ML17056B895
| ML17056B895 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 06/02/1992 |
| From: | Hodges M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Sylvia B NIAGARA MOHAWK POWER CORP. |
| References | |
| NUDOCS 9206090023 | |
| Download: ML17056B895 (16) | |
See also: IR 05000410/1992081
Text
Docket No.
50-410
Mr. B. Ralph Sylvia
Executive Vice President - Nuclear
Niagara Mohawk Power Corporation
¹ine MilePoint
Post Office Box 63, Lake Road
Lycoming, New York 13093
Dear Mr. Sylvia:
Subject:
RESPONSE TO THE NRC REGION I AUGMENTEDINSPECTION TEAM
(AIT) REVIEW OF THE MARCH 23, 1992 NINE MILEPOINT UNIT 2
LOSS OF OFFSITE POWER AND CONTROL ROOM ANI'AJNCIATOR
EVENT, INSPECTION REPORT NO. 50-410/92-81
This refers to your letter dated May 13, 1992, which responded to the AITreport transmitted
to you on April 10, 1992.
Your letter presented
a summary of Niagara Mohawk's corrective
actions relative to the March 23, 1992 event and the findings of the subsequent AIT. You
described the corrective actions that had been accomplished,
and those not yet finished were
assigned specific completion dates.
These actions willbe examined during a future inspection
of your facility
Your cooperation with us is appreciated.
Sincerely,
Marvin W. Hodges, Director
Division of Reactor Safety
920b090023
920b02
ADOCK 05000410
Q
ME~ l
lI
B. Ralph Sylvia
JUN 03 1992
2
cc w/encl:
J. Firlit, Vice President - Nuclear Generation
C. Terry, Vice President - Nuclear Engineering
J. Perry, Vice President - Quality Assurance
S. Wilczek, Jr., Vice President - Nuclear Support
K. Dahlberg, Unit 1 Plant Man'ger
M. McCormick, Unit 2 Plant hLu~er
D. Greene, Manager, Licensing
J. Warden, New York Consumer Protection Branch
G. Wilson, Senior Attorney
M. Wetterhahn, Winston and Strawn
Director, Power Division, 'Department of Public Service, State of New York
C. Donaldson, Esquire, Assistant Attorney General, New York Department of Law
K. Abraham, PAO AllInspection Reports
Public Document Room (PDR)
Local Public Document Room (LPDR)
Nuclear Safety Information Center (NSIC)
NRC Resident Inspector
State of New York, SLO Designee
bcc w/encl:
Region I Docket Room (with concurrences)
W. Lanning, DRS
C. Cowgill, DRP
J. Yerokun, DRP
L. Nicholson, DRP
S. Greenlee, DRP
W. Schmidt, SRI - Nine Mile
R. Lobel, OEDO
R. Capra, NRR
J. Menning, NRR
D. Brinkman, NRR
RI:DRS
5/8/92
~c/q
Anderson
98/%92
RI:DRS
Hod
s
6/p /92
OFFICIALRECORD COPY
A:9281.RL
V NIAGARA,
u MOHAWK
NIAGARA~OH +KPOKIER CORPORATION/NINE MILEPOINT. PO BOX 63. LYCOMING,NY 13093/TELEPHQNE {315) 349.288/
8. Ralph Sylvia
May 13, 1992
Executive Vice President
NMP84888
Nuclear
Mr. Marvin W. Hodges
Director, Division of Reactor Safety
United States Nuclear Regulatory Commission
475 Allendale Road
King of Prussia,
PA 19406-1415
RE:
Nine Mile Point Unit 2
Docket No. 50-410
NPF-
Subject:
Response
to the NRC Region I Augmented Inspection Team (AIT) Review of the
March 23, 1992 Nine Mile Point Unit 2 Loss of Offsite Power and Control Room
Annunciator Event.'Inspection Report No. 50%10/92-81
Dear Mr. Hodges:
On March 23, 1992 Nine Mile Point Unit 2 (NMP2) declared an "ALERT," in accordance with
~
~
~
its Emergency Plan criteria, as a result of the loss of all Control Room annunciators.
The loss
of Control Room annunciators was due to the unplanned loss of offsite '1 15 KV power line No.
5, associated
Reserve Transformer 1A, and related Division I loads as a result of an inadvertent
actuation, during restoration from calibration, of an overcurrent protection relay. At the time
of this event, NMP2 was in the Second
Refuel Outage,
and the reactor core was partially
offloaded.
Fuel movements
were not in progress
at the time of the event.
A detailed
description of the sequence
of events is contained in LER 50-410/92-06, dated April 22, 1992.
In response to this event, the NRC formed an Augmented Inspection Team (AIT) on March 24,
1992.
During the period of March 24-28, 1992 the,AIT conducted an independent inspection,
review, and evaluation of, the conditions and circumstances
associated
with this event.
The
AIT had complete access to plant staff and records to support their investigation.
Niagara
Mohawk cooperated'ully with the AIT.
The AIT's inspection report, 50-410/92-81,
was
received by Niagara Mohawk on April 13, 1992.
Niagara Mohawk was requested to respond
to this report within 30 days of receipt, discussing our plan for corrective actions.
This letter summarizes Niagara Mohawk's corrective actions relative to the NRC's findings in
Inspection Report 50-410/92-81.
This letter also includes the corrective actions identified in
LER 50-410/92-06, dated April 22, 1992 and Niagara Mohawk's presentation at the AIT exit
meeting on April 1, 1992.
A complete listing of all corrective actions is=contained. in the
Niagara Mohawk assessment
team report.
TEAM
Immediately following termination of the ALERT, an NMPC assessment
team was formed under
the direction of the Nine Mile Point Unit 2 Plant Manager, to investigate
and evaluate the
circumstances
leading to the declaration of the ALERT, and to evaluate the performance of
equipment and personnel.
A written report, consisting of individual team reports and corrective
actions has been prepared.
Corrective actions have been established for all identified concerns
i
1
Mr. Marvin W. Hodges
May 13,,1992
and will be ti'acked to conclusion
via the Deviation/Event
Report
(DER) process.
The
assessment
report has been reviewed by the Station Operations Review Committee.
A copy
of the assessment
report will be provided to the Senior Resident Inspector at Nine Mile Point.
W R
PRI RITIZATI
ND
HED L N
Correcting the deficiency that prevented UPS-1A from transferring back to the normal power
source from the maintenance
power supply was not given the proper priority by Operations,
Outage IVlanagement, Work Control or System Engineering.
This lack of timeliness allowed the
deficiency to remain uncorrected for 15 days, during which time the plant was vulnerable to
a loss of UPS-1A loads (Control Room annunciator local power supplies) through loss of the
maintenance
power supply.
The root cause
of the failure to properly prioritize this work was that Operations
did not
~
exercise their responsibility for setting work priority and tracking work. Contributing factors
were:
the procedure requires that Work Requests
(WRs) be sent to the Operations
Planning
group (part of the Work Control Center) rather than to Operations
Department
personnel,
responsible
personnel
may have
been distracted
by multiple outage
priorities early in the
outage,
and the potential for the loss of all Control Room annunciators
upon loss of a single
UPS (in this case, UPS-1A) was not widely understood.
Corrective actions are:
Administrative Procedure
(AP) 5.5
~ 1, "Work Requests" willbe revised to clearly require
the Station Shift Supervisor (SSS)/Assistant
SSS establish WR priority. This will be
completed by September
1992.
In the interim, WRs are sent to the Control Room to
establish priority.
A Lessons
Learned Transmittal (LLT) will be sent to all Operations, Work Control and
Technical
Support
personnel
to remind them that Operations
personnel
have the
responsibility to establish work priorities commensurate with the importance to station
operations.
This will be completed by June 1992.
Operations has included the UPS's on a Control Room status board.
Operations is developing a list of important equipment to be included in the daily work
schedule.
This will be completed by September
1992.
A Lessons Learned Transmittal (LLT) will be sent to all NMP2 personnel to stress the
urgency of corrective maintenance
on UPS's,
until the full capability of the UPS is
restored.
This will be completed by June 1992.
Regarding maintenance work control, NMP2 had begun implementing improvements following
NMPl's inadvertent Loss of the Ultimate Heat Sink event of February 1992.
Work packages
were prescreened,
and plant impact was assessed.
However, the plant impact assessment
part
of the overcurrent protection relay work package was inadequate
in that it did not address the
impact of inadvertent relay actuation during the work. Interviews with Control Room super-
vision, Outage Management, Operations Management, and the technicians performing the work
Mr Qarvin W. Hodges
May 13, 1992
onsidered the risk of tripping line No. 5 d
these relays.
This could occur during'calibration when the cover is re-installed on the relay.
following the March 23, 1992 event, all relay work was stopped at NMP2, and plant impact
statements
in relay work packages
were re-assessed
and clarified before allowing work to
continue.
Direction was given by the NMP1 and NMP2 Plant Managers, via memo to Branch
Managers onsite, reinforcing expectations for pre-work job planning of Relay and Control Work
In Progress
(WIP) data, sheets as outlined in Site Administrative Procedure AP-5.2.5, "Work In
Progress."
R LT
I NA D
P
Relay and Control technician job performance leading up to and during the event was not up
to expectations..The
technicians did not have a full understanding of the potential equipment
and plant impact.
Once the inadvertent relay actuation
and line loss had occurred,
the
technicians did acknowledge the error to the Control Room. However, subsequent
evaluation
and communication to the Assistant SSS regarding the use of line No. 6 to reenergize the line
No. 5'bus was inadequate,
resulting in the further loss of line No. 6.
As the AITreport notes,
a human factors issue contributed to the inadvertent relay actuation.
The relay that actuated when the, cover was replaced
is located only inches from the floor,
making cover replacement difficult. The technicians
had not been trained in this particular
configuration.
To address the noted performance deficiencies,
Relay and Control supervision instructed
all
Relay
and
Control technicians
at NMP2 that complete
and
concise
equipment
impact
statements
must be included on the WIP data sheets and that they must provide Operations
with a full functional description of the protective relay or metering logic pertaining to the
system under test.
Improved pre-job briefings will be conducted
and will include sufficient
detail to establish
a full understanding
by all personnel involved in the particular test of the
circuit functions,
including
all auxiliary relays
associated
with the scheme
under test.
Additionally, a training mockup has been developed to certify Relay and Control personnel for
removal/re-installation of relay covers.
A training effectiveness evaluation was conducted by the Operations Training Department to
review and identify operator strengths and weaknesses
resulting from this event. This review
resulted in the nyy{fificationof existing, and the development of new Requalification Lesson
Plans to upgradCIeensed
and non-licensed operator training programs.
The plans include but
are not limited ti7.~
~
The review of the auxiliary boiler relay protection logic and how it affects offsite power
availability.
~
Plant impacts upon loss of individual UPS loads.
~
A technical seminar by the Relay and Control Department on line protection schemes
and relaying.
~
Additionally, simulator evaluations identified that a reproduction of'a similar loss of line No. 5
scenario was not possible.. A Simulator Discrepancy
Report was generated
to correct the
deficiency and completed on April 3, 1992.
- Page 4
tVlr. Marvin W. Hodges
lUlay 13, 1992
op
o
g
t will discuss the miscommunication
aspects
of the M
h 23,
Op
o
personnel,
and develop guidelines for a moie assertive
and
type of communcation between Operations and Support personnel, including Relay and Control
personnel.
These actions will be completed prior to Unit 2'startup from its Second
Refuel
Outage.
Additionally, to aid operators
in correcting alarm conditions resulting from tripped relays,
Operating Procedure
N2-0P-70, "Station Electrical Feed
and 115 KV Switchyard," will be
revised to include protective devices relaying schemes.
The procedure will be revised prior to
Unit 2 startup from its Second Refuel Outage.
WEA NE
E
INMANA EME
PP
T
F
T N
The AIT report addresses
three weaknesses
in management
support of Operations.
The first
is acceptance
of delays in operation of offsite power supply breakers inherent with the use of
, a traveling operator.
In order to minimize this delay, plant operators will be trained to identify
"targets" of tripped devices in the Scriba switchyard, and to communicate this information to
Power Control.
Depending
on the cause for the tripped condition, Power Control will then
remotely operate switchyard equipment to re-energize lines. This training willbe conducted by
December 1992.
The second
weakness
concerned the absence
of a backup air supply during the refue/ing
outage, with air pressure being used in reactor vessel and main steam line'seals.
These seals
have multiple methods of sealing: mechanical as well as an inflatable seal.
Thus, no backup
air supply is needed.
However, Niagara Mohawk had planned to and willassess
the need for
a backup air supply for the Third Refuel Outage for normal maintenance
reasons.
The third weakness,was
acceptance
of cumbersome,
generic
procedures
which require
operators to use, concurrently, several procedures
during a loss of offsite power.
Niagara
Mohawk will be writing new procedures for "Station Blackout." Atthat time, we will review
operating
procedures
to determine if improvements
can
be made.
This will be done by
December 1992.
Due to inadequate
design 'of the Service Water cooling pressure
detection logic, two new
scenarios. have44M-identified that would have the Division III Emergency Diesel Generator
running for a tetjraurveillance, or as a result of a iow reactor water "level two" initiation, with
either situati~'CSSowed
by a sequential
The cooling water to the
Division IIIDiesel Generator would isolate in either scenario.
This would render the Division III
Diesel Generator unavailable for accident mitigation, due to high temperature damage; without
operator action to return service water cooling.
To correct this, a modification will be imp'lemented during the Second
Refuel Outage that
addresses
the scenarios
identified above to prevent the loss of Division III Diesel Generator
during a sequential
This modification will install a time delay for the
service water cooling supply valves to close the valves after receipt of a low pressure signal
on the service water supply header.
This will provide sufficient time for the service water
system to re-establish proper pressure; after power is restored, following loss of divisional or
~
.
Mr. Marvin W. Hodges
May 13, 1992
offsite power. The present time delay, which permitted closing Service Water valves after one
r'ninute of diesel operation, will be disconnected.
Additionally, administrative controls have been established in N2-OP-100B, "High Pressure Core
Spray Diesel Generator," such that during periods when Division I or II Diesel Generators
are
out of service, Division III switchgear will be aligned to an offsite power source protected by
the operable Division I or Division II Diesel Generator.
Niagara Mohawk's assessment,
the significance of design deficiencies identified, and corrective
actions will be reported in a supplement to LER 50-410/92-06.
The expected submittal date
is June 15, 1992.
NTR L
PLIE AND P-
Engineering's evaluation showed that the loss of Control Room annunciation was consistent
with the design.
Presently, ten power supplies are provided to supply the annunciator load for
the NSSS panel.
A minimum of five power supplies are required to,carry the full load (two
125/24/12/VDC power supplies, two 125VDC power supplies, and one 12VDC power supply).
The remaining five provide 100% backup.
However, the majority of the 125VDC power
supplies are fed from UPS-1B. Therefore, a loss of UPS-1B power feed would cause the loss
of all NSSS Plant Monitoring System computer inputs.
All of the 12VDC and 24VDC power
supplies are fed from UPS-1A so loss of this UPS power feed would totally disable the NSSS
annunciator system.
Plant changes are being made which include a rearrangement of the annunciator power supplies
within the annunciator cabinets to preclude loss of all annunciation upon loss of one UPS. This
is to be done in two steps: first, a redistribution of the load in the NSSS panel; and second, an
upgrade
and/or redistribution of the load in the BOP annunciator
panel.
Engineering
has
completed the design for rearrangement
of the NSSS annunciator power supplies,
and field
installation will be completed during the Second
Refuel Outage.
Upgrading the annunciator
power supplies or redistributing the loads in the BOP annunciator panel willbe done during the
Third Refuel Outage.
UPS-1A was out of service on March 23, 1992 due to the UPS being on its maintenance power
supply. Corrective maintenance determined that one of the six sets of internal batteries in the
UPS were degraded which prevented the Unit from being returned to normal service.
The
design life of t~hatteries is 18 months (recently increased from 12 months), but they only
lasted about 7~s in service.
This premature failure is being evaluated at an independent
laboratory.
SubCefaent to a design modification made
in 1991, the batteries
were only
required for startup of the Unit. A design change to eliminate dependence
on the batteries has
been completed and willbe installed in the Second Refuel Outage.
Increased
UPS reliability is
possible through the implementation of this design change.
NMP2 had performed a shutdown safety review of the Second Refueling Outage prior to its
start.
This review was performed following the NUMARC guidelines.
The goal was to
maintain, throughout the outage, at least three sources of power available to the station. On
March 23, 1992 these three sources were the two offsite 115 KV lines, designated
line No.
~
~
Jg
1
Page 6
Mr. Marvin W. Hodges
May 13, 1992
oivision
II Emergency
D'esel Generator.
Th'dequate
defense-in-depth
for the event th t o
d.
After the March 23,
1992
event,
the
Independent
Safety
Engineering
Group's, Safety
Assessment
Report concluded that at no time during the March 23, 1992 loss of offsite power
event was there any danger to the fuel, the plant, or to the health and safety of the public
because
of decay heat loads.
In conclusion, Niagara Mohawk has assessed
the safety aspects associated with the March 23,
1992 ALERTevent, and has taken or willtake the necessary corrective actions to minimize the
potential for loss of all Control Room annunciators and to address other identified deficiencies.
Very truly yours,
.~a~
Exec. Vice President - Nuclear
BRS/JTP/Imc
(A:84888.0oc)
xc:
CSfr~>T:"..T.;Martin",Regional "Administrator"Region~le~
Mr. J, E. Beall, Team Leader, Division of Reactor Safety
Mr. W. L. Schmidt, Senior Resident Inspector
Mr. R. A. Capra, Director, NRR
Mr. J. E. Menning, Project Manager, NRR
IV!r. L. E. Nicholson, Section Chief, Reactor Projects, Branch No. 1B
Records Management
~: