ML19260D829
| ML19260D829 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 01/23/1980 |
| From: | Richard Anderson AFFILIATION NOT ASSIGNED |
| To: | |
| Shared Package | |
| ML19260D824 | List: |
| References | |
| NUDOCS 8002120471 | |
| Download: ML19260D829 (14) | |
Text
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD IN THE MATTER OF
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COMMONWEALTH EDISON CO.PANY
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Docket Nos. 50-295
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50-304 (Zion Station Units 1 and 2)
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Proposed Amendments to
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Increase Spent Fuel Storage
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Capacity (4 3 F.R. 30938)
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AFFIDAVIT OF ROBERT ANDERSON I,
ROBERT ANDERSON, being first duly sworn and under oath, certify that the statements contained in the attached pages and accompanying exhibits are true and correct to the best of my knowledge and belief.
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n Wu w SUBSCRIBED AND SWORN TO BEFORE ME THIS Q
DAY OF,
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1980.
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" NOTARY PUBLIC 1949 289 My commission expires b
19d MARIAN L WHITE
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g* My Commission Expires May 7,1982
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hi?IDAVIT OF ROBERT ANDERSON As my resume attached to my December 17, 1979 Affidavit details, I am a chemical metallurgist:
I study the reaction of materials in a chemical environment and the chemistry of the materials themselves.
One of my areas of specialization in this field is corrosion and materials failure due to corrosion.
I have done considerable consulting work in this area, including work on stress corrosion problems of stainless steel, aluminum, and copper,and I teach graduate level courses on corrosion.
I hold approximately thirty foreign and domestic patents in nuclear fuel reprocessing and reactor design.
In addressing the Board's Questions I have also drawn upon my education and experience in the field of fluid mechanics.
I studied fluid mechanics in undergraduate and graduate courses at the University of California at Berkeley.
For seven years I designed and modeled fluid systems as a research Chemical Engineer in the United States Navy.
My Navy research included _he study of stagnant and flowing fluid systems and their effec:s on surface phenomena.
I have taught graduate courses in fluid mechanics; I now teach a graduate course that covers the effects of fluiu dy-namics on corrosion rates.
i949 290 In addition to the documents listed in my December 17, 1979 Affidavit, I have reviewed Applicant's Exhibit 5 (NSC blue-print of the proposed tube design), Applicant's Exhibit 3 (portions of the Zion FSAR), the written and oral testimony presented at the hearings in this proceeding of Messrs.
Johnson, Draley, Clark, Mollerus, Hossain, Olson, Almeter, and Lantz, and Applicant's Exhibit 4 (Licensing Report).
QUESTION 1:
Whether the water in the pool would be a " stagnant, oxygenated, borated water system" as defined by the NRC Staff on page 3 of the I.E.
Bulletin No.79-17, Revision 1.
The NRC definition of " stagnant, oxygenated borated water system" contained in I.E.
Bulletin No.79-17, Revision 1, Page 3 requires that three elements be present.
1)
Air saturation of the water 2).
Borate dissolved in the water 3).
No continuous dynamic flow Barring chemical manipulation to prevent saturation, we must expect that in an open pool such as the Zion spent fuel pool the saturation of the water with oxygen will occur.
In addition, any increase in temperature above the ambient level will tend to insure saturation.
When a spent fuel assembly is placed in the pool the temperature of the surrounding water will increase, moving any unsaturated water closer to saturation.
The open pool and 1949 291 These temperature increases eO.e it likely, in my opinion, that the condition of air saturation will exist throughout the pool.
The Staff definition states that borate must be present.
This is true in all water entering the pool, and there appears to be no mechanism within the pool to de-borate any part of the water.
The final condition requires no continuous dynamic flow.
This definition of " stagnant" is imprecise.
In fluid dynamics,
" stagnant" is usually defined as zero flew.
Other flou conditions are described as laminar or turbulent and classified by a Reynolds number, which precisely quantifies flow, relating flow rate to turbulence in the fluid.
To assess accurately the flow condition in the Zion spent fuel pool would require detailed knowledge and modeling of the flow path of the water through the racks and the effect of loading individual fuel storage tubes with fuel assemblies.
The information available in this proceeding allows only a qualita-tive description of flow in the pool.
On the basis of the information presented, it appears likely that there will be "no continuous dynamic flow" in some areas of the pool.
A volume equal to all the water 2.1 the pool is exchanged every five hours (Tramm Nov.1979 Affidavit, p. 4).
The flow rates over the surface of the stainless steel will vary throughout the pool due to the tendency of the fluid to take the path of least resistance.
As a result of this channeling, some areas will have significantly higher flow rates than others, and there may be blind areas having no flow at all.
Consequently, this
!949 797 short circuiting of the water pathway through the pool will allow stagnant areas to exist.
A second flow mechanism, convection, will be caused by the heat of the fuel assemblies, and may tend to lessen stagnant conditions.
Convection will be least for unoccupied racks.
It will be greatest, tending to lessen stagnant conditions, near racks containing fresh fuel assemblies.
Given these flow mechanisms, each area of stainless steel / water interface may be evaluated for flow /no flow conditions.
Table 1 summarizes the general expected flow conditions for the four types of welded stainless steel / water interfaces and the two conditions of filled and unfilled racks.
As Table 1 illustrates, there can be stainless steel / water contact areas in the Zion spent fuel pool that are non-flowing and, hence, stagns within the definition of NRC Staff.
Since certain areas of the pool may be stagnant within the definition of the NRC, I recommend that the Applicant be re-quired to undertake a study to identify potential stagnant areas, and present a plan for rack inspection, repair, or replacement, as I shall describe in greater detail below.
1949 293 QUESTION 2:
Whether the water inside the pro-posed vented fuel storage tubes would be a
" stagnant oxygenated borated water system,"
and if so, what would be the effect on the fuel storage tubes and racks.
Tom Tramm stated on page 5 of his November 1979 Affidavit that because there would be no convective flow path within the spent fuel storage tube walls, any water within the stainless steel sheaths is expected to be stagnant.
A review of Applicant's Exhibit 5 (Nuclear Services Corp. blueprint ~no.1000502, Revision C) further supports the conclusion that water within the tube walls will be stagnant.
The mechanisms that would allow circula-tion of water inside the tube walls will have an insignificant effect on flow.
The blueprint shows that four 0.25 inch diameter holes will be drilled in the top of the inner sheath of each tube.
It is r.ot clear whether these holes can actually function to vent the inside of the stainless steel sheath.
The blueprint indicates that they may penetrate only through the fusion welded area above the Boral, and may not reach down into the Boral sandwich unless the fusion weld is ruptured, for example, by a gas evolution reaction.
Assuming that the holes were functional vents, their area would nonetheless be too small to create a continuous exchange of water between the outside pool environment and the approximately 158-inch long interior of the sheath.
1949 294 Some stirring may occur, due to heat convection and the gas-producing neutron reaction with boron, in a vented tube in-terior when the rack contains a spent fuel assembly.
- However, the geometry of the space within the sheath that can hold water is so thin and flat that it is improbable that stirring could have a significant effect on flow in that space.
Since the water in the sheath will be stagnant, and since the water is also oxy-genated and borated, all three of the fluid prerequisites for IGSCC are present in the water.
A significant material requirement - stress - is also satisfied.
In addition to the stress caused by welding, there will be thermal stress and mechanical stress caused by the loading and weight of the fuel assemblies.
Reactions due to radiation can damage the metal structure of the stainless steel, increasing further its tendency to corrode.
The carbon content in stainless steel also acts as a stress producing element, increasing corrosion potential. Intergranu-lar stress corrosion cracking will develop more slowly in stainless steel with a low carbon content (such as the.03.04 percent carbon steel in the tubes) than a steel with a higher carbon content in the same environment.It is,nonetheless, possible for IGSCC to occur over time in relatively low carbon steel.
Since there is no exper-ience with racks like these for a period comparable to their expected forty year life, one cannot predict how severe IGSCC may become over the life time of the racks.
1949 295
- In conclusion, under the combined condition of mechanical and thermal stress, and oxygenated borated stagnant water, the heat affected zones of the fusion welds at the top and bottom of each tube may undergo IGSCC.*
This mechanism can result in a number of welded areas failing.
The spent fuel rack system appears structurally to be very well designed.
However, if IGSCC affects structural welds, the structural integrity of the racks may be threatened.
Since IGSCC may under pool conditions affect structural welds, it is in my opinion necessary that the Applicant provide the Board with an adequate IGSCC inspection and repair program that would remain in effect throughout the life of the racks.
The coupon inspection program referred to in Roger Staehle's November 16, 1979 Affidavit is inadequate as presented.
Any samples used in an inspection program must truly represent all the various environments and conditions of the functioning racks in the pool, i.e. with and without fuel assemblies present, and with exposed and hidden surfaces.
1949 296 In addition, the galvanic reaction of the aluminum, described in the Affidavit of John R. Weeks, p.2, could operate to some extent.
Weeks suggests that the galvanic reaction will pro-tect the stainless steel sheath from corrosion.
To protect the steel the galvanic corrosion of aluminum would have to be con-tinuous and extensive throughout the life of the racks.
Corro-sion at such a rate might destroy the aluminum and allow redistri-bution of boron.
However, galvanic corrosion will be neither extensive nor continuous (and, therefore, will not protect the stainless steel) throughout the life of the rack.
Under the existing pool temperature and pressure conditions, one can expect that a film of corrosion product will build up on the aluminum, preventing the galvanic mechanism from operating.
An adequate inspection and repair program must include the following:
1.
All welds that are important to the structural integrity of the racks, should be identified; and criteria should establish the crack size that will require corrective action and the nature of the corrective action (repair or replacement) for cracks in different locations.
2.
Visual inspection every five years of all structural welds on a specific rack assembly that is used in the pool.
The inspected rack must be one that has fuel stored in it (except during the inspection).
3.
If there is a question whether cracking may have oc-curred in an area, that area must be subject to penetrant examina-tion.
4.
If questionable areas remain after penetrant examin-ation, those areas must be cut out and examined metallurgically.
5.
If examinations reveal any cracks in structural welds, then all other racks in the pool must be examined following this procedure.
1949 297 6.
Any racks having cracks in structural welds that meet the established crack size criteria must be repaired or replaced.
Additionally, I recommend that the Applicant store one or two extra rack assemblies near the spent fuel pool at all times, in the event one would be needed for replacement.
1949 298
TABLE 1
Principle flow conditions across stainless steel / water interface Water / Steel Interface Location
- Not Loaded Loaded With Fuel Assembly Outside of tube Forced / stagnant Forced / convection Inside of tube Forced flow Convection Inside of SS sheath Stagnant Probably stagnant SS Pool liner Forced flow Forced flow Refer to figure 1.
1.
Certain exposed steem areas will probably have pool water forced flowing by them while non-exposed areas will probably be in con-tact with stagnant water.
2.
Exposed areas will be in contact with forced flowing water while non-exposed areas will probably be in contact with pcol water stirred by convection.
1949 299
RACK BASE I
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Figure 1.
Schematic of Spent Fuel Pool Tube, Base and Pool Liner.
1949 300
PROOF OF SERVICE I, MARY ANN WOZNIAK, having been sworn and under oath do state that I have this 24th day of January, 1980 served a copy of the foregoing Submission Of The State Of Illinois In Response To Order Of January 8, 1980, and Affidavit of Robert Anderson, upon Michael Miller, Esq., Philip P. Steptoe, Esq., Isham, Lincoln,
& Beale, One First National Plaza, Chicago, Illinois 60690, by hand delivery, and upon the following:
John Wolf, Chairman, Atomic Safety & Licensing Board, U.S.
Nuclear Regulatory Commission, Washington, D.C.
20555; Dr. Forrest J.
Remick, 305 E.
Hamilton Avenue, State College, Pennsylvania, 16801; Dr. Linda W. Little, 5000 Hermitage Drive, Raleigh, N.C. 27612; Atomic Safety & Licsqsing Appeal Board Panel, U.S. Nuclear Regula-tory Coamission, Washington, D.C.
20555; Atomic Safety & Licensing Board Panel, U.S. Nuclear Regulatory Commission, Washington, D.C.
20555; Richard Goddard, Esq., Steven Goldberg, Esq., Office of the Execu-tive Legal, Director, U.S. Nuclear Regulatory Commission, Washing-ton, D.C. 20555; Mr. Rick Konter, 617 Piper Lane, Lake Villa, Illinois 60064; Docketing & Service Section, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, by placing same in an envelope addressed to said persons, first class postage prepaid, and depositing it 1949 'O' with the United States Post Office, located at 160 North LaSalle Street, Chicago, Illinois 60601.
SUBSCRIBED AND SWORN TO BEFORE ME THIS 24TH DAY OF JANUARY, 1980.
NOTARY PUBLIC 1949 302