ML19209B857
| ML19209B857 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 09/24/1979 |
| From: | Reid R Office of Nuclear Reactor Regulation |
| To: | Groce R YANKEE ATOMIC ELECTRIC CO. |
| References | |
| NUDOCS 7910110057 | |
| Download: ML19209B857 (5) | |
Text
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NUCLEAR REGULATORY COMMISSION f
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Septerter 24, 1979 Docket No.: 50-309 Mr. Robert H. Groce Licensing Engineer Yankee Atomic Electric Company 20 Turnpike Road Westboro, Passachusetts 01581
Dear Mr. Groce:
Control Element Assembly (CEA) guide tube wear has been an issue at Maine Yankee as well as other pressurized water reactors. The aoparent cause of this wear is flow induced vibration of the CEA's. Sleeves have been installed at Maine Yankee to preclude guide tube wear and test fuel assem-blies have been installed as part of a program to minimize CEA vibrations.
These actions have been taken with Combustion Engineering fuel in the core.
You have indicated that Exxon fuel will be put in the core for the next reload.
It is necessary that the CEA guide tube wear issue be addressed for the Exxon fuel.
In addition the flow induced vibration of the CEA's has raised the concern of what effect this vibration has on the CEA's.
To address these areas you are requested to provide the infomation in the enclosure before or with your upcoming reload submittal.
Sincerely, 2dVZJ Robert W. Reid, Chief Operating Reactors Branch #4 Division of Operating Reactors
Enclosure:
Infarration Request cc w/ enclosure: See next page
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7910110 t
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Yankee Atemic Electric Company cc:
E. W. Thuricw, President Mr. Robert R. Radcliffe flaine Yankee Atonic Power Company Office of Energy Resources 9 Green Street 55 Capitol Street Augusta, flaine 04330 Augusta, Maine 04330 fir. Donald E. Vandenburgn Vice President - Engineering Yankee Atonic Electric Company 20 Turnpike Road Westboro, flassachusetts 01581 John A. Ritsher, Escuire Ropes and Gray 225 Franklin Street Boston, Massachusetts 02110 9
fir. John it. R. Paterson Assistant Attorney General State of Maine Augusta, Maine 04330 f
Mr. Nicholas Barth Executive Director Sheepscot Valley Conservation Association, Inc.
P. O. Box 125 Alna, Maine 04535 Wiseasset Public Library Association High Street Wiscasset, ffaine 04578 Mrs. L. Patricia Doyle, President SAFE POWER FOR MAINE i
Post Of fice Box 774 Cancen, fiaine 04843 3
11 ~0 163
1 INFORMATION RE00EST The items cetailed in this attachn.ent are accressec primarily at the capaoility of the reloac fuel cesign to mitigate the guice tube wear that was observec in the CE NSSS facilities. The overall capability of the reloac fuel to perform its imtenced structural, thermal-hycraulic, physics, anc power generation functions is oeycnc the intenced scope of this attachment. However, since some of the reloac fuel design features to mitigate guice tube wear may effect other aspects of the fuel design capabilities, scoe, overlap into reload areas is unavoicaole.
i It is our understancing that tne reloac fuel design will use sleeves in the upper section of the guice tuoes to function as more resistant wear surfaces.
This cesign feature is similar to thct usec by Comoustion Engineering as an interim mocifica. tion.- Please note that CE attributes guide tube wear to flow-incucea vibration of the Control Element Assemolies (CEAs). Sleeving the Control Roc buice Tuoes (CRGTs) is not expectec to eliminate v1 oration of the CEAs. In regarc to vibration of the CEAs, CE has performed loop-flow tests anc installed a numoer of flow-modifying test assem; lies in specific CE cesignec plants. The results of these tests are not yet complete. How-ever the flow-mocifying test assemolies are cesigned to eliminate or to recuce the flow-incucea vibration of the CEAs.
Since current sleeving designs have not eliminated or reduced vibration of the CEAs, the long term vibration effects of the CEAs should oe considerec.
Accress the following items before or in your plannec reloac submittal. An early suomittal of tnis information will expecite the completion of our review.
A.
Design Information Provice detailec crawing of the proposec reload fuel cesign. In particular cescrioe anc ciscuss tnose components and principles used in the reloac fuel cesign to mitigate guice tuce wear anc vibration of tne Control Element Assemoly (CEA).
B.
Test Data 1.
Provice information on any out-reactor, loop-flow prototype testing of the reload fuel cesign. This information may include results of flow visual-ization tests, thermal-hycraulic flow tests, and flow-incucea viDration of tne CEAs. Discuss the results, conclusions, anc correlations ootainec from tnese tests.
2.
Provice information on any in-reactor cemonstration assemolies that verifies the wear performance characteristics of the reloac fuel cesign. Discuss, anc compare, tne performance of the in-reactor test assemolies witn tne prototype test assemolies anc tne current CE-cesignec tuel assemolies.
300RORGR1 lO 164
' 3.
Items 1 and 2 should include details of any examinations performed such as:
(a) Metnods of examinat' ions i.e.:
destructive, eddy current, peri-scope, bores: ope, mechanical gage, metallographic, flow visualization, T.V.
(D) Areas of fuel assemoly and guide tubes examined.
(c) Results of examinations.
(d) Numoers of samples in each data base including operations parameters sucn as: core location, Effective Full Power Hours, time in service under CEAs, neutron fluence, coolant flow, thermal cycles, and any other related core parameter.
(e) Qualification of test procecures.
4.
Provice all correlations supportea by your tests relative to guide tube wear during reactor operations over the reactor life of the reload fuel.
5.
Provide information on control rod scram tests that demonstrate CEA scramability for the reload fuel design. Address degraded scram-ability over the reactor life of the reload fuel.
Include any strain, deflee. tion, or time limits on control rod functions.
C.
Analysis 1.
Provide information anc your evaluation of the chemical compatability between tne sleeving and the CRGT. This evaluation should include consideration of corrosion product buildup, and coolant boiling in the annulus oetween the sleeving and the guice tubes.
2.
Provice the results of your structural analyses summarizing tne CRGT loacs anc tne primary and seconcary stress intensities for normal operation fuel handling, and accicent loading conditions. The analyses should clearly cemonstrate that a coolable geometry is maintained for all loading concitions, and that scram capability of the control rocs is not impaired beyonc "acceptacle limits." Provide ano discuss the cetermination of these " acceptable limits."
3.
Discuss your structural design bases and the allowable stresses usec in the structural analysis. Indicate what provisions have been mace to account for wear in the design, anc what amount of wear woula De lO 165
. unacceptable. Discuss the propensity for hydrogen uptake in the guide j
tubes as a function of wear. Discuss the effects of notch sensitivity, irradiation haroening, hydrogen content of the Zircaloy, and thermal cycling, on the analysis. Discuss any differential thermal expansion or stress relaxation between the sleeving and the guide tubes. How does this relaxation effect the design and operational performance?
r 4.
Discuss any administrative, or operational procedures indicated prudent, or necessary, by your analyses.
D.
Fuel Surveillance Provide details of a planned surveillance program (see item B.3) for the next and future end-of-cycle outage and your commitment to carry out this program. We request that this procran be submitted for NRC e
review before implenentation. The fuel surveillance program should assure that the existing and reload fuel performs in accordance with design.
E.
CEA Surveillance You are requested to propose a CEA surveillance program which should include examinations and evaluations of the CEAs because of their continued vibration. The CEA surveillance progran may include examinations addressed at identification of fatique cracking, stress corrosion cracking, abrasion, denting, poison material degradation (compaction, and leakage), and other phenomena which could inpede their movement, degrade their design function, or reduce their design life.
F.
Limits of Dearadation Specify the acceptance criteria, to be used in your surveillance pro-grams, for continued use of the existing fuel, reload fuel and the C EAs. Justify the basis upon which these criteria have been determined.
Specify the acceptance for repaired fuel and discuss the repair procedures. Specify the rejection criteria to discontinue the use of the fuel and the CEAs.
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