ML17191B251
| ML17191B251 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 02/18/1999 |
| From: | Rossbach L NRC (Affiliation Not Assigned) |
| To: | Kingsley O COMMONWEALTH EDISON CO. |
| References | |
| TAC-MA1978, TAC-MA1979, NUDOCS 9902230351 | |
| Download: ML17191B251 (4) | |
Text
. '
Mr. Oliver D.. Kingsley, President NuGlear,r.;eneration Group
- - CGm111onw!lalth Edison Company
. -Executive. Towers West 111 1400 Opu,s Place, Suite 500.
Downers Grove, IL 60515
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- E'ebruacy 18, '1999. e
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SUBJECT:
TECHNICAL SPECIFICATIONS BASES CHANGE - DRESDEN.NUCLEAR POWER STATION, UNl~S 2 AND 3 (TAC NOS. MA1978 AND-MA1979)
Dear Mr. Kingsley:
.~,;
By letter dated April 15, 1998, as superseded by letter dated December 4, 1998, Commonwealth Edison Company (ComEd, the licensee) submitted a proposed change to*
Facility Operating License Nos.. DRP-19 and DRP-25, Appendix A - Technical Specifications (TS) Bases Section 3/4.9, "Electrical Power Systems." The licens~e made clarifying changes to the Bases section to describe the availability of an additional source of offsite power when backfeeding through the unit auxiliary transformer (UAT) of the shut down unit. Com Ed had previously performed a safety evaluation of this change in accordance with 10 CFR 50.59, determined that an Unreviewed Safety Question did not exist, and added this change to the Updated Final Safety Analysis Report.
These changes provide clarity to Bases Section 3/4.9 and the staff has no objections to this Bases change. Revised TS Bases page B 3/4.9-1 is enclosed.
Docket Nos. 50-237 and 50-249
Enclosure:
Page B 3/4.9-1 cc w/encl: See riext page DISTRIBUTION:
CT>ocket Fila?
S. Richards OGC, 015B18 G. Hill (4)
PUBLIC C. Moore ACRS, T2E26 W. Beckner Sincerely, Original signed by:
Lawrence W. Ros~bach, Project Manager Project Directorate 111~2 Division of Licensing Project Management Office*of Nuclear Reactor Regulation PDlll-2 r/f
- L. Rossbach M. Ring, Riii J. Zwolinski J. Calvo
- Concurrence provided by 1/6/99 memo; no major changes..
DOCUMENT NAME: G:\\PD3-2\\CM\\DRESDEN\\L TRA 19.78. WPD
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9902230351 990218,
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UNITED STATES NUCLEAR REGULATORY COMMISSION Mr. Oliver D. Kingsley, President Nuclear Generation Group Commonwealth Edison Company Executive Towers West Ill 1400 Opus Place, Suite 500 Downers Grove, IL 60515 WASHINGTON, D.C. 20555-0001 February 18, 1999
SUBJECT:
TECHNICAL SPECIFICATIONS BASES CHANGE-DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3 (TAC NOS. MA 1978 AND MA 1979)
Dear Mr. Kingsley:
By l~tter dated April 15, 1998, as superseded by letter dated December 4, 1998, Commonwealth Edison Company (ComEd, the licensee) submitted a proposed change to Facility Operating License Nos. DRP-19 and DRP-25, Appendix A-Technical Specifications (TS) Bases Section 3/4.9, "Electrical Power Systems." The licensee made clarifying changes to the Bases section to describe the availability of an additional source of offsite power when backfeeding through the unit *auxiliary transformer (UAT) of the shut down unit. Com Ed had previously performed a safety evaluation of this change in accordance with 10 CFR 50.59, determined that an Unreviewed Safety Question did not exist, and added this change to the Updated Final Safety Analysis Report.
These changes provide clarity to Bases Section 3/4.9 and the staff has no objections to this Bases change. Revised TS Bases page B 3/4.9-1 is enclosed.
Docket Nos. 50-237 and 50-249
Enclosure:
Page B 3/4.9-1 cc w/encl: See next page Sincerely,
- L-.~.11~
~~
W. Rossbach, Project Manager Project Directorate 111-2 Division of l,.icensing Project Management Office of Nuclear Reactor Regulation
- 0. Kings11~y Commonwealth Edison Company cc:
Commonwealth Edison Company Site Vice President - Dresden 6500 N. Dresden Road Morris, Illinois 60450-9765 Commonwealth Edison Company Dresden Station Manager 6500 N. Dresden. Road Morris, Illinois 60450-9765 U;S. Nuclear Regulatory Commission Dresden Resident Inspectors Office 6500 N. Dresden Road Morris, Illinois 60450-9766 Regional Administrator U.S. NRC, Region Ill 801 Warrenville Road Lisle, Illinois 60532-4351 Illinois Department of Nuclear Safety Office of Nuclear Facility Safety 1035 Outer Park Drive Springfield, Illinois 62704 Chairman Grundy County Board Administration Building 1320 Union Street Morris, Illinois 60450 Document Control Desk-Licensing Commonwealth Edison Company 1400 Opus Place, Suite 400
- Downers Grove, Illinois 60515 Commonwealth Edison Company Reg. Assurance Manager - Dresden 6500 N. Dresden Road Morris, Illinois 60450-9765 Mr. David Helwig Senior Vice President Commonwealth Edison Company Executive Towe rs West Ill 1400 Opus Place, Suite 900 Downers Grove, Illinois 60515 Dresden Nuclear Power Station Units 2 and 3 Mr. Gene H. Stanley PWR Vice President Commonwealth Edison Company Executive Towers West Ill 1400 Opus Place, Suite 900 Downers Grove, Illinois 60515 Mr. Christopher Crane BWR Vice President Commonwealth Edison Company Executive Towers West Ill 1400 Opus Place, Suite 900 Downers Grove, Illinois 60515 Mr. R. M. Krich Vice President - Regulatory Services Commonwealth Edison Company Executive Towers West 111 1400 Opus Place, Suite 500 Downers Grove, Illinois 60515 Ms. Pamela B. Stroebel Senior Vice President and General Counsel Commonwealth Edison Compan*y P.O. Box 767 Chicago, Illinois 60690-0767
ELECTRICAL POWER SYSTEMS B 3/4.9 BASES"
~
The initial conditions of design basis transient and accident analyses assume Engineering Safety Features (ESF) systems are OPERABLE. The A.C. and D.C. electrical power sources are designed to provide sufficient capacity, capability, redundancy, and reliability to ensure the availability of necessary power to ESF systems so that the fuel, reactor coolant system and containment design limits are not exceeded.
The A.C. and D.C. sources are designed to permit inspection and testing of all important areas and features, especially those that have a standby function. Periodic component tests are supplemented by extensive functional testing during refueling outage~ under simulated accident conditions.
3/4.9.A A.C. Sources - Operating The OPERABILITY of the A.C. electrical power sources is consistent with.the initial assumptions of the accident' analyses and is based upon meeting the design basis of the plant. This includes maintaining at least one of the onsite or offsite A.C. sources, D.C. power sources and associated distribution systems OPERABLE during accident conditions concurrent with an assumed loss of all offsite power and a worst-case single failure.
There are two sources of electrical energy available, i.e., the offsite transmission system and the onsite diesel generators. Two unit reserve auxiliary transformers are available to supply the Station class 1 E distribution system. Only when being back fed from the grid, the unit auxiliary power transformers constitute another source of offsite power to the class 1E electrical system. Physical changes to the generator links are required to place the plant in an alignment to allow backfeed. The auxiliary transformers are sized to carry 100% of the auxiliary load. If the reserve auxiliary transformer (the normal circuit) is lost, auxiliary power from the other unit can be obtained for one division through a 4160 volt bus tie (the alternate circuit). Additionally, two diesel generators are available to handle an accident.
The allowable outage time takes into account the capacity and capability of the remaining A.C. sources, reasonable time for repairs, and the low probability of a design basis accident occurring during this period. Surveillance is required to ensure a highly reliable power source and no common cause failure mode for the remaining required offsite A.C. source.
Upon failure of one diesel generator, performance of appropriate surveillance requirements ensures a highly reliable power supply by checking the availability of the required offsite circuits, and the remaining required diesel generator. The initial surveillance is required to be completed regardless of how long the diesel inoperability persists, since the intent is that all diesel generator inoperabilities must be investigated
. for common cause failures. After the initial surveillance, an additional start test is required approximately
- mid-way through the allowed outage time to demonstrate continued OPERABILITY of the available onsite power sources. The diesel generator surveillance is limited to the normal start testing, since for cases in which less than a full complement of A.C. squrces may be available, paralleling of two of the remaining A.C. sources may compromise the A.C. $Ource independence. Additionally, the action provisions ensure that continued plant operation is not allowed when a complete loss of a required safety function (i.e., certain required components) would occur upon a loss of offsite power. These certain components which are critical to aecomplishment of the required safety functions may be identified in advance and administratively controlled and/or evaluated on a case-by-case basis. With suitable DRESDEN - UNITS 2 & 3 B 3/4.9-1 Issued by letter dated February 18, 1999