ML20237J959
| ML20237J959 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 08/06/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20237J955 | List: |
| References | |
| NUDOCS 8708190029 | |
| Download: ML20237J959 (2) | |
Text
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NUCLEAR REGULATORY COMMISSION 3
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-K WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION 1
SUPPORTING AMENDMENT N0.102 TO FACILITY OPERATING LICENSE NO. DPR-29 l
AND AMENDMENT NO. 99 TO FACILITY OPERATING LICENSE N0. DPR-30 l
COMMONWEALTH EDIS0N COMPANY AND IOWA-ILLIN0IS GAS AND ELECTRIC COMPANY i
QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 DOCKET NOS. 50-254/265
1.0 INTRODUCTION
By letter dated May 14, 1986 Commonwealth Edison Co (Ceco, the iicensee) l proposed to amend the Quad Cities Nuclear Power Station (Units 1 and 2)
Technical Specifications (TS). The amendments would incorporate i
operability and surveillance requirements for the comon unit 4-KV Bus Cross-tie into TS 3.9/4.9 (Auxiliary Electrical Systems). The necessity I
for these additional TS requirements came as result of an event at Dresden 2.
During the August 16, 1985 Dresden 2 event, normal offsite AC power was lost due to tripping of the Reserve Auxiliary Transformer (RAT) which was being fed by the 138-KV switchyard.
Due to a transfer circuit deficiency, the two auxiliary power buses normally fed by this transformer failed to automatically transfer to the Unit Auxiliary Trnsformer (UAT) which was the second normal supply of AC power (from ot. Jt of Main Generator).
This failure to transfer ultimately led to a eactor scram and loss of Main Generator AC power to the UAT, constituting a complete loss of offsite AC power. As designed, both diesel generators automatically started providing AC power to essential equipment.
During this event, another independent source of offsite power was available (but not utilized) via the Unit 2/3 4-KV Bus Cross-tie.
2.0 EVALUATION GDC 17 of 10 CFR 50 Appendix A requires that electric power from the transmission network to the onsite electric distribution system shall be supplied by two physically independent circuits. By letter dated December 13, 1985, the licensee stated that the RAT of the other Dresden unit, supplied through a bus tie between corresponding safety-related buses of units 2/3, was the second of fsite source of electric power mandated by GDC-17. Although this specific back-up source of offsite 8708190029 870806 DR ADOCK OSO 4
. power is not automatically transferred, it could be aligned quickly from the control room.
Futhermore, offsite power capability via the cross-tie has been designed with sufficient capacity to operate one plant's total auxiliary loads during normal operation, while supplying adequate power to safely shutdown the other plant and also support all necessary engineered safeguards during an accident. This eletrical configuration is essentially the same at Quad Cities 1/2.
However, existing TS 3.9.A only requires the 4-KV cross-tie, for Quad Cities 1/2, to be available if normal offsite power to one of the two i
units is lost.
In a response dated December 13, 1985, to address j
concerns raised by the staff about compliance with GDC 17, the licensee 1
comitted to amend TS 3.9 for Dresden and Quad Cities.
Subsequently by letter dated May 14, 1986, the licensee proposed changes to TS 3.9 which would establish operability and surveillance requirements for the comon unit 4-KV cross-tie and thereby as:sure an alternative source of offsite AC power would be available.
In conclusion, the staff has reviewed the proposed TS and considers them acceptable requirements for ensuring availability of a second independent back-up source of offsite power via the 4-KV bus cross-tie that is consistent with GDC 17.
3.0 ENVIRONMENTAL CONSIDERATION
These amendments involve a change to the operability and surveillance requirements of a facility component located within the restricted area as defined in 10 CFR Part 20. The staff has determined these amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite an: there is no significant increase in individual or cumulative occupational radiation exposure. The Comission has previously issued a proposed finding of no significant hazards consideration for these amendments and there has been no public comment on such finding. Accordingly, these amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuantto10CFR51.22(b)noenvironmentalimpactstatementorenvironmental assessment need be prepared in connection with the issuance of these amendments.
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 puulic will not be endangered by operation in the proposed manner, and (2)
I such activities will be conducted in compliance with the Comission's regulations and the issuance of these amendments will not be inimical to j
the comon defense and security or to the health and safety of the public.
j 1
Principal Contributor:
N. Trehan Dated: August 6, 1987 m