ML20033A931
| ML20033A931 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 11/23/1981 |
| From: | CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| References | |
| ISSUANCES-OLA, NUDOCS 8111300176 | |
| Download: ML20033A931 (9) | |
Text
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RELATED C0"2Z5FONDENCE COC KETED I-mc e e r u t._ n:
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'81 NOV 23 PS:10 STATEMENT OF MATERIAL FACTS
' SECRETARY
'S & SERV!CC
- U:CH A.
THE CONTENTION The corrosion and degradation of the materials of construction of the pool, pool liner, fuel elements, and racks (for example, a
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concrete, stainless steel, and
' ' /,5 aluminum) will be accelerated n;. Af s
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I and racks will not retain theirCj % g,[?
sion and, as a result, the pool l',
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w integrity through the remaining Q
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term of the operating license.
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B.
MATERIAL FACTS AS TO WHICH THERE IS NO GENUINE ISSUE TO BE HEARD 1.
The increased heat resulting from expansion of the spent fuel pool will be minimal. (Affidavit of Daniel A.
Prelewicz, p.
2-3).
2.
Following a full core offload, maximum fuel pool temperature would be 101 F for the expanded pool, i
l compared to 99 F for the present pool; for the l
normal refueling sequence, maximum pool tempera-ture would be 93 F for the expanded pool, as compared with 88 F for the present pool.
(Affi-I davit of Daniel A.
Prelewicz, p.
4).
3.
(a)
The corrosion rate of Type 304 stainless steel, the material of the new racks and the 3
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8111300176 811123 PDR ADOCK 05000 G
i i pool liner, in demineralized water at temperatures of 450 F to 572 F is less than 0.0001 inch per year.
(b)
At the low temperatures of the expanded Big Rock Point spent fuel pool, it is highly unlikely that the corrosion rate of this material would be detectable;.and in any case the increase of 2 F to 5 F caused by pool expansion would have no measurable effect on I
this corrosion rate.
(c)
The corrosion rate of the new racks will be insignificant, and the pool liner corrosion rate will not be accelerated by the pool expansion.
(Af fidavit of A.
John Birkle at p.
3).
i 4.
Although a water temperature of 300 F to 400 F increases the susceptibility to stress-corrosion cracking of Type 304 stainless steel, such cracking will not be accelerated by the maximum 101 F l
temperature resulting from the expansion of the I
spent fuel pool.
(Af fidavit of A. John Birkle at
- p. 4).
I 5.
(a)
In demineralized water at temperatvxes of 122 F to 200 F, the cumulative corrosion for
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. aluminum alloys such as that used in the existing spent fuel racks would he less than 1.0 mil over a 20-year period.
(b )
Because the minimum thickness of the aluminum spent fuel racks at Big Rock is 250 mils and the pool temperature will not exceed 101 F after expansion, the general corrosion rate for the racks is negligible.and the difference due to the temperature rise is even more insignificant.
(Af fidavit of A.
John Birkle at p. 5).
6.
The corrosion rate of Zircaloy cladding is.0002 mils per year in a water temperature of 932 F; at the maximum 101 F temperature of the expanded Big Rock Point spent fuel pool, the rate of corrosion is negligible and the effect on this rate of the temperature rise resulting from pool expansion is equally insignificant.
(Affidavit of A. John Birkle at p.
5-6).
7.
(a)
The maximum increase of 5 F will cause a slight expansion in the aluminum materials of the existing spent fuel racks, but no stresses to the racks will result, because the racks are free-standing.
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. (b)
The temperature increase will not increase stresses on the new stainless steel racks because the design basis of the racks in-cludes the higher temperature.
(Af fidavit of Raymond F.
Sacramo, p. 2).
8.
Because a rise in temperature causes stainless steel to expand more than concrete and because restraints at the pool walls and floor corners restrict liner growth, the temperature increase resulting from the pool expansion will cause compressive forces and stresses to develop in the pool liner.
(Affidavit of Raymond F.
- Sacramo,
- p. 3).
9.
Because the temperature of the inside surface of the concrete pool walls and floor will rise to a maximum of 101 F while the temperature of the outside surface of the walls and floor will remain the same, a slight increase in the thickness thermal gradient will result, which could lead to increased stresses.
(Affidavit of Raymond F.
Sacramo, p. 3).
10.
The Affidavit of Raymond F. Sacramo addressing Christa-Maria Contention 8 and O'Neill Contention
. IIIE-2 shows that the liner and pool concrete both function even at the pool boiling temperature of 237 F; consequently, the slight increase in tem-perature to a maximum of 101 F represents a neg-ligible change in stresses both to the stainless steel linar and to the concrete pool walls and floor.
(Affidavit of Raymond F.
Sacramo, p. 3).
11.
Although the corrosion of a material reduces its cross-section area, leading to increased stresses, the corrosion rate of the materials in the stain-less steel pool liner and racks and the aluminum alloy racks in the spent fuel pool environment is too negligible to impair the structural integrity of these components.
(Affidavit of Raymond F.
Sacramo, p. 4).
C.
DISCUSSION The Affidavits of Daniel A.
Prelewicz, A. John Birkle and Raymond F.
Sacramo amply demonstrate that any increased corrosion or degradation of the materials in the spent fuel pool walls, pool liner, spent fuel racks or clad-ding of spent fuel elements resulting from the expansion of the pool capacity will be insignificant and will not impair the integrity of any of those components.
The basis for these
. conclusions is the calculation by Dr. Prelewicz of the increase in bulk coolant temperatures in the spent fuel pool resulting from radioactive decay of the fission pro-ducts contained in the additional spent fuel bundles that will be stored in the pool.
The amount of heat generated by a particular bundle depends on the length of time the bundle has been removed from the reactor core.
Consequently, the main heat source in the spent fuel pool is a fresh core discharge of fuel, either in the course of a normal refueling or in a full core offload.
Such discharges are always assumed for purposes of analysis, regardless of the capacity of the pool.
Expansion of pool capacity will merely permit storage of an increased number of old or decayed spent fuel bundles, which will generate only a small amount of ad-ditional heat.
Dr. Prelewicz 's calculations show that the maximum fuel pool temperature will be approximately 101 F for the expanded pool following a full core offload, compared with approximately 99 F for the present fuel pool capacity, an increase of 2 F.
The corresponding figures for the normal refueling sequence are 93 F for the expanded pool compared to 88 F at pre ent, an increase of 5 F.
These calculations are consistent with the figure of 95 F cited by John R.
Weeks in his affidavit submitted by the NRC Staff in support
. of its motion for summary disposition of O'Neill Contention IB-5.
On the basis of these small increases in tem-peratures, and the calculated corrosion rate of Type 304 stainless steel, the material of the pool liner and the new fuel racks (see material fact number 3, supra), Mr. Birkle concludes that the corrosion rate of the new racks and liner in the Big Rock fuel pool environment would probably not be detectable, and the temperature increase would have no measurable effect on this rate.
Therefore, the corrosion l
rate of the new racks will be insignificant, and the pool 3
liner corrosion rate will not be accelerated by the pool expansion.
Similarly, because the increase in temperature will be so small, stress-corrosion cracking of Type 304 stainless steel will not be accelerated by the expansion of the spent fuel pool.
(See material fact number 4, supra).
Although the corrosion rate of aluminum alloys, including the one used in the existing fuel racks, is sen-sitive to water temperature, Mr. Birkle concludes that the corrosion rate of the racks at the slightly increased pool temperature will be negligible.
Moreover, the 20-year period assumed in Mr. Birkle's affidavit is approximately twice as long as the remaining operating life of the Big Rock Point plant.
l
4 The Zircaloy cladding of the spent fuel elements has the lowest corrosion rate of the three metals studied and develops a strongly passivating oxide film which renders the corrosion rate negligible after ten years.
In the 101 F maximum temperature of the spent fuel pool, the corrosion rate of the Zircalloy cladding would be negligible.
Furthermore, on the basis of the temperature increases calculated by Dr. Prelewicz and Mr. Birkle's corrosion rate analyses, Mr. Sacramo concludes that no significant increase in stresses will occur in the fuel racks, the pool liner or the pool walls or floor.
For the 0
existing racks, the additional 5 F will cause a slight expansion in the aluminum, but because the racks are free-standing, this expansion will not create any internal structural stresses.
No accelerated stress will occur for the new racks because their design basis assumes the in-creased temperature of the expanded pool.
The stainless steel pool liner and the concrete walls of the pool will experience some stress from the in-creased pool temperature.
Stainless steel expands more than concrete from increased temperature and because the concrete walls and floor corners will resist this expansion, stresses will develop in the liner.
Furthermore, because the inside surface of the pool wall will experience increased tem-
l
-9 perature while the outside surface will not, an increased thermal gradient will result which could lead to increased stresses in the concrete.
Mr. Sacramo's affidavit addressing Christa-Maria Contention 8 and O'Neill Contention IIIE-2, however, has already shown that the liner and the pool concrete maintain their structural integrity even at the pool boiling temperature of 273 F.
The slight increase to 101 F therefore represents an insignificant change in liner and concrete stresses.
Finally, on the basis of the corrosion rates described by Mr. Birkle for the stainless steel fuel racks and pool liner and the aluminum fuel racks, Mr. Sacramo concludes that any increase in stress resulting from a reduction in the cross-sectional area of the material would be insignificant and would not impair the structural in-tegrity of those componenta.
No factual issue has been raised by Mr. O'Neill which controverts the facts established in the Affidavits of Dr. Prelewicz and Messrs. Birkle and Sacramo, as well as in the Affidavit of Mr. Weeks, and accordingly, the NRC Staff is entitled to summary disposition of O'Neill Contention IB-5 as a matter of law.