IR 05000395/1989019
| ML19325F017 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 10/20/1989 |
| From: | Blake J, Chou R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML19325F016 | List: |
| References | |
| 50-395-89-19, NUDOCS 8911130224 | |
| Download: ML19325F017 (15) | |
Text
w
-
,
...
.
'.,
Sm it g, UNITEo ST ATES
/
'o NUCLEAR REGULATORY COMMIS$10N
y REolON 11
,
.g g
101 MAnlETTA STREET.N.W.
,,
- *
g ATLANTA.oEoRol A 30323
- %g..... p l
'
.
Report No.:
50d95/89-19
Licensee:
South' Carolina Electric & Gas Company Columbia, SC 29218 Docket No.:
50-395 License No.:
NPF-12 Facility Name:
Sumer
'
Inspection Conducted:
Septen'ber 11-5, 1989
/ !I1/If Inspector:
C*
@
Ric ho Date'S gned Approved by:
-
/2 v
/4 24 MI J.
. jrlake, Chief Date Signed i
Ma rfalsandProcessesSection l
E ineering Branch
.
Division of Reactor Safety SUMMARY Scope:
i l
l This special unannounced inspection was conducted in the area of water hammer i
problem in a 4" diameter feedwater, forward-flush line, loop A, during the last startup.
The line is a nonsafety-related system and the Code involved is ANSI Code B31.1..
L
Results:
L In the area inspected, violations or deviations were not identified.
The preliminary investigation for root cause indicated a problem with the valve closing and opening sequences during the startup.
Wrong sequences allowed
,
l water into the 4"$ empty line whict struck the valve to create a water hammer.
All damaged pipe supports were repaired or repisced.
The pipe with apparent damage was examined by Ultrasonic Testing (UT).
The licensee changed the valve operating sequence procedures and successfully completed the restart processes during the weekend of September 16, 1989, without water hamer problems.
!-
l
l 8911130224 891031 PDR ADOCK 05000395
.Q pHU
- -
~:'
..,['
.
(
.
i
..
f.
p.
- .
REPORT DETAILS r
,
U 1.-
Persons Contacted Licensee Employees
- M. A. Barth, Design Engineering Specialist
- M. N. Browne, Systems and Performance Engineering Manager
,.
!
- R. M. Campbeu, Senior Engineer R. Clavy, Design Engineering Manager L
- H. I. Donnelly, Regulatory Interface Senior Engineer
- M. Fowlkes, Associate Manager-Shif t Engineer
- M.. Garrett, Associate Quality Control (QC) Manager D. 'Goldston, Operation Test Unit Supervisor S. Hunt, Quality Systems Man 6ger J. Juvkett, Feedwater System Engineer
- A. R. Koon, Jr., Nuclear Licensing Manager
- G. V. Meyer, Design Engineering D. Moore, Engineering Service General Manager A. Myer, Senior Mechanical Engineer
- K. W. Nettles, Nuclear Safety General Manager
- J. Proper', Associate Quality Assurance (QA) Manager
- J. L. Skolds, Nuclear Plant Operation General Manager
- G. Soult, Operation and Maintenance General Manager
- G. J. Taylor, Operations Manager A. Torres, Nondestructive Examination (NDE) Supervisor
- R. J. Waselvs, Associate Design Engineering Manager Other licensee employees contacted during this inspection included craf tsmen, engineers, operators, mechanics, technicians, and administra-tive personnel.
Other Organizations Gilbert / Commonwealth, Inc.
j
- E. J. Anselmi, Principal Mechanic Engineer l
- A. R. Hoffert, Piping Project Engineer
- D. J. Lengel, Mechanic Project Engineer
,
NRC Resident Inspectors R. Prevatte, Senior Resident Inspector
- L. Modenos, Resident Inspector
- Attended exit interview i
t i
.
.
(
-
.
.,
(
n
?
l 2.
Water Hammer Event Report j
t l
On September 7,1989, the. chemistry department of V. C. Summer notified
'
operations that secondary chemistry was out of specification and it appeared that there may be a condenser tube leak.
Power was reduced and the investigation for cause was started.
The plant was completely shut down because Main Steam Ir.olation Valve (MSIV) A was found to be inoperable.
Approximately 25 condenser tubes were found to have damages.
During the investigatica of problems with MSIV A, it was discovered that a
,
severe water hammer hed occurred in the 4" diameter feedwater, forward flush line for steam generator A.
This system is used during plant
startup to warm up the main feedwater line up to the isolation valve.
The water hammer had crushed an electrical conduit containing wiring for MSIV A.
The water hammer had also damaged 9 pipe supports in the 4" diameter forward flush piping and a support-for a main steam line.
The damage'in the supports included pull out of Hilti anchor bolts, sway strut r
sheared off, rod bent, support members bent, etc.
At two or three -
locations, the piping had a slight deformation and denting.
3.
Inspector Field Walkdown on the Damaged Piping
,
The inspector went to the field to review and assess the piping and support damages created by the water hammer, after a brief by the licensee engineer about the event and damages.
The Isometric Drawing No.
i 04-4461-C-314-081, Sheet 34, Rev. 1, Feedwater Forward Flush-Loop A and the
,
detailed pipe support drawings were used to estimate, evaluate and assess the piping movements, load directions, piping deformations, support
,
damages, conduit damage, main steam line support damage. and other problems.
The licensee took pictures of the damages to help the
-
investigation, evaluations and root cause analysis.
Those pictures were reviewed by the inspector and used to estimate the pipe movements and
.
l other damages.
Listed below is a summary of damages and pipe movements
",
created by water hammer and solutions completed or planned by the
'
licensee.
Most damaged supports had been restored to the original design by repairs or replacement prior to the inspector walkdown.
Loop B for l
Steam Generator 8 and Loop C for Steam Generator C which have a similar
function and probably also went thru the water hammer transient had no
'
damage at all to supports and piping because those two lines had seismic
.
design with the restraints in the axial direction.
N
'
l l
l 1.
l l
i l
pqy
-
~
N
,
[i,s
.-.
{'
' N,
.,,.f
'
(b4 '
'
e,
_
f
,
,
A :,.
.
.a
- -
I
.
Table 1
J Piping and Support Damages b,,
Item No'.
Pipe Support / Pipe Location Damage / Solution Description.
- T.T 1.
Support FWH-425 Damage:
Rigid Rod Strut was
-
l' '
bent about l'.
c h:
Solution:
Straighten the
bent rod.'
<
.
.
y
,
2.
Support FWH-426 Damage:
(1) Two nuts on
<
D top Hilti bolts were loose due g
to pullout.
'
o (2) The paddle L
plate on the rigid sway i
strut was bent.
Solution: (1) Retorque nuts
-
to satisfy the.
t torque requirement.
(2) Replace paddle plate.
.
.
3.
Support FWH-5000 Damage:
(1) Two nuts on top Hilti bolts wero loose'due
,.
to pullout.
,
-
(2) There was a slight damage on pipe at t
two sides of
'
support.
i Solution:
(1),Retorque nuts i
,
to satisfy
!
the torque i
requirement.
I l
h
!
l i
i t
I
!
.;4..,.
-_
.
.
.
-
_ - -
. _...
--
J
-
q-
- - - - -
- ~ ~ ~ ~ -
-
,,;
,
,
,m m
- ,-
'" $
, ' '
'
ph.S j :
_
'it
-
.
.>
--
y,..
O:
i i '![
!
g j.
\\
.
!
p;' "-
Item No.
Pipe Support / Pipe Location Damage / Solution Description l
[,e (cont'd)
,
,
--
'3 (2) No cracks, no
-
,
'
~
. pipe wal.1
b
,
n 4.-
thickness
'
['
reduction, or other-indica-tions were.
,
'
,
g~y found per l
L Ultrasonic t
h; " '
inspection
[
(UT) report
,
-
!
VCSU-552 and F:.,
553.
i p
i
"
'4.
Support MSH-300 Damage:
(1) 3"$ Rigid
.i C
J (Main Steam'Line)
Strut tube
!
F
-
was bent about 2".
!
- i 3-(2) There was
-
'
slight i
damage on 4"$
!
pipe at this
-
location.
'
i
!
L Solution: (1) Replace 3"$
'.
rigid strut
tube with
>
4"$ tube.
[
(2) No cracks..no u
!<
pipe wall i
thickness
- -
reduction, or u
other indica-tions were found per UT report
,
VCSU-552
'-
and 553.
l
.+
5.
Support FWH-427 Damage:
Rod was bent.
l
. > -
l Solution:
Replace Rod.
!
6.
Support FWH-428 Damage:
(1)
Angle had
-'
crack l
near weld connected l
to channel.
!
,
c
.,
I f
mr w.
,
,
i:
-
.. -
t
'.. g
.;
.
,
.;,:'y'
l L
'
,
c
.
.t
..
,
,
,'
.
~
.h
,
,.
Damage / Solution Description j
. Item No.
Pipe Support / Pipe Location'
'
'
,
-(cont'd)
i
,
g, (2) Angle and j
,
'
strap were
'
bent.~
b;
!
'
,
(3) There was a 5"-
'
.
movement to
-,
[
north, based
.!
O w
on the broken
insulation.-
(
q L.,
Solution: (1) Replace angle
";
!;
and strap..
.
t.
I h
(2) Add a new stiffener
,
,
.
l plate to
[
reinforce
!-
channel.
,
.
t
'
(3) No cracks, no-l
,-
L pipe wall
.I
[
thickness
!
,
L reduction or
'
.other indica-i n
tions were l
found per UT
.
report-t
VCSU-552 and 553.-
.
7.
Support FWH-429~
Damage:
(1).No damages-I were found
!
at support and i
piping.
!
r (2) Pipe movements
[
were found
!
.
greater than 4" in both
- -
directions
!
along the
!
y'.
pipe line based on the broken insulation.
Solution:
Not required.
,
!
i
<
%
y
.,
-
,
-. - -
- -, - -.
--
.,
,..,,
,,,. -.-
. -,
,,o
_s
.. -.
.\\ (,
--
-
-
~
-
-
-
-
gy.
?
i34 ' A.'
d '-
'
,
.
wi
.
,
!
.e
,
~ m.s
'
,
'
i
,
_m s.
-
. 6-.
l l
'
q
.
'
. Item'No.
Pipe Support / Pipe location
. Damage / Solution Description.
. {
.
,.'
(cont'WJ
.
'
'
8.
- Support FWH-430.
Damage:
(1) Rigid strut
was sheared off-i
,
at rod on the
-.O paddle plate
'
,
which was above pipe
'
' clamps.-
t (2) Pipe crushed;
!
?.
the instrumen--
!
' '
tation conduit
, !
' '
.(contains~
. *
main steam-j valve testing i
wire) and I
conduit was
. flat'at the i
. crushed face, f
341
'
~
(3) Pipe movements were found p
approximately N
4 1/2" in both
-
-
-directions along the pipe
[
line based i
on the broken.
insulation.
,
(4) Fire barrier nearby was j
damaged.
-
Solution: (1) Replace a new
,
rigid strut.
.
,a k-t
,'
t
,
f
e
, - - -
r.=,
a...
,
-- -
- - - -
,
s
,
,.,. -,-
e
,,, -, -- l
b:
x.,
a
.
p..
<
%, :..,r. j,,
-
.
t
..
<
,
.h,.
-q[ig
!
+
V y 3;-
l
.,.
ym-
..
,
}c/-
..
.
!
fa
.
~
1, ' <
Item No.
. Pipe Support / Pipe location D_amage/ Solution Description
- E
'
'(cont'd)
'
,
(2) Repair _ conduit
.;
'
,
,
- y and circuit
.;"
'
V
.. "
MSW185A and l
'
'
'
-
-
add a splice.
'
box and.
i
,
support per._
i e
Technical Work
>
u.
3.'
Record (TWR)
!
,
Serial No.
.5381 for.
-'
-
disposition #2
on Project-
.
Title NCN 3440.-
i
'
(3) Rework fire
,
J'
barrier
!
,
per;the above
.:
same-TWR.
l
(4) No cracks,'no f
'
. pipe wall
!
thickness-
.
- reduction or
'
t other indica-l tions were
'
found per UT report VSCV-552 and 553.
,
b i.
9.
Support FWH-431
. Damage:
(1). No damages
L were found on t
support and pipe.
i t
(2) Fire barrier i
,..
for penetra-I tion which
,
is next to support L
was broken
,
off.
,
i l.
I
' '
<
.
'y,-
w
g w.
w-tp-
---w-nr g-
-s
,e
+-
,,-
p w
wr-
{ a:yg.
~^
'
,j w.y
,
.
.
_
\\ '
7,'.
'
h s
,32 e
.
- '
,g
'
,
i,.
..s
.. ;.-
i
,
,
-
e
.
.-
>
n
,3 1 _. Item No._ Pipe Support / Pipe' Location-Damace/ Solution Description
.
.
(<)
L % nt'd)
3-
-
,
(3)
The Slight _
o
[..
'
'
pipe
'
"
.
i.
. c movements were
-
found' based on-
' ' '
[
the damages
'
-
'
and restraint
.of support
,
L..
FWH-432 and
the fire
!
barrier
.;
broken off.
- Solution:
Repair. fire'
f
- '
. barrier.
{
,
'
- 10.
Support FWH-432 Damage:
(1)~ All nuts on
'
.;
Hilti anchor'.
- '
'
bolts were-F pulled out.
,
[E
^
The nuts on-
.
two bolts
!
..
at North were
!
pulled out'1".
L The nuts on
[L.;.
two bolts
!
-
at South were
pulled out
!
3/16".'
!
t '
(2)
Angle was bent l
about 7 to.
.!
'
West and K
' deformed.
(3)
Pipe strap was bent.
('
(4)
Pipe movements L
were found
->
5" to East
-
and 4" to West i.
along the pipe o
i L
line based i
on the broken
'
li insul.ition.
l-i 1.(
I,-
i (
h.
I t
..,
...,
.... -........
.. - - -
-. -..
. _ -.
,
, i
- - - - -
._
3,
,
,'
d
'
<a,
'
y;. ~
-
(
e
'
x y
l '-
j i-
t.r
,
i
Item No.'
Pipe Support / Pipe Location'
Damace/ Solution Description
. :
L
.
(cont'd)
[?..
,
.
.
.,
"
Solution: (1) 'Three nuts (or.
'
'
bolts) can be
<
t-retorqued to-If the torque-(L requirement.
One bolt will
[
.be replaced
'
with aL
[
longer' length of bolt from
[.-
9" to'12"
"
(2) Baseplate,.
c.
pipe strap, L
and angle
['
will be
replaced.
I (3) UT will be
'
performed on
>
the pipe e
welds around
- .
support to-check crack and the
[
thickness of pipe wall.
,
11.
Support FWH-433 Damage:
(1) No damages to support and pipe were found.
'
(2) Pipe movements were found
~4" to East l
and 5" to West i
"
,
along the pipe
line based i
on the broken
!
insulation.
l
'
'
i Solution:
(1) Not required.
,
12.
Support FWH-434 Damage:
(1) The nut on the I
T Hilti anchor bolt at i
'
South-West Corner was pulled out.
l t
,
i.
-
.i-
.
CI
,
p. '
,
-
,
,
'
fl
"d
_
'
,
J. %
.j
,u i
hn
)
-
,
,
h
. Item No.
Pipe Support / Pipe Location
' Damage / Solution Description'
I L
(cont'd),
.,
(2) An apparent
!
crack was
!
found on weld i
^
'
connecting an i
angle to the
baseplate.
'!
t
.(3) Pipe movements
were found
!
4" to East
<
i and 5" to West l
'"
.along the pipe i
P line based on
the broken j
l
,
'
s insulation.
Solution: (1) >The nut was d
!L-retorqued to.
the require-ment.
,
(2).The weld was ground below
-
..
paint and i
"
no crack e
indications j
[q were found-
,
,
(3) Pipe around
!
this support
}
will be
'
!
13.
Support FWH-435 Damage:
No damages to
.
support and L
pipe were
'
l'
found.
'
<
'
,
,
i-l'
,@
_
_
.-... _ _.
-.. _. _
,-
,_
_
.
- __,
--
mp
.
.-
-
,
,
._
,
c.,y g.-
,
,
,
! ';
'
(
i r,
.[
,..
(i
~+
.
.
.
,,. i ?i.
-
s.g
- _
Wi -
'
11-i
'
j g-
,a
,
>
%
j
,
.
Item No.
Pipe' Support / Pipe Location.
Damage / Solution Description I
4-(;'l 7,
( cont '.d)'
.
.
l
~
Solution: -(1). A visual.
i
'
, inspection
l
was performed
'
- ,
for pipe roundness and'
r
[
. damages since
-
,
'
the are'a was L
subjected to a
? 5 big bending
~i
'
...
' moment and.
s
'no apparent ~
..
L damage..was j
,
-
noted.1
.t e
q e w (2) Pipe welds
.
betweent
,
' Support
..
H-FWH-434 and'
,
'
FWH-435 will.
>
L be examined
'
<
-
,
l'
.
.14.
Support FWN-436
' Damage:
No. damages to support and
!
"
'
pipe were.
.
..,
'
found.
.
Solution:
Not. required.
15.
Anchor'FWH-437.
. Damage:
No damages to
anchor and-
.:
' pipe'were s
'
found.-
J Solut1oa:
Not required.
[
'
4.
Review of Operating Procedures and Valve Operating Processes During Event
o
.
b The following operating procedures were reviewed to understand the j
!'
operating processes for restart and assess the event which might be caused
,
l^
by.the improper operation:
i
,
a.
SOP-210, Rev. 10 - Section A, Feedwater System Header Warming of Chapter III Normal Operations.
j L
b.
GOP-4, Rev. 8 - Chapter IV, Instructions c
I
'
,b'H
'l
-
t i
s
,
,
.., - -, -
p
]
g L.
.
?
,
,
,
G
!
-
-
<
r c.
File No. 20.6600 or C GSS-17635, Exhibit II or REE 21159, Feedwater
^
-
Cleanup Recirculation Line, dated November 7, 1986 - Disposition For REE 21159.
d.
Design Basis Document for Feedwater System Rev 4 All the above procedures allowed tH valve XVG 1681-FW, Main
,
Feedwater Header Recirculation to Cownser Isolation Valve, to be
'
used for the flow thru the foward flush valve XVG-1689-FW or the recirulcation valve XVG-1676-FW for forward flush or recirculation
. during a t,tartup.
But both of procedures, references C and D above, require that the deaerator start-up drain valve IFV-3235-FW,
.
"
for draining the water from the deaerator to the condenser, and valve
'
-
XVG-1677-FV, for normal forward flush back to deaerator, are to be closed. Therefore, valve XVG-1681 and valve XVG-1677 cannot be opened at the same time.
!
During a meeting with. the licensee operating supervisor, system engineer, design engineering supervisor, licensing engineer, and engineers from Gilbert / Commonwealth, Inc., a preliminary valve operating sequence was presented.
Valve XVG-1681-FW and valve XVG-1677-FW were opened at the same time during a period and the
,
water level at the deaerator dropped rapidly.
Valve XVG-1681-FW and valve XVG-1677-FW were opened and closed several times which might or might not be at the same time.
During this meeting, the licensee was
-
still performing the root cause investigation and impact evaluation since some data and opening and closing sequences of some valves l
needed to be verified and compared with the reports from operating
.
personnel.
5.
Licensee Actions After Event The licensee took the appropriate action to shut the plant down and investigate the root cause of the water hammer after declaring the MSIV A to be inoperable.
The licensee estimated that it would take a week to repair or replace all the damaged components and complete the preliminary investigation of root cause.
During the inspector's walkdown review of damages, it was noted that the licensee had completed the majority of repair or replacements of supports and inspection of piping by UT as stated in Table 1 of Paragraph 3.
6.
Data and Document Review The following data or documents were partially reviewed for their adequacy:
a.
Piping Stress Calculation No. FW-33, Rev. ID.
b.
Pipe Support Calculation No. FWH-435, Rev. O.
c.
Ultrasonic Inspection Reports VCSU-552, 553, and 554.
i
,_
.
_
__ _ --
,
oa
.
,
i
.
f p
l I
[
.
!.
d-QC Inspection Reports for Support Hos. FWH 425, 426, 427, 428, 429, t
430, 431, and 434.
'
e.
QC Inspection Reports for Hilti Bolts for Support No. 426, 427, 430, 434, and 5000.
F i
f.
Nonconformance Notice (NCN) No. 3440 and Disposition No. I to 6.
i
'
The piping stress calculatlons were based on American Society of Mechanical Engineers (ASME) Code, Class 2,
because the system combined the safety related portions from the 18"$ feedwater line o
to the forward flush isolation valve XVG-1689A, and the nonsafety-related portion from valve XVG-1680A to the 8"4 feedwater line.
All
'
the supports except the anchor on the nonsafety-related portion, used the deadweight loads and the thermal loads from the stress analysis; even the whole line was analyzed and printed out with the seismic loads.
All the documents reviewed were considered adequate.
7.
Preliminary Investigation Ret, ult of Root cause
'
On September 15, 1989, the licensee provided the inspector with a copy of the Executive Summary of feedwater System Forward Flushing Line Transient.
,
The summary stated that root cause of this water hammer was that the 4"$
'
flushing line was empty of water and connected to the 1 psia of the condenser thru the opened valve XVG 1681-FW for about two hours.
When valve XVG-1677-FW was opened, the water from the deaerator line (at 50 psia) rushed back to fill the 4"$ flushing line and. struck valve XVG-1689A generating a water
,
hammer.
The sequences are ai follows:
During the normal feedwater systems heatup, the feedwater flush
-
'
system was aligned to allow water through valve XVG-1689 A, B, and C-FW and valve XVG-1677-FW end back to the deaerator.
During this heatup, the system was realigned to an alternate path by
-
i openin0 valve XVG-1681-FW to the condenser and then closing valve
"
XVG-1677-FW to the deaerator due to the deaerator water level increasing and the failure to open valve IFV-3235 to adjust the deaerator water level, t
Af ter the forward flush was completed and at 2 to 3 percent power,
-
valves IFV-3235, XVG-1677,1676 and 1689 A, B, and C-FW were closed, valve XVG-1681-FW remained open.
P
,
Due to valve XVG-1861-FW being opened and the other valves closed,
-
the 4"$ forward flush line was connected to the condenser thru
,
opened valve XVG-1681-FW.
Because the condenser was at 1 psia, the line became empty of water in some areas and filled with steam and steam pockets at the higher elevation of the lin.
.
..
o t
.
r
,
The above situation was lef t for about 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> before an operator i
-
placed the system in the normal operating setup by first closing valve XVG-1681-TW and then opening valve XVG-1677 fW.
Af ter opening Valve XVG-1677-fW, a column of water with 50 psia and
-
about 40 feet elevation difference, rushed down to the 4"$ empty line.
The water passed thru 8"$ piping to forward Flush Loops A, B, and C.
-
When the water reached the closed valve XVG-1689A-fW the momentum of
-
the water mass caused a pressure spike at the valve.
A pressure wave then traveled back through the water in the Loop A forward flush line.
This was the water hammer.
The damage was limited to the supports and piping of Loop A.
A
-
similar but smaller transient probably occurred in loops B and C, but the transient loads caused no damage because the piping had axial restraints based on the seismic design.
8.
Conclusion The cause of water hammer was the wrong valve opening and closing sequences and duration of the opening of valve XVG-1681-FW.
The
,
licensee's corrective actions to prevent future occurrence of similar transients in the system will consist of changing operating procedures to ensure that the system will not be voided during any plant operation cycle.
9.
Exit Interview The inspection scope and results were summarized on September 15, 1989, with those persons indicated in paragraph 3.
The inspector described the areas inspected and discussed in detail the inspection.
Proprietary information is not contained in this report.
Dissenting comments wer2 not received from the licensee.
,
?