ML20044E271
| ML20044E271 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 05/17/1993 |
| From: | Huber M, Jeffrey Jacobson, Replogle G, James Smith NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20044E264 | List: |
| References | |
| 50-346-93-09, 50-346-93-9, NUDOCS 9305240123 | |
| Download: ML20044E271 (9) | |
See also: IR 05000346/1993009
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U. S. NUCLEAR REGULATORY COMMISSION
REGION Ill
Report No. 50-346/93009(DRS)
Docket No. 50-346
License No. NPF-3
Licensee: Centerior Energy
c/o Toledo Edison Company
300 Madison Avenue
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Toledo, OH 43652-0001
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Facility Name: Davis-Besse Nuclear Power Plant
Inspection At: Davis-Besse Site, Oak Harbor, OH 43449
Inspection Conducted: April 19 through 29, 1993
1nspectops:
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J.' W. Jatobson, Chief
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V1'ateria10 Processes Section
Inspection Summary
Inspection conducted April 19 throuan 29, 1993 (Report No. 50-346/93009(DRS))
Areas Inspected: Announced safety issues inspection of the licensee's
inservice testing program (TI 2515/114), the licensee's program an check
valves (TI 2515/110), and licensee self assessment in these areas.
Results: The inspection disclosed one unresolved item (paragraph 2.b.(4)) and
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three inspection follow-up items (paragraphs 2.a.; 2.b.(1); and 2.c.(2)).
The licensee demonstrated a weakness in the following area:
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The f ailure to consider gage inaccuracies and allowable differences in
flow settings for testing of the auxiliary feedwater pump.
9305240123 930517
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Inspection Summary
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The licensee demonstrated strengths in the following areas:
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A proactive approach to check valve reliability as evidenced by the
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early start of the check valve program.
Management support of personnel participation in technical organizations
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dedicated to improvement of pump and valve reliability.
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TABLE OF CONTENTS
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Pace
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1.
Persons Contacted................................................
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2.
Inservice Testing of Pumps and Valves............................
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a.
Program Scope............................................
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b.
Pump Testing..............................................
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(1)
Flow Bands...........................................
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(2)
Averaging............................................
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(3)
Stabilization......................................
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(4)
Acceptance Criteria...........................
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(5)
Auxil ia ry Feedwater Fl ow. . . . . . . . . . . . . . . . . . . . . . . . . . . .
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c.
Valve Testing..............................................
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(1)
V al v e T e s t i n g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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(2)
Relief Valve Testing..........................
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3.
Check Valve Program..............................................
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a.
Program Scope..............................................
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b.
Basi s for Including or Excl uding Val ves. . . . . . . . . . . . . . . . . . . .
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c.
Non-Intrusive Testing Methods..............................
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4.
Trending. .......................................................
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5.
Post Maintenance Testing........................................
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L i c en s ee S el f- As s e s smen t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Unresolved
Items.................................................
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8.
Inspection Follow-up ltems......................................
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9.
Exit Meeting.........
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DETAILS
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1.
Persons Contacted
Toledo Edison (TEl
S. Jain, Engineering Director
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J. Barron, Supervisor, Test Engineering
E. Caba, Manager, Performance Engineering
G. Christen, Check Valve Coordinator
G. Gibbs, Director, Quality Assurance
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J. Hayes, Senior Nuclear Technologist
G. Honma, Supervisor, Compliance
M. Parker, Supervisor, Station Performance
R. Schrauder, Manager, Nuclear Licensing
D. Schreiner, Supervisor, Performance Engineering
J. Staudacher, Check Valve Reliability
A. VanDenabeele, Supervisor, Engineering Assurance
Nuclear Reaulatory Commission (NRC)
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S. Stasek, Senior Resident Inspector
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K. Walton, Resident Inspector
All of the above individuals attended the exit meeting on April 29.
1993.
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2.
Inservice Testina (IST) of Pumos and Valves
a.
Proaram Scope
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The scope of the program was generally acceptable. The principal
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anomaly was the exclusion of thermal relief valves from the IST
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program. This did not conforc to the requirements of the 1986
edition of the ASME Code.
However. this practice was allowed in
the version of the Code to which the licensee was previously
committed.
In response to the inspectors' concerns, the licensee
initiated steps to identify any thermal relief valves that may
have been inadvertently excludec from the program. This issue is
considered to be an inspection follow-up item pending further NRC
review of the corrective actions (50-346/93009-01(DRS)).
b.
Pump Testina
(1)
Flow Bands - The IST procedures for pumps included a
tolerance band on the reference value for flow. The purpose
of the band was to relax the requirement to obtain at fixed
flow reference value for each test. The use of a tolerance
band however, may not meet the intent of the Code.
In
response to the inspectors concerns, the licensee initiated
steps to ensure that all the pump tolerance bands would be
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limited to a maximum of 2% of the reference value. The
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Office of Nuclear Reactor Regulation (NRR) indicated that
this was a generic issue throughout the industry and that
guidance would be issued in the near future addressing
acceptable tolerance bands. However, justification of
tolerance bands in excess of 2% was expected to be unlikely.
This issue will be considered an inspection follow-up item
pending issuance of the generic guidance from NRR, and
satisfactory incorporation of this guidance into the IST
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program (50-346/93009-02(DRS)).
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(2)
Averaaina - When pump testing was performed, data from
several test runs were averaged and evaluated as if the
cumulative testing effort were a single test, although the
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ASME Code, IWP 3100, appeared to require a separate
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evaluation for each test. The NRC inspectors expressed
concern because the data from several tests could be
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combined to mask non-conformances that would be evident in
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individual tests. However, the licensee's approach may have
merit, because the results could demonstrate more consistent
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pump performance because of the longer time interval
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required to obtain data.
In response to the inspectors'
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concerns, the licensee agreed to submit a Code inquiry to
resolve the concern and to request relief from the NRC in
the interim.
(3)
Stabilization - The procedures that controlled the testing
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of the auxiliary feedwater (AFW) pumps did not specify the
five minute stabilization period required by the ASME Code,
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IWP-3500. However, in response to the inspectors' concerns,
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the licensee performed an evaluation and determined that the
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complexity of the procedures and the familiarity of the
operators with the ASME requirements would assure that at
least five minutes would have expired prior to the recording
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of previous test data.
Additionally, steps were initiated
to include requirements for a five minute wait period in the
appropriate procedures to cover future tests. The
inspectors considered these actions to be acceptable.
(4)
Acceptance Criteria - The differential pressure acceptante
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criteria specified for the AFW pumps did not include margin
to account for variations in gage inaccuracies and
differences in flow settings. The acceptance criteria were
based on the minimum pump discharge pressures specified in
the UFSAR. These limits were more restrictive than those
specified for IST in the Code.
Since IST was the only means
employed to demonstrate pump operability, the licensee was
requested to formally respond to this issue. This response
should address corrective actions taken to resolve the
matter and any impact on previous tests. This item is
considered to be an unresolved item pending NRC review of
the licensee's response (50-346/93009-03(DRS)).
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(5)
Auxiliary Feedwater Flow - The testing of AFW turbine steam
supply check valves prescribed by procedure DB-SP-03151 used
a " flow criterion" of 3582' rpm in the AFW turbine. This
criterion was to define a flow of sufficient steam to
produce an auxiliary feedwater flow of 600 gpm. Although a
review of the pump curve confirmed that the required 600 gpm
flow could be delivered at 3582 rpm, the actual feedwater
flow requirement is the criterion which should be specified,
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because degradation of the pump or maintenance activity
could result in a delivery of less than 600 gpm at 3582 rpm.
c.
Valve Testina
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(1)
Valve Testina - The inspectors reviewed IST procedures and
completed IST surveillance data. Generally, the methods
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used for testing of valves were adequate. The test
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frequencies and acceptance criteria were specified and
provisions were made for prompt operability determinations.
(2)
Relief Valve Testina - The criteria used at Davis-Besse for
requiring the testing of additional valves when a relief
valve failed a setpoint test were different from that
normally seen by the inspectors.
The licensee used the
nominal setpoint pressure range plus or minus three percent
to determine when additional relief valves needed to be
tested. The inspectors position was that additional valves
needed to be tested when the results of the original test
sample exceeded 103 percent of the nominal setpoint
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pressure.
IWV-3512 of Section XI of the ASME Code states that relief
valves should be tested in accordance with ANSI /ASME OM-1-
1981. OM-1-1981 defines the rules and requirements for
cerformance testing of pressure relief valves. The GM Code
requires that two additional valves be tested fcr each valve
f ailure up to the total number of valves of the same type
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and manufacture when a valve exceeds the stamped set
pressure criteria by 3 percent or greater.
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The licensee interpreted the words " stamped set pressure
criteria" to be the allowable setting range defined by the
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licensee. The range was based on the more restrictive
requirements of either the design basis margins or the
technical specifications. When the licensee then applied
the three percent tolerance, it was applied to the
extremities of the allowable setting range, rather than to
the nominal stamped set pressure.
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This approach to setpoint testing was being submitted to the
ASME as a Code case.
The licensee reviewed all testing
performed during the last outage, which was the first time
these criteria were applied. After reviewing these test
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results, the licensee concluded that, to date, no additional
testing required by the old criteria had been avoided by
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using the new criteria and' that there will be no additional
testing until the next outage. The Code case is expected to
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be resolved by that time and the licensee agreed to respond
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appropriately.
Pending resolution of the Code case, the
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adequacy of the licensee's methodology for performing
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additional relief valve testing following failures is
considered an inspection follow-up item (50-346/93009-
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04(DRS)).
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Check Valve Proaram
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a.
Proaram Stone
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The check valve program was generally considered to be accept- ble.
It consisted of two parts: (1) the Inservice Testing Progrr
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developed in response to Generic Letter 89-10, and (2) tha
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Valve Reliability Program (CVRP). The CVRP was developed i.,
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response to SOER 86-03 as well as to internal reviews performed
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both before and after the SOER.
Subsequently, the licensee
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engaged a consultant to perform predictive wear analyses for
approximately 135 check valves.
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Preventive Maintenance Activities were generated based on the
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inspection findings from the CVRP, CVRP wear analyses, and a
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review of check valve maintenance history.
Valves which had
potential for degrading the system were replaced, removed, or
modified to overco"e the problem.
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The IST program int.uded 118 check valves and the CVRP included
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168 check valves. All 118 IST check valves were included in the
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CVRP. This was considered to be a good overlap between the
programs. Selected plant systems aere also reviewed to ensure
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that the scope was adequate.
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b.
Basis for includina or Excludino Valves
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The licensee adopted a conservative approach to determining which
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valves should be in the program. The program was designed to
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include all the valves prescribed in 50ER 86-03.
It also provided
for the testing of some check valves not prescribed in the 50ER,
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for which testing was desirable.
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The licensee deleted certain valves from the program on the basis
of function (i.e., valves used for operating convenience or
maintenance only) but not for size or design.
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Non-Intrusive Testina Methods
The licensee has actively folloded the development of non-
intrusive testing (NIT) for check valves through association with
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EPRI and Utah State University. The licensee also participated in
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the EPRI Working Committee for Check Valves (NIC) and is
coordinating their NIT effort with the Perry Nuclear Power Plant
to assure compatible systems and comparable data.
The first application of NIT to plant valves was performed by
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vendors of acoustic monitoring equipment, using their own trained
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personnel. After evaluating the results of these inspections, the
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licensee riccted to develop an acoustic monitoring system in-
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house, using commercially available components. That system was
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being applied to plant valves at the time of the inspection.
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licensee's written plan for NIT includes the addition of magnetic
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proximity-measuring oevices to the existing equipment in order to
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improve its reliability for predicting valve condition. The use
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of two different systems to improve reliability is in accordance
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with the industry position in this afea.
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4.
Trendina
The trending program for maintenance, failure and test results for check
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valves, pumps, and valves was acceptable. Several of the documents
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reviewed confirmed the licensee's use of information available in NPRDS,
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VETIP, and plant and industry experience. Trending of dimensional data
for detecting wear was in its initial phase, so no changes from wear,
vibration, or impact could be traced.
5.
Post Maintenance Testina
Post maintenance testing (PMT) activities were prescribed for routine
operations and were generally acceptable. Although the PMT was
identified in a written procedure, it was not a mandatory minimum.
Imposition of necessary testing was assured only by having each work
order reviewed by a specified expert in the area. The efficacy of the
program is entirely dependent on the judgement of an individual.
The
inspectors considered this to be a less rigorous trethod than specifying
minimum acceptable testing and preparing written justification for any
exceptions.
6.
Licensee Self-Assessment
The licensee's self-assessment plan is generally acceptable. The
subject matter and depth of reviews were appropriate, but responses were
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occasionally poorly documented.
For example, the response to one
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recommendation in NE0-93-00035 indicated that resolution of a finding
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was performed and documented, but failed to identify the document or
show where it might be found.
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Unresolved Items
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Unresolved i' ems are matter: about whith more information is required in
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order to ascertain whether they are acceptable items, violations or
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deviations. An unresolved item disclosed during this inspection is
discussed in Paragraph 2.b.(4) of this report.
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Inspection Follow-up Items
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Inspection follow-up items are matters which have been discussed with
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the licensee, which will be reviewed further by the inspectors, and
which involve some action on the part of the NRC or licensee or both.
Inspection follow-up items disclosed during the inspection are discussed
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in paragraphs 2.3., 2.b.(1), and 2.c.(2) of this report.
9.
Exit Meetina
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The inspectors met witi licensee representatives (denoted in Paragraph
1) at the conclusica of the inspection on April 29, 1993. The
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inspectors summarized the purpose, scope and the findings of the
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inspection and discussed the likely informational content of the
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inspection report. The licensee did not identify any of the documents
or processes reviewed by the inspectors during the inspection as
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proprietary.
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