ML20077D020
| ML20077D020 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 07/18/1983 |
| From: | Jackie Cook CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| REF-GTECI-A-49, REF-GTECI-RV, TASK-A-49, TASK-OR 23860, NUDOCS 8307260320 | |
| Download: ML20077D020 (4) | |
Text
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l CORSumBIS Power James W Cook Vice President - Projects, Enginstring and Construction General officas: 1945 West Parnell Road, Jackson, MI 49201 * (517) 78& o453 July 18, 1983 Harold R Denton, Director Office of Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 MIDLAND ENERGY CENTER MIDLAND DOCKET NOS 50-329, 50-330 ANALYSIS OF NNI/ICS FAILURES CORRECTION TO BAW-1743 FILE: M1.35 SERIAL: 23860
Reference:
" Failure Mode and Effects Analysis of the Midland NNI and ICS,"
BAW-1743, Dated July 1982.
This letter forwards information recently obtained by B&W during an analyses of NNI/ICS failures for the generic Pressurized Thermal Shock Study. These analyses revealed an error in Table 6 of BAW-1743 dealing with postulated failure number 4.
This information was transmitted to Consumers Power Company in a letter dated June 22, 1983 from B&W which is enclosed as an attachment.
Table 6 of BAW-1743 presents a description of 12 NNI/ICS power supply failures and the transient response of the Midland plant to each failure. Failure 4 incorrectly states that the turbine bypass valves will fail open. Actually,:
there is no signal that will cause the turbine bypass valves to fail open for this failure. This conclusion is supported by the data presented in Table 5d of BAW-1743, The enclosed B&W letter provides a revision for the description of failure 4 in Table 6 on page 44 of BAW-1743.
Please contact us if you have any further questions.
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JWC/MFC/dlm CC RJCook, Midland Resident Inspecto JGKeppler, Administrator, NRC Region III oc0783-0513a100 Ij[
8307260320 830718 PDR ADOCK 05000329 A
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CONSUMERS POWER COMPANY Midland Units 1 and 2 Docket No 50-329, 50-330 Letter Serial 23860 Dated July 18, 1983 At the request of the Commission and pursuant to the Atomic Energy Act of 1954, and the Energy Reorganization Act of 1974, as amended and the Commission's Rules and Regulations thereunder, Consumers Power Company submits corrections to BAW-1743, " Failure Mode and Effects Analysis of the Midland NNI and ICS," dated July 1982.
CONSUMERS POWER COMPANY I
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J Cook 7 Vice President Proje s, Engineering and Construction Sworn and subscribed before me this /hday of b g/.8.
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/NotaryPubl[c Jackson County, Michigan My Commission Expires b ee % // // [
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s McDermott company 3315 Old Forest Road P.O. Bos 1260 Lynchburg, Virginia 24505-1260 (804)385-2000 June 22, 1983 CPCO: 4382
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File: 12B/T1.2 Consumers Power. Company 1945 Parnall Road Jackson, MI 49201 Attention:
Mr. L.S. Gibson Project Engineering Manager
Subject:
Consumers Power Company Midland Plant, Units 1 and 2 CORRECTION TO MW-1743
Reference:
" Failure Mode and Effects Analysis of the Midland NNI and ICS",
MW-1743,. dated July 1982.
Dear Mr. Gibson:
~~sc Recent analyses of NNI/ICS failures on the generic Pressurized Thermal Shock
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f Study has revealed an error in MW-1743. Table 6 of MW-1743 presents a description of 12 NNI/ICS power supply failures and the transient response of the Midland plant to each failure.
Failure 4, a loss of 118 volt ac power to the NNI-I system at 30% power level incorrectly states that the turbine bypass valves will fail cpan to 50% and cause'depressurization of both steam generators. For this failure, there is no sigual that will cause the turbine bypass valves to fail open; thus, there will not be any depressurization of steam generators nor overcooling of the RCS. This prediction is supported by the data presented in Table 3d of MW-1743.
~ Please revise the descriptive test of failure 4 in Table 6 displayed on page 44 of MW-1743 to read as follows:
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Page: 2 CPCO: 4382 June 22,-1963 Failure Type of Description of Transient Reactor Transient No.
Failure Tripped?
bounded by FSAR analy.
4 Fall N.11-X This is an upset transient Yes FSAR.15.2.7 118 Y ac at with mild overheating.
The 30% power reactor trip does occur dur-4 ing overheating of the RCS.
Overheating was caused by loop A&B Btu limits reducing FW flows to zero when Icop A T-hot signal failed to 570F. EFW flow was started by low SG 1evel, and the decreasing OTSG pressure caused an'in-crease in EFW flow rate the OTSGs.
Reactor tripped on high RC pressure.
The original description of the plant response. to this failure was based on a si=ulated power supply failure (and resulting -loss of input signals) to B&W's Advanced Controls Research Facility simulation of the Midland plant and ICS.
We believe that we mistakenly included the opening of the turbine bypass valves during this transient and then described the resulting transient in e, '
Table 6.
During the Pressurized Thermal Shock (PTS) Itudy, we became aware of our daving conducted that particular power supply failure incorrectly.
If any further information is needed, please call.
Respectfully,
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W.R. GRAY PROJECTE3GINEER FOR: D.F. JUDD MANAGER, CONTRACT MGMT.
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