NRC Generic Letter 1982-26
| ML031080494 | |
| Person / Time | |
|---|---|
| Issue date: | 11/12/1982 |
| From: | Eisenhut D G Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| NUREG-0744 GL-82-026, NUDOCS 8211160047 | |
| Download: ML031080494 (2) | |
NOv 1 2 1982TO ALL POWER REACTOR LICENSEES (EXCEPT FT. ST. VRAIN)Gentlemen:SUBJECT: NUREG-0744 REV. 1; (GENERIC LETTER NO. 82- 26 ) -PRESSURE VESSEL MATERIAL FRACTURE TOUGHNESSAppendix G to 10 CFR 50 specifies fracture toughness requirements forpressure retaining components, fabricated from ferritic materials, inthe reactor coolant pressure boundary of water cooled reactors. Inthe event a pressure retaining component falls to meet the materialtoughness requirements during its service life due to neutron radiationembrittlenent, continued operation of the component is permissibleprovided certain requirements, specified In Section V.C of Appendix G,are satisfied.One of the requirements of Section V.C is that a fracture analysis ofthe component is to he performed to demonstrate the existence of ade-quate margin for continued operation. The proposed progran for satis-fying this requirement is to be submitted to the USNRC for review andapproval at least 3 years prior to the date fracture toughness levelsare predicted to no longer satisfy requirements.Appendix H to 10 CFR 50 specifies the surveillance program which allpower reactor licensees must maintain to monitor irradiation-inducedfracture toughness changes. Impact data from this program are used toadjust the reference toughness curve for irradiation effects throughthe application of the adjusted reference temperature. The CharpyV-notch 50 ft-lb level is used to determine the temperature shift;therefore, when the upper shelf energy falls below 50 ft-lb, therequirements of 10 CFR 50 Appendix G are no longer ret.To provide guidance to licensees who may be required to submit afracture analysis to Justify continued operation of a pressurevessel, the USNRC has developed an elastic-plastic fracture mechanicsanalytical procedure. This analytical methodology is presented inNUREG-0744, Revision 1 (Office of Management and Budget ClearanceNumber 3150-0011), a copy of which is enclosed with this letter.3211160047OFFICEO............ ... ........................ ........... .................... ............. ........................... ........................ ............ ................ ........ ................ ........................SURNAME t.... ........................ ............ ;................ ................................ ........................ ............ ................ ........ ................ ........................DATEt............ ... ........................ ........... ............................ ........................ ................................ ............ ................ ........ ................ ........................NRC FORM 318 (t0 80) NRCM 0240O.FFICIA L RE C OR.D C OPYUSGPO: 1981-335-960
ftU. iALL POWER REACTOR LICENSEES -2-This document presents one methodology which is acceptable to theUSNRC staff for meeting the requirement for a fracture analysis withsufficient accuracy and reliability to demonstrate adequate margins forcontinued operation in accordance with Section V.C.3 of Appendix G to10 CFR 50. Licensees, however, need not employ this specific fractureanalysis methodolog~y and may submit an analysis based on other tech-niques for NRC review and approval.Available evidence reveals that the upper shelf energy of a number ofpower reactor pressure vessels may fall below the 50 ft-lb level beforethe end of their design life unless measures such as revised fuel manage-ment schemes are instituted. It is likely that several licensees nayelect to subrilt fracture analysis to support continued operation. Alllicensees are encouraged to review NUJREG-0744. Revision 1 and considerits application in those cases where it may be necessary to submit afracture analysis to the NRC for review and approval.Sincerely,original signed byParll. EisenhuatDarrell Gi. Eisenhut, DirectorDivision of LicensingOffice of Nuclear Reactor RegulationEnclosure:NUREG-0744, Rev. 1ICService List:W/o enclosureA ___ _ ___I R 4:D:DL D:DST _ 0.......... ... ...........OFFICE~ .AtF .0.. asS a D l s nitSURAMEi......... 4.. RSU N ~ ~ .......i...-....h..44.... ..8 ... ............. ............. .............AT 11/ / 2 a b 1 / 8lit82 2 /.... 11 /1 82 11 / 3 ... ..... ...... ............N R C TFO R .31 8 .. .... ......... ... .. ....02 4 0... .F F. C I A L..R. ..... ..... W G P O : ..........NRC FORM 318 (10-80) NRCM 0240OFFICIAL RECORD COPYUSGPO: 1981-435-9w