United States Nuclear Regulatory Commission - Protecting People and the Environment

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 


8306270401 
.

                                                              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: 
.

                                                              IN 83-46     
                                                              July 11, 1983 
                                                              Page 3 of 4  

     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. 
.

                                                              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 
.
                                                              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 
.
                                                              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 
.
                                                              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 
.
                                                              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  
.
                                                            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  
.
                                                              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 
.
Page Last Reviewed/Updated Tuesday, November 12, 2013