ML20031D717
| ML20031D717 | |
| Person / Time | |
|---|---|
| Site: | Allens Creek File:Houston Lighting and Power Company icon.png |
| Issue date: | 10/09/1981 |
| From: | Litton F NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | |
| Shared Package | |
| ML20031D662 | List: |
| References | |
| NUDOCS 8110140057 | |
| Download: ML20031D717 (5) | |
Text
,
10/0g/81 7
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of
)
HOUSTON LIGHTING & POWER COMPANY Docket No. 50-466
)
(Allens Creek Nuclear Generating
)
Station, Unit 1)
)
HRC STAFF TESTIMONY OF FELIX B. LITTON REGARDING IGSCC
[TEXPIRG CONTENT 1011 10J y.
Please state your name and position with the NRC.
A.
My name is Felix B. Litton.
I am a Senior Materials Engineer, Materit.ls Engineering Branch, Division of Engineering, Office of Nuclear Reguli; ion, U.S. Nuclear Regulatory Commission.
4 Have you prepared a statement of professional qualifications?
A.
Yes. A copy of qy professional qualifications has been attached to my earlier testimony in this proceeding.
Q.
Please state the scope of your responsibilities for the review of the Allens Creek application for a construction permit.
A.
I am responsible for the review and evaluation of those sections of the Applicant's Preliminary Safety Analysis Report for which the Material Application Section of the Materials Engineering Branch has primary review responsibility. This responsibility includes a review ofr the materials l
[
specified for fabricating Class 1, 2 and 3 components and the procedures which will be used to preserve the integrity of the component.
8110140057 811009 PDR ADOCK 050 g
y.
What.is the purpose of your testimony?
A.
The purpose of my testinony is to address TEXPIRG Contention 10 which states:
Applicant has not adequately demonstrated com-pliance with 10 C.F.R. Part 50, App. A, criterion 31, with regard to intergranular stress corrosion and cracking.
Excessive oxygen levels, superposed loads, and residual stresses may result in ultimate failure of piping, despite altered metal content for the ACNGS design, the NRC in-vestigation of stress corrosion, and cracking problems at similar BWR units was released in December 1975.
Q.
Has the Staff resolved the Unresolved Safety Issue A-42, " Pipe Cracks in Boiling Water Reactors?"
A.
Unresolved Safety Issue A-42 pertaining to intergranular stress corrosion cracking (IGSCC) has been resolved by NUREG-0531, Revision 1.
Q.
What is the background regarding this safety issue?
A.
Leaks and cracks in the heat-affected zones (HAZ) of welds that join stainless steel piping and associated components in boi. ling water reactors (BWR) have been observed since mid-1960.
Prior to September 1974, all the leaks and cracks were observed in Type 304 stainless steel piping with diameters of eight inches or less.
Technical evaluation of these occurrences attributed the cracks to intergranular stress corrosion due to the combination of high local stress, sensitation of the material, and a high oxygen content in the water.
During the last quarter of 1974, incidence of IGSCG were reported in the recirculation bypass lines (4-in. diameter) and the core spray liner (10-in. diameter). As a result, a Study Group was formed to investigate l
the cause. The study group published NUREG-75/067 " Technical Report, l
Investigation and Evaluation of Cracking in Austenitic Stainless Steel Piping of Boiling Water Reactor Plants," in October 1975. The report contains recommendations for reducing the incidences of IGSCC in stain-less steel piping.
Intergranular stress corrosion cracking continued to be observed in the recirculation bypass and core spray piping.
In the period between 1975 and 1978, incidents of IGSCC were observed in the recirculation riser p1 ping (12-in. diameter) and recirculation piping in foreign BWRs
( 20-in, diameter). A new Study Group was formed to re-examine the cor.clusions and recommendation of the previous Study Group and to assess the significance of the safe-end cracking found at Duane Arnold.
During this same time period, a Study Group was formed by the General Electric Company to conduct an independent evaluation. The GE Study Group submitted their recommendations to the Staff in f4ED0-21000,
" Investigation of Cause of Cracking in Austenitic Stainless Steel Pipe."
The flRC and GE Pipe Crack Study Groups concluded that three conditions must be present for intergranular stress corrosion cracking to occur.
The conditions are:
(1) tensile-type stress, including residual stress from fabrication, (2) corrodent, an environment in which an electrochemical reaction can occur, and (3) susceptible material. The degree to which one of these conditions must be present for intergranular stress corrosion cracking to occur is variable and depends on the degree to which the other conditions are present.
An implementation document was issued following the Staff's review of the fiRL and GE Pipe Crack Study Group's recommendation. This document, fiUREG-0313, Revision 1, " Technical Report on Material Selection and Processing Guidelines for BWR Coolant Pressure Boundary Piping," sets l
forth nethods acceptable to the NRC Staff to redure the incidents of intergranular stress corrosion cracking in ASME Code Class 1, 2 and 3 boiling water reactor pressure boundary piping and safe ends.
NUREG-0313, Revision a, constitutai the Staff's resolution of the Unresolved Safety Issue A-42, " Pipe Cracks in Boiling Water Reactors."
4 What is the purpose of NUREG-0313, Revision 17 A.
The purpose of NUREG-0313, Revision 1 is to set forth criteria acceptable to the Staff to reduce the susceptibility of BWR piping systems to IGSCC and to provide an increased level of integrity to the BWR piping systems. These criteria have been set forth even though the Staff concluded in NUREG-0531, " Investigation and Evaluation of Stress-Corrosion Cracking in Piping of Light Water Reactor Plants" that IGSCC in the BWR piping systems, although undesirable, will not present a hazard to the health and safety of the public.
Q.
Is the Applicant in compliance with the recommendation of NUREG-0313, Revision 17 A.
The Applicant is in compliance with the recommendations of NUREG-0313, Revision 1.
NUREG-0313, Revision 1, recommends the use of materials in l
the BWR piping systems not susceptible to intergranular stress corrosion cracking, and, in the event susceptible materials may be used, an augmented inservice inspection program to detect the growth of cracks before leakage occurs.
Q.
What steps have been taken by the Applicant at the Allens Creek facility to minimize the occurrence of IGSCC?
A.
The Applicant is using material not susceptible to IGSCC it, the Feedwater, Main Steam, Residual Heat Removal and Essenti61 Services Cooling l
Water Systems, and, in coupliance to the recomnendation of fiUREG-0313 Revision 1 he has agreed to conduct an augmented inservice inspection on parts of the piping systems which may be fabricated from susceptible materials.
In addition, the recirculation bypass and the control red drive hydraulic lines, where the bulk of IGSCC has occurred, have been eliminated from the Allens Creek fluclear Generating Station design.
The program undertaken by the Applicant is based upon an accurate and full understanding of the cause and prevention of intergranular stress corrosion cracking in BWR stainless steel piping systems. We conclude that the Applicant's program is acceptable and complies with the Staff's recommendations.
Q.
What other f4RC recommendations must be adhered to by the Applicant to demonstrate acceptable resistance to IGSCC?
A.
The Applicant has agreed to comply with the recormendations of Regulatory Guides 1.44.
Section C.3 of Regulatory Guide 1.44, " Control of the Use of Sensitized Stainless Steel," provides that non-sensitization of stainless steel materials should be verified by using '.TM A-262-70,
" Recommended Practice for Detecting Susceptibility to Intergranular Attack in Stainless Steel." The Applicant's compliance with Section C.4 of Regulatory Guide 1.54, " Quality Assurance Requirements for Protective Coatings Applied to Water-Cooled fluclear Power Plants" which states that coating and cleaning materials used with stainless steel should not be compounded to contain chemicals that could contribute to IGSCC, is ad-dressed in separate testimony.
. - _.