ML20148J022

Myap Reactor or Oper W/Modified CEA Guide Tubes.Defines Guide Tube Wear Observed in C-E Reactors & Describes Modifications Which Will Prevent Further Wear During Cycle 4

ML20148J022
Person / Time
Site:	Maine Yankee
Issue date:	11/09/1978
From:	ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY
To:
Shared Package
ML20148H993	List: ML20148H989 ML20148J022
References
CEN-093(M)-NP, CEN-93(M)-NP, NUDOCS 7811150099
Download: ML20148J022 (86)

Text

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I COMBUST 10tl EllGillEERiflG, IllC. 1 v 9 .

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• MAlf1E YANKEE REACTOR OPERATIOlI WITH I40DIFIEDCEAGUIDETUBES l

CEN-93(M)-NP  !

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e Combustion Engineering j

,1978 I

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LEGAL NOTICE ,

This report was prepared as an account of work sponsored by Combustion Engineering, Inc. Neither Combustion Engineering nor any person acting on its behalf:

A. Makes any warranty or representation, express or '

implied including the warranties of fitness for a particular purpose or merchantability, with respect to the acc" racy, i i completeness, or usefulness of the information conti ned in this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately '

owned rights; or B. Assumes any liabilities with respect to the use of, or for damages resulting from the use of, any information, apparatus, method or process disclosed in this report.

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00MBUSTI0tl EtlG1tlEERIriG, INC.

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. MAltlE YAt1KEE l

REACTOR OPERATION WIT)!

MODIFIED CEA GUIDE TUBES _

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v CEN-93(M)-NP e

Combustion Engineering

, 1978 Y

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MODIFIED GUIDE TUBES

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i I. INTRCDUCTION A. Fttpose B. Applicability C. Sunnary ,

II. OBSERVATIONS.

A'. Summary-l B. Results III. RESOLUTION-GUIDE TUBE SLEEVING l A. Description -

B. Prevention of Further Wear '

C. Functional Performance of Fuel Assembly IV. REACTOR OPERATION A. Mechanical Integrity B. Analyses C. Test Programs V. TIELD INSTALLATION OF SLEEVES I A. Procedural Methods B. Equipment & Personnel Qualifications C. . Site Quality Control D. General Considerations i

VI. DEMONSTRATION FUEL ASSEMBLIES _

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e I. Introduction A. Purpose _ ,

The purpose of this report is to provide the NRC with information Y

which will support reactor operation for Maine Yankee Cycle 4.

This report defines the guide tube wear which has been observed in C-E reactors and describes guide tube modifications which will This report prevent further wear of guide tubes during Cycle 4.

demonstrates that reactor operation with guide tube wear and modi-l fications does not impact the health and safety of the public. J This report bases its conclusions on the data avaliable to Combus-Combustion Engineering tion Engineering through June 15, 1978.

is not aware of any newer information which would change the conclu-l

' sions of this report. If additional technical information becomes I available or final verification of the data in this report leads us to change any of the conclusions, we will insure that the NRC staff

• ~-

is provided with that information.

B. Applicability Although certain sections of this report contain statements which are generic to other Combustion Engineering designs, this report l

is specifically applicable to Maine Yankee.

Detailed inspection results from Maine Yankee Cycle 4 are not yet It is, however, the opinion of Combustion Engineering available.

that any guide tube wear conditions observed at Maine Yankee  ;

will not be significantly different from the observations and analyses

'; described in this report.  !

i Should any condition be observed which would invalidate that

, 7 conclusion, the NRC staff will be provided with that information.

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i C.. Sunmary.

A number of fuel guide tubes have been inspected at Some operating of react whose fuel and NSSS were supplied by Combustion Engineering.

The wear areas the guide tubes have been found to contain wear areas. In y are the results of vibratory motion of the CEA in the guide tube.

some cases this wear has resulted in a wear open'ing (penetratio of the guide tube.

Extensive analyses have been performed to assess the thermal I

hydraulic performance and structural integrity of fuel assemblie These analyses have considered both normal 1

with worn guide tubes.

The results of these analyses.sup. port the .~

and accident conditions.

i conclusion that the ability of*the core to maintain its cool'able '

geometry and the ability of the CEAs to scram, as required by safety analyses, are not significantly affected by the guide tube

1. Wear. ,

Although it is demonstrated that fuel assemblies with worn guide tubes can be operated safely, some of the fuel loaded into the reactor core for operation in the next cycle will be modified.

~

These fuel bundles will be modified by the A description of this addition of a stainless steel sleeve.  !

sleeve is contained in Section III and methods for installing 4

the sleeve in the worn guide tubes are described in Section V.

Analyses have been performed to demonstrate that no adverse on core thermal-hydraulic performance will occur due to the presen t

of these sleeves.

E In addition, tests have been run to verify the acceptability 1

of,the use of sleeves.

'Since the react'or will be shut down for refueling This sleeves will

~

inserted at this time prior to returning to operation.

fuel modification will be maJe to any fuel bundic which will be v

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_ . . . _ . _ . _ . . _ , . . . . _ . ~ . _ . ~ . _ . , . . , _ , _ _ _ , ~ _ _

used in a wear location (under a CEA) during This Cycle 4 in ord prevent wear of the guide tube during reactor operation l heduled

• .w ill result in the modifications of l

wear because only previously unw'orn bundles are for use in CEA locations.

in Cycle 4 in that the core's centralThe fuel assembly whic reason a CEA will not be sleeved or modified in any way. i for this is that this is a test assembly which is scheduled Precedence assembly and detailed inspertion at the end of Cycle#14. -

for non-sleeving of a single central bundle exists in BG&E The central assembly is a low wear core and St. Lucie Unit #1. Additionally, we are proposing that} {

location in all plants. The pur-demonstration bundles be included in Cycle 4 under i CEA's.

pose of these is to demonstrate the efficacy of potential

{}ofthese changes to mitigate or elim.inate guide tube wear.. lin their gu assemblies will have. . A more employ modified the other' detailed description of these demonstration bundles is giv Section VI.

Further, Combustion Engineering has recommended d '

' ' assemblies st.o be used in other core locations should be unless they meet the following criteria:

i

1. Seismic stresses are less than unirradiated stress, and;

2. Wear openings are not present.

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i II.

Maine Yankee Eddy Current Test Summary.

m.

A. Summary _

and probes

~ Guide tube eddy current inspections with were performed at Maine Yankee in order to characterize guide tube

~~

, condition. A total of guide tubes in _ .l.individualfuel

__ I assemblies discharged from either Core I, IA, or II were eddy current tested in the spent fuel pool. Four of these assemblies contained neutron sources during their lifetime instead of CEAs.

ltest data a total of( l guide tubes Basedonreviewofthef '

probe in ,_ ldifferent fuel assemblies were tested with the' to ch$racterize the amount of guide tube material removed aY a w The number of guide tubes tested by eddy current relative location.

to CEA residence time are sunvnarized in Table II-1.

The testing technique employed at Maine Yankee was similar to that described in Reference (1). The'results of the inspections are

~

summarized below.

B. Results .,. _

f for each of the Core I, IA, The average maximum _

i or 11 assemblies tested are shown in Figures I*i-1,11-2, II-3, and II-4. CEA locations for the .- Maine Yankee core are shown in Examination of thel. , indicates that there is Figure 11-5.

The outer dual CEAs (C and A no definitive radial pattern of wear.

Banks) do show relatively higher average assembly wear tnan othe should be noted that Maine Yankee is a three-loop plant witn three outlet nozzles while other C-E plants, namely St. Lucie-1, Calvert Cliffs-1, and Millstone-II, have 2 loops with 2 outlet nozzles.

' Average

-- ] for fuel Batches A, C, and D as a function j of CEA residence time and cycle operating length are summarized b V

II-1 l' '

i Average fuel CEA Residence Operating Time (lles ). All Guide Tubes

• __

Batch Time ....

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• Those with withdrawn CEAs only.

d Bundles under the regulating CEA banks (4 and in the 5 during Core I, a Bank same core.

5 during Core IA) do exhibit less wear t h time.)

Figure II-6 presents cumulative frequency distributions of t coil _,for Batch A, C, and D guide tubes.

maximumobservedi _ lies was These data show that the overallr- wear less than that in Batch A, even though the core observed areresidence on ly tim in The majority of the Batch D assembly average No signifi-identical .

the order of half that for corresponding Batch A assemblies. loca ted cant indications of wear were 4-observedh lower on the assem under Bank 5 CEAs during Core I at elevations ._

inches fromcorresponding the t CEA Bank'S was also inserted,- _,

insertion position. _

time (s50-60%)

top of the fuel assembly during much of Core -

II operating inches. The whiler-the remai,nder . ,- , of the CEA banks were located atLD average u of the _e for the remaining]_ assemblies which had CEAs while the{

at the all-rods-out posi~ tion was' L _I.

for a single guide tube

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coil  ;

which corresponded to an f

The maximum measured"

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(AssemblyC232

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corner) was'~ ~ probe I ~ -hobe. The#L J hich area loss of as measdred with thF _

f a i data indicates that no wear openings were observed for gu '

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lessthan[

foilsignalof These data indicate that the correlation be-have a - _

area loss, of less %than( ,3and wear magnitude in Maine Yankee tween coil Ti plants (References 1 and 2).

to that noted at other C t-II-2 t

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v REIN'CESp f

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Operation With bbdified Guide Tubes",

'. 1. "St. Lucic Unit I Reactor CIN-90(F)-P, dated April 21, 1978.

s 2.

St. Lucie Unit I Peactor Operation With Modified CEA Guide Tub 18, 1978.

Amendment 1-P to CEN-90(F)-P, dated bby 4

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TABill 11-1

v. - }&lNE YANniE EDDY CUlUUNT TESTING No. of Guide hibes Tested _

'. For __

Type Test ._

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iv Sec core maps L.

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• Dundles A030, A068, A059, listed under this category -

I for special considerations.

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i, MAINIIN YA. LT.l! A21Mll11Al. F.1)DY CUnitrJJ1' TI5I' 1)ATA_

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Axial Wall Wall 1, Arca Core Position Of (mils)_ Lost _

Bwidic Guido Residence (3) Indication *f

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Tube

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• • Only the axiaf location of maximum wear

(*) - Renidence Cycle In Coro is listed.

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Fttino Yankee Azimuthal !!ddy Current Test Data - Coittinued Min. Avg.

Axial Wall '4 , Arca l'osition Of Wall Lost _

Guide Core (mils)_ (mils)_

13undic ltesidence(q_ Indication __

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Min. Avn.

Axial Wall Wall t,Arca Core Position of (mils)_ b,s t Ikuidic Guide indication __ (milsl No. _ _

Tube _ Itesidence(#)_ -

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Axial Min. '. Avg .

Position of Wall Wall  %, Area i Bundle' Guide Core fio. Tube Residence (,) _,

Indication -(mils) jmils) ,

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Continued -!

' Mainc Y:uikee A::imuthal liidy Current Test Data .

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• Axial Wall W311 Arca

Of Bundic .Guido Core l}3j. t;on- .

(milsl (milsl }.gst itesidence(*)___ - ,

go, ___ Tube _ _ _ _

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Mainc Y;utkee A:.imuthal !!ddy Current Test 1)ata - tontinued ,

Min. Avg.

Axial Position of Wall f,;Arca Bundic Guide Core p) Indication _ (mt s, _

No. Tube _ Residence _ _ _ ,

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niinc Yankcc Azimuthal 1:ddy Current TcSt Data - Continue Axigl U, A[i('i r t, Area (inil s], Ipst _

Guide. Core gjt[, jg 1kindic Tube pesiden-(*) ~

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ht\1 N11 Y N $ 1:11 0:YCI.l! I 1111:1, A!;Sl?ll',1,Y CO 't:. tiX:ATION'i

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lbfE: A030 was located tutdcr a rep,ulating. Cl% ban k- ,

Cycic.1A.

Averar,c of Cycle 1 bundles - .

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1A.

Average of Cycle 1 and 1A bundles -

' 4....,....,. ntNnnt er r.uide tubes only (No ineasurementr. taken on center r,ut.

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}&lN11 YN33lij,fXCl.li 1 A_

- }U11L ASSlititLY Coni; LTATIOM AN1) AVFRAGil:_

(COIL DATA) .

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withdraim CI% durint, Cycic 1.

r located tmider regulatinn Ct'As during Cycle 1.

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, FIGUlUI11-4 gina; YANKE!! CYCL.li Il

}ylil, ASSIMl:1.Yjl'1 IPCNE10NS -

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TION OF'CUIDE TU3ES 0.6

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(( ][ COIL '.'ALUES sss Tnst ~1 0.5 0.4 0.3 s

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W 5.0 6.0 7.0 1.0 2.0 3.0 4.0 0 _

, COIL ,_

GUIDE TUBE MAXIMI r. ,

] Coil Data:

FIGURE II-6 Cumulative Frequency Distributions of Guide Tube (Core 1), C (Cores I & IA)7and D (Cor Maine Yankee Fuel Batches A ._ _..

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SECT 1011 III l

RESOLUT10ft - Gul0E TUCE SLEEVIflG l l

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Resolution Gui_de_ Tube Sicevina ,

III.

A. Description i

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J ily in The CEA guide tubes were found to contain CEAs when worn areas pr

'a region corresponding to theDuelocation to the CEAs ofbeing the tips of the withdrawn l inserted an additional [

) inches for the last few months d of St. tucie I, Cycle 1, some secondary wear indications were

] inches below the on St. Lucie I guide tubes approximately [

Similarly, the CEAs in Maine Yankee CEA's withdrawn position.

] inches in January of 1978, and wereinsertedanadditional[ ide tubes the presence of secondary wear locations in M may be expected. Wear, to a lesser extent, was also found one side of a guide tube. Generally, the post on the I.D. of the upper end fitting posts.

wear was displaced in azimuth from the guide tube wear.

i t The guide tube wear was caused by the CEA i d by poison rod the tube in an alternating, circumferential motion as determ n both metallographic examination of worn guide The tubes andl measurement of CEA motion in an out-of-pile hot drloop test. i reason for the CEA motion is complex and is not yet clearly The complexity is seen by the fact that the wearblyvaries stood.

from no wear to significant wear in guide tubes batch.within a fu as well as from fuel assembly to fuel assembly and batch to B. Prevention of Further Hear

• is i- , Prevention or substantial mitigation of further guide tube w accomplished by means of a sleeve which is located in th f- } inches of the guide tube. post region as show The sleeve is of slightly cold-worked type The sleeve 301 stainless chrome plated on I.D. and on the upper [ ] of the 0.0.

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III-1

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y%-,- e-m-=+--s' r7

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} which provides is showri in figure III.B.2 an d has an 0.D. of [

for a[ } mil minimum diametral clearance with the CEA guide jtube.

) with chrome plating and was Thenominalwallthicknessis[-

chosen on the basis that it would not significantly increase the\

The diametral clearance between the sleeve maximum scram time.

and the CEA,[ -),isadequateforfreemovementoftheCEArods.

The[ ] minimum thick I.D. chrome plating provides superior resistance to wear without the risk of preferentially wearing the Inconel 625 cladding. .

In order to prevent the sleeve from moving in the guide tube mder flow loads or due to movement of the CEA rods, a short region slightly above the lower end of the sleeve c or sleeves is expanded that radially so that the guide tube is permanently expanded.

will be installed in worn guide tubes, the lower [] inches of the sleeve is also expanded outward so that the 0.D. of the sleeve a For sleeves the I.D. of the guide tube take contact at temperature.

that will be installed in unworn guide tubes, the lower [] inches be expanded.

This expansion improves the heat flow from the CEA rods to the coolant outside the guide tubes.

In order to be certain of the magnitude of the sleeve expansion, a (1) selection and qualification program was perforned as follows:

irradiation testing of highly irradiation damage resistant polyethe clastomer to expand the sleeve; (2) determination of the proper elastomer geometry and durometer hardness; (3) a check of the variation in pressure required to expand a sleeve as a result.of

durometer tolerance and time; (4) determination of the difference in pressure required to. expand sleeves in unirradiated an guide tubes using the tool design that will be used in the fie All sleeve' expanding tools have a built-in positive hardstop to prevent inadvertent over expansion of the sleeves.

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Control over the expanding operations is provided in three ways:

i.

,s ii.

iii.

7. .

.a C.

Functional Performance of Fuel Assembly _

j

] types of vents are The sleeves, contain a series of vents. [

cmployed:

The deleted portion of this aragraph contains information about the number of types, size, and location of _ vonts.

,~

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~~

' The bottom ends of the sleeves are chamfered on The chanfer, plus the expansion of the sleeve in this the I.D.

region, ensures that there are no sharp edges that could contact i the CEA finger and cause wear.

i .

1

- III- 3  :

- . . =

. 1 The upper end of the sleeves are conically shaped to fit the contour of the upper end fitting posts. Since the conical .

section is not connected to the post, the stainless steel sleeve I The differential is free to expand under heat up and cool down. I

. i irradiation growth between the guide tube and sleeve results in I

~

acceptably low stresses in the guide tube and sleeve for end-of- l At operating conditions, there life cold shutdown conditions.

1s no significant stress due to this effect.

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-l , .l , ,

. . \, ,

• ~ . .. - .

A. ' !jeEi/anical litearity with Slejles,

1. Analytical Model . ,

The capability of the worn guide tubes to sustain the various operational loads depends. on the cross sectional propl the worn section and the benefit derived frcm the steel sleeve. -The wear reduces the cross sectio ,

the guide tube, but, due to the aspr. metrical nature of the wea I also changes th,e moment of inertia, location of the neutral

} axis, and the distance frem the neutral axis to the extreme ~

The added stiffness in the worn region, due to the fiber (c).

presence of the stainless steel sleeve, These isproperties accounted fo

~

~

cross sectional properties of the worn region.

must be calculated prior to the determination of the load carr ing capability of the worn sections of guide tubes.

The cross shetional properties of the worn guide tubes are

based on eddy. current test readings of the remaining cross The calculational procedure section and/or wall thickness.

assumes the wall thickness varies linearly with measured data points. Knowing the remaining wall thickness as a ' function of angle, a numerical sun: nation technique-employs one degree increments, determines the '

remaining cross sectional area and the minimum IV-1

. n . , , . ,n .-m . . , , w

i The numerical summation

- .. moment of inertia of the worn section.

l technique also determines the distance fr

?'

• the extreme fiber. .

steci sleeve are determined using standard (theequations for

' f

- i 1 moment of inertia, and distance from the neutral axis All cross sectional sleeve centerline) to the extreme fiber. f s

properties needed to evaluate the load carrying

~

.' capa sleeved, worn guide tubes can now be determined.

The operational loads on guide tubes consist l of axia and bending moments (due to lateral deflection of the fu assembly).

The analysis method accounts for the asyx.etrical wear and the stainless steel sleeve in the following man

a. Axial Str'ess -

. The stainless steel sleeve, because of the manner sta11ation, does not affect theTherefore, primary theand

' axialmembr p in the worn region of the guide tube.

stress is determined simply by axial load divided by a where the area corresponds to the remaining guide

- The axial stress in the worn '

area in the region of wear.

.. section, compared to the unworn section is there

~

by the following expression:

Area of Unworn Section

, , unworn x Area or Worn Section

' worn 1 .

• . b. Induced Bendino Moment. .

Any asymmetrical wear of the guide tube s

i. '

. axis of the worn section off the unworn guide tu line.

The shif t of the neutral axis causes a pure i

'. load to induce bending moments in the worn Lateral deflection of the guide tube in respo

<O 2

(' .

8 IV-2

d mparable deficction in the stainless

, jnoments pro uces coSince the presence of the sleeve will re-steel sleeve. .

ide tube stresses will

. duce the guide tube deflection, gu The magni- '

also be reduced by the presence of the siceve.

tude of the induced bending moment, and the pro depends the moment carried by the worn Zircaioy guide li tube,

' upon the relative cross sectional properties and m of elasticity of the worn guide dtube and the stainless The sleeve is con-

- .. steel sleeve, as wel'1 as ihe axial loa . b

, strained to deflect approximately as the worn guide tu Since the sleeve and the worn section th the same radius of curvature, the followingin expressi 4

can be derived for the relationship between the ratren in the stainless steel

, the worn section and the moment - .

sleeve:

, (EI) Worn Section Moment Horn Section _ (EI)' Sleeve Moment Sleeve l

3 By satisfying boundary conditions of lateral defl and angular rotation at the interfaces of the worn a unworn scctions, (see Figure IV.A.1), the d induced moments in the worn (and The bending therefore stress in th unworn sections can be determined. ltd associated with the induced bending moments is c using the conventional a = Mc/I equation.

4 Lateral Deflection Bendina Ibment_

c.

- Conditions which cause lateral deflect ide sembly give rise to bending moments in the ind The applied bending moment in the sleeved, wor

,^ - tubes. h

1. • guide tube region is divided betweenbthe ve. slee worn guide tube, according to the expression show

~ .

O IV'3

COMBUS1'10N ENG!NEElilMG, INC.

o I ,

P e M) d P

Modeling of

-F 4 .-

///// Siceve Shown

in Phantom a

"' l

% L) .

g

- 3p Offset of - -

' l ticutral aI Axes (e) ,

-r- ]F .

l Y " h"P g?

1

~

j I

l L

2 mg  :

Y~F e

P

,f j 7

~"~

Ifoutral Axis "2 m ,P of Ilorn J f' i gq O , ]

Section ,

l

/ '

Unworn Guide Tube / 3 - .

Centerline

, ' M 2

N1-FxL) 3 14 3

=

Pxe-M2

=

M 4 M3+FxL2 l

" U 1 .

- (M4 zirc + " sleeve}

=

F1 5 P.x e - M4 F1 6 ." US~fXb3 l l

r -

e

///// .

F~

P

'UM T .

6 i

. . p free Body Diagram Loading Condition .

1 l ,

() -

Af!ALYTICAL t'0Dr.LlllG OF WORil GUIDE TUP,ES UITil STAlflL1 flGURE IV. A.1 ,

SLEEVE UNDER AX1AL LOADS l .

IV-4 ,

l

I l

These; bending moments are handicd'the same as the induce bending moments for calculating the resultant stress.

. Since the applied l namely the conventional om Mc/I equation.

• 4' '

bending moment varies with axial . position, the magnitude of the bending moment is consistent with the elevation of

' s

. 'the wear. l s .

The state of stress in the sleeved worn guide tube section -

can be evaluated by combining the axial stress, the induced I

' . bending stress, and the bending stress due to lateral de- l flection of the fuel assembly. The stress level in the l

~

stainless steel sleeve is determined by combinir.g the in-

'duced bending stress and the bending stress due to lateral The capability of the sleeved worn guide tube

- deflection.

to sustain the various operational loads can be determined by comparing the stresses in the worn guide tube section and in the sleeve to their appropriate allowables.

p ....__... .

l' 1 ,. , _ , ,_, ._

a

• e e #

d

~

- l G

e

. e

• l

• l O

G '. 8 e

• 3 . g 1

, , l

, .s I

., ,. j W

(.,

4

. G '

IV-5 1

. -. - . , . - , - . . . _ . . , ,1

COMBUSTION ENGINEERING, INC.

2.. Mechanical Load Reauirements

- The 'various mechanical loads to which fu s -

having worn guide tubes will be or may be subjec .

' .. . as foilows: . ,

a. fuel Bundle liftino loads - 1700 lbs The actual fuel assembly weight is 1275 (Note:

lbs. However, fuel handling equipment is load limited to 1700 lbs, so that it is possible for loads of this magnitude to'be applied during fuel handling).

b. Fuci Assembiv Holddown l assembly provides

. The upper end fitting of the fue spring loaded holddown to restrain the assembly The maximum from lif t off due to hydraulic forces. i

)* .

magnitude of this force is [ ] pounds at operat rig

. temperature and [ ] pounds at co ld shutdown conditions.

c. CEA scram Deceleration For those fuel assemblies which are lo locations, there will be an additional and very short term transient load associated Most wit CEA deceleration following a scram stroke.

of the energy of the decending CEA is' absorbed the hydraulic buf fer, and an additional amount The is absorbed by conpression of the CEA spider sp small amount of energy 'which remains The is ab axial compression of the fuel assembly [ structure.]

,' .a resultant axial load on the fuel assembly is t ,

d. Seir.mic Excitation loads

• The effect of the postulated Safe Shutdown i Ea quake is to produceThis significant lateral deflect deflection, in turn,

.? of the fuel assemblics.

i .

gives rise to axial loads and bending moments in the

, individual guide tubes (except for the center guide

_ tube, which, by virtue of its position on the neutral

" axis of the assembly, carries a bending moment but essentially no axial load).

s The following range of loads is produced on individual guide tubes.

] pounds

1. Axial Load: ['

Bending Mament: [ ] inch-pounds 2.

3. Criteria for Allowable Loads _ c:

Stress intensities produced in the wornconditions d loading sections of the guid

, tubes by the various expected and postulate are compared with allowable levels appropriate ito the tempe at which the load is applied, the nature of the worn ified cross-se at which the load is applied, and whether the loading is clas as .the result of a normal operating or accident condition.

l 4

6 0

l w

. 8 IV-7

COMGUSTION ENGINEERING, INC, ,

The specific allowable stress intensities are discussed -

.below: .

l a.

!{onnal Ooeration: -

' or 1/3 " ultimate Pg < 2/3 yield g + PB <" yield or 1/2 oultimate P

for temperatures associated with operating conditions, the numerical values are as follows:

P g<(. '}

Pg+P8 b -) - l D- Fuel llandling_

b.

A fracture mechanics analysis was c.onducted as follo 1.

The analysis was carried out by modeling the most severe guide tube wear geometry in the MARC finite/

The guide tube cross-section

, element analysis method.

was determined from azimuthal eddy current exa and was assumed to taper to an unworntion. cross sec

[ .]inchesabovetheminimumareacross-sec ii.

The model assumes the presence of circumfe extending from edges of the remairiing cross-se

' ] inches.

where the cross-section thickness exc iii.. The evaluation calculates stress inte roots of the assumed cracks which are then co (m

y 1 .

e L ,9 IV-8 l

- ._ " +4 i

COMBUSTlUN L. tut n.um ~, .. . .

' the appropriate properties of irradiated Zircaloy

• l "

• .taking account of the adverse effect which could be present in a very severely worn guide tube and also

' J

• ' taking into account the fact that much of this hydrogendling

.would be precipitated es hydride phase at fuel han ,

temperatures rather than dissolved as it would be at operating temperatures. -

'iv, 'The axial load vfhich is applied is equal to 1.5 times the submerged weight of a fuel assembly as a means of allowing for uneven lifting forces arising out of

' machine operation or intermittent drag from adjac2nt

.' I fuel assemblies.

Using the analysis method described above, it was con that the margin against propagation of the assumed cracks would be indesirably small in any guide tube in which the extent of wear was such that lifting loads produced a pri-mary stress intensity in excess of [

] . This value is less than would be derived from application of the for-mula in Part a.to irradiated properties at fuel handling temperatures and should be considered Al asthouch the limiting terion for stresses induced during fuel handling.

i is considered to

, the analysis which led to this conclus on be co.nservative, it has been considered advisable to recom-mend that those few assemblies which contain guide tube to this level of severity not be handled without reinforce-ment until such time as improved understanding of the  ;

and properties of the worn areas may show precautiol .

, , , l

• - . unnecessary.

c. Allowable Seisnic loads _ ~

The elements of this evaluatien are simil It involved the fuel handling analysis discussed above.

. modeling of actual wear cross sections in the MAR

.. element analysis method and the assumntion of rela l' ' O- severe circumferential cracks in the most highly st The predicted seismic excit? tion region of the wo'rn area.

...n

E COMCUGTION ENGINELmnu, my, loads were then imposed and a determination, based on fracture mechanics considerations, was made of whethe riodic occurrence of the peak scismic excitation f loads

,f would be sufficient to cause significant propaoation o

• the assumed cracks. .

The results of this analysis indicate that guide tubes with wear patterns which result in predicted ,

l'may stress iriten sities for the peak seismic load exceedino [

be subject to substantial crack propagation during the postulated SSE. .

d. For CEA Scram Loads:

Pg < 2/3 yield '

Pg 4PB # # yield The corresponding numerical values are:

) .

.p <[ -]-

~

Pg+Pg<[ T .. ~

e, forLOCALoads:

There are no specific guide tube stress criteria for This is b5cause the acceptability oflish- the fuel LOCA loads.

assembly response to LOCA loads is determined b!

ing whether the fuel rods are maintained in a co >

, The existence of such an array is dependent upon bility of the spacer grids to withstand the predicte

,, ' lateral impact loads associated with the LOCA nificant deformation. ,

In addition, the absence of specific stress criter guide tubes under LOCA loads is justified because U' .

analysis for the core response to large break L IV-10

. t y . ,,r , . . - , s v-,, ,-r--y  % .a+.< q. ~

takes no credit for CEA insertion during any part of the postulated LOCA.

The allowabic stress criteria presented above are based on the minimum properties of annealed Zircaloy-4 which has been irradiate 21 flVT (>l Mev) which corresponds to the

• to a fluence of 0.23 x 10

' minimum expected neutron fluence sustained at This the elevation value of the observed guide tube wear during Maine Yankee, Cycle 3.

reflects the results of a fast fluence determination made on section of Millstone II guide tube using the disintegration rate of Maganese-54, and includes a factor to reflect the fact that Maine Yankee EOC3 burnup is somewhat less than the Millstone value.

As is shc in on Figures II.C-3 and II.C-4 of Cell-82-P, the properties of Zircaloy in this condition at normal operating temperatures arc as follows:

'~' ~

Yield Stress = [.i _ _ f]

Ultimate Stress

=

[ _

.]

'The specific accounting for the effect of fast neutron fluence on the capability of the worn guide tubes to sustain operational load is based on the observat' ion that the wear mechanism is capable producing significant alteration in the guide tube ross section only af ter thousands of hour's of operation with the CEA 'in Since the wear of the guide ttbe I.D. and the withdrawn position.

irradiation of the guide tube material occur simultanecusly, the guide tubc properties at areas of significant wear will corre It is, therefore, appropriate to to those of irradiated Zircaloy.

base the evaluation of the load carrying capability of the worn ^

~

areas in guide tubes on the actual properties of the material in these areas.

Since the stainless steel sleeve carries a portion of the total l the following additional stress intensity criteria are required fo the sleeve: .

Pg < 2/3 oyield r 1/3 oul tima te P. , + P n <

ov icid

O

. COMBUSTION ENGINEEiilMG, INC.

. o At room t,emperature, the correspondinq numerical value s .

w

.- stainless steel sleeve are: -

g < 20,000 psi P

~. . .

~

~

Pg+PD < 30,000 psi * .

~

At operating temperature, the corresponding numerica the stainless steel sleeve are:

- P g < 12',133 psi

.P g + Pg ,< 18,200 psi *

~

O '. '

o 22.

• A$ lie Pressure Vessel Code,Section III, Appendix 1O I- -

ly-12

t f

f

4. Analysis Results

~.,

The effect of the various expected and postulated loading conditions on the wear sleeves and/or guide dtubes stresses 2

\

have been evaluated using the methods and criteria discusse (

• t The results of these analyses are presented below:

• above.

a. Unsleeved Guide Tubes All worn guide tube cross-sections obtained IA from 'the ,

azimuthal coil ECT examination The results of thesediscussed in S of this report have been analyzed.

individual guide tube evaluations, in the ilform of the predicted resultant stress intensities in the mater a remaining at the worn cross-section, are presented in Table IV.A.1 of this report or in Table III.A.2 of CEN-82 P as modified by Section IV.C.2 of Amendment 2

~

b. Sleeved Guide Tubes All worn guide tubes analyzed in the above section were also analyzed to determine the effect of an installed Since the effect is sleeve on the predicted stresses.

always to reduce the predicted stress in the guide tubes and since the resultant stresses in the sleeve are highest in guide tubes exhibiting most severe wear, the results presented in Table IV.A.2 are only for those five Maine Yankee guide tubes which exhibited the hig stresses in the unsiceved condition.

The analyses for Tables IV.A.1 and IV.'A.2 of this rep to Cell-82 P, include an adjustment Section IV.C.2 of Amendment r- 217 eddy current data. The azi-applied to the results of the _

l is is muthal ECT data adjustment used This in the revised stress an conservatism or based on a systematic ECT data conservatism.

IV-13

1 TABLE TV.A.1 Maine Yankee Unsleeved Guide Tube Stress Summary (KSI)_ i v

Loading Conditions \'

fuel Bundle Guide (1)(2) SSE Tube Normal Scram Assembly Lifting s Location

'. Serial Number

-1,6 -6.2 4.0/-6.6 S.6 1

-11.2 7.4/-12.1 10.1 -2.9 A002 2

-0.9 -3.5 2.3/-3.7 3.1 3

-2.0 -7.7 4.6/-7.8 4 6.9 _

-7.8 5.1/ - 8. 3 7.0 -2.0 1

-10.1 6.7/-10.9 9.1 -2.6 A013 2

-12.2 8.2/-13.3 11.1 -3.1 3

-6.2 4.1/-6.7 5.6 -1.6

'4 _

-11.4 7.6/-12.3 10.3 -2.9 1

-13.3 8.9/-14.5 12.0 -3.4 2 4.6/-7.5 A014 -1.8 -7.0

m. 6.3 3

-13.7 9.3/-15.0 12.4 -3.5 4

-12.1 8.1/-13.1 11.0 -3.1 1

-5.3 3.4/-5.6 4.8 -1.3 A019 2

-3.0 -11.7 7.6/-12.5 10.5 3

-1.2 -4.7 3.0/-5.0 4

4.3 _

(1)was Nofor azimuthal data was taken on center lifting information and the center guide tube is assumed t guide h e tubes si none of the load for lif ting.

(2) The indicated guide tube location, with respect to 2 3

the fuel assembly's serial Serial Number

• number, is as follows: xg x

. x X

X v

X 4

1 i

IV-14

Maine Yankee t EnsicevedGuideTubeStressSummary(KSI)(cont)_

Guide O)(2) L adin9 Conditions 1 Bundle SSE j Tube flormal Scram --- ,

Assembly Lifting Location 3.5/-5.7

. Serial fiumber -1.4 -5.3 ,t 4.8 10.1/-16.2 1

-3.8 -14.8 s

2 13.4 13.9/-21.7

' A020 -4.8 -18.9 3 17.1 5.4/-8.7

-2.1 -8.1 4

7.3

-4.5 2.9/-4.7 4.0 -1.1 1 -13.5 8.9/-14.5 12.2 -3.4 2 -19.3 13.6/-21.6 A021 17.4 -4.9 3 -7.9 5.2/-8.4 7.1 -2.0 _

4

-3,0 -11.9 7.9/-12.9 1- 10.8 23.5/-34.8

-7.0 -27.3 2

24.7 3.4/-5.6 A026 -1.3 -5.3 3

4.8 9.8/-16.1

-3.9 -15.1 4 13.7 _

-4.6 3.0/-4.9 4.1 -1.2  ;

1 -3.5 2.3/-3.7 3.1 -0.9 2 -6.5 4.2/-6.9 ,

A027 5.8 -1.6 3 -19.1 13.2/-21.1 17.3 -4.9 _

4

-36.6 29.8/-45.0 33.1 -9.3 1 -12.6 8.1/-13.3 11.4 -3.2 2 -10.3 6.7/-11.0 A028 9.3 -2.6 3 -6.0 3.7/-6.2 5.4 -1.5 -

4

-7.2 4.7/-7.7 6.5 -1.8 1 -9.8 6.4/-10.5 8.8 -2.5 2 -13.3 8.8/-14.3 A033 12.0 -3.4

. 3 -10.3 6.9/-11.1

. 9.4 -2.6 --

4

-13.1 8.9/-14.3 11.8 -3.3 1, -10.8 7.1/-11.6 9,8 -2.8 2 -13.4 9.0/-14.6 l

• A034 12.1 -3.4 3 -7.1 4.5/-7.4 6.4 -1.8 __

4 t te I f;

~2------____ _ _ _ _ _ _ _ _ _

I l

N ss sumjr ary__QiS.d_.IC9"M- -

i

• nsleeved Guide Tube Str1 _

l O M2)

Loading Conditions \

' Guide SSE Fuci Bundle Tube flormal Scram -

Assembly Lifting

,'. Scrial flumber Location 3.3/-5.3

-1.3 -5.0 4.6 10.3/-16.4 1

-3.8 -14.9 2

13.5

-15.1 10.1/-16.3 f A049 13.6 -3.8 3- -5.3 3.4/-5.6 4.8 -1.4 -

4

-8.0 4.9/-8.2 7.2 -2.0 j 1

-12.7 8.5/-13.8 11.5 -3.3 l 2 -6.6 4.3/-7.1 A056 6.0 -1.7 3 -3.8 2.5/-4.0 3.4 -1.0 _

4-

-13.7 9.3/-14.9 12.4 -3.5 1 -4.0 2.6/-4.2 3.6 -1.0 2 -6.2 3.9/-6.5 A063 5.6 -1.6 10.3/-16.6 3 -15.2 13.7 -3.9 _

4

-7.4 4.8/-7.8 6.7 -1.9 1 -3.5 2.3/-3.7 3.1 -0.9 2 -12.2 8.2/-13.3 A064 11.0 -3.1 3 -9.3 6.1/-10.0 8.4 -2.4 4

-22.6 17.8/-27.2 20.4 -5.8

' 1

-14.3 9.7/-15.7

, -[ a,. -3.7 2

13.0 9.6/-15.6 A065 -3.7 -14.4 3

13.0 2.3/-3.8

-0.9 -3.5 4

3.2 _

-9.3 6.1/-9.9 8.4 -2.4 1 -11.7 7.7/-12.5

', 10.6 -3.0 2 -7.0 4.6/-7.6 C212 6.4 -1.8 3 -13.3 9.0/-14.5 12.1

-3.4 ~

4 '

l

~-

1 l IV-16

I f

gaineYankee_

s Jnsleeved Guide Tube Stress Summary (l'SI) (contl Loading Conditions Guide (I)I2) 4 Fuel Bundle Tube Scram SSE

• Assembly Lifting Normal _

Location 2.3/-3.7 Serial Number -3.5 3.1 -0.9 1

-12.8 8.6/-13.9 11.6 -3.3 2 -11.5 7.5/-12.3 C220 10.4 -2.9 3

-10.1 6.7/-10.9 9.1 -2.6 . . -

4

-12.6 8.4/-13.7 11'.4 -3.2 8.8/-14.3 1

-3.4 -13.3 12.0 2 -18.3 12.8/-20.4 C221 16.5 -4.7 3 -7.7 4.8/-8.0 7.0 -2.0 _

i 4

l

-7.2 4.7/-7.6 6.5 -1. 8 1

-13.9 9.1/-14.9 l 12.5 -3.5 2

-3.5 2.3/-3,8 s, C226 3.2 -0.9 3

-2,2 -8.7 5.7/-9.3 4

7.9

-8.1 5.3/-8.7 7.3 -2.1 1

-3.5 2.3/-3.7 3.1 -0.9 2 -3.5 2.3/-3.7 EF45 3.1 -0.9

'3 -6.6 4.5/-7.2

-1.7 4

6.0

-16.9 11.9/-18.9 15.3 -4.3 1

-11.4 7.4/-12.1 10.3 -2.9 2 -9.7 6.4/-10.4 EF5H 8.7 -2.5 3 -9.6 6.3/-10.3 8.7 -2.5 _

4 O

5 v

IV-17 t

(KST)

.. [

Eff E.CT.Of UCAlt 0l1 Gj!,ioi. TUP.C STPCSSE.S,_

(SELECTED 00100

• TuiiCS) i_..

Fuel Assembly .

LoadingC$ndiIion Serial Ilumber l

and Scram SSE Lif ting flormal

• Condition o a ion

-27.3 23.5/-34.8

-7.0 24.7 -14.6 5.3/-11.3 Guide Tube as is 13 . .g

-3.7

-13.7 8.6/-14.3 Guide Tube Siceved 3 -3.5 A025IlE \

Siceve Only -- _

-36.6 29.8/-45.0 l

-9.3 33 1 7.5/-15.3 t Guide Tube as is -4.8 -18.9 l

1

-13.5 8.4/-14.0 Guide Tube Siceved *2 3.5 A028 SW

.Siceve Only _

-22.6 17.8/-27 2 s-  : S e8

,20.4 -12.6 4'.9/ -10.2 Guide Tube as is -3.2 11.4 8:0/-13.1 Guide Tube Sleeved -3.1 -12.3 l A065 SW 11.1~ __

Sleeve Only

% -26.9 21.8/-32.9 24.3 -6.9

( 5.8/-12.5 Guide Tube as is -4.1 -16.2 14.6

-11.6 8.1/-12.9 C202 SW Guide Tube Sleeved -3.0 10.5 _

Sleeve Only

-22.6 19.0/-28.3 20 4

-5.8

-14.7 5.2/:11.4 Guide Tube as is 3- -3.8 l d 7.6/-11.6 Guide Tube Sleeve -24 -9.5 C232 SW 8.6 j Sleeve Only -

l

• llot iloiddown , ,

, O e b

. 4 1

~ .

l

. j IV-18 ,,

I

h t are systematic bias caused an overestimation in wear regions l steep-sided'in the circumferential direction; i.e.,This is related ,

l to the physical dimensions of the coil field d the thinnest

" and the fact that the coil response is weighted towarTh '

in the direction wall in the sector scanned.-

wall sector reading is displaced by approximately imuthal away from the minimum wall region, thus h eexaggerating is no the extent of the wear opening (or minimum wall region when t opening).

imum This bias was confirmed by hot cell metallography guide tubes. Tte of the m .

wear regions of two Millstone-II Assembly, h the cor- l resulting wall thickness variations In both cases, were compared wit responding azimuthal ECT data. ~

~~'

Further comparison of the wall

~..~ .

atively /

thickness data snowed that the ECT results indee The bias also overestimated the azimuthal extent of maximum d simu-c- wear.

was evident in measurements The directly measured areaon lossan was' ECT . calibr lating steep-sided wear.

. .. _ t

~

tism This adjustment has been selected Theso that sufficient conse conservatism in the input " remaining wall" is maintained. table of the applied adjustment is demonstrated l ECT area in the followin which compares the above directly measured and origina loss values with those obtained with the adjustment.

Per.cnt Area tois Original Adjusted

. Azimuthal Azimuthal o

' Direct ECT ECT _

Tube Measurement.

' '* }teasured . - . .

e 9

te

,4 .

e

. J 1: . _

5. . Additional Mechanical Considerations for Sleeved Gui v The stress analysis results presented above include all primary <

However, the stresses to which the sleeves may be subjected. 's,

.~.

property differences between stainless steel and Zircaloy give  !

rise to suostantial secondary stresses which have also been

'. The following specific concerns, arising out of the examined.

material differences and other mechanical considerations, are discussed in detail in Section IV.A.5 of CEN-90(F)-P.

I

a. Differential Thermal Expansion

b. Differential Irradiation Induced Growth ,

c. Induced Strain From Diametral Expansion

d. Effects on Dynamic Tube Response

e. ratigue Endurance Due to the similarities of components and operating conditions between Maine Yankee and St. Lucie 1, the discussions and con-clusions presented in the referenced section of CEN-90(F)-P are applicable to Maine Yankee sleeved guide tubes.

l t

i

]'- . .

~

I . '

i IV-20

'\. .

i ,

=v . , . , - -

o s._ ,+A s

B. Analyses v

Seismic AnA vr 5 is shown in 1 '1. lies The detailed core model used in the analyse l assemblies and

., Figure IV.0-1.

including gaps and impact elements between shroud. fue between the peripheral fuel assemblies i since itand is thethe core The 15 assembly row model was chosen for analys s longest row with CEAs positioned in the peripherans previous analyses have shown maximum fuel respoT peripheral assemblies of the longestflect row. test data stiffness parameters used in these analyses rei s as a re showing lower fuel assembly natural frequenc e grid spring relaxation.

f the model representin:

The s'eismic excitation applied to the nodes o s the acc the core support and fuel alignment plates wa for the lim

'~'

history response of the reactor vessel flang t guide tube operating plant.

analyses which have shown it to yield the largesSinc stress for any of thd 14x14 assemblyponse plants.relative to appreciable amplification of the core s used plates directly. res the flange, the flange response time history wa In the first analysis it was Two analyses were performed. blies were f the assumed intact.

all guide tubes in the perip i

guide tubes in the wear area arofregion,,obtainct the periphe h completely severed. h corresponding to peak bending moments i at t e we the seismic from the first analysis, were utilized to determ n loads on individual guide tubes.

ere reported in Section IV.A of this report.

. 1 1f.

.a IV-21

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' '3 pypassFlow/CoreFlow d on an assumed design value be at Design thermal margin calculations are baseFor Main j of bypass flow.

least 2.9% of the primary coolant system flow.

• - /

i alculations for the Maine

-The validity of present design thermal value ofnbypass i marg c flow

[ Yankee reactor was assessed by comparing the des gndimensf ed guide tubes (2.9%) with bypass flow calculated using as l reactor.

were considered. '

l }oftheguidetubes The basis for the analysis is that during each cyc e,ings obser in CEA. locations develop the maximum l 1size wear open observations for value is based on Millstone 2, Cyc e Further, it stone 2. The .

ide tube wear.

the{ ] assemblies' having the isassumedthat[

mostin the A locations serious pre- gu]o Maine Yankee, v

locations during previous cyclesopenings. and are in non-CE j sent cycle have developed the maximum size wear l assemblies' Cycle 4 will have sleeved guide tubes in all fueith signific I at CEA locations and in otherhichfuel allows the guide tubes assemblies w The sleeves cover the wear openings in a manner wTherefore to be considered as hydraulically intact.

expected in Cycle 4. .

IV.B.1 t!e believe that The results of the analysis are l listed in Tableinsignificantly g the calculated bypass flow has been on yFor cycle 4 the calculated design thermal margin is l , design value during previous cycles.

j .

is less than the design value and therefore the preserved.

e I

IV-23

_ ._ _ _ . _ .. _ _ . _ . _ . ~ .. _ _ .--

g SUNRY OF BYPASS FLOW COND( DNS FOR MAINECore- (YA*;KEE Total -

. Size of Wear Opening  :

Byoass Flow , ,

~ Condition of in Guide Tubes e Time in Core Guide Tubes l Basis for Bypass Flew Life _ 2.9% .

-l Condi tion _ _

Zero , _

All Intact r 1'

l. Set Point Design Basis Zero . '

Intact .

Start of First "

~

~

i .--

~-

2. Reactor As-Built Cycle ~

Maximum Observed -

Condition ' Wear Openings End of First . Size in Millstone 2 "

l, in[ JofGuide

[ .

3. Reactor As-Built Cycle Tubes in CEA ,

~

Condition locations  ;

Wear Openings Maximum Observed End of Second 'of Size in Millstone 2 -

Cycle in[

4. Reactor As-Built . Guide 'iubes Condition: ,

in CEA Locations .

(new core for Cycle 2) .

' Maximum Observed '

Wear Openings Size in Millstone 2 q End of Third 5 in[- Jof Guide .

% 5. Reactor As-Built Cycle ~ Tubes in Present .

~

Condition .

and Previous CEA '

~

Locations

. .Zero ,

. Intact (siceved.

End of Fourth' guide tubes in S. Reactor As-Built - Cycle all CEA locations i

_l Condition and in non-CEA locations, as required) 9

' e I .

g g .

5 , <

t

_ _ _ _ _ _ _ - _ _ . _ __ _ _ _ _ _ _ ____._ _ _ _ _ _ _ _ _ _ _ _ _-_____-_-_______________D

i

3. Effect on CEA Scram The effect of the presence of guide tube sleeves on the ability  !

I of the CEA to meet time requirements for CEA scram has been j

evaluated both analytically and experimentally; and the results

, l of thc:e evaluations show that the presence of the sleeves In addition, Will noc significantly increase the CEA scram time. l the capatility of each individual CEA to scram within the l required technical specification time limit is verified as a part of the standard test sequence following a refueling shutd In view of the analytical and experimental determination of the effect of guide tube sleeves on CEA scram performance, and takin l

into account the actual CEA scram testing which will be done on I all CEAs before power operation is resumed, it is concluded that the possibility that the sleeves will have a significant adverse effect on CEA scram, and that that effect would not be detected before the reactor returns to power operation, is negligibly small.

s-4 9

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IV-25

- o i Between Guide Tube & Siceve

4. . Thermal-IIydraulic C:hav or hydraulic behavior in the fluid fbetween guide tube v,

assumptions:

', .The thermal and sleeve has been examined for thd following set o -

e A water-filled gap exists between guide tube and sleeve.

a' . '

b.

The CEA rod is in line or point contact with' h the sleeve;

• thus there is a local region of the sleeve I.D. and t e CEA which is not cocied by the guide tube coolant flow. .

c.

Boiling on the stainless steel surface in the ture sleeve-to- '

guide tube gap will occur if the sleeve surface tempera.

reaches Tsat' , .

the

' The results of the thermal analyses for the water gap between sleeve and guide tube indicate that:

1.

In the unexpanded region of the sleeve boiling limiting will not occur when the linear heat rates The of the limitinaCEA rod are belo heat rates shown in Figure IV.B.2 (line A)',' tion CEA rod heat rates are represented on this figure as a func ,

i of the assembly radial peaking factor.

hn 2.

In the expanded region of the sleeve boiling will in the not occur w the rod heat rates are below the limiting heat rates shown following figure by line B. .

I e

s 9 6 V

\ .

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k. ,

[- - IV-26

- , . -, ,, , .,,.--,.n, , , . . . ene

i m uu_ .

,.__ MA i n t.

- 1 l

I i Linear CCA Rod Linear llcat Rates to Preclude Boiling in the llater Gap s .

.._.._..L....;........... l

! Between the S',ceve and Guide Tube

. . .; vs. _..m.....,

.f

' i ,

, v

.....i...__..... -

Integrated Assembly Radial Peaking Factor r - - . r.-r ----=-2.- .

1

... . 1 L___ l

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1 l t

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l l

l Fuel Assembly Udi_f_t t

f t of " sleeved" S.

An analysis was performed to determine the ef ecThe a guide tubes on f uel assembly uplif lculationai

t. procc-using design fuel assembly uplift force bcaflow due to

'; dures, making allowance for the reduced guide tu etop  !

lift force the tube.

presence o.f a sleeveh sleeves. inserted into th is increased by 10 lbs. due to the ificant. presence of t e This increase in assembly uplif t force is insign

6. Effect of SlMve Exnansion on DNBCEA guide tube Expanding the lower end cf the sleeve terior of the into the This bump produces a small circumferentialion.bump on the ex f guide tube at the axial high.

position of the expans isapproximately{

d e effect on Consideration was given to the potential h expansion. for a vers j DNB due to the flow disturbance associate i will have It was concluded that the presence of the expans on no adverse effect on margin to DNB. in References 1 and 2.

this conclusion is the results presented i d with an Those references present DUB test results obta ned r unheated rod bowed to contact adjacent the vicinity of heate or with local flow blockages (Reference pressure 2,

t the DMB location.

pWR-type rod bundles and with values of flow ra e,f and inlet temperature representative o l ower at DNB Those results showed no adverse effect t tially on bund e even for local geometry variations judged subs an

, sion. Those more severe than that associated f h with the expan flow disturbance

]

, results provide convincing evidence that t eeffect on

- due to the sleeve expansion will not have an adve margin to DNB.

~

IV-28 w%-,

PseISIgn,1gp,s.,

i y) and CE!1PD-225 Fuel and Poison Rod Bowing, CEttPD-225-P (Propr etar

1. ,

(tlonproprietary), October 1976.

Spikes or Local ,

dles , K. W.11111,

2. Effects on Critical IIcat Flux of Local llcat Flux Flow Blockage in Pressurized Water Reactor Rod Bun et al, AStiE Paper 74-WA/ilT-54, e

S e

9 4

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se e

a 6 e

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e i

IV-29 4 e e - y w

I C. Test Programs, In order to ascertain the adequacy ofsleeve the sleeving guide tube design, a num 3

%s These tests include:

of tests have been run.  ;

expansion tests at Battelle (Columbus) on a section of irradi ,

l 9

guide tube material, tensile tests of the conical and expand

'- ' 9 section of the sleeve-guide tube combination, wear tests at rea temperature, pressure and coolant chemistry conditions, tests, CEA rod insertion-withdrawal testing and a full scale fl of a 14x14 fuel assembly containing 5 sleeves, a CEA, CEA s j CEDM, and other simulated reactor internal components, , i In summary, these test results indicate that the zircaloy guide tube is amenable to sleeving, that the chrome plated sleeves incl the wear resistance to() times that of zircaloy, that i thennal will not significantly affect the mechanical integrity of the jo nt, that scram time should not be significantly affected, and that abnormal (accelerated) zircaloy corrosion will not result from 1

presence of the sleeves.

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,, . . - - , ...,-----r-r---

y, field installation of Sleeves v

A. procedural Method

%. _ Sleeves will be installed in the designated Prior to sleeving, allfuel assem

. spent fuel pool or fuel up-ending niachines. ht J

CEAs will be identified and removed from thos A crane is positioned over the will have sleeves inserted in them. Prior to insertion, all sleeves will fuel assembly to be sleeved. The sleeves are I have been quality control inspected and released. the then inserted in a sleeve tray which is located adjacent to Each of five sleeves will be removed from blythe tray work platform.

and inserted in each ofThe the five guide tubes of the fuel asse sleeves are then tamped down to with a sleeve handling tool. judged

' the appropriate height in the fuel assembly which can b relative to the top of the guide post. l After sleeves is fixed by a hardstop on the sleeve insertion the bottom too .

all five sleeves are in place, each sleeve is expanded n near s- of the sleeve into the guide tube using a sleeve / guide tu With the aid of a sleeve expansion tool, the sleeves described in sion tool.

are then expanded against the I.D.

Chapter III. h lastic of the g use expanded elastomers with fixed hardstops to provide deformation required of either the sleeve or the sleeve The fixed hardstop on each of these tools prevents guide tube. At the completion of this opera-overexpansion of the elastomer.

tion, two I.D. gauge tools are inserted the fulli length of sleeve to ensure that the proper I.D. of the sleeve t CEA has b tained and that there will be no interference with subseque notion. .

M O

e, e

4 1

t

. V-1

COMBUSTION ENGINCErslNG, IMC, B. Equipment and Personnel Guajificationt .

D Each sleeving tool that is to be sent.to a siteEach willtool be prcof te and certified prior to its shipment to the reactor site. On this used in the repair will have its own certification sheet.

sheet, a record of the following is logged:

3-

. 1. Equipment Idenfification Name .

2. Serial t! umber

- 3. Tool fianufacturing Drawing Number -

4. Tool Properly Manuf actured - Verify

' S'.

Tool h'eight (Dry)

6. . Test Requirements

7. Tool Certification - Verify Each' indivi' dual who is to perform actual sleeve repair op'erat at a site will. be trained in these operations for a minimum of tw

' days and will go through the complete operations that he w A qualified engineer wili prepare a qualification b certified for. ~

' sheet for each individual who wil1 participate in the site repair The individual will be certifed for having of the guide tubes.

'sucessfully completed the training for the operat, ions that be allowed to perform at a reactor site. .

Site Quality control _

C.

1 There will be a full-time site quality control engineer to witnes 1

The site quality control en-I- and approve all site repair effort's.

I

' gineer will sign off on all data sheets All conditions which to verify that the

• ' fuel assembly is ready for reactor operation.

do not meet quality control requirements and cannot be cor by agreed upon and approved contingency plans shall be deviation notice. Those fuel assemblies so noticed shall be unacceptabic until the condition causing the deviation notice v '

been satisfactorily resolved. ,

p 4 8 .

6 .

• U9

~ -

General Considerations D,

3 v When working over the spent fuel pool, all tools and equ  !

'be tied with a lanyard and attached to the operating All re- platform f

prevent tools from impactin'g the top of fuel assemblics. ,

pair operations will be performed with the assistance of ul

", f the

' television cameras and lights so that visual verification l o actual operations will be performed by qualified site personne .

A complete set of quality control records will lity be maintained each individual fuel assembly that is repaired and all qua ,

control records will be maintained by C-E's Muclet.r Products facturing Quality Control Department.

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VI' M emonstration Fuel' Assemblies.^ * -

. ~. , , ,

.l. -

In'troduction.

• dditio'n to the use of sleeves inserted in the CEA guid'e tub l schemes In a for against wear, Combustion Engineering has considered and teste aimed at preventing CCA vibration and thus eliminating the mecha Two dif ferent schemes , namely, [

guide tube wear.

. { .

). This has been demonstrated by testing to; -

' vibration to'a substantial degree.

- the need for guide tube sleeves. j

. f these concepts for future 14x14 .

It is planned to verify the acceptabili[ty QJ Maine Yankee Cycle 4 assemblies. d in  !

fuel by incorporating.these changes in The Figure specific assemblies involved and the concept i . .

i test  !

)

that its use will have no adverse effect on reactor performance, s data indicatesThese a high probability are modifications for therefcre producing acceptable acceptable fori use guide in ,

, characteristics.

Maine Yankee and will provide in-reactor experience to sl Descriptions of L .  !

J. cation for use in 14x14 fuel designs.)andthetestingperformedtosupport the above conclusions are given below. -

II.

Modification Descriptions. '

~ l (see Figure 2)

A. b .

o. .

l,_.

..J f

The essential design . eatures of t. . ., . ,, ..

are as follows.[ _ _

.- . ~. _ . . . .

.. --. e ,,ea ,

,,..y. '.

--*O

• _ ,

p egg ___

. p.s. e8-.

,+de

- g pe

• dbg ****.69

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g

, , . gA We M 'I '*

us..=** ~

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. '~~

"'I

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.v . .

A . .

9 .g

\4

- - - - - .~- v ., ,- ,.,v,.~ . , . , .

l.....' . .

is made from the same type of 304 stainless ' steel material as . j

" .'The [the post [tself, and it is machined to [

v i

(

. . .; y .

' 3aresuchthatall. design.

Therelativedimensionsof[

• 7' .

. original structural criteria continue to be satisfied with the new '

].

. ~

B. f

. ..__..).involvethechange The ionificantdesignmodificationsto[ .

of . . .. . ._. . _____ ___.. - - ] The speci fic [

are indicated in Figure '3 ,

, ~

as_ compared to the standard 1;he modification of [' '. ~~.~~ .._.___'~'_ __ ..

- ~~

{

,' design.

~ ~ ~ ~ . _ _

. 7 i

Since the changes to [ tinue to

, all the original structural criteria conhis modification besatisfiedwithth)emodifieddesign. The effects of which are v is primarily in the areas of [

discussed in detail below. . . .

III ', Fuel Assembly Performance _

3

.A. f

Thd conclusions. listed under Section IV. Reactor Operation .

portion of this reyort reraain bounding for the case where L

~'

These considerations include ef fects on scram time, CEA co

' ~fuel ~ ~} assembly uplif t, core physics, and ECCS performance.

~

j .

B. f ~

^ ' ' ~~

~

] will have the following effects ,

f

~

. bn reactor performance.

1. Scram Time _

{. - - _ . . . .

..and it is predicted based

. . e .

'upon in-housefully testing (that there will be an incre withdrawn to 907, inserted) over aHow v .

by about [ ] seconds t comparable unsleeved result. times will continue to fall belo

..F

,. g

.e, .. .

4

. - - . .. . . - . . . . ~ ,

,, 3 ., . . .

. I -

.,b design criterien

..E.'CCh*Cooln9, Even with conservative assumptions onMaine coreYankee conditions test for CCA cooling' is niet with substantial margin in the 4 -

- bundles. .

/

A cooling is that there shall be no bulkT f

,The criterion for adequate CE l operation. the guide tube at any

. . boi, ling in the guide tube during norma erature.

An analysis /

satisfied when the average coolant temperature Yankeein

- guide T. .

axial position does not flou exceeds exceed [di ]tionsIbmthe /hr.

anticipated The saturatio

, tubes at 1023 power if the cooling conditions used in the analysis envelope the d al are Thefull available Control rod positions from full insertion ilable. to with raw

.y

- quired by a signifi-considered in a calculation dle designs. For the bundles with of cooli

. for [ cant factor for botht bundle of designs. theis thattest bunar

~

,. the bundles with a[ [.'The conclusion J. the CEA's this factor is more than

. cooled satisfactorily with both of the tes l w Physics Design d ef fect 'on

', 3. .

l A review of neutronics considerations,dshutdown it is thus mar '

power distributien indicates no significant impact, anf

' concluded that there will be no appreciable e design. ,

1' ,

te and power

4. Effect on ECCS Performance ~

l

, . o Since there is only a negligible effect o

/

f mance.

. detrir,.cntal effcct ......

on ECCS per or

.., Safe ty_ Analysis

u. '5 . l d d that enl-

-o Howe'-

in considering the above mentioned effects, it wa i

- , . the increased scram time potent a ions of CEA the CEA insertion versus timet curve any reductbfor

' insertion (i.e., between 30 and 60% insertion).

demonstrates fuel assemblics capabil,ity.can be accu

. in operating flexibility of power .

h

.e ..6

,....ees, e .

. I g

'e sen . . . . . .- [

, ., - j c . , '

l

_ o . .

.Tc]tPro3ramt*.., *

<luacy of the( ber of tests have been run.

v *. ; . ,

In' order to'cyaluate the i ], a num i h a shortened fuel tests in .a single element

.I'-

These bundle, and include full size cold CEAflow in Tf-lS, visualization cold scopingtesting w t.d h , -

l

. flow visualization rig and cold an

.%, and CEA's in TF-2.

s ., .

A.

Single i ~Elercent Flow Visualization Tests

' This plexiglass single element fuel assembly guide test loop pe - . l flow induced vibration caused by the flow in the Testing in this loi.p has shown that[,

tube. ), through Similarly, the fuel testing asser..bly with thc[ guide tube es las -

' CEA vibratory motion.

]showed that the amplitude d responseof of theCEA vibration .

substantially reduced, compared to the observe .

' s- '

,{ '

j In' con'c[usion,theuseof] tould substantially reduce CEA vib ide tube. .

. motion res'ulting from flow in the gu B. TF-15' Tes ting .

f flow-induced vibrations

v. TF-15 test loop allows the visual investigation in various cctbinations. oide stru caused by flow throug'1 the fuel bundle,toupper b allow visual gu In addition,  ;

and scuppers , anu the fuel t of theassembly CEA.

erformance characteristic guidl observations of the flow paths and the h'have movemen indicatedpa standard instrumentation is utilizedto toconditions monitor associated

- Tests substantial havedecrease been conducted in CEA vibration in thisrelative test loo withtheuseof[

guide tube Testsflow rates associated with the[

also performed with[ ibration relative

].

]also showed a marked reduction in CEA fir ger v ,

l to results with standard design posts. .

In conclusion, the use of cither[should substantially reduce

.., j

, t wear of the guide tube ,

i l

the CEA vibratory motion and the result l

- in'ner surface.

• TF-2 Testing

- C. (TF-2) involves a 14x14 The full scale flow test in the CE test loop hich conser- ,

t d -

fuel assembly containing a S-rod CEA, a CE The bility of the[

components. l t

i vatively bound maximuu flow rates fo I ,.

sc. ram characterist'ics.

• . O~

j

. IT ,

..: . n tat \t%~1 .

• 'O ' *

~~~~

lic An11ES. 1

.- for CFA h,ati Thn -

7 ' ._r.u_al and 3l _drau c o r y Q 3 g &-2.gi tbi -

. v.

....K.

O_eggn,_ Con,dit_lgnL

' 1

. p g g ter_, . .

102% of 2630 Mat

. g ., .

- , 30% -

.-Co rc ' Povier - . .

1-

, _. , ,,. 1 Rod Insert. ion. 0100"., povier . .

. L '

Core Flovi Rate ,

552o F ,

Inlet Tc; perature 2200 psia '

l Core Pressure ,

Most adverse tolerance stack-up-cl Dimensions '

F L

} .

CEARodlleating(basedon2560 Mat) -

Radial Peaking Factor Belovl CEA Rod ,

Fac tor Above CEA Rod R

ial Pea;ing i

~'

Y Axial Shapc(all 14XI4) e *

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"* FIGURE 1 . .

florth

. ._ .3...

v______..._........:___..._.__......

~

o

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M difi' ti "

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O ruel'Bundic Assembly with i 9 Modification

~

O ruci Bundle Assembly with

• e 8

. . 4

. ., e

't * *

- t/,0DiflCAT10!! FOR 14X14 fuel. ASSE}1BLIES .

• O ,

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=* , . . . . .

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- FIGURE 3. .

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CEti-93(li)-NP ,

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Maine Yankee Cycle 3 .

. Guide Tube. Inspection and Analysis ., .

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Combustion Engineering, Inc. .

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- August 18, 1978 . .

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LEGAL 4'OTICE

'- - THIS REPORT WAS PhEPARED AS AN ACCOUNT OF WORK SPONSORE NEITHER COMBUSTION ENGINEERING BY COMBUSTION ENGINEERING, INC.

r.

NOR ANY PERSON ACTING ON ITS DEHALF: -

• l A. MAKES ANY WARRANTY OR REPRESENTATION. EXPRESS OR IMPLIED INCLUDING MEHCHANTABILITY, THF. WITH WARR RESPECT ANTIES TO THE OFACCURACY. FITfJESS FOR A PARTIC #

PURPO'SE OR

. ..COMPLETENESS, OR USEFULNESS OF THE INFORMATION CONT AINED IN THIS ,

REFORT, OR THAT THE USE OF ANY INFORT.1ATION, APPARATUS. METHOD, ~

• OR PROCESS DISCLOSED IN THIS REPORT MAY NOT INFRINGE PRIV .

'

• OWNED RIGHTS;OR .

f B. ASSUMES ANY LI ABILITIES WITH RESPECT TO T {E USE OF,OR FOR l DAMAGES TIEEULTING FROM THE USE OF. ANY INFORMATION, AFPARATUS, ,

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- - METHOD OR PROCESS DISCLOSED IN THIS REPORT.

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COMCUSTION ENGINEERING, INC.

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- MAltlE YAllKEE CYCLE 3

,i . , ' ' , ,'.. UO10E 1Ujp INSFECT10tl AND AtlALYSIS .

PURPOSE AND C0flCLUSI0t{ , . .

., J. .

The purpos'e of this document is to report information from the inspection of fuel assembly guide ' tubes perfor'med af ter the Cycle 3 shutdown at Maine Yankee. The information supplements that contained ,

in CEti-93(M)-flP " Maine Yankee Reactor Operation with Modificd CEA Guide Tubes", in that additional data on guide tube wecr have been obtained

, from fuel assemblies that have resided in the core for Cycles lA, 2, '

a'nd/or. 3.

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, c The new d'ata suppo,rt the assump' tion made in CEN-93(M)-NP that l

the Cycle'3 guide tube. wear conditions would not be significantly different from the observations and analyses used as bases for the conclusion that '

cortinued reactor operation is justified.

II. EDDY CURRENT TEST

SUMMARY

Guide tube eddy current inspections were performed on "

fu'el assemblies in the Cycle 3 core which had operated under control elements during Cycle 3 or dur.ing previous . cycles. Figure 1 sh'ows the Cycle 3 coil assembly locations in the core and the ayerage of the maximum rec.o rded for each of the five guide tubes. Also indicated are the 3 assemblies.

' [ ' cycles during which control elements were inserted into bundle type.

Table i summarizes the Cycle 3 eddy current inspection testing was ' performed using a mechanice hoist system that The inspections.

.,provided a constant withdrawal. ra,te for the prob. suring the

_.;~ e .

f average

., Review of th'se e data results' in an, updated tabulation o .

- of the maximum coil . - .

Average Maximum Fuel CEA Residence Operat'ing)_ All Guide Tubes Batch Time Time Olrs i

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.,' . ' . ' . ,- l ., - ~2- . GMECRING INC.

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These averages confirm the observation made in CEN-93(m)-NP that l

.the wear in subsequent cycles was less' than that measured for Cycle 1,. ,

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- - l in Assembly EF009A The maximum indicatien in any guide tube was ( _

which was located under a CEA during Cycle 2 only. The highest guide tube.. .- -

in meas.ured 'in an assembly containing CEAs durin.g . Cycle 3 only was ~~

r Assembly Glli. $ i 1

(

Eddy current inspections were performed on fuel assemblics from Cycles 2 and 3 which had resided in the. core locations where unsleeved test

- fuel asserhblies are to be placed during Cycle 4. The test assemblies are ,

coil recorded for the-described in CEN-93(M)-NP. The maximum , ,

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g'uide tubes in these locations are tabulated below.

~ .

xx Cycle ECT Volts **

Core Location _,_..__As'sembly. _ __ ,

c ._. + . .

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• Assembly EF003C was also in a CEA location during Cycle 1A.

+ Data could not be obtained due 'to presence of instrument thimble.

• • Li.sted in order of .NE,.SE, SW, NW,1C guide tubes.

~~

coi11 inspections were performed on a total oi _, guide tubes.

The resuliing data ' demonstrate that in all cases there is azimuthal alignment The between wear indications found at different elevations following Cycle 3.

different elevations reflect the fact that the control elements were inserted (The total additional [.. -) inches for 4560 hours0.0528 days <br />1.267 hours <br />0.00754 weeks <br />0.00174 months <br /> midway through Cycle 3. .

Cycle 3 operating time was 9710. hours).

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1 The lowest elevation 9f wear measured in the ECT exam in an assembly inches below the top of the fuel assembly ,

a to'be sleeved occurred at ,

l whichisconsistentwiththe[ ).dditionalCEAinsertionthatoccurred - -

coil at the i during Cycle 3. In the majority of cases, the _ _ _ _

'lowef wear elevation was the same or lovier in magnitude than those at the ' upper l l

clevation as might be expected based on CEA residence time. .

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III. 'REACTOROPERATIONANDFUELHANDLING_

Interpretat, ion ,and analysis based on the cddy. current data have led to tt'e follcwing results for the Cycle 3 fuel assemblies. __.

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(subsequently, (1) The assemblies with the highest

. analyzed with.the coil) had a degree of wear which

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1 cads 'to calculated stresses below the allowable values per the 1

- safetyanalysisinCEN-93(M)-NP. -

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• (2) All assemblies could be lifted without reinforcement.

during

- Th'e fpel assemblies whicti produced the' maximum coil i

.the Cycle 3 ECT exam were analyzed for guide tube stress levels in both the sleeved and unsleeved conditions. The stress values corresponding to the highest in Assembly EF009A) were the highest calculated. values coil ,

The stresses are substantially lower than the allowable and are listed in Table 2.

stresses listed in CEN-93(M)-NP. They are also lower than the stresses listed for the five worst Maine Yankee guide tubes, previously reported in that document, under

-lif ting, scram, and seismic conditions. ' Stresses during normal operation are ,

Although somewhat higher due to the increased holddown forces in the reload design.

not all of the worn fuel assemblies to be returned to the core for Cycle 4 coil in these

'have been'alalyzed for guide tube stress, the maximum _

, which is significantly lower than the fuel assemblies is For these twenty-four assemblies the average value indication discussed above. Figure 2 of the maxi. mum coil readings' for all 120 guide tubes is .

displays the cumulative frequency distribution of these data with respect to that Batch G bundles in this category have previously obtained at Maine Yankee. All ,

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been sleeved, and none is to ,be reloaded in a CEA loc'ation. ,

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INFORMATION COMBUSTION ENGINEERING, INC.

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The presence of multiple elevation wear indications on the guide tubes

- iocate'd under CEA's during Cycle 3 does not alter the stress analysis method.

This conclusion is based on the observed azimuthal alignment between the indications.  !

- The' calculated axial stress is not affected since it is a function of guide tube cross-section at one given elevation only, In the case of induced bending l stress, the two wear legions combine to increase the length of the more flexible segment of the guide tube. This improves the ability of the worn region to match the slope and deflection o'f the unworn length of the tube, 'an ef fect which actually lowers the bending stress.

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Because of the slightly lower Cycle 3 wear elevations in Maine Ya.nkee ._

than in St. Lucie 1 Cycle 1,11 sleeved fuel assemblies required the use of ,_

inch sleeves iristead of. the inch sleeves described in Cell-93(M)-NP. The longer.. .,

the same series of vents as ,-in the -- inch sleeve. The

. inch sleeve retained inch sleeve which placed

- slots were located inches from the bottom of the

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them at the same clcIation from the top of the fuel as'sembly as in the inch which extended from " to sleeve. There was also a - - _ . - -

inch sleeve above the bottom of the sleeve. All other features of the ~'

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were basically,the same as those of the inch sleeve. . . . .

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. '. inch sleeves was the same as that for The tooling to install the

,- 7 in

. inch sleeves with the exception of the expansion tools which were longer inch sleeves that order to be compatible wi.th the longer sleeves. For the ~~

inches of the sleeve was expanded were installed in worn guide tubes, the lower outward'so that the 0.D. of the sleeve and the 1.0. of the guide tube make contact at temperature. Additional'ly, a short region at the -lower end of the sleeve was expanded so that the guide tube and sleeve were permanently crimped.

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. TABLE'1 . .

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Malt!E YANKEE CYCLE 3 EDDY CURRENT' TESTING = -

=

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• No. of Guide *'

i Tubes Tested Type Test .

For  ;

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. Replacement Assemblies Containing -

i 1 CEAs During Cycle lA . ,

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CEAs During Cycles lA and 3 '. .

Batch E Assemblies Containing

CEAs.During Cycle 3 .

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Batch F Assemblies Containing - .

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CEAs During Cycle 2 .. .

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j Batch F Assemblics Containing '

- i CEAs During Cycles 2 and 3 .

. i Batch F Assemblies Containing. - -

8 CEAs During Cycle 3 r

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(.O Batch G Asnemblies Containing gZ CEAs During Cycle 3 2 q xD

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Table 1 - Continued

- No. cf Guide -

For . Tubes Tested ..

Type Test ,

1 I - "

Replacement Assemblies Containing i CEAs Dur'ing Cycle 1 A ,

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Batch F Assemblies-Containing -

CEAs During Cycle 2 ,

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' - Batch F Assemblies Containing .

CEAs Dur 's. ,ycles 2 and 3 o .

Batch G to ... sties Containing

. i CEAs During Cycle 3

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g GUIDE. TUBE OF BUNDLE _

COMPARIS0N OF SLEEVED AND UNSLEEVED STRESSES FOR THE .

s . .

SLEEVED STRESSES (KSI) ,

UNSLEEVED STRESSES (KSI) .

SLEEVE . GUIDE iUBE SLEEVE .-

LOADING CONDITION- GUIDE TUBE 10.4 9.7 17.3 N/A LIFTING - .

-5.6- -5.3 ,-

NORMAL * .

-9.4 N/A .

N/A -12.0 ,

'-11.2 SCRAM -20.0. ,

N/A 7/-12.1 7.4/-14.4 14.2/-26.7 .'4.

SEISMIC ..

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ide Tubes With . -

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Cumulative : Frequency Distribution. s of Guide Tube .

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