Information Notice No. 83-46: Common-mode Valve Failures Degrade Surry's Recirculation Spray Subsystem
SSINS No.: 6835
IN 83-46
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C., 20555
July 1, 1983
Information Notice No. 83-46: COMMON-MODE VALVE FAILURES DEGRADE
SURRY'S RECIRCULATION SPRAY SUBSYSTEM
Addressees:
All nuclear power reactor facilities holding an operating license (OL) or a
construction permit (CP).
Purpose:
The primary purpose of this notice is to inform licensees and holders of CPs
of the apparent common-mode failures that affected the valves which admit
service water to the recirculation spray coolers at the Surry Power Station.
Seven of eight motor-operated, 30-in. butterfly valves (four on Unit 1 and
three on Unit 2) failed to open during surveillance tests of the
recirculation spray subsystem. (See Figure 1, "Service Water System" for the
valves that failed to open). The recirculation spray subsystem not only
cools and depressurizes the containment following a postulated
loss-of-coolant accident (LOCA), it also removes heat from water which is
injected into the core by the low pressure safety injection system. These
failures, therefore, jeopardized the plant's ability to mitigate the effects
of a LOCA. (See Figure 2, "Engineered Safeguards Systems" for the
interfacing of the recirculation spray subsystem with the emergency core
cooling system.)
A secondary purpose of this notice is to alert licensees and holders of CPs
of the susceptibility to common-mode failures of other components or systems
using brackish and/or silty service water. Such service water can cause
components to fail by plugging resulting from marine growth or silt deposit,
by leaking resulting from corrosion or erosion, or by a combination of these
effects. Failures of components using such service water have been
experienced at several facilities. For example, Salem has experienced about
75 service water related events since 1980. In addition, the issuance of IE
Bulletin 80-24 was precipitated by an Indian Point 2 event in 1980 which
flooded the containment building with service water. (See Table 1 for a
partial listing of LERs issued since 1980 involving failures or degradation
of components attributed to hostile service water systems.)
System Description:
The recirculation spray subsystem at the Surry Power Station is designed to
mitigate the effects of a postulated LOCA during the recirculation phase of
the recovery (i.e., after the water in the refueling water storage tank has
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IN 83-46
July 11, 1983
Page 2 of 4
been nearly depleted). This is accomplished by returning the containment
pressure to a subatmospheric value following a LOCA and by providing for
long term heat removal and maintaining the containment at subatmospheric
conditions. The extended loss of the recirculation spray subsystem
subsequent to a LOCA, therefore, could result in the loss of the ultimate
heat sink.
Primary coolant water and emergency core cooling water spilled from a
postulated LOCA and the water from the containment spray system would
collect in the containment sump. While in the recirculation mode, the
containment sump water would be diverted to two subsystems: (1) the low head
safety injection subsystem, and (2) the recirculation spray subsystem. Water
from the low head safety injection subsystem would be returned to the
reactor to cool the core. Water from the recirculation spray subsystem would
cool and depressurize containment by the heat removal function of the four
recirculation spray coolers. The recirculation spray coolers would not only
cool the containment spray water but would also cool the water being
returned to the reactor. However, before these coolers can cool the
containment and remove the decay heat, at least one of the four normally
closed valves that admit service water to the coolers must be opened.
Description of Circumstances:
On February 9, 1983, the Surry Unit 1 recirculation spray subsystem was
being tested while the unit was shut down with the reactor coolant
temperature and pressure less than 350F and 450 psig. This test
involved the flushing of the four recirculation spray heat exchangers by
opening four normally closed motor-operated valves. Opening these 30-in.
butterfly valves permits service water to flow through the recirculation
spray heat exchangers. However, during this particular test, all four valves
failed to open. Because of these failures, the Unit 2 valves that admit
service water to the recirculation spray coolers were also tested on
February 9, 1983 while Unit 2 was operating at 100% power. Three of the four
normally closed motor-operated valves failed to open during this test;
however, since opening of only one valve will provide service water to all
four coolers, the recirculation spray subsystem was operable.
After the four Unit 1 valves failed to open, each was manually opened by
using the valve's hand wheel. Significant torque was required to lift the
butterfly discs off their seats. The fact that each valve's failure to open
resulted in the tripping of its motor overload device indicates that
significant torque would be required to open the valves. After the valves
had been manually opened, two responded to the electrical signals from the
control room and two failed to respond. As a consequence, the licensee was
unable to determine the exact causes of the initial failures for those
valves that subsequently responded to the electrical signals. The cause of
failures of those that did not respond to the electrical signals was listed
as corrosion (one bad a corroded motor, the other a corroded torque switch).
Although the exact cause or causes for these failures has not been
determined, they have been attributed to several factors, or a combination
thereof, including:
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IN 83-46
July 11, 1983
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o Marine growth - barnacles, shells, silt and seagrowth were found
on the valve seats and discs;
o Corrosion - two valves failed to open because of a corroded motor
and another because of a corroded torque switch. The corrosion
appears to be due to either the flooding of the valve bit area
that occurred several years ago or to the high moisture content in
the valve pit area;
o Infrequent testing - these valves had been only stroke-tested
during refueling outages (i.e., approximately every 18 months);
o Low torque switch settings - two Unit 2 valve operators "torqued
out" when tested; and
o Marginally sized motors and/or improperly geared valve operators.
Corrective actions taken by the licensee include:
o Cleaning the piping and valve internals;
o Applying marine inhibitor paint on the valve discs;
o Testing the valves quarterly rather than during refueling outages.
(Note: The Unit 1 valves operated properly during subsequent
testings, but one Unit 2 valve failed to open during subsequent
testing because of a low torque switch setting.);
o New motor operators having increased torque output have been
engineered and one such operator is being tested at the plant
before installing eight such operators. In the interim, the
torque switch settings of the installed operators have been
increased; and
o Administrative controls - responsibility for the proper operation
of these valves has been specifically assigned to a knowledgeable
person on each shift. This person is responsible for ensuring the
proper operation of these valves during accident conditions by
going to the valve pit area and manually opening the valves, if so
required.
In addition, prior to this event but subsequent to the above mentioned
flooding of the valve pit area, metal dikes had been constructed, around the
valve pits and water level detectors had been installed to prevent or detect
flooding of these valves.
No written response to this notice is required; however, it is suggested
that licensees and holders of construction permits review this information
for applicability at their facilities.
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IN 83-46
July 11, 1983
Page 4 of 4
If you have any questions regarding this matter, please contact the Regional
Administrator of the appropriate NRC Regional Office, or the Technical
Contact listed in this notice.
Edward L. Jordan Director
Division of Emergency Preparedness
and Engineering Response
Office of Inspection and Enforcement
Technical Contact: I. Villalva, IE
(301) 492-9365
Attachments:
1. Figure 1, Service Water System
2. Figure 2, Engineered Safeguards Systems
3. Table 1
4. List of Recently Issued Information Notices
.
Attachment 3
IN 83-46
July 11, 1983
Page 1 of 8
TABLE 1
Abstracted List of LERs Issued Since 1980 Involving Component Failures or
Degradation Due to the Effects of Hostile Service Water Systems
LER NO. Event Cause
82-149 One service water loop inoperable Grassy debris and silt had
at Salem 2 plugged the strainer
82-155 Containment fan coil unit (CFCU) Silt buildup in CFCU
inoperable at Salem 2
82-136 CFCU inoperable at Salem 2 Tubing eroded by silt
82-091 Numerous SW piping welds fails at Corrosive environment of
Salem 1 the service water system
82-130 CFCU inoperable at Salem 2 Silt in control valves
82-135 CFCU inoperable at Salem 2 Tubing erosion due to silt
82-115 Diesel generator inoperable at Erosion of SW pipe due to
Salem 2 silt
82-086 SW pump inoperable at Salem 2 Erosion and corrosion of oil
cooler
82-075 CFCU inoperable at Salem 2 SW tubing erosion due to silt
82-074 CFCU inoperable at Salem 2 SW tubing erosion due to silt
82-105 CFCU inoperable at Salem 2 Silt buildup in cooling coils
82-109 CFCU inoperable at Salem 2 Coils eroded by silt
82-119 CFCU inoperable at Salem 2 Erosion of coils by silt
82-120 CFCU inoperable at Salem 2 Erosion of tubing by silt
82-098 CFCU inoperable at Salem 2 Silt buildup in cooling coils
82-099 CFCU inoperable at Salem 2 Silt buildup in cooling coils
82-100 CFCU cooling coil leaks at Salem 2 Erosion of coils by silt
82-096 CFCU inoperable at Salem 2 Silt buildup in cooling coils
82-092 CFCU inoperable at Salem 2 Erosion of motor cooling coils
82-091 CFCU inoperable at Salem 2 Coil erosion
82-073 CFCU inoperable at Salem 2 Erosion of cooling coils by
silt
82-074 CFCU inoperable at Salem 2 Erosion of cooling coils by
silt
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Attachment 3
IN 83-46
July 11, 1983
Page 2 of 8
TABLE 1 (CONTINUED)
LER NO. Event Cause
82-061 CFCU inoperable due to erratic SW Silt in sensing line
flow indication at Salem 1
82-080 CFCU inoperable at Salem 2 Erosion of copper nickel
cooling coils
82-084 CFCU Inoperable at Salem 2 Erosion of copper nickel
cooling coils
82-070 CFCU inoperable at Salem 2 Erosion of tubing by silt
particles
82-065 CFCU inoperable at Salem 2 Valve actuator failed due to
corrosion
82-058 CFCU inoperable at Salem 2 Valve plugged by oysters
82-050 3 CFCU's inoperable at Salem 2 Oysters plugged SW valve
82-037 Service water flow to CFCU Valve stuck in closed position
insufficient at Salem 1
82-040 SW piping to CFCU leaks at Salem 2 Eroded blank flange
82-041 Low SW flow to CFCU at Salem 2 Oyster plugging tube bundle
82-046 Low SW flow to CFCU at Salem 2 Oyster plugging tube bundle
82-029 CFCU inoperable due to low service Flow control valve stuck closed
water flow at Salem 1
82-038 CFCU inoperable at Salem 2 Flow transmitter plugged with
silt
82-028 Update on CFCU leak at Salem 2 Leaky flange
82-024 CFCU inoperable at Salem 1 SW flow control valve stuck
closed
81-092 CFCU leaks at Salem 1 Coil failure
81-115 Update on CFCU leakage at Salem 2 Coil leakage
81-114 CFCU (motor cooler) leakage Not stated
exceeds limit at Salem 2
81-117 Two CFCU's inoperable due to Defective limit switch and silt
position and flow sensor problems in line
at Salem 2
81-121 SW leak in containment at Salem 1 Leaky spool piece between 2
valves
81-109 CFCU inoperable at Salem 1 Coil failure
81-108 CFCU inoperable at Salem 1 Coil failure
81-119 Charging pump inoperable at Corrosion causes SW line to
Salem 1 leak
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Attachment 3
IN 83-46
July 11, 1983
Page 3 of 8
TABLE 1 (CONTINUED)
LER NO. Event Cause
81-114 CFCU inoperable at Salem 1 Coil failure
81-115 CFCU inoperable at Salem 2 Coil leak
81-094 CFCU leak rate exceeds limit at Two coil leaks
Salem 1
81-110 2 CFU's inoperable at Salem 2 Silt in instrument line
81-096 2 CFCUs leak at Salem 1 Coil leaks
81-103 CFCU inoperable at Salem 2 Transmitter plugged with silt
81-086 CFCU service water flow sensor Transmitter plugged with silt
fails twice at Salem 1
81-094 CFCU leaks at Salem 2 Primary coil failure
81-099 Low SW flow to CFCU at Salem 2 Flow sensor clogged with silt
81-084 CFCU leaks at Salem 1 Leaky cooling coil
81-083 ECCS subsystem inoperable at SW leak due erosion and
Salem 1 corrosion
81-080 CFCU inoperable at Salem 1 Hole in weld on pipe flange
81-090 CFCU leaks at Salem 2 Primary coil failure
81-076 CFCU leaks at Salem 1 Secondary coil failure
81-077 CFCU leaks at Salem 1 Secondary coil failure
81-074 CFCU leaks at Salem 1 Secondary coil failure
81-078 CFCU leaks at Salem 1 Secondary coil failure
81-064 CFCU leaks twice at Salem 2 Weld failures
81-071 Inadequate SW flow to CFCU at Flow transmitter plugged with
Salem 1 silt
81-075 CFCU inoperable at Salem 1 SW transmitter filled with silt
81-072 SW leaks found in CFCU at Salem 1 Cooling coil failure
81-055 CFCU SW flow sensor fails at Transmitter clogged with silt
Salem 2
81-064 CFCU pipe welds leak at Salem 1 Cracked weld to dissimilar
metals
81-039 CFCU leaks at Salem 1 Crack in weld
81-011 CFCU inoperable at Salem 1 Leak in service water pipe weld
.
Attachment 3
IN 83-46
July 11, 1983
Page 4 of 8
TABLE 1 (CONTINUED)
LER NO. Event Cause
81-010 CFCU inoperable at Salem 1 Leak in service water pipe
81-003 Component cooling system Leaky service water pipe welds
inoperable at Salem 1
80-049 Charging pump inoperable at Leak in service water piping
Salem 1
82-132 RHRSW loop inoperable at Hatch 2 A pin hole leak developed in
the valve body via internal
erosion
83-014 SW header leaks at North Anna 2 Aggressive water and bacterial
reduction
82-064 Containment spray system Heat exchanger fouling due to
inoperable at Oyster Creek inadequate service water
chlorination
83-001 Car fan cooler leaks at Conn. Corrosion or Erosion of coils
Yankee
83-081 SW header inoperable at North Pinhole leak due to aggressive
Anna 1 water
82-065 Service water pump fails to Corroded steel stud
develop discharge pressure at
Surry 2
82-113 RHRSW pump inoperable at Hatch 2 Corroded discharge valve
flapper shaft
82-040 Reactor shutdown due to hich CFCU High liquid waste disposal
leakage at indian point 2 system burden
82-073 Service water isolation valve Unknown
fails to close at Surry 2
82-000S Reactor shutdown due to high Biofouling of containment spray
water system delta P at Oyster heat exchangers
Creek
82-037 Two containment fan coolers leak Unknown
at Indian Point 2
82-050 Low service water system pressure High SW use and a clogged
occurs at Surry 2 strainer
82-062 RHR service water pump fails flow Silt in Suction bell
test at Hatch 1
82-031 Service water hoses leak in Corrosion
containment at Indian Point
82-054 RHRSW pump fails at Hatch 1 Unknown, (silt mentioned)
82-035 Drain valve broken off SW heat Corrosion
exchanger line at Calvert Cliffs 2
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Attachment 3
IN 83-46
July 11, 1983
Page 5 of 8
TABLE 1 (CONTINUED)
LER NO. Event Cause
82-014 ESW pump fails to meet discharge Mussels, clam, marine growth in
pressure at Millstone 1 pump
82-067 Charging pump SW pump fails to Trash in strainer
develop sufficient pressure at
Surry 1
80-027 Update on river water check valve Pin erosion due to high flow
failure at Beaver Valley 1
81-071 Service water supply header leaks Corrosion
twice at North Anna 1
82-046 RHRSW pumps fail at Hatch 1 Debris lodged in pump impellers
82-044 RHRSW pump fails to meet flow Crud in pump
requirements at Hatch 2
82-047 RHRSW pump inoperable due to high Leaky gland led to bearing
vibration at Brunswick 1 corrosion
82-032 Two RHRSW pumps inoperable at Leaky check valve and eroded
Arnold set screw allowed hinge pin to
loose and valve to move proper
seat
82-019 Service water radiation monitor Crud in suction line
pump fails at Surry 2
82-053 Two service water radiation Sediment in suction lines
monitor pumps inoperable at
Surry 1
82-009 AFWS pump cooler service water Silt accumulation
valves fail to open at Zion 2
82-010 SW header leaks at Millstone 2 Corrosion
82-006 SW header leaks at North Anna 1 Corrosion
82-008 Letdown cooler leaks at Crystal Tube to shell leak
River 3
82-035 RHRSW pressure transmitter fails Corrosion of module diaphragm
at Brunswick 1
81-077 Service water radiation monitor Sediment in pump
pump fails at Surry 2
82-008 Three valves inoperable due to Service water leak penetrated
water leakage at millstone 1 motor control center
82-002 Containment cooling system Marine fouling at SW pump
inoperable at Millstone 1 suction
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Attachment 3
IN 83-46
July 11, 1983
Page 6 of 8
TABLE 1 (CONTINUED)
LER NO. Event Cause
82-035 LPSI pump inoperable at ANO-2 Corrosion products in SW pipe
81-076 Service water inlet valve fails to Unknown
operate at Surry 2
82-027 Containment spray heat exchanger Fresh water clams on ERCW inlet
inoperable at Sequoyah 1 screen
82-011 Service water piping leaks at Erosion due to valve throttling
Cook 2
82-009 Service water piping leaks at Erosion due to valve throttling
Cook 1
82-009 Charging pump inoperable at Foreign object in valve
Surry 2
82-005 RHR shutdown cooling and Plugged sensing lines and
suppression pool cooling fails maintenance errors
when demanded at Brunswick 2
81-074 RHRSW subsystem inoperable due Crud in motor cooler due to
to high pump motor temperature corrosion
at Brunswick 1
81-083 Service water supply header leaks Corrosion
at North Anna 1
81-123 RHRSW pump inoperable at Hatch 1 Crud in motor cooling water
line
81-024 Containment pipeway air cooler Corrosion in coils
leaks at Big Rock Point
81-062 Three service water radiation Sediment accumulation
monitor pumps fail to operate
at surry 2
81-021 SW outlet line from fan cooler Pin hole leak in pipe
motor cooler leaks at Indian
Point 2
81-089 Plant SW pump fails to maintain Debris lodged in pump
flow and pressure at Hatch 1
81-053 SW pump rotates backwards at Check valve failed to seat
Surry 2 properly
80-030R Update on displaced RHR heat Accumulation or marine growth
exchanger baffle at Brunswick 2 shells
81-084 Plant service water stainer Clogged strainer damaged during
at Hatch 1 cleaning
81-023 Service water pump discharge line Corrosion
leaks at Millstone 2
81-024 2 service water pumps Inoperable Clogged pump suction bells
at Oyster Creek
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Attachment 3
In 83-46
July 11, 1983
Page 7 of 8
TABLE 1 (CONTINUED)
LER NO. Event Cause
81-066 Standby SW system fails to deliver Crud blocking flow into pump
rated flow to diesel at Hatch 2
81-063 RHRSW pump fails test at Hatch 2 Crud lodged in pump
81-041 Recirculation spray SW radiation Service water crud on pump
internals monitoring pump fails
at Surry 2
81-009 CCW heat exchanger and valve flow Barnacle growth
blocked at San Onofre 1
81-011 Exterior surface of SW pump Corrosion
discharge piping pitted at Indian
Point 2
81-096 SW supply header leaks at North Reducing Bacteria
Anna 1 & 2
81-017 Containment spray loop inoperable SW loop out due to sea lettuce
at Oyster Creek in canal
81-024 Service water supply header Unknown (suspect leak caused by
at North Anna 1 and 2 sulfate reducing bacteria
within the SW piping)
81-021 Room chiller removed from service Clogged condenser SW strainer
at Surry 2
81-017 Diesel generator trips on high Deposit of impurities in
cooling water temperature at Ft. service water on valve stem
St. Vrain caused valve to stick closed or
nearly closed
81-010 Service water pump develops low Eel lodged in impeller
discharge pressure at Surry 2
81-007 RHR service strainer plugs up at Sand lodged in mesh
Duane Arnold
81-005 Service water pump suction Clogged pump suction strainer
pressure low Oyster Creek
81-007 Generator oil cooler leaks at A sacrificial zinc anode had
Millstone 2 corroded resulting in service
water leakage
81-010 RHRSW system inoperable at Suction valve would not open
Brunswick 2 fully
80-037 Charging pump service water Clogged pump inlet strainer and
pressure drops and is not alarmed sensing line
at Surry 2
80-029 Service water pump develops low Eel in impeller
discharge pressure at Surry 2
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Attachment 3
IN 83-46
July 11, 1983
Page 8 of 8
TABLE 1 (CONTINUED)
LER NO. Event Cause
80-006 Screen wash pump discharge valve Corrosion and erosion
leaks at Humboldt Bay 3
80-018 Charging pump service water pump Material entrained, on suction
inoperable at Surry 2 side of pump
80-035 Insufficient SW flow in reactor Asian clam buildup in service
buildup cooling coils at ANO-1 water cooler
80-027 RHRSW check valve fails to seat Degradation of valve internals
at Vermont Yankee
80-065 SW valve fails to open at Surry 1 Marine growth suspected
80-052 SW heat exchanger inoperable at Tube leak in #2 saltwater/
Calvert Cliffs 2 service water heat exchanger
80-072 Containment building coolers SW Buildup of Asian clams in SW
flow inadequate at ANO-2 side of cooler
80-018 HPSW Pump inoperable at Oconne 1 Motor cooler tube leaks due to
erosion and corrosion
80-103 Both SW trains inoperable at Strainers were partially
Hatch 1 restricted
80-032 SW heat exchanger outlet valve Corroded piston rod
fails to open fully at Calvert
Cliffs 1
80-022 High pressure SW pump cooler tube Erosion and corrosion
leak at Oconne 1
80-004 High pressure SW pump motor Erosion from flow of Lake water
cooler leaks at Oconne 1
80-024 RHR service water pump flow drops Debris drawn into pump suction
suddenly at Hatch 2
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