ML20210N827
| ML20210N827 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 08/12/1997 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20210N826 | List: |
| References | |
| 50-309-97-02, 50-309-97-2, GL-96-01, GL-96-1, NUDOCS 9708260131 | |
| Download: ML20210N827 (13) | |
See also: IR 05000309/1997002
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U.S. NUCLEAR REGULATORY COMMISSION
REGION l
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Docket No:
50 309
License No:
DPR 36
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Report No.
.50 309/97-02
Licensee:
Maine Yankee Atomic Power Company
Facility:
Maine Yankee Atomic Power Station
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Location:
Wiscasset, Maine
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Dates:
February 18 June 18,~ 1997
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Inspectors:
Babu Gupta, NRC Contractor
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George Morris, Reactor Engineer, Division of Reactor Safety
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Approved by:
William Rutand,- Chief, Electrical Engineering Branch
Division of Reactor Safety
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Executive Summary
Maine Yankee Atomic Power Company
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NRC Inspection Report 50-309/97 02
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This inspection included aspects of licensee engineering activities: (1)in response to
Generic Letter 96-01 Logic Circuit Testing; and (2) Cable Separation assessment activities.
The report covers three months of NRC contractor activities and a 2 week review by a
Region i specialist inspector,
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Enaineerina
Cable separation concerns were raised by the licensee during the preparation of
work involved with the logic testing issues. The licensee found examples of lack of
separation between redundant trains of safety related cables that were not in
accordance with the UFSAR. The licensee's independent plant root cause
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evaluation traced the major!ty of the separation problems to insufficient guidance
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during the modification process. However some examples of cable separation
problems were also attributed to original construction. The licensee's plant root
cause investigation of cabl6 separation problems also identified ambiguous and
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conflicting criteria, inadequate drawings, inadequate cable and cable tray labeling
and insufficient training to be significant problem areas. (Se.: tion E1.1)
The licensee's logic circuit testing performed in response to Generic Letter 96-01,
Testing of Safety Related Logic Circuits, identified 102 examples of missing or
incomplete test procedures in the reactor protection system, EDG load shedding and
sequencing, and engineered safety feature actuation logics. The licensee initiated
temporary test procedures which demonstrated the acceptability of those circuits.
(Section E3.1)
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The inspectors identified a weakness in the timeliness of the licensee's evaluation
and tracking of Learning Bank issues associated with the logic testing.
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(Section E3.1)
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Report Details
111. Enaineerina
E1
Conduct of Engineering
E1.1
(Uodate) Unresolved item 50-309/96 14-03. Cable Seoaration
a.
Insoection Scope (37551)
The licensee identified examples of cable separation deficiencies during their
preparation to respond to Generic Letter 96-01, Safety-Related Logic Circuit
Testing. These issues were documented in Licensee Event Report (LER) 96-038-00.
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Those events initiated a broad scope review of the adequacy of cable separation.
NRC Confirmatory Action Letter (CAL No. 1 96-015, dated December 18,1996),
required licensee to perform the following actions to address the cable separation
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concerns prior to restarting the facility:
Develop a plan and methodology for an expanded review to determine the
extent of the cable separation problem at Maine Yankee (MY). The purpose
of that plan must ensure that all safety significant cable separation problems
are identified and appropriately dispositioned or resolved pursuant to the MY
licensing and design bases.
Perform root cause evaluations to address all hardware deficiencies
identified, and utilize this information to validate comprehensiveness of the
MY corrective cetions.
The inspectors reviewed the licensee's criteria for cable separation, the plant root
cause evaluations, cable and raceway walkdown procedures and packages,
performed some independent walkdowns of the raceways under investigation, and
conducted selected interviews to assess the licensee's evaluation and corrective
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actions,
b.
Observations and Findinog
The Maine Yankee cable separation design is described in FSAR section 8.3.7,
Power and Control Cable System, section 8.3.7.5, Cable routing, and section
8.3.7.7, Summary of Criteria. These sections describe a service separation to
segregate cables bases on voltage and function as well as an independence
separation to segregate cables based on redundant functions and safety-related
power supplies.
The inspectors found the licensee had executed the following activities:
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Root Cause Evaluation
The licensee had completed a root cause investigation which resulted in an
initial Plant Root Cause Evaluation Report No. 214 dated January 23,1997.
The licensee indicated they planned a future update to PRCE 214 with their
latest findings from their cable separation review,
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The licensee had initiated a self assessment of MY catd Maration using
industry experts to focus on the effectiveness of the catA separation
program. This assessment by the industry experts had been completed and
documented in a draft report; however, the draft report was not available for
review during the inspection.
Cable Separation Acceptance Criteria
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The licensee had established acceptance criteria for cable separation using
Technical Evaluations (TE). The inspectors found this to be an evolving
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process. The licensee found that the cable separation criteria described in
the UFSAR, section 8.3, had not consistently been applied since commercial
operation of the plant. One attempt had bee 1 the establishment of a
department standard, MYSTD-ELEC-1, Maine Yankee Cable and Raceway
Installation / Removal Standard. This standard was originally issued in June
1987 and was last revised on June 29,1995 (Rev. 8). The licensee found
that even this document did not address all the separation criteria. The
licensee, therefore, established a historical cable separation criteria document
using the technical evaluation (TE) process. TE 226-96, Cable and Wire
Separation Criteria, was prepared for this recent cable separation program
and is now at Rev. 2, dated March 27,1997. This TE has been inturn
supplemented with other technical evaluations which discuss further cable
separation items. These later TEs have also been revised.
Acceptable separation material, except for tray dividers for
train /divisisn/ channel separation, was not identified on plant drawings or
other configuration control documents. Therefore, repairs involving
installation of those materials had not been added to drawings or documents.
The licensee had originally stat 6d that the configuration of the material would
be maintained through procedural processes and limitations, but know
acknowledges the inadequacies of their drawings in this area.
The inspectors observed that technical evaluation TE No. 061-97, Use of
Split Metal Flexible Conduit as a Separation Barrier, permitted flex conduit to
be used in a manner for which it was not originally designed by the
manufacturer. The inspectors reviewed a sampla of separation using this
installation method in cable tray section 321 from the DC power tray. The
inspectors noted the instaliation did not include standard conduit fittings to
protect the cable and was not used as a continuous part of a raceway.
However, the inspectors noted the installation included the application of
glass electrical tape to the ends of the flexible conduit to protect the
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enclosed cabh. Grounding of the isolated flex conduit section also appeared
acceptable. The inspectors found the use of the flexible conduit as a metal
barrier (and not as a UL approved electrical raceway) was acceptable based
on UFSAR section 8.3.7.7, which permitted the use of either flex conduit or
a metal barrier.
The licensee had indicated they were contemplating revising their cable
separation criteria because of the number of apparent cable separation
problems found during their reviews. They wer.' considering the possibility
of taking advantage of the thermal capability of the cables and the protection
and coordination of the circuit electrical protective devices. This item
remains open pending NRC review of licensee's cable separation criteria and
associated corrective actions. (IFl 50 309/97 02 01)
Field Walkdowns
The licensee had performed field walkdowns to identify the deficiencies to
the acceptance criteria. These deficiencies were documented on Deficiency
Tracking Forms (DTF).
The licensee's cable separation review effort was focused on safety-related
power, control and instrument cables and nonsafety related power cables
installed after commercial operation. These latter cables were installed under
the licensee's engineering / design change request (EDCR) process. The
licensee has since identified that this process had deficient separation
guidelines. In addition, the licensee based this focus on EDCR cables after
reviewing the original cable routing design and quality assurance records
from original construction. While the scope of the walkdowns were set by
these EDCR cables, many original construction cables were also included
where they occupied the sarne raceway as the EDCR cables. Although the
licensee's review process did check original construction cables where they
ran with EDCR cables, their sample did not include the entire length of the
original construction cables. The licensee did indicate that approximately
27,000 cable transitions of original cables were included in their review and
only five discrepancies involving original construction cables were found.
The licensee initially divided the Cable Separation Program into 3 phases.
Phase 1 involved a verification of cable separation adequacy within sleeves,
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ducts and embedded and scheduled-exposed conduits which have been
impacted by plant modifications. Phase 2 involved a verification of cable
tray separation and tray-to-sleeve / duct and tray-to-conduit transition
separation. Phase 3 involved an extent of condition assessment of the
separation of the Main Control Board and other selected control panels.
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The licensee completed the Phase 1 walkdowns and evaluations. Phase 2
walkdowns have been completed and evaluations were in progress during
the inspection.
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The licensee performed a visual inspection to support a better understanding
of the original design associated with Phase 3 and the current state of
condition of the wires and cables within the control board. Upon closer
examination of the routing of the conductors through the control board, the
licensee changed the scope of Phase 3 to just identifying the separation
group of safety-related conductors at their termination with color coded tie
wraps.
Walkdown criteria for Main Control Board and Control Paauls had not been
issued prior to the NRC contractor completing his field inspection activities
for this report. There were no Field Welkdown Packages available for the
inspector's review.
Corrective Actions
The inspectors observed that the corrective actions proposed for the
identified deficiencies were separated into minor and major categories.
Minor repairs identified during each phase were performed at the time of the
finding or whenever the minor repairs could be made by the repair crews.
Minor repairs (repairs where cables are not required to be pulled, installation
of separation materials, relocation of cables without re-pulling, etc.) were
being performed without a design change or work order. These minor
activities were, however, being recorded in the "AS LEFT" portion of the
DTF. The inspectors considered this method of tracking minor deficiencies a
seakness in configuration control because they were not documented on the
plant's controlled drawings. The licensee planned to initiate design changes
for any repairs categorized as major repairs (cable pulls, installation or new
raceways, etc.).
The licensee identified in Phase 1 four sleeves or conduits with major
deficiencies. One deficiency was corrected by chble re-pull. The licensee
ntated that the remaining three deficiencies would be addressed as part of an
ntegrated corrective action with other phases.
The inspectors reviewed 9 sleeve walkdown packages and found
discrepancies in six packages. The discrepancies varied from configuration
control problems, lack of detail or explanation, and incorrect disposition (in
violation of the licer see's TE 226-96, Cable and Wire Separation Criteria).
The inspectors identified two examples where the licensee's evaluations also
failed to identify unknown cables in the sleeves. Without knowing the
identification of all cables in a sleeve, a complete evaluation by the licensee
was not possible. This was considered a weakness in the licensee's
evaluation process.
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The population of cables included in the licensee's Phase 2 review included
800 safety-related power, control and instrument cables and nonsafety-
related power cables. Twelve major repair efforts had been scoped which
included approximately 60 spare cables to be removed and approximately
80 cables to be re-pulled, rerouted, or correctly placed within the raceway to
resolve ceparation deficiencies. The licensee found six power cables (feeds
to motor control centers) which will have to be replaced because of failure to
maintain spacing between cables had affected their current carrying
capability. Tracking forms (DTF) had been completed, and most had been
evaluated and closed by the licensee. However, the inspectors found that
individual entries had not been made into the Learning Bank for cable each
separation problem it appeared that the licensee was combining problems
from related DRFs into common Learning Bank issues. While this method
may still provide valid information for a root cause analysis, the inspectors
noted it lacked a quantitative approach. This was considered a weakness in
the Learning Process implementation.
The insper: tors reviewed 5 cable tray sections and inspected the field repairs.
Documentation discrepancies include configuration control problems and not
following procedural details. The inspectors field separation inspection found
inadequate separation in 2 cable tray risers after repairs (PCT-34F 35 RC15
and PCT-34-35 RC18). The licensee indicated they were re assessing their
earlier repairs made for cable trays for several reasons: revised separation
distances, removal of SIL TEMP fire barrier from use, and unclear early work
instructions. MY has issued an additional technical evaluation, TE No.
097 97, Rev. O, Installation of Physical Barriers. The licensee also indicated
they would review the aspect of configuration control for this phase.
The licensee's cable separation efforts for Main Control Board and other
control panels (Phase 3) had not been completed. The inspectors confirmed
that the licensee was identifying safety-related conductors at their
termination locations with color coded tywraps.
c.
Conclusions
The inspectors concladed that the licensee's cable separation review program
demonstrated multiple exemples of the failure of the design controls to effectively
maintain cable separation as defined in the UFSAR. This item will remains open
pending the NRC's review of the licensee's final evaluation and PRCE update.
The inspectors concluded the licensee's cable separation program had a number of
weaknesses including documentation of minor deficiencies, evaluation of unknown
cables in raceways and using common Leaming Bank entries for multiple
deficiencies.
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E3
Engineeri'ig Procedures and Documentation
E3.1
(Uodate) Unresolved item 50-309/96-14-04. Generic Letter 96-01 Loaic Testina
a.
insoection Scoce (37551)
NRC Confirmatory Action Letter, CAL No. 1 96-015, dated December 18,1996,
required the licensee to complete the review of logic testing of safety-related logic
circuits pursuant to NRC Generic Letter (GL) No. 96-01 prior to restarting the
facility.
The licensee was also required to perform root cause evaluations that address all
hardware deficiencies identified, and utilize this information to validate the
comprehensiveness of any corrective actions.
The inspectors reviewed the licensee's GL 96-01 scope and program, selected
control wiring diagrams and temporary test procedures to assess the licensee's
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response to the GL and CAL testing items,
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b.
Observations and Findinas
The inspectors confirmed that the licensee executed the folicwing activities in
response to NRC GL 96-01:
Instituted a Root Cause Investigation which resulted in Plant Root Cause
Evaluation Report No. PRCE 215, Revision 2, dated June 9,1997.
Defineu the GL 96-01 project scope in memorandums PWR 96-006 and PRW
97-019, dated November 8,1996, and February 24,1997, respectively.
Documented deficiencies in the logic testing to comply with scope of
GL 96-01 and entered those items into the Learning Bank.
Prepared temporary test procedures or revised current procedures using
temporary change procedures for identified testing detidancies.
Performed functional testing in accordance with the revised procedures.
The inspectors noted that the Maine Yankee defined scope for the NRC GL 96-01
revie u documented in PRN 97-019 did not include the independent logic circuitry
asssociated with secondary support functions / components. In their letter to the
NRC, MN 97-39 dated February 28,1997, the licensee indicated their test program
will be expanded to include secondary components that must also be operable to
support principal components. Those improvements are expected to be completed
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prior to plant restart.
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The licensee identified examples of logic circuit testing deficiencies during their GL 96-01 program review. These deficiencies were documented in LER 96-043. The
inspectors noted that the LER was revised on April 3,1997, but this latest revision
was incomplete, only addressing the first 70 deficiencies found by the licensee.
The licensee identified 102 deficiencies in their testing procedures as a result of
their GL 96-01 Program reviews. This was in addition to the 15 deficiencies
identified during the August 1996 logic evaluation. The deficiencies were being
tracked by the Learning Process which provideo the licensee's corrective actions for
each deficiency. Only one of the 102 deficiencies (GL 96-01 issue 14, Learning
Bank issue No. 97-00638) involved a potential design error with circuit continuity
lights and did not affect the safety-related function of the circuit.
The licensee prepared composite drawings in preparation for the GL 96-01 program
reviews During this preparation phase, the licensee identified approximately
400 drawing discrepancies which they entered into their Drawing Change Request
process. The licensee evaluated these errors as mostly minor or typographical
errors with only two errors affecting the test program review.
The licensee had completed ten temporary procedures for circuit testing. The
licensee indicated that these procedures accounted for approximately 50% of the
102 deficiencies (principally the deficiencies in tests procedures performed by
operations). The licensee stated that they would incorporate the temporary
procedures into permanent plant procedures and re-perform the testing prior to
restart. The balance of the deficiencies (principally the deficiencies tested by
electrical or l&C) were being resolved by temporary changes to existing procedures.
The testing was performed using the temporary procedure changes (TPC). The
licensee indicated the testing would be repeated using the approsed revised plant
procedures prior to restart. Altogether forty-nine revisions (including new
procedures) were required to the surveillance test program procedures. These
deficiencies appear to demonstrate the inadequacy of the Maine Yankee logic circuit
serveillance test program prior to this review. The licensee also indicated a final
Logic Testing Review report will be developed. This item remains open pending the
NRC's review of the test results using the permanent plant test procedures.
(URI 50-309/96-14-04)
The inspectors noted that Learning Bank event numoer 97 02057, GL96-01
Deficiencies: RPS, had been categorized as a Risk Level 1. This issue, the only one
of three issues associated with the GL 96-01 effort that had not been assigned a
Risk Level 4, had been discovered on February 15,1997. The licensee's procedure
No. O-16-1, Learning Process implementation Procedure, Rev.10, dated
December 27,1997, Section 1.2, described the objective of the Learning Process.
That section stated the objective was to prevent occurrence of significant issues by
thorough evaluations and by effectively tracking corrective actions. Section 6.3,
Issue Screening, included Table 6.3.1, Selection guidance for issue owner and
evaluatica target date. This table identified the department menager as the issue
owner and 3G days as the evaluation target date for Risk Level 1 issues. The
inspectors found that the Learning Bank report, dated May 3,1997, did not have a
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target date for this issue. The lead engineer, not the department manager was
identified as the issue manager, consistent with a Risk Level 4 issue. Event number
97-02053, another deficiency associated with RPS and assigned a Risk Level 1,
was discovered on December 21,1997, but had a target date assigned of
July 15,1997, over 200 days. The inspectors considered these incongruities
between the risk level assignment and the lack of a responsive target date to be a
weakness in the Learning Bank evaluation and tracking process. The licensee has
not submitted their response to the CAL.
c.
Conclusions
The inspectors concluded that MY had establ.ahed a program and procedures to
comply with the GL 96-01 required evaluation. The program was judged adequate.
However, the Project Scope, Review Methodology, and Acceptance Criteria were
initially not defined and documented. Tho inspectors concluded this was a
weakness in the licensee's procedure development process.
E8
Miscellaneous Engineering issues
E8,1
Review of Uodated Final Analysis Report
A recent discovery of a licensee operating its facility in a manner contrary to the
UFSAR description hinhlighted the need for c special focused review that compares
plant practices, procedures, and parameters to the UFSAR description. While
performing the inspection of the MY Cable Separation program, the inspectors
reviewed the applicable portions of the MY UFSAR that pertained to the areas
inspected. Inconsistencies were noted by the licensee and the inspectors between
the wording of the UFSAR Section 8.3 and plant practices and procedures. These
are documented in Section E1.1 of this report.
V. Manaaement Meetinas
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Exit Meeting Summary
The inspectors presented the inspection results to Messrs. R. Fraser, G. Leitch, and other
members of your staff on June 18,1997. The licensee acknowledged the findings
presented. The licensee also agreed that no proprietary information was used during this
review.
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PARTIAL LIST OF PERSONS CONTACTED
Licensee
S. Alexander, OPD
J. Begin, MY
D. Berkland, DED
E. Bingham, MY
B. Blackmore, Plant Manager
J. Bonner, Manager Electrical DED
L. Brown, MY
B. Fraser, Vice President - Engineering
J. Frothingham, Manager - Nuclear Safety Oversight
T. Gifford, MY
D. Kulp, YNSD
L. Lazano, Manager -I&C DED
G. Leitch, Vice President - Ops
J. Mainieu, MY
P. Piezer, MY
B. Snow, MY
J. Tedeschi, Lead GL 96-01 Project DED
S. Urbanowski, Sr. Electrical Engineer DED
J. Weist, Licensing Engineer
R. Willoughby, Licensing Engineer
NBC
W. Rutand, DRS
G. Morris, DRS
J. Yerokun, SRI - Maine Yankee
R. Rasmussen, RI- Maine Yankee
DOCUMENTS REVIEWED
1.
Documents y aich existed prior to the current licensee activities on cable separation:
Maine Yankee Cable and Raceway Installation / Removal Standard, MYSTD-ELEC-1,
Rev. 8 dated June 29,1995 (original issue date June 2,1987.)
2.
Documents generated for the current licensee activities on cable separation:
1.
Cable Separation Program Plan (File: SEN 97-006). dated - February 19,
1997.
2.
Cable and Wire Separation Criteria (TE No. 226-96, Rev No.1 dated
February 11.1997, and Rev. No. 2 dated March 27, 1997).
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3.
Cable Separation Assessment and Walkdown Procedure (Proc. No.17 52,
Rev. No. 3, dated March 7,1997).
4.
Installation of Physical Barriers in the Maine Yankee Raceway System for the
Purpose of Providing Physical Separation of Cables in Accordance with TE
226-96 (TE No. 097 97 Rev. No. O dated March 27,1997).
5.
Root Cat,se Investigation of Cable Separation Problems at Maine Yankee
Atomic Power Company (Plant Root Cause Evaluation Report No. 214,
Report date January 23,1997).
3.
Documents generated for the Generic Letter 96-01 licensee review:
1.
MYPTP-19, GL 96-01 Project Procedure, Rev. No. 3, dated February 12,
1997 and Rev. 4 dated April 10,1997.
2.
Plant Root Cause Evaluation Report #215, Inadequate Surveillance Testing
Procedures, Rev.1, dated January 22,1997 and Rev. 2, dated June 9,
1997.
3.
File No. PRW 97-019, Verification of Project Scope for GL 96-01, dated
February 24,1997.
4.
NS97 030, QA Surveillance for Maine Yankee Project, MYPTP-19, GL 96-01
Project Procedure
5.
GL 96-01 Identified Deficiencies CLOSE OUT PLAN 97 01
6.
GL 96-01 Logic Testing Discrepancies
7.
GL 96-01 Temporary Test Procedures
8.
MY Generic Letter 96-01 Update and Schedule (File: RCS-96-018), dated
Juna 24,1996
9.
MY GL 96-01 Temporary Test Procedures
10.
MYP 97-0247, GL 9601 Project Results, dated May 1,1997
4.
Other miscellaneous reference documents:
1.
MN-96-52, MY letter to NRC, dated April 19,1996
2.
MN-96-123, Charging /High Pressure Safety injection Pumps
3.
QA/OC Surveillance Report, Surveillance No. 96S-031
4.
MY Proceduto 0112, Surveillance Tests and Records, Rev. 7
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DTF
Deficiency Tracking Form
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EDCR
Engineering / Design Change Request
GL
Generic Letter
IFl
Inspection Followup Item
MY
Maine Yankee
PRCE
Plant Root Cause EvaluaCon
Technical Evaluation
TPC
Temporary Procedure Change
Updated Safety Analysis Report
Unresolved item
UL
Underwriters Laboratories
YNSD
Yankee Nuclear Services Division
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