ML20197A439

Presents Results Indicating Impact Force on Fuel Assembly Spacer Grids Caused by Asymmetric Loads During Blowdown After LOCA May Be More Sensitive to Core Plate Motion than Originally Believed. (Encl to 7809180024)

ML20197A439
Person / Time
Site:	Harris
Issue date:	11/04/1977
From:	Stiger R IDAHO NATIONAL ENGINEERING & ENVIRONMENTAL LABORATORY
To:	Tiller R IDAHO NATIONAL ENGINEERING & ENVIRONMENTAL LABORATORY
Shared Package
ML20197A443	List: ML20197A439
References
NUDOCS 7809180026
Download: ML20197A439 (3)

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NOV - 4 1977 (p#

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E. Tiller, Directer j

Reactor Operations a progrens Division 7

Idaho Operations Office - COE 4

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Idaho Falls, Idaho 83401 Wi #

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I PWR FUEL ASSEMBLY MECWsHIC'L RESPONSE NIALYSIS - Stig-316-77 l

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.Ref: (a)

R. L. Grubb, P'.:R Fuel Assembly Mcchanical Respcnse Analysis, j

Idaho flational Encincering Lctoratory, RE-E-77-141, March 1977 j

(b)

R. L. Grubb, P.m Fuel Assemoly Mech:nical Response Analysis, j

Anendment lio.1, Idaho !!:tional Engineering Labarctory, j

RE-E-77-140, !!:rch,1977 (c)

R. L. Grabb and B. F. Saffell, Jr, Ilon-linear Lcteral Mechanical 1

j Response cf Pressurized 1!ater Reacter Fuci Assenalics, ASt:E 1

Paper 77-uA/0E-13, Occc cer 1977

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I (d)

H. !!uno, !!. Itizuts, and !!. Tsu :una, Development of Advanced l

Methed Fcr Fu:1 Seis tic Analysis, 4th International Ccnference f

en Structural l'echanics in ReactQr Technology, San Francisco, i

California, USA, August,1977 2

(c)

R. L. Grubb, Feasability Study for Bounding the Lateral PWR h,

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Fuel Assembly fleenanical Resconse Analysis, Idaho National l

EngineeringLaboratory,RE-E-77-160,Rev.1,yuly,1977

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Dear !!r. Tiller:

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i A parametric study to assess the effect of variations in care plate motions 1

on fuei asscnoly sracer grid crusning leads is currently in progress.

A i

sum.ary descriptien of this study inciuding prelimincry results ha: bcen 1

prepared at the rc:uest of the tu: Tear Requia: cry Ccn-ission's Civisten of Systen Safety, Cere perfer an:c Eranen. Results of this study incicate l

that a small variati:n in c:re plate frecuency rr.y have a significant effect on spacer grid crushing loads. As the study is not complete, thcsc l1 results should be considered preliminary.

A mechanisin t.:s pcstulated in Reference (c) which indicated that the in-i put core plate retien could significantly affect spacer crid crushinn 4

' loads. The prir. cry objective of the present study was to deternine if

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this rechanisin c:uld b: shnun to exist. A secondary ob.fcetive is to compare linear end nonlinear analysis tecnniques.

In surrary then the l

purpose of this study is twofold:

(1) Statistically determine the effect of c:ra plate frecuency

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j and magnitude en the fuel assc oly raxinum spacer grid i

S crushing leads, and i

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l (E) Statistically c: pare iincar :nd nenlinecr analysis rctheds for lateral fuel asser31y -c: Manic:1 raspenso in an attcmpt "g

to simplify the n:nlinear analysis.

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R. E. T:ller Nov. -4 1977 S ti g-316-77 Page 2 1

'The structural model utilized to analyze the fuel assembly mechanical response is basically described in References (c) through (c). Two i

exceptions included in the present study are the use of fuel assembly experimental frequencies and mode shapes and utilization of the nicthod 8

presented in Reference (d) for calculation of scaccr grid crushing loadt. The nominal forcing function, core plate acceleraticns, are presented in Reference (b). hile eight variations on the frequency

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and ar.iplitude of core plate motions are to to considcred, only the four cxtretc cases arc addressed in this discussic.n. The (nur cases are

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& 10" variation en frequency and + 10'. variation of the anplitudc.

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Is noted thct all the frecu'encies~;:ntained in the core plate cotinns are varied the sa.-e amount. Menlinean dynanic analysis as descri:ed in References (a) througn (d) is in progress and preliminary results are provided in TaDie 1.

A linear analysis is also being pursued using

.the methods outlined in Referen:e (e).

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TABLE l' RATIO OF PEAK SPACER GP.1D CRUSHING LOAD TO TtlE 1

I N0ftINAL CUR 5HING LOAD

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Maximum Crushing Load / Nominal Crushing Load'

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"C.~~~~~. Spacer Grid Elevation

-IC5 Frecuency +10C Frecuenj:y, -100 Amalitude '105 Amolitude

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Center 1.76 0.60 0.979 1.04 i.d5 0.Saa 0.Sa2 1.23

,,, Center-up Center-da.n 2.11 0.830 0.035

- 1.25 Top 1.34 0.545 0.771 1.24

. Bottom 1,56 0.E05 0.363 1.26 Nominal crushing 1 cad is the peak spacer grid crushing lead obtained 1

from the base case core plate -oticns.

l Based on the results in Tatie 1, it oces anecar that a variation in frequency of ten percent effects a significant change in the s acer grio crushing icac:.

This indicates that s eariatien in this para-c:ar may be in or:er 'nr this t, e

of nonlinear crc', sis.

t should te ;ointtd out that the mccel s:vcier, rc -

s resents a generai ter'i uraticn. The rurpose ci this study was not a circ::

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d analysis of a s:ecific plent ut to cetermine if th.e mechanisin pcstu:ated e

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R E. Tiller tidV - 4 1sil Stig-310-77 Page 3

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4 Reference (e) could actually be clicited in the nonlinear analysis. The mech-anisin appears to cr.ist; thereby causing concern that per anent dcfomation of spaccr grids ray cccur.

Upon cocpletion of this study the conclusions presented in Cr.ference (b)

Vill be reassessed, i

Very truly y'ours, CUc!Nft' SIC:C0 3Y R. R. Stiger, l'anager Reactor Gehavior Division SFS:cij V. Stcllo, tiRC-00R P. S. Check, fiRC-OSS

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S. B. Kim, liRC-DSS 2

R. J. liattscn, t;RC-CSS R. O. licycr, flRC-OSS 1

D. F. Ross, tlRC-CS5 R. it. Michn, EGIG Idaho bcc:

R. L. Grubb R.11. liacek l

C. A. Pcore C.F.Obenchain60<;.L' B. F. Saffcil

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G. L. Thinnes T. R. Thompscn l

P. H. Vander Hyde L. J. Ybarrondo Central File File m

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