ML17174B101
| ML17174B101 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/20/1991 |
| From: | Darrin Butler, Gardner R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML17174B098 | List: |
| References | |
| 50-237-91-38, 50-249-91-42, NUDOCS 9201210106 | |
| Download: ML17174B101 (10) | |
See also: IR 05000237/1991038
Text
- .
U .* S. NUCLEAR REGULATORY COMMISSION*
REGION III
Reports No. 50-237/91038 (DRS); No.
50-~49/91042 (DRS).
Docket Nos. 50-237; 50~249
Licenses No.
DPR~l9; No. DPR-25
Licensee:
Commonwealth Edison Company*
Opus West III
1400 Opus Place
Downers Grove, IL
60515
Facility Name:
_,
Dresden Nuclear Power Station
Units 2 and 3
In~pection At:
Morris, IL
60450
Inspection Conducted:
December 2-*6, 19 91
Inspector:
Appr9ved By:
.~i\\./~ryi~k
D. s. Butler
~I/\\.~~~
R~ N. Gardner, Chief
Plant Systems S~ction
Inspection summary
Id-/;;..n /'f /
Date
Date
Inspection 6n December 2-6, 1991 (Reports No. 50-237/9lb38(DRS);
No. 50-249/91042CDRS))
Areas Inspected:
Routine, announced inspection to follow up
previously id,ntif ied Electrical Distribution Safety Functional
Inspection (EDSFI) concerns (Temporary Instruction 25111).
Results:
In the area that ~as* reviewed~ the following items were
identified:
one violation for failure to include appropriate
acceptance ciiteria in post modification test procedures
.(Paragraph 2. i.); one deviation* from FSAR commitments (Paragraph
2.a.); four unresolved ite~s (Paragraphs 2.b., 2.c~, 2.e., and
2.f.); and three open items (Par~graphs 2.b., 2.g., and 3.0.).
DETAILS
1.
Persons contacted
2.
Commonwealth Edison Company CCECo)
- C. Schroeder, ~tation Manager .
- L. Gerner,- Superintendent, Technical Services
- J. Kotowski, Superintendent, Production
- G~ smith, Assistant Superintend~nt, Operations
- D. VanPelt, Assistant Superintendent, Maintenance
- K. Peterman, Supervisor, Regulatory Assurance
B *. Viehl, Supervisor, NED
J. Harrington; Nuclear Quality Programs (NQP)
- J. Gates, Assistant Supervisor, Technical Staff
- R. Stachniak, Performance Improvement (PI)
- K. Deck, Orisite N~clear Safety
w. Morgan, Nuclear Operations
- D. Karsala, PI
- T. Gallaher, NQP
- . *R. R~lph, Technicai Staff
- B. Adams, Regulatory'Assurance (RA)
- D. Lowenstein, RA
R. Falb(), RA
Illinois Department of Nuclear Safety CIDNS)
- R. Zuffa, Illinois Resident Inspector
U.
s~ Nuclear Regulatory Commission CNRC)
- R.
G~rdrier, Chief, Plant systems Section
- *W~ Rogers, Senior Resident Inspector
- M. Peck, Resident Inspector
- D. Liao, Reactor Engineer
The NRC inspector also contacted and inter-Viewed other*
licensee personnel.
- Denotes those present at the exit interview on* December*6,
1991.
Licensee Action on Previous Inspection Findings
The purpose of this inspection was to follow up deficiencies
previously identified in Electrical Distribution System
Functional Inspection (EDSFI) Reports No.* 50-237/91201 and
_No. 50-249/91201.
A numb~r of the EDSFI concerns will be
closed in this report based on additional inspections
conducted and a review of licensee commitments documented in
the licensee's November 4, 1991, response to the EDSFI
2
. - ----- --- ---~--*-** -
report.
The remaining concerns will be assigned a tracki~g
number associated with this report *. The attached appendix
contains the complete list of items discussed in this report
and their status.
.
.
.
a.
Deficiency No.* 91-2.01-01: *Inadequate Short Circuit
Capacity of 4kV Circuit Breakers
The EDSFI team deterinined that 350MVA and 250MVA
circuit breakers, including safety related breakers on
bus Nos. 23 and 24, in the 4kV system could experience
fault currents up to 114 percent (overduty) of their
maximum interrupting rating.
These conditions are*
. .
contrary to Final Safety Analysis Report (FSAR)
sect~oh
.
.
/. .
.
.
a.2.2.2 which states, "All protective circuit breakers
are sized according to* standard electrical industry
practiGe.where maximum interrupting capability of the
circuit b*reakers exceed the available 1 ine to 1 ine or 3
phase short circuit .current taking into accourit the
impedances of the generator, transformers and other
electrical system componerits.J*
The inspector*
considered the overduty condition relative to maximum
breaker in~erru~ting ratings to be.a deviation
(237/91038-0l(DRS); 249/91042-0i(DRS)) from the
commitment made in FSAR Section a. 2. 2 .* 2.
The licensee performed a safety evaiuation and
concluded, based on redundancy and availability of ,
emergency power sources; that operability of emergency
safety feature (ESF) loads could be maintained.
The
EDS FI team concur.red with the licensee Is determination ...
b.
Deficienc~ No. 91-201-02:
Inadequate Calculation to
Determine Deciraded Grid Relay Trip Setpoint
TheEDSFI team determined that the.degraded voltage
setpoint may be set too low to adeql.lately protect
.safety related motors*during a LOCA concurrent with a
degraded grid voltage that hovers above the degraded
voltage relay .setpoint.
The licensee committed in their November 4, 1991;
response to the Diesden EDSFl repoit to complete the
degraded voltage calculations for bbth units by
J<inuary 31, 1992.
The safety significance of this item
will be determined following NRC review of the
calculations.
This is considered an unresolved item
(231/91038-02(DRS); 249/91042-02(DRS)).
.
.
The licensee reported the degraded voltage deficiency
in Licensee Event Report (LER) No.91-021.
Until the
degraded voltage calculations are completed and a
3
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~--:---------.~ -~ :
proper setpoint has _been established, the licensee has
implemented compensatory measures to take manual
actions to ehsure safety related e~uipment will start
and run.
This LER will remain open (237/91021-LL)
p~nding further NRC.review of de~raded voltage concerns
at Dresden.
c~
Deficiency No. 91-201-03:
Fiilure to Take.Prompt
Corrective Action.
The EDSFI team identified that the licensee was aware
of the potential for degraded voltage condi~ions on
safety related motor control centers (MCCs) Nos. 28-1,
28-3, and 29-2.
This was documented in Dresden Unit 2
. .
_,
.
.
"ELMS Running Voltage Summary," da_ted November 9, 1990.
However, the licensee was unable to identify to the
EDS FI team. a nonconformance report, *or documentation of
corrective actions that eyaluated this deficiency.
The
safety significance of ~this item ~ill be determined
following NRC review of the degraded voltage
calculations to be completed January 31, 1992.
This is
considered an unresolved item (237/91038~b3(DRS);
i49/9102~03(DRS)).
.
.
d.
Deficiency 91-201-04:
Inadequate Acceptance Criteria*
for Battery Surveillance
The EDSFI team was coricerned that t~e 250 Vdc and 125
Vdc battery performance test surveillance procedures
did not contain adequate acceptance criteria to
determine the.batteries were inoperable if their
capacity was below 100 percent.
The team noted that
the 250 Vdc and 125 Vdc battery sizing calculations
were performed with design margin factors of 1.0 and
1.01, respectively, and an aging factor of 1.0.
I~EE
485 recommends using a design margin of 1 .. 15 and 1. 25
for aging.
The 250 Vdc battery sizing calculation indicate~ a
total r.emaining margin of 16. 6 percent between* the
actual number of positi~e plates provided in the
battery (10 plates) and the required number of positive.
plates to meet the design requirement (8 plates').
This
translates (1/1.166) to a minimum acceptable battery
capacity of 86 perceht for the battery to remaih
The 125 Vdc batte~y sizing calculation
- indicates a.total remaining margin of 47 percent~
This
translates (1/l.147) to a minimum acceptable battery
capacity of 68 percent.
The . inspector rev'.:i..ewed surveillance test procedure Nos~
DEP 8 3 00-2.0 (August 1989) , "2 50 Volt Station Battery
4
Performance Test," and DEP 8300-19*. (August 1989), "125
Volt Station Battery Performance Test" and determined
the procedures did contain adequate acceptance
criteria.
The 250 Vdc battery was to be declared
itioperable if its capacity was found to be less than 90
percent and the 125 Vdc battery inoperable if les*s than
80 percent.
Based on the above, this item is
considered closed.
e.
Deficiency 91-201-05:
Lack of 480 Vac Coordination
The EDSFI team determined that report No.
SL-4500~
dated March 24, 1989, did not demonstrate ~hat proper
electrical coordination existed between 480 Vac
components.
The following concerns were identified:
{l)
The report was not a controlled design document
and did not contain coordination curve.plots for
all devices.requiring coordination.
For example,
as-built_ plots were not provided for load breakers
at MCC Nos~ 29-3, 29-5, and 29~6.
.
.
(2)
Important information necessary to show adequate
coordination with equipment characteristics was
omitted.from the coordination curve pfots
including motor damage curves, maximum inrush
current; full lo.ad currents; locked rotor current
and cable thermal limits.
(3)
The maximum fault current shown on coordination
plots was 15,500A. * This value is bel6w the fault
currents determined in* calculation 6558-EAD-3 of
16,329A for bus No. 28 and. 16,0j8A for bus No. 29.
In addition, this value does not include motor
contributions from the 480V buses, which may
affect coordination for bus tie breakers and MCC
loa.d breakers.
(4)
Larik of coordination was noted between switchgear
Nos. 2~ and 29 feed break~rs and ~he bus tie
breakers.
(5)
Lack of coordination was noted between several MCC
feed and MCC load circuit breakers.
The EDSFI team noted that modifications were in
progress to resolve coordination problems.
The
licensee was replacing older electro-mecbani6al trip
current sensing devices with new solid state models
(RMS 9) .
.The replacement* schedule appeared to be based
on breaker preventive maintenance schedules that extend
into late 1995.
5
-
-~ ----.----------~-*---~~---~
The safety related buses at Dresden also supply power
to nonsafety lo.ads.
The NRC is also concerned that a
faulted, miscoordinated nonsafety 1oad eould cause the
loss of safety relat.ed equipment. * At the time of . this
inspection, the proposed modifications to improve
coordination had not been completed.
This item is
cpnsidered* an unresolved item (237/91038-04(DRS);
249/91042-04 (DRS)) pending NRC review of the lic.ensee' s
corrective actions.
f.
Unresolved Itein 91-201*-06:
Adequacy of Cable Ampacity
was not Established
The licensee was .unable to prov~de documentation to
establish that cables were properly sized.
The Sargent
and Lundy Interactive Cable Engineering (SLICE) program
was* run.to determine if currently *installed power*
cables*. were adequately sized to carry their. load
current.
Approximately 120 routing points were
identified as potentially thermally overloaded*.
Analysis of each routing point is currently ~n
progress.* In addition, the licensee committed to
perform a *pilot study to randomly verify the SLICE
routing information.
This is considered an unresolved
item (237/91038-0S(DRS): 249/91042-0S(DRS}) pending NRC
.review of the routing point*overload analysis and the*
pilot program re~u1ts .
. g.
Unresolved Item 91~201~01:
High Uhit 2/3 EDG Room
Temperature
The EDSFI team found the Unit 2/3 EOG room to be
excessively hot.
The diesel room was not provided with
any forced ventilation when in standby mode.
The Unit
2.and Unit 3 diesel rooms each r~ceive *1,000 cfm of air.
flow when in standby.
The electrical relays for the
EOG generator and exciter are rated for a maximum
temperature of 122°F.
The licensee committed to.
monitor the 2/3 EOG room temperature each shift.
If
the temperature exceeded 118.4°F, the operator was
instructed to start the vent fan for a period of time
to reduce the temperature below 114.B"F~
The licensee
plans to trend the 2/3 EOG.room temperatures during the
summer of 1992 and to assess the need for permanent
forced ventilation at that time *. This is considered an
open item (237/9103~-0G(DRS)) pending NRC review of the
licensee's assessment.
6
h.
Unresolved Item 91-201~08: Insufficient Fuel in EOG
Day Tanks
The EDSFI team was concerned that -insufficient fuel was
being maintained in the day tanks.to provide EOG
operation for four hours at rated load.
The FSAR fuel
consumption rate wa~ 192 gallons per hour.
Therefore,
768 gallons of fuel was required in the day tank.
The
fuel transfer pump automatic stop was set at 743
gallons (185.75 gallons per hour).
The licensee
provided the inspector fuel consumption tests that.were
performed prior to the EDSFI.
The following fuel
consumptions were determined:
- unit 2
- unit.3
- *units 2/3
_,
184.43 gallons per hour
171.67 gallons per hour
183.74 gallons per hour
In each case, sUffici~nt fuel was maintained in the
days tanks.
The licensee plans to evaluate EDG fuel oil day tarik
level instrumentation design changes as a long term
actibn tb assure four hours* of fuel will be
automatically.maintained in the day tanks:* In
addition, the "licensee coiilmitted_ to perfo:i;-m semiannual
£uel consumption ~est~ for all EDGs.
Based on the
above, this item is considered cl9sed.
i.
Deficiency 91-201-09:
Inadequate Post Modification
Testing
The EDSFI_ team determined that contact Tl/Ml of control
relay 2871/a had not been tested during post-
modification testing of Modification No. Ml2-2-88-05,
"Replace Feed Breakers on MCC 28/29-7." -Procedure OAP
5-1, "Plant Design Change Program," required-a_test be
performed to written instructions including acceptance
criteria that demonstrated the modified component
funcitioned properly and did not affect the
interrelationship with other components.
Special test-
procedU:re No.
SP-89-1~4, Revision o, "LPCI Swing Bus,"
did not include acceptance criteria that verified
contacit Tl/~l would trip breaker No. 2971.
In
addition, construction testing did not contain
-documented evidence that specific circuit checkout
- criteria had been met.
Failure of the licensee's post modification test
procedure to include appropriate acceptance criteria is
a violation (237/91038-07(0~8); 249/91042-07(0RS)) of
10 CFR 50, Appendix.B, Criterion v. _
7-
The licensee plans to retest the affected circuits
described above in accordance wi~h Dre~den's Safety
Related Contact Testing Adequacy Program.
3.
250 Volt Battery Testing
On October 14,
1991~ CECo removed the Dresden Unit 3 250 Vdc
battery from.service in preparation for a service test.
Prior to this date, the licensing basi~ for Dresden only
required a rated load discnarge*test (performance test) each
refueling outage to demonstrate battery operability.
The
service test was performed utilizing the original battery
sizing profile.
During .the first minute of the test, when
. subjected to a load of 1017 amperes, the battery voltage
decreased to 209.1 volts (acceptance/criteri~ was 210
v.ol ts) ...
On October 18, 1991, following a recharge of the .batter~, a
performance test was performed to determine whether the
service test failure was due to battery degradation.
The
test demonstrated that battery capacity was 96%.
This valtie
was within 10% of the previous.test which satisfied the
acceptance criteria specified in IEEE 450.
On October 20, 1991, the licensee developed a new worst case
load profile based on a large break LOCA an.d HPCI in
standby.
The NRC's review of this.profile questioned the
li~ensee's methodology for addressing the potential
coincidence of random.loads.
The NRC also questioned the
licensee's decision not to address the potential effects of
~HPCI being in test~
The prbfile indicated the main turbine
emergency bearing oil pump (EBOP) would start at 57 seconds
into the event.and a cycling of the HPCI valves due to
reactor high water level could occur at 62 seconds into the
event.
Since plant.operators had been trained to manually
start the *EBOP pump on a turbine trip ~nd since the cycling
of theHPCI valves, depending on break size, could occur
simultaneously with th~ start of the EBOP pufup, these loads
were considered to be random~
The controlling profile
segme_nt was the one to two minute period.
Adding the
purrent resulting from the cycling HPCI valves and the EBOP
- pump starting current would cause t.he profile peak to be.
.
greater than 1200 amperes, which exceeds the battery sizing
cal6ulation first minute current (1017 ~mperes).
The licensee develop*ed another .load profile which had a
first ~inute peak current of 910 ~mperes. This profile was
based on a large break LOCA'with HPCI in test.
To meet this
profile, the licensee modified the HPCI system adding
interposing relays in the HPCI valve circuits to prevent
coincident operation of the HPCI valves.
In addition, plant
procedures were modified to delete the instructions to plant
8
operators to manually start the EBOP pump.
On November l,*
1991, a service test was performed utilizing the revised
load profile.
The battery m_aintained a voltage of 211. 76
volts during the first minute and maintained a voltage of
greater* than 210 volts fo~ the remainder of the four hour
test.
Subsequently, the licensee identified a small.break
LOCA profile with HPCI in. standby that had the potential to
produce a 953 ampere current peak 6 minutes into the *
profile.
This peak exceeds th.e large break LOCA first
minute current of 910* amperes.*
The licensee *considered *this
momentary current peak to be of such short duration (60
milliseconds or less) that equipment would not be adversely
affected.
In addition, the licensee also considered the
pro:file to be conservativ~, based on momentary loads having
to be considered for a full minute in the tes.t profile.
In addition to the HPCI modifications and the plant
procedure modifications described above,*the licensee's
corrective actions include increasing the existing battery
size from116 cells to 120 cells, and a commitment to
install a new nonsafety related 250 Vdc battery to supply
the EBOP pump.
The licensee reported this item in LER No.91-013.
This LER will remai_n open (249/91013-LL) pending
NRC review of the licensee's corrective actions.
4 .
- Open Items
Open items are matters which have been discussed with the
licensee, which will be reviewed further by the NRC, and
which involve some action on the part of the NRC or licensee
6r both.
Open items discussed during this inspection are
discusse~ in Paragraphs 2.b., 2.g., *and 3.
5.
Unresolved Items
- Unresolved items are matters about which more information is
required.in order to ascertain whether they are acceptable.
items, violations, or deviations.
Unresolved *items
disclosed_during this*inspection are discussed in Paragraphs
2 . b . ; 2 . c . *, . 2 * e ~ , and 2 . f.
6.
Exit Interview
The inspectdr met with licensee representatives (denoted in
Paragraph 1) following the inspection on December 6, 1991,
to discuss the scope and findings of the inspection.
The
- . inspector** also discussed the likely. informat:ional content of
the inspection report with regard to documents or processes *
reviewed-by the inspector during the inspection.
Licensee
repre~entatives did not id~ntify any sueh documents or
processes as proprietary.
9
. --
-~ -..--~-~--- ------ _______ __... ____ -.-*.
- ~:
- APPENDIX A
Concern Number
Title
Status
a. Deficiency 91-201..:.01
Inadequate Short
237/91038-01
Circtiit Capability
249/91042-01
of 4kV Circuit Breakers .*
b. Deficiency 91-201-02
Inadequate Calculation
237/91038-02
to Determine Degraded
- 249/91042-02
Grid Relay Trip Setpoint
-c~ peficiency 91-201-03 ..
Failure to.Take
237/91038-03
- .Prompt Correctfve Action 249/91042-03
d. Deficiency 91-201-04
e. Deficiency.91-201-05
f. Unresolved Item
91-201-06
g. Unresolved Item
.
.
91-201-07
ll * Unresolved Item
91-201-08"
i. Deficiency 91.,..201-09
Licensee Event Report
a. 91.,..013-0
b. 91-021-0
---* -~----------~- -~--~----.- --
Inadequate Acceptance**
Criteria for Battery
Surve~llances
Lack of 480 Volt
Coordination
Adequacy of Cable
Ampacity was not
Es.tablished *
High Unit 2/3 EDG
Room Temperature
Insufficient Fuel in
EDG Tanks
Inadequate Post*
Modification-Testing
Closed
237/91038-04
249/91042~04
237/91038-05-
249/91042-05
237/91038-06
- closed
237/91038-07
249/91042-07
Title
Status
250 Volt DC Battery
249/91013-LL
Discharge Voltage
Decreased Below Design .
Basis Limit*
Imprope~ Setpoint of
237/91021-LL
Second Level Undervoltage
Relays Due to Management
Deficiency