ML20195C810

Safety Evaluation Supporting Amend 86 to License DPR-25

ML20195C810
Person / Time
Site:	Dresden
Issue date:	05/27/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20195C798	List: ML20195C795 ML20195C810
References
NUDOCS 8605300609
Download: ML20195C810 (2)

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NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 1

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 86 TO FACILITY OPERATING LICENSE N0. DPR-25 COMMONWEALTH EDISON COMPANY DRESDEN NUCLEAR POWER STATION, UNIT NO. 3 DOCKET NO. 50-?49

1.0 INTRODUCTION

By letter dated March 31, 1986, Commonwealth Edison Comoany (the licensee) made application to amend the Technical Specifications (TS) of Dresden Station Unit 3 to revise the high flow isolation setooint for the unit's Isolation Condenser (ISCO) Return Line. The change is required because of a replacement of the existing elbow taos for sensina flow rates in the return line with an annubar flpw element located at a different point in the line. This is being done during the current Recirculation Pipe Replacement Outage. Because of this modification, the trip level settings are being changed to 14.8" H 0 p

differential from the previous 32" differential. This is merely a number '

chance due to differences in instrumentation and does not alter the function of the ISCO system to automatically isolate from the reactor at 300 percent normal flow due to a line break.

In addition, the Limitina Condition for Operation (LCO) Bases page (3/4.2-31, second paragraph) pertaining to the ISCO return and supply lines differential pressure sensors is being clarified.

2.0 EVALUATION The annubar flow element, which is a pitot tube, would be installed in the straight portion of the vertical pipina section closest to the reactor vessel.

This would prevent its installation from impacting the normal stresses already existing in nearby elbows and the staff finds this installation point acceptable. The present trip level settina of 32" water differential pressure for the ISCO condensate return line high flow would be changed to 14.8" differential to correspond to the change in instrumentation. The licensee indicated that the original 32" differential corresponds to a high flow rate of 2508 gpm which is 300 percent of the normal 1500 return line flow of 836 gpm and is the original General Electric design for ISCO isolation. The 2508 gpm number was used to calculate the 14.8" H 0 p

differential setpoint for the new annubar. The staff agrees that this is merely.a number change due to differences in instrumentation and does not change the function of the ISCO system to automatically isolate from the reactor at 300 percent normal flow due to a line break. The use of the new number is therefore acceptable.

The licensee has rewritten the second sentence of the second paragraph of the LC0 bases page 3/4.2-31 to clarify that there are two sensors on the supply line and two sensors on the return line and that any one of the four sensors can cause system isolation.

In the third sentence, "20 psig" is being changed to "20 osi" and the word " differential" is being added following "14.8 inches of water". The staff finds these changes acceptable.

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3.0 ENVIRONMENTAL CONSIDERATION

This amendment inv.olves a change to a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The staff has determined that the amendment involves no significant increase in the amounts, and no significant cFanae in the types, of any effluents that may be released offsite and t':at there is no significant increase in individual or cumulative occupational <1diation exposure. The Commission has previously issued a proposed find'nq that this amendment involves no significant hazards consideration and there has been no public comment on such finding.

Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 30 CFR 51.22(c)(9). Pursuant to 10 CFR 51.?2(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.

4.0 CONCLUSION

The staff has concluded, based on the considerations discussed above, that:

(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the oroposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security nor to the health and safety of the public.

Principal Contributor:

R. A. Gilbert Dated:

May 27, 1.986.

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