ML20140D137

Affidavit of Gr Kilp Re Contention 6.Spent Assemblies & Cladding of Fuel Rods Designed to Withstand Very High Radiation Levels Present in Reactor.Summary of Experience Encl

ML20140D137
Person / Time
Site:	Turkey Point
Issue date:	01/20/1986
From:	Kilp G FLORIDA POWER & LIGHT CO., WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:
Shared Package
ML20140C819	List: ML20140C815 ML20140C823 ML20140C831 ML20140C844 ML20140C858 ML20140C866 ML20140C878 ML20140D130 ML20140D137 ML20140D155 ML20140D181 ML20140D224 ML20140D233 ML20140D253
References
OLA-2, NUDOCS 8601290194
Download: ML20140D137 (16)

Text

._ _ __ . .- .-

,re ~ .

UNITED STATES OF AMERICA

[b l*ey [X NUCLEAR REGULATORY COMMISSION \'6 . ' q- M l} BEFORE THE ATOMIC SAFETY AND LICENSING

\'w h ..

6 b BOARD .

i. - -

l h )

In the Matter of ) Docket Nos. 50-250-OLA-2

) 50-251-OLA-2 FLORIDA POWER AND LIGHT COMPANY )

• )

' Turkey Point Nuclear Generating ) (Spent Fuel Pool Expansion)

Units 3 & 4) )

)

AFFIDAVIT OF DR. GERALD R. KILP ON CONTENTION NO. 6

1. My name is Gerald R. Kilp. I am an Advisory Engineer in the Engineering Department of the Nuclear Fuel Division of the Westinghouse Electric Corporation. My business address is Westinghouse Electric Corporation, Monroeville Mall Office Building, P. O. Box 3912, Pittsburgh, PA. 15230. A summary of my professional qualifications and experience is attached hereto as Exhibit A, which is incor-porated herein by reference.

2. The purpose of my affidavit is to address Contention 6. Contention 6 and the bases for the Contention state as follows:

8601290194 060123 PDR ADOCK 05000250 g PDR s

Contention 6 The Licensee and Staff have not adequately consi-dered or analyzed materials deterioration or failure in materials integrity resulting from the increased generation and heat and radioactivity, as a result of increased capacity and long term storage, in the spent fuel pool.

Bases for Contention The spent fuel facility at Turkey Point was originally designed to store a lesser amount of fuel for a short period of time. Some of the problems that have not been analyzed properly are:

(a) deterioration of fuel cladding as a result of increased exposure and decay heat and radia-tion levels during extended periods of pool storage.

(b) loss of materials integrity of storage rack and pool liner as a result of exposure to higher levels of radiation over longer periods.

i (c) deterioration of concrete pool structure as a result of exposure to increased heat over extended periods of time.

, In particular, the purpose of my affidavit is to address the materials integrity of the fuel assemblies and spent fuel storage racks in the spent fuel pool environment. The Affidavit of Rebecca K. Carr on Contention No. 6 and the Affidavit of Eugene W. Thomas on Contention No. 6 discuss the materials integrity of the spent fuel pool liner and spent fuel pool concrete structure. The Affidavit of Daniel C.

Patton on Contention Nos. 6 and 8 discusses the heat loads present in the Turkey Point spent fuel pools.

't

3. The remainder of this affidavit is divided into three principal parts. The first part identifies the type of materials present in the spent fuel pools and identifies the radiation and heat loads present in the spent fuel pools.

The second part discusses the materials integrity of the fuel cladding, and the third part discusses the materials inte-grity of the spent fuel storage racks.

I. Types of Materials and Radiation and Heat Loads Present in the Turkey Point Soent Fuel Pools

4. The Turkey Point spent fuel pools consist of a concrete pool structure with Type 304 stainless steel pool liner. The new spent fuel storage racks are also constructed of Type 304 stainless steel and utilize Boraflex, a neutron absorbing material. The fuel assemblies are comprised of Type 304 stainless steel, Inconel, and Zircaloy.

i 5.

As discussed in the Affidavit of Daniel C.

i Patton on Contention Nos. 6 and 8, the temperatures in the spent fuel pool could approach boiling during a loss of cooling accident. The temperature for normal conditions is not expected to exceed 143 F and will usually be less.

6. Four types of radiation (alpha, beta, gamma, and neutron) will be present in varying degrees in the spent fuel pool. For the types of material in the spent fuel pool (concrete, stainless steel, Inconel, and Zircaloy), alpha and beta radiation are not a concern because they do not have an ability to penetrate materials deeply enough to appreciably

- - . . . ._-_. ~

affect their structural integrity. Calculations were performed to determine the cumulative gamma and neutron exposures of materials present in the Turkey Point spent fuel pool for forty years. The results of these calculations indicate that the cumulative gamma dose would be 1.9 x 10 10 Rads and the cumulative neutron fluence would be 4.8 x 10 13 2

n/cm . These numbers were conservatively calculated, assuming an infinite array of storage cells each containing a spent fuel assembly.

II. Fuel Claddina Materials Intearity

7. The fuel assemblies and the cladding of the fuel rods are designed to withstand the very high radiation levels present in a reactor. The neutron fluence levels that 4

the fuel assemblies and the Zircaloy cladding are subjected to during storage in a spent fuel pool are orders of magni-tude lower than those which the assemblies and cladding experience when exposed in a reactor during full pcwer 5

operation. As a result, the total neutron fluence exposure 22 2 of the cladding is approximately 10 neutrons /cm while in 13 2 the reactor, compared to about 5 x 10 neutrons /cm during a 40 year exposure in the spent fuel pool. This difference is approximately 8 orders of magnitude. Putting it another way, the added neutron exposure after 40 years in the spent fuel pool is equivalent to approximately 1 second in a reactor at

full power. Thus, the neutron radiation levels in the spent fuel pool will have an insignificant impact on the integrity of the fuel assemblies and the fuel cladding.

8. Neutrons are the cause of virtually all of the irradiation induced changes in Zircaloy, Inconel, and the stainless steel used for the fuel assemblies. These mate-rials are essentially unaffected by the alpha, beta, and gamma radiation, which comprise the overwhelming fraction of the radiation in the spent fuel pool. In particular, although gamma radiation is a penetrating radiation, its primary effect in these materials is heating and not struc-tural damage at the levels of radiation expected in the Turkey Point spent fuel pool.

9. The fuel assemblies and fuel cladding are al,so l

designed to withstand the temperatures and heat loads present during operation in the reactor, which are far more severe than those present in the spent fuel pool. Since the zirconium used in the Zircaloy cladding is considered immune to stress-corrosion cracking in water environments like the spent fuel pool (Ref. 1), corrosion and hydriding are the only realistic threats to fuel rod cladding integrity during storage in the pool. These can be shown to be of no concern i by considering the corrosion properties of the Zircaloys used for modern light water reactor (LWR) fuel cladding.

10. At 50O degrees Fahrenheit, and at the much higher heat fluxes in the reactor, the corrosion rate of Zircaloy is approximately 1/100,000 inches per year (based upon corrosion rate equations given in References 2 and 3).

At this rate it would take over 100 years to corrode 1/1000 of an inch of cladding (compared to at least 20/1000 inch of Zircaloy wall thickness remaining when a fuel assembly is removed from the reactor for storage in the pool). This amount of corrosion would have an insignificant impact upon the structural integrity of the fuel cladding. Furthermore, at the much lower temperatures actually predicted for the spent fuel pool, the expected corrosion rate would be substantially lower. Therefore, corrosion is not expected to have any appreciable impact on the structural integrity of the Zircaloy cladding.

11. Hydriding, which at very high levels can lead to embrittlement of the cladding, is a direct function of cladding corrosion in a water environment. Since the corrosion rate is virtually nil as established above, hydriding in the spent fuel pit will be nil also.

12. Similar reasoning can be applied to the other fuel assembly components (stainless steels and Inconel) which mechanically support the fuel rods. All of these materials have been shown by test and experience to be virtuelly immune to corrosion at spent fuel pool temperatures. For example, J. R. Weeks has shown (Ref. 4) that the corrosion of Type 304 I

_-r_ _ _ _ _ _ _ _ _ _ , , . , , . , , ,_.,,,_,_.,_,_,,,,.y -- ,_,,,,_7_y .-, p g , ,_,i- _ _ _ _,, ,- 4

stainless steel will not exceed 6/10,000 inches for 100 years in an oxygenated borated water environment similar to that in the spent fuel pool. Corrosion rates for Inconel are at least as low as those for stainless steel. Additionally, since stainless steel, Inconel, and Zircaloy all form protective oxide films, no signif:. cant galvanic attack is expected among these materials.

13. The most convincing evidence that fuel assemblies do not deteriorate in the spent fuel pool comes from actual experience. Visual observations and radiation monitoring of pool water documented in a comprehensive review of light later reactor fuel behavior during pool storage by A. B. Johnson (Ref. 5), demonstrate that spent fuel has been stored safely for more than three decades. Johnson's paper also reports on the results of a number of hot cell examina-tions on fuel stored for more than ten years which show no measurable changes due to corrosion or hydriding and no loss l

of fuel integrity.

14. For- all of the above reasons, I therefore conclude that Zircaloy clad fuel and the fuel assemblies can be safely stored well in excess of 40 years in the Turkey Point Spent Fuel Pool.

l l

l l

III. Fuel Storace Rack Materials Inteority

15. The spent fuel storage racks are constructed of Type 304 stainless steel, which provides structural support, and Boraflex, a neutron absorbing material. As I have acted, stainless steel has been shown by test and experience to be virtually immune to corrosion at spent fuel pool temperatures. Similarly, the neutron radiation levels in the spent fuel pool are orders of magnitude below those levels sufficient to produce any appreciable impact upon the structural integrity of stainless steel.

1G. The neutron absorbing material, Boraflex, used in the Turkey Point spent fuel rack construction is manufac-tured by Brand Industrial Services, Inc. Boraflex is a silicone-based polymer containing fine particles of boron carbide in a homogeneous, stable matrix.

17. Boraflex has undergone extensive testing to evaluate its ability to withstand the effects of gamma and neutron irradiation in various environments and to verify its structural integrity and suitability as a neutron absorbing material. (Ref. 6). In tests performed at the University of Michigan, Boraflex was exposed to 1.03 x 10 11 Rads of gamma radiation and a total neutron fluence of 1020 neutrons /cm 2 in borated water. (Ref. 7). These tests indicate that Boraflex maintains its neutron attenuation capabilities after being subjected to an environment of borated water and radiation

--* g-- -r w- e '------r- y e a u--i-,,--r-,----- --------ww--- a,-- - - - w - --y- m - - - - -,e-, g- -- - - - -w--e- ---w+-------ei - - - - ~ - -

. _g_

13 2 and doses substantially exceeding the 4.8 x 10 neutrons /cm 10 Rads of gamma radiation anticipated for 40 year 1.9 x 10 fuel storage at Turkey Point.

18. Long-term borated water soak tests at high i

temperatures were also conducted. (Ref. 8). Boraflex maintained its functional performance characteristics and .

showed no evidence of swelling or loss of ability to maintain a uniform distribution of boron carbide. During irradiation of the Boraflex, small amounts of non-radioactive gas (N2 , 02 and CO 2

) may be generated, plus a small amount of He from neutron / boron reactions. Holes provided in the stainless 4

steel wrapper, that attaches the Boraflex to the storage cell walls, allow water to enter and gas to escape from the Boraflex. The actual tests verify that Boraflex maintains long-term material stability and mechanical integrity and that it can be safety utilized as a poison material for neutron absorption in spent fuel storage racks.

19. Based on the material properties of Type 304 i stainless steel and the rigorous testing of the Boraflex neutron absorber material, I am confident that the spent fuel racks will maintain their material integrity under the conditions expected in the spent fuel pools for Turkey Point.

i

_ 10 _

IV. Conclusion i

20. The spent fuel assemblies and fuel cladding are designed to withstand the radiation and heat loads in the reactor. These conditions are far more severe than those present in the spent fuel pool. Tests and experience have shown that no significant deterioration of the materials used in cladding and assemblies occurs in a spent fuel pool environment. Therefore, the fuel cladding and assemblies are l

expected to maintain their structural integrity during storage in the Turkey Point spent fuel pool. Similarly, the materials in the spent fuel storage racks are expected to maintain their integrity while in the Turkey Point spent fuel pool.

i

~

FURTHER AFFIANT SAYETH NOT The foregoing is true and correct to the best of my knowledge, information and belief.

d .

Gerald R. Kilp "

STATE OF PENNSYLVANIA )

COUNTY OF ALLEGHENY )

Subscribed and sworn to before me this 70 day of , 1986. My commission expires /#/d/87

/ r h ft

• A NOTARY PUBIfIC LORRAINE M. PlfLiCA. N07EI PUBlic MONR3EVILLE BORD. ALLEGt:IfiY COUr TY MY COMMISSION EXPIRES CEC 14,1987 Member. Pennsylvania Association of Notanes

r HEEEEENCES

1. Douglas, D. L., "The Metallurgy of Zirconium," Fublished by the International Atomic Znergy Agency, Vienna, 1971 Supplement, page 363.

t

2. Dalgaard, S. B., "Long Term Corrosion and Hydriding of Zircaloy 4 in Commercial Pressurized Reactors with Forced Convective Heat Transfer", presented at the Electrochemical Society, Inc., May 2-7, 1976, Page 1.

3. Garzarolli, F., Jorde, D., Manzel, R., Parry, P. W. and Smerd, P. G., " Review of PWR Fuel Rod Waterside Corro-sion Behavior," EPRI NP-1472, August 1980, Section 2.0.

4. Weeks, J. R., " Corrosion of Materials in Spent Fuel Storage Pools," BNL-NUREG-23021, July 1977.

5. Johnson, A. B., " Behavior of Spent Nuclear Fuel in Water Storage," BNWL 2256, September, 1977.

6. Anderson, J. S., "Boraflex Neutron Shielding Material --

Product Performance Data," Brand Industries, Inc.,

L Report 748-30-2 (August 1981).

l o

7. Anderson, J. S .' , " Irradiation Study of Boraflex Neutron Shielding Materials," Brand Industries, Inc., Report 748-10-1 (August 1981).

8. Anderson, J. S., "A Final Report on the Effects of High Temperature Borated Water Exposure on BISCO Boraflex Neutron Absorbing Materials," Brand Industries, Inc.,

Report 748-21-1 (August 1978).

I 1

_ 14 _

EXHIBIT A ,

STATEMENT OF PROFESSIONAL QUALIFICATION OF GERALD R. KILP I

My name is Gerald R. Kilp. My business address is Westinghouse Electric Corporation, P.O. 3912, Pittsburgh,

• Pennsylvania, 15230. I am an Advisory Engineer for the Product Engineering Section of the Westinghouse Nuclear Fuel Division, Westinghouse Electric Corporation. I have served in this function since November, 1983. In this capacity, I am responsible for selected Materials Development programs and act as a general advisor on materials performance questions for the Westinghouse Nuclear Fuel Division.

I graduated from Missouri Valley College, Marshall, Missouri, in 1952 with a Bachelor of Science degree in Chemistry. In 1957, I received a Doctorate of Physical Metallurgy from Iowa State College (since renamed to Iowa 1

State University).

From 1952 to 1957, I was a Graduate Assistant at the Ames Laboratory for Atomic Research, an AEC supported laboratory at Iowa State College. During this period, I j worked on binary phase diagrams and evaluated methods for protection of uranium metal from water corrosion.

i 1

From December, 1957 to May, 1962, I was a Senior Engineer and, later a Fellow Engineer, at the Westinghouse Atomic Power Department where I worked on thermoelectric and thermionic materials for application in nuclear reactors.

In May, 1962 and until September, 1968, I acted as supervisor and later Manager of Fuel Evaluation on the NERVA Reactor Project at the Westinghouse Astronuclear Laboratory at Large, Pennsylvania. In September, 1968 and until May, 1972, I served as the Engineering Manager of the Astronuclear Fuel Facility at Cheswick, Pennsylvania. In this capacity, I was responsible for process development for fabrication of NERVA reactor fuel as well as reactor fuel performance evaluation.

In May, 1972, I transferred to the Westinghouse Nuclear Fuel Division of Westinghouse Nuclear Energy Systems, in Monroeville, Pennsylvania. From then to May, 1980, I served as the Manager of Materials Design. This group had the basic responsibility for materials R&D, and approval of materials for use in Westinghouse Pressurized Water reactors.

The duties further included determination of the necessary and sufficient requirements for reactor coolant and pool storage chemistries needed to ascure satisfactory performance under all warranted conditions. All reactor and out-reactor corrosion testing evaluations were done under the cognizance of this group.

t From May, 1980, and until November, 1983, I worked at the Westinghouse Advanced Energy Systems Division where I served as the Manager of Materials Interactions until November of 1983. These activities were primarily concerned with addressing materiale selection and evaluation for application in long term storage of light water reactor fuel in underground and above ground facilities.

Since 1979 I have also been a member of the American Society for Testing and Materials (ASTM) C26 Committee on the Nuclear Fuel Cycle. At the present time I am the Chairman of Sub-committee C26.02 (Fuel and Fertile Materials Specifications) and serve on C26.03 (Neutron Absorber Materials Specifications).

1

. - _ .