IR 05000458/1989036
| ML19325E927 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 10/31/1989 |
| From: | Constable G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML19325E924 | List: |
| References | |
| 50-458-89-36, NUDOCS 8911130039 | |
| Download: ML19325E927 (11) | |
Text
-
.
._.._
{ 2:
.o E
l '. c,
,
<.., -
.j
'
,_
j
.
,
6:
j APPENDIX l
L U.S. NUCLEAR REGULATORY C0lHISS10N i
'
'
'
REGION IV
,
i n
NRC Inspection Report:
50-458/89-36 Operating License:
NPF-47 l
.
.
J
'
Docket: 50-458
.
Licensee:
GJ1fStatesUtilitiesCompany(GSU)
l
'
c P.O. Box 220
St. Francisville, Louisiana 70775 l
i Facility Nane: River Bend Station (RBS)
i
!
Inspection At: RBS, St. Francisville, Louisiana j
Inspection Conducted:
September 1-30, 1989 l
,
Inspectors:
E. J. Ford, Senior Resident Inspector
,
W. B Jones, Resident Inspector
f I
'
/o/v/99 l
Approved:(.
~~I
-
~
G. L. Constable. Chief, Project Section C Date /
,
Division of Reactor Projects j
-
Inspection Sunnary
'
t Inspection Conducted September 1-30, 1989 (Report 50-458/89-36)
Areas inspected: Routine, unannorn u d inspection of followup of events,
,
operations safety verification, maintenance observation, surveillance te:;t
.
observations, and potential 10 CFR Port 21 followup.
l
!
Results: Within the areas inspected, no violations or deviations were identified. The reactor operatort <iemonstrated the. ability to deal with an
unexpected: reactor scram (Scram 89-03) in a manner which minimized the transient imposed on the plant. Af ter appropriate corrective actions and evaluations,
the operators returned the plant to power in a professional manner. They
properly utilized and complied with various operating and administrative
procedures during the scram and subsequent startup. Maintenance and
!
surveillance activities were conducted in accordance with the controlling
'
documents.
]
!
8911130039 891 g 0 DR ADDCK 050
>
,
I
r
-
.
>.'
.
)
,
.
?
-2-
I
DETAILS
!
1.
Persons Contacted
- J. E. Booker Manager, Oversight
- J. L. Burton, Supertisor, Independent Safety Engineering Group
!
E. M. Cargill, Supervisor, Radiation Programs
- J. W. Cook, Lead Environmental Analyst, Nuclear Licensing
'
- T.C.Crouse, Manager.QualityAssurance(QA)
- W. L. Curran, Cajun Site Representative
- J. C. Deddens, Senior Vice President, River Bend Nuclear Group D. R. Derbonne, Assistant Plant Manager, Maintenance
- L. A. England Director, Nuclear Licensing r
- R.. W. Frayer, Director, Projects i
R. G. Finkenaur Electrical Engineer
A. O. Fredieu. Supervisor, Operations
'
- P. E. Freehill, Outage Manager
,
- P. D. Graham, Executive Assistant to the Senior Vice President
,
- J. R. Hamilton, Director Design Engineering
'
G. K. Henry, Director. Quality Assurance Operations D. E. Jernigan, Instrumentation and Control Supervisor
- G. R. Kimmell, Director Quality Services
'
J. W. Leavines, Director Field Engineering
- W. H. Odell, Manager Administration
- T. F. Plunkett, Plant Manager
- J. P. Schippert Assistant Plant Manager, Operations R. J. Vachon, Senior Compliance Analyst J. Venable, Assistant Operations Supervisor
- D. H. Wells, Senior Licensing Analyst
-
,
l
- R. G. West, Supervisor, General Maintenance t
The NRC also interviewed additional licensee personnel during the
[
inspection period.
'
- Denotes those persons that attended the exit interview conducted on
i October 13, 1989, i
2.
Plant Status After reducing power in August to work on the B" feedwater pump, the unit
.
'
achieved full power on August 25, 1989, and remained at full power throughout the month of September.
However, on Septerber 30, 1989, during
'
the performance of surveillance testing, the reactor scransned from
.
80 percent power for reasons unknown at that time. Licensee investigations
',
later disclosed that a faulty test switch had cauted the scram. Subsequent to cause analysis, corrective maintenance actions, and retesting, the unit was returned to full power.
.
b
.
__
_
_..
'
-
-
cj
..
..
,
i
.
<
a-3-r
!
!
3.
Followup of Events (93702)
During this inspection period, the inspectors reviewed licensee condition i
reports (CRs) and 10 CFR 50.72 reports and held discussions with various i
plant personnel to ascertain the sequence, cause, and corrective actions i
taken for plant events. Discussion of a selected event is given below:
a.
Reactor Trip On September 30, 1989, at approximately 3:40 a.m., the reactor
!
tripped. The cause was not innediately obvious.
At the time, the I
licensee was conducting a Technical Specification (TS) required
functional surveillance test of the main steam isolation l
nonthly(MSIVs.
(See paragraph 6 for a discussion of the
!
valves surveillance.
.
MSIV closure is sensed by the reactor protection system (RPS).
Parameters such as steam flow and pressure, steam line radiation, steam tunnel temperature, and reactor water level are monitored and i
abnornal readings will cause the MSIVs to close, thus isolating the
main steam lines. The reactor is then scramed by the RPS in
,
anticipation of the pressure and flux transients resulting f rom this.
i isolation.
(1) RPS System Overview of Nonnal Operation The RPS is composed of two independent trip systems. A trip
-
from either channel (Channel A or C) in Trip System A and a trip from either channel (Channel B or D) in Trip System B wit 1 t
generate a reactor scram signal. This is referred to as a "one
out of two twice" logic. A trip of only one of the trip systems
.
is referred to as a half-scram and will not generate a reactor
scram signal.
l Each trip channel consists of a series pathway of normally
-
closed relay contacts which remain closed as long as the
corresponding monitored plant parameter stays within specified limits.
(Typical parameters nonitored am:
turbine valve
'
,
position, drywell and reactor pressure, reactor vestel levels, and MS!Y position.)
If a parameter exceeds a preset value, its contact opens causing f
rela s to deenergize, thus putting that channel in a tripped state.
j During a scram, both RPS trip systems de-energize, which i
de-energizes both solenoids on the scram pilot valves to cause the scram.
l
'
.
. -
_
- _
.
- -
.
. -
_
_
-
-
-
-
_ -
_ _. -
.
.
.
.
.
'.
.
,
'
i-4-
,1 (2) Main Steam Line (MSL) Isolation I
l The MSL isolation scram setpoint (any three lines with valves
)
less than 90 percent full'open) is selected to give the earliest
positive indication of MSIV closure and still allow functional i
testing of MSL isolation trip channels with one steam line
'
1solated. A normal test of MSIV closure will cause a half scram. 'To produce the half scram, it is necessary to position a
!
test switch to the test position. By doing so, one of two l
paralleled contacts-are opened.
l
The test switch is a key switch which requires a ke to be i
inserted in order to move the switch from the NORMA positioni l
Normally, the key cannot be removed unless the switch is in the s
NORMAL position.,
The effect of the switch in TEST is that for either test
position it opens one side of the parallel branch circuit. When i
in NORMAL, the circuit is undisturbed.
The test switch associated with Channel D was defective. The
'
operator, at the conclusion of the previous months testing, had rotated and extracted the key (indicati19 that the switch had i
been returned to NORMAL); however, the test contacts were still
.
open.
,
'
GE design philosophy does not provide for an annunciator for this switch because it does not bypass a safety function. Thus, i
there was no indication available to the operators to warn them
!
of this condition.
Further, the relay for trip Channel D
!
remained energized and no alarm was annunciated because a half i
scram is not present.
l When testing comenced on September 30, 1989, a " portion" of a half scram was in place but was not detectable by visual observation or annunciators. As testing (by actually stroking the MSIVs) progressed, the expected half scrams were being produced properly until the "C" MSL was exercised. Channel C deenergized its relay and produced a half scram and a side branch for the D channel was also open (due to the defective i
switch) and both trip systems were in a condition to generate the full reactor scram.
,
'
.
b.
Reactor Trip Followup The inspector reviewed CR 89-1070 associated with the scram and the written statements of the engineers. operators, technicians, and craft foreman on duty at the time. The inspector verified that the 10 CFR 50.72 (nonemergency) 4-hour notification was made within the require:d time (the call was made at 6:59 a.m.).
The inspector aisc
,
-
-,, -
. _ _
_
'
.. h
^
<
.
,
'!
'
,
E-5-
)
I l
reviewed the following documents associated with the scram package
]
(Scram 89-03) for proper implementation.
General Operating Procedure GOP-0003, " Scram Recovery" which I
includes:
n
,
Posttrip Review Checklist
,
Scram Report
-
>
Perfonnance Package
-
k A review of the control room log for the 6 p.m., to.6 a.m. shift
disclosed that the plar,had started a routine power reduction to 80 percent power shortly after midnight and achieved this power level
- '
a little more than 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> later.
The 3:40 a.m. entry states:
" Reactor scranned while performing STP-051-0201, Step 7.5.4."
Various entries subsequent to this indicate the appropriate use of
~
the abnonnal operating procedures.
The inspector reviewed drawings, the surveillance test in use (see I
paragraph 6), and discussed the involved circuitry'with technicians
and engineers to independently verify the licensee s evaluation of
the cause of the trip.
No violations or deviations were identified.
4.
' Operational Safety Yerification (71707)
The * Spectors observed operational activities throughout the inspection
!
period at) closely monitored operational events.
Control room conduct and
!
'
activities were generally observed to be well controlled.
Proper control
room staffing was maintained and access to the control room was well
'
controlled.
Selected shift turnover meetings were observed, and it was s
found that detailed information concerning plant status was being covered.
Several control board walkdowns were conducted by the inspectors.
In all
cases, the responsible operators were cognizant as to why an alann was lit and the reason for each plant configuration. Operational conditions and
events identified through discussions with the reactor operators and
review of the shif t turnover logs were identified in the main control room
'
log.
Inoperable equipment, identified during the main control board
'
walkdowns,(were identified by the applicable limiting condition for operation LCO).
.
'
The inspectors conducted several tours of accessible areas of the facility during this inspection period. General housekeeping practices were found to be adequate. Walkdowns of the A and B residual heat removal systems were conducted. Major flow path valves were verified to be in the required standby position. The associated power supply for each major flow path valve and pump was observed to be available. No conditions were f
...,
-
--
- -
.
-
-
-
-
F
-
,
>
.
,
p4q
_c>
,
.
,
'
l-6-
'
m.
.
'
noted whicti would indicate the associated system would not perform its L
intended safety' function.
The inspectors verified that selected activities of the licensee's radiological program were implemented in conformance with facility I
,
policies, procedures, and regulatory requirements.
Radiation and/or
.
.
>
.
contaminated areas were properly posted and controlled.
Radiation work
'
permits contained ' appropriate information to ensure that work could be
[:
. performed in a safe and controlled manner.
Radiation monitors were properly utilized,to check for contamination.
During plant tours, the
'
. inspectors frequently checked calibration stickers on various radiological monitoring equipment and physically verified that selected very high
>
i radiation area access control doors were locked and closed.
The inspectors observed security personnel perform their duties of personnel and package search.
Vehicles were properly authorized and controlled or escorted within the protected area (PA).
Personnel access i
was observed to be controlled in accordance with established procedures, i
The inspectors conducted site tours to ensure compensatory posts were
'
'
properly implemented 'as required because of equipment failure or degradation.
The PA barrier had adequate illumination and the isolation zones were free of transient materials.
The licensee operated the plant
-
in a safe,' controlled manner during this inspection period, l
.No violations or deviations were identified,
,
'
S.
Maintenance Observation (62703)
l On' September 16, 1989, the licensee had indications of a loss of.the "B" train instrument bus panel (SCM*PNLIB).
Further investigation by the operators disclosed evidence of combustion products,in the vicinity of the power line conditioner (SCM*XRC1481) which feeds the ' panel.
This is a 480 Vac to 120 Vac transformer.
The power.line conditioner (PLC) was severely damaged and maintenance activitics were initiated to replace the item.
The inspector observed the extent of the damage to the PLC and reviewed the associated documentation.
Licensee personnel initiated CR 89-1037, dated September 16, 1989.
The licensee's initial failure anelysis was
'
based on visual observation and determined that a failure of the main 480 Vac step down transformer had occurred.
The licensee's interim disposition recommended:
that power supply cables,between the PLC and the instrument bus panel be meggered,'
,
that the alternate power supply to the "B" RPS bus (transformer 1RPS*XRC1081 - this is not required for the "B" RPS by the RBS TS) be utilized,
,
e
'
n.
-
,
o
-
,
-
..
.....
..
I.
-
-7-
,
x
,
N that the neutral ground strap in the instrument panel be repaired.
(MWO-R056460 was used for this), and I
.that power be restored to the panel one load at a time verify 49
proper restoration of systems.
"
The above recommendations were implemented by the licensee utilizing
Modiation Request PMR 89-25. The inspector reviewed the following documution associated with this maintenance action:
h!Ication Request PMR 89-25
'
Design Review Checklist
[
.Civib* Structural Evaluation Checklist
!
u Departmental Work Responsibility Check'aists
- -
Equipment Qualification Impact Review Checklist
!-
'
Fire Protection Review Checklist Equipment Qualification Impact Sumary (EQIS)
i
[.
'
Security Considerations Checklist
- l
- <
,
}-
Design Input Guidelines
Initici Safety and Environmental Evaluation
.
..
Unreviewed Safety Question Determination
'
i The inspector noted that the Department.1 Work Responsibility Checklist
-
for operations required changes to Abnormal Operating Procedure (A0P)
A0P-0042, Surveillance Test Procedure (STP) STP-302-0102, and System j
.",
Operating Procedures (S0P) S0P-0079 and SOP-0048. A review of STP-302-0102,
'Tmer Distribution System Operating Check." disclosed that Temporary Change Notices (TCN) E0-1067 and 89-105C, incorporating PMR 89-025 had
~been prope-ly accompli N d.
A0P-0042, " Loss of Instrument Bus," was changed by TCN 80-106*
' SOP-0048, "110 YAC System (Sys 304)," and S0P-0079,
" Reactor Protection System (Sys 508)" were charged by TCN 89-1065 and TCN 89-1064.
e On September 13, 1989, the inspector observed maintenance activities c.ssociated Mth the Division I emergency diesel generatnr room vertilation fan Breaker 1EOS*SWG1A-ACB12. The control building operator identified that the charning motcr was continuously running. MM ntenance Work Order Request (MW0s1 R132605 was initiated to res, tore the.
.ker to an operable condition..After removing the breaker to the electt s. shop, a spare j
breaker was assioned to IEJS*SWG1A-ACB12 and the " atilation fan started
'
to prove operabiTity. The Division I diesel gene
'nr was subsequently
.
declared operable.
'
.
_
_
.
- _ -.
-
,
E
',
i n
-
.
,
,
- .
g-8-n r
During troubleshooting of the breaker, the electrician identified that a r'.
pin in the breaker subassembly had sheared off.
The. pin normally allows
'
rotation of the cam which makes and breaks the contact for the charging motor. At of the end of the inspection period, the engineering staff was evaluating the reason for the pin failure. GE, the supplier of this 480
.
volt AKR-30 breaker, has been notified of the pin failure and will be
onsite to help evaluate the reason for the pin shearing. This evaluation will be documented in CR 89-1021.
'
No violations or deviations were identified, f-6.
Surveill_ance Test Observation (61726)
During this inspection period, the inspector reviewed the technical
adequacy of Surveillance Procedure STP-051-0201, "RPS-Main Steamline
-
Isolation Valve - closure Monthly Chfunct." This' procedure was being performed when the reactor unexpectedly scrammed. The inspector also observed surveillance activities associated with the low pressure coolant injection (LPCI) system. Each of these inspection activities is disc.,ssed
'
below:
'
"
STP-051-0201 Surveillance Test Procedures STP-204-0202, andSTP-204-0203."LPCI"B"
'
and "C" Discharge Piping Fill and Valve Lineup Verification" Surveillance Test Procedures STP-204-0202, and STP-204-0203, "LPCI
"B" and "C" Discharge Piping Fill and Valve Lineup Verification,"
i were perfonned on September 27, 1989, with the reactor at full power.
These monthly surveillance procedures satisfy the requirements of
Technical Specification (TS) Section 4.5.1.a.1 as it applies to the LPCI system and to 4.5.2.1 as it relates to 4.5.1.a.1 by verifying
!
l that the system piping, from the pump discharge valves to the system
'
L isolation valves, is filled with water by venting at the high point vents.
It also demonstrates system operability by verifying that each valve (manual, power operated, or automatic) in the LPCI.. system flow path that is not locked, sealed, or otherwise secured in position, is in its correct position. This e t..*ies TS 4.5.1.a.2 as it applies to the LPCI system. This also : 4tisfies TS 4.5.2.1 as it relates to TS 4.5.1.a.2.
'
This procedure also demonstrates system operability by verifying that each valve (manual, power operated, or automatic) in the suppression pool cooling mode of the RHR system flow path that is net lockede sealed, or otherwise secured in position, is in its correct position, j
This will satisfy TS 4.6.3.3.a.
'
The inspector accompanied an operator performing portions of the procedures in the plant.and in the control room.
It was noted that procedural precautions and limitations were followed, all
'
L
-
_
__
...
.
.
H
F.
s g
,
-
,
<
....
,
...
,
,
- t
<
,
-9-
<
prerequisites satisfied, and appropriate authorization had been granted. The inspector observed the operator exercise appropriate
'
caution when venting.the LPCI lines due to the presence of potential sources of airborne radiation and contamination. All vented fluid i
was correctly contained and routed to nearby floor drains. The test.
results were determined to be acceptable and were properly reviewed l
by the control operating foreman.
"
STP-051-0201
'
,
"RPS-Main Steamline Isolation Valve-Closure Monthly ChFunct"
'
,
On September 30, 1989, when the reactor scrammed, the licensee was j
performing STP-051-0201, "RPS-Main Steamline Isolaticn Valve-Closure
'
Monthly ChFunct " to' satisfy TS Section 4.3.1.1. Table 4.3.1.1-1.6.
- 3 This TS requires each RPS instrumentation channel be demonstrated operable by the performance of a' channel functional test.
Specifically, when in Operational Condition i, it requires a monthly
.
L channel functional test of the MSIV closure function.
'
>
To perfonn a technical: review of the procedure; the inspector l
consulted various electrical drawings.on the RPS and MSIV logic and wiring, test switch contacts, and effects on the circuitry when placed in the test position. The inspector' discussed the surveillance
-
with the individual who performed the test and independently did a
'
'
detailed " walk-down" of the: test to assure its workability. The inspector consulted with individuals in the maintenance and operations department with expertise on the sinems while reviewing, thf.: drawings.
The inspector also independently reviewed other technical' references
,
(e.g. the Licensed Operator Training Manuel) to assure a proper
understanding and evaluation of the procedure.
It was concluded that
,
the procedure was adequate to perform the surveillance test without
. inducing an unwanted condition.
Additional information on the reactor scram is contained in paragraph 3.
No violations or deviations were identified.
7.
Potential Part 21 Followu) - Maximum Combined Flow Limiter Settino and Postulated Control Valve Lailure The licensec was informed by General Electric (GE) of a potentially reportable condition involving the slow closure of a nain turbine control valve due to a postulated failure. A closure time less than 2.3 seconds will cause the reactor to scram on high neutron flux. A closure time of
'
greater than 2.3 seconds would cause a reactor scram due to-high reactor pressure (a slow increase in flux accompanies the pressure increase).
This closure time (greater than 2.3 seconds) may cause the minimum
>
critical power ratio (MCPR) safety limit to be exceeded if the maximum combined flow limiter (MCFL) is set for less than 113 percent of rated steam f, low.
Because of the delay in reactor scram until the high pressure
.
-
- -
- -
-.
. _.
_.
.
,
_.
~.,
,
l.
,
>
.
~
i
,
-10-o
,
setpoint is reached, a large increase in the surface heat flux of the fuel rods would cause a chango in the critical power ratio (CPR).
'
The purpose of the MCFL is to prevent an excessive total steam flow (i.e.,
the com)ined flow to the turbine through the control valves and.to the
'
-
condenser through the condenser bypass valves) in the event of a failure
,
[.
in the pressure regulating circuitry (i.e., an upscale failure of the
'
demand signal due to the pressure regulator failing open). This is an
,
important feature on plants with a large bypass (steam dump to condenser)
e capacity. The RBS capacity is a nominal 10 percent, a relatively small capacity. The licensee reviewed startup test data and operating records and detennined that the MCFL had been normally set at 109 or.110 percent.
J GE calculation for the generic BWR-6 and this MCFL setting with an assumed
!
MCPR limit of 1.18, shows that the MCPR safety limit would be exceeded by 0.02 during the postulated event.
A licensee review of plant operating records disclosed the MCPR operating
,,
limit margin has always been greater than 0.02; the smallest margin occurred recently (September 9,1989) and was 0.0377. The licensee concludes from this that, had the postulated event occurred, the resulting transient would not have caused the limit to be exceeded. The licensee
' anticipates that RBS' specific analyses in progress will disclose a margin
' '
of safety greater than that currently calculated. This analysis is to be complete by the end of December 1989.
On September 1,1989, licensee management issued Standing Order 82 to the operators. ' This order described the event, parametric responses to the'
event, and irr 11 ate operato. actions to enhance the margin to the operating limit in the event of single turbine control valve closure without immediate unit trip. These actions included utilizing recirculation flow control to reduce reactor power to 80 percent,
,
verifying that the bypass valves are closed, contacting Reactor Engineering l
L to determine the necessity of reducing the rod line, and other nonimmediate i
actions. Also, for additional conservatism, the maximum fraction of limiting CPR (MFLCPR) was reduced from 1.00 to 0.98.
The inspector
- ,
I routinely verified, through control room log entries and observation of l
the process computer P-1 printout, that the unit was operated within the bounds of this parameter.
I'
During a recent forced outage (September 29-30,1989), the licensee reset
the MCFL setting to the GE recommended setting of 115 percent.
l This setting was verified by the inspector.
The MCFL was not adjusted l
prior to this because the control had behaved erratically 1. the past. By adjusting the control during the shutdown, the potcntial fur inadvertently inducing a transient during operation with a possible unit trip was avoided (theMCFLmayhavecausedthecontrolvalvestoclose).
1'
No violations or deviations were identified.
'
Hi f
YU
,
.
..,.,.
.
- - - -
fir ;; g
-
^
-
~
'
e
-
,
.
,
n
.
,
's
. e
.
,
r
!
'
'
,
-11-l
,
,
l.
r
t- -
.
8.
Exit Interview,
,
An exit interview was conducted with licensee representatives identified
.v in paragraph 1 on October 13, 1989.- During this interview, the NRC
"
inspectors reviewed the scope and findings of the report. The licensee
,
did not identify as proprietary any information provided to, or reviewed by, the inspectors,
'
r
{.
t
!
i
>
!
!
!
,
1'
t, L
1-
..
,
!
,
l
,
1'
I
,
-
-