ML17326B190
| ML17326B190 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 07/29/1985 |
| From: | Varga S Office of Nuclear Reactor Regulation |
| To: | Dolan J AMERICAN ELECTRIC POWER SERVICE CORP., INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG |
| References | |
| NUDOCS 8508080688 | |
| Download: ML17326B190 (7) | |
Text
esp Ail'f July 29, 1985 Docket Nos.
50-315 and 50-316 Mr. John Dolan, Vice President Indiana and Michigan Electric Company c/o American Electric Power Service Corporation 1 Riverside Plaza
- Columbus, Ohio 43216 ON DI oc e 1
L PDR Gray File OELD BGrimes DWigginton ACRS 10 NRC PDR ORBgl Rdg HThompson EJordan JPartlow CParrish JKudrick
Dear Mr. Dolan:
By letter dated March 29, 1985, the Indiana and Michigan Electric Company
- provided, among other things, an analysis of the Donald C.
Cook Nuclear Plant substation and AEP grid system in regards to the need for backup power for the containment hydrogen ignitors.
We have completed a qualitative analysis of this information and a comparison of the Cook system to the Sequoyah system which we have approved.
Our analysis and assessment is enclosed.
On the basis of our review to date, we have determined that it is reasonable to conclude that D.
C.
Cook need not provide at this time any additional supplies for their hydrogen ignitor system.
If there are any questions on this matter, please let us know.
Sincerely,
/s/SVarga Steven A. Varga, Chief Operating Reactors Branch 81 Division of Licensing
Enclosure:
As stated cc w/enclosure:
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Mr. John Dolan Indiana and Michigan Electric Company Donald C.
Cook Nuclear Plant CC:
Mr. M. P. Alexich Vice President Nuclear Operations American Electric Power Service Corporation 1 Riverside Plaza
- Columbus, Ohio 43215 Attorney General Department of Attorney General 525 West Ottawa Street Lansing, Michigan 48913 Township Supervisor Lake Township Hall Post Office Box 818 Bridgman, Michigan 49106 W. G. Smith, Jr., Plant Manager Donald C.
Cook Nuclear Plant Post Office Box 458 Br idgman, Michigan 49106 U.S. Nuclear Regulatory Commission Resident Inspectors Office 7700 Red Arrow Highway Stevensville, Michigan 49127 Gerald Charnoff, Esquire Shaw, Pittman, Potts and Trowbridge 1800 M Street, N.W.
Washington, DC 20036 Mayor, City of Bridgeman Post Office Box 366 Bridgman, Michigan 49106 Special Assistant to the Governor Room 1 - State Capitol Lansing, Michigan 48909 Nuclear Facilities and Environmental Monitoring Section Office Division of Radiological Health Department of Public Health 3500 N. Logan Street Post Office Box 30035 Lansing, Michigan 48909 The Honorable John E. Grotberg United States House of Representatives Washington, DC 20515 Regional Administrator, Region III U.S. Nuclear Regulatory Commis'sion 799 Roosevelt Road Glen Ellyn, Illinois 60137 J. Feinstein American Electric Power Service Corporation I Riverside Plaza
- Columbus, Ohio 43216
C I
ENCLOSURE
~kd The Indiana and Michigan Electric Company (IMEC) in a letter dated March 29, 1985, provided information on the American Electric Power (AEP) grid and the Donald C.
Cook Nuclear Plant substation as justification for not providing backup power for the containment hydrogen ignitors.
Considering that IMEC has not developed a quantitative assessment of the probability of loss of all AC power at D.
C.
Cook and the ongoing work on USI A-44 on the topic of station blackout, the staff performed a qualitative design comparative assessment of the D.
C.
Cook to the Sequoyah power supply system.
This was to help determine whether further consideration should be given to,a backup power supply for the hydrogen ignition system in the event of degraded core accidents in conjunction with.a station blackout..
The Sequoyah plant already"has an installed hydrogen control system without additional power sources beyond that provided by existing emergency onsite diesels which has been approved.
II. ualitative Anal sis Recognizing the fact that an electric power system's capability to withstand disturbances resulting in total losses of AC power for the station is to a large degree a function of the system design features, a
comparison of the D. C.
Cook to the Sequoyah electric system design was made to determine on a qualitative basis how the D. C.
Cook design related to the previously accepted Sequoyah design.
Presently estimated power requirements from the hydrogen control system for both plants are as follows:
type voltage/power consumption approximate number power requirement D. C.
Cook
~Se uo ah glow plug igniter 12-14V AC/100W 120V AC/500W 70 80 7
kW 40 kw The basis for comparison of the two plants is that both D.
C.
Cook and Sequoyah have the following comparable power system capability and similar inplant design features.
D. C.
Cook no. of diesel/capacity (ea.)
4/3500 kw LOCA load requirement 2760 kW capability to intertie between units Yes Se<eSuo ah 4/4000 kw 3537 kW Yes
Com arison of Offsite Power S stem Desi ns D. C.
Cook Unit 1
Unit 2
~Sa ac ah Unit 1
Unit 2
~Switch ard I
No. of offsite lines to switchyards (switchyard voltage)
Interconnection 8(345kv) 2(765kv) 4(500kv) 10 (161kv)
Between the onsite and the switchyard (excluding step up X-formers)
Switchyard Breaker Confi uration 1 - 765 kv 1 - 345 kv 1 - 69 kv breaker and a
half scheme 2-161 kV bus transfer scheme Distribution Transformers (A)
Step up (B)
Common station service (startup) 2 62 (C)
Unit station service, or 4
unit auxiliary Both plants include a transformer which connects between units (i.e., 765/345 kW for D. C.
Cook and 500/161 kV for Sequoyah) as an offsite source.
This includes two 69/4.16 kV transformers which can be connected from one 69 kV offsite power source.
III. ~Con arison A.
B.
The D. C.
Cook switchyard design employs a breaker and a half scheme which provides a simpler and more reliable isolation capability for a certain faults (e.g.
transmission line faults, bus faults, and stuck breaker cases) with no or minimal disruption to the offsite power availability.
In case of Sequoyah, the switchyard design has a
similar capability, but requires a series of breaker operations for its transfer scheme to work and also may involve time delays.
- Thus, the 0.
C.
Cook switchyard design is less susceptible to failure as a
result of system transients.
Upon unit trip, both Sequoyah and D. C.
Cook require a transfer scheme to isolate the main generator from the offsite power system which establishes the offsite power source to supply inplant safety equipment through common station service transformers for Sequoyah and from the preferred offsite power source through transformer no.
4 for D. C. Cook.
In contrast to the offsite power supply design for Sequoyah which actually feeds from one 161 kV switchyard, the offsite power from D. C.
Cook is available from three different switchyards,
- namely, 69 kM, 345 kV, and 765 kV which undoubtedly reduces the potential for total loss of offsite power.
This, inturn, increases the availability of offsite power.
C.
Although both designs provide two diesel generators per unit, manual crossties exist in both plants, which make it possible to use one of the diesels from the other units, to supply emergency loads should both diesels be lost on one unit.
In addition, D. C.
Cook has an additional 69 kV offsite power source which can be connected manually to emergency
- buses, which is not present on Sequoyah.
IV. Conclusion By considering all the above design features such as iomediate, multiple accessib'ility to the offsite power source, instantaneous isolation capability of the breaker and a half arrangement and an additional 69 kV power source, the staff concludes that qualitatively 0.
C. Cook's AC power supply system reliability is somewhat better than that of Sequoyah.
Therefore, on the basis that Sequoyah was not required to provide additional power supplies beyond the existing emergency sources for the hydrogen ignition system, it is reasonable to conclude that 0.
C.
Cook need not provide any additional supplies for their hydrogen ignition system.