ML19254F384
| ML19254F384 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse, Arkansas Nuclear, Crystal River, Rancho Seco  |
| Issue date: | 09/05/1979 |
| From: | Garrett W SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Mosley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| Shared Package | |
| ML19254F382 | List: |
| References | |
| IEB-79-17, NUDOCS 7911090148 | |
| Download: ML19254F384 (4) | |
Text
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.. 5 P4 UTILITY DISTRICT O 6201 S Street, Bos l'430, Sacramento. California
' ' C r' A '.4 ' * ; e Septenber 5, 1979
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e Mr. fi r ia r.,
e.. l. y Nuc le.ir o<.. l.. : se, Cn-nission a
Dividi -.
vr.ictor Operations inspst ions 4 350 E.n t '.'e, t H i r.hway
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Washington, CC 20555
. I Docket Hos:
50-313 A kansas Nuclear i Unit 1 50-368 Arkansas Nuclear i Unit 2 50-302 Crystal River 3 50-346 Davis Besse l
50-312 Rancho Seco
Dear Hr. Hosley:
Acting as Chairron of the Babcock and Wilcox (B,W) Owners Group Sub-commit tee on Pipe Cracking, it is formally requested that an extension be granted h
the fa:i8itites listed above for implementation of item 2 of IE Bulletin 79-17, Pipe Cracks in Stagnant Borated Water Systems at PWR Plants. The utilities on l
u whcsc behal f this request is made are the Sacramento Municipal Utility District, Toledo Edison, Florida Power Corporation and Arkansas Power and Light.
Recent data obtained from Thr-e Mile Island Unit 1 indicates that the extent of Intergranular Stress Corrosion Cracking (IGSCC) experieaced at that facility in.304 stainless steel piping Ir much more limited than it was originally thought to be.
Of 1902 welds inspected originally, 350 contained inoications.
These 350 welds have been reinspected with a procedure which better discrircinates between actual cracks and geometrical re flec to rs.
Many of the 350 welds (including f
those in High Pressarc Injection and Decay Heat Drop Line) have been shosn to contain only geo.ctric reflectors.
It is now estimated that approxicately 30 t
welds of,t,he !302 welds inspected will be shown to contain ICSCC.
I in view of the changing nature and scope of the IGSCC data base at fu
'l Three Mile Island I, we propose that a delay of 90 days be granted for
'1 implementation of item 2.
'e' During the extension period, we will perform the following acri.ities I
to itenize and standardize the inspection processes and to identify the cause I
of cracking:
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1.
In stagnant portions of engineer ~ed safety systems, visual s
t-examinations of accessible welds will be conducted h
monthly to veri fy system integrity.
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..E wr kh Mr. florman C. Mosley Page Two September 5,1979 1.
Con tinued Where possible, these examinations will be l
conducted in conjection with monthly pump operability testing with the system at service pressure.
2.
Analyze the discrimination procedure currently in use at Three Mile Island 1 and other procedures utilized in the past for the detection of IGSCC to obtain an understanding of how basic parancters such as inspection l
frequency, transducer size, inspection angle, focusing, inspection technique and weld preparation af fect inspection of 304 stainless steel for IGSCC.
Results of this ef fort would be utilized to optimize the inspection procedure on a plant specific basis and to prove procedure accuracy and adequacy.
3 Evaluate and resolve indications at Three Hile Island I.
This evaluation would include definition of the actual extent of IGSCC at Three Mile Island I and an analysis of the source of the cracking.
It should be noted that the Owners Group has
, offered to assis: Hetropolitan Edison in resolution of the Three Mile Island 1 situation.
4.
Development of consistent sempting plans for use at all fccllities.
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During conversations with NRC Staff on August.10, 1979, sampling plans were discussed. We under-stand that a basic sample of 10% of the pSysically accessible welds is to be taken and that the distribution of welds selected be skewed based on a heirarchy of (1) pipe cijcmistry (i.e. carbon content), (2) pipe wall thickness. (3) system function, and (4) piping configuration and layout. We suggest,that based upon final results i
i from Thice Mile Island 1 (see i tem 3 above) that
[
both the sample size and basis may change.
- Further, we feel that if all plants are inspected with plans 3
developed utilizing a common philosophy, the Inspection results will be more.casily compared and i n te rp re t ed.
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Mr. Nora n C. Hosiay Page Three September 5,1979 5
Definition of a schedule for inipiementation of item 2.
A realistic assessment of the time involved to perform required examinrtions and manpower availability must be made. The magnitude of the inspection task and manpower available dictates that cooperative scheduling between all facilities be utilized. These assessments may indicate that the time currently allowed by the NRC for completion of the required e,
examinations be changed.
6.
Determination of an adequate sampling plan for use if a crack is found.
.a Since the initital sample of 10% is to be preferentially chosen from welds where IGSCC is most likely to occur, immediate increase of the sample size to 100% when a crack is found would appear to be somewhat extreme.
Based on completion of the initital 10% sample.
an understanding of the problem can be gained an an adequate sampling plan based on statistical gy confidence and engineering judgement can be made.
For example, the remainder of welds in the same
" family" of welds could be the first step of an additional inspection sample. Another example might be to concentrate additional inspection on the Nuclear Class I portions of engineered safeguards i
systems.
During this time ' frame, technical and procedural items regarding IE Bulletin 79-17 can also be clari fied. These items include the foliciwing:
1.
Definition of reporting requirements for use with inspection procedures. This item must be completed early and the information fed to the utilities because It impacts the adequacy of procedures which may be selected for use in performir.g the equired exam-Inations.
It should also be noter' that reporting requi renents may di f fer between of f ferent systems.
2.
Definition of when item 2c is to be implemented if cracking is identified during inspection of the original sample.
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,4 Mr. Norman C. Mosicy Page four September 5,1979 3
Determination of whethe r or not Sect ic. 71 evaluation techniques are allowable t r.r use in acceptance of crack indications or alternatively, whether an augmented inspection program night be allowed rather than stipulating that cracks must be repai red.
4.
Determination of philosophy for resolution of construction / fabrication defects pre-vlously undetected.
5 Reduction of data supplied under item 1 of the Bulletin to assist problem definition.
The successful resolution of the aforementioned items will provide the NRC staff with the necessary information to make the most appropriate decisions regarding a timely and effective inspection plan for the borated water systems piping.
Organization of all utilities and informing them of our efforts has begun with technical assistance being provided by Electric Power Research Institute (EPRI). NRC will be kept informed of efforts in this area.
We are concerned with the implications of inspection results at Three Mile Island I and want to develop sampling plans and in5pection procedures with which we c.an assure ourselves and the NRC that we have resolved any potential proolems. 'We submit that the delay in implementation of item 2 will allow us the tire to develop sound programs and procedures which are based on evaluation of_ all available data and that this delay will not endanger the public health and safety. Your prompt consideration and reply will be greatly appreciated.
I f you have any questions, please feel free to contact me.
Respectfully submitted, y
iff
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lh V. B. Garrett M Plant Mcchanical Engineer Rancho Seco Nuclear Generating Station ChbrmanB&WOwnersGroup Subconrait tee on Pipe Cracking VBG:sc cs:
Mike Whlte - Arkansas Power (, Light ttipGH5Blu Tlorida Power Corp.
Chuck Daf t - Toledo Edison Darrell Eisenhut - NRC/lcE Warren Hazzleton - NRC g
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Ed Jordon - NRC Jack Uhl - BtV Vince Noonan - NRC' NRC Region V (Rant... Seco Resident)
.