ML20237J604
| ML20237J604 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 07/31/1987 |
| From: | Gough E, Sandra Talley, Vinquist J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| Shared Package | |
| ML20237J602 | List: |
| References | |
| GCA-87-400, NUDOCS 8708260232 | |
| Download: ML20237J604 (60) | |
Text
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1 WIRE AND CABLE PROGRAM REPORT t
RANCHO SECO NUCLEAR GENERATING STATION SACRAMENTO MUNICIPAL UTILITY DISTRICT SACRAMENTO REVISION 1 JULY 31, 1987
'. PREPARED BY:
APPROVED:
Y W
CRTS PA0 GRAM COORDINA)#R pMANAGEROFQUALITYDEPARTMENT S. R. Talley J. V. Vinquist "A
A*0'6'f' CRTS PROGRAM MANAGER MANAGER OF. NUCLEAR ENGINEERING E. J. Gough G. V. Cranston 8708260232 B70019 PDR ADOCK 05000312 P
PDR i
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Enclosure To GCA 87-400 WIRE AND CABLE PROGRAM REPORT 1.-
INTRODUCTION
- The Rancho Seco Nuclear Generating. Station at. plant turnover 'in 1975 had a cable population of about 14,000 cables. installed-mostly in ladder type cable. tray'and in steel conduit. Since 1975 about 9,000 cables have been added while a few have been deleted.
i
'In common with all large modern power plants in the United States, Rancho Seco tracks its raceway and cable data in a computerized program run-on a main frame computer. The current program has an acronym of CRTS (Cable Raceway Tracking System) and_ performs some checks and calculations as well as recording and reporting data. CRTS has been in place since July of 1980.
j The original cable population of 14,000 was installed by Cechtel Power Corporation (BPC).
BPC was both designer and constructor. Until the CRTS program was put in place in'1980, the cable and raceway was tracksJ by a BPC. Program EE-553.
This program has been used for over 20 nuclear power plants.
2.
BACKGROUND DISCUSSION 2.1' INITIATING EVENTS "Although some questions concerning CRTS completeness, missing CRTS cards-and conflicting procedures were raised by resident inspectors as early as 1983, major concerns did not arise until 1985 and 1986.
In 1985 questions arose concerning the degree of design control exercised following spurious actuations reported in LER 85-16.
In 1986 questions arose concerning the degree of control exercised during.the: installation process and the validity of "as-built" information in the CRTS data base following issuance of LER 86-10.
Employee allegations regarding overfilled cable trays and incomplete data in CRTS, added to the level lof concern.
Identified problems are listed in the CRTS Action Item List [ Attachment (1)] with appropriate references.
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Enclosure To GCA 87-400 WIRE AND CABLE PROGRAM REPORT-(Continued) 2.2 INITIAL ACTIONS '
j Initial' action taken by-SMUD was to initiate enhancement of. the CRTS program in mid-1986 and to use the. enhanced program to check for raceway overfills, violations of' separation criteria, intermixing of i
instrument cables with power and control cable, and other discrepancies as: listed in the Action Plan. Although a number of discrepancies.were " bookkeeping" problems, generated by the
- enhancement, a significant number could, potentially, have been of real concern.. Identified discrepancies.are documented in reports from the _SMUD contractor [IMPELL] to SMUD and their dispositions described in Item 2 of the CRTS Action Item List and supported.by calculations in SMUD files.
Late in 1986 a decision was made to signal; trace,a significant sample of the approximately 2400 safety cables installed from 1975 through 1986 and compare the "as-built" condition with plant docucents and the CRTS data bace to establish a level:of confidence.in the reliability of the data base. The signal tracing has found sufficient number of major defects 'in both Lot 1 (424 cables);and Lot 4 (78 cables) to require 100% inspection of each lot.
In. late June, 1987 sampling is_ complete in Lots 2, 3 and 4.
However, in July,1987 a decision was made to sample Lot 2 to the "one-defect" level, increasing the size of Lot 2 by 35 cables.
Approximately 355 cables remain to be checked, with 281 cables complete. Simply stated, the intent was to establish 95 percent confidence that the true percentage of discrepant circuits in the sampled population is no greater than 5 percent.
Forecast completion is November 1,1987.
The current status is described in Item 1 of the CRTS Action Item List [ Attachment (1)]
with further details provided in the CRTS Action Item Commentary
[ Attachment (2)].
2.3 ACTION PLAN SMUD has provided a docunent [ Appendix (2)] to the NRC which describes a five part Action Plan to consolidate the various activities of the Nuclear Engineering Department, which deal with the cable and raceway questions.
Although the scope of the plan is complete, the details and the i
individual actions require additional definition to enable a reviewer to easily determine the acceptability of the resolution of each item (i.e., question or issue raised).
The Wire and Cable Program Report is intended to replace the Action Plan and to provide additional definition and schedule information on a monthly basis.
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Enclosure To GCA 87-400 WIRE AND CABLE PROGRAM REPORT (Continued) 2.4 CRTS ACTION ITEM LIST AND COMMENTARY This report provides a listing of over fifty CRTS action items
[ Attachment (1)] with a detailed commentary on each [ Attachment (2)]. This list is intended to serve as a record of all questions raised and of all known problems.
For each item the list includes an item number, description, source, status and schedule for resolution, if appropriate.
A commentary will be provided on each item covering chronology, generic implications, causes and corrective actions as appropriate.
The July report only contains commentaries on items 1, 2, 3, 4, 5, 6, 7, 9, 10, 13, 16, 19 and 20.
To understand the significance of each item it is necessary to read the attendant commentary. The major concerns are summarized in the following section.
3.
MAJOR CONCERNS ISSUES CONCERNS Procedures The level of control exercised on cable installation.
Sampling Plan Accuracy of CRTS data on cable locations.
Data Base Completeness Omission of cables from data base.
Raceway Fill Control of cable tray fill [ weight and ampacity questions].
Design Control Mixing of instrument cables [with power &
control] in design process.
CRTS Discrepancies Control and entry of data into CRTS.
Records Control of documents of record.
Miscellaneous Problems Completeness of licensee action in resolving problems.
Root Causes Identification and correction of all identified root causes.
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Enclosure To GCA 37-400 t
WIRE AND CABLE PROGRAM REPORT (Continued)
Status of each issue is, in summary, as follows:
3.1 PROCEDURES Procedures in place during the original construction period are addressed in Item 7 of the CRTS Action Item List. Procedures in place from 1975 through 1986 will be addressed by the Incident Analysis Group [IAG]'in closing Item 4 of the CRTS Action Item List.
3.2 SAMPLING PLAN This issue is fully addressed in the commentary to Item 1 of the CRTS Action Item List.
3.3 DATA BASE COMPLETENESS The " completeness" issue of the CRTc. data, centers on the data concerning the telephone and sectrity cables. This issue, although real, has no significant safety implications. The issue also includes questions concerning Ne verification of CRTS software.
Items 10,11,12,13 and 14 of the CRTS Action Item List cover the completeness issue.
3.4 RACEWAY FILL The cable tray fill and weight questions have been reviewed.
Percentage fill and weights for all cable trays have been checked.
Although some relatively minor questions remain to be answered, no significant problems have been found. Changes are planned to USAR which will reconcile differences between the USAR and Nuclear i
Engineering Procedures and will clarify design limits. Enhancements planned to the CRTS Mtware will, when in place, automatically prevent fill and weigilt limits from being exceeded.
These questions are addressed in Items 2 [ partial] and 6 and will also be addressed in Item 26 in the August Report.
3.5 DESIGN CONTROL The design control issue is more complex than the raceway fill issue, but problems are limited to a relatively small number of instrument cables which mix with power and control cables and violate design criteri a. No evidence has been found of a programmatic failure following a review of the original 14,000 cable population. Checking of the 9000 cables added after commercial operation continues, but is not expected to change this current evaluation.
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Enclosure To GCA 87-400 WIRE AND CABLE PROGRAM REPORT (Continued)
The question of a possible generic design problem in the original 14,000 cable population is addressed in Item 5 of the CRTS Action Item List.
Other specific mix questions are addressed in Items 2
[ partial] and 9, and will also be addressed in Items 43, 44, 45, 46, 47, 48, 49 and 50, to be provided in the August monthly report.
3.6 CRTS DISCREPANCIES The large number of CRTS discrepancies, listed by the SMUD contractor
[Impell] in Task #271, is another complex question. Although the large number is initially disquieting, upon examination none have any safety significance as detailed in the commentary on CRTS Action Item 2.
One example of this is the total of 763 reported mixes of Class 1 with Class 2 or 3 cables. Almost all the 763 cables are in the original cable population which permitted mixing and none violated safety criteria. All of the 1967 Class 1 discrepancies and some Class 2/3 discrepancies have been carefully analyzed, with documentation, without finding any significant concerns. The reason for this, detailed in the commentary, is that the CRTS enhancements themselves generated the discrepancy lists which then had to be addressed.
One benefit of the CRTS discrepancy process is that the total population of 23,000 cables and related raceways has been scrutinized closely and results provide additional confidence in the lack of significant safety concerns in the cable population. This issue is addressed in Item 2 of the CRTS Action Item List.
3.7 RECORDS Record control at Rancho Seco is a simpler issue. The customary industry documents of record for installed cable and raceway are the signed installation cards. The computer tracking system is used as a convenient source of data while the verification record is the instillation card. At Rancho Seco the originals of the installation cart-for the initial 14,000 cables and raceway have not yet been founo, although facsimile record copies do exist. As discussed in the commentary to CRTS Action Item 3, we find that records for the 14,000 are apparently complete, although the clerical task of checking each cable and raceway card is not complete. Card records for the 9,000 cables and raceway sections installed after commercial operation are mostly complete. A search is being made for missing pull cards, of which 118 are safety related.
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L Enclosure
~
.To GCA 87-400 l.
WIRE AND CA8LE PROGRAM REPORT-
.(Continued) 3.8 MISCELLANE0US PROBLEMS This issue deals with the completeness of SMUD actions in identifying -
and resolving all. cables and raceway problems. Together, the CRTS Action Item List [ Attachment (1)] and CRTS Action ' Item Commentary
[ Attachment-(2)] is the vehicle which records all questions and problems.. All items with safety significance will be resolved before restart. All items with no safety significance will be resolved before the Cycle 8 outage.
All. items in the CRTS Action Item List will be reviewed for generic -
implications' before resolution. When a concern has been identified, the basic steps taken by SMUD are:
'l) Take immediate action to prevent repetition.
- 2) Identify the direct cause and take corrective action.
3)' Investigate and. identify the root cause, and if required, supplement the corrective action.
3.9. ROOT CAUSES Where applicable, root causes will be established for each item in the CRTS Action Item List. The Incident Analysis Group [IAG] will establish root causes for significant issues identified during the investigation of problems encountered in the 9,000 cables installed 1975 through 1986. This issue will be addressed in Item 15 of the CRTS Action Item List.
4.
APPENDICES 1.
Sampling Plan for Cable Raceway Tracking System Database (Impell Task 271, SMUD calculation No. 2-ZZZ-E0694, Revision 3, Dated March 17, 1987.)
2.
Rancho Seco Wire ~ and Cable Program Description and Action Plan (District Submittal Dated April 3,1987 JEW 87-478).
5.
' ATTACHMENTS 1.
CRTS Action Item List (5 pages).
2.
CRTS Action Item Commentary (48 pages).
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Enclosure To GCA 87-400 Page 1 of 48 CRTS ACTION ITEM COMMENTARY
_I_T"4 NO. 1 l
DESCRIPTION Demonstrate that the CRTS recorded cable locations match "as-built".
COMMENTARY CHRONOLOGY Employee allegations and statements as early as 1983 indicated possible deficiencies in the CRTS data with the possibility of both missing and inaccurate information. SMUD Nuclear Engineering Department [NED]
actions were pulled together into a single Action Plan in January,1987.
SMUD Incident Analysis Group [IAG] assumed responsibility for the root cause analysis of the CRTS problems and related LER's in April,1987.
In July,1986 NED authorized a contractor [Impell] to institute a review and evaluation of the CRTS program which would identify all data discrepancies, evaluate and document their significance and report to SMUD. Approximately 30,000 manhours have been expended on this effort to date and work is still continuing. Completion of this effort is Item 2 of the CRTS Action Item List.
In early December,1986, NED made a decision to signal trace a sample of safety related cables installed from 1975 through 1986.
This program is detailed in the Sample Plan [ Appendix (1)]. The plan is designed to statistically insure that the overall quality level achieves at least a 95% compliance with a 95% confidence level.
A decision was also made not to signal trace a sample of the original 14,000 cables on the basis that the original designer / constructor Bechtel Power Corporation [BPC] had exercised an acceptable level of control.
The supporting rationale for this decision is referenced in 4 tem 7.
By late June,1987 the finding of ten major defects in Lot 1 initiated a complete inspection of all 404 cables.
By late July,100 cables have been inspected; 67 completely checked and 33 inspected in the rerouted portions. Sampling of Lots 2, 3 and 4 is complete, except for the additional 35 cables required to bring the Lot 2 sample size to the "one-defect" level of 91 cables; 66 of the 91 have been traced with no major defects.
Population lot 4 consists of a group of 78 cables which were all signal traced. This was done because the signal tracing uncovered seven Appendix "R" cables which were documented as rerouted from Fire Area 36 to Fire Area 31, when this had not been done, as described in LER 87-13.
Enclosure To GCA 87-400 Page 2 of 48 ITEM NO. 1 CONTINUED These cabler were part of the group of 28 cables installed under one ECN.
This group includes the seven cables found with incorrect routes in LER 86-10. All cables in this group [28] have now been traced with the fourteen cables described having incorrectly recorded routes.
The direct and root causes of the LER 86-10 and 87-13 will be addressed by the SMUD Incident Analysis Group [IAG]. See the Item 4 commentary for the schedule.
l GENERIC IMPLICATIONS With the completion of the Sampling Plan activity, SMUD will have established a 95 percent confidence that the CRTS data base is 95 percent accurate with respect to the location of the 2389 safe shutdown / safety related cables installed from 1975 through 1986. This is viewed by SMUD as acceptable and comparable with industry norms.
The SMUD evaluation of the level of control exercised in installing the original 14,000 cables indicates a level of confidence at least equal to the 95/95 target for the 9000.
[See Item 7 of CRTS action item list].
New procedures and planned CRTS enhancements will be adequate to control the validity 01 CRTS "as-built" data.
The " completeness" issue concerning CRTS data is a separate question and is addressed in Items ll,12,13 and 14 of the CRTS Action Item List.
CAUSES The root cause is still under review.
A factor is that over the period from 1975 through 1986, eleven years, different procedures have applied.
The IAG evaluation will address the effect of differing procedures on this item [ Item 4 of the CRTS Action Item List].
From the sampling plan results the "as-built" record appears adequate.
CORRECTIVE ACTIONS The current process mandates that the installation of safety cables (Class 1 and Appendix "R") is witnessed by the QC inspector; this corrects a major deficiency in past practice. A new procedure NEAP 4127 " Cable and Raceway Tracking System" was issued in June,1987 and controls the methods by which changes are made to the CRTS data base and the issuance and processing of all installation cards. Corrective actions will be reviewed af ter the IAG root cause analysis is completed.
See the Item 4 commentary for the IAG schedule.
\\',
Enclosure To GCA 87-400 l
i Page 3 of 48 I
i ITEM NO. 2 DESCRIPTION Resolve all CRTS data base discrepancies COMMENTARY CHRONOLOGY Since July,1986, a SMUD contractor [Impell] has been performing a review and evaluation of the CRTS data for the total population of 23,000 cablu3. This review has been conducted under control of the Impell QA Program and all results have been documented and submitted to SMUD for acceptance.
Progress reports have been issued, the most current of which is Report No.
22 dated July 26, 1987._ The large number of discrepancies reported are not a cause for concern. Many are not real discrepancies but are
" bookkeeping" corrections. Still others are caused by incorrectly applying current criteria to cables which were installed to older criteria.
These " discrepancies" are therefore incorrectly reported and no discrepancy actually exists.
1 As explained in the Action Plan, SMUD will review, evaluate and disposition, with documentation, all Class 1 and Appendix "R" discrepancies prior to restart.
Class 2 and Class 3 discrepancies will be dispositioned, in the same manner, after restart but before the end of the Cycle 8 outage.
GENERIC IMPLICATIONS Each discrepancy has to be evaluated separately.
The evaluations may be sunnarized as follows:
(Note that the Action Plan totals have, in some cases, changed as 1
indicated.)
Class 1, Item 1.0 - Intermixing of Class 1/2/3 Cables (Total 763)
None of the 763 discrepancies are valid.
The total Dreaks down as follows:
669 Are part of the 14,000 original cables and are correctly installed. This is because the original criteria allowed mixing, provided that no Class 2/3 cables " bridged" redundant Class 1 separation groups.
82 Are either deleted or are routed in "special" raceways so that no mixing occurs.
12 Were installed post-1975 but under the original plant criteria.
All may be grouped with the 669.
Enclosure To GCA 87-400 4
1 Page 4 of 48
.)
ITD4 NO. 2 CONTINUED Class 1 Item 2.0 - Overfilled Trays (Power and Control) Total 38 The 38 cable trays were reviewed to determine their fill at the time of commercial operation and their current fill with the results given below.
The 38 were checked for both ampacity derating and also for weight.
EE-553 CRTS EE-553 CRTS 10/14/75 3/9/87 10/14/75 3/9/87 Tray
% Fill
% Fill Tray
% Fill
% Fill L43AZ3 44 42 M41F1 36 40 L44AK1 45 49 M41 G1 34 38 L44AU1 41 42 M41 H4 36 41
)
L44BF1 36 38 M41M3 42 44 l
L44BM2 17 40 M41P1 34 38
)
L44BN2 34 43 M41X1 39 40 i
L44BY3 47 49 M41 Y1 39 40 L44CF1 45 51 M41Z1 31 40 L44P1 39 39 M43V10 47 40 L44P2 39 40 M43V11 34 37 L44V36 49 47 M44AU1 39 38 M39BA7 40 42 M44AY1 34 39 M40AM2 36 42 M44AY4 49 53 M40AQ2 37 42 M44V10 61 59
{
M41 AAl 30 35 M44Vil 36 43
)
M41 AD1 34 39 M44V70 38 41 i
M41AEl 32 36 M4581 48 45 J
M41 AFl 32 36 M45V10 38 41 M41BD1 35 35 M45V8 48 42 An issue raised by the Resident NRC Inspector concerned the documentation of ampacity and weight checks. The specific question was "Did SMUD 3
perform 10CFR50.59 reviews of overfilled trays?" The review process for the original 14,000 cables and the later 9,000 added cables was as follows:
Original Installation Power and control cable trays filled in excess of 40% were checked to verify that the cable loading was not in excess of 50 lbs/ linear foot.
Instrumentation cable trays filled in excess of 60% were checked to verify that the cable loading was not in excess of 50 lbs/ linear foot.
Instrumentation cable tray fill between 40% and 60% was accepted based upon a generic calculation.
In addition, ampacity checks were made on all power and control cable trays filled in excess of 40%.
No documentation of the design checking has been found in Bechtel or SMUD files.
Retention of such documentation was not a common practice.
As detailed later in this commentary, all fills and weights have now been checked and documented.
___________________A
Enclosure To GCA 87-400 1
f Page 5 of 48 i
ITEM NO. 2 CONTINUED Cables Installed After Commercial Operation Power and CL :, col cable trays filled in excess of 40% were dispositioned as described for the original installation, the cable loading was verified to be less than 50 lbs/ linear foot and the ampacity was checked.
The results were not documented by calculation, and no formal reviews were performed to verify that weight limits were met.
Instrumentation cable trays filled in excess of 50% were checked to verify that the cable loading was not in excess of 50 lbs/ linear foot.
Instrumentation cable tray fill between 40% and 50% was accepted based upon a generic calculation.
The results of the instrumentation cable tray weight checks were also not documented and no formal 50.59 reviews were performed.
Results At this time, July 1,1987, all cable trays and conduits have been reviewed for fill and for weight problems.
Percent fill is a feature of the CRTS program. Weight calculations were performed by a separate program run on a-PC and performed on data " dumped" from the main computer. Results are as follows.
Instrument Tray Fills The USAR limit is 40% versus the Nuclear Engineering design criteria which has a 50% fill limit for instrument cable trays. All trays have been checked for weight, regardless of fill level.
No trays were found to exced the USAR limit of 50 lbs/ linear foot.
Visual checks are being performed for " heaped" or " mounded" conditions indicating possible problems during a design basis earthquake. At this time no significant problems have been found.
The USAR fill limit will be changed to 50%.
Power and Control Tray Fills The USAR limit is 40%.
All trays have been checked for weight, regardless of fill level.
One Class 2 cable tray is overweight by 1.16 lbs and cables are being removed to delete the excess.
No other trays have been found with "real" fills in excess of 50 lbs/ linear foot. A few " false" fills have been found which are in the process of correction.
" False" fills occur when long tray sections include all cables in the weight calculations and exceed 50 lbs/ linear foot, even if some of the cables only run a short distance in the raceway section, whereas the weight borne between supports does not exceed 50 lbs/ linear foot. Documentation is provided by Impell under Task 334. Ampacity checks have been made on all power and control cable trays with fills in excess of 40%.
No ampacity problems have been found.
Enclosure i
To GCA 87-400 l
Page 6 of 48 ITEM NO. 2 CONTINUED Summary of Overfilled Tray Review No significant problems have been found to date.
Final checks are required to check special conditions to verify that their impact is minimal :
Weight contribution from telephone / security cables.
Weight contributions from fire wrapping and cable tray covers.
Causes of Overfilled Trays No significant problems have been found and there appears to have been a reasonable degree of conservatism in the original design.
Nevertheless, the lack of documented reviews in the period 1976 to 1986 is an omission in the design process which should not have occurred.
Enhancements planned for the CRTS software will, in the future, automatically block cable additions which exceed fill and weight limitations.
Class 1 Item 3.0 - Overfilled Conduits (Power / Control) (Total is 108 Was 107) 1 All 108 are either incorrectly recorded fills, because the "as-built" conduit is larger than recorded or are acceptable for other reasons (very short length). Quite obviously conduits cannot easily be overfilled, unlike trays, and all 108 have documented dispositions indicating a complete lack of either fill or ampacity problems.
Class 1, Item 4.0 - Overfilled Conduits (Instruments) (Total is 14; Was 13) l All 14 are dispositioned as false fills or similar.
No ampacity problems exist with instrument cables.
j Class 1, Item 5.0 - Raceway Connections (Total is 293; Was 200)
The CRTS program established " linkages" or " nodes" to check that connecting raceways in cable vias did, in fact, connect. When nodes were missed by designers making the drawing changes, each missed node generated a discrepancy report for each cable using the via. All missing nodes have been checked and the " bookkeeping" errors corrected.
i Class 1, Item 6.0 - Duplicated Numbers (Total is 2; Was 35)
These are two " bookkeeping" errors both of which have been dispositioned as having no significance.
t 1
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Enclosure To GCA 87-400' Attachment 2-
-Page 7 of 48 ITEM NO. 2 CONTINUED-Class 1. Item 7.0 - Document Discrepancies (Total is 555; Was 551)
The 555 are a miscellany of minor data discrepancies dealing with entries covering equipment numbers, raceway numbers, cable codes, cable data (conductor size / number) and others. All have been checked and the data
. corrected.as needed.
No data questions remain open.
y Class 1 Item 8.0 - Tagging / Identification Discrepancy (Total is 0; Was 7)
The original seven items are now reported in the Item 5.0 totals.
Class 1. Item 9.0 - Missing / Unsigned Construction Cards (Total is 180; Was l._
53)
L-The 180 cards all exist but are missing signatures.
Three NCR's'have been issued covering all 180.
Dispositioning will require verification of terminations or cable / conduit locations, whichever is appropriate.
l Termination'and cable verifications, about 60, are complete. Conduit data i
will be verified prior to restart.
The following Non-Class 1 discrepancies have all been dispositioned without finding any safety problems.
Non-Class 1, Item 1.0 - Intermixing of Power / Control / Instrument Cables (Total is 400; Was 125)
The USAR wording requires separation of instrument cables from power and control cables for RPS and ESFAS.
USAR does not clearly address mixing for other systems.
USAR also does not address or define what constitutes instrument, control and power cables.
SMUD Nuclear Engineering Procedures (NEP's, Criteria and Guides) also did not clearly define instrument, control and power cables.
However, various types of signals (analog, digital) were discussed and digital signal cables permitted to mix with control cables.
The NEP's have been revised to define the separation required between instrument and power and/or control cables and to define the instrument circuits requiring separation. Details are given in the commentary in CRTS Action Item 9.
Enclosure To GCA 87-400 Page 8 of 48 ITEM NO. 2 CONTINUED The 400 reported Non-Class 1 mixes have been dispositioned as follows:
367
. Accepted as meeting NEP's.
16 To be rerouted.
17 Which require drawing changes to clarify service level.
400 Total The original design process used twisted shielded pair (TSP) or coax /triax cables for all circuits considered as instrumentation.
This has led to some confusion since no cable service levels are established in CRTS. A future CRTS' enhancement will identify service levels for all cables.
Non-Class 1, Item 2.0 - Overfilled Trays (Power and Control) (Total is 153 Was 131 )
All trays have been checked for weight.
Only one tray exceeded the 50 lbs/ linear foot USAR limit. Ampacity checks have been made on all cable trays with fills over 40%.
No ampacity problems have been found.
Non-Class 1, Item 3.0 - Overfilled Trays (Instrument) (Total is 18 Was 19)
All trays have been checked for weight.
None exceed the 50 lbs/ linear 1
foot USAR limit.
Non-Class 1, Item 4.0 - Overfilled Conduit (Power and Control) (Total is 644 Was 639)
All 644 are either incorrectly recorded, because the "as-built" conduit is larger than recorded in CRTS or are acceptable for other reasons. No ampacity problems exist.
i 1
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Enclosure To GCA 87-400 Page 9 of 48 r
ITEM NO. 2 CONTINUED Resolution of Minor CRTS Data Discrepancies A number of minor Non-Class 1 data discrepancies exist.
These are summarized below.
None have any safety significance. These data discrepancies will be resolved after restart but not later than the Cycle 8 scheduled outage.
Non-Class 1 1 ~. 0 Overfilled Conduits (Instrument / Telephone)-
1 51 2.0 Raceway Connections 1390 3.0 Duplicated Numbers 33 4.0 Document Discrepancy 1594 5.0 Tagging / Identification Discrepancy 130 6.0 Missing / Unsigned Construction Cards 92 Sub Total 3390 Security 7.0 Raceway Connections 177 8.0 Duplicated Numbers 29 9.0 Documentation Discrepancy 276 10.0 Tagging / Identification Discrepancy 4
11.0 Missing / Unsigned Construction Cards 88 Total 3964 Causes of Discrepancies The enhancement of the CRTS software generated the list of discrepancies.
The discrepancies were caused by the data base conversion and errors entered into tne data base in the 1980 to 1982 time frame.
The root cause of the CRTS problems will be determined by the IAG.
Both the design and installation processes will have to be examined to find out
)
how data errors came to exist in such large numbers. The level of control exercised is addressed in Item 4 of the CRTS Action Item List.
1 CORRECTIVE ACTIONS Major (safety related) discrepancies will be reviewed and dispositioned, with documentation, prior to restart. Minor (non-safety related) 1 discrepancies will be reviewed and dispositioned, with documentation, l
prior to the end of the cycle 8 outage.
Disposition of each discrepancy will include verification that plant design documents, the CRTS Data Base and the "as-built" plant configuration are all in agreement.
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Enclosure To GCA 87-400 Page 10 of 48 1
ITEM NO. 3 DESCRIPTION Define SMUD document of record controlling cable location.
COMMENTARY CHRONOLOGY-In a January 7,1987 meeting, the Region V Electrical Inspector [Mr. Andy Hon] asked where cable pull cards are now kept and what will be done with cable pull cards in the future.
To answer the question concerning SMUD future actions required defining the SMUD documert of iecord for cable locations. Answers to the two original questions and the additional definitions are as follows:
1.
NRC Question:
Where are cable pull cards now kept [ January, 1987]?
District Response: The cable pull cards together with equipment and raceway installation cards were kept in either locked metal card files in an office area of the "Bechtel Building", which is a temporary on-site construction office or in boxes in trailers used as temporary offices.
2.
NRC Question:
What will be done with cable pull cards in the future [After January,1987]?
District Response:
The cable and raceway installation cards are now being kept in a " vault" in the "Bechtel Building". The record documents are a mixture of original carcs and facsimiles when the originals cannot be found.
The vault is a secure, locked room with cement walls and a Halon Fire Protection System.
At this time, records are being checked to see how many cards are missing.
When original cards are not found, facsimiles from the construction records will be substituted to create a complete record.
A duplicate record is being created on microfilm. During March and April 1987, about 4500 cards were microfilmed and stored on the second floor of the T&R Building.
This process will continue until a complete duplicate record is established.
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Enclosure To GCA 87-400 l
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Page 11 of 48 ITEM NO. 3 CONTINUED Additional Information 1.
INSTALLATION VERIFICATION RECORDS FOR INSTALLED CABLE AND RACEWAY The Installation Verification Records for installed cable and raceway are the " pull cards" and " raceway installation" cards respectively.
As of July 1,1987,118 Class 1 cable pull cards (originals or facsimiles) have not yet been located. Full details of all missing cards (all types) are given in Section 4.
2.
ENGINEERING RECORDS FOR DESIGNED CABLE AND RACEWAY These records are the input documents to the CRTS program.
These are designated as " forms" and are engineering drawings by SMUD definition.
CRTS input drawings / forms are as follows:
E-1008 Raceway Input Document E-1010 Scheme Cable Input Document E-1026 Raceway Code Input Document E-1027 Cable Code Input Document E-1028 Electrical Equipment Input Document Originally new forms were issued for changes. As of June 15,1987, all new cable and raceway input documents have been handled as Drawing Change Notices.
Originals of input documents are i
being marked to show changes instead of issuing new forms.
3.
CRTS PROGRAM AND DATA BASE The function of the CRTS program and data base is two fold:
a.
An engineering design tool which is used by the design group to perform design checks and calculations.
Currently the CRTS program checks for:
Raceway continuity Percentage fill Mixing of redundant separation channels Verifies raceway service levels for compatibility The CRTS is being enhanced to perform:
Weight calculations Checks on mixing of instrument cables with power and control cables
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Enclosure To GCA 87-400 Page 12 of 48 ITEM NO.=3 CONTINUED b.
A convenient data source which is used for engineering design information. - Typical uses of the CRTS generated information are:
Identification of cable routes Calculation of totals of combustible materials (Btu totals)
Weight calculations for cable tray sections GENERIC IMPLICATIONS Plant cables = provide many diverse functions.
The cables of safety systems provide both power supply and control functions, as well as important indications to operators.
The control and separation of redundant safety groups of. cables and of all cables' required for safe shutdown are important safety factors.
The existence of reliable and accurate records; concerning the location of the cables is essential to' plant safety.
With the completion of the Action Plan, SMUD will have established a-record file of installation ' cards (originals and facsimiles) and-a duplicate microfilm record.
SMUD.will also have-confirmed that the CRTS data: base is accurate to an acceptable confidence level.
With adequate maintenance of both records and CRTS data, the necessary level-of control will exist.
-CAUSES Difficulties in tracing records indicate a need for greater management interest in record storage and an increased awareness on the part of SMUD employees of the importance of records.
CORRECTIVE ACTIONS Replacement Cards: Replacement cards will be generated, by CRTS, for all missing cards. Tne cards will be checked against the design documents.
Checked cards' will be marked " Replacement Card" and the checker will sign and date the card.
Current Process: A new procedure (NEAP 4127) was issued in June,1987.
This procedure is considered adequate to ensure that all cards are returned to -CRTS.
4.
TOTAL NUMBERS OF MISSING CARDS The following are details of all missing cards as of July 1,1987:
Enclosure To GCA 87-400 Page 13 of' 48 ITEM NO. 3 CONTINUED Cable Raceway Tracking System (CRTS)
ANALYSIS OF 1,800 MISSING CABLE CONSTRUCTION CARDS July 3, 1987 Nuclear (I)
Nuclear (2)
Both(3)
(4)
Operation Engineering Depts.
Pre-ECN Total Missing Cards 797 - 44%
806 - 45%
61 - 3%
136 - 8%
' Pull' Cards 142 - 8%
177 - 11%
27 - 1%
2 - 0.1%
'From' Termination Cards 308 - 17%
146 - 8%
17 - 1%
3 - 0.2%
'To' Termination Cards 296 - 16%
193 - 10%
17 - 1%
3 - 0.2%
' Delete' Cards 51 - 3%
290 - 16%
0 - 0%
128 - 7%
Total Cables in Data Base (CRTS Revision Level 1504) 23,218 Total Cables Having Missing Cards 1,072 Fraction of Cables Having Missing Cards 4.62%
Total Missing ' Pull' Cards 348 -
19%
- Total Missing ' Termination' Cards 983 - 55%
Total Missing ' Delete' Cards 469 - 26%
Total Missing Cable Cards 1,800 - 100%
(1) Nuclear Operations [NO] initiated ECN.
(2) Nuclear Engineering [NE] initiated ECN.
(3) N0/NE jointly initiated ECN.
(4) Proposed cables entered 1976-1980, no ECN.
Missing Class 1 ' Pull' Cards 118 (7%)
Enclosure To GCA 87-400 Page 14 of 48 ITEM NO. 4 DESCRIPTION Document the level of control exercised by SMUD in installing cable 1975-86 CHRONOLOGY -
Questions concerning the completeness of CRTS data, missing installation cards and conflicting procedures have been raised starting in 1983.
The existence in 1978 of Quality Control Instruction QCI 107, which required the destruction of installation cards, raised questions concerning records.
Employee allegations and statements to the SMUD Ombudsman also tended to indicate some possible problems in controlling the installation process.
LER 86-10 identified 7 Appendix "R" cables which should have been relocated but were not. Additional analysis of the cable installation process is required to determine if root causes can be identified and lessons learned from them.
The SMUD Incident Analysis Group [IAG] has started their review of this item [with Action Item 54] and has established a schedule based on availability of information from the Nuclear Engineering Department.
i Forecast dates of other IAG investigations are as follows:
CRTS ACTION DESCRIPTION FORECAST ITEM 24 Determination of cause of redundant Aug, '87 cabling in same fire area (LER 86-10).
25 Determination of cause of redundant Aug, '87 instrument cables routed through same fire area (LER 87-13).
54 Description of the installation Sept, '87 procedures and practices used at Rancho Seco for the 9,000 cables I.
added after commercial operation l
(1975-86).
l 55 Description of the events and LER 85-16 Aug, '87 circumstances leading to the LER 86-10 Aug, '87 misrouting of cable described in LER 87-13 Aug, '87 LER's LER 87-26 Sept, '87 56 Description of the events and Aug, '87 circumstances leading to the discrepancies discovered between the "as built" cable routes and the 1
routes recorded in CRTS.
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Enclosure To GCA 87-400
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Page 15 of 48 ITEM NO. 5 DESCRIPTION Demonstrate that no Bechtel generic design problem existed.
COMMENTARY CHRONOLOGY With the discovery of a misrouted RCS pressure transmitter instrument cable as being a possible cause of the August and December 1985 spurious closures of the Decay Heat System (DHS) valve HV-20002 (LER 85-16), and the further identification that the misrouting of the instrument circuit occurred during the original design of the plant, investigation of the original cable population was begun for any evidence of a generic design problem.
GENERIC IMPLICATIONS The original Rancho Seco cable population consisted of nearly 14,000 cables, routed in 13,000 raceways. The original Rancho Seco EE-553 circuit and raceway schedules were reviewed for any evidence of a generic design problem in the original cable population. Since the present CRTS data base has been reviewed for raceway fills and weights, channel separation and channel " bridging", and would have identified any such problems in the original cable population, only intermixing of power, control and instrumentation cables was examined in the original cable population.
l 4
Enclosure To GCA 87-400 Page 16 of 48 ITEM N0. 5 CONTINUED The EE-553 raceway schedules were reviewed for any indication of a generic problem concerning power / control / instrumentation intermixing. Approximately 3200 pages were manually reviewed, representing approximately 13,000 raceways. Approximately 10 cases of Class 1 intennixing were identified and approximately 60 cases of Non-Class 1 intermix 1ng were identified (Table 1),
with no evidence of a generic intermixing problem.
It should be noted that of the 10 Class I cable intermixes, that 8 no longer exist in the plant. The remaining 2 cables provide tachometer indication signals to local panels of the Bruce GM Diesels, Reference Drawing E344 Sheets 1, 4 and 5, and have no safety features actuation function.
CAUSFS Both the FSAR and USAR require separate cable tray, conduit and penetration systems for 600-volt power and control cables, and for instrumentation cables. The cable scheme numbering system used at Rancho Seco requires a 1 in the first location of the cable scheme number to designate Rancho Seco Unit 1.
A digit in the second location of the cable scheme number designates a power cable, a letter in the second location of the cable scheme number
. designates either a control cable or an instrumentation cable. Without a method to differentiate the scheme cable number of a control cable from that of an instrumentation cable, intermixing may have occurred.
CORRECTIVE ACTION Upon the consolidation of SMUD efforts to resolve Rancho Seco wire and cable problems (Action Plan, JEW-478 April 3,1987), Bechtel was asked to review the 1975 cable and raceway schedules for any evidence of a widespread problem concerning the intermixing of power, control and instrumentation cables. The intermixing of instrumentation cables in power and control raceways was identified by examining the 1975 EE-553 raceway schedules for any shielded cables in power and control raceways.
In order to identify the power and control cables intermixed with instrumentation cables in instrumentation i
raceways, the 1975 EE-553 raceway schedule was examined for non-shielded cables in instrumentation raceways. The results are given in Table 1 and will be dispositioned by the end of August,1987.
In. order to prevent any further occurrences of power, control and instrumentation intermixing, SMUD has directed by memo that an additional column be added to the "1010" drawings and DCN's to indicate the service level of the cable being added.
For each added cable, the new column will indicate either P. C, or I for power, control or instrumentation service. Providing
. the physical designer with the necessary information to properly route newly added cable. Additional service level designators are under consideration and include T [ Telephone], S [ Security] and IE [ Instrumentation - Exempt - may mix with P and/or C cables].
L Enclosure To GCA 87-400 l
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Page 17 of 48 ITEM NO. 5 i
CONTINUED Table 1 i
l Original Cable Population Power / Control / Instrumentation Intemixing
-)
i Class 1 Intemixing Power Cable in Instrumentation Raceway None I
Control Cable in Instrumentation Raceway 1M1A131D
- IM1A131E
- 1MIB139D
- IM1B139E
- Instrumentation Cable in Power and Control Raceway 1G1Q886CS 1GlQ886DS 1RIC260AA
- 1RIC260AB
- 1RIC260BA *'
1RIC260BB
- Non-Class 1 Intermixing Power Cable in Instrumentation Raceway 112E07A 112GSIGC
- 112SDPS6A
- 112E11D 112GS1GF
- 112SDPS1B
- 112E11E 112GSIGG
- 112SDPS2B
- 112E09CN 112J11EA
- 112SDPS3B
- 112E09CO 112SDPSIA
- 112SDPS4B
- 112E09DI
- 112SDPS2A
- 112SDPS5B
- 112F15Z 112SDPS3A
- 112SDPS6B
- 112GSIGA
- 112SDPS4A
- 1120230B 112GSIGB
- 112SDPSSA
- 113C109A
- Cable deleted, no longer installed in plant
Enclosure To GCA 87-400 Page 18 of 48 ITEM NO. 5 CONTINUED Table 1 (cont.)
Control Cable in Instrumentation Raceway 1A3A265D3 112B360CA
-1M20327I 1A3B470A1 II2B360T IM2D202B
- 1A3B470A2 II2B365CA 1M202241 1A38470A4 II2B365X IM2D228D 1A3P200B2 II2G996D IM2D229D 1A3P20086
.112N150LF IM2I2038
- 1A3X5208 1A3X520H-Instrumentation Cable in Power and Control Raceway
'112G201 II2R301B 1R21460B II2G202 II2R520AB IR2PBTPA
'112G203 II2R520AF 1R2T250A II2G204
'112R520AJ II2G417 112R532AB
- Cable deleted, no longer installed in plant
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Enclosure To GCA 87-400 Page 19 of 48 ITEM N0. 6 DESCRIPTION Resolve overfill / overweight questions; including USAR and 50.59.
COMMENTARY l
q CHRONOLOGY l
In February,1986 ODR 86-125 was prepared as a result of an investigation following allegations of raceway overfilling.
The ODR examined instrument j
cable tray overfilling, because instrument trays are filled to a higher level than power and control trays, and determined that for the cable tray with the highest fill, that the cable loading did not exceed 50 lbm/ft.
In addition, it was verified that the actual cable tray loading was used in the fire hazard analysis and also that the cable tray heat derating was acceptable with respect to the cable ampacity.
As a result of the above i
I investigation, 38 Class 1 overfilled trays and 150 Non-Class 1 overfilled trays were identified and subsequently reviewed for overweight and ampacity concerns, with only one Class 2 cable tray overweight.
ODR 87-204 was initiated in February,1987, as a result of concerns that cable trays with fills less than 40%, might in certain unique circumstances, exceed the cable loading of 50 lbm/f t. LER 87-24 was also initiated to determine the deportability of the identified problem.
GENERIC IMPLICATIONS l
The Rancho Seco USAR limits the fill of redundant cable trays to 40%, so as not to exceed the cable loading of 50 lbm/ft used in the cable tray support design.
Cable trays do exist whose fill exceeds 40% and were dispositioned during the original design process.
Power and control cable trays filled in excess of 40% were checked to verify that the cable loading was not in excess of 50 lbm/f t.
In addition, an ampacity check was performed.
Instrumentation cable trays filled in excess of 60% were checked to verify that the cable loading was not in excess of 50 lbm/ft.
Cable tray fill between 40% and 60% was accepted based upon a generic calculation. Although the above calculations were performed during the original design process, the calculations have not been found.
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Enclosure To GCA 87-400 Attachment 2-i Page 20 of 48 j
ITEM NO. 6
'l CONTINUED l
Power and control cable trays filled in excess of 40% after commercial operation were dispositioned as described for the original installation.
For instrumentation cable trays filled in excess of 50%, the cable loading was verified not' to exceed 50 lbm/ft. the results of the weight checks performed after commercial operation were.not documented and no formal 50.59. reviews were performed. As of May,1987 all cable trays have been reviewed for fill.and weight problems, with only one Class 2 power and control -cable tray overweight.
i
- The USAR limit is 40% for power and control tray fills. All. trays have been checked lfor weight (regardless of fill level).
Only one tray has-been found with a "real" fill in excess of'50 lbs/ linear foot.
" False" fills have been found where a long tray sections include all cables in'the weight calculations (and exceed 50 lbs), whereas the weight borne between supports does not exceed 50 lbs. Ampacity checks have been made on all power'and control cable trays with fills in excess of 40%. No ampacity problems-have been found.
1 I
'The USAR limit is 40%' for instrument tray fills and is at variance with.
the Nuclear. Engineering criteria which has ~a' 50% fill limit for instrument cable trays. All trays have been checked for weight (regardless of fill v
level). No instrumentation trays were found to exceed the USAR limit of 50 lbs/ linear foot. Visual checks are being performed for " heaped" or
" mounded" conditions indicating possible problems during a design basis earthquake. ' At this time no significant problems have been found. The 1
USAR limit will be changed to 50%.
l In summary, no significant problems have been found to date. Final checks on weight contributions from telephone / security cables and weight j
contributions from fire wrapping are required to verify that their impact is minimal.
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Enclosure To GCA 87-400 Page 21 of 48 ITEM NO. 6 CONTINUED CAUSES As evidenced by the discovery of only one significant problem concerning overfilled cable trays, the original 40% fill limit was a very conservative requirement in the original plant design. However, the absence of documented 50.59 reviews for those cable trays whose fill was exceeded post-commercial operation is a cause for concern.
i CORRECTIVE ACTION i
i Immediate corrective action has been to review all cable tray weights regardless of fill level [ See commentary on CRTS Action Item 2].
Additionally, for new design work [added cables], all power and control trays which exceed 40% fill are checked for weight and ampacity; all instrument trays whose fill exceeds 50% fill are checked for weight.
In addition, the 50.59 review concern will be resolved under Nuclear Engineering Action Item Memo No. 2278, with a forecast date of September 1, 1987.
I S
Enclosure To GCA 87-400 Page 22 of 48 ITEM NO. 7 DESCRIPTIQJ Justification for not sampling the original cable population.
COMMENTARY CHRONOLOGY As a result of employee allegations as far back as 1983, and with the June 1986 identification of seven misrouted appendix "R" cables, a decision was made in December 1986 to signal trace a sample of safety related cables, installed af ter commercial operation in 1975.
The original cable population of 14,000 cables was excluded from the sampling plan, because the design, installation and inspection of the original cable population by Bechtel Power Corporation, Rancho Seco A & E and Constructor was governed by a quality program sufficient to control the physical design and installation of the original cable population.
SUMMARY
Justification for excluding the original cable population was presented by SMUD, during the June,1987 NRC inspection visit, in the form of a report.
The report, titled " Justification For Not Sampling The Original Rancho Seco Cable Population," was formally transmitted by GCA 87-338, dated July 24, 1987.
The report demonstrates that Bechtel had in place and used a rigorous quality program sufficient to control the physical design of the original cable population.
In contrast to those cables installed af ter commercial operation, the original cable population was installed while the plant was in a construction mode, under a uniformly consistent set of rules and procedures.
The procedures did not vary during the design, installation and inspection of the original cable population and it will be shown that these procedures were rigorously followed by a relatively stable and well trained workforce. The justification for not sampling the original cable population will be included as an appendix to this commentary in the August submittal of the Wire and Cable Program Report.
Enclosure i
f To GCA 87-400 Page 23 of 48 l-l ITEM NO. 9 Description-
. Resolve Power / Control / Instrument Cable Mixing Concerns
~ Commentary Chronology-LER 85-16 Rev. 0 was the first documented evidence that instrument cables -
had been mixed with power and/or control cables at Rancho Seco. Since this discovery, additional " mixing" has been found and details are provided in the commentaries to CRTS Action Items 2 [ partial] and 5, and will also be addressed in Items 43, 44, 45, 46, 47, 48, 49 and 50, to be provided in the August monthly report.
Generic Implications 4
The concern is. the avoidance of unacceptable noise levels,- caused by cross-coupling'between adjacent conductors, in instrument circuits. The level of noise is a concern for analog circuits and'some ' digital ci rcuits. No concern attaches to' cable insulation levels since all power, control and instrument cables have 600 Yolt insulation ratings and additional protection in the form of a protective outer' jacket.
The ability of a circuit to tolerate noise is a function of the equipment connected to it. The type of equipment. and the provision of noise
" filtering " components both play a part.
The original design approach at Rancho Seco was typical of plants of similar vintage. The raceway design for the original 14,000 cables provided two service levels for 600 volt class cables [NEPM 5103 Section 5.4.5.1] (1.b) 480 Volt (and below) power, DC and control and (l.c) instrumentation. No explicit definitions existed for either power, control or instrument circuits. Service levels were indicated for raceways as follows:
For Class 1 power and control raceway, the raceway designator begins with either the letter L, M P or W for Channel A, B, C, or D, i
respectively.
For Non-Class 1 power and control raceway, the raceway designator begins with the numeral 7.
For Class 1 instrumentation raceway, the raceway designator begins with either the letter A, B, C or D for Channel A, B, C or D, respectively. For Non-Class 1 instrumentation raceway, the raceway designator begins with the letter X.
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I Enclosure To GCA 87-400
,o i
Page 24 of 48 ITEM NO. 9 CONTINUED Conduit is differentiated from cable tray by having all digits af ter the first letter or number; cable tray is identified by having both letters and numbers after the first letter or number raceway. designator.
For example:
L27AFI - Channel A Power and Control Cable Tray M47223 - Channel B Power and Control Conduit 727BAl - Non-Class 1 Power and Control Cable Tray 732007 - Non-Class 1 Power and Control Conduit A32AB2 - Channel A Instrumentation Cable Tray D44301 - Channel D Instrumentation Conduit X44AD3 - Non-Class 1 Instrumentation Cable Tray X56032 - Non-Class 1 Instrumentation Conduit Scheme cable numbers did not indicate the service level [P, C or I] for cables; however, a standard practice was used which identified all 600 volt shielded cables [ twisted shielded pairs, coax, triax etc) as instrument cables. This practice allowed latitude to the designers in classifying circuits as " instrument" when the circuits were shielded.
For example with this approach low amperage (0.5 amp) 120 Volt power supplies could be installed using shielded, twisted pair cable and run with signal cables. When a field component (e.g. flow transmitter) was provided with only one entry [ conduit hub] this was an obvious practical approach, meeting the equipment suppliers intent.
For safety circuits an unacceptable noise level is a plant safety issue. For this reason the USAR wording requires separation of instrument cable from power and control cables for RPS and SFAS while not explicitly addressing other systems.
In practice, the design intent has always been to maintain the same separation for all systems. Design Guides written in 1984 and later have attempted to provide more explicit direction with the result that the design intent for the original 14,000 cables and cables installed later has become blurred.
Causes The direct cause for each identified problem [CRTS Action Items 2 (pa rtial ), 5, 43, 44, 45, 46, 47, 48, 49 and 50 will be addressed in each individual commentary. Not all identified problems are, upon examination, real problems. A major cause of both real and incorrectly identified " mix" problems is an inadequate definition of design intent in both USAR and design documents.
A description of the events and circumstances leading to the discrepancies identified in LER 87-26 is in preparation by IAG [ Incident Analgis Group] and will be included in the September issue of the repo
Enclosure To GCA 87-400 Page 25 of 48
)
ITEM NO. 9 CONTINUED Corrective Actions - Physical Rework 1
The physical reworking of cables because of mix problems 's identified in the following:
L EJl_85-16. Seven cables required relocation. NCR's S-S263 and S-5968 were issued. ECN's R-0459 and R-1295 detail the work.
M LER 87-26. Twenty-eight cables required relocation.
NCR's S-C661, 5-65d2, 5-6563, S-6564, S-5565 and S-6566 were issued. ECN R i785 and ECN R-1786 detail.the work ECN R-1785 will be issued in Agust,1987.
ECN R-1786 was issued on June 29, 1987 and the forecast constr;ction comp?etion ~date is, August; 1987.
CRTS Databy e Discrepancies [CRTS Action Item 2]
Sixteen routing errors requiring relocation were identf fdea!by Impell as documented by CPR's CPR-0611, 610, 885, 638, 640, 622, 642 and CON's CON-584 and 742 contained in Impell Calculation No. 271 -101-109, Rev.
O.
Presently the calculation is under review by SMUD.wi% a review completion date of October 31, 1987. '
Corrective Actions - Changes to USAR and Design Process CRTS Data dase Sfoce tJuly,1987 the cable input documents [ Form E1010] have been requf % to carry a designation P [ Power], C [Contrel], or I
[ Instrumentation) to indicate service level and assist in routing the cable in raceways of the proper service level.
Adcitional sarvice level designators are under consideration and include T [TelephorW), S [ Security) and IE [ Instrument-Exempt m1y mix with 9 and/or C cables).
A CRb sof tware enhancement is planned [CRTS Action Item 10] which will:
- Add a field for cable service level [P, C, I etc]
l'
- Add a progrdm' feature to check cele senice level agaf nst raceway service level.
Enclosure To GCA 87-400 Page 26 of 48 ITEM NO. 9 CONTINUED Revisions to P. sgn Documents The physical separation requirements for power, control anu instrument circuits have been defined as follows:
Separate conauits, ducts, penetrations, and cable trays should be provided for the following types of circuits:
(1 ) Medium voltage (6.9kV) circuits.
(2) Medium voltage (4.16kV) circuits.
(3) Low voltage power (480V) circuits from 480V switchgear, with maintained spacing in trays.
(4) Low voltage power (480V and below), control, and annunciator window input circuits, and selected shielded instrument circuits approved by the Electrical and I & C Supervising Engineers.
(5)
Instrument circuits requiring separate routing.
In vertically stacked trays, cable trays should be arranged in the order given above with the medium voltage cables in the highest position in the stack.
i Control cables may be pulled with low voltage power cables, except when their f
respective conductor sizes differ too greatly.
The instrument circuits requiring separate routing are the following:
(1 ) All' signal circuits from process instruments such as thermocouple, RTD's, transmitters, neutron flux detectors, accelerometers, level elements, radiations monitors, etc.
]
t (2) All signal input circuits to computer and Anatec multiplexer,
)
except for selected circuits which the Electrical and I & C l
Supervising Engineers specifically approve in writing for l
routing through power and control raceways.
(3) All low energy level circuits (analog or digital), interfacing between instrument cabinets, and signal output circuits from instrument cabinets which control the plant equipment or device.
(
1-E____
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Enclosure To GCA 87-400 Page 27 of 48 ITEM NO. 9 CONTINUED (4) All circuits requiring coaxial, twinaxial, triaxial, and fiberoptic cables.
(Class 1 ex-core detector cables such as those for source range and power range ion chamber circuits must be run in dedicated rigid steel conduits.)
(5) All low level and higher level analog circuits as addressed in Electrical Design Guide NEPM 5204.43, sections 5.5.4 & 5.5.5.
(6) All signal circuits to panel mounted instruments that are part of a process instrument loop and shown on instrument loop diagrams.
(7) All other circuits designated by the Instrument and Control Group as instrument circuits.
i Revisions to the following Engineering Design Documents were completed l
in July,1987.
These revisions are being be applied to all new cable work.
I
)
NEPM 5204.22 Design Guide - Cable system design, general i
NEPM 5204.43 Design Guide - Instrumentation systems shielding and grounding and surge protection l
Revisions to USAR j
l See commentary to CRTS Action Item ' /.
l i
l Encloscre To GCA 87-400 Page 28 of 48 ITEM NO.10 Description Demonstrate completeness of CRTS including software verification and validation.
COMMENTARY CHRONOLOGY General background and initial actions, concerning tne CRTS program, are described in CRTS Action Item 1 [as-built verification] and 2 [ data discrepancies]. The completeness question has two issues:
1 Installed But Unrecorded Cables: Whether the CRTS data base includes all cables installed in the CRTS listed
- raceways, l
2.
Dependable CRTS Program: Whether the CRTS software is complete, reliable and error free.
Generic Implications 1.
Installed But Unrecorded Cables Cables of two specific systems have been identified as having incomplete cable records:
Security System - CRTS Action Item 11; approximately 180 cables of a total population of 2000 not in CRTS.
Communication System - CRTS Action Item 13; approximately 450 cables, of a total population of 1500, not in CRTS. [ Refer to referenced Action Items for additional detail.]
The possibility has also been raised as to whether procedures existed which permitted cables [other than security / communication] to be installed without entries being made in the CRTS data base.
The procedure question is being investigated by Incident Analysis Group [IAG]. An IAG report is in preparation which indicates no evidence that cables were installed without the CRTS data base being updated.
As of July 1987 the problem of unrecorded cables appears confined to some security and communication systems without generic implication for other systems.
Security and communication cables are installed only in non-safety related raceway which lessens the level of concern.
l l.
Enclosure To GCA 87-400 Page 29 of 48 ITEM NO. 10 CONTINUED Concerns exist, with installed but unrecorded cables, related to raceway weight, to raceway fill and to the quantity of combustible material in open cable trays.
However, the quantities are small and without significant safety impact.
2.
Dependable CRTS Program The CRTS software program was written by Control Data Corporation [CDC] for SMUD. The program was run from 1980 through 1986 on a CDC main frame computer in Kansas City. The program is currently run on a CDC Cyber 180-830 computer installed at the Rancho Seco jobsite. Maintenance and enhancement is provided by CDC. The CRTS data is down-loaded to a network of four personel computers for ease of handling by CRTS personnel.
l The CRTS software program is not a verified program meeting Nuclear Quality Standards. However, subroutines written for and executed on the PC network are verified under a contractor
[Impell] Q. A. program.
The CRTS software program inventories cable and raceway data and perfonns design checks. The CRTS data base is also a source of data for other calculations [e.g. combustible loadings of cable insulation] and a source of information on cable routes. The dependability of the CRTS software is therefore of safety significance to the plant and the software requires verification to the requirements of the SMUD Quality Program.
The design documents issued for construction have always included both the input documents as well as the CRTS generated installation cards. This process provides verification of the cable route since any difference between design intent [ input document] and CRTS record [ output cards]
is readily apparent.
Enclosure To GCA 87-400:
Page 30 of 48 1
ITEM NO.13 Description Show to what extent communication cables are documented in CRTS.
' Comentary :
Chronology 00R 87-409, dated April 9,1987, reports that 630 telephone and security system' cables are installed in the plant with incomplete documentation.
The communication cables include those from the following systems:
PA - Public Address'
[ Dedicated Conduit]
SP - Sound Powered
[ Dedicated Conduit]
CBX. Computer Based
[Non-Safety Tray and Conduit]
Exchange [ROLM]
CBX cables include circuits for VHS radio and microwave link.
Communication cables are shown on series 700 drawings and ECN's.
Generic Implications The concern with the incomplete documentation of the plant communication cables is due to potential impacts upon cable tray weight, fill and j
combustible content as well as separation and mix concerns. However, r
since the communication cables are in either dedicated conduit or in Non-Class 1 raceways, there is no significant impact upon safety cables.
Resolution of this problem will be completed by the end of the
' Cycle 8 outage.
Causes l.
The cause of the incomplete communication cable documentation has not yet been determined. A potential cause is that since the communication 3
cables were installed by the Electrical Maintenance Department, j
conflicting procedures may have led to incomplete communication cable documentation.
Corrective Actions The immediate action to prevent further undocumented communication cable additions to the plant has been.to require all design work to be
)
reviewed by the Nuclear Engineering Department. Additional actions may be taken later after further investigation of causes.
1 j
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f l
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Enclosure To GCA 87-400 Page 31 of 48 ITEM NO.16 DESCRIPTION Define major / minor / insignificant defects.
COMMENTARY CHRONOLOGY The Sample Plan [ Appendix (1)], prepared by Impell under SMUD Task 271, 4
provides in Figures 9.1, 9.2 and 9.3 a flowchart methodology to classify l
the types of defects discovered by the circuit tracing walkdowns, into major, minor or insignificant defects.
The NRC requested in the May 6, 1987 meeting between the District and the NRC, that the District provide formal, written definitions of the types of defects.
Major, minor and insignificant defect definitions were given verbally to l
NRR during a site visit June 15 through 18, 1987. Definitions [see l
below] will be included in the next revision of the Sampling Plan. The following was explained to NRR.
J The word " defect" is used in the Sampling Plan to describe a cable route l
which is checked and found to differ from the CRTS recorded route.
i Defects are classified as either " major", " minor" or " insignificant".
l The classification is determined by reference to a set of decision diagrams included as Figures 9.1, 9. 2, & 9. 3 in the Sample Plan
[ Appendix (1)],
For the convenience of reviewers the following definitions will also be included:
Major Defect A major defect is a cable route which differs from the CRTS recorded route and the difference constitutes a violation of the plant safety or design criteria.
Corrective action is required.
Minor Defect A minor defect is a cable route which differs from the CRTS recorded route and the difference does not constitute a violation of the plant safety or design criteria.
The corrective action is to correct the engineering record with no change to plant configuration Insignificant Defect An insignificant defect is a cable route which differs from the CRTS recorded route only to the extent that typographical errors exist in the recorded data.
The corrective action is to correct the errant data.
Enclosure To GCA 87-400 Page 32 of 48 ITEM ND.19 DESCRIPTION Provide basis for acceptability of 95/95 as sufficient assurance of safety.
COMMENTARY CHRONOLOGY The basis for 95/95 is given in the San'pling Plan [ Appendix (1)].
Cable sampling started in February,1987 and is scheduled for completion in Octobe r, 1987. Following a meeting with SMUD on May 6,1987 and a subsequent telephone conference call on May 11, 1987 the NRC requested additional information.
SMUD RESPONSE The additional information requested is provided in an appendix to this commentary.
Once a joint agreement is established between the NRC and SMUD the Sampling Plan will be revised to reflect the agreement.
The j
appendix has been prepared by a SMUD consultant [Impell] and:
1.
Provides information on established precedents.
2.
Provides additional information on the technical basis for the Sampling Plan and provides a comparison between the Rancho Seco Sampling Plan and Military Standard 105D and related plans.
{
l 1
Enclosure To GCA 87-400 Page 33 of 48 APPENDIX ITEM NO.19 PRIOR USE OF 95/95 ACCEPTANCE CRITERIA IN NUCLEAR POWER PLANT SAMPLING APPLICATIONS INVOLVING SAFETY-CLASS COMPONENTS There are numerous prior instances where the NRC has approved the use of 95/95 sampling plans (i.e. plans which provide 95 percent confidence of 95 percent population reliability) for the sampling reinspection of safety-class components in U.S. nuclear power plants.
One of the earliest such precedents was provided by NRC I&E Bulletin 79-02, which permitted a 95/95 sampling plan to be used to demonstrate the adequacy of installation of concrete expansion anchor bolts. More recently, the NRC approved generic use of the 95/95
]
sampling plan proposed by the Nuclear Construction Issues Group in the document " Sample Plan for Visual Reinspection of Welds," (NCIG-02) Revision 2.
The following are specific plants that are known to have employed 95/95 sampling plans with either NRC concurrence or awareness:
Byron Braidwood j
Clinton San Onofre Unit i Vogtle Palo Verde South Texas Zineer Midland Fermi
)
Watts Bar l
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L__-__-__-______.
Enclosure L,
Page 34 of 48 To GCA 87-400
)
TECHNICAL BASIS i
RANCHO SECO NUCLEAR GENERATING STATION, UNIT #1 SAFETY-RELATED AND SAFE SHUTDOWN CIRCUITS SAMPLING PLAN INTRODUCTION This paper describes the tec%ical basis for the sampling plan developed to evaluate the routing. of safeti, elated and safe shutdown electrical circuits I
.at Rancho Seco Nuclear Generating Station, Unit 1.
Subjects discussed include:
1.
The method for determining minimum sample sizes required to satisfy pre-specified confidence level and. ci rcuit routing reliability criteria.
'2.
Methods employed to select random samp;es of safety-related and safe shutdown electrical circuits corresponding to three different
-(non-overlapping) circuit populations.
SAMPLING PLAN CHARACTERIZATION The ' statistical methodology used to determine sample sizes for three circuit populations at Ranch Seco is the likelihood density function method utilizing inspection by attributes.
This is one of several methods which can be used to obtain a direct estimate of the percentage of discrepant items. in a population from which a
random sample has been drawn.
As described in Goodman
[ References 1 and 2],
the likelihood density function is a normalized likelihood function:
(Equation 1}
f(ele) = f e)de where f(ele) =
the probability density function of the unknown population parameter e
given observed sample evidence e, and L(ele) =
the likelihood of obtaining sample evidence e
given e In the case of sampling by attributes from a finite population, the likelihood
. function L(ele) is the hypergeometric distribution:
[N-m{
L(ele)=L(klm.n,N)= k [~ '
(Equation 2}
\\n)
En cl os u re To GCA 87-400 Page 35 of 48 k $ m, k $ n,'n 5 N, n-k 5 N-m where L(klm.n,N) = the probability of observing exactly k discrepant items in a random sample of size n drawn from a population of size N that contains a total of m discrepant items.
In the case of sampling by attributes from an. infinitely large. population, the likelihood function L(ele) is.the binomial distribution:
in\\
L(ele) = L(kln,p) = kk Pk (1_p) n-k (Equation 3}
O s k>$ n, 0 $ p < 1 where L(kin,p) = the probability of obtaining exactly k discrepant items in random sample of size n where the probability that a given item is discrepant is p.
Normalizing the likelihood functicns gi en by Equations 2 and 3 as denoted in Equation 1, we obtain, for the finite population case, (m)) [N-m[\\
k (n-k f(mik,n,N) =___ \\n)/
lN N-n-k) 1([N-1q ki in-k<
i=k
'N}
inj k)lin-k) m\\
N-m\\
(Equation 4}
=
[N+1}
(n+1; O 1 k 5 n. k 5 m i N - n + k, n $ N where m = the number of discrepant individuals in the population, k = the number of discrepant items observed in the sample, n = the sample size, and N = the population size
Enclosure Page 35 of 45 To GCA 87-400 For the binomial likelihood function L(kln,p), the corresponding likelihood density function is a beta distribution:
1
~
f(pln,k) = k!
! p (1 - p)
, 0 $ k s n, 0 $ p 51 (Equation 5}
n-where n = sample size k = the number of discrepant items observed in the sample, and p = the f raction of discrepant items in th.e (infinitely large) population Using density functions 4 and 5, we can define the F fractile pp according to the formula pF F
f(ple)dp = F g
In the finite population case, this becomes "o
N-m F(m $ m ) =
I "o iN-n+k,
{ Equation 6}
g m=k N+1[
n+1 with parameters as defined for equation 4.
In the corresponding infinite-population case, o
F(p 1 p ) = f (n+ -! p (1-p) dp
{ Equation 7}
g 0
with parameters as defined for Equation 5.
l D
. Enclosure Paae 37 of 48 To GCA 87-400 SAMPl.E SIZE DETERMINATION, Equation 6 was used to determine sample sizes for sampling the three populations of safety-related and safe shutdown circuits at Rancho Seco Nuclear Generating Station Unit 1.
It was specified that samples should be chosen sufficiently large to provide 95 percent confidence that the true percentage of discrepant circuits in the populations f rom which samples were drawn was no greater than 5 percent.
This was achieved by:
1.
Finding the postulated number of discrepant items in the populacion that would be as close as possible to, but not exceed, 5 percent.
discrepant, i.e.,
".o. 1 0.05 (m, an integer)
N 2.
For a defined population size N and various possible values of k (k=0,1,2,3.***n discrepant circuits in the sample), incrementally increase the value of n in Equation 6 such that the computed value of F(m 1 m ) comes as close as possible to (but never less than) the o
target value of 0.95.
This corresponds to a probability of 0.95 that m
the true f raction y of discrepant circuits in the population from which the ' sample was drawn, is no greater than 0.05.
In other words, the sample size is chosen sufficiently large to provide 95 percent confidence that 95 percent or more of the circuits in each sampled population are routed properly.
SAMPl.E SEl.ECTION Random samples of circuits from each of the three populations to be sampled were generated using a computer random number generator.
Within each population,. simple random sampling without replacement was employed [ Reference 3].
Extra circuits were randomly selected to serve as replacement samples in the event that one or more circuits in the p'rimary samples were inaccessible or unusable.
Computerized circuit listings of the three populations to be sampled included some circuits which did not belong to the population being sampled.
The population size provided to the computer random number generator corresponded i
including the to the total number of records (circuits) in the list extraneous circuits.
The extraneous circuits were - manually removed f rom the computer-generated list.
All bona fide members of the population had an equal l
chance of being selected; the sample meets the statistical criterion of a simple random sample [ Reference 4].
Enclosure
(
Pace 38 of 48 To GCA 87-400 COMPARISON WITH OTHER TYPES OF SAMPLING PLANS The type of sampling methodology described above is dif ferent f rom (but no less technically valid than) acceptance sampling by attributes as employed in Military Standard 1050 [ Reference 5].
Military Standard 1050 and related plans employ the statistical methods of hypothesis testing.
The likelihood density function method is based on the statistical method of parameter I
estimation.
While a
Military Standard 1050-type sampling plan is administrative 1y simple and amenable to use by persons unf amiliar with the underlying statistical theory, these plans were primarily intended to be used to help determine a course of action -- not to estimate lot quality.
By design, such plans will end up accepting some lots with poor quality and rejecting some lots with good (ever. superior) quality.
Applying such a plan to an isolated population provides a simple " accept" or " reject" decision but no information whatsoever about the true lot quality.
The likelihood density function method, by contrast, yields a direct estimate of the lot quality, with the precision of the estimate improving as the sample size becomes larger.
It is therefore a true measure of our state-of-knowledge considering all of the available evidence.
A graphical representation of the likelihood density function method of determining minimum sample sizes is illustrated in two enclosed exhibits.
The first exhibit, entitled " Likelihood Density Functions, Circuit Population 3",
shows likelihood density functions for the number of discrepant circuits occurring in Populetion 3.
The different curves shown on the figure correspond to different sample sizes and sampling outcomes for non-replacement sampling from Population 3.
Each curve consists of data points denoted by '+'
symbols, and interconnecting lines of the same color.
The interconnecting lines are provided to aid the reader in distinguishing the general shape of the density function; however, only the '+' symbols have physical meaning since the population. size is finite and the number of discrepant circuits must be an integer.
The above referenced figure illustrates how an increese in sample size increases one's state-of-knowledge about the true number of discrepant items in the population f rom which a sample has been drawn.
As the sample size increases, the likelihood density function becomes narrower and more peaked indicating a sharpening of the precision with which the true percent discrepant in the population can be estimated.
If carried to its logical conclusion - by examining all items in the population -- the density function will continue to narrow and eventually converge on the true value.
Prior to that time, the probability that the number of discrepant items in the population is less than or equal to some value m is given by integrating a
the corresponding area under the probability density function (infinite population case) or summing the individual terms of the probability mass function (finite population case).
Such cumulative probabilities for Circuit Population 3 are shown on the second exhibit.
The curves for the dif ferent..
sample sizes and sampling outcomes are shown to converge at abscissa value ~
m =9 and to pass above the 0.95 cumulative probability boundary at 5 percent o
discrepant.
Thus, all sampling outcomes (n=48, k=o; n=78, k=1;...;
n=146, k=5) yield 95 percent confidence that the true percentage of discrepant circuits in Circuit Population 3 is 5 percent or smaller.
These combinations form the basis for the multiple sampling plan developed for Circuit Population 3.
Equivalent procedures were used to develop the multiple sampling plans for Populations 1 and 2.
En c l o s u re Page 39 of 48 To GCA 87-400 SAMPLE SIZES COMPARED TO A '95/95' ACCEPTANCE SAMPLING PLAN Table 1 compares minimum sample sizes derived using the likelihood density function method and those for a single stage acceptance sampling plan designed l
to provide 95 percent confidence of 95 percent lot reliability.
The latter sample sizes were determined using the equation.
5 Pr(acceptance) = Pr(k a lm.n,N)
{ [iki \\n-kl an m /N-m\\
{ Equation 8)
I k=o lN}
(nj Were an = the acceptance number (a +1=the rejection number) n k = the number of discrepant items in the sample (k=0, 1, 2...a )
n n = the sample size N = the population size m = the total number of discrepant items in the population, and m = the fraction of discrepant items in the population N
The table shows that for a single stage acceptance sampling plan with a =0, n
the required sample size is comparable to that determined using the likelihood density function method.
This remains true for higher values of a
.as long ne as the acceptance sampling plan consists of a single stage.
However, the two methods yield divergent sample sizes when the acceptance sampling plan i
I provides for two or more sampling stages.
For example, a two stage acceptance j
sampling - plan with a =0 for the first stage, a =1 for the second stage, n
n and rejection at r =2 for both stages, will require a greater combined n
sample size than a single stage sampling plan providing for acceptance at a =1 and rejection at r =2.
This is in contrast to the likelihood density n
n function method, where the combined sample size for meeting the 95/95 acceptance criteria at either zero or one discrepant items appearing in the sample is identical to that for a single sample allowing one discrepancy.
The difference between the two methods is attributable to the difference in the mathematical meaning of " confidence".
In acceptance sampling, " confidence" is the conditional probability of rejecting a
lot containing
'X' percent discrepant items, given that a lot of that quality has been submitted.
Using the likelihood density function method,
" confidence" is the conditional probability that the population f rom which the sample was drawn contains
'X' percent or fewer discrepant items, given the evidence available from the sample.
The latter is considered to be the more appropriah definition for the sampling of isolated lots of installed c.omponents at nuclear power plants, and has the added benefit of allowing for multiple sampling with a smaller cumulative sample size than would be possible using acceptance sampling by attributes.
.Enci0sure
.Page 40 of 48 To GCA 37-4001 TABLE 1 CO WARISON OF '95/95' MINIMUM SAMPLE SIZES FOR THE RANCHO SECO UNIT 1 CIRCUIT POPULATIONS - LIKELIH000 DENSITY FUNCTION METH00 VERSUS ACCEPTANCE SAMPLING BY ATTRIBUTES (SINGLE STAGE PLAN)
~
l Method of Discrepancies Confidence Maxim m Percent Circuit Population.
Sanple Size
. Allowed In Sanple Level (%)
Defective In The
-Population Size Determination Sample (a)
Size (b)
Population 1
424 Likelihood 0
52 95.081%-
4.953%
Density 1
424 Acceptance 0
52 94.035%
4.9535 Sangling 1
424 Acceptance 0
52 94.805%
5.189%
Sampling 1
424 Acceptance 0
53 94.372%
4.953%
Sangling 1
424 Acceptance 0
53 95.112%
5.1895 Sangling 2
1702 Likelihood 0
56 95.043%
4.994%
Density 2
1702 Acceptance 0
56 94.594%
4.994%
i
~
Sampling 2
1702 Acceptance 0
56 94.781%
5.053%
Sampling-2 1702 Acceptance 0
57 94.973%
4.394%
Sangling 2
1702 Acceptance 0
57 95.053%
5.053%
Saupling 3
189 Likelihood 0
,48 95.3505 4.762%
Density 3
189 Acceptance 0-48 93.307%
4.,762%
Sampling 3
189 Acceptance 0
48 95.092%
5.291%
Sampling stigt: (a) For acceptance sampling, this is equivalent to the acceptance ntseer; rejection would occur at 1 or more discrepant items in the sample.
(b) For the likelihood density function method, " confidence level" is the conditional probability that the percent discrepant in the total population is less than or equal to the value shown in the last column, given the sangling evidence. For acceptance sangling, " confidence level" is the conditional probability of rejection of a lot with an incoming quality equal to the value shown in the last coltsnn, given that a lot of that quality has been submitted.
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Enclosure Pace 43 of 48 To GCA 87-400 REFERENCES i
[1] Goodman, J., 1984. " Sampling Inspection of Nuclear Power Plants."
Proceedings of the 1984 Statistical Symposium on National Energy Issues, Seattle, Washington, October 16-18, 1984.
[2] Goodman, J., 1985.
" Classification and Comparison of Sampling Procedures."
Transactions of the 8th International Conference on Structural Mechanics in Reactor Technology, Brussels, Belgium, August 19-23, 1985
)-
[3'] Cocharan, W. G.,1977.
Samolino Technioues, 3rd Edition.
John Wiley &
Sons, Inc., New York, New York,128 p.
j
[4] Winkler, R.
L., and W. L. Hayes, 1975.
Statistics:
Probability.
Interference. and Decision, Second Edition.
Holt, Rinehart and Winston, New York, New York, 889 p. + Appendices
[5] Department of Defense, 1963.
" Military Standard-Sampling Procedures and Tables for Inspection by Attributes."
Superintendent of Documents, U.S.
Government Printing Office, Washington, DC.
MIL-STD-1050, 29 April 1963 O
9 s
j' Enclosure To GCA 87-400' Page 44 of 48
-ITEM NO. 20 DESCRIPTION Resolve NRC concerns about possible biasing of sample.
COMMENTARY CHRONOLOGY -
Section 9.1 (3), Evaluation Process, of the Rancho Seco Sampling Plan contains the following statement:
"If a deviation does exist between the CRTS database routing and the "as-built" routing, the results are first checked against existing CPR's or CON's to determine if the deviation has already been dispositioned.
If
{
this problem has been dispositioned by a CPR or CON, no defect for that
'J lot exists."
The question was raised, by Mr. Faust Rosa, at the May 6,1987 meeting as to whether the dispositioning of deviations, by CPR or CON, introduced a bias into the sampling.
SMUD RESPONSE The response to the concern is provided in an Appendix to this commentary.
The process described in Section 9.1 (3) is essentially only a correction of minor bookkeeping errors none of which impacted the cable l
route.
Only seven cables had deviations which were dispositioned as I
described.
All are detailed in the Appendix - and none had deviations i
which affected the route.
No bias was introduced into the sampling by l
Section 9.1 (3). The appendix will be added to the Sample Plan in the next revision.
)
l 1
I
)
Enclosure To GCA 87-400 Page 45 of 48 Appendix To Item N0. 20 TABLE 1 List of. Circuit Tracing Walkdown Cables with CONS or CPRs The following list of cables are part of the CRTS circuit tracing sample cables and have CRTS problems identified as CONS (*) or CPRs(**).
Item Cable Work Request Number CON or CPR Designation i
1 1G1Q886AR 108063 CON-Oll 8 CPR-0053 2
1M1A137 C 127745 CON-0001 3
1P1A06 0 126992 CON-1018 4
1RIC260BB 128755 CPR-0865 5
1RIC469CL 127708 CPR-0031 6
1R21R2H C 127006 CPR-0534 4
CPR-0672 7
1118314 A 127022 CPR-0866
- Conversion error reports (CONS) were generated for equipment, raceway, and cable problems identified from the June,1980 computer conversion error reports prepared by SMUD's contractor, Control Data Corporation, when Bechtel Power Corporation's EE-553 data base was converted to the present CRTS data base.
- CRTS Problem Reports (CPRs) were generated for equipment, raceway, and cable problems identified after the June 1980 conversion.
The following describes the problems and resolutions stated on the associated CONS /CPRs and their impact on the circuit tracing walkdown effort.
1
Enclosure To GCA 87-400 Le Page 46 of 48 Appendix To Item NO. 20 Table 1 (continued)
ITEM 1 Cable: 1G1Q886AR on CON-0118 and CPR-0053 Problems:
CON-0118 states-that the CRTS raceway vias do not match Bechtel's EE-553 cable routing.
CPR-0053 states that the construction card's first and last vias (" red") do not match CRTS first and last vias (" white").
Resolutions:
CON-0118 -- Junction box numbers were removed from CRTS vias and were confirmed by walkdown.
CPR-0053 -- Inspection verified the cable is painted with " red."
0C0 has been issued to correct CRTS.
Walkdown Impact:
None on cable routing ITEM 2 Cable: 1M1A137 C on CON-0001 Problem:
CON-0001 states that CRTS vias show cable tray L43V36 connecting to L39BN5, but CRTS raceway connections do not show them connecting.
Resolution:
CON-0001 -- CRTS Revision Level 1372, 02/16/87, raceway connections show Tray L43V36 connecting to L39BN5.
Walkdown Impact:
None on cable routing
Enclosure.
To GCA 87-400 Page 47 of 48 Appendix To Item NO. 20 Table 1 (continued)
ITEM 3 Cable:
IPlA06 0 on C04-1018 Problem:
CON-1018 states that "from" termination of cable does not match equipment I.D. schedules.
Resolution:
CON-1018 - "From" tennination is a section of a panel. Panel is listed in equipment I.D. schedule.
Walkdown Impact:
None on cable routing ITEM 4 Cable:
1RIC26088 on CPR-0865 Problem:
CPR-0865 states that CRTS shows the cable has a deleted status and removal of the cable is not verified.
Resolution:
CPR-0865 -- Inspection verified tne cable is being spared and has been retagged to IBlPA0101.
Walkdown Impact:
Cable is deleted.
New sample cable selected.
ITEM S Cable:
1RIC469CL on CPR-0031 Proolem:
CPR-0031 states that the pull card is not signed by QC.
Resolution:
NCR was issued and when dispositioned, the pull card will be signed by QC after inspection.
' Walkdown Impact:
None on cable routing
Enclosure
.s 1
To GCA 87-400
?.
I I
Attachment '2 Page 48 of 48 l
\\
l Appendix To Item NO. 20 Table 1 (continued) i ITEM 6
)
[
Cable:
1R2IR2H C on CPR-0534 and CPR-0672 Problems:
CPR-0534 states that the cable is routed in Class 2 overfilled tray.
CPR-0672 states that the construction card has not been received and that the number of conductors does not match design drawings.
Resolutions: CPR-0534 -- Cables in overfilled tray were analyzed.
l CPR-0672 -- Resolution of Non-Class 1 problem on l
unsigned construction cards is not completed.
Walkdown Impact:
None on cable routing ITEM 7 Cable: 1118314 A on CPR-0866 Problem:
CPR-0866 states that CRTS shows the cable has a deleted status and removal of the cable is not verified.
Resolution:
Inspection was performed and confirmed that the cable f
does not exist.
l Walkdown Impact:
Cable is deleted.
New sample cable is selected.
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