ML20003H153
| ML20003H153 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 04/28/1981 |
| From: | Nichols T SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8105050232 | |
| Download: ML20003H153 (9) | |
Text
i SOUTH CAROLINA ELECTRIC a GAS COMPANY POST OFrtCE son 784 COLUMBIA, SOUTH CAROLINA 29218 T. C. NicHoLs, Jn.
ves pumic a..aaova cucun c April 28, 1981 NucLean Openanons
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{f; Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation
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U. S. Nuclear Regulatory Commission
,e Washington, D. C. 20555 k
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Subject:
Virgil C. Summer Nuclear Station Docket No. 50/395 SER Item 1.6.9 Load Sequencer
Dear Mr. Denton:
South Carolina Electric and Gas Company acting for itself and as agent for South Carolina Public Service Authority hereby commits to perform a sneak circuit analysis of the Engineered Safety Features Load Sequencer.
SCE&G will contract the services of Boeing Aerospace Company to perform the analysis and supply a report detailing the findings of the analysis. The only component analyzed will be the load sequencer itself. As previously agreed upon in a meeting with the NRC staff on April 22, 1981, the scope of this work will be limited to that outlined in the proposal supplied by Boeing to SCE&G.
A copy of that proposal is attached hereto. Target dates for the work are as follows:
(1) completion of analysis - December 31, 1981 (2) resolution of findings - first refueling Significant findings of the analysis will be resolved in a manner that is mutually acceptable to SCE&G and the NRC staff.
If you have any questions, please let us know.
Very truly yours, T. C. Nichols, Jr.
NEC:TCN:rh cc:
Page Two 8105050 M n
Mr. Har:1d R. Drnton April 28, 1981 Page Two.
cc:
V. C. Summer
'G. H.' Fischer T. C. Nichols, Jr.
C.~ A. Price' W. A. Williams, Jr.-
-D. A. Nauman R. B. Clary A. R.-Koon A. A.' Smith J. B. Knotts, Jr.
J. L. Skolds H. N. Cyrus O. S. Bradham
'B. A. Bursey ISEG NPCF PRS File 4.
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STATEMENT OF WORK HARDWARE SNEAK CIRCUIT ANALYSIS 1.0 GENERAL
.A Sneak Circuit Analysis shall be performed on the Emergency Safety Features' Loading Sequencer (ESFLS) hardware. The analysis shall be performed using the sneak analysis techniques previously developed by Boeing for NASA systems. This analysis shall identify latent electrical circuit paths and conditions that can cause an unwanted function to occur or inhibit a desired function without component failure.
Recommendations.for corrective action to eliminate these conditions shall be'provided. Also, document errors and areas of design concern discovered during the analysis shali e
be reported.
2.0 SCOPE -
The Emergency Safety Features Loading Sequencer shall be analyzed to
, identify potentially undesirabl,e circuit conditions in the system described
- .y by the drawings listed in Table 1.0.~
3.0 CHANGE ANALYSIS The analysis shall include identified changes to the data baseline received up to 30 days after contract go ahead date.
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The change analysis shall be limited to a total equal to.
10 percent of the baseline hardware design data base.
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ThBLk1.0 Schematic Title Drawing Number Engineered Safety Features 2544-1013 Loading Sequencer Schematics Virgil C. Summer Nuclear Station Unit 1 Decoding Card No. 3-4 Electrical Schematic 0423-2674 Integrated Circuit 0423-2657 Step Card No. 3-4 Electrical Schematic 0423-2679 Integrated Circuit Card No. 2 Electrical Schematic 0423-2589 Integrated Circuit Card No.1 Electrical Schematic 0423-2587 Integrated Circuit Card D Electrical Schematic 0423-2700 Component Card No. 2 Electrical Schematic 0423-2595 Clock Card Electrical Schematic 0423-2579 Lamp Driver Card Electrical Schematic 0423-2571 ESFLS Functional Logic Diagram 2544-1001 s
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4.0 TASK DESCRIPTION Specific tasks to be performed as part of this analysis contract shall co'nsist of the following:
4.1 Receive and set up files for wiring diagrams, schematics, wire lists and other input data defining electrical continuity, operation and functions of the system (s) to be' analyzed.
4.2 Convert circuit data for entry into network trees and apply existing analysis techniques to identify all continuity paths.
1 4.3 Perform a sneak circuit analysis on the resulting network trees to identify potential sneak circuit conditions, such as:
4.1.1 Sneak paths, which may allow current or energy to flow along an unexpected route.
4.3.2 Sneak timing, which may cause current or energy to flow or to inhibit a function at an unexpected time.
4.3.3 Sneak indications, which may cause an ambiguous or false display of
, operating conditions.
4.3.4 Sneak labels, which may cause incorrect stimuli to be initiated.
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5.0 REPORTS The reports shall be delivered in accordance with the attached schedule.
(See Figure 1).
5.1 Prepare Sneak Circuit Reports (SCR) on all potential sneak conditions fo"nd. Each report shall describe the sneak condition in detail. The SCR shall include a sketch of the suspect circuit, where appropriate.
Recommenda-tions for corrective action shall be given along with reference to supporting documentation. The report forms include a section for the customer to indicate the action taken to resolve the condition being reported. All reports shall be appropriately dated, titled and numbered for indexing and tracking.
5.2 Prepare Design Concern Reports (DCR). The DCR shall describe certain undesirable circuit conditions found during the analysis which do not qualify as sneak circuits.
Conditions to be reported include:
e Single failure points.
e Unriecessary circuitry or components.
e Improper implementation of redundancy.
e Improper application of components.
e Lack of transient suppression or improper suppression for inductive loads.
I 5.3 Prepare Drawing Erro,r Reports (DER) on discrepancies found in.the input data for the analysis.
Each report shall identify the discrepant document and explain the error relative to referenced supporting documentation.
5.4 Prepare and submit activity reports to describe the work accomplished during the reporting period.
The reports will include analysis progress, problems, recommendations, and results of meetings. The report shall be submitted in accordance with the attached schedule (see Figure 1).
The SCR, DCR, and DER reports generated during the reporting period shall be attached. A tabulation of all previously submitted reports (SCR, DCR, and DER) including status, shall be attached to each activity report. The status of each report shall be based on the contractor's comments stated on each report.
5.5 Prepare and submit a Final Report containing a summary of the analysis effort, including the general analysis method used, the extent of the analysis, conclusions drawn and recommendations based on the analysis.
All SCR, DCR, and DER reports written shall be included.
One report shall be prepared at the completion of the baseline analysis, and revised at the end of change analysis, if elected, to include the reports from changes.
6.0
. DATA REQUIREMENTS The analysis shall be based upon data defining details of electrical continuity and components. The information will be supplied in the form of manufacturers detail } electrical schematics) wire lists, wiring inter-connect diagrams, and component specifications _.
The data will be supplemented with available functional flow or integrated schematics, interface control documents, and design criteria specifications.
Manufacturing level electrical data and supplemental electrical data shall be furnished by South Carolina Electric & Gas to Boeing as shown in Figure 1.0.
Requests for additional data after the baseline master files have been established will be made only d
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. os 6.0 DATA REQUIREMENTS (continued) for, data absolutely essential to the con.pletion of the analysis. These additional data must be received within 30 days after request has been made.*
7.0 PERIOD OF PERFORMANCE The period of performance for the Sneak Circuit Analysis of the ESFLS System shall be 5 months after start of contract.
Reference Figure 1.0.
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- Delay in receipt of any data will result in a day for day slide in schedule and a equitable adjustment to the contract price, if any.
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