ML20247D241
| ML20247D241 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 05/15/1989 |
| From: | Ebneter S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Tucker H DUKE POWER CO. |
| References | |
| NUDOCS 8905250279 | |
| Download: ML20247D241 (31) | |
See also: IR 05000369/1989005
Text
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MAY 151989
Docket Nos. 50-369, 50-370
Duke Power Company
ATTN: Mr. H. B. Tucker, Vice President
Nuclear Production Department
422 South Church Street
Charlotte, NC 28242
Gentlemen:
SUBJECT: ENFORCEMENT CONFERENCE SUMMARY
NRC INSPECTION REPCRT NOS. 50-369/89-05 AND 50-370/89-05
This letter refers to the Enforcement Conference held at our request on
April 28, 1989. This meeting concerned activities authorized for your McGuire
facility.
The issues discussed at this conference related to the Instrument Air (VI)
system interface with the Diesel Generator Starting Air (VG) system.
A' list of attendees, a summary, and a copy of your handout are enclosed. We
are continuing our review of these issues to determine the appropriate
enforcement action.
In accordance with Section 2.790 of the NRC's " Rules of Practice," Part 2,
Title 10, Code of Federal Regulations, a copy of this letter and its enclosures
will be placed in the NRC Public Document Room.
Shou?d you have any questions concerning this letter, please contact us.
Sincerely,
/W
Stewart D. Ebneter
Regional Administrator l
Enclosures:
1. List of Attendees ;
2. Enforcement Conference Summary
3. Handout
cc w/encls:
T. L. McConnell, Station Manager
Senior Resident Inspector - Catawba
State of North Carolina
bcc w/encls: (See page 2)
8905250279 890515 I I
PDR ADOCK 05000369
Q PDC
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ENCLOSURE 1
LIST OF ATTENDEES
U.S. Nuclear Regulatory Commission
S. D. Ebneter, Regional Administrator
C. W. Hehl, Deputy Director, Division of Reactor Projects (DRP)
E. W. Merschoff, Deputy Director, Division of Reactor Safety (DRS)
G. R. Jenkins, Director, Enforcement and Investigations Coordination Staff
(EICS)
A. R. Herdt, Branch Chief, DRP
M. B. Shymlock, Section Chief, DRP
P. K. VanDoorn, Senior Resident Inspector, McGuire, DRP
Duke Power Company
H. B. Tucker, Vice President, Nuclear Production
T. L. McConnell, Station Manager, McGuire
D. W. Murdock, McGuire, Design Engineering Manager
R. L. Gill, Regulatory Compliance Manager
P. R. Herran, Design Engineer
R. O. Sharpe, McGuire Compliance
B. Travis, Superintendent of Operations
J. T. Fuller, McGuire Operations
J. S. Warren, Regulatory Compiionce
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1.
ENCLOSURE 2
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ENFORCEMENT CONFERENCE SUMMARY
On April 28, 1989, representatives from Duke Power Company (DPC) met with the
NRC in the Region II office in Atlanta, Georgia to discuss (.oncerns regarding
the Instrument Air (VI) system interface with the Diesel Generator Starting Air
(VG) system.
Following opening remarks by S. Ebneter, NRC RII Regional Administrator, DPC
gave a presentation (Enclosure 3) on the subject identified above. The DPC
presentation covered a system description, sequence of events, safety
significance, root cuse, corrective actions, and operations response to the i
event. T. McConne*,6, Station Manager, McGuire summarized the presentation
followed by H. Tucker, Vice President, Nuclear Production, directing closing
remarks.
DPC stated that the deficiency was identified during a Self-Initiated Technical
Audit (SITA) of the VG system. The deficiency involved automatic alignment of
VG to VI and that a portion of VG was not clEssified as seismic. DPC discussed
corrective actions and an operability determination of the diesel. They also
concluded that their was no safety issue even durirg a LOCA with a seismic
event.
The NRC closed the meeting by stating that it had served to enhance Region II's
understanding of the issues and DPC's corrective actions.
I
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ENCLOSURE 3
ENFORCEMENT CONFERENCE
DUKE POWER COMPANY
MCGUIRE NUCLEAR STATION
,
DIESEL GENERATORSYSTEM STARTING (VI)
AIR SYSTEM (VG)/ INSTRUMENT
APRIL 28, 1999
NRC' REGION II 0FFICE - ATLANTA
- AGENDA * * *
H. B. TUCKER
1. OPENING REMARKS T. L. MCCONNELL
P. R. HERRAN
2. SYSTEM DESCRIPTION
R. O. SHARPE
3.
,
SEQUENCE OF EVENTS ,
P. R. HERRAN l
'
4. SAFETY SIGNIFICANCE / ROOT CAUSE/
CORRECTIVE ACTIONS
J. T. FULLER
5. OPERATIONS RESPONSE TO THE EVENT
T. L. MCCONNELL
6. SUMMARY STATEMENT
H. B. TUCKER
7. CLOSING REMARKS
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DIESEL STARTING AIR SYSTEM
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DESIGN BASES
0~ START EMERGENCY D/G AT LEAST TWICE, CONSECUTIVELY.
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EACH START LESS THAN OR EQUAL TO 11 SEC.
O SUPPLY CONTROL AIR TO DIESEL CONTROLS AND
INSTRUMENTATION " START" AND "RUN" CONDITION
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VI Blackout Header
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Note 1
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Blackout Air
Diesel Gen. A
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supply
Note 1. Opens on a L'oss of Offsite Power, remains closed
on LOCA.
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BLACK 0UT CONTROL AIR HEADER q
" DESIGN BASES .
8 NOT SAFETY RELATED
8 MCGUIRE IS " HOT STANDBY" PLANT
0 LOSS OF 0FFSITE POWER WITH & WITHOUT CONTROL
ROOM EVACUATION
0 OPERATING PROCEDURES SUPPORT OPERATOR ACTION
REQUIREMENTS
8 REVISE FSAR SECTION 9.3.1.3 TO CLARIFY HOT
STANDBY AND COLD SHUTDOWN BASIS
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specification 288.1, Type I, Class 0 air quality. After the filters, air from
both compressors dircharge into a common receiv'ar tank. .
_
'
From the'd tank,' breathind air is suppl.ed to various locations in he
Auxiliary; .and'inside the Containment. Isolation valves locsted
outsids ther neont are installed in series with check valves located
inside the Containment for each breathing air containment penetration.
'In addition to the screw compressors, two low pressure Itquid ring compressors
can be used as backup. Each of these compressors discharges to a water
separator and then to a receive tank.
9.3.1.3 Safety Evaluation
The compressed air systems are designed to provide a dependable source of
compressed and' cooled air for station serv.f ce, breathing testing, and instrum
sentation requirements. Sufficient redundancy is provided to give e M $ -
degree of reliability of air supply at all times. Sufficient air resolver .ne.
capacity is provided to meet system high ir demand transient 4 ,,.. %.]
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Los.s J W jhu- (s_ cop') .
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A foss of instrument air due to a "Stacheut" during norms) operetten causes th. . *
.
pneuestically operated valves in the station which are essential fem safe ,
shutdown to fail to the safe position. However, many of these valves requitte
an air supply in the evint of Control Room evacuation coincident wgi
normal electrical poweMD If this accident occurs, the plant can L2...tetw-J )gss of'
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""O i : M ;" condition from the auxiliary shutdown panel and the auxiliar
l
the
ry b ter panel. Therefore, air headers have been provided in the Auxiliary o
Building and both ContainmentQgpply air to only those valves which are -
u .c. 2 2. The valves which pegweee a blackout air supply are listed in Table
9.3.1-3. These headers are protected against depressurization by check valves
IV1122, IV1153, 2V1122 and 2V1153. Air storage for these headers are provided
by the Instr nt Compressed Air Tanks. Since the diesel generator power
during " " is not available for the Instrument Air Compressors, the
blackout air supply headers are aligned to the Diesel Gaperator Starting Air
System headers through a normally closed solenoid valv & Thoth solenoid valves
must receive a "S4eehowt" and a " Diesel Running" signa 13to open.
'OP w a. LOCA s;gncd
An ASME,Section III, Class 3 air reservoir is provided o/o n the instrument air
piping to each main steam isolation valve operator. Redundant ASIE, Section
III, Class 3 check valves are provided upstreas of each air reservoir for
isolation free the remainder of the Instrument Air System. The interconnecting
piping between the check valves, air reservoirs and the main steam isolation
valve operators is Duke Class C. (Refer to Figure 9.3.1-2). These safety
class air reserveles are provided as a redundant means of closure for each asin
steam isolation valve. These valves are aise capable of being closed by spring
action. Each reservoir has air capacity for a single closure of its respective
main steam isolation valve. Air reservoir design
.
.
A
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Past Operability of VG/VI ,
fwo Problems Identified: l
designed
-1
- Seismic - VI was not originally
as a. seismic system
Consumption by Blackout Header ,
2 -
Air
a-Information not generally available
from vendors
air consumption
would
b- Actual header
of valves
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depend on operator cycling
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Operability Considerations
1 - Seismic - Due to small pipe size low mass, and adequate
support, it was felt that the blackout header
could be shown to be seismicly rugged
.
2 - Air Consumption
a -Preoperational testing had not identified any problems
b -Previous short duration blackout had not indicated a
problem with VG/VI ,
Conclusions
1) VG/VI interface capable of performing its design function.
from a seismic standpoint
2) Past operability could not be determined without testing
.
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. 8
VG/VI Test Considerations
1.- Blackout header cannot be tested
with the Unit above mode 5 .due to
the impact on valves
2- Even with a unit in No-Mode
(defueled) there are safety
concerns with the potential impact
i on the other unit because of the
,
shared VI System
3- Test method (static test, dynamic
test, number 'of compressors, etc)
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Unit 2 VG/VI Tests
6/28/88 2B VG to VI Blackout Header Test
Test Method-2B VG compressors and receivers were
aligned to 2B blackout header
Results-Little or no change in VG or VI pressure
(most loads were isolated from the header)
7/20/88 2A VG to VI Blackout Header Test
Test Method-Same as 2B except that all loads were
verified to be aligned to the header
Results-Pressure in VI dropped to test termination
'
point (approx. 80 psi); VG unaffected
Conclusion at end of Unit 2 RFO
1) Regulator protected the VG system
2) Seistnic analysis of blackout header unnecessary ;
3) Not reportable
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Unit 1 VG/VI Testing
11/11/88 1A VG to VI Blackout Header Test
.
Test Method-Same as 2 A except that a 30 cfm load
was induced
Results- 1) VG compressor w cs able to maintain VG
pressure
f 2) Check valve 1 VI- 12 2 did not seat
Conclusion:
11/15/89 Due to leaking
1 -Test results were evaluated on
check valve, test failed
2-With past condition of the check valve indeterminate,
past operability of D/G 1 A could not be assured. Event
was reported on 11./15/89
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Additional Testing
January 1989
1- Focused attention on the filter regulator
If this valve passed less air than the compressor could
supply - would be no impact on VG if VI broke in a
seismic event
2- By field testing and bench testing it was determined that:
a- D/G run/ shutdown cylinder needed 55 psig to remain
open
b- The filter regulator valve could pass greater than the
compressor capacity at 20 psig
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VG/VI
Conclusions
After identifying problem we moved quickly to:
1-
a- Assure current operability
b- Determine past operability
2- Develope a test program to determine operability
refine method and test additional
3- Continued to test
trains until we found an inoperable train
4- Kept Resident Inspectors informed
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4-
SAFETY SIGNIFICANCE OF ORIGINAL CONFIGlJRATION
.
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EVENT LOOP W/LOCA
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I NO SAFETY ISStJE
8 VG S0LEN0ID VALVES REMAIN CLOSED FOR LOCA
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6
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SAF~.TY SIGNIFICANCE OF ORIGINAL CONFIGURAT
EVENT - LOOP W/0 SEISMIC
DIESELS
8 NON-SAFETY INSTRUMENT AIR RtMAINS
8 DIESELS SUPPLY Alit TO SEPARATE BLACK 0UT
HEADERS WHICH ARE SEPARATED BY CHECK V
8 NORMAL & BLACK 0UT HEADERS INSTRUMEN
AVAILABLE
.
8 LIMITED AIR USEAGE SIMULATION OF THE
AIR HEADER HAVE BEEN INCONCLUSIVE
DIESEL ALTERNATIVES
8 STANDBY SHUTDOWN FACILITY IS CAPABLE
TAINING HOT STANDBY CONDITIONS
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a.
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SAFETY SIGNIFICANCE OF P11GINAL CONFIGURATION
EVENT - LOOP W/ SEISMIC
DIESELS
8 BLACK 0UT AIR HEADER
SEISMICALLY RUGGED (SQuG)
N0 UNACCEPTABLE INTERACTIONS
0 DIESEL STARTING AIR COMPRESSORS, AFTERC00LERS, DRYERS
AND PIPING
COMPRESSORS SEISMICALLY QUALIFIED
OTHER COMPONENTS SEISMICALLY RUGGED (SQUG) ,
NO UNACCEPTABLE INTERACTIONS
8 THEREFORE, CONCLUSIONS STATED FOR LOOP W/0 SEISMIC ALSO
APPLY
'
DIESEL ALTERNATIVES
,
8 TURBINE DRIVEN AUXILIARY FEEDWATER PUMP IS SEISMICALL
'
QUALIFIED
e THE SSF IS NOT SEISMICALLY QUALIFIED.BASED ON A SEISMIC
REVIEW, THE SSF WOULD BE EXPECTED TO REMAIN FUNCTIONAL
FOLLOWING AN SSE.
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ROOT CAUSE
.
8 AT THE TIME THE VG/VI INTERFACE WAS DESIGNED, THERE WAS
INSUFFICIENT DESIGN BASIS DOCUMENTATION THAT THE DIESEL
GENERATOR CONTROLS REQUIRED CONTINUED AIR PRESSURE TO BE
MAINTAINED AFTER THE ENGINE !!AD STARTED IN ORDER FOR THE
ENGINE TO CONTINUE TO OPERATE
,
e
W
G
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LONG TERM CORRECTIVE ACTIONS
SPECIFIC CORRECTIVE ACTIONS
8 SEISMICALLY QUALIFY DIESEL GENERATOR ENGINE
STARTING AIR AFTERC00LERS, DRYERS AND PIPING
8 UPDATE FSAR TO CLARIFY HOT STANDBY VERSUS COLD
SHUTDOWN BLACK 0UT AIR HEADER BASIS
8 PURSUE ALTERNATE SOURCE OF AIR FOR THE BLAC
GENERIC CORRECTIVE ACTIONS
0 TOPFORM (DESIGN INPUTS, SITA, IDRs, ETC.)
e DESIGN BASIS DOCUMENTATION
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e
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Operations' Response to the Event
to
- Implemented CONSER VA TIVE measures
FUTU2?E operability
ensure PRESENT and
.of the Diesel
Generators, regardless of test
results
ACTION
Shut manual VG-VI isolation
valv . , .
,
-
-
Procedure changes: -
-Loss of Instrument Air
(Abnormal Procedure 22)
-Loss of Control Room
(Abnormal Procedure 17)
- Training / Required Reading
involvement in test development
- Continuing
.
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Pre-Isolation Review
-
The effect would have been
dependent on fault location
and operator action.
- Mitigating factors:
-
On Diesel start, Operator
automatically inspects D/G
-
Control Room trouble
-
2 annunciator alarms
-
System reserve and tank
blowdown time .
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Post-Isolation Review
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VG allowed to supply VI
Ble.ckout Header only under
carefully controlled
1
conditions.
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DIESEL GENERATOR STARTING AIR (VG)/ INSTRUMENT AIR (VI) INTERFACE
NRC ENFORCEMENT CONFERENCE
APRll 28, 1989
SUMMARY STATEMENTS
(1) McGUIRE EXPEDITIOUSLY INVESTIGATED THE WHEN VG/Vi INTERFACE
RESULTS
PROBLEM RAISED BY THE SITA IN MAY, 1988.
INDICATED THE POSSIBILITY OF INOPERABILITY UNDER CERTAIN
CONDITIONS, IMMEDIATE. ACTIONS WERE TAKEN TO ISOLATE VG FROM
THIS WAS
VI AND ASSURE OPERABILITY OF THE D/G'S.
CONSERVATIVE AND IMMEDIATE ACTION TO ASSURE CURRENT AND
FUTURE OPERABILITY.
(2) IN MAY 1988 WE BELIEVED THAT PAST OPERABILITY COULD BE
PROVEN FROM A SEISMIC AND AIR CONSUMPTION STANDPOINT;
THEREFORE, WE DID NOT REPORT THE EVENT. WITH CURRENT
OPERABILITY ASSURED, WE THEN DECIDED TO SYSTEMATICALLY TEST
AND EVALUATE THE VG/VI INTERFACE TO PROVE PAST OPERABILITY.
(3) TESTING ON UNIT 2 IN JUNE AND JULY 1988 SUPPORTED PAST
OPERABILITY AND WE COULD HAVE STOPPED THE INVESTIGATION A
THAT POINT. HOWEVER, FURTHER REVIEW OF THE TEST INDICATED
IT WAS INCONCLUSIVE AND WE PROCEEDED WITH PLANS TO TEST
1 DURING UPCOMING REFUELING.
(4) WHEN THE EVALUATION OF THE TESTING ON UNIT 1 INCAUSED NOVEMBER
1968 REVEALED THAT THE FAILURE OF VI-122 CHECK VALVE
THE PAST INOPERABILITY OF D/G 1A WE EXPEDITIOUSLY REPORTED
IT TO THE NRC.
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ee se p
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(5) THE REASON THE PAST OPERABILITY EVALUATION TOOK SO LONG WAS
DUE TO THE FACT THAT TESTING COULD ONLY BE DONE UNDER
CERTAIN CONDITIONS DURING REFUELING OUTAGES AND THEN IT WAS
WITH A CERTAIN DEGREE OF RISK.
(6) BECAUSE OF ALL THE UNCERTAINTIES IN DETERMINING THE ACTUAL
AIR LOADS ON THE BLACK-OUT AIR HEADER, ANY TESTING WE COULD
POSTULATE WOULD NOT PROVIDE ABSOLUTE ASSURANCE OF PAST
OPERABILITY. THEREFORE, DUE TO THE SAFETY RISK ASSOCIATED
WITH A COMPREHENSIVE TEST AND THE LIMITED BENEFITS TO BE
GAINED, WE DECIDED TO TERMINATE ANY ADDITIONAL TESTING THAT
PLACED A TRANSIENT ON THE B. O. HEADER. CURRENT OR FUTURE
PLANT SAFETY WOULD NOT BE ENHANCED BY FURTHER TESTING.
(7) BECAUSE WE COULDN'T PROVE OPERABILITY ON THE OTHER 3 TRAINS
(2A, 2B, AND 18) WITH SOLID EVIDENCE WE DECIDED TO REPORT
THE D/G'S INOPERABLE UNDER CERTAIN CONDITIONS FROM STARTUP
TO MAY 20, 1988. THE LER WAS SUBMITTED IN DECEMBER 1988.
(8) THE POSSIBILITY Dl0 EXIST THAT THE OTHER 3 TRAINS OF D/G'S
COULD HAVE BEEN OPERABLE IF THE FILTER REGULATOR VALVES
BETWEEN VG AND VI WOULD ACT AS AN ORIFICE TO PREVENT BLEED
DOWN OF THE VG SYSTEM. THIS WAS TESTED IN JANUARY 1989 AND
FAILED.
(9) IT IS STILL INCONCLUSIVE AS TO WHETHER OR NOT THE OTHER
THREE TRAINS OF VG WERE INOPERABLE IN THE PAST, BECAUSE WE
HAVE DETERMINED THAT THE PIPING WOULD WITHSTAND A SEISMIC
EVENT AND ACTUAL AIR LOADS MAY BE WITHIN THE CAPABILITY OF
THE VG COMPRESSORS.
(10) WE FEEL THAT OUR ACTIONS WERE CLEARLY PRUDENT, BASED ON WHAT
PLANT SAFETY WAS A
WE KNEW AT THE 11ME OF OUR DECISIONS.
TOP PRIORITY THROUGHOUT THE EVALUATION PERIOD AND WAS
EVIDENT IN THE DECISIONS MADE.
.
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