ML19345C174
| ML19345C174 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 10/15/1980 |
| From: | COMMONWEALTH EDISON CO. |
| To: | |
| Shared Package | |
| ML19345C167 | List: |
| References | |
| NUDOCS 8012040068 | |
| Download: ML19345C174 (12) | |
Text
.-
f}
i 0
1 Zion Station Units 1 and 2 NRC Docket Nos. 50-295 and 50-304 Results of Unit 2 Steam Generator Snubber-Testing at New Hampshire Testing Laboratory (NHTL), May, 1980 B
=
8
,../
'4
.r.'..-
i l:
B012040 %
i I.
Introduction A.
Background
As ir,1cated in the January 17, 1980, letter from J. G.
Keppler to C. Reed, Commonwealth Edison committed to performing functional testing of the Unit 2 12-inch Bergen-Paterson Steam Generator Snubbers during the 1980 Unit 2 refueling outage.
Prior to the refueling outage, Sargent & Lundy Engineers developed recommended testing and acceptance criteria which Commonwealth Edison incorporated into a testing procedure.
This procecure was also revie.w'ed and commented on by the NRC staff prior to its implementation.
Testing of the snubbers was performed at New Hampshire Testing Laboratory (NHTL), subsidiary of Bergen-Paterson Pipe Support Corporation, Laconia, New. Hampshire.
B.
Objectives The objectives of the proposed testing program were to I
demonstrate operability of two randomly-selected snubbers in each of the following conditions:
4 1..
As-found; E
2.
As-modified to cure a leakage problem caused by galling of the piston rod against the snuboer gland; and 4
3.
Under accident-environmental conditions, one I,
as-found and one as-modified.
9 II.
Test Results A.
Procedure Changes at Test Facility
[
During the testing numerous changes were required to the Zion Nuclear Station Steam Generator Snubber Testing Procedure which was Used during all functional tests.
These changes are described below.
1.
Sideload applied to the snubbers was held constant at
~
+450 lbf in lieu of a varying sideload due to fixturing difficulties.
Sideload had a negligible effect on snubber frictional drag.
2.
Snubber test piping lengths were modified slightly to accommodate the autoclave used for accident-environmental testing.
Functionally, these changes have no ef fect on snubber performance.
3.
Snuboer axial velocity was recordeo; however, indication was too erratic due to Linear Velocity Displacement Transducer (LVDT) sensitivity to be of any value. Average velocities for lockup.and bleedrate were calculated from displacement vs. time data.
t
4.
Functional testing was performed with and without sideload at the request of the NRC, to observe any
_significant effects.
No significant differences in drag were observed.
5.
Bleedrate vs. load curves were unobtainable due to the fact that. load increase after lockup was performed manually.
6.
Additional testing was performed on all Unit 2 valve blocks after bleed compensator springs were. replaced with springs having higher spring rates.
Two valve blocks were flow tested statically, and two were functionally tested using a modified snubber.
8.
Testing Summary Four randomly selected snubbers from Zion Unit 2 were tested--two in as-found and two in as-modified condition.
(It should be noted that none of the sixteen Unit 2 snubbers exhibited the degree of galling / scoring that was observed on the five Unit I snuobers examined and repaired during the last Unit I refueling outage.)
During the testing, frictional drag was observed to be less than 5 KIPS in all cases.
In addition, the effects of a simulated seismic event (transverse sideloading) were determined to be negligible.
Specific testing results are addressed below.
Tables 1 and 2 illustrate the testing results at normal operating temperatures for four snubbers, two each in the as-found and as-mooifiea condition.
The following observations were made from these tests:
1.
The snubbers 'aoved freely with minimum frictional drag
(< 5 KIPS);
2.
No observable leakage was evident; and 3.
Bleedrates were somewhat low, particularly in the as-modified condition (Table 2).
Tables 3 and 4 illustrate the testing results for the accident-environmental condition for two snubbers, one each in the as-found and as-modified condition.
The following observations were made from those tests:
1.
The as-found snubbers' (Table 3) lockup velocities and bleedrates were consistent and generally within the test acceptance criteria'at both normal operating and accident environmental temperatures.
Elevated temperatures hac negligiole effect on oleedrate due to the bleed port compensator action.
2.
The as-modified snubbers' (Table 4-) lockup velocities at both normal operating and accident-environmental temperatures were consistent and within the test acceptance criteria.
However, during this test an inconsistency in bleedrate velocity was noted.
At about 30 seconds into each test run, the average bleedrate velocity dramatically changed.
Thus, as indicated in Table 4, the average bleedrates for the first 30 seconds and for greater than 30 seconds were recorded.
Although the initial bleedrates met the test acceptance criteria, the bleedrates greater than 30 seconds did not.
The problem, as discussed below, was attributed to the valve block bleed port pressure compensator springs.
Again, elevated temperatures had negligible effect on oleedrate.
3.
No observed leakage was evident throughout the testing
~
other than fluid expanding from the reservoir during the extended periods at elevated temperatures.
C.
Resolution of Low Bleedrate Prob'em m
4 After it was noted that the bleedrates were consistently
]
low for the snubber tested in the as-modified conditions
!j (Tables 2 and 4), an investigation centering on the valve
- j blocks was initiated.
This investigation revealed that the spring rates of the installed valve block bleed port e
i pressure compensator springs were less than that required to meet the test criteria.
All Unit 2 valve blocks were then modified with new springs having higher spring rates.
Unit 1 was also shutdown for the same modification.
The modified Unit 2 valve blocks were then satisfactorily tested--two functionally and two statically.
Table 5 illustrates the testing results for Valve Blocks A and B for a snubber in the as-modified condition.
All bleedrates and lockups met the test acceptance criteria.
In addition, Valve Blocks C and D witn new compensator springs were statically tested with a pump, i.e.,
without snubbers.
Thus, in this test, compression and tension velocities were meaningless.
Instead, volumetric leakage versus time was measured at both ports of the valve block and these values were converted to equivalent bleedrate velocities.
The results of this testing are shown in Table 6 with the test acceptance criteria being met in all cases.
. /...
III. Conclusions A.
General The objectives of the Zion Unit 2 Steam Generator Snubber Testing Program were accomplished, i.e.,
the operability of
=a two randomly-selected snubbers in each of the following conditions was demonstrated:
1.
As-found; 2.
As-modified; and 3.
Under accident-environmental conditions, one as-found and one as-modified.
n In addition, simulation of earthquake loa' ding by application of a constant - sloeload had negligible ef fect on drag and functional testing results.
B.
Specific The snubbers tested in the as-found condition performed satisfactorily as indicated in Table 1 ano as discussed in the Testing Summary'Section.
The snubbers tested in the as-modified condition initially i
did not meet the bleedrate velocity test acceptance criteria as indicated in Table 2.
However, with the addition of new pressure compensator springs to the valve s
blocks, the snuobers satisfactorily met the test acceptance criteria as shown in Table 5.
e The snubbers tested under the accident-environmental 3
i conditions-with saturated steam at approximately 2710F
[
performed satisfactorily as inoicated in Tables 3 ano 4 No increase is lockup velocity or bleedrate was observed at m
elevated temperatures.
This is attributed in part to tne action of the bleed port pressure compensator which is designed to maintain a constant 50 psi e p.
Although the as-modified snubber did not meet the test acceptance criteria for bleedrate beyond 30 seconds as shown in Taole 4,
this was attributed to the low spring rate of the valve block pressure compensator springs and not the snubber.
As discussed in the previous section, a problem with the valve block pressure compensator springs was discovered (low bleedrates due to low spring rate) and rectified with the addition of new springs having higher spring rates.
This modification was made to all eight Zion valve blocks, four on Unit 1 and four on Unit 2.
As previously discussed, the four Unit 2 modified valve blocks were theri tested--two functionally and two statically.
All the bleedrates satisfactori.ly met the test acceptance criteria in these tests as shown in Tables 5 and 6.
i
5--
IV. ' Recommendations Based on the results of the Zion Unit 2 Steam Generator Snubber Testing Program, Commonwealth Edison has concluded that the snubbers successfully completed the testing program, i.e.,
the operability.of the snubbers was demonstrated in all conditions.
As a result, all modifications and repairs performed on the Unit 2 snubbers should be completed on the Unit 1 snubbers during the next refueling outage.
In addition, during the Unit 1 refueling outage, one of the five snubbers previously modified and repaired will be inspected to ensure the ef fectiveness of the modifications.
Following completion of the modifications to all the Zion steam generator snuccers, future inspections, surveillances, and testing will be accomplished per the Zion Station Technical Specifications.
l l
I i
i k
8 9
m
e y
t 5
4 t
a i
r 3
3 2
2 9
c d
1 0
1 2
2 o
e l) e 0
0 0
0 0
e
. l Vn B i
nm o/
i n si s(
e p
r u
4 3
5 6
p k
2 2
3 5
6 m
c o
o 3
2 3
6 1
1 C
L ro f
e 6
9 t
y a
3 0
0 0
0 s
t r
1 2
1 2
3 t
l i
d c
e 0
0 0
0 0
us o) e e
l
. l Rn en B o
Vi g
m i
n n/
t i
i on t
d ii 1
s s( p no n
u 5
9 8
5 2
e e
T e
k 5
6 2
1 8
C l
T c
b r
o 3
4 3
6 6
d a
e L
n T
b u
b o
u F n
S s
A 2
d)ao s
t on s
l/
e o
o e
o i
n es Y
N N
Y N
.n U
d e ni y
im i
n S(
m/
o
/n i
Z 5
5 ni 5
5 5
0 0
i p) 0 0
0 1
1 6
mF 1
1 1
0 eO 5
5 0
T(
5 5
5 9
9 8
2 -
9 9
9 6
1 41 n.
uo 1
2 3
1 2
a 00 i
RN re t
yy i
tt r
ii e
C cc ek oo vc e
ll l o C
c ee al A
n VV VB a
t pe p
ut e
ka c
cr c
od r
A Le e
e b
t l
1 b
0 2
s B
u.
2 e
no T
(11 lll 2dll[
1 llll I
-4
,~e Table 2 Zion Unit 2 Snubber Testing Results for As-Modified Condition Tension Velocity
. Compression Velocity (Snubber Valve Run Temp.
Sideload (in/ min.)
(in/ min.)
lNo.
Block No.
(DF)
(yes/no)
Lockup Bleedrate Lockup Bleedrate l
l l
24 8
1 95-105 Yes 3.92 0.017 3.01 0.024 2
95-105 No 3.32 0.022 3.03 0.062 23 C
('
1 95-105 No 3.24 0.006 3.51 0.0 2
95-105 No 5.12 0.003 6.58 0.0 Test Acceptance Criteria:
Lockup Velocity:
0.4 - 28.0 in/ min.
Bleedrate Velocity:
0.116 - 0.6 in/ min.
e 4
6
1 l
Table 3 Zion Unit 2 Snubber Testing Results for Accident / Environmental As-Found Condition y
Tensi an Velocity Compression Velocie.
Snubber Valve Run Temp.
Sideload
.'in/ min.)
(in/ min.)
No.
Block No.
(OF)
(yes/no)
Lockup Bleedrate Lockup Bleedrate 21 C
1 95-105 Yes 5.98
+
+
+
2, 230 5.04 0.38
+
+
3 210 6.02 0.36
+
+
4 230-271 6.73 0.28
+
+
5 271 6.69 0.138 5.76 0.028 6
271
+
+
3.67 0.21 7
261 4.09 0.10 2.12 0.18 8
271
+
+
3.64 0.17 9
271*
3.95 0.30 3.96 0.26 10 95-105 U
3.64 0.27 2.88 0.24
+ Data Not Obtained
- Data taken after 10,000 second hold Test Acceptance Criteria:
Lockup Velocity:
0.4 - 28.0 in/ min.
Bleedrate Velocity:
0.116 - 0.6 in/ min.
Table 4 Zion Unit 2 Snubber Testing Results for Accident / Environmental As-Modified Condition Tension Velocity Compression Velocity (in/ min.)
(in/ min.)
Snubber Valve Run Temp.
Sideload Lockup Bleedrate Lockup Bleedrate No.
Block No.
(DF)
(Yes/No)
<30 sec
>30 sec
<30 sec
>30 sec 23 C
1 271 Yes 3.58 0.26 0.002 4.90 0.30 0.001 2
238-250 8.3
+
+
3.30 0.57 0.13
+
+
+
3.39 0.33 0.05 3
238-250 4
c5-105 3.43 0.13 0.13 3.43 0.0 0.0 5
238-250 5.80 0.29 0.0 4.76 0.50 0.02 6
238-250
+
+
+
8.48 0.40 0.06
+ Data not obtained Test Acceptance Criteria:
Lockup Velocity:
0.4 - 28.0 in/ min.
Bleedrate Velocity:
0.116 - 0.6 in/ min.
W 4
m Table 5 Zion Unit 2 Snubber Testing Results for As-Modified Condition With New Compensator Springs Tension Velocity Compression Velocity s
Snubber Valve Run Temp.
Sideload fin / min.)
(in/ min.)
No.
Block No.
(DF)
(yes/no)
Lockup Bleedrate Lockup Bleedrate 21 A
1 95-105 Yes 3.29 0.25 3.54 0.13 2
3.69 0.20 3.41 0.18 3
9 3.56 0.18 3.35 0.18 21 B
1 95-105 Yes 4.40 0.19 2.96 0.26 2
4.01 0.17 3.13 0.21 3
v 3.62 0.18 3.23 0.24 Test Acceptance Criteria:
Lockup Velocity:
0.4 - 28.0 in/ min.
Bleedrate Velocity:
0.116 - 0.6 in/ min.
O
Table 6 Zion Unit 2 Static Testing Results for Valve Blocks With New Compensator Springs Equivalent Bleedrates Hydraulic (in/ min.)
Valve Temp.
Pressure Run 1 Run 2 Block (OF)
(psig)
Port 1 Port 2 Port 1 Port 2 C
70 2000 0.18 0.23 0.21 0.24 3000
+
0.26 0.21 0.25 4000 0.20 0.26 0.23 0.26 5000 0.21 0.26 0.23 0.27 6000 0.23 0.28 0.24 0.27 7000 0.23 0.28 0.25 0.27 8000 0.25 0.28 0.26 0.28 8500
+
0.27
+
0.27 D
70 2000 0.22 0.20 0.22 0.21 3000 0.23 0.22 0.23 0.23 4000 0.23 0.23 0.24 0.22 5000 0.25 0.23 0.24 0.23 6000 0.25 0.24 0.25 0.23 7000 0.26 0.24 0.25 0.24 8000 0.25 0.25 0.26 0.24 8500 0.26 0.24 0.27 0.24
+ Data Not Obtained Test Acceptance Criteria:
Bleedrate Velocity:
0.116 - 0.6 in/ min.
.~