ML17174A896
| ML17174A896 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 09/19/1991 |
| From: | Imbro E, Koltay P, Norkin D Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17174A895 | List: |
| References | |
| 50-237-91-201, 50-249-91-201, NUDOCS 9110020315 | |
| Download: ML17174A896 (37) | |
See also: IR 05000237/1991201
Text
U.S. NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
Division of Reactor Inspection and Safeguards
NRC Inspection Report:
50-237/91-201
50-249/91-201
License No.:
DRP-19
DRP-25
Docket Nos.:
50-237 and 50-249
Licensee:
Commonwealth Edison Company
Facility Name:
Dresden Nuclear Power Station Units 2 and 3
Inspection Conducted:
July 8 through Aug~st-9, 1991
Inspection Team:
P. Koltay, Team Leader, NRR
M. Miller, Operations Engineer, NRR
B. Thomas, Engineer, NRR
L. Tran, Electrical Engineer, NRR
D. Butler, Reactor Inspector, Region III
W. Scott, Reactor Inspector, Region III
NRC Consultants:
S. Leelananda, (Atomic Energy Canada Ltd.)
N. Padhi, AECL
Prepared by:
Reviewed by:
Approved by:
G.
Skinner~ AECL
p;~~;~,;~:~
Special Inspection Development Section A
Special Inspection Branch
Division of Reactor Inspection and Safeguards
ffice of Nuclear Reacto Regulation
~*~
- or in, ect1on
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Inspection Development Section A
Special Inspection Branch
Division of Reactor Inspection and Safeguards
Office of Nuclear Reactor Regulation
c-r~k-
Eugene V. Imbro, Chief
Special Inspection Branch
Division of R~actor Inspection and Safeguards
Office of Nuclear Reactor Regulation
. 9110020315 910920
. PDR
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EXECUTIVE SUMMARY
A Nuclear Regulatory Conm1ission inspection team conducted an electrical distri-
bution system functional inspection from July 8 through August 9, 1991 at
Dresden Units 2 & 3.
The objectives of the inspection were to determine if the
electrical distribution system (EDS) was capable of performing its intended
safety functions as required by its design basis and to assess the utility's
capability to provide engineering and technical support to the Dresden Nuclear
Power Station as well as assess utility management's effectiveness in imple-
menting EDS configuration controls and root-tause analysis programs.
The team reviewed a sample of design calculations, studies, and drawings, and
concluded that the EDS may not have performed its intended safety functions under
certain degraded grid voltage conditions. Specifically, during a degraded grid
voltage condition just above the degraded grid trip set point of 3708 volts on
the 4-kV bus, adequate voltage may not have been available to start and operate
safet,y-related equipment required to mitigate accidents.
On the basis of the team's concern, the licensee identified the apparent worst
case safety-related load as the Unit 2, Division 2 emergency diesel generator
(EOG) cooling water pump.
The licensee performed preliminary calcu.lations that
determined that the minimum starting current for the cooling water pump was
3960 volts and the minimum running current was 3850 volts. Accordingly, the
licensee implemented compensatory measures to administratively start the EOG
cooling water pump at 4000 volts and manually transfer the power for the 4 kV
safety-related buses from the offsite supply to the EDGs at 3850 volts. These
measures also assured th~ functioning of similar pumps on Unit 2 Division 1 and
on Unit 3.
The team questioned the operability of certain motor-operated valves (MOVs) 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 v.olt would appear to bound the voltage required by
specific equipment.
The team requested that the licensee evaluate additional
MOVs and control circuits within one week of the exit meeting. This was
accomplished, as documented in the licensee's letter dated August 16, 1991.
The preliminary results of the licensee's electrical load monitoring system,
"ELMS Running Voltage Summary,
11 dated November 1990, indicated a potential
- deficiency in the second- level undervoltage protection relay set points. The
calculations showed voltages at certain safety-related motor control centers to
be ltss than the voltage required to ensure the operability of motors. The.
licensee had failed to identify and evaluate this significant condition adverse
to quality and therefore did not take prompt corrective action to correct the
condition before the inspection.
Weaknesses were identified in the area of design calculations.
In at least one
instance, inadequate calculations contributed to erroneous setting of the
degraded grid voltage relay set points.
In other instances, such as EOG
- loading, short cirtuft; and breaker coordi"nation calculations, the identified
weaknesses in calculation methodology and assumptions did not result in
operability concerns.* However, the fact that a system or component was found to
bt operable, not withstanding errors in the calculations, does not indicate
that such errors are i~consequential.
The team found weaknesses in root-cause analysis, post-modification testing,
and fuse controls, even though the licensee had developed and/or implemented
new compreh~nsive programs in some of these areas.
ii
TABLE OF CONTENTS
EXECUTIVE SUMMARY ........................................................
i
1.0
INTRODUCTION ........................................................
1
2.0
ELECTRICAL SYSTEMS ************..*********.*******************.******
"
£.
2.1 Offsite Power System ......................................**.*.
2
2 .1.1
2 .1.2
2 .1.3
2.2 Class
2.2.1
2.2.2
2.2.3
2.2.4
2.2.5
2.3 Class
2.3.1
2.3.2
2.4 Class
2.4.1
2.4.2
2.4.3
2.4.4
Surge Protection and Protective Relaying **************.*
3
Automatic Transfer......................................
3
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
lE 4160-Vac Systeni . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . *
3
Switchg~ar Short Circuit Ratings ************************
4
Protective Relaying .........**.....***.*..*..*..*..*....
4
Degraded Grid Undervoltage Protection *******************
5
Emergency Diesel Generators *****************************
7
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7
IE 480-Vac System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . * . . .
7
480 Volt SystE:m Voltage Regulation **********************
8
Conclusions ........... -...................................
8
lE 250-Vdc and 125~Vdc Systems...........................
8
Voltag~ Drop Studies ..........*..*..*****...*..***.**...
8
250-Vdc and 125-Vdc System Battery Sizing ***************
9
Fuse and Breaker Coordination ***************************
9
Conclusions ...... ~ ..*.......*.***....*******......*.*..* 10
2.5 Protective Device Coordination ********************************* 10
2.5.1 480-Vac
2.6 Cable Ampacity
Coordination ************************************
.................................................
10
11
2.7 Electrical Design Calculat1uns **.*******.*********.************ 11
3.0 MECHANICAL DESIGN REVIEW *.*.*********.**********.*******************
11
3.1
HVAC Systems Supporting the Emergency
Dies~l Generator *Rooms ......**.....**.*.......**.***..****... 12
3.2 Mechanical/Electrical Power Conversion for Major Loads
12
3.3 Emergency Diesel Generators ******************************.***** 12
3.3.1
3.3.2
3.3.3
3.3.4
3.3.5
3.3.6
Fuel Storage Capacity ..**....*****.......**.*..*.***....
Fuel Oil Qua 1 ity * ....................................... .
Emergency Diesel Generator Day Tank ***.*****************
Classification of Diesel Fuel System ********************
Emergency Diesel Generator Air Start System *************
Conclusions .......................................*.....
12
13
13
13
14
14
4.0
EQUIPMENT TESTING AND SURVEILLANCE ***************.****************** 14
4.1
4.2
4.3
4.4
Emergency Diesel Generator Testing **************************.**
Relay and Instrument Calibration Program ********.**************
Fuse Contra 1 ******..********..*********.********.*********..***
Conclusions
14
14
15
15
5.0
SYSTEMS WALKDOWN INSPECTION **.**.**.******************************** 15
6.0
ENGINEERING AND TECHNICAL SUPPORT REVIEW **************************** 16
6.1
6.2
6.3
6.4
6.5
Technical Staff ********.***********.***************************
Self Assessments .............................................. .
Root Cause Analysis and Corrective Action Program **************
Design Changes and Modifications ************.******************
Conclusions ..............................
~ ................... .
16
16
17
17
18
7.0
EXIT MEETING ***********************************~******************** 18
- APPENDIX A - Summary of Inspection Findings ****************************** A-1
APPENDIX B - Summary of Observations ****************************** ****.***
B-1
APPENDIX C - Exit Meeting Attendees ************************************** C-1
1.0
INTRODUCTION
The Nuclear Regulatory Conunission (NRC) staff of the Special Inspection Branch,
Office of Nuclear Reactor Regulation, initiated inspections of the electrical
distribution system (EDS) at nuclear power plants because previous inspections,
e.g., Safety System Functional Insptctions, had identified deficiencies in the
EDS which could affect power to safety-related equipment and thereby compromise
plant design safety margins.
For example, deficiencies were identified in the
areas of control of load growth on safety buses, design calculations, engineer-
ing modifications, undervoltage protection, and testing/qualification of EDS
equipment.
The deficiencies identified during these inspections were attributed,
in part, to inadequate engineering and technical support.
The objectives of this inspection were to assess the adequacy of the Dresden
Nucledr Power Station EDS and the capability and performance of the licensee's
engineering and technical support in this area.
For the purpose of this
inspection, the EDS included all emergency sources of power and associated
equipment providing power to systems relied on to remain functional during and
following design-basis events. The EDS components included the offsite cir-
cuits from the 345-kV and 138-kV offsite power grid switchyard, three emergency
diesel generators, 250 Vdc and 125 Vdc Class lE batteries, distribution trans-
formers, 4160-Volt switchgear, 480 Vac load centers and motor control centers,
and 120 Vac control circuits *
. The inspection team reviewed the ad~quacy of emergency onsite and off site power
sources for EDS equipment, protection for undervoltage conditions, the electri-
cal load study and regulation of voltage to essential loads, protection of EDS
eq~ipment and loads from postulated fault currents, and coordination of the
interruptfng capability of protective devices.
The team also reviewed mechani-
cal systems supporting the EDS, including air start, lube oil and cooling
systems for the emergency diesel gerierator as well as cooling and heating
systems for EDS equipment.
The team verified nameplate data and locations of
installed EDS equipment for conformance to design documents and reviewed
equipment qualification testing and calibration records. It assessed the
capability and performance of the licensee's engineering an.d technical support
functions with regard to ~he EDS, including organization and key staff, root
cause analyses for failurts and recurring problems, and engineering involvement
in design modifications and operations.
The NRC team reviewed EDS design conformance with General Design Criteria (GDC) 17 and 18 and appropriate criteria of Appendix B to 10 CFR Part 50.
The team
reviewed plant technical specifications, the Updated Final Safety Analysis
Report and the Safety Evaluation Report to determine whether technical require-
ments and licensee conunitments were being met.
The areas reviewed and the safety significance of identified deficiencies are
described in this report. Conclusions are provided in each section. The team
has characterized its findings within this report as deficiencies, unresolved
items, or observations. Deficiencies are either a) the apparent failure of
the licensee to comply with a requirement or b) the apparent failure of the
licensee to satisfy a written conmitment or to conform to the provision of
applicable codes, standards, guides or accepted industry practices when the
1
convnitment has not been made a legally binding requirement.
Unresolved items
invo1vt a concern about which more information is required to ascertain
whether it is acceptable or deficient. Observations are items considered
appropriate to call to licensee management attention but which have no
apparent direct regulatory basis. Any enforcement action from these findings
will be determined by the NRC Regional Office. A sunvnary of the findings is
provided in Appendix A with a corresponding number and a reference to the
section of this report in which it is discussed. Appendix B is an index of
team observations. A list of persons who attended the exit meeting is provided
in Appendix C.
2.0
ELECTRICAL SYSTEMS
The scope of the inspectior1 included the design of both the AC and DC electri-
ca 1 power distribution systems of Units 2 and 3. The team paid particular
attention to a sample load path, or "vertical slice," through the Class lE
electrical power distribution system from the power source to load device
terminals.
The "vertical slice" selected by the team was a path through the
Division 2 electrical distribution system of Unit 2.
Thus the review of the electrical distribution system extended from the sta-
tion's 345 kV/138 kV switchyard, through the 4160 volt power system, the 480
volt power system, the 120 volt AC system and 250/125 volt DC system.
The AC
equipment reviewed included the reserve auxiliary (start-up), unit auxiliary
and load center transformers; medium and low voltage switchgear; motor control
centers; emergency diesel generators; protective relaying and surge protection.
The DC equipment reviewed included the station batteries, battery chargers, DC
power panels and related distribution devices.
The design documents or calculations were not always adequate, or even avail-
able, to demonstrate the acceptability of the design features.
The team noted
weaknesses in some calculations regarding the lack of independent reviews,
unverified assumptions, and oversimplified methodologies.
In such cases, the
licensee verified assumptions and performed preliminary bounding calculations
during* the inspection as required to demonstrate the adequacy of the design to
perform its intended safety function for the inspection sample selected *.
2.1 Offsite Power System
The team reviewed the capability of the licensee's offsite grid system to
provide acceptable electrical power to the station's safety-related onsite EDS.
The switchyard serving the station included a 345-kV section and a 138-kV
section. The 345-kV section consisted of two ring buses connected by a tie
circuit breaker. Six transmission lines served the 345-kV switchyard section
with three lines connected to each ring bus.
The 138-kV section of the switch-
yard tonsisted Lf a four-section bus which was served by six 138 kV transmis-
sion lines.
The 345-kV section and the 138 kV section were intertied by two
300-MVA autotransformers which were located at the Dresden switchyard.
Autotransformers were installed at various locations in the licensee's trans-
mission system grid to tie together the 345-kV and 138-kV systems.
Jh_e _preferr~d Qffsite power supply for each ~nit_ was through its respective_ .
reserve auxiliary transformer with an alternate supply from the other unit via
a 4.16-kV bus crosstie. Unit 2's reserve auxiliary transformer was connected
to the 138-kV switchyard section; Unit 3' s reserve auxi 1 iary transformer was
connected to. the 345kV section.
2
.,
The licensee's "System Planning Department Opf:rating Guide No. 2-1," Revised
Ma.>' 1, 1991, showed the expected maximum and minimum 345-kV and 138-kV trans-
mission system voltage levels at the Dresden switchyard for the surmier of 1991
through the spring of 1992 were 345-kV to 364-kV and 145-kV to 131-kV,
respectively.
2.1.1 Surge Protection and Protective Relaying
Protection of the reserve auxiliary transformers, including their secondary
circuit and devices, from lightning and switching surges was provided by surge
arrestors applied on the primary side of the transformers. The licensee was
initially unable to demonstrate acceptable surge protection based on the
installed arrestors. However, as a result of the team's concern the licensee
performed calculation 8900-71-EAD-1, Revision 0, dated July 24, 1991, "Analysis
of Transferred Surges from the 138-kV System." This calculation demonstrated
_acceptable surge protection for Unit 2's reserve auxiliary transformer and
secondary circuits, which were included in the load path selected by the team.
2.1.2 Automatic Transfer
During the startup and normal shutdown of a unit, the 4.16-kV buses for the
engineered safeguards Division 1 devices for that unit were manually trans-
ferred by a "live bus" scheme.
This meant that both the UAT and RAT were
temporarily paralleled to Division 1, thus precluding any significant tran-
- sients on rotating equipment.
The buses for Division 2 devices normally
remained connected to the reserve auxiliary transformer and were not trans-
ferred.
In an emerg~ncy, following unit trip, the buses fed by the unit
auxiliary transformer were to be automatically fast bus transferred to the
respective unit's reserve auxiliary transformer.
However, the fast bus trans-
fer scheme di_d not include synchronization-checking logic. The team questioned
the licensee regarding the potential for high transient torques that could have
been developed in rotating ~quipment resulting from an out-of-phase transfer
between the 345-kV and 138-kV power sources for the Unit 2 auxiliaries.
On the
basis of system operating requirements that existed with multiple automatic
transformer ties between the 345-kV and 138-kV systems, out-of-phase transfers
would have been precluded~ Further, the licensee's anillysis performed during
the inspection demonstrated that motors at Dresden, upon transfer, would be
subjected to a volts per hertz difference of less than 1.33 per unit as recom-
mended by American National Standards Institute (ANSI) Standard C50.41-1982,
"Polyphase Induction Motors for Power Gen~rating Stations."
2.1.3 Conclusions
The team did not identify any operability concerns directly relating to the
switchyard design.
The reserve auxiliary transformer sizing, surge protection
and protective relaying appeared acceptable.
The automatic fast bus transfer
schemes did not appear to subject safety-related motors to excessive torques
and stresses.
2.2 Class lE 4160 Vac System
The 4-kV distribution system consisted of six buses that supply power to plant
--auxiliary equipment*
Non-safety buses 21 and 22 supp-ly power to--the -feedwater
3
pumps and the reactor water recirculation pumps through 350 MVA metal-enclosed
switchgear. Safety-related buses 23, 24, 23-1, and 24-1 supply power to safety
and non-safety loads through 250 MVA metal-enclosed switchgear.
Normal power
was supplied to the 4-kV system of each plant through two auxiliary transform-
ers. The unit auxiliary transformer was connected to the main turbine genera-
tor leads for both units, and the reserve auxiliary transformer was connected
to the 138-kV switchyard for Unit 2 and the 345-kV switchyard for Unit 3.
Emergency AC power was supplied by two diesel generators, each of which is
rated at 2600-kw at 0.8 power factor with a 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> overload rating of 2860 kw.
Diesel generator 2 supplied bus 24-1, while the shared unit, diesel generator 2/3,
supplies ESS bus 23-1.
Buses 23 and 24 may be supplied by the diesel generators
through buses 23-1 or 24-1, respectively.
2.2.1 Switchgear Short-Circuit Ratings
The team determilled by reviewing calculations that several 350-MVA and 250-MVA
circuit breakers in the 4kv system (including safety-related breakers on buses
23 and 24) could receive fault currents in excess of their maximum interrupting
ratings.
In addition, some safety-related 250-MVA and non-safety related 350-
MVA breakers could receive fault currents in excess of their momentary ratings.
Safety-related 250-MVA breakers could experience fault currents as high as 114
percent of their interrupting ratings and 118.4 percent of their momentary
ratings. Although a safety evaluation provided b~ the licensee concluded that
the operability of engineered safety* feature (ESF) loads would be maintained
because of redundancy and availability of emergency power sources, the inade-
quate short circuit rating of breakers was considered by the team to be a
design deficiency.
The licensee identified conditions that exceeded the ratings of the circuit
breakers described above, on several occasions as early as 1982.
However,
although the licensee has developed a prelimiriary study of proposed recommended
actions that would resolve the problems by 1996 corrective actions had not been
initiated (see Appendix A, Deficiency 91-201-01).
2.2.2 Protective Relaying
-~
The unit substation feed overcurrent relays do not fully protect the
4160volt/480volt unit substation transformers for faults on the secondary
windings below approximately 14,400 amperes. This could result in destructive
failure of a PCB-filled unit substation transformer. Since this condition would
generally only affect one safety division, it does not present an operability
concern.
However, this is an electrical design weakness with personnel safety
implications (see Appendix B, Observation 91-201-01).
The licensee could not provide documentation to establish that cables supplying
4-kv loads were adequately protected against available short circuit currents.
A calculation performed by the team indicated that the #2 AWG cable feeding the
reactor building cooling water pump 2A was not adequately protected. Available
short circuit current was calculated to be approximately 27,360 amperes.
The
cable was protected to approximately 13,000 amperes, during the approximately 5
cycle period it takes the breaker to actuate.
However, the team determined
that adjacent cabling would not be affected.
4
2.2.3 Degraded Grid Undervoltage Protection
Branch Technical Position PSB-1 dated July 1981 required two levels of
undervoltage protection, loss of voltage and degraded grid voltage, to ensure
that accident mitigating loads (such as pump motors, motor operated valves and
control circuits) would perform their safety functions.
At the time PSB-1 was
prepared, loss of voltage protection already existed at operating plants.
However, degraded grid voltage protection, referred to as second level
undervoltage protection, typically did not exist.
In accordance with PSB-1,
the selection of undervoltage and time delay setpoints was to be determined
from an analysis of the voltage requirements of the Class lE loads at all
onsite system distribution levels.
The team reviewed documentation intended to support the established second
level undervoltage protection relay setpoint for Dresden Units 2 and 3.
The
licensee had established a setpoint of approximately 90% (3708 volts to 3784
volts) on the 4160 volt safety-related buses. It appeared to the team that the
licensee had not considered the starting and/or running voltage requirements of
the various safety-related devices.
The basis of the degraded voltage relay
setpoint was an oversimplified calculation (dated February 21, 1984) which was
not in accordance with the quality assurance requiren1ents of Appendix B of
Additionally, the most critical, or bounding, voltage requirements
under the
11 distribution system loading were not considered.
In response to the team's concern, the licensee performed a preliminary (unver-
ified) calculation, NED-E-EIC-0050, Revision 0, dated July 24, 1991 "Adequacy
of DG Cooling Water Pump 2 Und~r Degraded Voltage Conditions," to determine the.
required voltage levels on 4160 volt bus 29-1 to support starting and running
of the assumed
11 motor load.
The load analyzed was the 460 volt,
87-KW (129A full load) canned rotor motor associated with the Division 2 di~sel
generator cooling water pump.
Based on assumed motor characteristics, circuit
data and 480 volt system
11 loading, the licensee determined that
motor starting and running voltage requirements at the 4160 volt bus were 3960
volts (95.2% of 4160 volts) and 3850 volts (92.5% of 4160 volts), respectively.
Thus, the licensee determined that the second level undervoltage relay trip
setpoint of 90 percent wa~ too low to assure the starting of the DG cooling
water pump.
Therefore, the licensee issued Operating Order 20-91, dated August
1, 1991, which directed the plant operators to start the diesel generator
cooling water pump when the associated 4160 volt bus degraded to 4000 volts, as
indicated by a computer alarm annunciator, to preclude motor starting problems
if bus voltage continued to degrade.
The operating order also instructed that,
if 4160 volt bus voltage degraded to 3850 volts and the condition existed for
more than one minute, the affected 4160 volt bus would be separated from the
offsite source by opening the associated tie breaker. This action would result
in the automatic starting and loading of the associated diesel generator on the
affected 4160 volt bus, thus restoring normal grid voltage.
The new administratively controlled degraded grid undervoltage setpoints which
formed the basis for the operating order were based on pre 1 iminary ca lcu la-
t ions.
The licensee stated that their target date for formalizing calculation
NED-E-IC-0050 was September 30, 1991. These calculations will include the
required analysis to bound the 480-Vac motor operated valves and motor control
center 120 VAG control-circuits.- Similar calculaticm$ to ana1yze 4160 volt
5
Unit 2 bus 28-1 and Unit 3 buses 38-1 and 39-1 were targeted for formal issue
by November 18, 1991 (see Appendix A, Deficiency Item 91-201-02).
Based on the 3850 volt setpoint, the team raised several potential operability
concerns about the adequacy of voltage for motor operated valves and motor
control center 120 VAC control circuits. For motor operated valves 2301-4 and
2301-48, the licensee's calculations indicated that 61.7i and 51.6% of the
rated motor voltage would be available at the terminals, whereas the manufac-
turer had recommended a minimum of 70 percent.
For 120 VAC control circuits
for the Unit 2 Division 1 DG cooling water pump and the LPCI loop select valve,
the calculations indicated that terminal voltages at the motor contactor would
be less than the manufacturer's reconvnendations for 85 percent of the rated
voltage.
In order to resolve these operability concerns, the licensee performed prelimi-
nary calculations which revised several conservative assumptions of the previ-
ous calculations (e.g., ambient temperatures, circuit length) and which
demonstrated that voltages available at the terminals would marginally satisfy
equipment requirements.
In order to assure that the administratively controlled degraded grid voltage
setpoint of 3850 volts bounded all safety-related equipment for operability,
the licensee stated that the following additional evaluation would be accom-
plished within one week of the exit meeting:
0
0
0
Finalize preliminary design calculations to verify that terminal voltage
.values for all safety-related motor operated valves were at least 70
percent of the rated motor voltage.
Verify that motor operated valves developed the required starting torques
and stroke times at a voltage equal to the minimum calculated motor
voltage.
Identify a representative sample of additional 120 volt AC control cir-
cuits and demonstrate that the minimum voltage requirement of 102 volts
(85 percent) was met at the motor starter contactors or that the contactor
wi11 pick up at the minimum calculated voltage.
By a letter dated August 16, 1991 and a subsequent telephone conference, the
licensee stated that at least 70 percent of the rated voltage would be avail-
able at the motor terminals of all motor-operated valves (MOVs).
However, for
safety-related MOV motor starter contactors (reactor recirculation discharge
valve 202-58 and low pressure coolant injection (LPCI) injection valve
1501-22E), the vendor-recommended contactor voltage of 102 volts (85 percent of
the nominal voltage) could riot be met.
Voltage drop calculations showed approxi-
mately 89 volts (74 percent) at the CR109 (NEMA Type 2) style contactors for
each circuit. Initially, the licensee conducted a field test on a similar
style, but nut identical, contactor (CR106), and determined that consistent
contact closure could be established at 90 volts. Recalculated voltage drops
on the subject circuits showed that 92.5 volts may be available to the contactors,
giving a margin of 2.5 volts for operability. Subsequently, the licensee
- tested al 1- safety-related_ CRlO~ (NEMA Type 2) MOV contactors on both units
(12 valves, 24 contactors) and determined ill but three contactors were operable.
6
'-
The motor starter on one of the valves containing two of the failed contactors
was replaced and on retest passed.** The third contactor was determined not to
be required.
2.2.4 Emergency Diesel Generators
Transient and static loading capabilities were demonstrated in Calculation
7317-33-19-2, dated April 12, 1991, "Diesel Generator Loading Under Design
Basis Accident Condition." Transient loading capability was demonstrated using
a dead load pickup curve that showed the capability of the diesel generator to
start and accelerate all sequenced loads, including transient loading imposed
by pre-existing loads. The calculation demonstrated a maximum sequenced
running load of 2325 kw, a continuous rating of 2600 kw and a 2000-hour over-
load rating of 2860 kw.
However, the calculation did not clearly describe
objectives or acceptance criteria relative to transient and static loading
capabilities.
In addition, the calculation did not compare the static load
profile to the OG's output capacity.
OG static loading capability was not
stated in the body of the calculation and could not be found in the references
stated in the calculation. The licensee demonstrated, based on successful
periodic tests, margins, and conservatisms in the calculation, that the OG
would perform its safety function.
The 1990 surveillance tests showed that the actual DG fast starting times and
ECCS loading sequence times, were different than the times stated in several
UFSAR sections.
The team reviewed the safety evaluation for the current fuel
load performed by Advanced Nuclear Fuels Corporation (ANF), titled "Dresden
Units 2 and 3 LOCA-ECCS Analysis MAPLHGR Results for ANF 9x9 Fuel," and con-
cluded that the reload analysis safety evaluation bounded the measured DG and
ECCS operating times.
The licensee had embarked on an UFSAR rebaseline program for Dresden to address
the type of discrepancies identified above.
The UFSAR section writers have
been instructed to identify and reconcile conflicting information.
In response
to the team's concern, the licensee stated that the Nuclear Fuel Services
Department current fuel load analysis would be an input document for the
Dresden rebaseline program which was scheduled for completion by October 1993.
2.2.5 Conclusions
The team concluded that the degraded grid second level undervoltage protection
trip setpoint was not adequate.
In the event of a degraded grid voltage at a
level slightly above the second level trip setpoint, it appeared that accept-
able operation of all safety-related electrical devices could not be assured.
To resolvt the team's concern regarding operability of equipment at degraded
grid voltages, the licensee implemented interim compensatory measures (Operat-
ing Order 20-91). However, additional licensee actions are required as described
in Section 2.2.3.
2.3
Clas~ lE 480-Vac System
The 480-V system was supplied from 4-kV buses 23, 24, 23-1, and 24-1 through
six 4160":"volt/4_80-volt load center transformers.
Load center transformers 25,
26, 27, 28 and 29 were oil-inslilatea and rated at 1500-kVAs each, -while load
7
center transformer 20 was a dry type, 1000-KVA unit. Safety-related loads were
supplied through 480-V buses 28 and 29 which were supplied by 4-kV buses 23-1
and 24-1, respectively.
In addition, 480-V buses 28. and 29 were interconnected
through a bus tie to enable energization from the redundant bus should the
primary power source to either bus be interrupted.
2.3.1 480 Volt System Voltage Regulation
The team reviewed the 480 volt system voltage regulation calculation 004-E-012,
Revision D, dated June 13, 1991, "MCC Bus Voltage, Dresden Units 2 and 3."
This calculation was performed to establish the motor control center bus
voltages for use in individual MDV terminal calculatior1s.
Using preliminary
plant-specific electrical load monitoring system (ELMS) loading data and a
non-degraded grid condition on the 4-kV buses, 48D-V buses 28-1, 28-3, and 29-2
were all shown to provide less than the required minimum ac~epted running
voltage (9D percent of rated voltage) required by NEMA standard MG 1-12.43.
ELMS generated voltage data was originally issued in November 1990.
The study
indicated that, with 138-kV in the switchyard, voltage levels at several
safety-related 480 volt motor terminals were in the 368 to 393 volt range,
rather than the required 414 volts. The team was concerned not only because
the licensee failed to take corrective action relative to an indication in the
calculation that design requirements for 480-Vac motors could not be met, but
also because the licensee failed to recognize the potential exacerbation of low
voltage conditions during a degraded grid condition (see Appendix A, Deficiency
Item 91-201-03).
2.3.2 Conclusions
The team determined that acceptable voltage regulation was dependent on the
results of the degraded grid calculations discussed in Section 2.2.4 of this
report.
Based on the preliminary informdtion provided by the licensee, as
discussed in Sectior1 2.2.4, the 480 volt system voltage regulation appeared to
be acceptable.
2.4 Class lE 250-Vdc and 125-Vdc Systems
The team reviewed the 250-Vdc, 125-Vac, systems including the related cabling
and penetrations. Documents reviewed were single line diagrams, schematic
diagrams, battery sizing calculations, battery test procedures, battery charger
sizing calculations, short circuit calculations, voltage drop calculations, and
protective device selection and coordination.
2.4.1 Voltage Drop Studies
The 250-Vdc system was designed to operate at a minimum of 1.81 volt per cell
(210volt - 116 cells) at end of the design duty-cycle.
Voltage drop calcula-
tions 8190-01-19-1, "250V MDV Motor Terminal Voltage," and 2D897-004-E-001-2301,
"MDV Terminal Voltage Calculations," showed that, when operated without the
battery charger and the battery at its end-of-life voltage of 210-V, there was
inadequate voltage at the termi~als of motur operated valves.
Valves with
inadequate voltage were 2-23001-14 (high pressure coolant injection (HPCI)
pump miniflow_byP-ass reli~f to torus valve), 2-2301-48 (HPCI cooling water
return to HPCI pump valve), 2-~2301-49 (-HPCI *coo-ling water return to-CST .valve).._
8
- -
.,
The team determined that the voltage at the terminals was below 175-V (70
percent of the 250-V rated voltage as specified by the licensee). However,
the licensee's subsequent preliminary calculations based on field data which
replaced certain overly conservative assumptions indicated terminal voltages
to be at approximately 71 percent of the rated voltage. The team considered
the excessive voltage drop a design wEakness.
The licensee plans further
effort in this area as part of the efforts to meet the requirements of Generic
Letter 89-10 (see Appendix B, Observatior. 91-201-02).
The 125-Vdc system alternate battery design modification involved installing an
alternate battery to supply power during the refueling outage of the unit.
During this outage, the normal battery would be taken out of service to undergo
performance or service testing.
However, the alternate battery for Unit 2 had
been installed in the HPCI building of Unit 1 resulting in a cable run of
several hundred feet, which caused an excessive voltage drop and inadequate
voltage at the distribution panel.
The team considered this a design weakness.
During the last refueling outage of Unit 2, the alternate battery was used but
adequate voltage at the panel was assured since the battery charger was in
operation.
Prior to this inspection, the licensee had completed an evaluation
of the effects of the long cable run and determined that new cables would be
installed in parallel with the existing cables so as to maintain acceptable
voltage at the distribution panel.
The licensee stated that new cable instal-
lation would take place before the next refueling outage (see Appendix B,
Observation 91-201-03).
_
2.4.2 250-Vdc and 125-Vdc System Battery Sizing
The licensee performed battery sizing calculations and installed new 250and
125-Vdc batteries about 2 years ago.
However, the licensee used design margin
factors of 1.0 tind 1.01, respectively, and an aging factor of 1.0, which was
contrary to standard industry practice using factors of 1.15 and 1.25, respec-
tively. Sizing was acceptible for present loading, but this did not allow
margin for future battery loading and battery aging.
Due to its limited
capacity- margin, the 250-Vdc and 125-Vdc batteries would become inoperable if
their capacity was determined to be below 100 percent during applicable sur-
veillance tests. The linuted capacity margin was not reflected in the existing
battery test procedures acceptance criteria, thus_ allowing a potentially
inoperable battery to go unrecognized.
The licensee intends to incorporate such
acceptance criteria into the applicable procedures (see Appendix A, Deficiency
Item 91-201-04).
2.4.3 Fuse and Breaker Coordination *
The 250-Vdc system was protected usirig molded-case circuit breakers on the
incoming and outgoing circuits. The breakers were adequately sized for the
continuous currents of the circuits. However, the coordination curves provided
in the licensee's calculations showed that the main breaker from battery #2 was
not properly coordinated with the outgoing breakers of (1) MCC #2, (2) the HPCI
turbine auxiliary oil pump connected to MCC #3A, and (3) the non-essential
turbine emergency bearing lube oil pump circuit. A fault on any of these could
trip the main breaker, thereby interrupting Unit 2 essential circuits. The
licensee took credit for the automatic depressurization, core spray and LPCI
-systems -for--assur.ing -safe. shutdown of_ the .unlt Q!Jr_ing. tne failur~ _of_ 250-Vdc
system (Ref. Calculation 7927-52-19-2
11250-Vdc Circuit Coordination,
11 Project
No. 8256-55
11250-Vdc Failure Mode and Effect Analysis"). The team considered
improper breaker coordination to be a design weakness.
For the 125-Vdc system, Unit 2 and the cross-tied buses of Unit 3 (TB#3B and TB
- 38-1) were protected with molded-case circuit breakers. Unit 3 (TB #3A) and
the cross-tied buses of Unit 2 (TB#2 and TB#2B) were protected with fuses.
Downstream circuits of both units were protected with circuit breakers.
However, the breaker and fuse coordination curves indicated that complete
coordination had not been achieved between the fuses and molded-case breakers.
Although fuse coordination was found to be satisfactory, fuse characteristics
were represented only by the total clearing curves and melting ch~racteristics
were not shown on the coordination curves. Also, complete coordination was not
achieved where breaker and fuse combinations were in series on bus 28-1.
Report No. SL-4500,
110vercurrent Protective Device Coordination Study" indicated
these design weaknesses, but that the failure of a breaker or fuse in one unit
did not affect the operability of the safety-related buses of the other unit.
The team noted that the lack of breaker coordination has been identified by the .
licensee for both the 250 and 125-Vdc systems.
The team reviewed the licensee's
planned corrective actions and found them to adequately address the desigr1
weaknesses if implemented (see Appendix B, Observation 91-201-04).
2.4.4 Conclusions
The licensee planned to take actions to correct the design weaknesses in the
de systems.
The licensee, on its own initiative, had formed a DC System Enhance-
ment Task Group to investigate the overall de system weaknesses such as
short-circuit overduty of.cirtuit breakers, circuit breaker and fuse coordina-
tion, and voltage drop problems.
The licensee expects the task group's recom-
mendations by October 1991.
In addition, the licensee intends to revise the
battery test procedures to determine battery capacity in accordance with the
load profiles.
2.5 Protective Device Coordination
Medium voltage protectivE device coordination was described in Sargent and
Lundy report SL-4500,
110vercurrent Protective Device Coordination Study,
11
Volume 1 dated March 24, 1989. This report demonstrated that adequate protec-
tive device selectivity is maintained at the 4kv level.
2.5.1 480-Vac Coordination
The licensee stated that low voltage protective device coordination was
described in Sargent and Lundy report SL-4500.
Th~ team determined that this
report was inadequatt to establish that proper coordination existed at the
480-Vac level.
In one case, the report indicated that there was a lack of
coordination between the MCC 29-8 load and feed breakers, but coordination
plots were not provided for the breakers.
The team reviewed settings and time-current curves for the MCC 29-8 feed
breaker and determined that it would not coordinate with the upstream
switchgear 29 fe-ed breaker* for faults above approximately--1200 amperes.
A
10
fault on the non-safety equipment could disable an entire safety division at
the 480v level.
However, lack of coordination would only affect one of the
redundant safety divisions.
The team verified that modifications were in progress to resolve coordination
problems.
However, since design documents for proposed modifications have not
been completed, the team could not fully evaluate the adequac,r of these
corrective actions (see Appendix A, Deficiency Item 91-201-05).
2.6 Cable Ampacity
The licensee could not provide documentation to establish that cables were
properly sized to provide sufficient ampacity.
The licensee has previously
idtntified this discrepancy and initiated a new program,
11Sargent and Lundy
Interactive Cable Engineering," (SLICE) to thermally evaluate the existing
cable installations. The team was concerned that this program may not result
in accurate cable loading and temperature rise evaluations due to the fact that
the licensee lacked field verified documentation on cable routing and cable
fill in trays, pans, and conduits. During the inspection, the licensee stated
that a pilot program to determine the accuracy of existing cable routing and
cable tray loading data will be completed before the full implementation of the
SLICE program (see Appendix A, Unresolved Item 91-201-06).
2.7 Electrical Design C~lculations
Weaknesses were identified in the area of design calculations.
In at least one
instance, inadequate calculations contributed to erroneous setting of the
degraded grid voltage relay setpoint (Section 2.2.4).
In other instances, such
as emtrgency diesel generator loading, short circuit and breaker coordination
calculations, identified weaknesses in calculation methodology and assumptions
did not result in operability concerns.
The operability criteria represent a
high threshold of safety s.ignificance against which systems and component
.
functionality are evaluated. The fact that a system or component was found to
be operable does not indicate that dtsign weaknesses or errors are inconsequen-*
tial. The team noted that the licenste had established a workgroup to improve
calculation quality. Thi . .s group has issued an initial report which addresses
the types of concerns noted by the team during this inspection. The workgroup
has proposed a plan consisting of short term and long term corrective actions
and has prepared a draft technical document to address calculation weaknesses.
The team considered the licensee's actions to be an appropriate response to
this issue, and, if fully implemented, will result in a significant improvement
in calculation quality (see Appendix B, Observation 91-201-05).
3.0 MECHANICAL DESIGN REVIEW
The team evaluated the adequacy of the design of the mechanical systems sup-
porting the EDS by sample review of the design documentation and system
walkdowns.
The supporting mechanical systems included the fuel oil storage and
transfer system, the lubricating oil system, the starting air system, the
diesel coolin9 water system, and the EDS heating, ventilating, and air condi-
tioning (HVAC) systems.
In addition, the team evaluated the power requirement~
for the m~jo~~echanical lobd~ on the diesel generators. Seismic calculations;
pipe, tank and heat- eX-changer -sizing ca lculat-ions; pump head,_ capacity ang _NPSH
calculations; pressure drop calculations, etc. for the station were not
-
available.
11
3.1
HVAC Systems Supporting the Emergency Diesel Gtnerator Rooms
The team noted that the Unit 2/3 (swing unit) em~rgency diesel generator (EOG)
room was not provided with forced ventilation during the diest:l generator
standby mode, unlike the Unit 2 and Unit 3 diesel rooms, which each received a
1000 cfm flow from the turbine building ventilation system.
As a result of the
heat loads, including room lighting and solar transmission, the Unit 2/3 EOG
room temperature may increase above the temperature rating of electrical
equipment required for the operation of the EOG.
The licensee stated that ambient temperature would be monitored in the Unit 2/3
EOG room during each shift to determine the extent of the problem and augment
the existing natural ventilation as necessary. The licensee also planned to
evaluate the need for permanent forced ventilation (see Appendix A, Unresolved
Item 91-201-07).
3.2 Mechanical/Electrical Power Conversion for Major Loads
The team reviewed the power demands of the major pump motors on the emergency
diesel generators following a loss of offsite power during LOCA conditions.
Table 8.2.3.1 of the updated final safety analyses report (UFSAR) iridicated an
estimated brake horse power (bhp) requirement for the core spray (CS) pump and
the low pressure coolant injection pump (LPCI) was 868 and 600, respectively.
However, tht team calculated that the peak loadings for the CS and the LPCI
pumps which occurred prior to runout, were 901 bhp and 649 bhp, respectively,
which were higher than the UFSAR specified values.
The team verified that the emergency diesel generators had adequate load
capacity margin to allow for the increased load demands calculated by the team.
The licensee agreed that there were several discrepancies in the tables and
figures of Section 8 of the UFSAR showing EOG loading and indicated that
revisior1s would be made (see Appendix B, Observation 91-201-06).
3.3 Emergency Diesel Generator
3.3.1 Fuel Storage Capacity
The technical specification stated that "There shall be a minimum of 10,000
gallons of diesel fuel supply on site for each diesel. The diesel fuel supply
of 10,000 gallons will supply each diesel generator with a minimum of two days
of full load operation or about four days at 1/2 load. Additional diesel fuel
can be obtained and delivered to the site within an eight hour period; thus a 2
day supply provides for adequate margin."
Calculations provided by licensee (ABB Impell Calculation No. 0591-553-001)
showed compliance with the above requirements, based on a fuel consumption rate
of 192 gallons per hour at the rated load of 2600 kW assumed in the UFSAR.
The
team expressed concern regarding an arbitrary assumption of 1-inch level loss
iri the storage tank due to vortexing.
The licensee provided further calcula-
tions (ABB Impell Calculation No. 0591-553-002) which justified this assump-
t-ion. Ttle-licensee- a-lso-provided purchase order agreements with eight separate
suppliers, any one of which can be utilized at any t;me to obtain-diesel fuel
oil within eight hours.
The team had no further concerns in this area.
12
3.3.2 Fuel Oil Quality
The fuel oil storage and day tank sample results for the period of October 1990
to June 1991 were reviewed by -the team.
In several instances during 1990
tests, the fuel oil was found to be outside the acceptable limits with respect
to sedimentation and water.
However, in more recent tests including May and
June 1991, sedimentation was within the limits recommended by the licensee*s
applicable procedure NOD-CY.6.
This procedure incorporated the acceptance
criteria for fuel oil detailed in Regulatory Guide 1.137,
11 Fuel Oil System for
Standby Diesel Gerierator,
11 Revision 1. The licensee also stated that there was
no need to measure fuel oil cloud ~oint at Dresden because the outdoor fuel oil
storage tank and transfer lines were below ground and their temperature did not
fall low enough to cause a fuel oil cloud point concern.
The team agreed.
3.3.3 Emergency Diesel Generator Oa~ Tank
The UFSAR requires that each day tank contain sufficient fuel to support the
emergency diesel gtnerator operation for lllore than four hours at the rated
lead. With a fuel corisumption rate of 192 gallons per hour assumed in the
UFSAR, the minimum fuel quantity required was 768 gallons. The team found that
the existing setting of the day tank float switch for automatically stoppirig
the transfer pUliip was too low to provide the required inventory of fuel oil in
the day tank.
The licensee found it impractical to raise the float switch to
the required level bEcause of the physical arrangement of the EOG day tank
level instrumentation.
The licensee stated that operators would maintairi 768 gallons of fuel oil
within the Unit 2 and Unit 2/3 EOG day tanks by manually overriding the fuel
oil transfer pump shutoff setpoint and raisirig the level to or above 768
gallons. This action would be performed at the end of each EOG surveillance
test.
The Unit 3 EOG fuel oil day tank fuel oil level could not be manually raised
above the EOG fuel oil transfer pump shutoff set point. However, the Unit 3
EOG fuel consumption test of June 1991 indicated a fuel consumption rate of
171.6 gallons per hour. nperators will monitor Unit 3 EOG fuel consumption
rate on a semi-annual basis to verify the Unit 3 EOG fuel consumption rate is
maintained at or below 185.75 gallons per hour, thus providing a four hour fuel
supply with the existing tank level setting (see Appendix A, Unresolved Item
91-201-08).
3.3.4 Classification of Diesel Fuel System
A portion of the fuel oil system for all three emergency diesel generators was
found to be classified as non-safety and non-seismic. This included the main
storage tank, the transfer pump, and the piping upstream of the day tank.
The
day tank and the piping and equipment downstream of the day tank were classi-
fied as safety related. The team expressed concern that a seismic event could
render the unqualified portion of the diesel fuel system for all three emergency
diesel generators inoperable.
- The licensee responded by providing a_ plan to upgrade the existing system to
safety classification by June 1992. The licensee *a lso--performed an .operability
13
determination for the system in April 1991 that showed that the diesel fuel oil
system would remain operational following the defined SSE level earthquake at
Dresden (see Appendix B, Observation 91-201-07).
The team had no further
concern in this area.
3.3.5 Emergency Diesel Generator Air Start System
The licensee was unable to provide design documentation to support the seismic
qualification of the EDG air start system which included the air receivers,
associated piping and valves.
However, the licensee performed an operability
evaluation with the help of information provided by the suppliers of the diesel
generators and re.lief valves and a seismic walkdown and evaluation by a seismic
expert. The licensee determined the air start equipment to be seismically
qualified on the basis that they were covered by the Seismic Qualification
Utilities Group (SQUG) Generic Implementation Procedures data base.
3.3.6 Conclusions
The licensee did not have sufficient design documentation for the mechanical
systems supporting the EDG.
Tht team considered this a weakness.
The* licensee
indicated that it was considering preparation of design basis documents for
various systems. A review of the EDG room heating and ventilation indicated
concern that the EDG room 2/3 temperature may exceed acceptable limits for
equipment Gualification in the EOG standby mode during hot days.
Due to
ir1strumentation problems, the team identified an unresolved item relative to
the capacity of the EOG day tanks for assuring a four-hour fuel supply, as
required.
4.0
EQUIPMENT TESTING AND SURVEILLANCE
4.1
Emergency Diesel Generator Testing
The team reviewed the emergency diesel generator (EOG) surveillance test
procedures to ensure the licensee was testing the EDGs according to the sta-
tion's Technical Specifications (TSs). The.team verified that the li~ensee was
adequately implementing TS 4.9.0.4 surveillance requirements by verifying the
emergency bus load shedding capability, the automatic start of the EDGs and
sequencing of the emergency loads onto the EDGs.
4.2 Relay and Instrument Calibration Program
The team reviewed the 4kV safety-related undervoltage, degraded voltage, and
overcurrent relay calibration program to ensure the licensee was testing the
relays according to the station's TSs or recommended vendor calibration prac-
tices. The team determined that surveillance procedure No. DOS 6600-09,
Revision 5, "Testing of ECCS Undervoltage and Degraded Voltage Results," had
the potential to set tht relays non-conservatively at the low calibration
tolerance point. The non-conservative values were caused by mathematical
rounding of the numbers.
The numbers were rounded according to standard
rounding practices. The team reviewed past calibration information and deter-
mined the Ji~ensee was maintilining the setpoints conservatively near the high
end of the calf6ration*tolerance~ The licensee promptly re.vised the procedure
with actual rather than rounded values and thereby achieved conservativ-e*
results.
14
The team review~d the calibration of the sequencing time delay relays and other
EOG iristrumentation.
The team identified two EOG speed (ES and VS) relays that
were not in the current station calibration program and could affect the fast
automatic start capability of the EOG.
Failure of the ES relay would initiate
a shutdown of the EOG in an emergency situation. Failure of the VS relay would
prevent excitation of the generator. Past successful testing of the EDGs has
demonstrated the functionality of the ES and VS relays.
The licensee stated
that the above instruments would be added to the calibration program (see
Appendix B, Observation 91-201-08).
4.3 Fuse Control
The licensee had no formal fuse replacement program in place.
Interviews with
plant personnel indicated that plant operators were presently responsible for
fuse replacement.
Replacement fuses were stored in cabinets near the control
room and were uncontrolled. At the time of the inspection a draft fuse control
procedure was in the process of being finalized.
Based on the team's findings
in this area, the licensee implemented an interim fuse control program that
established administrative controls for the storage of fuses and assured the
use of dedicated fuses in safety-related applications (see Appendix B,
Observation 91-201-09).
The team condu~ted several walkdowns and verified in all cases that the installed
fuse ratings were consistent with applicable design documents.
4.4 Conclusions
The electrical maintenance and testing was adequate.
The team identified
weaknesses in relay calibration and fuse control program.
However, the
licensee addressed these issues before the end of the inspection.
5.0 SYSTEMS WALKDOWN INSPECTION
Walkdown of electrical systems components including installation of molded case
breakers, 4kV protective relay settings, 480-V breaker settings and thermal
overloads indicated the devices were set according to applicable design docu-
ments.
In addition, the external and interna 1 material cvr.dition of EDS
equipment was very good.
The mechanical walkdowns of the diesel generators, the 250-Vdc and 125-Vdc
batteries, and selected breaker cabinets raised several seismic concerns in the
diese 1 generator a11d 125-Vdc battery rooms.
The 1 icensee provided analyses and
detailed design information in order to satisfy the team's concerns in these
areas.
In the diesel generator rooms, the team also observed stagnant oil in
the floor drains to the oil separator tank.
The licensee flushed the drains
and discovered that the oil had remained due to poor drainage caused by the
side orientation of the drain piping in relation to the collection basin.
The
licensee indicated that it would inform operators, and include, as part of
continuing training, the need to flush the drains following an oil spill to
avoid the fire hazard caused by standing oil. The team considers this resolu-
tion accepte:iLJe (see Appendix B, Observation 91-201-10).
The team also performed as-built walkdowns for the diesel- generator 2 and_2/3
subsystems (starting air, lube oil, fuel oil, ana cooling water). All drawings
accurately reflected the as-installed system configuration with only minor
15
labeling discrepancies, except for the diesel generator 2/3 lube oil system.
The drawing of this system misrepresented a valve and line connection.
The
licensee confirmed that the equipment met design requirements. A drawing
change was initiated.
6.0
ENGINEERING AND TECHNICAL SUPPORT REVIEW
The team assessed the capability and performance of the licensee's organization
to provide er1gineering and technical support (E&TS) by examining interfaces
between the licensee's technical staff organization and the functional groups
performing design reviews, surveillance, maintenance, training, and operations
activities.
6.1 Technical Staff
The licensee1s onsite organization included separate site groups for engineer-
ing support, design of modifications, maintenance, quality assurance, and
training. The corporate office included a nuclear engineering department that
assisted primarily in major modificat~ons. The technical staff provided the
onsite engineering support primarily through its system engineers.
The Techni-
cal Staff was divided into seven groups including safety systems, auxiliary
systems, and nuclear engineering. The team noted that the site technical
departments were adequately staffed.
The interfaces between the Technical Staff and the various onsite and offsite
organizations appeared effective, although, largely informal. Site personnel
indicated that interactions with the Technical Staff group had improved over
the last several years. System engineers were more inclined to accompany crews
during maintt11ance activities. The licensee implemented an effective and
formal mechanism to ensure information flow between the Maintenance and Techni-
cal Staff organizations called the Problem Analysis Data Sheets (PADS).
Other regular interactions include those between Technical Staff engineers and
other departments on deviation reports, root cause analysis, and operability
determinations.
6.2 Self Assessments
The team evaluated the licensee's self assessment program including their own
assessn1ents of the Dresden electrical distribution system.
The team found that
limited formal CJr programmatic assessments existed.
The only detailed assess-
ment the team found was a functional inspection of the Unit 3 emergency diesel
generator conducted in mid-1987.
The scope of this assessment included the 125
volt battery, the 4160 and 480-Vac buses, and the diesel generator room venti-
lation.
~ithin its scope, the assessment appeared comprehensive.
Over 450
con~erns were identified which were evaluated, had corrective actions estab-
lished, and were tracked to closure. At the time of the inspection, only four
open items remained.
There were no formal assessments made of the design of the Dresden electrical
- distribution syste!ll. __ The license had, in the course of developing modifications
and tracking programs such as the Electr-ical .Loag f1onit~ring System (ELMS) and
16
SLICE, identified a number of design issues such as lack of
circuit breaker coordination and inadequate short circuit interrupting capacity
of certain circuit breakers.
However, the response to these assessments did
not include timely and effectiv~ resolution (see Appendix B, Observation
91-201-11).
6.3 Root Cause Analysis and Corrective Action Program
There were a number of we~knesses regarding the root cause analysis and correc-
tive action programs.
The licensee's program was described in OAP 02-08, "Deviation Reporting,"
Revision 8, dated March 1991.
However, the procedure did not contain direction
on how to perform a root cause anal;*sis. The inconsistent report format of
existing deviation investigation and personnel error investigation reports
contributed to a lack of clarity regarding issues. Root causes were sometimes
vague, contributing causes were not always clearly stated, and inadequate
reconunendations were presented in light of the facts.
The licensee has recognized these weaknesses ifi its processes and planned to
implement an integrated reporting program by the end of 1991.
The new program
would incorporate all of the licensee's event reporting and investigation
processes ir1to a single procedure.
The procedure as drafted was based on the
Institute of Nuclear Power Operations Human Performance Evaluation System
methodology.
This was supplemented by a checklist approach to aid identifica-
tion of component failure causes (see Appendix B, Observation 91-201-12).
The team also reviewed the status of thirty-nine corrective actions identified
in the root cause analysis reports and identified three minor instances where
the operations department failed to initiate the corrective actions identified
in the reports. The team noted that the corrective action process did not
include: a regular reporting mechanism to inform plant management of such issues
as overdue action items. This lack of routine status reporting to management
deprived managers of an important accountability tool to ensure that actions
art appropriately completed by responsible individuals.
6.4 Design Changes and Modifications
The team determined that the licensee's procedures controlling modification
work and related testing were generally comprehensive but their implementation
was inadequate.
The team reviewed four*modification packages completed within
the past six year5 and found deficiencie5 with three.
The deficiencies involved failing to specify required' testing and lack of
documented evidence that testing accomplished verification of equipment opera-
bility. These examples generally involved testir.g of contacts, breakers and
relays.
In all cases, the team reviewed schematic and logic diagrams to
independently verify that the* testing deficiencies did not compromise equipment
operability. However, the licensee plans to (1) retest the affected circuits
and (2) provide additional training in the implementation of the modification
-program (see App_endix A, Deficiency Item 91-201-09).
17
6.5 Conclusions
The evaluation of self-assessment of the electrical distribution system provided
mixed results.
Formal analysis of design and of components other than the
Unit 3 diesel generator has not occurred, and the informal assessments which
identified problems did not always include prompt resoluticm.
Good progress
was being made in the trending of important electrical component parameters for
line management assessment.
An attitude conducive to personnel continually
assessing their own actions and plant status was reinforced, which contributed
to an overa 11 encuuragement of self-assessment throughout the organization.
The root cause analysis program had prograrranatic and in1plementation weaknesses.
However, the new integrated reporting program when fully implemented should
address these issues.
The 'omponents and systems inspected were installed ir1 accordance with the
design requirements.
However, post-modification testing deficiencies were
identified relative to the implementing requirements of Procedure OAP 5-1,
Form 5-lf and verifying operability of breakers, contacts, and relays.
7.0 EXIT MEETING
The team conducted an exit meeting of August 9, 1991 at the Dresden Nuclear
Power Station to sunvnarize the scope and findings of the inspection.
NRC
management from NRR and Region III and licensee representatives who attended
this meeting are identified in Appendix B of this report. The team discussed
licensee actions on major issues. The licensee did not identify any documents
or processes as proprietary.
18
.,
APPENDIX A
Su111nary of Inspection Findings
DEFICIENCY 91-201-01
FINDING TITLE: 4-kv Circuit Breaker Inadequate Short Circuit Capacity
(Section 2.2.1)
DESCRIPTION OF CONDITION:
The teQm determined that several 350 MVA and 250 MVA circuit breakers in the
4-kv system (including safety-related breakers on buses 23 and 24) could
receive fault curr~nts in excess of their maximum interrupting rating.
In
addition, some safoty-related 250 MVA and non-safety related 350 MVA breakers
could receive fault currents in excess of their momentary ratings. Safety
related 250 MVA breakers could experience fault cu~rents as high as 114 percent
of their interrupting ratings and 118.4 percent of their momentary ratings.
Failure of certain ov~rdutied breakers to function properly could result in a
long-term loss of the preferred power source to a safety bus.
However, a
safety eva luat ior1 provided by the licensee cone luded that, because of redur1-
dancy and availability of emergency power sources, operability of ESF/loads
could be n1aintained.
The team noted that the overduty conditions described above had been identified
by the licensee on several occasions as early as 1982 and corrective actions
had not yet been initiated. The licensee has submitted a preliminary study of
proposed reconunended actions which would, if implemented, resolve the overduty
problems by 1996.
REQUIREMENTS:
Dresden FSAR section 8.2.2.2 which states, "All protective circuit breakers are
sized according to standard electrical industry practice where maximum inter-
rupting capabilities of the circuit breakers exceed the available line to lirie
or 3 phase short circuit current taking into account the impedances of the
generator, transformers and other electrical system components."
10 CFR 50 Appendix B, Criterion XVI, "Corrective Action," requires, in p~rt,
that measures be established to assure conditions adverse to quality, such as
deficiencies and nonconformances, are promptly identified and corrected.
REFERENCES:
Calcufotion 8445-01-EAD-1 dated 01-31-90, Cales for Electrical Auxiliary
System.
A-1
DEFICIENCY ITEM 91-201-02
FINDING TITLE: Degraded Grid Undervoltage Protection
(Section 2.2.3)
DESCRIPTION OF CONDITION:
Based on the requirements of the Branch Technical Position PSB-1 (below), the
licensee should have determined the minimum acceptable starting and running
terminal voltages required for acceptable safety-related device operation.
Using these as input, the most critical, or bounding voltage requirements and
11 distribution system loading should have been considered in estab-
1 ishing the second level undervoltage protection setpoints. The licensee's
setpoint calculation, dated 2/21/84, used an oversimplified methodology and
unverified assumptions, and apparently had not been checked or received. an
independent design review.
Second level undervoltage protection was added as a
design change to both Units 2 and 3, but there was no indication that the
starting and/or running voltages of safety-related devices had been addressed.
As a result of the team's above concern, the licensee performed preliminary
calculation NED-E-IC-0050, Revision 0, dated July 22, 1991, "Adequacy of EOG
Cooling Water Pump 2 Under Degraded Voltage Conditions," to determine the
required voltage levels on 4160 volt bus 29-1 to support starting and running
of the assumed "worst-case" motor load. This calculation indicated that 3960
volts was required on 4160 volt bus 29-1 for "worst-case" motor starting and
3850 volts for "worst-case" motor running conditions. Thus the trip setting of
the second level undervoltage relay of 3708 volts to 3784 volts, as determined
by the.licensee's February 21, 1984 calculation, appeared inadequate.
The
licensee advised the team that the target date was September 30, 1991 for
formalizing this calculation, irrcluding supporting calculations and analysis as
required to demonstrate that it is the bounding case. Similar calculations
analyzing 4160 volt buses 28-1, 38-1 and 39-1 were targeted for November 18,
1991.
.
REQUIREMENTS:
Section III, "De:sign Control" of 10CFR50, Appendix B, requires, in part, that
licensees establish design control measures for verifying or checking the
adequacy of the design and changes to the design.
Branch Technical Position PSB-1 dated July 1981, which addressed degraded grid
voltage protectfori, required that second level voltage protection be provided
for the unsite power system.
The document requires that selection of
undervoltoge and time delay setpoints shall be determirred from an analysis of
the voltage requirements of the Class lE loads at all onsite system distribu-
tion levels.
REFERENCES:
Calculation NED-E-EIC-0050, "Adequacy of DG Cooling Water Pump 2 Under Degraded
- voltage Conditiv.r1s,
11 dated 7/24/91.
A-2
DEFICIENCY ITEM 91-201-03
FINDING TITLE: Corrective Actions and Reporting of Defects
(Section 2.3.1)
DISCUSSION:
The Dresden Unit 2 "ELMS Running Voltage Summary,
11 dated November 9, 1990,
which was used as a reference for a lattr calculation 004-E-012, Revision 0,
dated 6/13/91, "MCC Bus Voltages, Dresden Units 2 and 3,
11 indicated running or
steady-state voltages for the "worst-case," non-degraded grid condition of
408.5 volts, 380.1 volts and 406.1 volts on the safet)*-related 480 volt motor
control center buses 28-1, 28-3 and 29-2, respectively. Based on the
. licensee's assumed 12 volt drop between the motor control center buses and
motors, as used in their calculation used to determine the second level
undervoltuge protection relay settings, less than 90 percent of motor nameplate
volta~e would have been available at motor terminals.
states that acceptable operation of AC motors can not be assured with less than
90 percent of rated voltage at their terminals. Licensee engineering and
operations personnel were aware of the potential low voltage condition that may
render safety related equipment inoperable during an accident.
However, the
licensee was unable to identify to the team a nonconformance report, or docu-
mentation of corrective actions that evaluated this anomaly.
REQUIREMENTS:
Section XVI, "Corrective Action" of 10 CFR 50, Appendix B requires, in part,
that licensees e~tablish measures to assure that conditions .adverse to q~ality,
such as deficiencies and nonconformances, are promptly identified and
corrected.
10 CFR 50.21 requires, in part, that ~ li~ensee's respofisible officer, who
obtains information reasonably indicating that the facility contains defects
which could create a safety hazard, inunediately notify the USNRC of the
condition.
REFERENCES:
1. Dresden Unit 2 "ELMS Running Voltage Sununary,
11 dated November 1990
2.
480 V System Voltage Regulation Calculation 004-E002, Revision 0,
June 13, 1991.
A-3
DEFICIENCY ITEM 91-201-04
FINDING TITLE:
Inadequate Acceptance Criteria for Battery Survei 1 lance
(Section 2.4.2)
DESCRIPTION OF CONDITION:
The 250 and 125 Vdc battery s1z1ng calculations had been performed and new
batteries had betn installed about 2 years ago.
The team noted that the
calculations were performed with design margin factors of 1.0 and 1.01, respec-
tively, and an aging factor of 1.0, contrary to standard factors of 1.15 for
design margin and 1.25 for aging. Sizing was acct:ptable for present loading,
but this did not allow margin for future battery loading and aging.
Due to the limited margin, the batteries would be inoperable if their capacity
was be low 100 perci:nt.
However, tht:! team nlited that the battery test proce-
dures did not reflect this in the acceptance criteria. Given this situation,
surveillance tests may not identify conditions whert the battery is at lower
capacity than that required for the operation of the engineered safety systems.
REQUIREMENTS:
10 CFR 50, Appendix B, Criterion XI, requires that test procedures inccrporate
acceptance limits.
REFERENCES:
1.
Calculation 7056-00-19-4
11250 V de Load Profilt:
2.
Calculation 7056-00-19-5 "Load Estimation of 125 V de Buses".
3.
Test Procedures SP90-10-119, DEP 8300-19 and DEP 8300-20.
4.
IEEE-485, "Recommended Practice for Sizing Large Lead Storage
Batteries ***
11
A-4
DEFICIENCY ITEM 91-201-05
FINDING TITLE:
Lack of 480v Coordination
(Section 2.5.1)
DESCRIPTION OF CONDITION:
The team determined that Report SL-4500 dated March 24, 1989 was inadequate to
establish that proper coordination exists, and that in fact demonstrated that
at several points coordination did not exist. The lack of coordination included
devices intended to isolate non-safety circuits from their safety-related
supply.
Report weaknesses included the following:
1.
The report was not*a controlled design document and it did not show
coordination curve plots for all devices requiring coordination. For
example, as-built plots were not provided for load breakers at MCC's
29-3, 29-5, and 29-6.
2.
Important information necessary to show adequate coordination with equip-
ment characteristics was omitted from the coordination curve plots includ-
ing motor damage curves, maximum inrush current, full load currents,
locked.rotor current and cable thermal limits.
3.
Ttit maximum fault current shown on coordination plots was 15,500A. This
value is below the fault currents determined in calculation 6558-EAD-3 of
16,329A for bus 28 and 16,078A for bus 29.
In addition, this value does
not include motor contributions from the 480v buses, which may affect
coordination for bus tie breakers and MCC load breakers.
In addition to the above weaknesses, the report revealed that there was a loss
of coordination at several points on the system.
Examples of devices that are
not coordinated include:
-Switchgear 28 and 29 fe~d breakers and the bus tie breakers.
-MCC feed and MCC load circuit breakers.
The team prepared coordination plots for the MCC 29-8 feed breaker and deter-
mined that it would riot coordinate with the upstream Switchgear 29 feed breaker
for faults above approximately 12,000 A.
A fault on the non-safety equipment
could disable an entire safety division at the 480v level. Because of redun-
dant safety divisions, these conditions do not present an operability concern.
However, they represent a design weakness which could diminish the overall
capab i 1 i ty of .the EDS.
Th~ team not~d that modifications were in progress to resolve coordination
problems.
However, since design ducuments for proposed modifications have not
been completed, the team could not full.>* evaluate the adequacy of these correc-
tive actiuns. Corrective actions ar~ schedul~d to be completed by 9-94.
A-5
REQUIREMENTS:
10 CFR 50, Appendix B, Criterion III, "Design Control," requires, in part, that
design control measures be provided for verifying or checking the adequacy of
design.
10 CFR 50, Appendix B, Criterion XVI, "Corrective Action," requires, in part,
that measures be established to assure that conditions adverse to quality, such
as deficiencies and nonconformances, are promptly identified and corrected.
REFERENCES:
Report SL-4500, Overcurrent Protective Device Coordination Study, Dresden
Station U11its 2 and 3, dated March 24, 1989.
Calculation 6558-EAD-3, dated 08-10-82, Cales for Short Circuit at 480v Level.
A-6
UNRESOLVED ITEM 91-201-06
FINDING TITLE:
Adequacy of cable ampacity not established
(Sectio11 2.6)
DESCRIPTION OF CONDITION:
The licensee was unable to provide docuruentation to establish that cables were
properly sized to provide sufficient ampac i ty. Tht licensee stated that cable
sizins was established using various architect engineer (AE) standards.
The AE
standards were based cm industry standards; however, the particular industry
standards used to develop the AE standards were not identified.
As a result,
the team could not effectively evaluate cable sizing and cable raceway fill
requirements.
The licensee stated that ampacity is being evaluated using the Sargent anci
Lundy Inttractive Cable Engineering (SLICE) program.
The approach involves
performing a thermal analysis of actual installed configurations to determine
adequacy of cable ampacity.
However, since this approach involves analyzing
actual installed configurations, the validity of the results relies on having
complett:! and accurate information regarding cable .routing.
Input to the
program was based on cable tabs" which were the routing instructions provided
to the installers. The l i ctn see did not have a program to verify the accuracy
of routing instructions or their correct implementation.
The licensee has
agreed to perform a pilot study to verify cable routings to determine if
further verification is warranted.
If cable ampacity is not adequatt:!, allowable conductor temperatures could be
exceeded. This could, in time, degrade the insulation and its ability to
withstand accider1t conditions.
REQUIREMENTS:
10 CFR 50, Appendix B, Crittrion Ill, Design Control," requires, in part,
design control measures be provided for verifying or checking the adequacy of
design.
10 CFR 50, Appendix B, Criterion XVI, "Corrective Action," requires, in part,
that measures be established to assure conditions adverse to quality, such as
deficiencies and nonconformances, *are promptly identified and corrected.
REFERENCES:
Sargent and Lundy Interactive Cable Engineering (SLICE) program.
A-7
UNRESOLVED ITEM 91-201-07
FINDI~G TITLE:
High Unit 2/3 EOG Room Temperature
{Section 3.1)
DESCRIPTION OF CONDITION:
The team found the Unit 2/3 EOG room to be excessively hot during two walkdowns
in the week of July 22, 1991.
The team was concerned regarding the detrimental
effect of very high room temperature on electrical equipment and personnel.
The electrical relays for the EOG generator and exciter were rated for a
maximum temperature of 122°F.
The team noted that Unit 2/3 diesel room was not provided with any forced
ventilation during stand~ mode, unlike the Unit 2 and Unit 3 diesel rooms each
of which received a 1,000 cfm flow from the turbine building ventilatio~
system.
Due to heating loads, including room lighting arid solar transmission,
the Unit 2/3 EOG room temperature could rise above 122°F in hot days during
standby mode.
The cabinets housing the relays could reach even higher tempera-
ture than the room temperature.
The licensee agreed to monitor the room temperature during each shift, provide
ventilation as appropriate to assure continued operability should the tempera-
ture exceed 122°F, and evaluate the need for permanent forced ventilation.
REQUIREMENTS:
10 CFR 50, Appendix B, Criterion III, requires that measures shall be estab-
lished for the review of suitability of equipment that are essential to the
safety related functions of systems.
REFERENCES:
N~
A-8
UNRESOLVED ITEM 91-201-08
FINDING TITLE:
Insufficient Fuel in EOG Day Tanks
(St:ction 3.3.3)
DESCRIPTION OF CONDITION:
The UFSAR required that each day tank contain sufficient fuel to support the
emergency diesel generator opEration for more than four ~ours at the rated
load.
The team nuted that, with the UFSAR identified fuel consumption rate of
192 gallons per hour, the minimum fuel quantity required in the EOG day tanks
was 768 gallons.
The team found that the existing setting of the day tank
float switch for the auto stop of the transfer pump would limit the fuel
inventory in' the day tanks to approximately 743 gallons. The licensee found it
impractical to raise the float switch to the required level due to the existing
physical arrangement of the EOG day tank level instrumentation.
The licensee stated that it would take the following actions to assure a fuel
oil supply of four hours in the EOG day tanks.
The operators would maintain
768 gallons of fuel oil within the Unit 2 and Unit-2/3 EOG day tanks by manually
overriding the fuel oil transfer pump shutoff setpoint and raising the level
at or above 768 gallons. Operators would perform this action at the end of EOG
surveillance tests. This action would be taken provided the day tank high
levt: 1 a la rm could be set above the 768 gallon level. If the high level a la rm
could not be set in this position, Dresden station would utilize the same
method for assuring a 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> day tank fuel oil capacity as described below for
the Unit 3 EOG.
The Unit 3 EOG fuel oil day tank fuel oil level could not be manually raised
above the EOG fuel oil transfer pump shutoff setpoint. Dtesden station would
maintain the Unit 3 EOG fuel day tank level at the existing EOG fuel oil
transfer pump shutdown setpoint of 42.5 inches, corresponding to 743 gallons of
useable fuel oil, or a higher level if physically achievable.
The 743 gallons
of usable fuel oil could provide a four hour fuel oil supply at a fuel consump-
tion. rate of 185.75 gallons/hour.
The Unit 3 EOG fuel consumption test of June
1991 indicated a fuel consumption rate .of 171.6 gallons/hour. Dresden will
monitor the Unit 3 EOG fuel consumption rate on a semi-annual basis to verify
that it is maintained at or below 185.75 gallons/hour.
The licensee also plan~ to evaluate EOG fuel oil day tank level instrumentation
design changes as a potential long term action to assure automatic level
control of the day tanks.
REQUIREMENTS:
UFSAR Section 8.2.3.1, diesel generator fuel supply requirement.
REFERENCES:
l.
Surv~i]lance procedure DOS 6600-1, Revision 22.
A-9
'
'
DEFICIENCY ITEM 91-201-09
FINDING TITLE:
Inadequate Post Modification Testing
(Section 6.4)
DESCRIPTION OF CONDITION~
The team determined that the licensee's procedures controlling modification
.work and related testing were generally comprehensive.
However, the team
reviewed four modification packages completed within the last six years, and
identified deficiencies for post-modification function~l testing in three of
the four packages.
Modification Ml2-2-88-05:
Replace Feed Brtakers on MCC 28/29-7
Control relay 2871/a, contact Tl/Ml, should have been verified to trip breaker
No. 2971 during the performance of Test Procedure SP 89-1-4, Revision 0, "LPCI
Swing Bus.
11
Procedure OAP 5-1, "Plant Design Change Program," form 5-lF,
"Modification Testing Guidelines and Modifications Testing Committee Approval,"
was appruved for Test SP 89-1-4. It required that a construction test be
performed to written instructions including acceptance criteria and that a
modification test demonstrate the modified components function properly and do
not adversely affect the interrelationship with other components.
The follow-
ing discussion indicates non-compliance with these guidelines and lack of
documentary evidence that the contact/breaker interaction was tested.
Constructivn Test Procedures No. 7, Revisiori 1, "Miscellaneous
Breakers/Contactors,
11 and No. 19, Revision 1, "Control Circuits," were used by
construction personnel to check out the modification.
The procedures required
that all devices be functionally checked per schematic diagrams by v*erifying
that individual device contacts would make up.
However, the station traveler
did not contain documented evidence that specific circuit checkout.criteria
were met, other than an initial by the operator and Quality Assurance that the
constructivn procedures were performed.
The team concluded that this type of
documentation did not provide satisfactory assurance that the contact/breaker
operability was verified *.
Station Nuclear Engineering Department (SNED) specified that the test and
acceptance criteria for this modification. However, the testing of CR 2871/a
interlock contact Tl/Ml was not specified.
The team noted that a technical staff engineer assigned to document the
post-modifico.tion test failed to identify the omission of the CR 2871/a con-
tact. This could easily have been identified by checkirig modification bounda-
ries on the schematics against test procedure boundaries.
~:edification Ml2-2/3-82-21:
Bypass of Underfrequency Relay in Auto Start
Circuitry and Diesel Generator Auto Start During a Loss of Onsite Power
The -team determjne( that Ml2-2/3-82-21 functional test results were inadequately
documentt!d and evaluated-to assure. th~t the requirements for procedure steps
8E and 14E (specifying breaker position) had been satisfieg. Additionally,
there was no documented evidence to demonstrate the independent bperation-of ____ -~
A-10
---
.*.
- .
contacts 152-2303/b (5/5T), 152-2311/b (5/5T), 152-3312/b (5/5T), and.
152-3303/b (5/5T).
Modification Ml2-2-80-34:
Non-Synchronc;,us Closure Logic Installed in Diesel
Generator Breaker Control Circuits and Addition of Second Level Undervoltage
Relays
The team determined that there were no documented test rtsults to demonstrate
(1) the operation of the non-synchronous contact installed in the DG close
permissive circuit c;,n breaker Nos. 152-2333 and 152-242~ and (2) independent
action of undervoltage relay contacts 127-3-823-1 (11/12), 127-4-823-1 (5/6),
127-3-824-1 (11/12) arid 127-4-824-1 (5/6) to assure energization of relays
TDR-24-1 and 427Yl-24-l.
The licensee plans to rettst the affected circuit described above and provide
additional training in the implementation of the training program.
REQUIREMENTS:
10 CFR Part 50, Appendix B, Criterion V, "Instructions, Procedures, and Draw-
ings," states, in part, that activities affecting quality shall be accomplished
in accordance with these instructior1s, procedures, and drawings.
REFERENCES:
1.
DAP 05-01, Rtvision 19, Plant Modification Program
2.
OAP 07/04, Revision 14, 10 CFR 50.59, Control of Temporary System
A lteratior1s
3.
OAP 10-02, Revision 4, 10 CFR 50.59, Review Screening and Safety
Evaluations
4.
Construction Test Procedure No. 7, Revision 1, Miscellaneous
Brtakers/Contactors
5.
Construction Test Procedure No. 19, Revision 1, Control Circuits
A-11
--
APPENDIX B
Summary of Observations
- 1)
Observation 91-201-01, "Overcurrent Protection for Unit Substation
Transformer", Section 2.2.2
2)
Observation 91-201-02, "Voltage Available at MDV, Section 2.4.1
3)
Obstrvation 91-201-03, "Voltage Drop in Power Cables for Alternate
Battery", Section 2.4.1
4)
Observation 91-201-04, "DC System Fuse and Breaker Coordination", Section
2.4.3
5)
Observatior1 91-201-05, "Quality of Electrical Design Calculations",
Section 2.7
6)
Observation 91-201-06, "Discrepancies in EOG Loading as described in
UFSAR", Section 3.2
7)
Observu.tion 91-201-07, "Seismic Qualification of Diesel Fuel Oi.l System",
Section 3.3.4
8}
Observation 91-201-08, *"Calibration of EOG Speed Relays", Section 4.2
9)
Observation 91-201-09, "Fuse Control," Section 4.3
10) Observation 91-201-10, "Oil Separator Tank Floor Drains", Section 5.0
11) Observation 91-201-11, "Response to Breaker Coordination and Short
Circuit Interrupting Capacity Concerns", Section 6.2 *
12) Observation 91-201-12, "Routine Status Reporting of Overdue Action
Items", Section 6.3.
E-1
- -----
APPENDIX C
EXIT MEETING ATTENDEES
Commonwea 1th Edi svn Company Personnel
Briley, S. - Technical Staff Engineer
Brunner, J. D. - Technical Staff Support Superintendent, Production Services
Christel, B. - Assistant Technical Staff Support
DelGeorge, L. 0. - Assistant Vice President, Engineering and Construction
Eenigenburg, E. D. - Station Manager
Galle, D. - Vice President, BWR Operations
Gates, J. - Assistant Technical Staff Supervisor
Grier, C. - En9ineer, BWRSD
Hill, H. L. - Regulatory Assurance, ENC
Jurecki, J. 0. - Staff Engineer
Lawson, S. - Safety Systems Group Leader, Technical Staff
Lowenstein, D. - Regulatory Assurance Analyst
Manning, P. F.-- Director, Safety Assessment Department
Massin, H. - Superintendent, BWRSD
Morgan, W. E. - Nuclear Operations
O'Brien, T. - Nuclear Engineering, Mechanical/Structural Design Group
Pack, M. B. - Systems Engineer
Radtke, R. - Compliance Engineer, Nuclear Licensing
Reed, M. L. - Superintendent, E/I&C
Smith, G. C. - Assistant Superintend~nt of Operations
Steckhan, E. - Nuclear Quality Programs Engineer
Strait, M. - Technical Staff Supervisor
Uhlir, K. - Senior Engineer
Ungeran, R. J. - Corporate MDV Coordinator
Van Pelt, D. - Assistant Superintendent, Maintenance
Viehl, B. - Site Engineering Supervisor
Wagner, G. P. - Nuclear Engineer Manager
Persons Invited by the Licensee
Dejai, B. D. - Electrical Engineer, S&L
Francis, W. G. - Electrical Supervisor, Bechtel
Mazza, R. J. - Project Director, S&L
Morris, G. - Principal Engineer, ERCE
Schiavon, R. M. - Sr. Electrical Engineer, S&L
Schwartz, W. G. - Assistant Manager, Electrical Department, S&L
White, T~ S. - Senior Engineer, ERCE
Nuclear Regulatory Conunission Personnel
Butler, D. S. - Reactor Inspector, Riii
Gardner, R. - Chief, P larit Syster.is, RII I
Hal~er, J. T. -
Consult~nt
lnibro, E. v:---
Chief,--Speci~l Inspection Branch, NRR
Kol tay, P. S. - T ~am Leader, NRR - - - -
C-1
Letlananda, S. - Consultant
Martin, T. 0. - Deputy Director, DRS, Rill
Miller, M. A. - Operations Engineer, NRR
Norkin, D. P. - Section Chief, ORIS, NRR
Padhi, D. N. - Consultant
Peck, M. S. - Resident Inspector
Rogers, w. G. - Senior Resident Inspector
Scott, W. H. - Rtactor Inspector, Riil
Skinner, G. - Consultant
Tran, L. N. - Reactor Engineer, NRR
C-2