ML20009E353
| ML20009E353 | |
| Person / Time | |
|---|---|
| Site: | Allens Creek File:Houston Lighting and Power Company icon.png |
| Issue date: | 07/20/1981 |
| From: | Mercurio W EBASCO SERVICES, INC., HOUSTON LIGHTING & POWER CO. |
| To: | |
| References | |
| NUDOCS 8107280072 | |
| Download: ML20009E353 (7) | |
Text
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July 20, 1981
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1 UNITED STATES OF AMERICA 1
11 NUCLEAR REGULATORY COMMISSION k
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BEFORE THE ATOMIC SAFETY AND LICENSING BOARD g 0:
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HOUSTON LIGHTING & POWER COMPANY
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6 Station, Unit No. 1)
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DIRECT TESTIMONY OF WILLIAM F. MERCURIO;C)I BEIbiLF hm OF HOUSTON LIGHTING & POWER COMPANY ON DOHERTY y
CONTENTION 29 BLOCKAGE OF INTAKE CANAI/ 'E G 9
10 Q.
Mr. Mercurio, please state your name and 11 business address and describe your educational and 12 professional experience.
13
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My name is William F. Mercurio, and my business 3,
14 address is Ebasco Services, Inc., 2 World Trade Center, 15 New York, N.Y.
I have previously discussed my position 16 and background in connection with my testimony on Bishop 17 Contentions 4, 5,
7, 9 and 10.
18 Q.
What is the purpose of your testimony?
19 A.
The purpose of my testimony is to address 20 Doherty Contention 29 which alleges that, "there is insufficient assurance that postulated 21 failures would [not] lead to unacceptable blockage of the submerged intake canal.
These 22 insufficiencies present a risk of meltdown of core if residual heat removal system water is by 2#
insufficient after a core damaging accident."
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Q.
What is your understanding of the basis for this contention?
A.
It is my understanding that this contention is based on Supplement 2 to the Safety Evaluation Report in which the NRC Staff states that failure of manmade 5
structures will not impair the minimum acceptable functional 6
capability of the ultimate heat sink (UHS) provided that 7
appropriate design changes are implemented.
I 8
Q.
What is the p:Irpose of the Ultimate Heat Sink?
9 A.
The UHS provides a source of cooling water for 10 the Essential Services Cooling Water System for safe 11 plant shutdown in the event water would be absent from 12 the ACNGS cooling lake.
13 Q.
Describe the physical characteristics and 14 operation of the Ultimate Heat Sink.
15 A.
The UHS consists of a 50 acre submerged evapora-16 tive pond formed by excavating the floor of the cooling 17 lake to a depth of approximately 8 ft.
A canal connects l
I 18 the evaporative pond with the UHS intake structure.
The 19 pond will have a discharge structure and an interior diversion dike.
20 The normal source of cooling water for ACNGS is the 21 4,800 acre cooling lake and water will be supplied from 22 this heat sink whenever it is available.
In the event 23 24 t _.
1 of a total loss of cooling water in the lake, the submerged 2
pond will supply the essential services cooling wate,r 3
system and is more than adequate to permit emergency 4
shutdown and cooldown of the plant for 4 months.
5 Q.
Briefly describe the submerged intake canal.
6 A.
The submerged intake canal is a safety related 7
underwater reinforced concrete canal approximately 35 8
feet wide and 100 feet long with reinforced concrete 9
retaining walls of variable height and approximately 2 10 feet thick.
This canal serves the purpose of channeling 11 water from the UHS to the UHS intake structure.
12 Q.
What structure, if postulated to fail, would 13 be the most likely to cause unacceptable blockage of the 14 intake canal?
A.
The UHS causeway, because a postulated failure 15 w uld m st likely occur in recompacted earthen material.
16 Q.
Describe the UHS causeway.
17 A.
Access to the UHS intake structure is via a mana.ade "then causeway extending from the main plant area and abutting tite UHS intake structure.
The causeway is designed to be stable following a safe shutdown 21 earthquake or any other severe natural phenomena.
The 22 causeway will be at an approximate elevation of 145 feet 23 above sea level which is 27 fe.et above the cooling lake 24 normal maximum elevation.
1 Q.
What types of studies have been performed to 2
serify the design of the UHS causeway?
3 A.
Studies were performed by taking a representa-4 tive cross-section of the various soil strata and analyzing 5
them to assure the stability of the causeway slope for 6
different loading conditions.
7 Two general methods of analysis as described in 8
Section 2.5 Appendix M of the ACNGS PSAR were used to 9
investigate the stability of the UHS causeway slope under var'ous conditions.
They are:
10 1)
The simplified Bishop slip circle method.
11 2)
The U.S. Army Corps of Engineers sliding 2
w dg m thod.
3 Q.
Briefly describe the results of these studies.
A.
Utilizing the most conservative approach, in terms of design parameters, loading conditions and 16 assumptions, the study results yielded a minimum factor 17 l
of safety well within the acceptable limits established 18 by the Army Corps of Engineers.
The results of these 19 studies are presented in the PSAR Section 2.5 Appendix M.
20 Q.
Why is a concrete retaining wing wall structure 1
21 to be provided at the entrance to the UHS intake canal?
22 A.
In accordance with the NRC Regulatory Guide 1
23 1.27, an analysis was performed which postulated the 24 l
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1 failure of the manmade causeway.
A cross section taken 2
at the lake front area was inves tigated for the pote,ntial 3
blockage of the waterway, should the causeway be postulated 4
to fail in this area.
The movement of the postulated 5
failure plane was examined and found to yield a conservative 9
6 soil movement of less than 4 inches.
This soil movement 7
would produce a very minor bulging type of deformation 8
that would be experienced in the causeway along the lake 9
front area.
10 As an additional conservatism and in order to 11 provide a positive stoppage of soil movement, a concrete 12 retaining wing wall structure will be provided at the 13 causeway lake front area to assure a continuous passage 14 f cooling water into the intake canal.
Q.
Describe the retaining wing wall structure and 15 its function.
6 A.
The retaining wing wall structure consists of a pair of seismic Category I reinforced concrete walls Each wing is angled outward at approximately 45* away 19 from the submerged intake canal to which it is attached.
20 These wing walls direct the postulated flow of soil 21 material away from the intake canal.
22 Q.
Has the addition of a concrete retaining wing 23 wall structure satisfied the NRC Staff's design change 24 concern statad in the SER, Supplement 2?
1 A.
Yes.
2 Q.
In addition to the analysis of the UHS causeway, 3
has the Applicant analyzed the stability of the slopes 4
of the UHS?
5 A.
Yes.
Similar to the UHS causeway, we have 6
analyzed the slopes of the heat sink.
The results of 7
these analysis are presented in the PSAR Section 2.5 8
Appendix M and indicate that the slopes are stable.
9 Q.
Has this study also considered the potential 10 effects of sedimentation in the UHS submerged intake 11 canal?
A.
Yes.
The slopes of the canal have been flattened 12 to allow. the sediment to assume its natural angle of 13 repose so that it would not flow into the UHS intake 4
structure.
A discussion of this feature is presented in Section 9.2.5.2 of the PSAR.
16 Q.
Has any other design measure been incorporated 17 into the UHS design to further limit the effects of 18 sedimentation?
19 A.
Yes.
A one foot high sill will'be placed at 20 the front of the UHS intake structure to further assure 21 that sediment will not flow into the structure.
22 Q.
What are your conclusions concerning this 23 contention?
24.-
1 A.
Slope stability analyses have been performed 2
and demonstrate that more than adequate safety factors 3
ensure that UHS causeway slopes and UHS side slopes will 4
not fail and cause blockage of the 'THS intake canal.
5 The additional conservatism of employing a concrete 6
retaining wing wall on the intake canal further assures 7
that even in the highly unlikely event that the UHS causeway slope was to fail, positive stoppage of soil 8
movement Would be assured and the UHS intake canal would g
t be blocked.
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