ML19326C324
| ML19326C324 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 09/14/1977 |
| From: | Desiree Davis Office of Nuclear Reactor Regulation |
| To: | Cavanaugh W ARKANSAS POWER & LIGHT CO. |
| References | |
| NUDOCS 8004220875 | |
| Download: ML19326C324 (4) | |
Text
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SEP 141977 Docket No. 50-313 ss Arkansas PoWr I, Light Company ATTH: Pr. utiliaa Cavanaugh, III Executive Director Generation and Construction
$IHIS DOCUMENT CONTAINS s
Post Office Box 551
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Little Rock, Arkansas 72203
_p Gentlemen Li RE: FRACTU'IE T0lGt!:ESS AUD POTEt:TIAL FOR LAMELLAR TEAP,IhG OF STEAM GEEERATOR AHD REACTOR COOLANT PUMP SUPPOP,T MATERIALS
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Euring the course of the licensing action for North Anna Power Station Unit Nos. I and 2, a number of questions were raised as to tbc potential
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for lapellar tearing and leu fracture toughness of the steam generator and reactor coolant punp support natorials for that plant. Tuo different stacl snecifications ( ASTM A36-70a and ASTM AS72-70a) covered rost of the natorial used for these supports. Toughness tests, not originally spect-fied and not in the relevant ASm specifications, were nado on those beats for which excess material was available. The toughness of the A35 steel uas found to be adequate, but the toughness of the A572 steel was relatively poor at an operating tenperature of 805.
In this case, the ar.plicant has agreed to raise the tenperature of the ASTM A572 beans in t
the staan generator su;morts to a minican temperature of 225f wrior to reactor coolant syster.: pressurization to levels above 1000 psig. Auxil-iary electrical heat will be e<aployed to surplement the heat derived from tr.c reactor coolant icop as necessary to obtain the required operating temperature of the structures.
1/ Lamellar tearing is a cracking phenonenon b+iich occurs beneath welds and is principally found in rolled steci plate fabrications. The tearing altays lies within the parent plate, of ten cutside the transforrec (visible) heut-affected zone (hAZ) cnr1 is generally parallel to the uald fusion beundary. Lanellar tsaring occurs at certain critical,icints usually within Icrge welcee structures
- wolving a high oeorea of stif tness and restraint. Restraint nay be defined as a restriction of the novenent of the various joint t
crmonents that would nomally occur as a residt of expansion and
[NrY contraction of weld netal and edjacent regions during velding.
("Lacellar Teerinc in tieldeo Steel Fabrication", The Welding h " - "
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Arkansas Power ?. Light Company SEP 14197/
Since similar catorials and designs have been used on other nuclear plants, the concerns raiseo on the supports for the 11 orth Anna plant may
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De applicable for other operating PWR plants.
It is therefore necessary to reassess the fracture toughness and potential for lamellar tearing of the steam generator and reactor coolant ptrap support materials for all operating PWR plants.
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We will require certain infomation to nake the necessary reassessment of F.
the stcact generator and reactor coolant purap support materials 'o'r your k9 olant; therefore, please provide the folicwing infomation within sixtv r
(60) days after receipt of this letter:
1.
Provide engineering drawings of the stean generator and reactor F
coolant ptnp supports sufficient to shoa the geometry of all principal elenents. Provide a listing of naterials of construction.
2.
Specify the detailed design loads used in the analysis and design of s:::,
tne supports. For each loading condition (nomal, upset, energcncy and faulted), provide the calculated maximum stress in ecch principal ele-cent of the support syster and the corresponding allovrable stresses.
3.
Describe how all heavy section intersecting menber welchents were designed to niniaize restraint and laaellar tearing. Specify the actual section thicknesses in the structure ann provide details of
!1 typical joint desicns. Stato the naxt:::ua casign stress used for tne throuph-thickness direction of plates and elencnts of rolled shapes.
4 Specify the ainicun operating temperature for the supports and
- i describe the extent to which natorial tenparatures have been ceasured 1
at various points on the supports curing the operation of the plant.
5.
Specify all the naterials used in the supports and the extent to which 0111 certificate cata are available. Descrine any suppleaental reauirements such as celting practice, touphness tests and through-thickness tests srecified.
Provice the results of all tests that may better define the properties of the naterials used.
5.
Ocscribe the weldino procedures and any special welriinc process recuirenents that were specificd to niniaire residual stress, weld cnd beat affected zone cracking and la ellar tearing of the base me tal.
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Arkansas Power t, Light Company Sgp y 4 gy
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Describe all inspections and non-destructive tests that were performed on the supports during their fabrication and installation, as well as any additional inspections that were perfomed during the life of the facil i ty.
In addition ;* the infomation requested above, please provide your own evaluation of tie fracture toughness of the steat.1 generator and reaccor g
coolant pump support naterials for your plant. Please infom us within f
thirty (30) days after receipt of this letter of your schedule for ' pro-y viding us with your evaluation. This generic request was approved by
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GAO, B-180225 (R0072), clearance expires July 31, 1980.
Approval wan I
given under a blanket clearance specifically for identified generic problens.
Sincerely, Original signed by
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/4W Ocn K. Davis, Acting Chief Operating Reactors Branch #2 i:_
Division of Operating Deactors p-cc:
Soc na.xt page
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DISTRIBUTION:
Docket i;RC PDR Local PDR ORB-2 Reading RPSnaider RMDiggs TJCarter DEisenhut Attorney, OELD I&E(3)
JRBuchanan 6
TBAbernathy i
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- NRC FORM 318 (9 76) NRCM 0240 W u4 s.novenmutut,niwTsue o,rics se7s - eas4:4
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Arkansas Power & Light Company September 14, 1977
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Cc' s eesir Phillip K. Lyon, Esquire
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House, Holms & Jewell 1550 Tower Building Little Rock, Arkansas 72201 Mr. Donald Rueter Manager, Licensing Arkansas Power & Light Company
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Post Office Box 551 Little Rock, Arkansas 72201 Arkansas Polytechnic College Russellville, Arkansas 72801 Mr. John W. Anderson, Jr.
Plant Superintendent
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m Arkansas Nuclear One
. Post Office Box 608 As-Russellville, Arkansas 72801
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