ML19210C111

Results of Control Element Assembly Tube Guide Insp Program, Nonproprietary Version

ML19210C111
Person / Time
Site:	Calvert Cliffs
Issue date:	11/08/1979
From:	ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY
To:
Shared Package
ML19210C109	List: ML19210C107 ML19210C111
References
CEN-118(B)-NP, NUDOCS 7911130283
Download: ML19210C111 (30)

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Combustion Engineering, Inc.

Results of the CEA Guide Tube Inspection Program Calvert Cliffs Unit tio. 2 Docket flo. 50-318 CEft-118(B)-tiP flovember 8, 1979 1320 086 123 7911130 &

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e LEGAL NOTICE THIS REPORT WAS PREPARED AS AN ACCOUNT OF WORK SPONSORED BY COfACUSTION EfJGINEERING, INC. NEITHER COMBUSTION ENGINEERING NOR ANY PERSON ACTING ON ITS DEHALF:

A. MAKES ANY WARRANTY OR REPRESENTATION, EXPRESS OR IMPLIED INCLUDING THE WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE OR fAERCHANTABILITY, WITH RESPECT TO THE ACCURACY, COMPLETENESS, OR USEFULNESS OF THE INFORMATION COfjTAlfJED IN Tills REPORT, OR THAT THE USE OF ANY INFORMATION, APPAflATUS, METHOD, OR PROCESS DISCLOSED IN Tills REPORT MAY NOT INFRINGE PRIVATELY OWNED RIGHTS;OR B. ASSUMES ANY LIABILITIES WITH RESPECT TO THE USE OF,OR FOR DAMAGES RESULTING FROM TiiE USE OF, AfjY INFORMATION, APPARATUS, METHOD OR PROCESS DISCLOSED IN THIS REFORT.

1320 087 O

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I. Summary .r A total of 128 irradiated fuel assemblies and 5 control element assemblies were examined at Calvert Cliffs II during the E0C-2 refueling period. The purpose of this inspection program was to:

a) Determine the condition of sleeves af ter one cycle of operation with respect to crimp size, wear and ability to resist axial movement.

b) Monitor CEA condi. tion after operation in sleeved and/or unsleeved assemblies.

c) Determine the condition of the unsleeved demonstration assemblies.

The results of the sleeved assembly inspection confirmed that; a)

There was operation. no observed sleeve wear from control rod motion during b) There is adequate resistance to axial movement for sleeves with the new crimp geometry after one cycle of operation.

c) Assemblies sleeved acceptable crimp in 1978 in the unirradiated condition had sizes.

d)

The new procedures used for sleeve installation in irradiated guide tubes oroduce adequate crimp sizes.

The results of the CEA inspection showed light control element wear comparable to that observed at other sites.

The inspection of the unsleeved demonstration assembliesf

.. --= . -

1320 088 ee II Introduction Past inspections of sleeves installed and operated in the guide tubes of Combustion Engineering (CE) fuel assemblies confirm that the sleeve is effective in protecting the guide tube from wear in control element assembly (CEA) locations. This conclusion is based on inspections of

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[_ ] sleeved guide tubes that have been operated in CEA locations in Calvert Clif fs-1, Millstone-2, and St. Lucie-l.

These inspections did reveal, however, that some sleeves, particulary those installed in irradiated fuel assemblies, had retaining crimps that were shallower than specified. Because at less than operating temperatures the shallow crimp could conceivably allow the sleeve seating to be shifted by CEA drag forces, CEA movement was restricted for system temperatures less than 400F.

This restriction was instituted at Calvert Cliffs-2 as well as other CE plants as a preventive measure, although there were no indications that any such sleeve movement had actually occured. .

For Cycle 3 at Calvert Cliffs-2. sleeved fuel assemblies carried over from Cycle 2 and sleeved, fresh Batch E assemblies will continue to be used in CEA locations. Table 1 lists by batch the quantity of fuel assemblies containing sleeves for Cycle 3 as well as the time of sleeve installation.

In light of the shallow crimp findings, the Calvert Cliffs-2 inspection program at end-of-Cycle 2 was intended to determine the crimp sizes in sleeves installed at the beginning of Cycle 2, allowing CE to re-crimp where necessary. This would obviate any need to continue the CEA movement restriction. The categories of sleeved fuel assemblies inspected include:

(la) fuel sleeved prior to irradiation, exclusively Batch D, and, (Ib) fuel sleeved af ter irradiation, Batch C. An inspection of LEA's was also included to monitor for any wear effect of sleeves on the CEA finger, in addition to examining sleeved fuel assembly performance, the program also examines the guide tube wear performance of the modified test assemblies (Category 2).

These assen.blies have beenismodified intendedto(

t6 reduce CLA/guice tube wear by{

} This" design

]

The l'ocations of the fuel categories of interest placed under CEA's remain as October pictured in the Cycle 3 Core Map supplied earlier in CEM-ll6(B)-P,I 8,1979.

The methods used to conduct the inspections of fuel and CEA's include visual examinations and eddy current measurino techniques.

These techniques appendix and the devices employed are discussed at length in the to this report. The eddy current techniques developed for these inspections have also been incorporated as a quality control step for the initial installation of sleeves and for any re-crimping repairs.

1 Ltr. R.C.L. Olson (BG&E) to R. W. Reid (NRC) dated 10/10/79.

1320 089 '

TABLE 1 Sleeved Fuel Assemblies in Calvert Cliffs-2, Cycle 3 flumber of time of Fuel assembly Number of assemblics ,

!! umber of unden.CEA's in Cycle 3 '

status at time Batch Assemblies in Assenbl ies sleeve Cycle 3 containing sleeves installation) of installation B 1 BOC3 irradia ted 1 B0C2 irradiated 12 C 68 16 B0C3 irradia ted 00C2 unirradiated 24 0 84 unirradiated 24 E 64 B0C3 77 TOTALS 217 I BOC, beginning of cycle 9

'unsleeved D assemblies are the modific'd test assemblies O

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III. R

_lesul ts_ and Dis _cussinn A. Fuel Assembly Inspection

1. Eddy Current Test Results for Wear Sleeves A

all total of[ r6 turning to the core for CycleAll3.I" sleeves guide sleeves had tubethe wear s short (3/S") crirap geometry. The results of the inspection for crimp size are listed by assembly type in Table 1.

The table deconstrates that all sleeves in assemblies returning to CEA locations for Cycle 3 satisfy the [10] mil minimum crimp size criterion. The data also confirm the fact that the Batch D assemblies sleeved in the unirradiated condition in 1978 had acceptable crimp sizes. All 1979 sleeve installations in irradiated fuel assemblies were performed under a revised procedure, which produced the desired crimp scometry. .

As expected from observations on other plants, undersize crimps were observed in the Batch B and C assemblies in which sleeves had been installed in 1978 after irradiation. These sleeves were successfully recrimped for those bundles scheouled to return to CIA locations.

No wear was detected on any of the inspected sleeves which had been used in CEA locations during Cycle 2. The sensitivity of the ECT equipment to sleeve wear was not as great as during tne Spring,1979 inspections at Millstone 2, Calvert Cliffs 1, and St. Lucie 1, due to the fact that the thrustToof be theassleeve inscettion accurate at Calvert as possible, this rcouirecCliff s 2 was toward crimp size.

somewhat modified equicment and calibrations. Significant wear on the

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sleeves would still have been ooserved, if present.

The installed sleeves have between4,,

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r

.' In the case of the,_ , ,,

1320 091 J

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2. Demonstration Asserrbly Eddy Current Test Results Eddy current test results for the [ 13 demonstration assemblics C .

. --lare summarized below.

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~ [ Bobbin Coil Voltage]

Assembly CEA Tvpe Range Average 1

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locations ror Cycle 3..] These assemblics are not . . . returning to CEA L

1320 092 5

3. Sleeve Pull Test Results .-

r A total of[ ysleeves were pull-tested to a[

sleeves were in discharged Batch B fuel assemblies.

I All As expected, these sleeves with their improved crimo geometry exhibite(

at least as much resistance to pullout af ter operation as sleeves with the old crimp type. As noted in figure 1, the pull test results of sleeve

• with the long' crimp geometry indicate that no movement occurred with a minimum crimp size of[ The testing performed on the 16 sleeves Nith the,new crimp type e wher[],the crimp size ranged fr uresulted in ne t .ectable movenent.

These results further s..pport the [ ] mil minimum crimp requirement, and justify the replacement of the pull test during installation with the eddy current inspection for correct material upset.

IV. Conclusions

1. All sleeves in fuel assemblies returning to CEA locations have acceptable crimp sizes.

2. The revised procedure for the installation of new sleeves results ii) the proper crimp sizes.

3.

There was no observed sleeve wear from control rod motion during operation.

4. The performance of the unsleeved demonstration assemblies [

. ... . i 5.

Resistance to axial movement for sleeves with the new crimp geometry was verified. Since all sleeves in CEA locations for Cycle 3 have adequate crimps, the 4000F operating res triction on control rod movemei need not be imposed.

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1320 093

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TABLE 1 ilumber Assys. Under CEA Crimp Size Average Category Inspected Cycle 3 Range Crito Size

1. Sleeved in 1978 __ ,_

a. Batch D (sleeved fresh) 24 yes, 44'no

b. Batch C (sleeved irradiated)

1. Worn Assemblies no

2. Unworn Assemblies 12 yes

c. Batch 8 (sleeved irradiated) Discharged .

3. Sleeved in 1979 .

a. Batch E (sleeved fresh)  ;

24 yes, 40 no

b. Batch C (sleeved irradiated) .

yes

c. Batch 8 (sleeved irradiated) yes 1

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• data from a representative sample of five rs; >

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• • data from a representative sample of seventeen w

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B) CEA Inspection

1) Eddy Lurrent Test Results CEA's were eddy current tested during the Calvert Cliffs II EOC 2 shutdown, to detect of the CEA's were located in sleeved assemblies during the second cycle and ,

of the CEA's were located in unsleeved cemonstration asserc.blies of a modificJ design. The CEA's operated at essentially the all rods out "AR0" position for Cycles 1 and 2.

This operating mode corresponds 'to a nominal CEA insertion into the assembly of 161,2 inches. However since January 1978, the CEA progranming sequence has been modified by

. The CEA's inspected, eddy cur" rent test . .

and The

)of any indications observed are presented in Table 2.

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indications are located approxicately at _

CEA exit from the top of the fuel assembly considerina the modified CEA 4

A total of 'I fingers tested,

. .I i ndications were observed on theI~ '

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1 ranging from ,J

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. These were probably caused

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by the CEI nrogramming during Cycle 1 and 2 as well as ,

between Cycles 1 and*2.

i 1320 096

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The average indication is[

' rith a ,tmutard deviation of Based on the ECT signal (Table 1), the average indication corresponds to f the CEA finger.

,j leading to scme of the actual wear see Reference 1. No ECT indications associated with

, j wear were observed.

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• - TAkE 1 Calvert Clif fs II, EOC-2 Eddy Current Sicnajf Correlation for CEA Test Calibration Calibration 1 Wear Simulations Standard Deviation

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1320 098 M

e' TAEi.E 2 I ] Eddy Current Results Calvert Cliffs 2 CEA, Distance Abovo CEA In Cycle 2 CEA Maxir.um )ofCEA r.'un be r Assembly Bank .i 1 in.

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x p TABLE 2 (cr>t.)

Distance Above CEA In Cycle 2 CEA Maximum ,,

of CEA i; umber Assembly Bank ,

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2) Visual Inspection Results CEA's were visually inspected using an undentater periscope. .

In additi.

< ) were examined in detail over their entire length.

fingers on . .

l The results of were examined in detail over the( J these visual examinations are summarized in Table 3 and confirm satisfactory operation.

1320 101 e

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3) Discuslipjl Both the visual inspection ano eddy current test results were,in general, similar to those observed at Millstone II and Calvert Cliffs I carlier in 1979 (See Reference 1). The maximum eddy current signal of

) This estimate nealects the effect of any on the ECT signal and is well under the '

fdiscussed in Reference 1.

The visual examinations also confirmed satisfactory CEA performance after two operating cycles and no anomalies were observed. The

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.Ifound at the elevations as well as

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the CEA were similar in. nature to those observed at Millstone II

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and Calvert Cliffs I during previous inspections.

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Reference

1. " Response to Request for Additional Information CEA Guide Tube Inspection ora ram Ca yt Cliffs i:o. 2," Docket f!o. 50-313, CEft-116 (L;-P Jated October 8,1979 (Ltrs. R.C.L. Olson (BGSE) to R. W. Reid (ilRC) dated 10/10/79) _

1320 102

• T,b;i.E 3 CEA Visual Inspection Results from Calvert Cliffs II EOC-2 Approximate Elevation CEA Finger _ Description Extent i From( )_

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1320 103

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CEA Vf'sual Inspect. ion Resul t.s f rom Calve ]ii ffs !! EOC 2 Approxirnate Elevation CEA Fincer Description Extent 1 _ from(,_]_

1320 104 9

TAB . 3 (cont.)

CEA Visual Inspection Results frc:a Calvert Cliffs II EOC-2 ,

Approximate Elevation l

From(

CEA Finger Descriotion Extent }

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1320 105 cn.

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APPEjgl,X, Eddy Current Testing [ ~,]of sleeved guide tubes is performed for the pu poses of determining if sleeve wear has occurred or if an adequate guide tube expansion (crimp) exists. The ET systens employed for each of these purposes are nearly identi-cal,thedifferencesbeing[

] Both systems can be employed for qualitative estimates of features other than their p rimary purposes, i.e. , the(

']Amoredetaileddiscussicaofea$hsystemfollows. -

[__ ]EddyCurrentTest for Sleeve !! car The equipment used during Eddy Current Testing for sleeve wear consists of an(

] Teac tape recorder, Brush strip chart recorderanda[ ]

cddy current coil probe. Once the system components are interconnected, the probe is inserted into a standard to allow system balancing and calibration.

The standard used for calibration of the sleeve wear sys tem consists of(

] Other minor adjustments are made to ensure a uniformity of testing a therefore reproducibility.

'is pcint the( ,

} and then withdr:ren. As the probe is w..hJ cwn the eddy current signals are recorded upon both magnetic tape for record pe .c s '.! upon a strip chart for immediate assessment of the test quality w genar.A sleeve condition.

A t:<ical cddy current tracefromthe{ 7 is shown in Figure I belcw tae sleeve wear s tandard diagram. Each portion of the 'iiinnal is aligned with the a,ap'icabic area of the standard for easy reference. In the event that wear is detec-ted, a second trace is shown to indicate the differences from the unworn sleeve trace which w>uld occur.

The traces taken from fuel assemblics which were being inspected for wear have been used fo. .urposes other than that originally intended. An estimate of the guide tube

- {service unde r a Control Element Ascenbly (CMN) .

]wasnade in an effort to determine whether or not it was adequate for

!M r e recently a review of the t races

'for the sleeve expansion rc len was made to detarnine whether or not any sleeve thrvn f u riqure II .

Atypicaltracefora{ is om o g'y se djL1h m

, 1320 104

- --- - . Eddy Current Test for Guide Tube Expans' ion (Crimp) Size The sane equipment as listed for sleeve wear testing with a[

also used during an{; 1]cddycurrent test. The(_

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_]Again, the probe is inserted

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into a standard to allow system balancing and calibration.

The standard for calibration of the guide tube expansion size system consists of[

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, j Again, other minor adjustments are made to ensure a uniformity of testing and reproducibility. Set-up and calibration of thc[ .

2]for determining guide tube expansien size is complete at this point.

During use, the probe is inserted into the desired sleeved guide tube to a point below the bottom of the sleeve and then withdrawn. As the probe is withdrawn the eddy currcn signals are recorded as they are in the sleeve wear test. A typical cddy current trace fromthe( f]is shown in Figure III. Each area of the guide tube sleeve is aligned to a correspending portion of the eddy current trace. [ ,

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The[j ' -] eddy current system for guide tubc expansion size is calibrated for guide tube expansion sizes, but can be used to provide a qualitative estimate for ti sleeve installation as a whole. [ 3C

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CALIBRATIO:I CUilVE Foil EDDY CURREI!T '# Jt ;G OF GUIDE TU3E EXP/J:310:13 ACroupof( ]siceved guide tube sections were physically m.sured for the chance in outside diteeter es a result of guice tube exp. -ion and -

Vere ther eddy current tested. The attachcd Grupil depicts the actual data Points and abows a best fit line as the res ult c f r5 linear recrert ion analy-sis. This resultant curvo forms the basis for converting Eddy Current Testin6 data to best estinate cuide tube expraision si:.es (ditenatral).

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Eddy Current Testing of the Control Element Assemblies C

.]isusedinconjunctionwithanEM3300 Eddy

. Current Tester, a Fil magnetic tape recorderi^$ strip chart recorder to perform the eddy current testing upon CEAs.

[ .

]in preparation for eddy current testing of the CEA fingers. __.A standard (Fig. V) is employed to balance and calibrate the response from

[. .

The standard is fabricated from tubing of the same material and nominal dimensions (0D and wall thickness) as the CEA finger and incorporates machined features of various sizes and extent so that the CEA eddy current system response is known over a range of possible wear configurations .

When the system has been balanced and calibrated, a CEA is inserted into the

[ ]until approximately the [ ,,

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