ML20126K688
| ML20126K688 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 12/30/1992 |
| From: | OMAHA PUBLIC POWER DISTRICT |
| To: | |
| Shared Package | |
| ML20126K685 | List: |
| References | |
| NUDOCS 9301070228 | |
| Download: ML20126K688 (27) | |
Text
_ _ _ _ _ _ _ _ _ _
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4 1992 THERMAL SHIELD INSPECTION AND REPAIR OMAllA PUBLIC POWER DISTRICT FORT Call 10VN STATION
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TABLE OF CONTENTS Page Number 1.0 Definitions.............................
1 2.0 Introduction 2
2.1 Abstract 2
2.2 General Description......................
2
2.3 Background
3 1
I 3.0 Internals Vibration Monitoring and Indications of Pin Degradation..
4 3.1 Thermal Shield Inspection Commitment 4
3.2 Internals Vibration Monitoring Data Reduction Prior to End of Cycle 13 Inspection 5
4,0 Description of the Repair Approach 5
5.0 As-found Inspection Results.....................
5 5.1 Vi s u al I n s pect i on.......................
5 5.2 Preload Inspection 6
6.0 Description of Repair Recommendation 6
7.0 Repair Results 8
i 7.1 Pin Removal..........................
8 l
7.2 Repai r Prol oad s........................ 8 7.3 Repair Evaluation.......................
9 List of Tables and figures
....................10 References
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1.0 DEFINITIONS A control channel excore detector (Currently A Safety Ac Channel) l Bc B control channel excore detector (Currently D Safety Channel)
B safety channel excore detector Bs C safety channel excore detector Cs I
PSD Power-spectral density, a measure of signal power within discrete frequency bands over specified frequency ranges i
In-phase data, used in C05 20 excore detector 0'
Phase information 180' Phase Out of-phase data, used in C0S 30 excore detector information i.
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!NTRODUCTION 2.1 Abstract During the Spring 1992 (End of Cycle 13) Refueling Outage an inspection and repair of the Reactor Vessel Thermal Shield system was performed at the Omaha Public Power District (0 PPD) fort Calhoun Station. A complete visual inspection of the support lugs and positioning pins was first performed followed by an "as-found"preloadmeasurementof11ofthe16lowerpositioningpins.
Based on analytical evaluations of the *as-found" preload state of the positioning pins, seven (7) d replaced with(4) upper existing lower and four positioning pins were removed an new positioning pins and mechanical locknuts.
The new positioning pins were preloaded to establish a long term coupled state between the thermal shield (TS) and core support barrel (CSB).
2.2 General Description The TS is a 3" thick, 304 stainless steel cylindrical structure with an inside diameter of 127" and a height of 164" (by eigttFigure 1).
The thermal shield is vertically supported at the top equally spaced support lugs welded to the outer periphery of the CSB.
The TS lug support pins were fitted during assembly to position the TS on the sup ort lugs.
The main function of tie lugs is to support the wei ht of the TS.
The TS is positioned and constrained radially by a otal of twenty-four (24 positior ing Light of the positioning pins are located be) low the f.upport pins.
lugs and the remaining positioning pins are located approxinately 10 from the bottom of the TS. At the lower positioning pin locations, stellite wear surfaces are welded to the CSB as bearing surfaces for the positioning pins.
There is no stellite on the core support barrel at the top pin locations.
The positioning pins are threaded into the TS and were originally torqued to 250 ft-lbs (approximately 8,000 - 10,000 lbs preload) against the CSB, thus coupling the TS and CSB.
In the original configuration, locking collars were threaded on the positioning pins and torqued against the TS, thereby preloading the locking collars and positioning pins to the TS.
The locking collars were then lockwelded to the positioning pins and the TS to prevent rotation and provide a means of capture (Figure 2). The replacement positioning pins and locking collars are installed and preloaded in a similar manner.
However, the replacement locking collars are mechanically crimped to the positioning pins and TS to prevent rotation and provide a means of capture (figure 3).
Page 2
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2.3 Background
The first ten year inservice inspection (ISI) of the reactor vessel and its internals was conducted at fort Calhoun Station during late 1982 and early 1983.
This inspection revealed that all accessible )ositioning pins, locking collars and lock welds were intact wit 1 no evidence of abnormal wear. Aten-year inservice inspection was also carried out in 1982 on the reactor vessel and internals at Maine Yankee.- This ins)ection revealed that three positioning pins were missing from t)eir original positions.
Similar inspections performed at St. Lucie Unit 1 in early 1983 revealed extensive damage to the thermal shield and its su) port structure.
The St. Lucie I thermal shield was su>sequently removed due to this damage, As a result of these findings, in 1984 OPPD committed to an inspection of the Fort Calhoun Station reactor vessel thermal shield during the 1987 Refueling Ootage (References 1 and 2).
The purpose of this inspection was to ensure that the thermal shield and its sup) ort system were not degrading as observed at other Combustion Engineering (CE) plants.
In 1986, results of comprehensive research and analysis of the thermal shield degradation phenomena led to new information and monitoring.
techniques which were not available in 1984.
Based on the results of this new information, OPPD replaced the commitment.for a 1987 inspection with a commitment to conduct an ongoing thermal shield monitoring program capable of detecting precursors to internals degradation.
Should precursors to degradation be detected, OPPD committed to conduct an inspection and/or repair as needed.
flowever, at the latest, an inspection of the reactor internals would be conducted as required for the second ten-year reactor-vessel 151 during the 1993 Refueling Outage (References 3, 4, 5, and 6).
As part of the 1986 inspection deferral for the Fort Calhoun IVM and.
Station thermal shield, internals vibration monitoring (lyze)d on a data were collected and ana loose parte monitoring (LPH)llow for the detection of early routine basis.
This would a dec radation of the thermal shield su) port system.- In mid-1988, incications in the IVH data showed t1at the TS was exhibiting early signs of a loss of preload in some of the positioning pins.
This loss of preload manifests itself as inc.reased motion aetween the CSB and TS in the shell modes of vibration. Over a period of time, the increased motion has the potential to produce damage to the positioning pins and, ultimately, the support lugs.
A feasibility study was performed to investigate the engineering-and tooling preparation required to tighten a-partial or complete set of positioning pins to reinstate tfie desired coupling of the TS/CSB system. As-a result of this study, an inspection and repair program was initiated by 0 PPD.
The actual work was to'be performed with diver assisted tooling.
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The repair approach adaptad eas to visually inspect the condition of the positioning pins and to measure the amount of preload in the "as-found" state of the positioning pins.
The results of measurements would then be used to estabitsh the amount of preload required in the positioning pins to reinstate a long term coupled
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state between the IS and CSB. The calculation of the required positioning pin preload takes into account all factors affecting the positioning pin preload, including low leakage fuel management relaxatlon,fferential thermal expansion, radiat;on induced stress schemes di and hydraulic loads. Any positioning pins requiring replacement would be replaced with a pin of similar design and function, but with preload of a higher value than that provided during initial installation.
in essence, the changes to the TS were designed to reinstate the support system to its original coupled state with the CSB. A locking collar (as with the original design) was used to preload each positioning pin to the TS.
The locking collar was secured to the positioning pin and TS by mechanical crimping (Figure 3).
3.0 INTERNALS VIBRATION MONITORING AND INDICATIONS OF PIN DEGRADATION 3.1 Thermal Shield Inspection Commitment In 1984 OPPD committed to the NRC to perform an inspection of the fort Calhoun Station reactor vessel thermal shield during the 1987 Refueling Outage (References 1 and 2). A deferral justification for this ins)ection was subsequently prepared which allowed OPPD to replace tie commitment for the 1987 inspection with a commitment to conduct an ongoing thermal shield monitoring program capable of detecting precursors to thermal shleid degradation (References 3, 4, 5 and 6). The cornerstone of the deferral was internals vibration monitoring (IVM) since:
A.
Monitoring and data evaluation on a regular basis allows for detection of early stages of degradation of the thermal shield support system and, Evaluation of the IVM data to date (up to 1986)t system.
B.
had not indicated a change in the thermal shield suppor Should indications of thermal shield' degradation develop /or in IVM and LPM data, OPPD committed to conduct-an inspection and repair as needed.
From mid-1988 through Fall of 1990, OPPD evaluated IVM data developments which indicated the early stages of loosening of the thermal shield )ositioning pins.
Based on the evaluations and IVM indications, OP)D decided to inspect and repair the TS during the rather than at the scheduled end of Cycle 13 refueling outage,he end of Cycle 14.
20-year ISI refueling outage at t l
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3.2 IVH Data Reduction Prior to End of Cycle 13 Inspection Experience gained from the St. Lucie Unit I thermal shield program demonstrated that degradation in the thermal shield support system is detectable as frequency peak shifts in the spectra of the excore detector noise signals. Analytical models are used to establish the coupled and uncoupled frequency response of the thermal shield support system, in the case where the thermal shield uncouples from the core support barrel, there is a corresponding decrease in the frequency of the COS 20 and COS 30 modes of vibration (Table 1).
The C0S 20 mode, which is in-)hase for cross-core detector pair data, and the COS 30 mode, whic1 is out-of Phase for cross-core detector ) air data provide two identifiersoftheconditionofthetiermalshleldsupportsystem which can be tracked via a neutron noise monitoring program.
The COS 20 mode, with its much larger frequency decrease for loose positioning pins, is censidered to be the main identifier of the condition of the is support system.
The actual corres onding frequency peaks in the IVM data can vary from the anal tical predictions due to various neutronic factors assnciate with each fuel cycle.
Figures 4 through 6 show the trends observed in the IVH data for the degraded condition identified in 1988.
The baseline response was taken from IVM data obtained on September 16, he C05 20 in-phase mode. quency peaks were found atAlso, fr 1987. At this point, fre 11 llertz for t found as expected at 16 liertz for the COS 30 out-of-phase mode.
The figures also show that after June 1988, a clear )eak was also seen in the 8 to 9 Hertz range for the COS 20 mode (:igures 4 and 5).
Also, the 16 Hertz peak decreased for the COS 30 mode with a correspondinhH data up to December 1991 showed skmilar) trends.
increase in the 14 Hertz range (Fi ure 6 Subsequent t The IVH data indicated loosening of the thermal shield positioning pins.
LPH data from 1988 through December 1991 did not show signs of impacting of the positioning pins against the CSB.
Therefore, although the IVH data showed signs of loosening, the LPH data indicated that a complete loss of preload had not occerred.
4.0 DESCRIPTION
OF THE REPAIR APPROACH The approach developed for the fort Calhoun Station thermal shield was to first perform a visual inspection of the thermal shield su) port features (i.e., supgort lugs and positioning pins?, followed )y a measurement of the as-found" preloads in the positioning pins. The inssection information was evaluated by ABB/ Combustion Engineering for the)TS/CSB support system wasand a repair plan that provided long term structu (AB 3/CE resented to OPPD. Upon acceptance of the repair plan by 0 PPD, it was im lemented by ABB/CE.
The repair involved the replacement and prelo ding of seven lower positioning pins and four upper positioning pins.
5.0 "AS-FOUND" INSPECTION RESul.TS 5.1 Visual Inspection A complete external visual inspection of the support features (lugs and positioning pins) was conducted during the End of Cycle 13 outage.
The following summarizes the findings of the visual inspection:
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The external visual' inspection of the lower sixteen (16) positioning pins indicated no noticeable cracks, weld cracks, missing parts, misalignment, gaps, looseness, or 1
wear. The lower positioning pins were found in their correct position and in good condition.
B.
The external visual inspection of the upper eight (8) positioning pins indicated no noticeable cracks, weld cracks, missing parts, misalignment, gaps, looseness, or wear. The upper positionint pins were found in their correct position and in gooc conditlen.
C.
The external visual inspection of the eight (8? support lugs indicated no noticeable cracks, weld cracks, mnssing parts, misalignment, gaps, looseness, or wear.
The support lugs and support pins were found in their correct position and in good condition.
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in general, the overall condition of the thermal shield support system was found to be good.
There was no apparent' shifting or i
damace that would indicate a change from the initial installed condition.
5.2 Preload Inspection Due to tooling difficulties, "as found" pin preloads on all 24 positioning pins were not taken as planned.
Backup preload measuring equipment electrical-resistance coil method) was used ar.d could access on1 -11 of 16 lower positioning, pins and none of the eight upper post ioning pins.
The "as-found positionin preload measurements which were taken are listed in Table 2.g pin Two pins were determined n to be in contact with the CSB.
Three-additional positionin were found to have less than-25% of their original load. g p.,The inspection data indicated an overall condition that required repair.
6.0 DESCRIPTION
OF REPAIR RECOMMENDATION Based on the preload information obtained for the lower positioning pins, ABB/CE recommended an 11 pin repair to provids a high confidence, long term repair for the thermal shield.
The recommendation specified a lower odd numbered positioning pins. pins in addition to a set of sevenOPPD accept set of odd numbered top positioning and an 11 pin repair was performed.
With the absence of initial preload information for the top )ositioning pins, the following justification was given for working nn tie top positioning pins:
minimize relative motion between the) of the thermal shield is to The key to preventing loss (failure A.
support lug and the thermal shield and thus minimize wear. The restraint provided by the positioning pins fulfills that function.
Both bottom positioning
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3eam motion of the thermal shield relative to the lugs; the bottom pins play a larger part-in this than the top pins.
The top and bottom pins both provide restraint. against shell motion of the thermal shield relative to the lugs; the top pins play a larger part in this than the bottom pins.
Page 6
i 11.
Based on fluence and temperature gradients acting on the top and bottom positioning pins for the first 20 years of operation it was calculated that the radiation' induced' loss in preload in the, top
)ositioning pins could be considerably higher than that in the Jottom positioning pins. Therefore, more preload loss would be expected at the top.
At the top positioning pins elevation, the pins C.
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e at the top i
positioning pins can result in higher wear rates as a result of relative motion, which further increases the likelihood of gaps at the top positioning pins.
D.
In 1984, a thermal shield repair was conducted at Maine Yankee.
During this repair, eight out of 17 lower positioning pins were tightened and four of nine upper positioning pins were repaired.
Three upper positioning pins that had worked their way out of the thermal shield were replaced and one upper positioning pin that had a gap was tightened.
The lower positioning pin repair at Fort Calhoun Station in 1992 (seven out of 16 lower positioning pins) is-similar to the 1984-lower positioning p)in repair at Maine Yankee (eight out of 17 lower positioning pins.
Due to the lack of preload information th upperpositioningpIns,esesimilaritieswerealsoconsideredinthe where a four pin repair was required at Maine Yankee.
E.
Full power (100%) operation was calculated to result in a 24*F temperature gradient across the top positioning pins This temperature gradient causes a 0.014" increase in len th of the top positioning pins that works in the direction of keep g the pins tight.
If gaps exist, the gaps plus the effects of draulic loads and radiation induced relaxation could exceed the 0.0 4" and the positioning pins would be loose during operation.- It is only necessary for gaps at the top positioning pins to be on the order of 0.009" for this to occur.
Gaps on the order of several mils were found at the bottom positioning pins.
It was expected that larger gaps could occur at the top) positioning pins (see wear discussion and Maine Yankee experience, and that these gaps could increase with time due to wear.
It was, therefore, considered likely that no action on the top positioning pins and continuous full power-operation would not provide a high confidence, long term repair.
For the above reasons, in order to provide a high confidence long term thermal shield repair, ABB/CE recommended that a set of four top lositioning pins (every other pin) be repaired in addition to the seven sottom positioning pins. The ABB/CE analysis indicated that repair of additional pins beyond the selected four would not provide a significant benefit.
Since upper pin location 4 UP4) was found to be obstructed for electrical discharge machinin and UP7) were chosen for repair. g (E M), the odd pins (UP1, UP3, UP5, l
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7.0 REPAIR RESULTS 7.1 Pin Removal Aspartoftherepair{ Figure 7)). lower positioning pins were seven (7 removed and replaced After the removal, a visual inspection was performed on the pin contact face and the stellite pad on the CSB.
In all seven of the lower positioning pins wear was discovered as evidenced by shiny surfaces on the pin face and CSB stellite pads. A direct measurement of the amount of wear was not possible.
With close video camera examinations of the CSB stellite surface, the amount of wear was noticeable and judged to be on the order of several mils.
As part of the repair, four (4) upper positioning pins were removed and replaced (Figure 7)' After removal, a visual inspection was performed on the pin contact face and the bearing surface of the CSB.
There is no stellite on the CSB at the top positioning pin location.
In all four cases, wear was not noticeable.
The condition of the CSB was such that a lightly burnished surface was noticeable. No noticeable wear was noted on the removed top positioning pins.
In order to remove locknuts, a larger than anticipated EDM cut depth was required because of the larger than expected locknut welds.
In some cases, locknuts / positioning pins had to be-removed together.
This made usage of the old positioning pins impossible and all 11 positioning pins were replaced (Table 3).
During the removal of the lower positioning pins, six positioning pins were found not to be in contact with the CSB and one was found to be slightly loaded (Table 2). -During the removal-of the top positioning pins it was found that the odd pins had marginal preload(approximately5,000 pounds).
The marginal loads found in the odd upper positioning pins indicates a condition better than was expected.
Sufficient-preload had decreased from initial installation values '(approximately 10,000 pounds) to ' warrant reloading.
The positive positioning pins ensures preload reinstatement at the odd long term integrity for the support system. The reinstating of high preload on the odd positioning pins also-had the effect of closing potential gaps and increasing the existing preload at the even positioning pin locations.
7.2 Repair Preloads The re) air consisted of re) lacing and advancing bottom positioning pins Lal, LP3, LP5, LP7, L)9, LPl3 and LP15 to 9.45 mils of preload, and of replacing and advancing top positioning pins UP1, UP3 UP5 and-UP7 to 18.3 mils of posItionIngpincom)ression,thispreload.resultsinninemilsofp$n After accountin for advancement in the >ottom locations and 18 mils at the top.
The nine mils advancement of the lower positioning pins correlates to approximately 25,000 to 28,000 )ounds of preload in the lower pins-(Table 4).
The wear.found at t)e lower )ositioning pin locations- -
- implies that the initial =preload should )e as high as possible in order to achieve added margin against wear.
It was decided to install preloads higher than the desired minimum to include margin for wear and measurement uncertainties..
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Preloading of odd numbered positioning pins resulted in increased preload or gap closure in even numbered positioning pins.
The non repaired pins " pick up" approximately 58% of the repaired positioning pin displacement at the top and approximately 16% at the bottom. Comparison between the as-found readings of the accessible even numbered lower positioning pins (Table 2 and the calculated preloads after repair (Table 4) show the incre)ase of the non-repaired positioning pins.
Since no as-found preload data were available for the top positioning pins, calculated preloads for the repaired top positioning pins with 18 mils of installed displacement range between 9,300 - 14,000 lbs of preload.
Depending upon the initial condition of the non-repaired upper positioning pins, the calculated 10.4 mils displacement " picked up" by ti htening the odd numbered positioning pins may range from 0 lbs pin still gapped)he initial pre-repair load (Table 4).to increasing.the positioning pin loa above t 7.3 Repair Evaluation Evaluation of the repair indicates that a long term fix with adequate margins has been instituted on all of the repaired positioning pins and that life on non-repaired pins has been extendedormarginimproved.
It is concluded that all of the design objectives of the recommended partial r2 pair have been met:
A.
The repair provided a coupled CSD and TS system, B.
The repair introduces little concern for lug wear, and C.
The natural frequencies of the repaired CSB and TS system do not differ from those associated with the system at original installation.
Post repair IVM results support the objectives of the field repair. -The thermal shield repair is reflected in positive s ectral changes in the C0S 20 and COS 30 shell modes of vibration
( igures 8 -
11).
It is concluded that these. positive spectral cianges support the fact that significant thermal shield to core-support barrel tightening was achieved.-
-l Page 9-
LIST OF TABLES AND FIGURES 4
4 Page Number LIST Of flGURES 1.
Reactor Internal Arrangement 11 2.
Thermal Shield Support System Original Installation........
12 3.
Thermal Shield Support System Replacement Pins and Locknuts....
13 4.
0* Phase PSD, Ac x Bc, 1987 and 1988 14 5.
0* Phase PSD, Bs x Cs, 1987 and 1988 15 6.
180' Phase PSD, Ac x Dc, 1987 and 1989 16 7.
Positioning Pin and Lug Location - Developed View of Thermal Shield. 17 8.
Dc x Ac, O' Phase PSD Lowers,1989 and 1992............
18 9.
Ac x Bc, 0* Phase PSD Lowers, 1991 and 1992............
19 10.
Ac x Bc, 180' Phase PSD Lowers, 1989 and 1992...........
20 11.
Cs x Bs, 180* Phase PSD Lowers, 1989 and 1992..........._. 21 LIST Of TABLES 1.
In-Water Modal frequencies (Hertz) vs. Support System Conditions 22 2.
Comparison of As-found Loads from Coil Inspection and found Conditions 23 3.
Repaired Conditions........................
24 4.
Repaired Preloads and Displacements......_..........
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'c
- 1 x 10 U2/Hz
- y
's 1 x 10 6-20-89 4
DECREASE IN COS20
- g2fg LOOSE CONDITION FREQUENCY
. $ y $ g4 6-9-92
(
RANGE FROM 89 TO POST-REPAIR 92 DATA 1 x 10* '
's 1 x 10*
\\_
f,
\\
l' l'.
- ^
1 x 10
'f, 4
J%'
~ ( 'u 1 x 10*
'i
's 1 x 10 O
5 10 15 20 25 FREQUENCY (Hz)
FIGURE 8 m.
Ac x Sc 0* PHASE PSD LOWERS 6-9-92 I
- - - 30-91 4
1 x 10 b
4
- 1 x 10 4
~
1 x 10 t
- 1 x 10*
m 5'
1 x 10"
",\\
COS20 LOOSE CONDITION U2/Hz s
PEAK IN 91 DATA IS NOT
- 1 x 10*
6-9-92 EVIDENT IN 92 DATA
[
U2/Hz 1 x 10*
fi 12-30-91 4
l
- 1 x 10
[\\
j 1x10*
' /, %, /
i
'V j.
1 x 10*
l 1 x 10 0
5 10 15 20 25 i
FREQUENCY (Hz)
FIGURE 9 1
Ac x Bc 180 PHASE PSD LOWERS 6-9-92 1 x 10*
- - - 20-89 1x10*
d ~
'v,,,
1 x 10
- s s
4 1 x 10
?U2/Hz f
N DECREASE IN COS30 SS 6-9-92 1 x 10* ~
sf
's LOOSE CONDITION FREQUENCY U2/Hz
- /
\\
RANGE FROM 89 TO 92 6-20-89 y
4 1 x 10 i
f 1 x 10* ~
'4 k *,/.#-/.
\\
0; 1 x 10*
\\
Ml
' 'I t 1 x 10" ~
\\
kj f y
k'
,/
(
1 x 10#
1 x 10' 0
5 10 15 20 25 FREQUENCY (Hz)
FIGURE 10
Cs x Bs 180 PHASE PSD LOWERS 6-9-92
- - - - 20-89 4
1 x 10 i!
- 1 x 10*
4 -
'w'A 1 x 10
- 1 x 10*
.~
'd DECREASE IN COS30 1 x 104 i'
LOOSE CONDITION FREQUENCY U2/Hz 2
IN POST REPAIR 92 DATA U2/Hz
- 1 x 10*
6-20-89 6-9-92
's
'e L
1 x 10* '
n, w,
s s
- 1 x 10*
~
1 x 10 t
.i t
. p-1 x 10" 1 x 10*
0 5
10 15 20 25 FREQUENCY (Hz)
FIGURE 11
IN-WATER MODAL FREQUENCIES (HERTZ)
VS. SUPPORT SYSTEM CONDITIONS TIGHT NOMINAL ALL PINS NOT CONDITION 1992 AS-LEFT TOUCHING CSB H0DE (COUPLED)
NOMINAL CONDITION (UNC00 PLED)
C0S 20 12.5 12.5 7.9 C0S 30 16.3 16.2 14.9 f
TABLE 1 Page 22
~
COMPARISON OF: AS-FOUND LOADS FROM COIL INSPECTION AND FOUND CONDITIONS Pin As-found load from Condition found during the design.
con inspec+Jon, bs romoval step of the repair a g; g 9 y2rwm:y:-;c;; <i:g+ytpyp
~,:,.9: g.
LP1 NO ACCESS GAP LP2 14038 t#A W3 GM GM LP4 NO ACCESS WA US GM GM LP6 5883 WA LP7 2052 GAP WA LPS 7689 LP9 NO ACCESS GAP LP10 9838 f#A LP11 12009 f#A WA LP12 11984 LP13 1769 UGHT LOAD LP14 259 N/A LP15 NO ACCESS GAP -
LP16 NO CALL WA
-@isG a?lsOK:vh'ilts#EQXM MO 4NOW;igtf.p.1;$hicihi UP1 NO ACCESS 4900 bs UP2 NO CALL WA l
UP3 NO ACCESS NO ESTIMATE, PIN LOADED I
UP4 NO CALL WA-UPS NO ACCESS NO ESTIMATE, PIN LOADED UP6 NO CALL WA
-UP7 NO ACCESS 6529 bs UP8 NO ACCESS WA l'
l l
TABLE 2 1
Page 23 L
REPAIRED CONDITIONS Pin Degree 1.0.
Pin Locknut New pn design.
location letter repace S/N cut length 'L' (note 1)
S/N (note 2) ny
'. 'i : Tk.1%
, e:;.
cyg.T. 8 M;% '.g %W LP1 22.5 L
02 03 4.250 LP2 45 M
F#A LP3 67.5 N
10 -
10 4.625 LP4 90 0
N/A LPS 112.5 P
03 02 4.718 LP6 135 A
N/A LP7 157.5 B
04 04 4.417 LP8 180 C
t#A LP9 202.5 0
08 08 4.292 LP10 225 E
N/A LP11 247.5 F
N/A
' P12 270 G
N/A LP13 292.5 H
09 09 4.700 LP14 315 i
N/A LP15 337.5 J
11 11 4.29 LP16 360 K
N/A
$9;%%L $8%%4 % 5] Q $?2Wl4 ?%C?? % %#P RA M b UP1 13 R
06 06 4.656 UP2 58 N/A UP3 103 T
07 07 4.688 UP4 148 U
N/A UPS 193 V
05 05 4.615 UP6 238 W
N/A UP7-283 X
01 01 4.760 UP8 328 Y
N/A
- 1) letter 10 of each pn location correspon6ng to the markings used during Wtial construction
- 2) Indcates 'as buitt' dmension of the repacement pn longth 'L' TABLE 3 Page 24
REPAIRED PRELOADS AND DISPLACEMENTS Pin Calculated Olsplacement, mils design.
preload, Ibs Installed Calculated g,; cm
- wn
' vc::
n=%%
LP1 27,900 9.0 4.8 LP2 15.331 LP3 28,200 9.0 7
LP4
- UNKNOWN LPS 28,050 9.0 2.6 LP6 8,303 LP7 26.700 9.0 3.2 LP8 10,250 LP9 25,050 9.0 52 LP10 16,919 9.0 LP11 28,375 6.5 LP12 20,820 LP13 24,600 9.0 0.8 LP14 2,508 LP15 27,750 9.0 7
LP16
- UNKNOWN
'Til / % 3 N M iWDDE MDSIENf t
M@h?
UP1 9.300-14,000 18.0
- * + 10.4 UP2
- * +(0-8100)
UP3 9,300-14,000 18.0
" + 10.4 UP4
' +(0-8100)
UPS 9.300-14,000 18.0
- * + 10.4 UP6
' +(0-8100)
UP7 9,300-14,000 18.0
" + 10.4 UP8
" +(0-8100)
- The unknown values were assumed to be gapped for conservatism
" Loads and dsplacements in addtion to existing preloads and dispiacements TABLE 4 l
Page 25
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REFERENCES 1.
Letter No. LIC-84-090 to J. R. Miller (NRC) from W. C. Jones (OPPD)
Dated April 4,1984, fort Calhoun Station Thermal Shield Inspection Docket No. 50-285, Letter to W. C. Jones (OPPD)hermal Shield from J. R. Miller 2.
(NRC) Dated May 4,1984, Fort Calhoun Station T Inspection 3.
Letter No. LIC-86-421 to A. C. Thadani (NRC) from R. L. Andrews-(0 PPD) Dated August 28, 1986, Fort Calhoun Thermal Shield Support System Inspection Deferral 4.
Docket No. 50-285 Letter to R. L. Andrews (0 PPD) from W. A. Paulson (NRC) Dated February 12, 1987, Thermal Shield Support System Inspection Deferral - Fort Calhoun Station, Unit No. 1 Dated August 2, 1983, Evaluation of th(NRC) from W. C. Jones (0 PPD)
Letter No. LIC 83-189 to R. A. Clark 5.
e Impact of a Thermal Shield Support System Failure in the Fort Calhoun Reactor 6.
Letter No. LIC-87-673 to NRC Document Control from R, L. Andrews (0 PPD) Dated October 13, 1987, Additional Information on the Fort Calhoun Internals Vibration Monitoring System l
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Page 26
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