ML20008F994
| ML20008F994 | |
| Person / Time | |
|---|---|
| Site: | Allens Creek File:Houston Lighting and Power Company icon.png |
| Issue date: | 05/11/1981 |
| From: | Litton F Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20008F949 | List: |
| References | |
| NUDOCS 8105120472 | |
| Download: ML20008F994 (5) | |
Text
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s 05/11/81 UNITED STATES OF AMERICA NOCLEAR REGULATORY COMMISSI0t; BEFORE THE AT0f1IC SAFETY AND LICENSING BOARD In the 11atter of
)
H00ST04 LIGHTI43 AND POWER COMPAllY Docket No. 50-466 (Allens Creek Huclear Generating Station, Unit 1)
)
NRC STAFF TESTIMONY OF FELIX B.
LITTON RELATIVE TO JET Put1P HOLD-DOWN BEAMS
[Doherty Contention 50]
Q.
Please state your name and position with the NRC.
A.
My name is Felix B. Litton.
I am a Senior flaterials. Engineer with the Materials Engineering Branch of the Division of Enginearing. A l
copy of my statement of professional qualifications is attached.
Q.
tihat is the ourpose of this testimony?
i A.
The purpose of this testimony is to respond to Doherty Contention 50 which basically alleges that jet pump hold-down beans will crack during operation resulting in coolant circulation degradation. A complete statement of the contention is set forth belos:
Applicants jet pumps in the coolant circulation systen of the proposed ACNGS will be subject to disassembly, and/or hazardous displacement resulting in coolant circulation degradation during operation leading to reduction of the nargin of safety during normal operation or design basis accidents (DBA), due-to cracking in reactor internal parts for holding the jet pumps in place and the jet pupp itself.
4 810512e(h
O i Q.
Does the Staff share !!r. Doherty's concern about cracking in jet pump hold-down beaus?
A.
Yes.
Q.
Would you briefly sumarize the source of the Staff's concern with this pro' lem?
o A.
On February 2,1980 a jet pump failed at Dresden Unit 3 while.
operating at about 67 percent of power in a coast down mode to refueling shutdown.
Pump failure was attributed to the failure of the jet pump Inconel X-750 nold-down beam.
In compliance with IE Bulletin ilo. 80-07, "BWR Jet Pump Assembly Failure," subsequent examination at other BWR facilities showed cracked hold-down beams in nine of twenty-six plants exanined.
Q.
Has this problem been evident in BWR designs other than the BWR-3?
A.
i40.
The cracks in the hold-down beams are limited to the BWR-3 reactor design.
Q.
What steps did GE take in response to the identification of the hold-down beam cracking problen in the nine BWRs mentioned above?
i A.
The General Electric Company conducted a metallurgical investigation to determine the cause and steps for prevention of crack initiation in Inconel X-750 jet pump hold-down beams. The result of the investigation showed that intergranular stress corrosion under sustained l
loading was the cause of failure.
Subsequent tests under sinulated l
operating conditions denonstrated that heat treatment of the Inconel l
X-750 to change the distribution of ganma phase in the alloy resulted in
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a substantial increase in the length of tine to crack initiation in test specimens.
Q.
As a result of its investigation, did GE nake any reconoendations for alleviation of this problen?
A.
Yes. The General Electric Company reconmended that the jet pump hold-down beans be he'at treated at'a higher solution temperature (2000*F.
for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> instead of 1625'F. for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) and that preload used for bean installation be reduced froa 30 kips to 25 kips. A GE statistical study indicates that these recommendations will essentially double the time for crack initiation in the jet pump hold-down beams.
Q.
When you say that the GE study indicates that time for crack initiation will be essentially doubled, what general time periods are you talking about?
A.
GE concluded that the tine for crack initiation would be i
extended by adoption of both of its recomnendations from the range of 9-16 years to over 40 years.
Q.
Does the Staff concur in GE's analyses and reconaendations with regard to alleviation of the hold-down beau cracking phenomenon?
I A.
Yes.
In fact the GE recommendations will be imposed as requirements in the Allens Creek fabrication and tecnnical specifications.
Q.
How have the design changes from the BWR-3 to the BWR-6 affected the potential for development of hold-down beam cracking in the Allens Creek t'acility?
A.
The potential for such cracking is less in the Allens Creek BWR-6 design than in the BWR-3 design. This is because the stresses in
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the BWR-6 jet pump beaa are loser than in the BWR-3 design as a result of the utilization of beans with heavier cross sections.
Q. What is your conclusion with regard to the potential for jet pump hold-down beaa cracking at the Allens Creek facility?
A.
Such cracking should not occur during the operating life of the facility because of (1) the lower stresses inherent in the 5.JR-6 design and (2) adoption of the GE recommendations with regard to heat trea'uaent and preload as fabrication and tech spec requirements.
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PROFESSIONAL QUALIFICATIONS FELIX B. LITTON I am a Senior Materials Engineer in the Materials Engineering Branch of the Office of Nuclear Reactor Regulation, Nuclear Regulatory Commission.
I am assigned to the Inservice Inspection and Conponent Integrity Sections and my duties involve the review and evaluation of materials and processes tsed in the construction and operation of components in the nuclear power industry.
My education consists of a B. S. (1936) and M. S. (1937) degree in Physical Chenistry from Virginia Polytechnic Institute Blacksburg, Va.
I have completed additional study in Material Science at the University of New Mexico and have taken special courses in Fracture "echanics and other job oriented courses at Union College and Georce Washinoton University.
Prior to joining the Nuclear Regulatory Commission, my exoerience consists of metallurgical research related to the preparation, fab'rication and alloy formation of new structural materials for nuclear, advanced aircraft and high temperature application.
I have published in technical journals on the environmental behavior, thermodynamic stability and mechanical oroperties of uranium, plutonium, vanadium, zirconium, tetanium, hafrium and silicon and their alloys. Although my orimary experience in ferrous metallurgy has related to the cause of material failure in service, I have managed metallurgic.
research on welding and welding processes.
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