Information Notice 1993-51, Repetitive Overspeed Tripping of Turbine-Driven Auxiliary Feedwater Pumps: Difference between revisions
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| issue date = 07/09/1993 | | issue date = 07/09/1993 | ||
| title = Repetitive Overspeed Tripping of Turbine-Driven Auxiliary Feedwater Pumps | | title = Repetitive Overspeed Tripping of Turbine-Driven Auxiliary Feedwater Pumps | ||
| author name = Grimes B | | author name = Grimes B | ||
| author affiliation = NRC/NRR | | author affiliation = NRC/NRR | ||
| addressee name = | | addressee name = | ||
Line 14: | Line 14: | ||
| page count = 12 | | page count = 12 | ||
}} | }} | ||
{{#Wiki_filter:r -UNITED STATES | {{#Wiki_filter:r - | ||
UNITED STATES | |||
COMMISSION | NUCLEAR REGULATORY COMMISSION | ||
OFFICE OF NUCLEAR REACTOR REGULATION | |||
NOTICE 93-51: REPETITIVE | WASHINGTON, D.C. 20555 July 9, 1993 NRC INFORMATION NOTICE 93-51: REPETITIVE OVERSPEED TRIPPING OF TURBINE-DRIVEN | ||
AUXILIARY FEEDWATER PUMPS | |||
==Addressees== | |||
nuclear power | |||
All holders of operating licenses or construction permits for | |||
reactors. | |||
==Purpose== | |||
information | |||
The U.S. Nuclear Regulatory Commission (NRC) is issuing this of turbine- notice to alert addressees to the problem of repetitive tripping | |||
Project Electric | |||
driven auxiliary feedwater pumps (TDAFWPs) at the South Texas the | |||
Generating Station. It is expected that recipients will review | |||
actions, as | |||
information for applicability to their facilities and consider contained in | |||
appropriate, to avoid similar problems. However, suggestions no specific | |||
this information notice are not NRC requirements; therefore, action or written response is required. | |||
==Description of Circumstances== | |||
On December 27, 1992, Houston Lighting & Power Company (the licensee) receiving a | |||
performed a monthly surveillance test on its Unit 1 TDAFWP. After The | |||
start signal, the pump immediately tripped on an overspeed condition. | |||
local manual | |||
operators repeated the surveillance test after a successful the licensee | |||
start. On this attempt the pump successfully started, and | |||
subsequently considered the pump operable. | |||
water level | |||
On January 23, 1993, Unit 2 tripped from 100-percent power on low | |||
in one of the steam generators. The trip occurred because electro-hydraulic | |||
was lost. The | |||
control oil to the steam generator main feedwater pump turbine longer required. | |||
secured when no | |||
Unit 2 TDAFWP started on demand and was later attempted to | |||
After the pump was secured, problems occurred when operators | |||
from the control room. (See | |||
a | relatch MOV-514 (the TDAFWP trip/throttle valve) a | ||
The licensee conducted | |||
Figure 1.) The pump was declared inoperable. to resolve the | |||
significant amount of troubleshooting and testing on the TDAFWP was identified | |||
MOV-514 relatch problem and another speed control problem that | |||
was completed | |||
during the testing. After the operability surveillance test was restarted on | |||
successfully, the TDAFWP was declared operable and the unit | |||
January 25, 1993. | |||
a routine monthly | |||
On January 28, 1993, the Unit 1 TDAFWP was tested as part of | |||
immediately tripped on an overspeed | |||
surveillance. When started, the TDAFWP 28 through | |||
condition and was subsequently declared inoperable. From January | |||
9307010233 P PC w3 9t - oSI 915 I | |||
-I | |||
IN 93-51 July 9, 1993 and | |||
January 30, 1993, the licensee undertook an extensive testing with the TDAFWP. | |||
troubleshooting effort to determine the cause of the problem | |||
Several problems (overspeed tripping, Numerous pump starts were completed. full- and inability to maintain rated | |||
lack of speed control, oscillations, the Unit 1 load, steady-state speed) were identified. On January 30, 1993, and | |||
TDAFWP was declared operable following extensive maintenance activities | |||
the successful completion of the surveillance test. | |||
direction of | |||
On February 1, 1993, the Unit 1 TDAFWP was tested again at the considering the | |||
the Unit 1 operations manager in order to ensure operability, signal, the | |||
numerous problems encountered previously. After receiving a start | |||
tripped on an overspeed condition | pump tripped on an overspeed condition and was declared inoperable. | ||
Two steam- On February 3, 1993, Unit 2 was operating at 100-percent power. feedwater | |||
driven steam generator main feedwater pumps and one electric startup | |||
feedwater | |||
pump were providing feed flow to the steam generators. The startup being | |||
pump tripped when the pump lubricating oil duplex strainers were to avoid | |||
shifted. Operators began to manually ramp down power but were unable | |||
initiated a manual | |||
the | the low steam generator level. The operators subsequently system trip | ||
reactor trip before receiving an automatic reactor protection Unit 2 signal on low steam generator level. Following the plant trip, the | |||
the steam generators. | |||
to | TDAFWP received an automatic signal to supply water to | ||
The pump started but immediately tripped on an overspeed condition. | |||
in the | |||
On February 4, 1993, Unit 1 commenced a shutdown to place the reactor had not been | |||
mode required by the Technical Specifications because the TDAFWP | |||
allowed by the | |||
restored to an operable condition within the outage time | |||
Technical Specifications. | |||
NRC | |||
Further details can be found in License Event Report 50-498/93-007 and | |||
Inspection Reports 50-498; 50-499/93-05 and 50-498; 50-499/93-07. | |||
Discussion | |||
the | Although the licensee did not identify the root cause of the Unit 1 TDAFWP of | ||
overspeed trips, the proximate cause was determined to be the intrusion | |||
water into the TDAFWP turbine that adversely affected its performance. | |||
tests | |||
However, this cause was effectively masked for several surveillance | |||
because the surveillance test program established to satisfy the operability | |||
to | |||
requirements of the Technical Specifications was not sufficiently rigorous conditions. | |||
assure that the testing was performed under suitable environmental | |||
of the | |||
The TDAFWP was not returned to its normal standby condition before each | |||
TDAFWP surveillance tests performed on December 27, 1992, and | |||
normal | |||
January 30, 1993. Because of this, the pump was not tested in its not | |||
were | standby condition and degraded conditions affecting operability were | ||
revealed. | |||
IN 93-51 July 9, 1993 Unit 2 The licensee determined that the root cause of the February 3, 1993,with an | |||
TDAFWP overspeed trip was an incorrect valve lineup in conjunction | |||
located | |||
Inoperable or degraded steam trap. The valves and the steam trap are TDAFWP | |||
admission line. (See Figure 1.) The | |||
in the drain line from the steam supply | |||
overspeed trip was caused by excessive condensate buildup in the steam | |||
(MOV-514 in Figure 1). The excessive | |||
the | line upstream of the trip/throttle valve was | ||
condensate had accumulated because the steam trap bypass valve, MS-517, an | |||
the steam trap had degraded to such | |||
incorrectly positioned (closed) and condenser. | |||
extent that it was no longer capable of passing condensate to the | |||
The licensee took the following corrective actions related to the hardware | |||
modifications for both units: | |||
* The trip/throttle valves and governors were sent to the respective | |||
vendors for complete refurbishment and testing. The gearing arrangement | |||
of the trip/throttle valve was modified to ensure slower stroke time, thus enabling a more positive governor response. | |||
* The TDAFWP drain system was modified to remove the steam traps in the | |||
steamline drain system, replacing them with a spool piece. Also, the | |||
trip/throttle valve high-pressure steam leakoff was separated from the | |||
turbine casing drain line and rerouted to the sump to prevent possible | |||
intrusion of steam into the turbine casing. (See Figure 2.) | |||
Related Generic Communications | |||
* NRC Information Notice 86-14, Supplement 2, "Overspeed Trips of AFW, | |||
HPCI, and RCIC Turbines," dated August 26, 1991. | |||
* NRC Information Notice 88-09, "Reduced Reliability of Steam-Driven | |||
Auxiliary Feedwater Pumps Caused by Instability of Woodward PG-PL Type | |||
Governors," dated March 18, 1988. | |||
of | HPCI, | ||
* IE Information Notice 86-14, Supplement 1, "Overspeed Trips of AFW, | |||
and RCIC Turbines," dated December 17, 1986. | |||
* IE Information Notice 86-14, "PWR Auxiliary Feedwater Pump Turbine | |||
Control Problems," dated March 10, 1986. | |||
.IN | |||
* 93-51 July 9, 1993 If | |||
This information notice requires no specific action or written response. | |||
you have any questions about the information in this notice, please contact | |||
one of the technical contacts listed below or the appropriate Office of | |||
Nuclear Reactor Regulation (NRR) project manager. | |||
Brian K. Grimes, Director | |||
Division of Operating Reactor Support | |||
Office of Nuclear Reactor Regulation | |||
Technical contacts: Mark A. Satorius, RIV | |||
(817) 860-8141 William D. Johnson, RIV | |||
(817) 860-8148 Peter C. Wen, NRR | |||
(301) 504-2832 Attachments: | |||
1. Figure 1, Existing South Texas Project | |||
TDAFWP Steam Supply and Exhaust System | |||
2. Figure 2, Modified South Texas Project | |||
and | TDAFWP Steam Supply and Exhaust System | ||
3. List of Recently Issued NRC Information Notices | |||
MOV-143 STEAM EXHAUST | |||
LINE | |||
===STEAM ADMISSION=== | |||
LINE | |||
MOV-514 TERRY | |||
TURBINE ( | |||
STEAM ADMISSION PIPE CAP WITH ORIFICE | |||
LINE DRAIN If (UNIT I ONLY) | |||
VALVES | |||
MS | |||
371 MS | |||
370 MS TURBINE CASING | |||
FO 7537B 373 DRAIN VALVE | |||
~1 II | |||
STEAM TRAP STEAM FO 7537A-- | |||
BYPASS | |||
VALVE | |||
TRAP | |||
Yl (D% %Dn | |||
w I1 | |||
°% I'- | |||
CONDENSER I-a%0 w r | |||
0D | |||
FIGURE 1 TDAFWP STEAM SUPPLY AND EXHAUST SYSTEM (UNMODIFIED) | |||
MOV-143 STEAM EXHAUST | |||
LINE | |||
===STEAM ADMISSION=== | |||
LINE | |||
MOV-514 TERRY | |||
TURBINE C | |||
STEAM ADMISSION | |||
UNE DRAIN | |||
VALVES | |||
MS | |||
370 MS TURBINE CASING | |||
FO 7537B 373 DRAIN VALVE | |||
MS | |||
515 STEAM TRAP SPOOL | |||
BYPASS PIECE m'z ~ -- | |||
VALVE | |||
MS " MD3%Dt | |||
HAQ | |||
516 %O D | |||
CONDENSER " D | |||
Wa " | |||
FIGURE 2 TDAFWP STEAM SUPPLY AND EXHAUST SYSTEM (MODIFED) | |||
Attachment 3 IN 93-51 July 9, 1993 LIST OF RECENTLY ISSUED | |||
NRC INFORMATION NOTICES | |||
Information Date of | |||
Notice No. Subject Issuance Issued to | |||
93-50 Extended Storage of 07/08/93 All licensees authorized | |||
Sealed Sources to possess sealed sources. | |||
93-49 Improper Integration of 07/08/93 All holders of OLs or CPs | |||
Software into Operating for nuclear power reactors. | |||
Practices | |||
93-48 Failure of Turbine- 7/6/93 All holders of OLs or CPs | |||
Feedwater | Driven Main Feedwater for nuclear power reactors. | ||
Pump | Pump to Trip Because of | ||
Contaminated Oil | |||
92-06, Reliability of ATWS 07/01/93 All holders of OLs or CPs | |||
Supp. 1 Mitigation Systems and for nuclear power reactors. | |||
Other NRC-Required Equip- ment not Controlled by | |||
Plant Technical Specifica- tion | |||
93-47 Unrecognized Loss of 06/18/93 All holders of OLs or CPs | |||
Control Room Annunciators for nuclear power reactors. | |||
93-46 Potential Problem with 6/10/93 All holders of OLs or CPs | |||
Westinghouse Rod Control for Westinghouse (W)- | |||
System and Inadvertent designed nuclear power | |||
Withdrawal of A Single reactors. | |||
Rod Control Cluster Assembly | |||
93-45 Degradation of Shutdown 06/16/93 All holders of OLs or CPs | |||
Cooling System Performance for nuclear power reactors. | |||
93-44 Operational Challenges 06/15/93 All holders of OLs or CPs | |||
During A Dual-Unit for nuclear power reactors. | |||
Transient | |||
of | 93-43 Use of Inappropriate 06/10/93 All holders of OLs or CPs | ||
Lubrication Oils in for nuclear power reactors. | |||
Safety-Related Applications | |||
OL = Operating License | |||
CP - Construction Permit | |||
\,- | |||
IN 93-51 July 9, 1993 This information notice requires no specific action or written response. If | |||
you have any questions about the information in this notice, please contact | |||
one of the technical contacts listed below or the appropriate Office of | |||
Nuclear Reactor Regulation (NRR) project manager. | |||
orig /s/'d by BKGrimes | |||
Brian K. Grimes, Director | |||
Division of Operating Reactor Support | |||
Office of Nuclear Reactor Regulation | |||
Technical contacts: Mark A. Satorius, RIV | |||
(817) 860-8141 William D. Johnson, RIV | |||
(817) 860-8148 Peter C. Wen, NRR | |||
(301) 504-2832 Attachments: | |||
1. Figure 1, Existing South Texas Project TDAFWP | |||
Steam Supply and Exhaust System | |||
2. Figure 2, Modified South Texas Project | |||
TDAFWP Steam Supply and Exhaust System | |||
3. List of Recently Issued NRC Information Notices | |||
*SEE PREVIOUS CONCURRENCE | |||
OFFICE *OGCB:DORS *DRP:RIV *TECH ED. *SC:DRP:RIV *D:DRP:RIV | |||
NAME PCWen/vsb l MASatorius MFMejac WDJohnson ABBeach | |||
DATE 06/01/93 l 06/02/93 06/02/93 06/04/93 06/04/93 | |||
*PM:PDV:NRR *C:SPLB:DSSA:NRR *D:DSSA:NRR *C:OGCB:DORS:NRR D | |||
LEKokaJko CEMcCracken ACThadani GHMarcus dd____ | |||
06/08/93 06/09/93 06/10/93 06/16/93 DOCUMENT NAME: 93-51.IN | |||
IN 93-xx | |||
June xx, 1993 This information notice requires no specific action or written response. If | |||
you have any questions about the information in this notice, please contact | |||
one of the technical contacts listed below or the appropriate Office of | |||
Nuclear Reactor Regulation (NRR) project manager. | |||
Brian K. Grimes, Director | |||
Division of Operating Reactor Support | |||
Office of Nuclear Reactor Regulation | |||
Technical contacts: Mark A. Satorius, RIV | |||
(817) 860-8141 William D. Johnson, RIV | |||
(817) 860-8148 Peter C. Wen, NRR | |||
(301) 504-2832 Attachments: | |||
1. Figure 1, Existing South Texas Project TDAFWP Steam Supply and Exhaust | |||
System | |||
2. Figure 2, Modified South Texas Project TDAFWP Steam Supply and Exhaust | |||
System | |||
3. List of Recently Issued NRC Information Notices | |||
*SEE PREVIOUS CONCURRENCE | |||
OFFICE *OGCB:DORS *DRP:RIV *TECH ED. *SC:DRP:RIV *D:DRP:RIV | |||
N.ME PCWen/vsb MASatorius MFMejac WDJohnson ABBeach | |||
DATE 06/01/93 06/02/93 06/02/93 06/04/93 06/04/93 | |||
*PM:PDV:NRR l *C:SPLB:DSSA:NRR *D:DSSA:NRR C:OGCB:DORS:NRR D | |||
LEKokaiko CEMcCracken l ACThadani GHMarcus( r lines | |||
06/08/93 1 06/09/93 06/10/93 06//6/93 06/,z/93 DOCUMENT NAME: INTDAFWP.WP 6 | |||
IN 93-xx | |||
June xx, 1993 This information notice requires no specific action or written response. If | |||
you have any questions about the information in this notice, please contact | |||
one of the technical contacts listed below or the appropriate Office of | |||
Nuclear Reactor Regulation (NRR) project manager. | |||
Brian K. Grimes, Director | |||
Division of Operating Reactor Support | |||
Office of Nuclear Reactor Regulation | |||
Technical contacts: Mark A. Satorius, RIV | |||
(817) 860-8141 William D. Johnson, RIV | |||
(817) 860-8148 Peter C. Wen, NRR | |||
(301) 504-2832 Attachments: | |||
1. Figure 1, Existing South Texas Project TDAFWP Steam Supply and Exhaust | |||
System | |||
2. Figure 2, Modified South Texas Project TDAFWP Steam Supply and Exhaust | |||
System | |||
3. List of Recently Issued NRC Information Notices | |||
*SEE PREVIOUS CONCURRENCE | |||
OFFICE *OGCB:DORS *DRP:RIV *TECH ED. *SC:DRP:RIV *D:DRP:RIV | |||
NAME PCWen/vsb MASatorius MFMejac WDJohnson ABBeach | |||
DATE 06/01/93 06/02/93 06/02/93 06/04/93 06/04/93 l | |||
PM PDV:NRR | |||
LEKokaiko | |||
06/1 /93 P | |||
CEMcCI | |||
e | |||
J E | |||
dThadani | |||
BC:OGCB:DORS:NRR | |||
GHMarcus | |||
D:DORS:NRR | |||
BKGrimes | |||
06/ "/93 06/f/L93 06/ /93 06/ /93 DOCUMENT NAME: INTDAFWP.WP | |||
06/04/93 15:05 R I'J US NRC FTS 728-327'3 | |||
002 | |||
06-S12-1119 14t130 ;301 | |||
5 34 37 NRC WHZTEl LINT F | |||
. .1 P.02 IN 93-xx | |||
Junt Xx, 1993 rhis iofwmtion notice requires no specific act on or written response. If | |||
yew ton & questions about the information in his notice, please contact | |||
*a of tochnical contacts listed bolow or th appropriate Office of | |||
btlw lector Regulation (NRR) project manager | |||
Brian K. Gripes, Director | |||
Division of OPerating Reactor Support | |||
Office of Nuclear Reactor Regulation | |||
Toc"ial contatts: MKrk A. Satorius, RI' | |||
(817) 660-4141 William D. Johnton, RIV | |||
(817) B6O-814B | |||
Peter C. Win NRR | |||
(301) 504-28i2 fttocwtsz:1 | |||
1. fig" It Existing South Texas Project TDAfWP Steam Supply and Exhaust | |||
9 t | |||
1. FlKrp 2, Modified South Texas Project TDA4I P Steam Supply and Exhaust | |||
S.stoe | |||
. ist tf Recently Issued NRC Information Noice~s | |||
I Q2I fIaCURR E _.__ I___ | |||
-(, 0 1 93 PCmn/sb tSu:D~ohnn | |||
-/0ul __ 06/02/931 | -/0ul __ | ||
0/P3 | OS 06/02/931 0/P3 / .6. | ||
D OSZiARR 9C OCt!R!OOR$:tRR | CttKn-ANtrRR D OSZiARR 9C OCt!R!OOR$:tRR De:nRS!NRR | ||
- ------- -I | |||
ACHhadani Marcus bKoritme | |||
U- 0r a | |||
:w : 1"TuAokIrP | |||
IN 93-xx | |||
June xx, 1993 Page 3 of | |||
This information notice requires no specific action or written response. If | |||
in this notice, please contact | you have any questions about the information in this notice, please contact | ||
contacts listed below or the appropriate | one of the technical contacts listed below or the appropriate Office of | ||
Nuclear Reactor Regulation (NRR) project manager. | |||
Brian K. Grimes, Director | |||
Division of Operating Reactor Support | |||
Office of Nuclear Reactor Regulation | |||
Technical contacts: Mark A. Satorius, RIV | |||
D | (817) 860-8141 William D. Johnson, RIV | ||
(817) 860-8148 Peter C. Wen, NRR | |||
(301) 504-2832 Attachment: | |||
===List of Recently Issued NRC Information Notices=== | |||
_. __I | |||
D: | OFFICE OGCB:DORS DRP:RIV TECH ED. SC:DRP:RIV D:DRP:RIV | ||
NAME PCWen/vsb MASatorius A. WDJohnson ABBeach | |||
DATE .06/ I /93 _ 06/ /93 06/-L193 f06/ /93 l 06/ /93 | |||
. . .. | |||
BC:SPLB:DSSA:NRR D:DSSA:NRR BC:OGCB:DORS:NRR D:DORS:NRR | |||
ACThadani | CEMcCracken ACThadani GHMarcus BKGrimes | ||
06/ /93 06/ /93 06/ /93 06/ /93 UMUWMMI NAMt: IN IUDAWFW. WF}} | |||
{{Information notice-Nav}} | {{Information notice-Nav}} |
Latest revision as of 04:21, 24 November 2019
r -
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555 July 9, 1993 NRC INFORMATION NOTICE 93-51: REPETITIVE OVERSPEED TRIPPING OF TURBINE-DRIVEN
AUXILIARY FEEDWATER PUMPS
Addressees
nuclear power
All holders of operating licenses or construction permits for
reactors.
Purpose
information
The U.S. Nuclear Regulatory Commission (NRC) is issuing this of turbine- notice to alert addressees to the problem of repetitive tripping
Project Electric
driven auxiliary feedwater pumps (TDAFWPs) at the South Texas the
Generating Station. It is expected that recipients will review
actions, as
information for applicability to their facilities and consider contained in
appropriate, to avoid similar problems. However, suggestions no specific
this information notice are not NRC requirements; therefore, action or written response is required.
Description of Circumstances
On December 27, 1992, Houston Lighting & Power Company (the licensee) receiving a
performed a monthly surveillance test on its Unit 1 TDAFWP. After The
start signal, the pump immediately tripped on an overspeed condition.
local manual
operators repeated the surveillance test after a successful the licensee
start. On this attempt the pump successfully started, and
subsequently considered the pump operable.
water level
On January 23, 1993, Unit 2 tripped from 100-percent power on low
in one of the steam generators. The trip occurred because electro-hydraulic
was lost. The
control oil to the steam generator main feedwater pump turbine longer required.
secured when no
Unit 2 TDAFWP started on demand and was later attempted to
After the pump was secured, problems occurred when operators
from the control room. (See
relatch MOV-514 (the TDAFWP trip/throttle valve) a
The licensee conducted
Figure 1.) The pump was declared inoperable. to resolve the
significant amount of troubleshooting and testing on the TDAFWP was identified
MOV-514 relatch problem and another speed control problem that
was completed
during the testing. After the operability surveillance test was restarted on
successfully, the TDAFWP was declared operable and the unit
January 25, 1993.
a routine monthly
On January 28, 1993, the Unit 1 TDAFWP was tested as part of
immediately tripped on an overspeed
surveillance. When started, the TDAFWP 28 through
condition and was subsequently declared inoperable. From January
9307010233 P PC w3 9t - oSI 915 I
-I
IN 93-51 July 9, 1993 and
January 30, 1993, the licensee undertook an extensive testing with the TDAFWP.
troubleshooting effort to determine the cause of the problem
Several problems (overspeed tripping, Numerous pump starts were completed. full- and inability to maintain rated
lack of speed control, oscillations, the Unit 1 load, steady-state speed) were identified. On January 30, 1993, and
TDAFWP was declared operable following extensive maintenance activities
the successful completion of the surveillance test.
direction of
On February 1, 1993, the Unit 1 TDAFWP was tested again at the considering the
the Unit 1 operations manager in order to ensure operability, signal, the
numerous problems encountered previously. After receiving a start
pump tripped on an overspeed condition and was declared inoperable.
Two steam- On February 3, 1993, Unit 2 was operating at 100-percent power. feedwater
driven steam generator main feedwater pumps and one electric startup
pump were providing feed flow to the steam generators. The startup being
pump tripped when the pump lubricating oil duplex strainers were to avoid
shifted. Operators began to manually ramp down power but were unable
initiated a manual
the low steam generator level. The operators subsequently system trip
reactor trip before receiving an automatic reactor protection Unit 2 signal on low steam generator level. Following the plant trip, the
the steam generators.
TDAFWP received an automatic signal to supply water to
The pump started but immediately tripped on an overspeed condition.
in the
On February 4, 1993, Unit 1 commenced a shutdown to place the reactor had not been
mode required by the Technical Specifications because the TDAFWP
allowed by the
restored to an operable condition within the outage time
Technical Specifications.
NRC
Further details can be found in License Event Report 50-498/93-007 and
Inspection Reports 50-498; 50-499/93-05 and 50-498; 50-499/93-07.
Discussion
Although the licensee did not identify the root cause of the Unit 1 TDAFWP of
overspeed trips, the proximate cause was determined to be the intrusion
water into the TDAFWP turbine that adversely affected its performance.
tests
However, this cause was effectively masked for several surveillance
because the surveillance test program established to satisfy the operability
to
requirements of the Technical Specifications was not sufficiently rigorous conditions.
assure that the testing was performed under suitable environmental
of the
The TDAFWP was not returned to its normal standby condition before each
TDAFWP surveillance tests performed on December 27, 1992, and
normal
January 30, 1993. Because of this, the pump was not tested in its not
standby condition and degraded conditions affecting operability were
revealed.
IN 93-51 July 9, 1993 Unit 2 The licensee determined that the root cause of the February 3, 1993,with an
TDAFWP overspeed trip was an incorrect valve lineup in conjunction
located
Inoperable or degraded steam trap. The valves and the steam trap are TDAFWP
admission line. (See Figure 1.) The
in the drain line from the steam supply
overspeed trip was caused by excessive condensate buildup in the steam
(MOV-514 in Figure 1). The excessive
line upstream of the trip/throttle valve was
condensate had accumulated because the steam trap bypass valve, MS-517, an
the steam trap had degraded to such
incorrectly positioned (closed) and condenser.
extent that it was no longer capable of passing condensate to the
The licensee took the following corrective actions related to the hardware
modifications for both units:
- The trip/throttle valves and governors were sent to the respective
vendors for complete refurbishment and testing. The gearing arrangement
of the trip/throttle valve was modified to ensure slower stroke time, thus enabling a more positive governor response.
- The TDAFWP drain system was modified to remove the steam traps in the
steamline drain system, replacing them with a spool piece. Also, the
trip/throttle valve high-pressure steam leakoff was separated from the
turbine casing drain line and rerouted to the sump to prevent possible
intrusion of steam into the turbine casing. (See Figure 2.)
Related Generic Communications
- NRC Information Notice 86-14, Supplement 2, "Overspeed Trips of AFW,
HPCI, and RCIC Turbines," dated August 26, 1991.
- NRC Information Notice 88-09, "Reduced Reliability of Steam-Driven
Auxiliary Feedwater Pumps Caused by Instability of Woodward PG-PL Type
Governors," dated March 18, 1988.
HPCI,
- IE Information Notice 86-14, Supplement 1, "Overspeed Trips of AFW,
and RCIC Turbines," dated December 17, 1986.
- IE Information Notice 86-14, "PWR Auxiliary Feedwater Pump Turbine
Control Problems," dated March 10, 1986.
.IN
- 93-51 July 9, 1993 If
This information notice requires no specific action or written response.
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts: Mark A. Satorius, RIV
(817) 860-8141 William D. Johnson, RIV
(817) 860-8148 Peter C. Wen, NRR
(301) 504-2832 Attachments:
1. Figure 1, Existing South Texas Project
TDAFWP Steam Supply and Exhaust System
2. Figure 2, Modified South Texas Project
TDAFWP Steam Supply and Exhaust System
3. List of Recently Issued NRC Information Notices
MOV-143 STEAM EXHAUST
LINE
STEAM ADMISSION
LINE
MOV-514 TERRY
TURBINE (
STEAM ADMISSION PIPE CAP WITH ORIFICE
LINE DRAIN If (UNIT I ONLY)
VALVES
MS
371 MS
370 MS TURBINE CASING
FO 7537B 373 DRAIN VALVE
~1 II
STEAM TRAP STEAM FO 7537A--
BYPASS
VALVE
TRAP
Yl (D% %Dn
w I1
°% I'-
CONDENSER I-a%0 w r
0D
FIGURE 1 TDAFWP STEAM SUPPLY AND EXHAUST SYSTEM (UNMODIFIED)
MOV-143 STEAM EXHAUST
LINE
STEAM ADMISSION
LINE
MOV-514 TERRY
TURBINE C
STEAM ADMISSION
UNE DRAIN
VALVES
MS
370 MS TURBINE CASING
FO 7537B 373 DRAIN VALVE
MS
515 STEAM TRAP SPOOL
BYPASS PIECE m'z ~ --
VALVE
MS " MD3%Dt
HAQ
516 %O D
CONDENSER " D
Wa "
FIGURE 2 TDAFWP STEAM SUPPLY AND EXHAUST SYSTEM (MODIFED)
Attachment 3 IN 93-51 July 9, 1993 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information Date of
Notice No. Subject Issuance Issued to
93-50 Extended Storage of 07/08/93 All licensees authorized
Sealed Sources to possess sealed sources.
93-49 Improper Integration of 07/08/93 All holders of OLs or CPs
Software into Operating for nuclear power reactors.
Practices
93-48 Failure of Turbine- 7/6/93 All holders of OLs or CPs
Driven Main Feedwater for nuclear power reactors.
Pump to Trip Because of
Contaminated Oil
92-06, Reliability of ATWS 07/01/93 All holders of OLs or CPs
Supp. 1 Mitigation Systems and for nuclear power reactors.
Other NRC-Required Equip- ment not Controlled by
Plant Technical Specifica- tion
93-47 Unrecognized Loss of 06/18/93 All holders of OLs or CPs
Control Room Annunciators for nuclear power reactors.
93-46 Potential Problem with 6/10/93 All holders of OLs or CPs
Westinghouse Rod Control for Westinghouse (W)-
System and Inadvertent designed nuclear power
Withdrawal of A Single reactors.
Rod Control Cluster Assembly
93-45 Degradation of Shutdown 06/16/93 All holders of OLs or CPs
Cooling System Performance for nuclear power reactors.
93-44 Operational Challenges 06/15/93 All holders of OLs or CPs
During A Dual-Unit for nuclear power reactors.
93-43 Use of Inappropriate 06/10/93 All holders of OLs or CPs
Lubrication Oils in for nuclear power reactors.
Safety-Related Applications
OL = Operating License
CP - Construction Permit
\,-
IN 93-51 July 9, 1993 This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
orig /s/'d by BKGrimes
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts: Mark A. Satorius, RIV
(817) 860-8141 William D. Johnson, RIV
(817) 860-8148 Peter C. Wen, NRR
(301) 504-2832 Attachments:
1. Figure 1, Existing South Texas Project TDAFWP
Steam Supply and Exhaust System
2. Figure 2, Modified South Texas Project
TDAFWP Steam Supply and Exhaust System
3. List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCE
OFFICE *OGCB:DORS *DRP:RIV *TECH ED. *SC:DRP:RIV *D:DRP:RIV
NAME PCWen/vsb l MASatorius MFMejac WDJohnson ABBeach
DATE 06/01/93 l 06/02/93 06/02/93 06/04/93 06/04/93
- PM:PDV:NRR *C:SPLB:DSSA:NRR *D:DSSA:NRR *C:OGCB:DORS:NRR D
LEKokaJko CEMcCracken ACThadani GHMarcus dd____
06/08/93 06/09/93 06/10/93 06/16/93 DOCUMENT NAME: 93-51.IN
IN 93-xx
June xx, 1993 This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts: Mark A. Satorius, RIV
(817) 860-8141 William D. Johnson, RIV
(817) 860-8148 Peter C. Wen, NRR
(301) 504-2832 Attachments:
1. Figure 1, Existing South Texas Project TDAFWP Steam Supply and Exhaust
System
2. Figure 2, Modified South Texas Project TDAFWP Steam Supply and Exhaust
System
3. List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCE
OFFICE *OGCB:DORS *DRP:RIV *TECH ED. *SC:DRP:RIV *D:DRP:RIV
N.ME PCWen/vsb MASatorius MFMejac WDJohnson ABBeach
DATE 06/01/93 06/02/93 06/02/93 06/04/93 06/04/93
- PM:PDV:NRR l *C:SPLB:DSSA:NRR *D:DSSA:NRR C:OGCB:DORS:NRR D
LEKokaiko CEMcCracken l ACThadani GHMarcus( r lines
06/08/93 1 06/09/93 06/10/93 06//6/93 06/,z/93 DOCUMENT NAME: INTDAFWP.WP 6
IN 93-xx
June xx, 1993 This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts: Mark A. Satorius, RIV
(817) 860-8141 William D. Johnson, RIV
(817) 860-8148 Peter C. Wen, NRR
(301) 504-2832 Attachments:
1. Figure 1, Existing South Texas Project TDAFWP Steam Supply and Exhaust
System
2. Figure 2, Modified South Texas Project TDAFWP Steam Supply and Exhaust
System
3. List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCE
OFFICE *OGCB:DORS *DRP:RIV *TECH ED. *SC:DRP:RIV *D:DRP:RIV
NAME PCWen/vsb MASatorius MFMejac WDJohnson ABBeach
DATE 06/01/93 06/02/93 06/02/93 06/04/93 06/04/93 l
PM PDV:NRR
LEKokaiko
06/1 /93 P
CEMcCI
e
J E
dThadani
BC:OGCB:DORS:NRR
GHMarcus
D:DORS:NRR
BKGrimes
06/ "/93 06/f/L93 06/ /93 06/ /93 DOCUMENT NAME: INTDAFWP.WP
06/04/93 15:05 R I'J US NRC FTS 728-327'3
002
06-S12-1119 14t130 ;301
5 34 37 NRC WHZTEl LINT F
. .1 P.02 IN 93-xx
Junt Xx, 1993 rhis iofwmtion notice requires no specific act on or written response. If
yew ton & questions about the information in his notice, please contact
- a of tochnical contacts listed bolow or th appropriate Office of
btlw lector Regulation (NRR) project manager
Brian K. Gripes, Director
Division of OPerating Reactor Support
Office of Nuclear Reactor Regulation
Toc"ial contatts: MKrk A. Satorius, RI'
(817) 660-4141 William D. Johnton, RIV
(817) B6O-814B
Peter C. Win NRR
(301) 504-28i2 fttocwtsz:1
1. fig" It Existing South Texas Project TDAfWP Steam Supply and Exhaust
9 t
1. FlKrp 2, Modified South Texas Project TDA4I P Steam Supply and Exhaust
S.stoe
. ist tf Recently Issued NRC Information Noice~s
I Q2I fIaCURR E _.__ I___
-(, 0 1 93 PCmn/sb tSu:D~ohnn
-/0ul __
OS 06/02/931 0/P3 / .6.
CttKn-ANtrRR D OSZiARR 9C OCt!R!OOR$:tRR De:nRS!NRR
- ------- -I
ACHhadani Marcus bKoritme
U- 0r a
- w : 1"TuAokIrP
IN 93-xx
June xx, 1993 Page 3 of
This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts: Mark A. Satorius, RIV
(817) 860-8141 William D. Johnson, RIV
(817) 860-8148 Peter C. Wen, NRR
(301) 504-2832 Attachment:
List of Recently Issued NRC Information Notices
_. __I
OFFICE OGCB:DORS DRP:RIV TECH ED. SC:DRP:RIV D:DRP:RIV
NAME PCWen/vsb MASatorius A. WDJohnson ABBeach
DATE .06/ I /93 _ 06/ /93 06/-L193 f06/ /93 l 06/ /93
. . ..
BC:SPLB:DSSA:NRR D:DSSA:NRR BC:OGCB:DORS:NRR D:DORS:NRR
CEMcCracken ACThadani GHMarcus BKGrimes
06/ /93 06/ /93 06/ /93 06/ /93 UMUWMMI NAMt: IN IUDAWFW. WF