ML19210A646
| ML19210A646 | |
| Person / Time | |
|---|---|
| Site: | Crane, North Anna  |
| Issue date: | 09/14/1977 |
| From: | Reid R Office of Nuclear Reactor Regulation |
| To: | Herbein J METROPOLITAN EDISON CO. |
| References | |
| NUDOCS 7910300676 | |
| Download: ML19210A646 (5) | |
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DISTRIBUTION:
September 14, 1977 Docket File NRC PDR Gray File gt%
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L PDR Docket No.: 50-289 ORB #4 Rdg RReid RIngram Petropolitan Edison Coapany GZwetzig ATTN: Mr. J. G. Herbein RSnaider Vice President TCarter P. O. Box 542 Attorney, OELD Reaoing, Pennsylvania 19603 OI&E (3)
DEisenhut Gentlemen:
TBAbernathy JRBuchanan RE: FRACTURE TOUGHNESS AND POTENTIAL FOR LAMELLAR TEARING OF STEAlt GENERATCR A110 REACTCR C00LAfff PUHP SUPPORT HATERIALS During the ccurse of the licensing action for North Anna Power Station Unit Nos. I and 2, a gnber of questions were raised a*, to the potential for lamellar tearing l! and low fracture toughness of the stea-t generator and reactor coolant pur.o support caterials for that plant. Two different steel specifications ( ASTH A36-70a and ASTM AS72-70a) covered most of the material used for these supports. Toughness testc, not originally speci-fied and not in the relevant ASTM specifications, were made on those ~
heats for which excess material was available. The toughness of the A35 steel was fcund to be adequate, but the toughness of the A572 steel was relatively poor at an operating temperature of 60 F.
In this case, the arolicant has agreed to raise the temperature of the ASTM A572 bemes in the steam generator supports to a minimun temperature of 225 F prior to reactor coolant systen pressurization to levels above 1000 psig. Auxil-iary electrical heat will be employed to supplement the heat derived froa the reactor coolant loop as necessary to obtain the required operating temperature of the structures.
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.Il Lamellar tecring is a cracking phenomenon which occurs beneath welcs and is principally found in rolled steel plate fabrications. The tearing always lies within the parent plate, often outside the transforned (visible) heat-affected zone (HAZ) and is generally parallel to the weld fusion boundary. Lamellar tearing occurs at certain critical joints usually within large welded structures involving a high degree of stiffness and restraint. Restraint may be defined as a restriction of the povecient of the various joint components that would nomally occur as a result of expansion and contraction of weld metal and adjacent regions during welding.
("Lamellar Tearing in Welded Steel Fabrication", The Welding ff Institute).
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Metropolitan Edison Company Since similar materials and designs have been used on other nuclear plants, the concerns raised on the supports for the North Annt, plant may De applicaDie for other operating PWR plants.
It is therefo/e necessary to reassess the fracture toughness and potential for lamellar tearing of the steam generator and reactor coolant purap supporc materials for all operating PWP. plants.
We will require certain infomation to make the necessary resssessment of the steam generator and reactor coolant pump support materials for your olant; therefore, please provide the following information within sixty (60) days after receipt of this letter:
1.
Provide engineering drawings of the steam generator and reactor coolant pump supports sufficient to show the geometry of all principal elements. Provide a listing of materials of construction.
2.
Specify the detailed design loads used in the analysis and design of the supports. For each lording condition (nomal, upset, emergency and faulted), provide the calculated maximum stress in each principal ele-ment of the support system and the corresponding allowable stresses.
3.
Describe how all heavy section intersecting member wel&ents were
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designed to minimize restraint and lamellar tearing. Specify the actual section thicknesses in the structure and provide details of typical joint designs. State the maxirium design stress used for the
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through-thickness direction of plates and elements of rolled shapes.
4.
Specify the minimum operating temperature for the supports and
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describe the extent to which material temperatures have oeen measured at various points on the supports during the operation of the plant.
5.
Specify all the materials used in the supports and the extent to which mill certificate data are available. Descrioe any suoplemental requirements such as melting practice, toughness tasts and tnrougt-thickness tests specified. Provide the results of all tests that may better define the properties of the materials used.
6.
Describe the welding procedures and any soecial welding process requirements that were specified to mininize residual stress, weld and heat affected zone cracking and lamellar tearing of the base me tal.
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Petropolitan Edison Company 7.
Describe all inspections and non-destructive tests that were perfome.i on the supports during their fabrication and installation, as well as any additional inspections that were perfomeo during the life of tne f acil i ty.
In addition to the infomation requested above, please provide your own evaluation of the fracture toughness of the stean generator and reactor coolant pump support materials for your plant. Please infom us within thirty (30) days after receipt of this letter of your schedule for pro-vicing us with your evaluation. This generic request was approved by GAO, L 180225 (R0072), clearance expires July 31, 1960. Approval was given under a blanket clearance specifically for identified generic problens.
Since rely,
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Robert W. Reid, Chief Operating Reactors Branch #4 Division of Operating Reactors s
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Metropolitan Edison Company cc:
G. F. Trowbridge, Esquire Shaw, Pittman, Potts & Trowbridge 1800 M Street, N. W.
Washington, D. C.
20036 GPU Service Corporation Richard W. Heward, Project Manager Thomas M. Crimmins, Jr., Safety and Licensing Manager 260 Cherry Hill Road Parsippany, New Jersey 07054 Pennsylvania Electric Company Mr. R. W. Conrad Vice President, Generation 1001 Broad Street Johnstown, Pennsylvania 15907 Mr. Weldon B. Arehart, Chairman Board of Supervisors of Londonderry Township RFD#1, Geyers Church Road Middletown, Pennsylvania 17057 Miss Mary V. Southard, Chai inan Citizens for a Safe Environment P. O. Box 405 Harrisburg, Pennsylvania 17108 Government Publications Section State Library of Pennsylvania Box 1601 (Education Building)
Harrisburg, Pennsylvania 17126 1492 30l
Metropolitan Edison Company cc:
G. F. Trowbridge, Esquire Shaw, Pittman, Potts & Trowbridge 1800 M Street, N. W.
Washington, D. C.
20036 GPU Service Corporation Richard W. Heward, Project Manager Thomas M. Crimmins, Jr., Safety and Licensing Manager 260 Cherry Hill Road Parsippany, New Jersey 07054 Pennsylvania Electric Company Mr. R. W. Conrad Vice President, Generation 1001 Broad Street Johnstown, Pennsylvania 15907 Mr. Weldon B. Arehart, Chairman Board of Supervisors of Londonderry Township RFDel, Geyers Church Road Middletown, Pennsylvania 17057 Miss Mary V. Southard, Chairman Citizens for a Safe Environmcnt P. O. Box 405 Harrisburg, Pennsylvania 17108 Government Publications Section State Library of Pennsylvania Box 1601 (Education Building)
Harrisburg, Pennsylvania 17126 2
1492 305 S