ML19211A826

Forwards Proprietary & Nonproprietary Response to NRC Re Fuel Assembly Guide Thimble Tube Wear.Application & Affidavit for Withholding Proprietary Info Encl.Document Withheld (Ref 10CFR2.790)

ML19211A826
Person / Time
Site:	McGuire, Mcguire
Issue date:	12/14/1979
From:	Parker W DUKE POWER CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
NUDOCS 7912210151
Download: ML19211A826 (34)

Text

{{#Wiki_filter:. DUKE POWER COMPANY Powra Bun.omo 4c2 SouTa Cacucu STnzzT. CRARLoTTE N. C. 282M w t LLI A h4 C. PA R K E R. J R. v.c c P.c.cc., December 14, 1979 retc. o.c: 4.c.,e. Steame PacDUCTION 3 73-4C 83 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 Attention: Mr. R. L. Baer, Chief Light Water Reactor Project Management Branch No. 2 Subj ect: McGuire Nuclear Station Docket Nos. 50-369 and 50-370 Fuel Assembly Guide Thimble Tube Wear

Dear Mr. Denton:

Attached is Duke Power Company's response to Mr. R. L. Baer's letter of September 11, 1979, concerning fuel assembly g ide thimble tube wear. Westinghouse Electric Corporation has also rest ided to this concern in' letters from Mr. T. M. Anderson, Westinghouse, dated June 27, 1979, November 10, 1978, and September 12, 1978, (References 1, 2, and 3 of Mr. Baer's September 11, 1979 letter). In addition, this concern was discussed in a meeting between Westinghouse and the NRC on October 12, 1979. is the proprietary version of our response, and Attachment 2 is the non-proprietary response. Attachment 3 is a copy of the Westing-house Application for Withholding Proprietary Information from Public Disclosure. As this submittal contains information proprietary to Westinghouse Electric Corporation, it is supported by an affidavit signed by Westinghouse, the owner of the information. The affidavit sets forth the basis on which the information may be withheld from public disclosure by the Commission and addresses with specificity the consideraticns listed in paragraph (b)(4) of Section 2.790 of the Commission's regulations. Accordingly, it is respectfully requested that the information which is proprietary to Westinghouse be withheld from public disclosure in accor-dance with respect to the proprietary aspects of this application for with-holding or the supporting Westinghouse affidavit should reference CAW-79-40, and should be addressed to R. A. Wiesemann, Manager, Regulatory and Legislative Affairs, Westinghouse Electric Corocration, P.O. Box 355, Pittsburgh, PA 15230.\\ p enocoq Veq t ly vours, p \\ h \\ ,636 013 %/ William O. Parker, Jr. % I 5 THH/sch Anniversary Attachment o

1. j oWER 7 912210 [

h

g Westinghouse Water Reactor usar unen osision Electric Corporation Divisions s a 353 PittsturgfiPennsylvanta 15230 November 7, 1979 CAW-79-40 M'r. H. R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 APPLICATION FOR WITHH0LDING PROPRIETARY INFORMATION FROM PUBLIC DISCLOSURE

SUBJECT:

Diablo Canyon, Units 1 and 2 (Docket Numbers 50-275 and 50-323) McGuire, Units 1 and 2 (Docket Numbers 50-369 and 50-370) North Anna, Unit 2 (Docket Number 50-339) Salem, Unit 2 (Docket Number 50-311 Sequoyah, Units 1 and 2 (Docket Numbers 50-327 and 50-328) Responses to NRC Questions on Guide Tube Thimble We&r REF: Mr. W. O. Parker, Jr. 's letter to Mr. H. k. Denton. dated December 14, 1979 Gentlemen: This application for withholding is submitted by Westinghouse Electric Corporation pursuant to the provisions of paragraph (b)(1) of ICCFR Section 2.790 of the Commission's Regulations. The accompanying affidavit identifies the information sought to be withheld from public disclosure, sets forth the basis on which the information may be withheld from public disclosure by the Commission, and addresses with specificity the considerations listed in paragraph (b)(4) of Section 2.790 of the Commission's regulations. The undersigned has reviewed the information sought to be withheld and is authorized to apply for its withholding on behalf of Wertinghouse, WRD, notificaticn of which was sent to the Secretary of the Commission on April 19, 1976. It is requested, therefore, that the Westirighouse proprietary information being transmitted by the involved utility letter referenced above be with-held from public disclosure in accordance with the provisions of 10CFR Section 2.790 of the Commission's regulations. 1 1636 014

Mr. H. R. Denton November 7,1979 CAW-79-40 Correspondence with respect to the proprietary aspects of this appli-cation for withholding or the accompanying affidavit should reference CAW-79-40 and should be addressed to the undersigned. Very truly yours, Robert A. Wiesemann, Manager Regulatory & Legislative Affairs /bek Attachment cc: J. A. Cooke, Esq. Office of the Executive Legal Director O D O e

= e CAW-79-40 ..-FIDAVIT COMMONWEALTH OF PENNSYLVANIA: ss COUNTY OF ALLEGHENY: Before me, the undersigned authority, personally appeared Robert A. Wiesemann, who, being by me duly sworn according to law, deposes and says that.he i's authorized to execute this Affidavit on behalf of Westinghouse Electric Corporation (" Westinghouse") and that the averments of fact set forth in this Affidavit are true and correct to the best of his knowledge, infomation, and belief: U $A.lllZW Robcrt A. Wiesemann, Manager Regulatory & Legislative Affairs Sworn to and subscribed befremethis7 day of 979. A lWef u Notary Public[ l./' g b, c..r >,,) c... I ...u-i. e ,:, n...w, .s-1636 016

CAW-79-40 _2 (1) I am Manager, Regulatory and Legislative Affairs, in the Nuclear Technology Division, of Westinghouse Electric Corporation and as such, I have been specifically delegated the function of reviewing the proprietary information sought to be withheld from public dis-closure in connection with nuclear power plant licensing or rule-making proceedings, and am authorized to apply for its withholding on behalf of the Westinghouse Water Reactor Divisions. (2) I am making this Affidavit in conformance with the provisions of 10CFR Section 2.790 cf the Commission's regulations and in con-junction with the Westinghouse application for withnolding accompanying this Affidavit. (3) I have personal knowledge of the criteria and procedures utilized by Westinghouse Nuclear Energy Systems in designating information as a trade secret, privileged or as confidential commercial or financial information. (4.) Pursuant to the provisions of paragraph (b)(4) of Section 2.750 of the Commission's regulations, the following is furnished for consideration by the Commission in determining whether the infor-mation sought to be withheld from public disclosure should be withheld. (i) The information sought to be withheld from public disclosure is owned and has been held in confidence by Westinghouse. e e 1636 017

CAW-19-40 s ' (ii) The information is of a type customarily held in confidence by Westinghouse and not customarily disclosed to the public. Westinghouse has a rational basis for determining the types of information customarily held in confidence by it and, in that connection, utilizes a system to determine when and whether to hold certain types of information in confidence. The application of that system and the substance of that system constitutes Westinghouse policy and provides the rational basis required. In determining whether information in a document or report is proprietary, the following criteria and standards are utilized in Westingho.use. Information is proprietary if any one of the following are met: (a) The information reveals the distinguishing aspects of a process (or component, structure, tool, method, etc.) where prevention of its use by any of Westinghouse's competitors without license from Westinghouse constitutes a competitive economic advantage over other companies. (b) It consists of supporting data, including test data, relative to a process (or component, structure, tool, method, etc.), the application of which data secures a competitive economic advantage, e.g., by optimization or improved marketability. e 1636 018

CAW-79-40 (c) Its use by a competitor would reduce his expenditure of resources or improve his competitive position in the design, manufacture, shipment, installation, assurance of quality, or licensing of a similar product. (d) It reveals cost or price information, production capaci-ties, budget levels, or commercial strategies of Westing-house, its customers or suppliers. (e) It reveals aspects of past, present, or future Westing-house or customer funded development plans and programs of potential commercial value to Westinghouse. (f) It contains patentable ideas, for which patent protection may be desirable. (g) It is not the property of Westinghouse, but must be treated as proprietary by Westinghouse according to agreements with the owner. (iii) The information is being transmitted to the Commission in con-fidence and, under the provisions of 10CFR Section 2.790, it is to be received in confidence by the Commission. (iv) The information is not available in public sources to the best of our knowledge and belief. O O t 1636 019

CAW-79-40 _, (v) The proprietary 1-formation sought to be withheld in this sub-mittal are the responses to NRC questions related to guide tube thimble wear directed to applicants for operating licenses for Diablo Canyon Units 1 and 2, McGuire Units 1 and 2, North Anna Unit 2, Salem Unit 2, and Sequoyah Units 1 and 2. Public disclosure of this information is likely to cause sub-stantial harm td.the competitive position of Westinght use as it would reveal the basis of the Westinghouse fuel assembly design for the designated plants and similar plants, which is recognized by the Staff to be of competitive value and because of the large amount of effort and money expended by Westing-house in development.of this design. This information.is valuable to Westinghouse because: (a) Information resulting from this design gives Westinghouse a competitive advantage over its competitors. It is, therefore, withheld from disclosure to protect the Westing-house competitive position. ~ (b) It is information which is marketable in many ways. The extent to which such information is available to competi-tors diminishes the Westinghouse ability to sell products and services involving the use of the information. O 1636 020 e e6

CAW-79-40 _ (c) Use by our competitor would put Westinghouse at a com-petitive disadvantage by reducing his expenditure of resources at our expense. (d) Each component of proprietary information pertinent to a particular competitive advantage is potentially as valuable as the total competitive advantage. If com-petitors acquire components of proprietary information, any one component may be the key to the entire puzzle, thereby depriving Westinghouse of a competitive advantage. This information enables Westinghouse to: (a) Justify the design basis for the fuel (b) Assist its customers to obtain licenses (c) Meet warranties Further, this information has substantial commercial value as follows: (a) Westinghouse sells the use of the information to its customers for purposes of meeting NRC requirements for licensing documentation. (b) Westinghouse uses the information to perform and justify analyses which are sold to customers. ~ 1636 0'21

a. r CAW-79-40 . (c) Westinghouse uses the information to sell nuclear fuel and related services to its customers. Public disc'osure of this information is likely to cause substan-tial harm to the competitive position of Westinghouse in selling nuclear fuel and related services. Competitors could obtain the equivalent information, with difficulty, by investing similar. sums of money and provided they had the appropriate resources available and the requisite experience. Further the deponent sayeth not. e 9 1636 022 9

F ATTACHMENT 2 NON-PROPRIETARY VERSION ..g s. .) .t.r g t. g ^'. j . = ~ _ c .~. a ...9

+..

i ,.t * .n

s

.u -r-t. ../ gi ..t.- o .c.. - y,, = *

• s..

~

• 4
• s

..3, p-, f .r.,. p r a '_. .e f i, 4.-. r u-s ts:.y t ..a:,

.g

.m.;< r ~ s) ,s.,'- '~ ~. a. t. .._e- .a. j; .s- . - -.+ w. ga .,.g, m. L

.g,...

} 21 j. p ...s p 'z . 1636 0 :a e .r. a e e 6. i - .B l ) ef. s s. e 5 s S 'g a

.s . QllESTI0tt 1 Please provide the basis and derivction of the guide thimble wear mode In particular, explain assumption 4 and the equations provided Does the model predict maximum local ucar or average circum-in Reference 1. under assumption 7. ferential wear? RESP 0l!SE 1 l d the . Consider the interface between the guide tube, the control rod asscTb fuel assembly, shown in Figure 1. internals by the guide tube, and ia th tube. The rodlet is clampad against the guide tube by the coolant pressure,. as The length of the clamped portion depends on the conlant pressureThe rodle in Figure 2. and the alignment of the guide tube with the fuel assembly. is pinned in the fuel assembly guide thimble tube. As illustrated in Figure 2, a certain portion of the absorb:r rodlet, with a [.[i "L", is unsupported. As shown in Figure 3,[- .] The correspondin. vibration of the c'ylindrical redlet results in the oscillatica of t!.3 pinr.cd rcci n ' The ampiitude c,;esr natice i; a h 'c. tip, with a maximum angle of rct: tion 3. of this angle, as shown in Figure 4. U.e maximum angle of rotation e is [1, 2] V2 e= 5.72 Q 4(x ) f g p where: Q is the magnification factor is the fundamental clampad-pinned mode shape 4 is the abscissa of the dynamic lift force ,xpf is the fraction of F at red frequency g F, is the dynamic lift force L is the unsupported length ~ K is the rodlet dynamic stiffness ~ The total travel of the rodlet tip, in contact with the guide thimble tube inner surface, is: 2 0 0, f t ~ T = n where: D,is the rodlet diameter is the rodlet natural frequency f is the total vibration time; this is the total time during whiclr n t the rodlet is parked in a given axial position. 4 O ~ P00R OR8 R

"2-Finally, the wear volume associated with this travel is F.T.W. V = is the lateral contact force between the rodlet tip and the thiable Where: F tube W is the wear coefficient ~ In order to convert the wear volume into a wear depth, censider a typical wear scar in Figure 5; frca the observations of wear scar geometries, the wear depth U can D be deterr.iined from LN f W.dL [a,c] ^ [ ] and V = A 0 where: U is the wear area A L is the axial length of the waar scar g Figurc 6 repres:nts a wear'scer as mctsured in a thir.,bic tube and confirn-ti.2 illustration of F; cure 5. to the carameters ffe: - The above equations relate the maximum local wear depth '..'D ing the redlet vibration: geometries, flow, stiffness and the wear phenomenen: contact force, time, wear coefficient. References _: Y. C. Fung " Fluctuating lift and drag acting on a cylinder in a flow at [1] supercritical Reynolds numters", Jal aerospace science, vol. 27, No.11, November, 1960. W. T. Thomson, " Vibration theory and applications",1965 Prentice-hall, [2] eg. 10.7-14 Appendix C. E000 00$$\\lk ~ l636 025

~ ~ - ~. - -... ~. _ Question 2 Using the guide thimble wear mcdel, Ucstinghouse has ' predicted max and stress intensity limits for vorn guide thimble walls in tuo fuel asse handling load. These calculated values designs, which were subjected to a 69 We note that the stress intensity limits are listed in Tabic 4.1 of Reference l. increase as a function of time for both fuel assembly designs and l is always remain greater than the maximum stresses,'..hich increase From the supporting discussion prcceeding Table 4.1, it is no if the stress intensity limits are time dependent. worn away. t ial the noted increase in stress limits, but does not address the decreas toughness, associated with irradiation hardening. 4.0.5 it is contrary to tne previous Westinghouse position in of Reference 1. Show that the criteria adopted represents the more irradiation strengthening. conservative approach. RESPONSE 2 l The accelerations and resulting loads applied to a fuel asserhiy 1, 2, 3 and 4 operations are non-cperational leads, as opposed to ccnditions induced loads. ir.cccase of the In analyzing the non-operational loads, credit is taken for th: yield and ultimate streng-h with irradiation. On the other hand, the fracture analysis is performed to address As you mention, the matec hl toughness, characterizcd tyfu the critical stress intensity factor, should be a decreasinThe critica material toughness. d enocal d the maximum experimental value from tests on 40'e ppm hydrogen charg and therefore of tima. zirgaloy 2 after irradiation to 2.5 x 10'0 n/cm, E > IMW. (i] 2 lie: This minimum value, appliccble to 250 week results, has conserv to 25 week results in Table 4.1 cf our report US-TMA-2102. ^ ~), will be in a In additicn, the postulated crack in a thimble tube, [ 1he 25,000 state of plane.. stress and thereby will develop t i test resuit: represents a lower bound toughness. idern In summary, credit is taken for irradiation hardening when Sy derived from for non-operational loading conditions. vatively used, regardless of irradiation; this e ~ ii This load is significantly handling load has been assumed. nior higher than the actual load actually imposed on the fuel d In addition, a 69 i h resu.ts No credit is taken for the unev" load distribution in the thimbles ., reached. 8. in load transfer when yiciding represents a lower bound as indicated in Response to Question l Reference _ R. G. Hoagland and R. G. Rowe, " Fracture of irradiated Z of Nuclocr Materials 20 (1969), p. 179 - 195. 1. )

OUEST10:1 3 Guide thimble wear data, which were taken from Point Beach Units 1 and 2 spent fuel, are discussed, listed, and plotted in Section 2.3, Table 2.1, and Figure 5, Please confirm that the time units in Section 2 3 respectively, of Reference 1. Should not the enits and Table 2.1 are in error and make corrections as needed. be days instead of hours? RESP 0?!SE 3 The units should be .The time units in Section 2.3 and Table 2.1 are in error. days instead of hours. ~ 300ROR8Na G 9 e 0 e e 9 e e o e h e W O 9 e 9 1636 027 9

QUESTION A Submitted Westinghouse information does not explain why the guide thimble wear model, which was developed from measurements taken on two 2-loop plants with 14 x 14 fuel assemblies, is applicable to wear predictions on plants of other designs. Other NSS-vendor-designed plants have experienced a " plant specific" and " core-position" dependence in the observed wear. Therefore, please explain how the model accounts for wear differences and provide supporting data for all Westinghouse design variations. If the analytical treatment of design variations are justified, the supporting data can be provided in a confirmatory manner after NRC approval of the model. Please provide details of your data-gathering proposal, a schedule for its implementation, and state your commitment to carry out this confirmatory program. This data-gathering program should be completed expeditiously considering the availability of irradiated assemblies in all Westinghouse plants. RESPONSE 4 A confirmatory program to assure the validity of the Westinghouse guide thimble tube wear analysis is currently being evaluated by Duke, Westinghouse, and the four other affected utilities. This evaluation will be completed and the results transmitted to the NRC by February 15'. 1980. 1636 028

u. QUESTION 5 In Reference 3, n2stinghouse stated that the offect of hydrogen content on the mechanical properties of Zircaloy is discussed in WLAP-9179 (Reference 4). Uc have retiewed that topical report and found no information on this issue. Please provide your evaluation of how this consideration affects the safety Include in this evaluation a description of the propensity for hydrogen analysis. uptake of th. Zircaloy as a function of the accumulative wear. RESPONSE 5 Hydrogen measurements on a thimble tub exposed in UEP Point Beach Unit 1 fo ] [ ). At one location in a bulce { one cycle were [ Haximum pre-irradiation hydrogen content was [ [ joint the hydrogen concentration, cbserved catallographically, [The hyd ]

).

3 [. I compared to the maximum measured value of [ 3 { Af, the Westinghouse Research Laboratorics in Pittsburg ,] and sr.li ble:s: Zircaloy-4 tubir.g, [ These tests were cenducted for fcur days in 6CO'F ::cter of 304 stainless steel.containing 1500 ppm beren and aaintained at a PH of s 6 0 The

M ' s The measured hydrcgen content in ths water was 42.33 cc per Kg i:3 of this test snc.ved that [

J. Earlier investigations into the effects of hydride platelets on the fractureRailed toughness of Zircalcy-2 were conducted at E2ttelle " orth. est Laboratories. Co, Cl C5 plate matcri:1, of reactcr grade Zircaloy-2 (i.44:, Sn, 0.lisi. Fe,.092: Nu) were additionally cold.sorked by roiling to levels of 0, 20 and 40:. A number of annacled spe:i. :ns r in thickness and anntaled at 750 C for one hour. (grain s'ize of.035 to 0.40 mm) were charged with hydrogen to levtis of 1 Metallographic examination revealed the for73 ti d 400 ppm at 460 C. hydride distribution. level, a minimum ioughness of K c = 25KS1 /in. was l In addition, at higher test te:nperatures, the toudhness and.400 ppa concentratirq obtained between 0 - 20 C. increased, and no sub-critical cracking was observed above 120*F. ] in the Therefore,[ The critical stress intensity factor, 25 Ksi /I_n. used'in Table 4.1 of the analysis was appropriate for safety analysis of t Uestinghouse to NRC response. wear. e O 1 4 7,t, n' 7 1 u,, e

QUESTI0ft 6 When Eddy current testing was conducted on worn guide thimble tubes from the Point Beach Units, did the presence of zirconium hydridas affect the results? How sensitive is the interpretation of oddy current signals to hydride presen Ilow is this effect taken into account? RESPO!!SE 6_ Eddy current measurements that were taken at the Point Coach spent fue J. [e The effect of these components is to increase the resistivity of the Zircon [- [ [ E ] The wear depth was obtained as the difference between the signal in the unwor [ [~ [ zone minus the signal in the worn zone. [

3. The worn zene being [This results in an apparent thinble tube thincir.g in i].

the worn section. fio attempt has been rade to include this effect in the data evaluation ct.2 to its conservative nature. ?00R DML O 9 9 em e G G e e o O e 1636 030 e

~ ~ QUEST!0::7 ceasequences of hole formation in worn References 1, 3, and 5 do not address thaMoreover, it is not clear from the submitte if Westinghouse (1) has observed holes during in pection of the 49 guide thimble guide thimble tubes. tubes that were examined in the Point Coach spent fuel, or (2) has predicted (w the guide thimble wear model) hole fonnation to occur during projected fue Also, if holes have been observed or are anticipated, provide a discussion on the impact of such holes on guide thimbic tube i time. Please clarify. This discussion should control rod motion, and thermal-hydraulic performance. also account for ficw-induced vibration resulting in crack prorgation and This possibly fatigue fracture in locally thinned areas of the thimble wall. discussion should address the integrity of the thimbie assemblies are not under RCCAs. RESP 0:!S' 7, Westinghouse has not observed holes during inspection of the 49 guide that s;cre excuincd in the Point Esach s; ent fuel. The prdictions of the guide thir.bic wear m: del are presented in Figure report liS-T"J-2102. They rc?rcsent a [ 3. At [ l ]. All the curves are [ ]. [ { 3-in The ficw induced vibration of the fuel cssembly will result in cyc ],theimplitW2 the guide thir.ble tubes. the maxi.ua stresses are originated frem the [ of vibration [1The analysis of the vibration of a worn-through thimble tu ']. the peak to peak stress, at the wear scar, is [] vibration amplitude was con curve sho,n in Figure 7. A[ The thermal hydraulic imcact of a worn-through th The calculated to be [ ] would have to be worn thrcugh in ]. At least [ order to increase the core bypass flow by [] this effect in insignificant. The worn cross section is located above the absorber rodlet bottem en h which guides the rodlet and, therefore, does not jeopardize the mov control rod assembly. The impact of such a hole on guide tube integrity is provided in our re NS-TMA-2102. e a 9 0 e

QUESTI0il 8 During the review of UCAP-9179 (Reference 6), the staff questioned the Ucstinghouse value for the ultimate tensile strength of Zircalcy comnonents. The subsequent Westinghouse response (Reference 2) stated that the ultimate tensile strength of Zirecloy was not_ used in the design analyses of present However, the analysis contained in Reference 1 uses fuel asse::bly designs. Therefore, please sub: lit for the ultimate strength as a limiting variable. review the Ucstinghouse correlation for the ultimate tensile strengtn of Zircaloy. RESP 0"SE 8 Unirradiated values for.2% yield strength and ultimate strength used were lower bound values as indicated below: ] [6 Yield Strength [ 0 5 TF 1 600'F Ultimate Strength [ ] [2 0 < TF < 600*F 1rradiated values of.2!; yield strength used were lower bound values indicatcd below: iteldStrength [ ] [c 0 < T*F < 600 F nyt > 6x1020 (;, ); Because of the limited unifonn elongation present in irradiated annealed Zircaloy-4.I the [, ( The values for ultimate strength of Zircalcy-4 are used for failure analysis toOrigin: determine both failure mode and margin available for particular ccc.penents. design and analysis is based on the yield strength for Zircaloy-4. 1636 032 ?00RBRMll O e e m ee y

QUESTI0i 9 Section 4.1 of Reference 1 states'that the stress intensity factors are plotted This is as a function of time for 14x14 and 17x17 fuel assaablics in Figure 5. Please provide such a figure or amend Figure 5 as necessary. not true. RESPO!!SE 9 The stress intensity factors are plotted as a function of time for 14x14 and 17x17 fuel assemblics in Figure 6 of our report !!S-T;'A-2102. P00R BRGNM 1636 033

?- n 00!*sT10rl 10_ Per item 4, Section 4.0 of Reference 1, your analyses are based on unifo ~ Address the margin of conservatism for this assun.ption. Compare your results with annlysis that considers non-unifonn wear in all thimble tubes. direct !!ote that such shif ts will result in bo in a shif t of the neutral axis. stress and bending stresses. RESP 07:SE 10_ Assumption 4 of Section 4.0 states that wear is assu for occur in a thimble tube under a split tube, or sheath, location is the same thimble tubes. all thimble tubes under a split tube, or sheath, in this fuel assembly. Point Ecach measure =2nts show wear results that vary, within assembly, from thichle to thimble. the maxi;.:um predicted local wear is i fuel does not take credit for this observation: applied to all thimble tubes under a split tube, or sheath, in a g ven assembly. l As discussed in the response to Question 1, the model dces pr f the r.eutral wear, and Our analyses do take into consid: ration the snif t o axis and the resultir.g cirect and bending stresses. DDR OR M 1636 034 9

• e e

~. ~ -~ QUESTION 11_ For Condition 1 and 2 load analyses of Rcrorence 1, a sken factor is Clarify hcw the ske.i that accounts for the uneven axial load distribution. factor is related to both gecretric changes (rcsulting from unevcn wee How does the skew factor impact the load analy:es? assently misalignment. RESP 0MSC 11 During fuel assembTy mechanical testing, strain ga [, The measurements showed that,1 in the fuel assembly. ~ ~ 1[ ].L .] It was conservatively assumed that all this51e tubes under a split tu;e location l' ave the sre load as the tute Similarly, all chic le with the maximum load, in a split tube location. tubes under a sheath locaticn have the scac lead a, the tub. i-h the [ maximt:1 loac en a sheath locaticr.. Inadaition,! {~ ] This is due to the fact that the grn; di:tri:en The ske.t factors usec cor-e:pc' tc the loads over thimbles and fuel rods. thu top span although the stress analysis is done one spin tchw, were tt-This tends to overestimate the skca facters and, weaf scar is located. therefore, the load en the thimbles. P00RBRBlWL 1636 035

QUESTI0il12 2.

Ilowever, 2 in Reference 1 appears linear with tic:

The equation for the wear volu:.: in Figures 5 and 6, wear depth is plotted versus tiina, and the resulting correlation Picase provide information on how these parcn:cters are appears to be non-linear. related. RESP 0t:SE 12 The nca-liner.rity of the wcar 4pth versus tiac relationship is discussed in the [c Response to Question 1. It results frem [ [t ] 300R ORGINAL P 1 1636 036

QUCSTI0il 13_ For Condition 3 and 4 load analyses, described in Reference 1, it is s that the stresses in a worn guide thimble tube are based It is also stated that the stresses in the unworn guide thimble tubes calculations. for the reduction of the tube cross-section due to tne found. are increased to accountThi would indicate credit for a load redistributi J iccd Is a skcu factor er.: ployed in the Condition 3 er.:: wear scar. guide thimble tubes. Describe the state of stress in the worn guide tubes and he.e tne ~ analyses? uneven wear affects the load-bearing characteristics of the worn tub RESP 0ftSE 13 The Condition 3 and 4 load analysis fcr the worn thimble tubes was base [r generic seismic plus LCCA eve.nc thidle stress values, [These str~sE " D ], fro:a 1.'.;P 8235, Addendun 1. are calculated using finite elements core cce2is as described in 'Z'> SE. The stresses calculated in h' CAP 8235 Adder.duc 1 are strcsses unworn guide thimble tube. tube cross-section reddction and neutral axis sh For a given thimble tube, the wear re:uits in in the wear analysis. increased stresses and no credit is taken fur le5d redistributien. RODR OWL 9 e m t ' ' ' /. nI7 .lOJu ust

.. t QUESTIO!1 14 Discuss the '+cntial for guide thimble wear in fuel assemblics with hcr than control rod assemblies. core com.ps .3 REF .i 14 thimble plugs, Core components other than the control rod assemblies are:Both the bur burnable poisons, and sources. are "long" rodlets that arc inserted de.!n to the dashpot, while the thimble plug is a short rodlet. fuel assembly. rest on the top nozzle [a to [- J This has been confirmed by the cbservatiers r, performed en Point Beach Unit 2 fuel assembly q57, which had a b [a poison assembly durir.g one cycle of operat. ion,L [c 3 ?00R(112R e o G G 4 e 1636 038 O 4

• e e

e e e

N* L k_1 H W s,' .. C R,.,..d m i r-- i ...;..u.....;. x .= ~ RCC Assemb 7' G-G RCC Assembly Inscried T Withdrawn 7/2/4 Drivo ncd #p~ yQ)x p A:.somb!'; %/,' /,}\\ . ~ - ) r ), .i ii /J.s L F.ull Length h // ~... RCC Assembly 'j / /. m llV( i \\___.x..m L-p^y\\ t y s ) -{ sN, f,l-1 \\1 \\ i ' Guide Tubo s7 '{- 1636 03.9.- ~ . Assembly )1 \\, ~ a x f, N N e,, 4 N

g \\

.u. .n \\ Fuct Assembly H p \\s N j i U W FIGURE 1 DRIVELINE OVERVIEW

4 im S. ee, e ee me meemees Seeee9 e es. h eh m '"h ^w-8 4 g , g e g e V e e t e e 8 e 8 g g e e e e e e G e e (4,C e e e 0 e e s 6 & @ NG4 e-ee OS S OM ee@ S S W 8 6e me g 66 e FIGURE 2 FORCES EXERTED ON THE ABSORBER RODLET 1636 040 e c

%===- e mne o ee=* -

• - =

s "A 9404 e* W. e e w O o amm..amme .m &w e S

• O h

g g g O e V e i l 6 e J NNO "C b OM g J cn EW V1 in 4 J w . E' W M Z e-* "E OJW V1 s/) OCC U W CC D 4.3 m I b I e. 4 1 ! i ~ 1636 041 S e

R q,,c) i I FIGURE 4 DYtlN11C LIFT FORCE RESULTittG i FROM CROSS FLOW Ir4 THE FUEL . ASSElGLY TOP fiOZZLE 16.36 042

-~ a,e' o. t lu 1 1 i FIGURE 5 TYPICAL MEAP. SCAR III A FUEL ASSEraLY THDISLE TUSE ~ ./ f6.36 043

_ ca,c) I L t e I n I I } i I i O u c* p .c s FIGURE 6 MEASURED WAl.L THICKilESS AS A FUtiCTI0tt OF AliGULAR LOCAT10tl 0F WEAR s

t. .\\ i .. (l ~ >c) S l t L \\ t P d s m c 1 w a s u, l FIG.7. - FATIGUE CURVE FOR ANNEALED ZlRCALOY-4' SHEET MATERIAL N

y ...s~~.. 'j 17x17 Tl!It'.GLE LOCATI0liS e. (a, c ) = s ~ N e ~ ~ ~ FIGURE 8 U*lEVE;I LOAD DISTRIBUTIO!! 4.'D THIM3tE . TUBE UPPER SPAri NiD DASHPOT SPNI .g36 046 .}}