ML20150C532
| ML20150C532 | |
| Person / Time | |
|---|---|
| Site: | Black Fox |
| Issue date: | 11/03/1978 |
| From: | Gallo J ISHAM, LINCOLN & BEALE |
| To: | Purdom P, Shon F, Wolfe S Atomic Safety and Licensing Board Panel |
| References | |
| NUDOCS 7811240076 | |
| Download: ML20150C532 (12) | |
Text
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WC PUI3LIC DOCUMENT ROOM ISHAM, LINCOLN & BEALE COUNSELORS AT LAW 1050 t ?!? ST R E ET, N. W.
$ EVE NTH FLOOR WAS H8 NG TON, D. C. 2OO 3 6 TELEPHONE 202 833 9730 k
CHICAGO OFr#CE ONE renST N ATIONA L PLATA rot <TV-5 ECONO FLOOR C HICAGO,lLLIN065 60803
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November 3, 1978
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l Sheldon J. Wolfe, Esquire MD 4
Atomic Safety and Licensing Board Panel U.S. Nuclear Regulatory Commission d [f y
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Washington, D.C.
20555 qv Mr. Frederick J.
Shon, Member V
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Atomic Safety and Licensing Board Panel U.S.
Nuclear Regulatory Commission M
j Washington, D.C.
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Dr. Paul W.
Purdom Director, Environmental Studies Group Drexel University 32nd and Chestnut Streets i
I Philadelphia, Pennsylvania 19104 Gentlemen:
I am enclosing copies of Applicants' testimony concerning Contention 19.
Mr. Stippich's testimony is also being served on all parties by copy of this letter.
The original filing date for this testimony was Friday, October 27, 1978.
- However,
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a motion.was filed on October 26 requesting that for good cause j
shown the time be extended to November 3.
Neither counsel for j
the NRC Staff nor the Intervenors opposed this motion.
The
~
Licensing Board has not yet ruled on the motion.
Applicants renew its request that the motion be granted and that the enclosed testimony be filed on the above-captioned docket.
i l
Sincerely, j
N11M C)Q7(,
Jose h Gallo One of the Attorneys for the Applicants i
JG:kar Enclosure cy:
Messenger delivery te Counsel for the NRC Staff and Messrs Wolfe and Shon.
Federal Express delivery to Counsel for the Intervenors.
Mail copy to all others on service list.
TESTIMONY OF ROBERT E.
STIPPICH CONCERNING CONTENTION 19 (TURBINE MISSILES) i My name is Robert E.
Stippich.
I reside at 4322 Mercier Street, Kansas City, Missouri.
I am a employed in the Systems Department at Black & Veatch Consulting Engineers in Kansas City, Missouri, an Architect / Engineering firm retained by Public Service Company of Oklahoma.
I prepared the turbine missile analysis for the Black Fox Station.
A statement of my background and qualifications is attached as Attachment II.
My testimony addressec Contention 19 which provides:
"Intervenors contend that the Applicant has not adequately demonstrated that Black Fox, 1 and 2 will comply with 10 CFR, Part 50, Appendix A, Criteria 4, in that the potential dynamic effects on the containment associated with internally generated turbine missiles have not been adequately considered."
My testimony will show that the containments for the Black Fox Station are appropriately protected against the effects of missiles that might result from failure of the turbine in a main turbine-generator set.
The turbines are located outside of the containment, consequently turbine missiles are external missiles relative to the containment.
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I.
Background
Turbine failures with missile ejection have been experi-enced with conventional turbine-generator units in the past.
A similar failure of a nuclear turbine might result in the ejection of a misaile with a potential for damaging an essen-tial system.
Consequently, the effects of turbine missiles on plant safety need to be assessed.
Historically, turbine failures have occurred in one of two modes; design overspeed failure below about 110 per cent of operating speed resulting from brittle fracture of a i
low premsure turbine disk at a low stress level, or destructive i
overspeed failure in the range of 170 to 180 per cent of operating speed resultiny from failure of the overspeed pro-tection system with a consequent ductile failure of a low pressure turbine disk at a stress level above the yield point.
A turbine missile is a segment of a low pressure turbine disk which, after punching through the turbine casing, exits above the horizontal plane in a direction near the original plane of the disk.
The direction is constrained to a maximum angle from the disk of 5 degrees for interior disks and 25 degrees outward for end disks.
A missile can be categorized as either a high trajectory missile or a low trajectory missile depending on its initial direction as it exits from the turbine casing.
A high trajectory missile, a so-called " lob-shot" missile, is one which is ejected nearly vertically upward and falls almost straight downward landing in the plant area.
It has the potential for landing on the roof of a plant structure.
. A low-trajectory missile, a so-called " direct" missile, is one which is ejected at a low elevation angle.
It han a potential for striking the wall of a nearby plant structure.
The probability of a strike on the containment of Unit 1 by a low-trajectory missile from its own turbine-generator unit has been reduced to virtually zero by using a peninsular arrangement as shown in Attachment I.
With this arrangement the containment for Unit 1 is entirely outside of the 25 degree low-trajectory missile strike zone of its own turbine-generator unit.
Only a low-trajectory missile from the j
adjacent Unit 2 needs to be considered in assessing the effects on plant safety.
Essential systems, such as the containment, are housed in protective structures which serve as barriers against exter-nal missiles including turbine missiles.
The containment is housed in the Shield Building which is a substantial reinforced 4
concref, structure with walls three feet thick and a roof two feet thick.
Additional protection against low-trajectory i
missiles from the adjacent unit is afforded by substantial i
reinforced concrete shield walls along the sides of the Turbine Building.
These walls will be at least three feet thick.
Although their primary function is radiological shielding, they are also effective barriers against turbine missiles.
For a low-trajectory missile to cause unacceptable damage to the containment, it must perforate the three feet thick concrete shield wall of the Turbine Building, traverse 550 feet to 1
the Shield Building, perforate the three feet thick rein-forced concrete structure, traverse five feet to the contain-ment vessel and finally perforate the one and one-half inch thick carbon steel vessel.
For a high-trajectory missile to cause unacceptable damage to the containment, the missile must exit the turbine casing at a suitable speed and direction to reach and perforate the two feet thick roof of the Shield Building and the one and one-half inch thick carbon steel vessel.
Achievement of either of these events, requires a substantial missile with suitable properties of speed, weight, and frontal area.
II.
Basis For Analysis The containment is considered to be adequately protected 1
if the risk of unacceptable damage to the containment from turbine missiles does not exceed 10-7 per year.
This design objective has been established by the NRC Staff in Regulatory Guide 1.115.
The risk presented by a postulated turbine failure is determined by evaluating and combining three conditional probabilities; the probability of a turbine failure with l
missile ejection, P1; the probability of a damaging strike on the Shield Building, P2; and the probability of unaccept-If P1xP2xP3 is 10-7 or able damage to containment, P3 less per year, the risk is considered to be acceptable.
.-<r The probability of turbine failure with missile ejection, P1, used in the assessment of turbine missile risk to the con-1 tainment is 10-4 per year.
This failure rate is the same as that reported by Spencer H. Bush, Senior Staff Consultant at Battelle Pacific Northwest Laboratories, in his article
" Probability of Damage to Nuclear Components Due to Turbine Failure," Nuclear Safety, Volume 14, No.
3, May-June 1973, i
Dr. Bush's failure rate is based on a review of historical turbine failure data for conventional steam turbines covering 70,000 turbine-years of operation.
The vendor of the turbine-generator units for the Black Fox Station cxpects the failure rate for nuclear torbines to be substantially lower than the historical failure rate because most of the design, manufacturing, and operating practices responsible for historical failures of conventional turbines do not apply to nuclear turbines.
Consequently, a failure rate of 10-4 is considered to be ultra-conservative.
Turbine failure is discussed in PSAR Gection 3.5.2.1.1.
The probability of a damaging strike, P2, by a high-trajectory missile landing on the roof of the Shield Building is a combination of the probability of hitting the roof and the probability of penetrating the roof and striking the con-tainment with sufficient force to cause unacceptable damage to the containment vessel.
The probability of hitting the roof is the product of the susceptible plan area of the Shield Building roof and the unit area probability of the missile i
1 landing in the immediate vicinity of the plant.
The probability of penetrating the roof and striking the containment depends on the missile properties and is conservatively based on impact by the largest feasible missile, a 120 degree segment of a last stage disk, evaluated using the modified National Defense Research Committee (NDRJ) formula.
This formula was validated experimentally for tornado missiles by Sandia l
Laboratories for the Electric Power Research Institute and is the same formula referenced in Regulatory Guide 1.115.
The maximum high trajectory missile velocity to be reasonably expected is approximately 500 feet per second.
However, it would be unconservative to postulate this speed for purposes c f the analysis.
This is true because the probability of the missile striking the susceptible area of j
the roof of the Shield Building becomes less as the speed of the missile increases because the unit area strike probability decreases with the speed of the missile.
Thus for purposes of optimizing potentially competing parameters, the missile with the slowest speed but still capable of causing unaccept-able damage to the containment must be identified.
This has been done in the analysis to achieve a conservative probability of a damaging strike, P2, by a high trajectory missile.
On this basis, P2 for the Shield Building is 10-3 or less.
Given a turbine failure with ejection of a missile and a damaging strike on a Shield Building, the probability of unacceptable damage, P3, to the containment inside is con-servatively assumed to be one, a certainty.
' Accordingly, the overall risk, P1xP2xP3, to the con-tainment from high-trajectory turbine missiles from postulated turbine failures at either design overspeed or destructive overspeed is 10-7 per year or less.
The probability of a damaging strike, P2, on a Shield Building wall by a low-trajectory turbine missile from the adjacent unit is a combination of the probability of striking the Shield Building wall and the probability of penetrating l
the wall (taking into account the intervening barrier, i.e.,
the three feet thick reinforced concrete shield walls of the Turbine Building), and striking the containment with suf-ficient force to cause unacceptable damage to the contain-ment vessel.
The probability of a strike depends on the 1
solid angle subtended by the wall and the total directional solid angle at the missile source.
The probability of J
penetration is based on the exit speed of the largest feasible missile; again a 120 degree segment of a last stage disk evaluated by the modified NDRC formula.
The probability of a damaging strike, P by a low-trajectory missile on the 2,
containment is 10-3 or less.
This is within the criteria of Regulatory Guide 1.115.
Accordingly, the overall risk, P1xP2xP3, to the containment from a low trajectory missile from a postulated turbine failure at either design overspeed or destructive overspeed is less than 10-7 per year.
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III.
Conclusion Conservatively based analyses of high-trajectory and low-trajectory missiles from both design overspeed and destruc-tive overspeed failures yield results which meet conservative acceptance criteria.
It is concluded that compliance with 10 CFR, Part 50, Appendix A, Criterion 4 respecting potential dynamic effects of turbine missiles on the containment has been demonstrated.
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ATTACHMENT II
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I SYSTEMS ENGINEER:
Robert E.
Stippich EDUCATION:
BS, Civil Engineering, 1949 Washington University EXPERIENCE:
I joined Black & Veatch, Consulting Engineers in 1953, and I am presently a Consultant in the Systems Engineering Department.
I was Section Leader of the Systems Engineering Department Speciality Services Section with responsibilities for licensing and design tasks in the areas of seismic and pipe rupture design, turbine missile analysis, and coordination review of all regulations, regulatory guides, and industry codes and standards.
I was formerly a systems engineer with responsibility
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for conducting systems analyses and for performing engineering design of the civil and structural engineering features of large nuclear and fossil fuel electric power plants.
i I have participated in several nuclear power plant design and feasibility study projects.
On these projects, I was responsible for structural layouts, design, functional analyses and cost estimates for containment structures including pressure suppression containments for boiling water reactors and dry containments for pressurized water reactors.
In addition, I was responsible for the evaluation of the geologic, seismologic, hydrologic, and meteorologic site factors related to the contain-ment design.
I also participated in studies of the technical and economic feasibility of the Molten Salt Reactor, developing i
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plant arrangements and conceptual designs for containment and structures.
I supervised preparation of detailed design, plans and specifications for structures, foundations and other civil engineering features of large steam-electric power plants.
In all, I have participated in the design of more than 50 power plants.
I am presently serving on the Task Committee on Turbine Foundation of the ASCE Power Division.
i Prior to joining Black & Veatch, I was employed by Boeing 1
Airplane Company, Seattle, Washington where I served as a senior facilities engineer working in design and in equipment vibration control, structural dynamics and noise control.
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served as an officer in the United States Navy.
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