TXX-4300, Forwards Response to NRC 840828 Request for Addl Info Re Max Interpass Temp Control & Nonelevated Preheat Control Based on Violations Noted in Insp Repts.Procedures for Welding on Notch Toughness Matls Will Be Revised
| ML20112F960 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 09/17/1984 |
| From: | Clements B TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | Denise R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| Shared Package | |
| ML20112F954 | List: |
| References | |
| TXX-4300, NUDOCS 8501160118 | |
| Download: ML20112F960 (3) | |
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September 17, 1984 TXX-4300 Mr. Richard P. Denise, Director Division of Reactor Safety and Projects U.S. Nuclear Regulatory Connission, Region IV 611 Ryan Plaza Drive, Suite 1000 Docket Nos. 50-445 Arlington, TX 76011 50-446 C0iANCHE PEAK STEAM ELECTRIC UATMN UNITS 1 AND 2 WELDING ALLEGATIn:4S ADDITIONAL RESP NSE FILE NO.:
10066.5
Dear Mr. Denise:
In my letter of June 15, 1984 to Richard P. Denise, Texas Utilities Generating Company ("TUGCo") responded to MlC Staff questions regarding, among other things, (1) maximum interpass temperature controls for welding on notch toughness materials and (2) nonelevated preheat control.
In that letter, we provided detailed infonnation demonstrating the effectiveness and adequacy of procedural controls concerning these issues at the Comanche Peak Steam Electric Station ("CPSES"). By letter dated August 28, 1984, from R.L. Bangart to Michael D. Spence, the NRC Staff requested additional information regarding these two issues. The attached response provides the requested infonnation.
We trust you will find this information helpful in expediting closure of these issues. Please advise if you require further information.
Very truly yours, b
BRC:tig cc: Mr. John Collins U.S. NRC - Region IV D.M. Hunnicutt T.A. Ippolito G. Mizuno 8501160118 841213 PDR ADOCK 05000445 0
PDR A DIVINION OF TEXAN l'181 ITREN ELKt'TNit' Cubtl*ANY
TXX-4300 September 17, 1984 RESPONSE TO STAFF'S ADDITIONAL QUESTIONS REGARDING MAXIMtM INTERPASS TEMPERATURE CONTROL AND NONELEVATED PREHEAT CONTROL Maximum Interpass Temperature During recent discussions regarding this issue, the RC Staff has stated that in view of its independent investigations and the detailed infonnation provided in say June 15 letter, there is reasonable assurance that maximum interpass temperature requirements for welding on notch toughness materials have not been exceeded so as to call into question the structural integrity of any weld joint.
However, the Staff believes that to enhance further the welding program at CPSES and to preclude future questions regarding this issue, additional and more easily verifiable controls should be considered, e.g., requiring that all welders use temperature indicating devices between passes to provide sitive visual assurance that maximum interpass temperatures are not exceeded.
We do not believe that such controls are necessary to assure compliance with applicable ASME and EC requirements; however, to resolve this issue and provide further conservatism in the welding program, we will revise applicable welding procedures to make clear that on the materials of concern a positive indicating device (such as temperature indicating crayons or contact pyrometers) will be used by welders between each weld layer to provide visual assurance that the maximum interpass temperature is not exceeded.
In parallel, affected welders will be trained on this requirement and retrained on the use of such devices.
In addition, surveillance of interpass temperature control by both Welding Engineering Department and QA/QC personnel will provide assurance that this new requirement is being implemented.
(In this regard, QC has been conducting twice weekly documented surveillance of interpass temperature control since March 9,1984.)
1 As stated in my letter of June 15, tests have demonstrated that if welding occurs within the normal parameters set forth in the applicable welding it is impossible to procedures and appropriate weld cleaning occurs 6 exceed the maximtsn interpass temperature of 500 F for notch toughness material s.
(It must be remembered that the maximum interpass temperature could have been set at 6000F and still been within applicable Code requirements without additional welding procedure qualification. Further, the maximtsn interpass temperature design specification for this welding is 7000p.)
TXX-4300 September 17, 1984 Nonelevated Preheat Control During recent discussions regarding this issue, the NRC Staff has stated that in view of its independent investigations and the detailed information regarding preheat provided in my June 15 letter, there is reasonable assurance that nonelevated preheat requirements have not been violated so as to call into question the structural integrity of any weld joint. However, to enhance further the welding program and to preclude further questions regarding this issue, the Staff believes that additional and more easily verifiable controls should be considered, e.. providing thermometers to welders when the ambient temperature drops below 0 F to assure that welders are aware of ambient temperature conditions and have a more readily verifiable method (instead of the " hand-warm" criterion) of detennining when the temperature of the joint drops to the point where preheat is required {for ASME and AWg) shielded metal 0
arc welding of low carbon steels, 60 F and 70 F, respectively We do not believe that such controls are necessary to assure compliance with applicable ASME and NRC requirements; however, to resolve this issue and provide further conservatism in the welding program, appropriate construction procedures at CPSES will be revised to require calibrated thermometers to be issued to welders whenever the ambient temperature outside the weld 0
distribution stations drops below 70 F.
Welders will be required to check the temperature of weld joints in such cases to determine if preheat is required.
Affected welders will be trained on this requirement and use of the thennameters.
In addition, surveillance by Welding Engineering Department and QA/QC personnel will provide assurance that this new requirement is being implemented.
(In this regard, twice weekly documented surveillances of preheat controls have been conducted by QC since March 9,1984.)
2 It should be noted that procedural requirements in this regard exceed those required of the applicable Codes.
For example, pursuant to the ASME Code, without further weld procedure qualification preheat is not required 0
0 0
until the weld joint is below 50 F (50 F below the 100 F qualification temperature). On AWS materials, pursuant to the Code, preheat is not 0
required until the joint temperature is below 32 F.