ML17174A894
| ML17174A894 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 09/20/1991 |
| From: | Boger B Office of Nuclear Reactor Regulation |
| To: | Reed C COMMONWEALTH EDISON CO. |
| Shared Package | |
| ML17174A895 | List: |
| References | |
| NUDOCS 9110020298 | |
| Download: ML17174A894 (6) | |
See also: IR 05000237/1991201
Text
.....
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D. C. 20555
Docket Nos. 50-237
and 50-249
Mr. Cordell Reed
Senior Vice President
Commonwealth Edison Company
Licensing Department - Suite 300
Opus West III
1400 Opus Place
Downers Grove, IL
60515
Dear Mr. Reed:
September 20, 1991
SUBJECT:
ELECTRICAL DISTRIBUTION SYSTEM FUNCTIONAL INSPECTION AT DRESDEN
(50-237/91-201; 50-249/91-201)
We are forwarding the report of an electrical distribution system functional
inspection (EDSFI) performed July 8 through August 9, 1991, involving activi-
ties authorized by Operating License Nos. DPR-19 and DPR-25 for the Dresden
Nuclear Power Station, Units 2 and 3. This inspection was conducted by the
Special Inspection Branch of the Office of Nuclear Reactor Regulation with the
support of Region III.
An exit meeting was held on August 9, 1991, during
which we discussed the team's findings with Messrs. L. DelGeorge and D. Galle
and members of their staff.
The inspection team focused on the operational readiness and functionality of
the electrical distribution system by reviewing 1) design documentation to
confirm proper implementation of design requirements, 2) installed equipment
for consistency with design documents and 3) adequacy of testing, maintenance
and surveillance procedures and their implementation.
These reviews provided
insights to the team as to the effectiveness of engineering and technical
support.
The team concluded that some equipment in the electrical distribution system,
in its existing configuration, had riot been shown capable of performing its
required safety function during certain degraded grid voltage conditions.
Specifically, the team determined that a voltage just above the existing
degraded voltage relay setpoint of 3708 volts on the 4-kV safety bus would not
be sufficient to start and operate safety-related equipment required to function
during accident conditions.
Your prompt compensatory measures, Operating Order
- 20-91, Revision 0, which prbvided sufficient administrative controls to allow
continued operation of both units, has replaced one feature of the automatically
initiated protection with manual actuation. Subsequent to the exit meeting,
following a Unit 3 reactor trip, the plant experienced voltage fluctuations
and an apparent voltage drop on the 4-kV bus that remained below the normal
voltage levels for several hours, but the operators failed to implement the -
9110020298 910920
I
~DR ADOCK 05000237
September 20, 1991
Mr. Cordell Reed
- 2 -
operating order.
As a r~suli of this event, Op~rating Order #20-91 was revised
to require mandatory operator actions associated with these degraded grid
voltage conditions.
However, the indication of voltage fluctuations following
unit trips needs to be furthe~ evaluat.ed. Addi.tion.ally, this event emphasized
the importance of restoring the automatic: actuation mode of the undervoltage
protection.
-*
"*
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The team que~tioned.*"th~. operability of ce.rtain motor:ci*perated valves and
associated 120-volt control circuits during the. degraded voltage condition,
even with the 4-kV. bus voltage: administratively contro.lled at 3850 volts.
In
response to these *conc~rn,s, the "lic~nsee completed preliminary calculations
..
which indicated that the .temporar:-y compensato,ry m~asures ~o control the voltage
on the 4-kV bus above 3850 volts.~ould bound the ~pecific equipment.
The team
requested that you evaluate additional MOVs an~;control circuits within one week
of the exit meeting. This was ~ccomplished, a~ d6cumerited in our letter dated
August 16, 1991.
Inadequate calculations and failure to act on the results of calculations
contributed t~ *the erroneous SE{tpoint-.on the 4-kV bus *. It did not appear that
your staff had adequately assessea the safety significance of de.sign deficiencies
and results of calculations, determined the need for safety evaluations, or
i.nitiated prompt correctiv~ actions. These concerns are summarized in the
Executive Summ_ary of the enclosed inspection report.
The deficiencies described in the enclosed inspection report will be reviewed by
the Region III office for enforcement action.
In accordance with 10 CFR 2.790 of the Commission's regulations, a copy of this
letter and 'its enclosures will be placed in the NRC Public Document Room.*
No response is required to this letter. Should you have any questions concern-
ing this inspection~ we will be pleased to discus~ them with you *.
Enclosure:
- NRC Inspection Report 50-237
and 50-249
cc: See next page
- See previous
RSIB:DRIS*
PS Ko 1 tay:
09/17/91
concurrence
SC: RSIB: ORIS*
DPNorkin
09/17/91
Sincere Jy,
Bruce A. Boger, *Di rector
Divisiori of Reactor Projects III/IV/V
Office of ~utl~ar Reactor Regulation
C: RSIB: ORIS*
EVImbro
09/19/91
D:DRIS*
BKGrimes.
09/19/91
DRPW:NR~
BABoger
09flo/91
. :
Mr. Cordeli Reed
- 2 -
.
I
,.
indication of voltage fluctuations following unit trips needs to be further
evaluated. Additionally, this event emphasized the importance of.restoring the
automatic ~ttuation mode of the undervoltage protection.
The team questioned the operability of certain motor-operated valves and
associated 120-volt control circuits.during the degraded voltage condition,
even with the 4-kV bus voltage administratively controlled at 3850 vqlts.
In
response to these concerns, the licensee compl_eted preliminary calculations
which indicated that the temporary compensatory measures to control the voltage
on the 4-kV bus above 3850 volts would bound the specific equipment.
The team
requested that y9u evaluate additional MOVs and control circuits within one week
of the exit meeting. This was accomplished, as documented in our letter dated
August 16, 1991.
Inadequate calculations and failure to att on the results of calculations
contributed to th~* erroneous setp6int on the 4-kV bus. It did not ~ppe~r that
. your staff had adequately assessed the safety significance of design deficiencies
and results of calculations_, determi.ned the need for safety evaluations, or
initiated prompt corrective actions. These concerns are surrunarized in the
~xecutive Suirnnary of. the *enclosed inspection report.*
The deficiencies described in the enclosed inspection report will be reviewed by
the Region III office for enforcement action~
, rn* accordance with 10 .CFR 2.790 of the Corruniss:ion's regulations, a copy of this.
- letter and its enclosures will be placed in the.NR~ Public Document Room.
No response is required to this letter. Should you have any questions concern-:-
ing this inspection, we will be pleased to*discuss them with you.
Sincerely,
Bruce A. aoger, Director
Division*of Reactor Projects III/IV/V
Office of Nuclear Reactor Regulation
Enclosure:
NRC Inspection Report 50-237
and 50-249
cc:
See next page .
- See previous-concurr~-n~e---*-*:_,~-~ _j?-i?-.. .. c---
.* -
__ ffJ?_ -
RSIB:DRIS*
SC:RSIB:'DRIS* .. C:RSIB::DRIS'/n D:DRIS
PSKoltay:
DPNor~in *
- EVImbro. :_:
BKGrimes
09/p /91
09/17 /91
.
"' 09//~/91 : . '
09//j /,,91
DRPW:NRR
BABoger
09/ /91
Mr. Cordell Reed
'_. 2 ..:.
apparent susceptibility to voltage fluctuations following unit trips needs to
be further evaluated. Additionally, this event emphasized the .importance of
returning the second level undervoltage protection to its automatic actuation
mode.
The team questioned the operability of certain motor-operated valves and
associated 120-volt control circuits during the degraded voltage condition,
even with the 4-kV bus voltage administratively controlled at 3850 volts.
In
response to these concerns, the. licensee completed preliminary calculations
_
which indicated that. the temporary compensatory measures to control the voltage
on the 4-kV bus to 3850 would appear to bound the specific equipment.
The team
requested that the licensee evaluate additional MOVs_ and control circuits
within one week of the exit m~eting. *
1nadequate cal~ulaiions contrib~ted to the ~~roneous setpoint on the 4-kV b~s.
Overa 11, it did not appear that your staff had adequately asse~sed the safety
significance of design deficiencies and ~~sults of c~lculations, det~rmined th~
need for safety evaluations, and initiated prompt corrective acti_ons.
These
concerns are summarized in the Executive Summary of the enclosed inspection
report.
The inspection* findings indicated that certain activities were apparently not
conducted in full compliance with NRC requirements.
The deficiencies des.cribed
in the enclosed inspection report will be reviewed by the Region III office for
any enforcement action.
In accordance with 10 CFR 2.790 of the Commission's regulations; a copy of this
let~er and its enclosures will be placed in the NRC Public Document Room.
No_ response _is required to this letter. Should you have any questions c.oncern-
ing this inspection, w.e will be pleased to discuss them. with you.
Enclosure:
Sincerely,
Bruce A. Boger, Director
Division of Reactor Projects III/IV/V
Office of Nuclear Reactor Regulation *
NRC Inspection ReRort 50-237
and 50-249
cc:
See next page .
~SIB:DRIS
Q1 PS Ko 1 tay:
09/ll/91
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iD':DRIS
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EVImbro .
~K~rim~s
09\\119.1: ... '*09/ ' /91
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DRPW:NRR
BA Boger
09/ /91
Mr. Cordell Reed
Conunonwealth Edison Company
cc:
Michael I. Miller, Esq.
Sidley and Austin
One First National Plaza
Chica90, Illinois 60690
Mr. J. £enigenburg
Plant Superintendent
Dresden Nuclear Power Station
Rural Route #1
Morris, Illinois 60450
U.S. Nuclear Regulatory Commission
Resident Inspectors Office
Dresden Station
Rural Route #1
Morris, Illinois 60450
Chairman
Board of Supervisors of
Grundy County
Grundy County Courthouse
Morris, Illinois 60450
Regional Ad111inistrator
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Nuclear Regulatory Conunission, Region III
799 Roosevelt Road, Bldg. #4
Glen Ellyn, Illinois 60137
I 11 i noi s Department of Nuclear Safety
Office of Nuclear Facility Safety
1035 Outer Park Drive
Springfield, Illinois 62704
Robert Neumann
Office of Public Counsel
State of Illinois Center
100 W. Randolph
Suite 11-300
Chicago, Illinois 60601
Dresden Nuclear Power Station
Unit Nos. 2 and 3
Distribution:
Docket Files 50-237 and 50-249
RSIB R/F
ORIS R/F
TEMurley, NRR
FJMiraglia, NRR
WTRusse 11, NRR
JGPartlow, NRR
BKGrimes, NRR
EVImbro, NRR
PS Ko 1 tay, NRR
DPNorkin, NRR
RLSpessard, AEOD
BABoger, NRR
RJBarrett, NRR
BLSiegel, NRR
ACMoore, NRR
DHills, RIII
Regional Administrators
Regional Division Dirtctors
Inspection Team
LPDR
ACRS (3)
OGC (3)
lS Distribution
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