implemented. Action Statement a of Technical Specifica-tion 3.7.1.2 requires that, with one of the two safety-related AFW pumps inoperable, the inoperable pump must be restored to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or the Plant placed in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
Submittal of this Technical Specification change (to a minimum CST level of 60 percent) was requested by the USNRC in your letter of September 13, 1985 (E. J. Butcher to B. D. Withers).
DESCRIPTION OF CHANGE i
Page 3/4 7-8. TTS 3.7.1.4. Condensat e Storage Tank The minimum contained volume in the CST during operation in Modes 1, 2, and 3 is changed from 196,000 to 222,000 gallons. As described in the revised Bases for Technical Specification 3.7.1.4, the specification
-mandating 196,000 gallons does not account for instrument error and the unusable volume in the CST. A footnote is added to Technical Specifica-tion 3.7.1.4 explaining that an interim minimum CST level of 70 percent (325,000 gallons) will be maintained in the CST until modifications to the AFW System, including alterations to prevent spurious low suction pressure AFW pump trips, are completed.
Pane B 3/4 7-2a. Bases 3/J.7.1.4 t
The Bases section for Technical Specification 3.7.1.4 has been expanded f
to identify the component:s of the 222,000 gallons minimum CST level. The L
interim minimum CST level of 70 percent (325,000 gallons) is also explained in the revised Bases.
e LCA 134 Page 2 of 2
~SIGNIFICANT HAZARDS CONSIDERATION In a letter to the NRC of August 12, 1985 (B. D. Withers to E. J. Butcher).PGE has already committed to maintaining 160-percent
-level.in the CST by administrative controls. As noted in that letter, increasing the minimum operating level in the CST to 60 percent does not constitute aus unreviewed safety question because the probability of occurrence or the. consequences of an accident or malfunction of equipment important'to safety previously evaluated in the safety analysis report is not increased. Raising the CST minimum water level to 60 percent decreases the probability and the consequences of an accident or malfunc-tion of equipment important to safety. A level of 60 percent provides greater assurance that both AFW pumps will automatically start and operate, and provides a greater volume of water in the CST for heat removal. These discussions also apply to increasing the minimum operating level in the CST to 70 percent.
The possibility for an accident or malfunction of a different type than any evaluated-previously in the safety analysis report is not created by increasing the minimum CST level to 70 percent. A minimum level of 70 percent provides additional conservatism and does not create the possibility for an accident or a malfunction of a different type than evaluat ed previously.
-Also, the margin of safety defined in the basis for any Technical Speci-fication has not been reduced by this increase in minimum CST level. The margin of safety is increased by this change.
Based on the above, this Technical Specification change does not involve a.significant hazards consideration.
SAFETY / ENVIRONMENTAL EVALUATION.
Safety and environmental evaluations were performed as required by 10 CFR 50 and the Trojan Technical Specifications. This review deter-mined that an unreviewed safety question does not exist since Plant operations remain consistent with the Updated FSAR, adequate surveillance is maintained, and there is no conceivable impact upon the environment.
SCHEDULE CONSIDERATIONS None.
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