ML20205J714
| ML20205J714 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 10/18/1988 |
| From: | Anderson C, Thomas Koshy, Roy Mathew NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20205J706 | List: |
| References | |
| 50-289-88-16, NUDOCS 8810310465 | |
| Download: ML20205J714 (10) | |
See also: IR 05000289/1988016
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U.S. NUCLEAR REGULATORY COMMISSION
REGICN I
Report No.
50-289/89-16
Docket No.
50-289
License No.
OPR-50
Licensee: GPU Nuclear Corporation
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PTBox 480
Riddletown, Pennsylvania
17057
Facility Name: Three Mile Island, Unit 1
Inspection At:
Parsippay _ New Jersey and Middletovn. Pennsylvania
Ins;>ection Conducted: August 29 - September .',1983
Inspectors:
/
/O'N'
Inomas Koshy, $ Piir~hractor Engineer
date
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(
/O /7 N
/M.hoy K. Mathew,
actor Engineer
date
Approved by:
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/v/3' II
C. J. A.
erson, Thief 7PTir,J.,:t'<mssection
date
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Inspection Summary:
Inspection on August 29-31,1988JCorporate_ Office)
}eptember 1-271983_(TNI-3 l' *j - Inspect 1on ReportTo. FO-2iW/88a15
Areas Inspected:
This was an announced inspection to review the licensee's
action on previously identified inspection findings.
Results: No violations or deviations were identifted.
Fiwe unresolved items
were closed. Two deficiencies were noted.
The licenre has not fully
implemented and evaluated the EFV system upgrade.
The adequacy of the diesel
generator capacity was not well supported in the licensee's plant loading
calculations.
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88103 0465 891024
ADOCK 050002G9
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DETAILS
1.0 Persons contacted
1.1 GPU Nuclear Corporation (GPUN)
- A. Agarwal, Instrumentation Manager-
- J. Anger, PWR Licensing Engineer
- G. Braulke, TMI Project
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T. G. Broughton, OTM Director, TMI-1
- L. Cavaliere, Equipment Qualification Engineer
- W. M. Drendall, Instrumentation & Controls Engineer
- R. Ezzo, Electrical Engineer
- B. Gan, Project Engineer
C. E. Hartman, Manager, Plant Engineering
- J. Horton, Engineer-
H. J. Hukill, Director, TMI-1
- D. Hull, Instrumentation & Controls Engineer
C. Incorvati, TMI Audit Manager
B. Knight, TMI-1, Licensing Engineer
- S. Y. Ku, Engineer
- J. Mancinelli, Manage'., Equipment Qualification
D. J. McGettrick, Technical Function, EP&I
R. J. McGoey, Licensing Manager
M. A. Nelson, Manager, Nuclear Safety
- E. Pagan, Equipment Qualification Enginect
- H. Robinson, Electrical Power Manager
- J. Sadauskas, Manager, Electrical Power Instruments
- R. W. Wulf, Manager, TMI Projects
1.2
U.S. Nuclear Regulatory Commission (NRC)
R. Conte, Senior Resident Inspector
- D. Johnson, Resident Inspector
1.3 Pennsylvania State Representative.
A. K. Bhattacharyya, Nuclear Engineer
- Not present at the exit meeting.
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2.0 Purpose
The purpose of this inspection was to review and verify the licensee's
corrective actions for previously identified NRC findings.
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3.0 Followup of Previous Inspection Findings
3.1 Closed (289/86-06-07. Item 2) Qualification of BIW Silicone Rubber
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Cable.
This type of cable is used in specific instrument applications inside
containmont as follows:
-BIW 3/C #16AWG, 30 mils flame retardant Silicone Rubber (SR)
insulation, 45 mils flame retardant Silicone Rubber (SR) jacket
with overall shield.
This cable is used as an instrument cable
for:
RE-TE-1033 (Weed RTO with milli-volt and milli-amp
circuit).
-BIW 4/C #14AWG, 45 mils flame retardant Silicone Rubber (SR)
insulation, 45 mils flame retardant Silicone Rubber (SR) Jacket
with overall shield. This cable is used as an instrument cable
for: WEL-LT-804, WDL-LT-805, WOL-LT-806, and WDL-LT-807.
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(Transamerica Delaval (Gem) Level Transmi6,ters with 115 VAC and
1/2 amp circuit).
No LOCA type test was conducted for this type cable.
However, the EQ
file did contain a BIW test report #B924 which included an oven
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temperature test, a water immersion test, and a radiation test.
To
address the LOCA portion of the type test, the licensee used the LOCA
test reports of the following five cable types. all silicone rubber
insulated:
Test Report #
Manufacture
Cable Tested
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1) Franklin F-C2946
Continental
7/C #12 AWG, 45 mil
2) Anaconda Report
Continental
1/C #12 AWG, 45 mil
No. 79118 on LOCA
3) Rockbestos A-708-86
Rockbestos
1/C #14 AWG, 30 mil
4) Anaconda-Ericson
Anaconda
1/C #14 AWG, 45 mil
report No. 80330-2
Ericson
MSLB test
5) Anaconda-Ericson
Anaconda -
2/C #16 AWG, 30 mil
report No. 81028-2
Ericson
SLB/LOCA test
The tested temperature / pressure profiles enveloped the TMI plant
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profile.
The similarity between the installed cable and the tested
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cables was discussed on page 3 of the EQ supplemental sheet in TMI EQ
file No. TI-163.
The lowest IR measured during the LOCA condition
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was 1 X 10
chms for a length of 20 feet cable.
Based on test data
from the above test reports and the limited application of BIW cable
at TMI, the inspector concluoed that the BIW cable at TMI is
qualificd for its specific application. This item is considered
closed.
3.2 (Closed) Unresolved Item (50-289/87-09-03) Condensate Storage Tank
(CST) Level Oscillations
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The licensee installed new safety grade level transmitters on the
condensate storage tank (CST) suction lines to supply the necessary
input signals for level indications and low-low level alarm as
specified by Regulatory Guide (RG) 1.97 and Restart License Condition
No. 3.a.
Following the installation, the licensee noted large
oscillations in level indications in the control room when the
Auxiliary / Emergency feedwater pump is running.
An initial engineering evaluation of this problem indicated that the
fluctuations in CST suction pressure were induced by fluid flow
dynamics which caused the level signal oscillations.
The licensee
briefed the NRC staff on the problem and committed to upgrade the CST
tank level indication / alarm by the cycle 7 start-up.
The non-safety
related CST level system was placed back in operation to complete the
study on the safety grade transmitters.
The licensee performed the following evaluation of the new safety-
grade level transmitted installation. GPUN Letter 5211-87-2128 dated
June 29, 1967 and the Licensee's Safety Evaluation Report SE
412024-004 Revision No. 4 provided the results of an evaluation of
the unstable CST level indications.
Findings reported that the
low-low level alarms on the condensate storage tanks which are set at
a tank level of 5 feet are connected to pressure transmitters that
are ,nounted in the condensate storage tank drain line.
This
configuration makes the transmitters sensitive to changes in flow
causing an oscillatory input to the indication / alarm circuits.
During the starting of the emergency fksdwater pump and the initation
of flow in the CST drain line, the output of the transmitters may dip
the equivalent of a 3 to 4 foot tank level drop for a very short
duration.
The flow indication later stabilizes at a value of approxi-
mately 0.75 feet below the actual CST tank level due to the Becrinol
effect at the detector.
The licensee concluded that they could reinstate the safety grade
transmitters based on the following reasons. Operations normally
maintains the CST Level at approximately 15-17 feet and the high
level (20 feet), low level (11-5 feet) and low low level approxi-
mately at 5 feet.
If the level droos below the low level alarm set
point which is the minimum technical specification level of 11.2 feet,
the operators must take corrective actions to restore the level within
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
The error in level signal caused by this oscillation and
the steady state error is acceptable due to the followir.g reasons.
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a)
The oscillation is momentary and has not caused the alarm. The
level signal to the alarm is in the conservative direction causing,
at worst, an early low-low level alarm
b)
The level error would not normally activate the low-low level
alarm set point because the tank level must be maintained above
the Technical Specification level of 11.2 feet (150,000 gallons)
c)
If the actual tank level drops below 9 feet during abnormal
plant conditions and a premature low-level alarm occurs, the
operator would have sufficient time to switch to the secondary
source.
This early transfer to the secondary condensate source
is acceptable since it does not create an undue risk to safe
plant operation. Both of these transient and steady state
errors are in the conservative direction.
They would not cause
any substantial operational problems nor any safety concerns.
The inspectors verified the installation and concurs with the
licensee's justification for utilizing the safety grade level
transmitters.
This item is closed.
3.3 (Closed) Unresolved Item (289/86-12-17) Remote Shutdown Panel EFW
Instrumentation Electrical Isolation from Control Room panels and
Seismic Qualification of EFW Digital Indications
During NRC Inspection 86-12 the licensee committed to provide
electrical isolation between the power supplies to the EFW digital
indicators on the remote shutdown panel and the control room panels.
This isolation was considered essential to prevent the loss of both
indications in the event of a puwer supply problem in either of the
locations for any reason including a seismic event.
The inspector
confirmed by a review of Gilbert Orawing 5130-B-600-509, revision
10-0 dated October 27, 1986 that the power supply isolation design
modification provides the required isolation. A review of the
licensee installation confirmed that this modification has been
installed and is operational.
During the NRC Inspection 86-12, the inspector noted that the
electrical isolation would be of significant concern if the control
room indications were not seismically qualified. A failure of the
indicator due to a seismic event could affect the entire safety grade
instrument loop.
During the 86-12 inspection the licensee reported
that the Weston Series 2470 indicators are seismically qualified.
Their qualification was left as an unresolved item pending Region I
review of the licensee qualification data package for these
i n t,trument s .
The inspectors reviewed the Wyle Laboratories seismic qualifications
test report 47430-1 Revision A dated October 3, 1984 for the Weston
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Series 2470 Digital Panel Meter.
This report concludes that "It was
demonstrated that the specimen possessed sufficient integrity to
withstand, without compromise of structure of electrical functions,
the prescribed simulated seismic environment." No discrepancies were
observed.
This item is closed.
3.4 (Closed) Unresolved Item (50-289/86-13-06) Seismic Qualification of
Breaker Modification
The licensee modified the electro mechanical tripping device of
Westinghouse 08-25 and 08-50 breakers with a Westinghouse Ampetector
1A solid state trip system.
During a previous NRC Inspection, the
inspector witnessed the breaker modification.
However, the seismic
qualification of the modification was not available for review.
During this inspection, the inspectors reviewed the seismic
qualification report WCAP 10449 dated January 1984.
This is a
generic qualification report applicable to the solid state
modification of the DB series of Westinghouse breakers. Westinghouse
letter dated September 5, 1985 states that the particular mounting
configuration utilized at TMI-1 is a modified version of the <>riginal
mounting and that Westinghouse has analyzed this configuration as
presented in drawing 4378596. They concluded that it is seismically
qualified for the specified application. This modification provides
better breaker coordination and repeatability of trip
characteristics.
The licensee modified 44 breakers in safety related
applications and 77 breakers in the balance of plant applications.
This item is closed.
3.5 (Closed) Unresolved item (50-289/87-23-01) Evaluation of the
Voltage Dip at the 4160 Volt Bus
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On November 9, 1987, the output voltage of the "1B" auxiliary
transformer (AXT) momentarily dipped.
The "1B" AXT normally supplies
one-of-two vital 4160 kv buses in addition to other non-safety
buses / loads, The voltage dropped down to 2400 volts.
However, the
duration of the voltage drop was not long enough for the time delay
relay to cause the associated emergency diesel generator to start.
Various plant equipment responded to the voltage transient, such as
alternate d.c. powered equipment starting.
The main turbine
experiencert a runback of about 6MW (megawatts). As a result, reactor
power dropped from about 99 percent to abot.t 98 percent.
The plant
was restored to full power short'y thereaf ter.
The licensee review determined th t the voltage dip was a result of
one of the six circulating water pumps (CW-P-1F) for the secondary
plant condenser experiencing an overcurrent situation.
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circulating water pump motor is protected by instantaneous and time
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overcurrent relays in each phase.
The as found settings for the
instantaneous relays correspond to primary currents of 3024A, 2840A,
and 2992A.
If the actual fault currents were lower than these
values, the fault could exist for 4 1/2 seconds or more before the
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relays pickup.
But since the loss of voltage relays (set at 2400V)
actuated, the fault currents had to exceed 10,500 amps prior to
flashing to ground. This is the minimum additional current necessary
to cause the voltage to dip this low. Therefore, the fault flashed
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to ground almost immediately and the ground fault (50G) relay
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responded faster.
Typical response times at the maximum fault
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current would be approximately 1/2 cycle for the phase overcurrent
relays and less than 1/4 cycle for the ground relay (50G).
Electrical faults of this nature are rare where a high fault between
phases lowers the grid voltage substantially for a duration and then
flashe, over to the ground.
The licensee practices on the protection
system was in accordance with Westinghouse Applied Protective
Relaying handbook and 1EEE standard 242-1986 Recommended Practice For
Protection And Coordination For Industrial And Commercial Power
Systems.
The protection system responded as designed. Any prolonged
voltage degradation on the safety bus would have lead to the starting
of the Emergency Diesel generator and isolating the non-safety
related buses which caused the fault. Even though such faults can
influence plant operation, their effect will be limited to one safety
train.
This item is closed.
3.6 [Open) Unresolved Item (50-289/87-02-03) The Emergency Diesel
Generator Load Scheme and The,Use of "0APPER" Computer Program
In the course of respond.ng to action items in NUREG-0737, the
licensee added several loads to the emergency bus which are required
to be energized by the emergency diesel generator.
By letter dated
January 11, 1985 the licensee indicated that their review of the
emergency power bus loadings confirmed that adequate bus capacity was
available to accept the additional loads from the safety system
modification.
The inspectors reviewed Technical Data Report (TOR) 836 "Evaluation
of Loading for the Emergency Diesel Generator and Engineered
Safeguards Buses" dated March 12, 190,7.
The licensee evaluated the
loading under various modes of plant operation, including
simultaneous unlikely events such as loss of redundant power channel
concurrent with a degraded bus voltage and loss of off-site power
concurrent with loss of a redundant power channel.
In the loading calculation, the licensee relies on seasonal load
requirements such as winter emergency loads and summer emergency
loads on plant heating and cooling loads such as air conditioning,
heat tracing, etc. The inspectors questioned this approach as the
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TDR did not contain sufficient bases to support this approach.
There
was no verification data that these loads are prevented from starting
when there is no seasonal demand. The heating and cooling systems
could draw full power when abruptly called upon to operate.
The
licensee is taking actions to reduce the 1E Bus loads and has already
relocated 90 kilowatts of load to a non-safety bus.
The. licensee
stated that it is unlikely that the worst case heating and cooling
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seasonal loads would occur.
They have concluded that their diesels
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are operable.
Should the worst case seasonal loads occur, the diesels
could be loaded to about 3000 kw, the continuous : Jty rating of the
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diesels.
This is below the maximum short term rating of the diesels
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of 3300 kw.
In addition, plant procedures direct the operators to
monitor diesel loading when the diesels start to assure that the
dierels are not overloaded.
The licensee agreed to document their
estimate of the worst case loading within a month.
In addition, the
licensee committed to develop a detailed calculation with sufficient
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bases to confirm the adequacy of the EDG loading oy June 1989.
This
item remains unresolved pending further NRC review.
3.7 (Closed) Unresolved Item (50-289/86-19-02) EFW Back-Up
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Instrument Air Banks orotection from Seismic Missiles
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During a previous inspection, the NRC staff expressed concern about
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the scismic installation ef ducting, piping, and other components
installed above the redundant two-hour backup instrument air banks in
the "B" emergency diesel generator (EDG) room.
The licensee
respondad by indicating that the EDG air intake supply ducting was
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upgraded to meet seismic criteria in accordance with the FSAR
commitments.
No piping is above the air bank.
The remaining cable
and conduit, although not seismically mounted, by engineering
judgement, would not fall and render the air banks inoperable.
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licensee did not provide their basis for this engineering judgement.
A review was made of an engineering analysis conducted by the
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licensee dated August 3, 1987 entitled Technical Assessment on
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Scismicity of Deadweight Supported Domestic Water Piping in the TMI-1
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DGB which is installed above the 2HBUIA.
This analysis is made to
evaluate whether a domestic 1/2 inch copper tubing water line
installed above the air banks represents a seismic hazard to the air
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banks.
The analysis refers to NVREG.1061, Volume #2 Addendum Report
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of the US Nuclear Regulatory Commission piping review committee,
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summary and evaluation of historical strong motion sarthquake seismic
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response and damage to above ground piping, dated April 1985.
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Piping Seismic adequacy criteria recommendations based on performance
during earthquakes, by G. S. Hardy, P. D. Smith and Y. K. Tono,
presented at the symposium on current issues related to nuclear power
plant structure, equipment and piping, North Carolina State
University, December 12, 1986.
The analysis made by the licensee
discusses the various pipe f ailure and failure modes which were
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reported in the two reference documents cited above and relates these
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to the 1/2 inch copper tubing above the air banks.
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The analysis concludes that the domestic water line above the back-up
instrument air banks in the EDG building can withstand an SSE without
falling and damaging the back-up air supply. A review was made of
the licensees seismic evaluation analyses of the EDG air ducts and
air intake filter including its supports.
This seismic evaluation
was made by the licensee's engineering mechanics group under calcula-
tion numbers 1101 X dated May 22, 1980 and calculation number 1101 X
dated May 22, 1980 and calculation number 1101 X -322C-A27 dated
May 26, 1981. As a result this analysis additional supports and
bracing were added to the ducting and the air filter.
The licensee
evaluation concludes that with the additional support in place in
accordance with the details provided by the analyses, the EDG ducting
and air filter do not constitute a missile hazard to the air bands
during SSE. The inspector confirmed the additional support and
bracing t,y a visual inspection.
This item is closed.
4.0 Emergency Feedwater System Upgrades
Durtnc this intpection, the NRC inspectors reviewed certain areas of the
licensee's modification to upgrade the emergency feedwater system to a
safety grade system.
The EFW is designed to initiate on any of the
following signals.
1.
Low level in either OTSG
2.
High Containment pressure
3.
Main Feedwater Loss
4.
Loss of reactor coolant pumps
The inspectors verified the installation of instruments, cable
routing, trays, conduits for high containment pressure signal, a new
signal and main feedwater loss signal, a previously existing signal
to determine the adequacy of the cable routing and installation.
The high containment pressure signal instruments PT1186, 1187, 1188
and 1189 and its respective conduits, trays, cables up to heat sink
protection cabinets were verified and found to be color coded and
installed per GPUs 500 772-A electrical cable and raceway routing
criteria.
However, the existing main feed water loss signal
instruments OPS 829, 542, 543 and 830 sensing lines, trays, conduits
and cables were not upgraded.
TTe licensee considers this to be a
non safety related signal. At nstruments DPS 829 and 542 the
inspectors observed that one if the two mounting U bolts of the
instrument had missing nuts the tubing supports were missing, and
some loose tubing was tied with loose wire to a conduit.
The
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inspectors reviewed the surveillance record in Procedure 1302-06.17
dated June 19, 1988.
This record indicated a random drift of a
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setpoint in the instruments.
The present condition of the instrument
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mounting and the cable routing for the loss of main feed flow signal
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for the emergency feedwater actuation system could lead to undue
challenges to the safety system.
The inspectors relayed these
concerns to the licensee management.
The licensee committed to
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implement corrective action by October 30, 1988.
This is an
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unresolved item pending NRC review of the licensee action to improve
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the reliability of the loss of main feed flow signal
(50-289/88-16-01).
5.0 Unresolved Items
Unresolved items are matters for which more information is required in
order to ascertain whether they are acceptable, violations, or deviations.
One unresolved item is discussed in Section 4.0 of this report.
6.0 Exit Interview
At the conclusion of the inspection on September 2, 1988, the inspectors
met with the licensee representatives denoted in Section 1.0.
The
inspectors summarized the scope and findings of the inspection at that
time.
No written material was provided to the licensee by the inspectors.
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