ML18219D912

07/01/1977 Response to Request for Additional Information XN-76-51, Supplement 1, Flow Blockage and Exposure Sensitivity Study for ENC D. C. Cook Unit 1 Reload Fuel Using ENC WREM-II Model.

ML18219D912
Person / Time
Site:	Cook
Issue date:	07/01/1977
From:	Jason White Exxon Nuclear Co
To:	Lear G Office of Nuclear Reactor Regulation
References
Download: ML18219D912 (12)

Text

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NRC DISTRIBUTION FoR PA Mr. George E. Lear GO FROM:

DOCKET MATERIAL EExxon Nuclear Co.

RichMnd,Washington Inc.

t U.S. NUCLEAR REGULATORY COMMISSION 99352 DOCICET NUMBER FILE NUMBER DATE OF DOCUMENT 07-01-77 S.

John A. White- DATE RECEIVED 07-05-77 gLE3'T E R 0 NOTOR IZE D PROP INPUT FORM NUMBER OF COPIES RECEIVED SIORIGINAL @UNCLASSIFIED Cl cop v S I C A)EjD DESCRIPTION ENCLOSU RE Furnishing esponse to NRC's questions of 06-08-77 concernin , Second-round Responses to XN-76-51, Supplement ., "Flow Blaokage and Exposu Sensitivity Study fog;ENC D. C. Cook Unit 1 Reloa Fuel Using ENC WREM N Model", dated 01-27-77...

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ECT MANAGER: PROJECT MANAGER!

ICENSING ASSISTANT: LICENSING ASSISTANT:

Bo HARLESS INTERNAL D ISTRI BUTION SYSTFMS SAFETY PLAiNT SYSTEMS SITE SAFETY &

HEINEMAN TEDESCO ENVIRON ANALYSIS ROEDER BENAROYA DENTON & MULLER ENGINEERING IPPOLITO ENVIRO TECH ERNST OPERATING REACTORS BALLARD YOUNiGBLOOD BAER VAK BUTLER GAMMILL 2 RO ZTOCZY GRIIP CHECK SI'ZH ANALYSiS VOLLMER AT&I BUNCH ALTZMAN J ~ COLLINS RUTBERG KREGER EXTERNAL OISTRIBUTION CONTROL NUiVIBER TIC NSIC EG IV J HANCHETT 771 P2P 1 7EI 16 CYS ACRS SENT CAT GO Y

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NUCLEAR COMPANY, Inc.

'QON 2101 Horn Rapids Road P. 8. Box 130, Richland, Washington 99352 Phone: (509j 943-8100 Telex: 32.8353 July 1, 1977 Mr. George E. Lear Division of Operating Reactors Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D.C. 20555

SUBJECT:

Second-round Responses to XN-76-51, Supplement 1, "Flow Blockage and Exposure Sensitivity Study for ENC D. C. Cook Unit~ Reload Fuel Using ENC WREM-II Model", dated January 27, 1977

Dear George:

Transmitted herewith is Exxon Nuclear Company's response to NRC questions received informally June 8, 1977 on the subject document.

The enclosed information was telecopied to Mr. P. E. Norian of the NRC on June 30, 1977.

h lit If you have any comments or questions regarding'he enclosed respons'es, please call.

Sincerely, ON NUCLEAR CO , INC.

John A. White Reload Licensing JAW:gf Enclosures As noted CC: Mr. Paul E. Norian (NRC)

Mr. James G. Feinstein (AEP) IQQ 5 IN1.

ggs /0 AN AFFILIATE OF EXXON CORPORATION

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ATTACHMENT A SECOND ROUND UESTIONS FOR XN-76-51, SUPPLEMENT 1 QUES'TION 2 Since'TOODEE2 twas designed to envelop bur'st str'ains, shy are "uniform" strains used as input?

RESPONSE

Uniform strains are not input to TOODEE2. Rupture strains are input.

The code then assumes that the. uniform striah is 0.2 times the rupture strain (c .). Thus, uniform strain is affected by the input rupture strain. Section 2.2 of XN-76-51, Supplement 1, indicates that a value of 0.263 x cR is a better estimate of the uniform strain. The use of 0.2 x cR is conservative since it results in higher pin pressures.

QUES'TION 2 Does Figure 4 contian meed strains (burst and "uniform" strains"? I' this figure used for. any purpose other'than as an illustration;

. RESPONSE Figure 4 represents 'measured flow area reduction for all cases except for ORNL single rod data. For the ORNL data, the single rod rupture strain was used in conjunction with a probability of coplanar blockage obtained from ORNL Multirod Hurst Tests. The purpose of Figure 4 is to indicate that the approved ENC model is very conservative when compared to blockage data steam environment from tests which are prototypic of the anticipated LOCA conditions.

Figure 4 is not used in the ENC model.

The rupture temper ture, as Listed in the ORNA repor ts, is the hottest

'I r'ecorded temperature, not necessarily the temperature obtained from the thermocouple located closest to the rupture. If the mpture temperatures

0 used in the data anaLysis vere aZZ the hottest recorded temper'atur'es, vouZd

, the resuZts be aZtered?

RESPONSE

If temperatures from the therriiocouples measuring the highest temperatures are used instead of the temperatures from the thermocouples nearest the failure location, then the correlating temperatures'or tests PS-17, PS-19, SR-l, SR-2, SR-5, and SR-8 would be altered. The location of data points on Figure 3, XN-76-51, Supplement 1, would be altered as shown in the attached'igure l.

All the measured uniform strains would be above the design correlation and no changes would be necessary for the application of the data. In some cases the highest temperatures were measured at locations over a foot from ,

the ruptured area and were n'ot thought to be as representative of the failure conditions ys the temperatures recorded nearer the failure location. Less than half of the data points were not at the maximum temperatures and only in the cases of PS-17 and SR-5, which were the lowest temperature failures,

.did the highest and failure zone temperatures differ by more than 100'F.

QUES'TION 4 a

In regard to question 4 of the fir'st r'ou>>d questions, Bar lou)'s,thi>>

u)aZZed equation is aZso.used in design for eZastic applications. Justify shy it is more appZicabZe than Iame's thick vaZZed equation.

RESPONSE

The'use of stresses calculated with Barlow's thin walled equation is more appropriate than the use of stresses calculated with Lame's thick walled equation in all applications where the inelastic components of de-formations are of -similar or greater. magnitude than the elastic components.

In many design applications concerned with primary stress limits, reference to yi.eld conditions has to do with the load carrying criteria associated with

,f the limit load. At the limit load, the full thickness of the section is

. 'at the yield stress. This type of criteria is used, for example, in the A.S.H.E. Boiler code. For the limit type evaluation, Barlow's equation is applicable.

For high cycle fatigue, for the determination of the onset of initial .

plastic yielding and for the deformation of brittle materials, the elastic solution o'f Lame is applicable. Such application's are most common in machine design, for rotating equipment and for vibrational and cyclic loadings.

Application of the appropriatedesign relationships have to be related to the situation being modeled and to the source of test data used to establish the design correlation. In the application for LOCA analyses, the cladding inelastic deformations .are orders of magnitude larger than the elastic -deformations, and therefore, the elastic solution does not properly describe the deformation process. The criteria. are associa-ted with the ultimate strength rather than with the fatigue strength. Thus, Barlow's equation is used and not Lame's.

b 0.5 CO I I Clt Clt 0.4 LSl 0 Rupture Strain t

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CL N + Uniform Strain I

LA CA I ~CL Clt t O t oCt I'7 I 0 O CC Clt 0

0.1 Design Non-Rupture Straan Lcm>t (c u = 0.2

• c R )

0

'400 '500 1600 1700 1800 1900 2000 . 2100 2200 Ropture Temperature ('F)

FIGURE 1 DESIGN STRAIN LIllITS DEPENDENCE ON TEMPERATURE AND ORNL ROD SIMULATOR TEST RESULTS IN STEA'1 STHOSPHERES

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