United States Nuclear Regulatory Commission - Protecting People and the Environment

ACCESSION #:  9505030198

                              Public Service
                              Electric and Gas
                              Company

Stanley LaBruna     Public Service Electric and Gas Company
                    P.O. Box 236, Hancocks Bridge, NJ 08038 
609-339-1700

Vice President-Nuclear Engineering

                               APR 26 1995
                                LR-N95059

United States Nuclear Regulatory Commission
Document Control Desk
Washington, DC 20555

Gentlemen:

10CFR21 NOTIFICATION
ANCHOR DARLING VALVE COMPANY SWING CHECK VALVES 
HOPE CREEK GENERATING STATION
DOCKET NO. 50-354

In accordance with the requirements of 10CFR21, Public Service
Electric
and Gas (PSE&G) hereby provides the attached report concerning
the hinge
arms associated with sixteen swing check valves manufactured by
Anchor-
Darling Valve Company.  The initial 10CFR21 notification was
provided to
the NRC Operations Center on March 29, 1995.  The attachment
fully
describes the identified deficiency and corrective actions
planned and
implemented.

Please do not hesitate to contact us if there are any questions
regarding
this submittal.

                              Sincerely,

Attachment


Document Control Desk               2
LR-N95059                                              APR 26
1995

C    Mr. T. T. Martin, Administrator - Region I 
     U. S. Nuclear Regulatory Commission
     475 Allendale Road
     King of Prussia, PA 19406

     Mr. David H. Moran
     Licensing Project Manager - Hope Creek
     U. S. Nuclear Regulatory Commission
     One White Flint North
     11555 Rockville Pike
     Mail Stop 14E21
     Rockville, MD 20852

     Mr. R. Summers (S09)
     USNRC Senior Resident Inspector

     Mr. K. Tosch, Manager, IV
     NJ Department of Environmental Protection
     Division of Environmental Quality
     Bureau of Nuclear Engineering
     CN 415
     Trenton, NJ 08625


LR-N95059

                              ATTACHMENT 1

I.   BACKGROUND

In November, 1994, 12" Core Spray Pump "B" discharge check valve
1BEV-015
failed to close during performance of procedure OP-IS.BE-002(Q). 
Inspection of the valve determined that the valve disc contacted
the body
in such a way as to pinch the disc causing it to stick in the
open
position for a short period of time.  The valve design includes a
butt
stop hinge to prevent the disc from contacting the valve body. 
Based on
the inspection, it was determined that the butt stop on the hinge
arm was
not contacting the valve body to prevent disc-to-body contact
(See
Enclosure 1 - Schematic from Anchor-Darling Valve Co.,
Williamsport,
Pa.).  To correct the deficiency, a new butt stop hinge arm,
hinge pin
and disc were installed, and the valve successfully retested in
accordance with the surveillance test procedure.

As a result, PSE&G initiated inspections of Anchor-Darling check
valves
with a similar hinge style to determine if a generic type
deficiency
exists.  A total of 15 additional valves were identified that may
be
affected as listed in Enclosure 3.  On 1/19/95, 20" Station
Auxiliary
Cooling System (SACS) "D" pump check valve 1EGV-019 was inspected
as a
result of the Core Spray check valve failure corrective actions. 
The
inspection revealed that the valve disc was knocking against the
valve
body in two places with the valve in the open position.  Although
this
valve had not failed, it was apparent that the butt stop feature
was
inadequate.  The valve hinge arm and disc were replaced, and the
new
hinge arm was modified per the vendor instructions to build up
material
on the butt end.

On March 29, 1995, PSE&G reported this deficiency to the NRC in
accordance with 10CFR21.  The inadequate butt stop feature may
not
preclude disc-to-body contact resulting in disc pin failure or
the valves
sticking in the open position.

On April 10, 1995, PSE&G inspected SACS "C" pump discharge check
valve
1EGV-013 to ensure sufficient spacing between the valve disc and
body
when in the open position.  Again, disc-to-body contact was
identified
with no failure (Same as SACS "D" pump check valve).  The valve
was
repaired by weld build-up to the hinge arm butt and reassembled
using the
original hinge arm, disc and hinge pin.

PSE&G has reviewed the maintenance history of the other similar
check
valves.  One previous Anchor-Darling check valve (FPCC Pump

                              Page 1 of 11


LR-N95059
                          ATTACHMENT 1 (cont'd)

discharge check valve 1ECV-007) of similar design was found to
have stuck
in the open position due to the hinge butt pinching against the
body. 
This occurred on three (3) separate occasions in 1988 and 1989. 
The
final resolution was to grind the hinge butt.  No problems have
been
identified to date with this valve since the corrective actions
were
completed.

II.  EVALUATION

PSE&G evaluation of this deficiency has identified that
fracturing of
swing check valve disc pins in the industry has occurred.  The
failures
have been attributed to the direct impact of the valve disc on
the body
during opening.  Repeated occurrences of this impact due to
operation
and/or disc flutter has contributed to pin failures. 
Anchor-Darling
modified its swing check valve design in the 1980 time frame by
adding an
extended hinge tail stop to absorb the impact during valve
opening
instead of the butt stop design installed in 16 check valves at
Hope
Creek (See Enclosure 2).  This modification addressed the
potential pin
failure concern.  Anchor-Darling has recommended replacement of
the older
hinge arm design.  PSE&G is repairing the present hinge arms
typically by
weld build-up, as warranted to prevent disc-to-body contact, and
is
evaluating if replacement of the hinge arms with the new design
is
required.

PSE&G has concluded that the deficiency in the hinge arm
tolerances that
relies on the older butt stop design may not preclude
disc-to-body
contact (as was the case with the Core Spray and SACS check
valves). 
Variations in the valve body casting profiles that occur during
manufacturing or location of the hinge during assembly could also
contribute to reduced clearance between the disc and body
resulting in
contact.  Disc-to-body contact could result in two types of
failure modes
check valves; (1) disc pin failure due to fatigue from the impact
of the
disc against the valve body or disc flutter, the potential for
the valves
to stick in the open position the butt stop or the valve disc
becoming
wedged against the valve body.  The two failure modes create
different
operational concerns.  Disc pin failure could result in

disassociation of
the valve disc from the hinge.  The unattached disc could become
wedged
in the valve body or down stream piping resulting in the partial
or
complete blockage of an essential flow path.  For the second
failure
mode, pump runout could occur for parallel pump loops (i.e. Core
Spray
System) due to failure of the opposite pump discharge check valve
to
close and the loss of the associated pump.  This failure mode
could also
result in a loss to the Keep Fill systems associated with the
Core Spray
System and Residual Heat Removal (RHR) System.  The Keep Fill
systems

                              Page 2 of 11


LR-N95059
                          ATTACHMENT 1 (cont'd)

prevent a potential water hammer event due to pump start that
could
result in the loss of the loop or piping failure.  Based on the
above,
PSE&G has concluded that the existing hinge arms installed at
Hope Creek
could be considered a Substantial Safety Hazard as defined by
10CFR21
should similar dimensional tolerance deficiencies exist in the
remaining
valves that have yet to be inspected.  Therefore, this issue is
reportable in accordance with 10CFR21.

Engineering Evaluation (EE) H-1-ZZ-MEE-0984 was performed to
address the
two failure modes above and the specific impact these failures
could have
at Hope Creek.  The EE concluded that the subject deficiency is
not
considered an immediate operability concern for the following
reasons:

Disc Pin Failure

No disc pin failures have been identified in the sixteen check
valves to
date.  The disc pins from the "B" Core Spray Pump check valve
1BEV-015,
and SACS Pump check valves 1EGV-019 and 1EGV-013 were magnetic
particle
tested, and no defects were identified.  In each of these three
cases,
disc-to-body contact or disc flutter were observed.  Also, during
early
1991, the "B" RHR pump discharge check valve 1BCV-008 was
disassembled
and visually inspected.  No deficiencies were noted with those
valve
internals at that time.

A review of the expected system flow parameters, valve operating
characteristics, valve cycle history and the recent inspections
of the
Core Spray and SACS check valve's disc pins provides reasonable
assurance
that no disc pin failures are expected to occur in the remaining
systems
in the near term.

For all of the systems involved, initial startup of a pump
typically does
not result in a large initial mass flow, and therefore, low disc
pin
impact loads are expected should disc-to-body contact occur.  For
the
ECCS check valves (Core Spray and RHR), the pumps are started
with no
discharge paths open other than minimum flow pathways.  Since the
minimum
flow lines are upstream of the discharge check valves, this open
path way
will not result in the discharge check valves opening until a
process
flow path is established.  Additional increases in pump flow are
controlled by motor operated valves.  In addition, a Keep Fill
system is
utilized to minimize the initial surge due to pump starts. 

Therefore,
opening of the ECCS check valves is not expected to result in
excessive
impact loads.  The opening of the SACS pump discharge check
valves on
pump start could yield high disc impact loads.  However, no disc
pin
failures have been observed to date based on the inspections of
"C" and
"D" pump

                              Page 3 of 11


LR-N95059
                          ATTACHMENT 1 (cont'd)

discharge check valves that have experienced disc-to-body contact
or disc
flutter.  Anchor-Darling has suggested a "high confidence" no
failure
limit of 1,000 cycles for the type of moderate service the check
valves
normally experience.  A conservative estimate on the number of
cycles
that the Core Spray, SACS and RHR check valves may have seen
during the
first 10 years of operation at Hope Creek was made based on pump
starts. 
Each pump start was assumed to result in impact.  The maximum
number of
impacts estimated was 250 based on "A" and "B" RHR check valves. 
The
number of impacts was estimated based on system normal operation,
surveillance testing and post maintenance testing, and also
includes
additional margin for conservatism.  The effects of pump start
impacts
are considered to bound possible disc flutter.  For each of these
systems, the number of impacts is well below the 1,000 cycle
limit
provided by Anchor-Darling.

Check Valve Failure in the Open Position

This failure mode was evaluated for Hope Creek on the Core Spray,
RHR,
SACS and FPCC systems to determine the impact on system operation
following a design basis accident.  A summary of this evaluation
is
provided below:

Core Spray System - Should a single active failure (i.e.,
unavailability
of Channel A dc source) be considered concurrently with a check
valve
failure in the open position in the remaining loop, both loops of
the
Core Spray system could be inoperable.  The check valve failure
in the
open position will result in a loss of that loop if the
associated pump
is no longer running.  This could result in parallel pump runout
because
of the common header piping configuration.  If a Core Spray
injection
line failure occurred in the remaining loop, both loops could
also be
inoperable.  In both cases, the design of the Emergency Core
Cooling
Systems (ECCS) would ensure that a sufficient combination of ECCS
equipment (i.e., 3 Low Pressure Coolant Injection (LPCI) loops
and the
Automatic Depressurization System (ADS)) would be available in
the event
of a Loss of Coolant Accident (LOCA) even if offsite power was
not
available (See Hope Creek UFSAR Subsection 6.3.1.1.2).  The
sequence of
failures that could result in a loss of both Core Spray loops is
considered highly unlikely.  Therefore, check valve failures in
the open
position would not prevent the ECCSs from mitigating a Design
Basis
Accident (DBA).  The Low Pressure Coolant Injection (LPCI) mode
of RHR
operation in the event of a check valve failure is discussed
below.

The Core Spray check valves are normally closed and open only
upon ECCS
initiation or surveillance testing.  The failure of a

                              Page 4 of 11


LR-N95059
                          ATTACHMENT 1 (cont'd)

Core Spray check valve in the open position would be readily
identified
following performance of surveillance testing due to the failure
of the
Keep Fill system to maintain downstream pressure when the system
is not
operating.  Failure of the valve is only a concern if the pump is
initially started, the check valve sticks open, the pump is
stopped and
cannot be restarted.

RHR - The RHR system is designed with four independent loops
without the
pump discharge piping cross-connected.  A check valve failure in
the open
position will not prevent the loops from performing their
intended design
function.  Upon ECCS initiation, the LPCI mode of RHR operation
will
result in all four RHR pumps starting.  As is the case with Core
Spray, a
single active component failure (i.e. unavailability of Channel A
dc
source) would result in the loss of one LPCI loop.  Three LPCI
loops
would be available to mitigate the event.  If a piping failure
was
assumed in the RHR system instead of the Core Spray system, the
remaining
Core Spray loop would be available as discussed above (See Hope
Creek
UFSAR Subsection 6.3.1.1.2).  Although it could be postulated
that a
combination of RHR and Core Spray failures in conjunction with a
check
valve failure in the open position could result in less ECCSs per
UFSAR
Section 6.3.1.1.2, it is considered highly unlikely based on
engineering
evaluation including Probabilistic Risk Assessment (PRA).

Long term containment cooling is performed using either the "A"
or "B"
RHR loops.  Long term cooling is provided through either the "A"
or "B"
RHR pumps and is initiated after approximately 10 minutes
following ECCS
initiation.  Either pump provides adequate flow to accomplish
this design
function.  Pump flow is not terminated to align the RHR pumps for
long
term cooling.  Vessel makeup is accomplished using either 1 RHR
loop or
Core Spray loop.  A sequence of failures that could result in the
ability
to provide vessel makeup is considered highly unlikely.

The RHR check valves would be normally closed and open only upon
ECCS,
Shutdown Cooling initiation or surveillance testing.  The failure
of a
RHR check valve in the open position would be readily identified
following performance of surveillance testing due to the failure
of the
Keep Fill system to maintain downstream pressure when the system
is not
operating.  Failure of the valve is only a concern if the pump is
initially started, the check valve sticks open, the pump is
stopped and
cannot be restarted.

SACS - The consequences of a failed open SACS pump check valve is
similar
to that of the Core Spray System.  Loss of pump flow may occur in
the
parallel pump if the opposite pump is stopped with

                              Page 5 of 11


LR-N95059
                          ATTACHMENT 1 (cont'd)


its discharge check valve stuck in the open position.  This pump
would
trip resulting in the loss of that SACS loop.  However, this
would result
in automatic swap over to the other SACS loop to provide the
required
cooling.  Only one SACS loop with one pump is required to operate
and
safely shutdown the plant.  A single active failure along with a
postulated piping failure in the redundant train is not
considered
credible per HC UFSAR Section 3.6.1.1.  SACS check valves
associated with
pumps "C" and "D" have been repaired to prevent disc-to-body
contact.

FPCC - The bases for concluding that a failure of the FPCC check
valves
does not constitute a Substantial Safety Hazard in accordance
with
10CFR21 as described in UFSAR Section 9.1.3.

To date, there have been two check valves that have stuck in the
open
position due to disc-to-body contact (FPCC pump discharge check
valve
1ECV-007 in 1989 and Core Spray pump discharge check valve
1BEV-015 in
November, 1994).  Because the failures to date have been
attributed to
deficiencies and casting variations that may reduce clearance
between the
disc and body, it is expected that the failure mode would be
random in
nature.  Multiple failures of check valves in the open position
is
considered highly unlikely during a single event.  Check valve
1ECV-007
was repaired in 1989 to prevent disc-to-body contact.

Therefore, it is concluded that the subject deficiency is not
considered
an immediate operability concern while inspection and repair of
the hinge
arms is ongoing.

III. CORRECTIVE ACTIONS

The overall schedule for completion of valve inspection, and
repair or
parts replacement for the remaining valves is no later than prior
to
startup following Refueling Outage # 7 (Spring, 1997), with
specific
valves presently scheduled to be completed sooner based on
relative risk.

Prior to completion of these corrective actions, the following
actions
will ensure continued valve operability:


- ECCS pump discharge check valves operability will be determined
by
either routine quarterly surveillance tests (which evaluate
system flows
and idle pump status), or by the ability of the ECCS Keep-Fill
Systems to
maintain downstream pressure when the system is not operating.

                              Page 6 of 11


LR-N95059
                          ATTACHMENT 1 (cont'd)

- SACS pump discharge check valves operability will be determined
by
either routine quarterly surveillance tests (which evaluate
system flows
and idle pump status), or by verification of appropriate system
flows
during routine system realignments.

- Although not considered a Substantial Safety Hazard, FPCC pump
discharge check valves operability will be determined by
verification of
appropriate system flows during routine system realignments.

If the above testing methodology identifies a new check valve
failure,
the surveillance and/or verification frequency will be evaluated
to
ensure continued operability.

PSE&G is also considering the development and implementation of a
Design
Change Package (DCP) to install an extended tail stop design to
absorb
the impact during valve opening instead of the butt stop design
presently
installed in the 16 affected valves at Hope Creek.

It is also noted that a review of selected additional hinge arms
in
storage showed either no tail stop or the non-functional older
hinge arm
tail stop.  The hinge arms that contained a small non-functional
tail
stop appear to be part of the older design although not reflected
on the
design drawings.  The hinge arms may be used during valve repair,
and
modified as necessary to ensure proper valve function.

                              Page 7 of 11


                                                       LR-N95059

ENCLOSURE 1 "Figure" omitted.

                              Page 8 of 11


                                                       LR-N95059

ENCLOSURE 1 (cont) "PARTS LIST" omitted.

                              Page 9 of 11


                                                       LR-N95059

ENCLOSURE 2 "SWING CHECK" omitted.

                              Page 10 of 11


LR-N95059

                               ENCLOSURE 3

              LIST OF AFFECTED ANCHOR-DARLING CHECK VALVES

SACS PUMP DISCHARGE CHECK VALVES (20", 150#)

1EGV-010
1EGV-013
1EGV-016
1EGV-019

CORE SPRAY PUMP DISCHARGE CHECK VALVES (12", 300#)

1BEV-013
1BEV-014
1BEV-015
1BEV-016

RHR PUMP DISCHARGE CHECK VALVES (18", 300#)

1BCV-002
1BCV-008
1BCV-099
1BCV-105

FPCC PUMP DISCHARGE CHECK VALVES (6", 150#)

1ECV-007
1ECV-040

FPCC FILTER DEMIN OUTLET CHECK VALVES (8", 150#)

1ECV-015

FPCC FILTER DEMIN OUTLET RETURN TO TORUS CHECK VALVES (6", 150#)

1EEV-007

                              Page 11 of 11


*** END OF DOCUMENT ***

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