ML20198H791
| ML20198H791 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 09/11/1997 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20198H783 | List: |
| References | |
| 50-327-97-13, 50-328-97-13, NUDOCS 9709220190 | |
| Download: ML20198H791 (12) | |
See also: IR 05000327/1997013
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U.S. NUCLEAR REGULATORY COMMISSION
REGION 11
Docket Nos:
50-327. 50 328
License Nos:
Report Nos:
50-327/97-13, 50-328/97-13
Licensee:
Tennessee Valley Authority (TVA)
Facility:
Sequoyah Nuclear Plant, Units 1 and 2
Location:
Sequoyah Access Road
Hamilton County, TN 37379
Dates:
July 25 through September 4.1997
Inspectors:
M. Shannon. Senior Resident Inspector
D. Seymour, Resident Inspector
D. Starkey. Resident Inspector
Approved by:
M. Lesser. Chief
Projects Branch 6
Division of Reactor Projects
Enclosure
9709220190 970911
ADOCK 05000327
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EXECUTIVE SUMMARY
Sequoyah Nuclear Plant, Units 1 and 2
NRC Inspection Report 50-327/97-13, 50-328/97-13
This special inspection was conducted to review the events associated with the
misalignment of the #5 vital battery (spare) to the #4 vital battery board on
July 24,1997.
During the safety system raalignment, a senior reactor
operator (SRO) and an assistant unit operator (AUO) failed to properly perform
procedural steps which resulted in not properly aligning the battery to the
vital battery board. This resulted in the failure to meet the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />
technical specification (TS) action statement for returning the battery bank
to operable status. The battery bank is common to both units and was
inoperable for approximately 30.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.
An apparent violation was identified for failure to meet the limiting
condition for operation (LCO) action statement of TS 3.8.2.3.b. in that
the DC vital battery channel was inoperable for approximately 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />
which exceeded the TS LC0 action statement for restoring the inoperable
battery within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or be in Hot Standby within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> (EEI 50-327,
328/97-13-03).
An apparent violation of TS 6.8.1 was identified with two examples of
not following procedures in that an operator (SRO) failed to close the
correct circuit breaker, and did not stop an evolution when unexpected
conditions were encountered (EEI 50-327, 328/97-13-01).
An apparent violation of 10 CFR 50 Appendix B Criterion V was identified
for the failure to ensure independent verification as appropriate to
circumstances while realigning the spare #5 vital battery to the #4
vital battery board.
Additional examples were identified by the
inspectors of failure to follow and/or inadequate procedures regarding
AU0 rounds (EEI 50-327, 328/97-13-02).
An apparent violation of 10 CFR 50 Appendix B Criterion XVI was
identified for failure to promptly identify an adverse condition (missed
out-of-tolerance battery voltage reading) (EEI 50-327. 328/97-13-04).
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Control room operators initially performing the battery realignment, and
subsequent oncoming crews, did not identify the lack of an expected main
control room alarm,
in addition, the procedure did not highlight that a
main control board alarm was expected when realigning the spare battery.
Poor AU0 rounds practices vere identified, based on the length of time
taken to perform AUO rounds.
Based on the examples identified in this
inspection, and previous examples, the inspectors concluded that AUO
rounds and procedures are a significant weakness.
Poor rounds taking practices that contributed to the duration of event
were not addressed by the licensee, which is considered a weakness in
the event investigation.
A negative observation was noted when operators logged entry into the
wrong TS action statement when realigning the vital batteries on
July 24.
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Reoort Details
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Inoperable Vital 125 Volt DC Battery
A.
Insoection Scone (71707)
The inspectors reviewed the events related to the failure of an SRO to
properly realign the spare #5 vital battery to the #4 vital battery
board while hanging a clearance on the #4125 volt DC vital battery.
B.
Event Synoosis
At 6:13 a.m., on July 24,1997, the #4125 volt DC vital battery was
removed from service in order to perform maintenance on the battery.
At
11:00 a.m. , on July 25, 1997, a training instructor with operator
trainees discovered that the supply breaker (breaker #107) from the
spare battery to the #4 vital DC board was open. At 11:33 a.m., breaker
- 107 was closed and at 12:36 p.m., following surveillance activities,
the spare battery and the #4 vital DC board were declared operable.
The
licensee initially briefed the inspectors of the adverse system lineup
at approximately 11:50 a.m. , on July 25.
C,
Observations and Findinas
During the review, the-inspectors determined that an AVO initially
requested assistance from an SR0 in the use of procedure 0-S0 250-1, 125
Volt DC Vital-Power System, to realign the spare #5 vital battery to the
- 4 vital battery board and to remove the #4 vital battery for
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maintenance. The licensee-determined that SR0 assistance was requested
~by the AU0 due to uncertainty in performing the-procedure. Step 8.4.8
of procedure 0-S0-250-1 required the operator to close the spare battery
feeder breaker (#107) from vital battery #5 which would provide the
vital battery supply to vital ~ battery DC board #4 while the normal #4
vital battery _was undergoing preventive maintenance.
The operator
failed to close the correct breaker and in fact checked closed a
different breaker identified as #107. This is identified as one example
of an apparent violation for failure to follow procedure (EEI 50-
327,328/97-13-01).
The procedure step specifically stated " Place Distribution Panel A-S or
B-S breaker in ON position to align feed to desired Vital Battery Board.
(N/A others) (Located on wall outside Vital Battery Board Rooms. AB el
734')." A short table followed this step which contained the heading,
" Desired Battery BD Feeder From Distr Panel." The table included the
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step "125V dc Vital Battery Board IV, Feeder - BKR 107." This step was
signed off as having been completed on the morning of July 24.
The
inspectors considered the procedural step to be confusing in that it did
not consistently identify the exact panel nomenclature.
Later in the
procedure, step 8.4.24 required the operator to open the normal supply
breaker from the #4 vital battery to the #4 vital battery board. This
breaker is also identified as BKR 107.
The step does not uniquely
identify the breaker with the #4 vital battery and vital board, since it
is generically written to apply to 1 of 4 DC channels and 1 of 4 circuit
breakers identified as BKR 107.
During a subsequent review, the licensee noted that five vital board 125
volt DC breakers on different boards were labeled as #107.
The breakers
were located in adjacent vital battery board rooms and the licensee's
investigation noted that the operator had gone to the wrong room and had
verified the wrong breaker as " closed" on the morning of July 24.
Although 0-50-250-1 contained enough information to correctly align the
batteries, and the panels and breakers were sufficiently labeled, the
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inspectors concluded that the procedure did not uniquely and
consistently identify which specific breaker at which specific panel was
to be operated.
This, coupled with several breakers with the same
nomenclature, provided a confusing and unclear procedure.
This is also
supported by the fact that the AU0 requested assistance from an SR0 in
the performance of the procedure.
A.lthough the operator was required to " Place Distribution Panel A-S or
B-S breaker in ON position to align feed to desired Vital Battery Board"
(a key step in the alignment of the #5 vital battery to the #4 vital
battery board), the SRO went to the wrong distribution panel and found a
different BKR 107 already closed (the SR0 was looking at the normal
supply breaker for the #4 vital battery to the #4 vital battery board,
which is also labeled BKR 107).
The SR0 failed to notify the control
room of the potential status control issue and continued on with the
evolution.
The licensee determined that the SR0 did question the
unexpected breaker status, but then inappropriately verified that the
similarly labeled breakers in the other vital battery board rooms were
also closed.
In addition, the licensee's investigation revealed that after the SRO
initially verified that the #107 breaker (normal supply) was closed,
several steps later in the procedure, he opened the same breaker,
removing the #4 Vital Battery from the #4 Vital Battery Board.
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This failure to evaluate an unexpected as-found condition was similar to
an event noted in Inspection Report 97 03, where an operator found a
valve in an unexpected position and did not notify the control room,
resulting in the spent fuel pool cooling system being misaligned and the
spent fuel pool cooling pump being dead headed for about two hours.
Site Standard Practice (SSP) 2,51. Rules of Procedure Use, Section 3.3,G
and Section 3.3.H requires the operator to "Stop the procedure if an
unexpected response is obtained.
Notify the SOS /SR0 designee or
Cognizant Supervisor, and the SOS /ASOS or Cognizant Supervisor will
evaluate the situation and document the review and approval to continue
the procedure, if applicable, in a note."
In this case, when the SRO
encountered the unexpected breaker position, he did not stop the
manipulations in the procedure and did not inform the 50S/SR0 designee
or a cognizant cupervisor of the deficiency. Therefore the SOS /SR0
designee or cognizant supervisor did not have the opportunity to
evaluate the as-found condition and to authorize resumption of the
manipulations.
The licensee determined that the SRO considered himself
the cognizant supervisor. The failure to adhere to SSP-2.51, when
unexpected conditions were encountered, is considered to be a second
example of an apparent violation for failure to follow procedures (EEI
50-327, 328/97-13 01).
During the subsequent review, the licensee and the inspector noted that
Step 8.4.8 of procedure 0-S0-250-1 did not require independent
verification, although independent verification is required by Site
Standard Practice,-(SSP),12.6, Equipment Status Verification and
Checking Program, Revision 9, when realigning safety related systems,
Failure to ensure independent verification steps were appropriately
prescribed as delineated by SSP-12.6 is considered to be an apparent
violation (EEI 50-327, 328/97-13-02), and contributed to the licensee's
failure to identify the misaligned spare #5 vital battery.
The licensee noted an additional 0-50-250-1 procedure weakness. The
procedure did not identify or contain a note to the operators alerting
them that, when the #5 battery was placed in service, the main control
board alarm "#5 Battery In Service" would alarm / actuate. The lack of
this. alarm to be in the alarmed state should have alerted the control
room operators that the spare battery was not properly aligned to the
vital DC board, This procedural weakness contributed to the operating
crew's failure to identify the misaligned spare battery.
In addition,
the-inspectors concluded that the control room operators initially
performing the battery realignment, and subsequent cncoming crews, did
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not question the lack of an expected main control room alarm and thus
missed opportunities to identify the inoperability.
The licensee's review also noted that, on July 24, during the initial
system alignment, the unit SR0 entered an inappropriate TS action
statement, when he logged that the plant was in TS 3.8.2.1.
This TS
action provided an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> LCO action statement.
However, the unit w6s
actually in TS 3.8.2.3 which provided only a 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> action statement.
The procedure was completed, albeit incorrectly, within the 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
The inspectors noted, once the breaker misalignment was discovered on
July 25, the correct action statement (TS 3.8.2,3) was entered and met.
The licensee and the inspectors determined that, with the distribution
panel breaker in the wrong position, the licensee had not been in
compliance with Technical Specification (TS) 3.8.2.3.b DC Distribution,
which requires that each of the four DC vital battery channels be
The TS further requires that a deenergized vital battery bank
be restored to an operable condition and in an energized status within
2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or be in at least hot standby within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
Following the misalignment of the DC system on the morning of July 24,
the #4 DC vital battery was inoperable from 6:13 a.m., on July 24 until
12:36 p.m. , on July 25, 1997, an approximately 30.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> time frame,
The failure to meet the requirements of TS 3.8.2.3.b is considereu to be
an apparent violation (EEI 50-327,328/97-13-03).
The licensee noted a contributing cause for this event was an
insufficient unique identification nomenclature for the components in
the 125 VDC System.
The licensee also noted that the plant 120 VAC
Vital boards. 250 VDC non-Vital boards, and 125 VDC Vital boards, had
examples where components lacked unique identifiers.
At the end of the
inspection period, the licensee identified that approximately 749 plant
breakers lacked unique identification tags.
The inspectors determined
that components can be adequately identified using the component
nomenclature in conjunction with the specific distribution board.
However, coupled with an unclear procedure and poor self-checking
techniques, the correct component to be operated was not identified.
The licensee's review documented in PER No. SQ971762PER, noted a similar
event documented by LER 50-327/95 08.
In this PER, the licensee stated
that corrective actions from the previous event would not have prevented
the July 24, 1997 event. The inspectors noted that LER 95-08 documented
a reactor trip as a result of an operator opening a wrong breaker. The
operator had opened breaker #48 on the wrong vital 120 VAC board. All
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four 120 VAC vital boards had breakers labeled #48. The cause of the
event was attributed to inadequate self-checking.
The inspectors
concluded that the June 1995 event was similar to the July 24, 1997
event. The lack of unique equipment identifiers was not recognized as
an issue in the earlier event.
Subsequently, the licensee identified various corrective actions, which
included:
revising the operating procedure to require independent
verification, hanging caution tags on the five #107 breakers to ensure
proper identification, plans to relabel all -125, and 250 volt DC and 120
volt AC boards, developing jcb performance measures for sparing out the
125 volt DC batteries, revising the battery procedure to identify the #5
battery in-service alarm, including the appropriate TS action statt. ment
in the battery procedure, reviewing other operations, maintenance and-
chemistry procedures to ensure proper independent verifications have
been identified, and taking disciplinary actions for the two operators.
During a subsequent review of the July 24 event, the inspectors were
concerned with the apparent failure to identify the misaligned breaker
during AVO tours / rounds of the control building area. The AVO rounds
include voltage readings on the #5 vital battery.
The AVO tour that was
in question was performed approximately 19 hours2.199074e-4 days <br />0.00528 hours <br />3.141534e-5 weeks <br />7.2295e-6 months <br /> after the #5 vital
battery was disconnected. The #5 vital battery voltage data point was
logged as normal, although the battery voltage was most likely below the
administrative limit of 132 VDC listed in the AU0 rounds.
Around 11:00
a.m., on July 25, the #5 vital battery voltage was found to be at 128
VDC due to not being on float charge (TS required minimum of 129 volts.
AUO roundsheet administrative minimum of 132 volts), The licensee
subsequently performed a test on the spare #5 vital battery which
confirmed that at 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> into the test the battery voltage had
dropped to 131.5 volts.
Although the AVO rounds would not have
prevented the event, they should have identified the adverse condition
many hcurs sooner (12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />). The failure to promptly identify an
adverse condition (the out of-tolerance battery voltage reading) is
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considered to be an apparent violatior (EEI 50-327, 328/97-13-04).
Initial NRC review of the applicable AU0 tour noted that 52 items were
-signed off in the logs on various levels of the control building in
less than 7 minutes. The inspectors noted that many line items had
multiple items that had to be checked to determine acceptable / normal
operation and that only a cursory review of the area and equipment could
be made based on the documented AUO roundsheet.
It also appeared to the
inspectors that the duration of the AUO tour would not be reasonable
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based on the number of activities performed. This is considered to be a
poor rounds taking practice.
The licensee had not addressed this area
which is considered to be a weakness in their event investigation.
The inspectors conducted a more detailed review of a section of the AUO
control building logs, and noted the following discrepancies:
The AUO control building rounds for the mid-watch on July 25 noted
three of four battery room temperatures above 80 degrees (86, 82
and 82 degrees) with no further comments. Although the minimum
and maximum tolerances were listed as 60 and 104 degrees, the
special instructions for this itea stated, "If temperature cannot
be maintained within the nominal range (70-80 degrees), then
notify Unit Supervisor and initiate corrective action as
appropriate." There was no evidence that the unit supervisor had
been notified or of any corrective actions that were implemented.
AUO control building rounds item #41 required the operator to
verify the #5 battery voltage between 132-149 volts, however, the
maximum acceptable voltage per the system operating procedure with
the #5 battery tied to one of the vital DC boards was 140 volts.
The unique equipment identifiers listed for the 480 volt Reactor
MOV Boards were inaccurate (for example, 1-BDC-201-GG-A versus
actual 1-BCTD-201-GG).
The inspectors consider the above examples of failure to follow
procedures and inadequate procedures to be additional examples of
apparent violation EEI 50-327,328/97-13-02.
Recent NRC inspection reports have documented problems with AUO rounds
and procedures.
IR 327,328/97-01 documented a weakness for not
obtaining routine log readings during EDG operation and for not actively
monitoring the EDG, although the EDG was being operated at 110% load and
was in alarm for high exhaust differential temperature and high governor
actuator differential.
IR 327,328/96-17 identified a weakness in that
neither operations nor engineering identified that the main steam lines
and main steam drain lines were vibrating excessively and the main steam
drain line supports were broken.
IR 327,328/96-13 identified a weakness
in that the licensee failed to identify the malfunctioning steam dump
drain tank level switch, causing the steam dump lines to not drain
properly.
The operator rounds sheet lacked adequate guidance regarding
the steam dump drain tank level controls.
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In addition, that IR identified an additional weakness in that the AU0s
failed to identify the damaged piping supports following the reactor
trip (8.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> later), although required to monitor the steam dump
valves once per shift, in addition to normal roving tours of the
building.
Finally, a lack of clear guidance in operator rounds
regarding EDG starting air pressure was observed in
IR 327,328/96-09.
The licensee recently implemented the use of electronic hand held logs
for the AU0s.
However, based on the above examples AU0 rounds and
procedures are considered to be a significant weakness.
D.
Conclusions
An apparent violation was identified for failure to meet the required
action statement of TS 3.8.2.3 b in that the DC vital battery channel
was inoperable for approximately 30.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> which exceeded the TS LC0
action statement for restoring the inoperable battery within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or
be in Hot Standby within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> (EEI 50-327,328/97-13-03),
An apparent violation was identified with two examples of not following
procedures in that an operator (SRO) failed to close the correct circuit
breaker, and did not stop an evolution when unexpected conditions were
encountered (EEI 50-327,328/97-13-01).
An apparent violation was identified for the failure to prescribe
independent verification while realigning the spare #5 vital battery to
the #4 vital battery board. Additional examples were identified by the
inspectors of failure to follow and/or inadequate procedures regarding
AU0 rounds (EEI 50-327, 328/97-13-02)
An apparent violation was identified for failure to promptly identify an
adverse condition, related to a missed out-of-tolerance reading for the
- 5 vital battery (EEI 50-327, 328/97-13-04).
Control room operators initially performing the battery realignment, and
subsequent oncoming crews, did not question the lack of an expected main
control room alarm and thus missed opportunities to identify the
condition.
In addition, the procedure did not highlight that a main
control board alarm was expected when realigning the spare battery.
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Poor _ AVO rounds taking practices were identified, based on the length of
time taken to-perform AVO watchstanding duties.
Based on the examples
identified in this inspection and previous examples, the inspectors
concluded that AUG rounds and, procedures are a sigriificant weakness.
The licensee did not address poor rounds taking practices during their
event investigation which is a weakness in the licensee's event
investigation.
A negative observation was noted when operators logged entry into the
wrong TS action statement when realigning the vital batteries on
July 24, 1997,
II. Exit Meeting Summary
The inspectors presented the inspection =results to members of licensee
management at the conclusion of the inspection on September 4,1997.
The licensee acknowledged the findings presented.
The inspectors asked the licensee whether any materials would be
considered proprietary.
No proprietary information was identified.
PARTIAL LIST OF PERSONS CONTACTED
Licensee
- Bajestani, M., Site Vice President
- Butterworth H , Operations Manager
- Koehl, D., Assistant Plant Manager
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- Reynolds, J. , Operations Superintendent
- Salas, P., Manager of Licensing and Industry Affairs
EC
- Lesser: M.,-Chief. Division of Reactor Projects Branch 6
Seymour, D., Resident Inspector
- Shannon, M., Senior Resident Inspector
- Starkey, D., Resident Inspector
- Attended exit interview
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INSPECTION PROCEDURES USED
IP 40500:
Effectiveness of Licensee Controls In Icntifying, Resolving, &-
Preventing Problems
IP 7170/:
Plant Operations
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ITEMS OPENED
Iype Item Number
Status
Descrintion and Reference
50-327, 328/97-13 01
Open
Two Examples of Failure to follow a
Procedure (Section C)
50-327, 328/97 13-02
Open
Failure to Perform Independent
Verification, and Failure to
Properly Perform AVO Rounds
(Section C)
50-327, 328/97-13-03
Open
Failure to Meet The TS LCO Action
Requirements Of TS 3,8,2.3,b For
Vital Battery Bank Operability
(Section C)
50-327, 328/97-13 04
Open
Failure to Promptly Identify an
Adverse Condition (Section C)
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