ML20045C917
| ML20045C917 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 06/21/1993 |
| From: | Shiraki C Office of Nuclear Reactor Regulation |
| To: | Farrar D COMMONWEALTH EDISON CO. |
| Shared Package | |
| ML20045C918 | List: |
| References | |
| TAC-M85079, TAC-M85080, NUDOCS 9306250093 | |
| Download: ML20045C917 (4) | |
Text
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June 21, 1993 Docket Nos. 50-295 and 50-304 Mr. D. L. Farrar Manager, Nuclear Regulatory Services Commonwealth Edison Company Executive Towers West III, Suite 500 1400 OPUS Place Downers Grove, Illinois 60515
Dear Mr. Farrar:
SUBJECT:
ZION STATION, UNITS 1 AND 2, CHANGE OF TECHNICAL SPECIFICATIONS BASES PAGE TO CORRECT THE DISCUSSION OF FUEL OIL REQUIREMFNTS IN BASES SECTION 3.15 (TAC NOS. M85079 AND M85080)
By letter dated November 18, 1992, Commonwealth Edison Company (Ceco) informed the staff that it was proposing a revised page 273 to the Technical Specifications (TS) for Zion Station, Units 1 and 2.
The changes are in response to unresolved items (295/92003-05 and 304/92003-05) in Inspection Report 50-295/92003 and 50-304/92003 regarding the Diesel Generator fuel Oil Transfer and Storage System.
Ceco's response to the unresolved item (in a letter dated April 15, 1992) indicated that the corrective action for this item would include a revision of the TS Bases Section 3.15, to be completed by October 1, 1992.
In a letter dated October 2, 1992, the completion date was extended to November 30, 1992, to allow time to incorporate the Bases change into a comprehensive upgrade to TS 3/4.15.
In another letter dated November 18, 1992, Ceco stated that due to the magnitude of the comprehensive change, the change to TS 3/4.15 would not be ready for submittal by November 30, 1992, and that to satisfy the original commitment, the Bases were being revised independent of submittal of the comprehensive TS amendment request.
The staff has completed its review of CECO's submittal and believes that it has adequately addressed the concerns expressed by unresolved items 295/92003-05 (applicable to Unit 1) and 304/92003-05 (applicable to Unit 2), and finds the actions taken to be acceptable.
However, to fully resolve this issue, CECO should confirm that the emergency diesel generator (EDG) fuel consumption rates which were calculated in its load study are conservative compared to the actual fuel consumption rate (corrected to account for the lowest quality diesel fuel allowed for EDG application) over the entire load range that is anticipated following an event, not just for the rated load condition.
The staff's safety evaluation is included as Enclosure 1.
The proposed change to the Bases constitutes an acceptable method of correcting the discussion of diesel generator fuel oil requirements in Bases Section 3.15 of the TS.
The staff, therefore, finds your proposed Bases
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Mr. D. L. Farrar change acceptable. The revised page is enclosed with this letter and s00 id be used to replace the current page.
Sincerely, gl,nalSigfied Of Clyde Y. Shiraki, Senior Project Manager Project Directorate III-2 Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation
Enclosure:
Revised Bases page 273 to Zion Station, Units 1 and 2, Technical Specifications cc w/ enclosure:
see next page DISTRIBUTION Docket File NRC & Local PDRs PDIll-2 r/f PDIll-2 p/f JRoe JZwolinski JDyer CMoore CShiraki OGC ACR$(10)
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Mr. D. L. Farrar Zion Nuclear Power Station-Commonwealth Edison Company Unit Nos. 1 and 2 cc:
f Michael I. Miller, Esquire Sidley and Austin One First National Plaza Chicago, Illinois 60603 Dr. Cecil Lue-Hing Director of Research and Development Metropolitan Sanitary District of Greater Chicago 100 East Erie Street Chicago, Illinois 60611 l
l Phillip Steptoe, Esquire Sidley and Austin One First National Plaza Chicago, Illinois 60603 Mayor of Zion Zion, Illinois 60099 i
i Illinois Department of Nuclear Safety Office of Nuclear Facility Safety 1035 Outer Park Drive Springfield, Illinois 62704 U. S. Nuclear Regulatory Commission
.I Resident Inspectors Office 105 Shiloh Blvd.
.l Zion, Illinois 60099 i
Regional Administrator, Region III U. 5. Nuclear Regulatory Commission 799 Roosevelt Road, Bldg. #4 Glen Ellyn, Illinois 60137 Robert Neumann
' Office of Public Counsel State of Illinois Center l
100 W. Randolph Suite 11-300 t
Chicago, Illinois 60601 l
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An inoperable engineered Safeguards 4160-volt bus results in the inoperability of the safcguards compon:nts supplied by this bus (See Table 3.15.2).
If the equipment supplied by the other two Safeguards 4160-volt buses remains operable (See Table 3.15.1), sufficient components are available for safe shutdown and decay heat removal following a loss of coolant accident and/or loss of off-site power, but redundancy has been lost.
The required available equipment stated in the Specification are consistant with those of the remaining operable Engineered Safeguard components.
The battery charger can carry the DC load of its bus independently of the battery.
In addition, a crosstle is available from a corresponding bus on the other unit; this tie can be utilized to maintain bus voltage and allow safe unit shutdown if the charger and battery are unavailable.
Since the battery charger can carry the bus, and since a backup source of power is available for shutdown should the charger be lost, the battery may be inoperable for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> without loss of control power for the engineered safeguards features.
If a battery charger were to fall, the proper state of charge can be maintained on the failed charger's tattery by closing the cross-tit breakers to the other unit's battery bus and utilizing that battery charger to maintain the proper state of charge on both batteries.
x$5 Operation with a Unit 1 and Unit 2 battery crosstied is permissible because a single failure will, at most, cause loss of control power to one of the three safeguards system on each unit; the two remaining systems are designed for safe shutdown and decay heat removal.
Because the independence of redundant systems is thus maintained, the requirements of Section 9 of IEEE 308-1971 are satisfied for this Inter-unit tie.
Under these conditions, a battery charger may be inoperable without unduly compromising the reliability of the safeguards systems.
Operating conditions or equipment maintenance may require one inverter to be Inoperable for brief periods.
During these periods, the instrument bus will be supplied by a 480/120 AC transformer.
Reference (1) discusses the ramifications if, during this period, a loss of off-site power and/or LOCA occurs and both units areaffectgd.
The probability of simultaneous loss of off-site power to both units is, however, estimated to be 5 x 10-for one occurrence over a forty year period; with this low a probability, one Inverter can be inoperable for a 14 day period without unduly compromising re11 ability.
The minimum fuel oli requirement of 40,000 gallons in each storage tank provides a 7 day supply for the associated diesel generator, assuming the diesel generator is under the worst case accident loading conditions.
The 40,000 gallon requirement includes not only the actual amount of fuel oli needed during the 7 days, but also accounts for the unusable amount of fuel oil due to tank design and a small margin.
(1) L. D. Butterfield letter of Dec. 1, 1972 to B. H. Grier in response to Regulatory Operations Bulletin 72-2.
273 revised by letter dated 6/21/93
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