ML20129F182
| ML20129F182 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 09/27/1996 |
| From: | Alexion T NRC (Affiliation Not Assigned) |
| To: | Hutchinson C ENTERGY OPERATIONS, INC. |
| References | |
| IEB-96-004, IEB-96-4, TAC-M96321, TAC-M96322, NUDOCS 9610010275 | |
| Download: ML20129F182 (5) | |
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4 September 27, 1996 Mr. C. Randy Hutchinson Vice President, Operations ANO Entergy Operations, Inc.
1448 S. R. 333 Russellville, AR 72801
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION PERTAINING TO NRC BULLETIN 96-04, ARKANSAS NUCLEAR ONE, UNITS 1 AND 2 (TAC NOS. M96321 AND M96322)
Dear Mr. Hutchinson:
The Nuclear Rgulatory Commission (NRC) staff is continuing its review of the Entergy Operations, Inc. response to Bulletin 96-04, " Chemical, Galvanic, or Other Reactions in Spent Fuel Storage and Transportation Casks." The enclosure to this letter contains another request for additional information.
Please respond to this request by letter.
If necessary, the NRC staff is available for additional discussions of issues related to the bulletin.
Sincerely, Original signed by Thomas W. Alexion, Project Manager Project Directorate IV-1 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket Nos:
50-313 and 50-368 Enclosurei Request for Additional Information cc w/ encl:
See next page DISTRIBUTION:
1 Docket File PUBLIC PD4-1 r/f E. Adensam (EGA1)
P,-Trestleryd-T. Alexion W. Beckner (WDB)
J. Roe OGC ACRS J. Dyer, RIV Document Name: AR96321.RAI 0FC PM/PB0h'lA/PD4.-/
NAME IAlebhh (PTNs"ler i
DATE N/M/96 C/ /8/96 COPY
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WASHINGTON, D.C. anana annt September 27, 1996 Mr. C. Randy Nutchinson Vice President, Operations ANO Entergy Operations, Inc.
1448 S. R. 333 Russellville, AR 72801
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION PERTAINING TO NRC BULLETIN 96-04, ARKANSAS NUCLEAR ONE, UNITS 1 AND 2 (TAC NOS. M96321 AND M96322)
Dear Mr. Hutchinson:
The Nuclear Rgulatory Commission (NRC) staff is continuing its review of the Entergy Operations, Inc. response to Bulletin 96-04, " Chemical, Galvanic, or Other Reactions in Spent Fuel Storage and Transportation Casks." The enclosure to this letter contains another request for additional information.
Please respond to this request by letter.
If necessary, the NRC staff is available for additional discussions of issues related to the bulletin.
Sincerely, GJ Rd j&
Thomas W. Alexion, Proje Manager Project Directoratc IV-1 Division of fieactor Projects III/IV Office of Nuclear Reactor Regulation Docket Nos: 50-313 and 50-368
Enclosure:
Request for Additional Information cc w/ enc 1: See next page t
Mr. C. Randy Hutchinson Entergy Operations, Inc.
Arkansas Nuclear One, Units 1 & 2 cc:
Executive Vice President Vice President, Operations Support
& Chief Operating Officer Entergy' Operations, Inc.
Entergy Operations, Inc.
P. O. Box 31995 P. O. Box 31995 Jackson, MS 39286-1995 Jackson, MS 39286-199 Wise, Carter, Child & Caraway Director, Division of Radiation P. O. Box 651 Control and Emergency Management Jackson, MS 39205 Arkansas Department of Health 4815 West Markham Street, Slot 30 Little Rock, AR 72205-3867 Winston & Strawn 1400 L Street, N.W.
Washington, DC 20005-3502 Manager, Rockville Nuclear Licensing Framatone Technologies 1700 Rockville Pike, Suite 525 Rockville, MD 20852 Senior Resident Inspector U.S. Nuclear Regulatory Commission P. O. Box 310 4
London, AR 72847 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 County Judge of Pope County Pope County Courthouse Russellville, AR 72801 4
d
6*
REQUEST FOR ADDITIONAL INFORMATION ON ARKANSAS NUCLEAR ONE'S RESPONSE TO NRC BULLETIN 96 04 6
Information Reauested Demonstrate that the 21rcaloy cladding will be protected during storage l
against degradation that leads to gross ruptures or that the fuel is otherwise confined such that degradation of the fuel will not pose operational safety problems with respect to the removal of the fuel from storage
[5'2.122(h)(1)].
Storage conditions over the 20-year licensed period should be considered in this evaluation.
Provide pertinent data and analyses to supDort your conclusions. such as:
data on the diffusivity of zinc (or a reasonable estimate) in the e
grain boundaries (9.b.) of Zircaloy at the appropriate storage temperatures. or other data that could lead to a reasonable conclusion that the extent of 9.b. diffusion over a 20-year storage period 1s loc Information about reaction rate kinetics that support the position tha*. no s1gnificant amount of reaction between zinc and Z1rcaloy will occur over the approved 20 year storage period, at the appropriate partial pressure of zinc:
Information about the effect of zinc on the properties and behavior of 21rcaloy either when it is present in the matrix, or more 1mportantly, in the grain boundary.
an evaluation of the potential for corrosion along grain boundaries.
cracking in the grain boundaries, and loss of ductility or strength.
and for any likely effects, a discussion on the implications for posing operational safety problems with respect to the removal of the fuel from storage: and a justification of the applicability of the zinc-injection test data e
(EPRI TR-104702) to dry storage conditions.
Bases for the Recuest The staff is concerned about the potential for degradation that leads to gross rupture of the fuel cladding due to diffusion of zinc in the grain boundaries of Zircaloy. The Entergy submittals (by facsimiles) dated September 12,19.
and 20. 1996. do not sufficiently address grain boundary diffusion, the properties of Zircaloy containing zinc. and the potential consequences with respect to fuel clad integrity as discussed below.
Calculations were made on the diffusion of zinc through zirconium using a single va}/s at 826*C. from Smithells Metals Reference Book.
ue of the diffusivity of zinc in zirconium (D - 2.8 x 1022 cm-ENCLOSURE
sixth edition). This diffusivity value apparently represents lattice diffusion. Based on extrapolation of this value and without knowing the activation energy, calculations were made to show that zinc will penetrate only microns through the Zircaloy clad by lattice diffusion at dry storage temperatures.
However, there are cases in which the postulated diffusion along the g.b. may be several orders of magnitude higher along the g.b.
Because D(lattice) decreases much faster with temperature than D(g.b.), the ratio D(g.b.)/D(lattice) increases rapidly as temperature decreases (Refs. 1, 2 and 3).
An equilibrium diagram of zinc and zirconium was used to conclude that no reactions would occur between these two metals until the temperatures at the eutectoid temperature are obtained. The diagram indicates that at low concentrations of zinc the equilibrium phases that tend to form between zirconium and zinc are alpha zirconium, where the solubility is believed to be low for zinc but has not been measured, and the intermetallic phase ZnZr which would form in proportion to the location on the diagram.
Further, the temperatures of interest, for dry storage conditions, are near the melting point of zinc and the eutectic between zinc and zirconium.
This is an indication that. being near its melting point. the reactivity of zinc could be relatively high and the formation of intermetallic phases may be possible in short times.
In absence of appropriate diffusion data to the contrary, the staff cannot yet conclude that the kinetics are too slow for the formulation of ZnZr at the temperatures in question (Refs. 4 and 5).
Although zinc-injection tests were performed on BWR systems (EPRI TR-104702). it is not clear how the data from these tests pertain to conditions inside the MSB during dry storage, where the zinc levels may be four orders of magnitude higher and the cladding temperatures could be 700*F to 800*F.
References 1.
Lobnig. R., H. Schmit. K. Hennesen and H. Grabke.
Diffusion of Cations in Chromia Layers Grown on Iron-Base Alloys 1992. Oxidation of Metals, vol. 37. 81.
- 2. Whittle. D.. Y. Shida. G. Wood. F. Stott and B. Bastow. Enhariced Diffusion of Oxygen during Internal 0xidation of Nickel-Base Alloys.
1982. Phil. Mag.. vol. 46. 931.
3.
Verhoeven. Hohn D.
" Fundamentals of Physical Metallurgy." John Wiley and Sons 1975. Chapter 6 (p. 155) (TN690.V46).
4.
Reed-Hill Robert E., and Reza Abbaschian. " Physical Metallurgy Principles." PWS Publishing Co.
Boston. Third Edition. 1994.
Chapter 12 (TN690.R43).
5.
Porter. D. A. and K. E. Easterling. " Phase Transformations in Metals and Alloys." Van Nostrand Reinhold Co. Ltd. 1981 1st Edition.
Chapter 5
" Diffusion Transformations in Solids" (TN690.P597).
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