ML20150D331
| ML20150D331 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/11/1988 |
| From: | NRC OFFICE OF SPECIAL PROJECTS |
| To: | |
| Shared Package | |
| ML20127A683 | List:
|
| References | |
| NUDOCS 8803230353 | |
| Download: ML20150D331 (9) | |
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%e, UNITED STATES O N M jl. j, se"'
E I NUCLEAR REGULATORY COMMISSION g vf 5 WASHINGTON, D. C. 20555
.....f SAFETY EVALUATION BY THE OFFICE OF SPECIAL PROJECTS NRC WELDING CATEGORY - FILLER MATERIAL CONTROL TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR POWER PLANT, UNITS 1 AND 2 DOCKET NOS. 50-327 AND 60-328 1.0
Subject:
NRC Welding ~ Category "Filler Material Control" TVA Category: WELDING TVA Subcategories: WE-50301, WE-50312, WE-50914, WE-50907, WE-50821 WE-50323, WE-50399, WE-50899 The employee concerns were evaluated by TVA as potentially safety-related and applicable to the Sequoyah site or as potentially applicable to the Sequoyah site on a generic basis. TVA established the Welding Project to formulate a program for each nuclear plant site to address the employee concerns related to TVA's welding program.
Many of the concerns which originated at the Watts Bar Nuclear Plant were determined by TVA as possibly being generic, and therefore applicable to all of the TVA nuclear plant sites.
For the Sequoyah site, the TVA Welding Project is divided into two phases.
Phase 1 is a review of the records to determine if there are any problem indicators.
Most of the final element reports which are TVA's evaluation of employee concerns with a common issue (s) were written on the basis of the Phase 1 efforts.
Phase 2 involved a review of ISI and LER records, an audit by Bechtel of the welding program records, and a physical reinspection of specific weldment populations whose samples were selected on an engineering and logic basis.
The NRC staff formed a Welding Task Group with representatives from the Offices of Nuclear Reactor Regulation (NRR), Inspection and Enforcement (ISE),
and Region II.
The Task Group established an Expert Welding Team through an l
NRR Technical Assistance contract with Brookhaven National Laboratory (BNL).
BNL provided a Technical Evaluation Report (TER) which summarized the opinions of the Expert Welding Team concerning the various welding issues and the actions taken by TVA as addressed in TVA's Element Report drafts of mid-1986.
The NRC Welding Task Group also performed independent visual, surface and volumetric reinspections of weldments at the Sequoyah site with help of Region I personnel operating out of the NDE van.
The TER and the Inspection Reports were incorporated in the initial Welding SER issued to TVA on November 11, 1986.
This SER is being provided to address in more detail the individual employee concerns and the changes made of the individual employee concerns declared generic to the Sequoyah facility since the initial staff Welding SER.
The staff believes that there are five essential elements which must be functioning for a welding program to be viable.
The staff placed each of the individual employee concerns into one of these essential element 8803230353 880311 PDR ADOCK 05000328 i
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i l categories. A miscellaneous category was established to cover those aspects which are not directly related to the welding program. These program essential element categories are as follows:
Welding Procedures Welder Qualification / Training Welding Inspection Weld Design and Configuration Filler Material Control Mis::ellaneous/0ne of a Kind The staff's approach has been to group similar employee concerns within an essential element to establish an "issue" or "issues".
The staff reasons that the particular issue (s), if valid, and significant, would generate an adverse condition in the hardware.
As part of the overall program for reassessing the TVA welding program implemented during plant construction and operations, TVA and the NRC staff conducted reinspections at the Sequoyah site to determine 1), that the licensee's corrective actions for resolving the issues raised by the employee concerns were being satisfactorily implemented, and 2), that the hardware was suitable for service. NRC staff inspections and evaluations were performed on TVA's record audits program, personnel performing TVA's audits and reinspections, and TVA's records.
Tne employee concerns considered in NRC Essential Element category "Filler Material Control" are as follows:
EMPLOYEE TVA FINAL ELEMENT BRIEF DESCRIPTION OF CONCERN CONCERN NO.
REPORT RESPONDING TO CONCERN EX-85-021-001 WP-01-SQN INADE0VACY OF WELD R0D ISSUANCE AND ACCOUNTABILITY.
EX-85-039-001 WP-01-SON NO ADE0VATE ACCOUNTABILITY OF KELD RODS, i.e., RCD STUBS AND UNUSED RODS.
LACK 0F PORTABLE OVENS FOR WELD R00 STORAGE AFTER ISSUANCE OF MATERIAL.
IN-85-337-002 WP-01-50N INSUFFICIENT WELDING R00 CONTROL.
NO PORTABLE OVENS ON SITE TO MAINTAIN ELEVATED WELD R00 TEMPERATURE. WELDERS CERT IS NOT ALWAYS CHECKED BEFORE ISSUING R0D IN-85-424-004 WP-01-SQN QA TRAINING CLASS INFORMED CRAFT THAT STEAMFITTERS COULD WITHDRAW AND CONTROL WELD R0D IF THEY HAD A WELDER SIGNED WELD SLIP AND THE WELDER'S CARD.
. EMPLOYEE TVA FINAL ELEMENT 'BRIEF DESCRIPTION OF CONCERN CONCERN NO.
REPORT RESPONDING TO CONCERN IN-85-424-006 WP-01-SON NO ACCOUNTABILITY OF WELD ROD.
IN-65-424-007 WP-01-SON LACK OF WELD R00 CONTROL.
- 1N-85-672-003 WP-01-SQN WELD R0D TURN-IN SLIPS ARE THR0WN AWAY IN-86-047-001
- WP.14-SQN A SYSTEM IS NEECED TO VERIFY AND DOCUMENT THAT A WELDER HAS RETURNED UNUSED RCD STUBS. A RECEIPT SHOULD BE PROVIDED TO THE WELDER S0 THAT HE CAN PROVE HE RETURNED R00.
IN-86-150-001 WP-01-SON TFERE IS NO PROGRAN FOR MATERIAL TRACEABILITY OF WELDING R00. WHEN WELDING R00 IS DRAWN IT COULD BE USED ANY PLACE IN THE PLANT. MATERIAL TRACEABILITY IS NOT ATTEMPTED.
IN-86-167-091 WP-01-SON h0 TRACEABILITY OF WELD RODS TO ACTUAL JOB PERFORMED WI-85-041-001 WP-01-50N WELD R0D CONTROL IS INADE0VATE. ROD SLIPS ARE NOT RETAINED AS RECORDS AND HEAT / LOT NUMBERS AND LOCATION OF USE ARE NOT RECORDED.
WI-85-053-004 WP-01-SQN WELD ROD CONTROL DOES NOT SATISFY CODE RECUIREMENTS XX-85-068-006 kP-01-SON WELD R0D CONTROL DOES NOT SATISFY CODE REQUIREMENTS IN-85-453-009 WP-01-SON WELDERS FREQUENTLY GIVE WELD R00 TO OTHER WELDERS.
IN-85-454-004 WP-01-SQN WELDERS FRE0VENTLY GET RODS FROM EACH OTHER INSTEAD OF WITHDRAWING FORM RCD ROOM.
IN-85-234-001 WP-01-SON WELD RODS NOT REQUIRED TO BE KEPT Ih R0D OVENS AFTER ISSUANCE.
IN-85-352-002 WP-01-SON NO PORTABLE OVENS ARE USED AT WA*TS BAR.
RODS'CAN BE KEPT FOR AN ENTIRE SHIFT AND RETURNED FOR LATER USE.
t qs EMPLOYEE TVA FINAL ELEMENT BRIEF DESCRIPTION OF CONCERN j
CONCERN NO.
REPORT RESPONDING TO CONCERN IN-85-424-001 WP-01-SQN NO PORTABLE OVENS USED OR REQUIRED.
IN-85-426-001 WP-01-SON PORTABLE OVENS ARE NOT REQUIRED.
IN-85-441-003 WP-01-SON h0 FORTABLE R0D OVENS.
IN-85-247-001 WP-12-SCN 7018 RODS ARE OF POOR OVALITY WHICH WILL CONTRIBUTE TO POROSITY AND PINHOLES.
IN-85-411-002 WP-12-SQN WELDING RODS (7018,3/32 ONLY)ARENOT OF GOOD QUALITY.
IN-85-600-001 WP-12-SQN E7018 WELD ELECTRODE PURCHASED BY TVA ARE OF P0OR QUALITY. FLUX FALLS AND FLAKES OFF ROD.
- DHT-85-001 WP-21-SON WELDING RODS ARE OF P00R OVALITY.
PROCEDURES CALL FOR E705-3 RODS BUT ONLY E7 05-6 RODS ON SITE.
XX-85-013-001 XX-85-013-001 309 WELD R0D WAS USE0 TO WELD 316 STAINLESS STEEL AT SECUOYAH UNIT 1.
XX-85-041-001 I-85-756-SQN WRONG KELD R0D USED TO JOINT CARBON STEEL PIPE TO STAINLESS STEEL PIPE.
- XX-85-124-001 WP-23-SQN BURYING OF UNUSED WELD R00.
This final element report also covered employee concern IN-86-158-006 which is about apprentice welders being able to weld.
This concern will be addressed in NRC Welding ~ Category "Welder Qualification / Training".
Subsequently, TVA's Welding Project judged some of these employee concerns (and others originally listed as being generically applicable to Sequoyah) as being Watts Bar unique because of reference to Watts Bar or its features, locations, etc.
The following employee concerns which were originally listed as being applicable to Sequoyah, were subsequently judged by TVA's Wolding Project as not being applicable to Sequoyah.
The staff has reviewed these concerns and 1
have determined that these concerns are duplicates of other concerns already applicable to Sequoyah, and that their removal does not significantly change the distribution of concerns / issues within the five NRC essential element categories.
These concerns are further discussed in the NRC Miscellaneous /
One of a Kind category.
DHT-85-001 IN-85-501-001 IN-85-672-003 IN-86-16~-001 XX-85-124-001
._ y s
, 2.0 Sumary of Issues The issues involved with the 19 employee concerns covered in WP-01-SQN are sumarized as follows:
The Weld Material Control Program does not meet code requirements.
The context of this issue is that the concerned individuals are referring to the overall traceability of welding materials from procurement until the materials are consumed in the final weld.
Returned weld material is not accounted for adequately.
Lack of portable electrode holding ovens.
' Collection of moisture in electrodes due to lack of portable electrode holding ovens.
The issues involved with the three concerns covered in WP-12-SON are sumarized as folicws:
E7018 electrodes are of poor quality.
Poor quality electrodes contribute to pinholes and porosity.
E7018 3/32-inch electrodes are of poor quality.
Electrode core wire is not centered and ficx falls off.
The filler material control issue involved with the concern IN-86-158-006 as covered in WP-14-SON is sumarized as follows:
A system is needed which will provide the welder with a receipt which can prove welding material was correctly returned to the rod issue centers.
The issues involved with concerns DHT-85-001 as covered in WP-21-SQH are sumarized as follows:
Weld procedures call for E70S-3 but only E705-6 is available on site E7018 electrodes are of poor quality The issue involved with concern XX-85-013-001 as covered in ERT-XX-25-013-001 is sumarized as follows:
309 weld rod was used to weld 316 stainless pipe at Sequoyah Unit 1.
The issue involved with concern XX-85-041-001 as covered in NSRS I-85-756-SON is summarized as follows:
At Sequoyah, a weld was made in '79 or '80 in the diesel generator building, Unit 1, using the wrong type rod to weld carbon steel pipe to stainless steel pipe.
A cover pass using the correct rod was run over the existing weld.
No further information is available.
i 1
t,
The issue involved with concern XX-85-124-001 as covered in WP-23-50N is summarized as follows:
Several 55 gallon drums of unused electrodes were buried at Sequoyah 3.0 Evaluation i
The purpose of establishing categories and issues was to group the employee concerns of similar subject matter so that they could be uniformly addressed.
We found that TVA occasionally did not group all of the employee concerns of a given issue in one final element report.
For instance, the issus of welding electrodes of poor quality are present in both WP-12-SQN and WP-21-SQN.
The number of employee concerns relating to a given issue was regarded as an indication of how much effort should be applied to the issue; the more concerns, the more attention was given to the issue. A review of the employee concerns determined that the majority of the employee concerns applicable to Sequoyah involved record and paperwork aspects of the welding program anc'very few had to do with actual welds.
An assessment of TVA's final Element Reports addressing the employee concerns was made by the staff. Generally, the staff agreed that TVA had adequately addressed the concerns. However, the emphasis on our efforts in evaluating the employee concerns has been the hardware, i.e., did the hardware conform to standards to which TVA comitted to, and if not, were the welds satisfactory for service.
In addition, the staff assessed the programmatic corrective actions taken by TVA to assure the welding program was adequate for future work.
The issues related to filler material control were generally covered by TVA in their Phase 1 effort, the record review.
TVA's Welding Project, as a Phase II j
effort, had the Bechtel Corporation perform an audit of Sequoyah's welding program records that included filler material records.
Thirteen of the 19 employee concerns addressed in WP-01-SON are about filler material control, i.e., the lack of control, accountablity, and traceability.
The weld material control program at the Sequoyah facility has been reviewed by NRC Region II inspectors many times during the course of cunstruction and operations.
The premise of the TVA program is that all material brought on site is purchased such that the filler material meets the requirements of the major fabrication codes (ASME and AWS).
TVA requested and received NRC approval (AEC letter dated July 17, 1974, subject, "Control and Identification of Welding Materials") for nct maintaining traceability of filler material to the end point of usage.
The staff stated that, "licensees are required to have adequate control measures to assure that the correct specified materials 6re used.
This assurance would generally be achieved through the control procedures for receipt, storage, and issuance of welding materials".
The Expert Welding Team noted that the issues of unused weld filler materials not being returned, the exchange of weld material between welders, and the storage of unused electrodes, by welders fcr later use (and attendant moisture pickup) were not addressed in TVA's Final Element Reports WP-01-SON and WP-14-SON.
TVA only stated that the welders were instructed in the procedures for control and return of electrodes and that welders were subject to disciplinary action if caught violating procedures.
s l It is possible that there was a progranrnatic breakdcwn in filler naterial control in TVA's welding program at the Sequoyah facility.
There are many employee concerns about exchange of electrodes between welders, and that there was no positive control of unused electrodes.
If true, it is evident that there were an indeterminate number of electrodes circulating outside of the filler material control system.
The worst consequences would be that the electrodes would pick up an excessive (more than a specified quantity in the filler material specification) amount of moisture in the flux. Moisture pickup by the flux coating of welding electrodes (rods) can be a problem because the moisture, in the presence of the arc during welding, can induce hydrogen in the molten weld metal puddle.
When the weld metal freezes and cools to room temperature, the hydrogen can cause cracking in steel weldments in the heat affected zone of the wcld.
However, from a technical standpoint, the low carbon-manganese (C-Mn) construction steels used at Sequoyah are not as susceptible tc hydrogen cracking as more highly alloyed steels.
This is because the heat affected zones would not be as hard, therefore, allowing the hydrogen to diffuse out of the heat affected zones and avoid the hydrogen pressure buildup and subsequent cracking.
Further, total hydrogen content of E7018 electrodes due to cellulose content and moisture pickup has been demonstrated to be low compared to other electrodes by several other construction firms at other nuclear plant sites.
TVA performed similar testing for moisture content pickup due to extended atmcspheric exposure of E7018 electrodes used at their facilities.
This testing was done after construction was complete at the Sequoyah facility, however it would apply to welding performed by Nuclear Operations.
The TVA and NRC reinspections found no evidence to support the issues raised by these employee concerns existed to the peint of causing damage to welcments.
No cracks were found indicating excessive moisture pickup by the welding electrodes, in addition, other employee concerns, such as IN-85-672-003 and IN-85-424-007, demonstrate that TVA was maintaining a filler material control program as the individuals expressing these concerns also mention in their employee concern that discipline actions were being taken by TVA when filler material control procedures were not followed.
Region II inspecturs performing inspections during Sequoyah's construction phase rated Sequoyah about average for filler material control when ecmpared to other nuclear plants under construction in the same time frame.
Four of the seven employee concerns in WP-01-SQN are about the lack of portable rod ovens at Watts Bar.
The TVA Employee Concern Program judged these concerns as possibly beino applicable to Sequoyah.
For Watts Bar, TVA established an electrode moisture testing program to monitor moisture content pickup within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to allcw the electrodes to be used in the field for an entire shift without roc ovens.
These concerns could have been generated by welders who worked at Sequoyah where rod ovens were required, and then transferred to Watts Bar where the rod evens were not required.
Their lack of knowledge about the other controls on electrode moisture content at Watts Bar could have been the cause for these concerns being generated.
In WP-01-SCN, TVA states that
. the procedures required use of rod ovens, and the audit by Bechtel demonstrated that the procedures were implemented correctly.
There was a daily surveillance program which monitored the implementation of welding procedures, including the use of rod ovens.
There appears to be sufficient evidence to show that rod ovens were generally used at Sequoyah and that structures were not affected if any instances occurred where filter rods were left out longer than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
The Welding Expert Team, during their site visits to Sequoyah, heard about lack of rod ovens being a problem in the early days of construction at Sequoyah, i.e., before the 1974 Stop Work Order.
The Team, in their TER, expressed their belief that this should have been addressed.
It is noted in the TVA Welding Project, Sequoyah Nuclear Plant, Phase I Review, Volume II, 1
Sect'.on 2, page 3 to 4, that 1974 was the cut off date for consideration of all issues because resolution of the Stop Work Order answered all questions
)
on site production at that time.
The lack of portable rod ovens was definitely a problem prior to 1974, and was addressed at that time.
The issues of poor quality electrodes was adequately addressed by TVA in that they demonstrated corrective actions being taken when poor quality electrodes were encountered.
It is well known that electrodes of different manufacturers perform differently and this may account for some of the employee concerns about electrode handling characteristics.
Electrode flux eccentricity, which will affect handling characteristics, was detected and addressed by the TVA Welding Staff at the time of use.
The disposition of the problem by TVA of returning the remainder of the lot to the vendor was adequate.
The original field visual inspection should have detected those welds made with electrodes whose handling characteristics were degraded to the point of affecting weld quality.
TVA performed adequate investigations on the use of incorrect ele:.W&s (XX-85-013-001 and XX-85-041-001) and the engineering solutions are acceptable.
The burying of unused electrodes to dispose of them is an acceptable approach and provided reasonable assurance that these electrodes would not get back into the electrode handling system.
The use of E70S-6 on production being based upon a procedure qualification using E705-3 filler material is an acceptable practice by the code.
4.0 CONCLUSION
S The staff conclusion stated in the Welding SER, dated October 30, 1986, was that the filler material control aspect of their welding program was functioning to some extent.
The results of reinspections by TVA and NRC, demonstrate that programmatic deficiencies in filler material control did not affect the suitability of the hardware.
It appears there were prograrmatic problems of individual welders who exchanged electrodes, or stored them for future use.
TVA cited their procedures which addressed handling of electrodes, and stated that if the procedures were violated, the welders were subject to discipline.
Some of the employee concerns mentioned the use of discipline being used to enforce returned rod receipt procedures while the rod receipts
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9 apparently had no importance.
We believe that TVA had a filler material control program which was in control, and that there were individual instances of limited occurrence where welders who did not follow the procedures were subject to discipline.
The results of the reinspections demonstrate that weldments at this facility are acceptable for service and verified that the original inspections were effective in identifying and correcting any cracking that may have been present in the weldments.
The issues of no portable rod ovens (subsequent to the 1974 Stop Work Order) and lack of filler material accountability were adequately addressed by TVA. The employee concerns about poor quality electrodes were investigated by TVA and the responses are reasonable. The investigations on the use of incorrect electrodes and the engineering resolutions were acceptable.
For the Sequoyah site, TVA's approach to filler naterial control (traceability, accountability, and conditioning) was adequate.