ML20009B458
| ML20009B458 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 02/15/1978 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | Kniel K Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20009B448 | List: |
| References | |
| NUDOCS 8107160026 | |
| Download: ML20009B458 (2) | |
Text
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4 NUCt.EAP RE20LATERY C0MM;sslON
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- - MEMORANDUM FOR:
K. Kniel, Chief, Light Water Reactors Branch No. 2, NRR FROM:
K. V. Seyfrit, Assistant Director g 6f
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for Technical Programs. IE
SUBJECT:
PIPE STORAGE PP", tit ES AT LIMERICK GENERATING STATION, UNIT'
- . i AND 2 REF
(1) K. Kniel Ltr Philadelphia Electric Co.,
July ~ 4,1977, same subject (2) Memorandum from R. T. Carlson to K. V. Seyfrit, e. h, 9
April 31,1977, same subject (Airs DW %
(3) Philadelphia Electric Co. Ltr to X. Kniel.
November 4,1977, same subject Your letter (Ref.1) directed the licensee to discontinue the practice of outside storage of carbon steel piping without protective end caps in that such practice deviated from 10 CFR 50 Appendix B, Criterion 13 and Regulatory Guide 1.38 requirements.
This decision was partially based on the determination by IE field inspections that the licensee's onsite corrosion study was not sufficiently conclusive to justify such storage practice (Ref. 2).
The licensee's response to OPM (Ref. 3) stated that outside storage of uncapped carbon steel piping would be continued and transmitted certain corro-sion test data to support t!ieir alternate storage method.
We hsve reviewed the lic*ensee's corrosion test data along with the inspector's original field notes, annoted copies enclosed, and offer the following comments for your consideration in resolving the issue.
A comparison of Yables 2, 3 and 4 of the licensee's. esponse with the inspector's field notes (Enclosures 1 through 6) shows certain corrusion study results which was presented to IE initially and rejected due to poor data correlation and inconclusive results.
Within this context four additional tables presented to IE originally for review were omitted from the November 4,1977 letter to DPM (Enclosures 7 through 10).
Notably, Enclosures 7 and 8 reflect limited thickness measurement st 4 es which show a calculated corro-i sion rate double that for uncapped pipe versus capped pipe.
Similarly, f
CONTACT:
W. J. Collins TP 49-28180 0b 9
85.07160026 810708
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POR ADOCK 05000352 p
K. Kniel 2-FEB 151978
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Enclosures 9 and 10 reflect coupon weight.-loss results which also indicate a doubled corrusion rate for uncapped versus capped pipe. '
However, further inference can be drawn from the data that pipe.-i corrosion losses are minimal and the required wall thickness is not compromised irrespective of environmental exposure conditions :
with respect to time.
It is worth noting also that an evaluation -
of the potential for pitting damage, an essential parameter, was apparently not taken into account in the studies.
It is generally recognized that corrosion pitting is an autocatalytic process and its self-stimulating behavior can lead ta localized corrosion rates having a much greater damaging effect in comparison to the general.
corrosion wastage evaluated. Moreover, pitting attack due to its localized nature occurs without significant metal losses (as a function of depth of penetration) and therefore, conventional weight-loss tests cannot be used for evaluation or comparison. purposes.
Of further concern, such degradation can be relatively obscure to detection and evaluation Ly customary visual inspection tech-nioues. This would be especidly true when considering accessibility restrictions due to pipe spool sizing and/or configuration variability.
The licensee indicates (Ref. 3) that an alternate storage method for uncapped carbon steel piping has been implemented which calls for " inspections" of pipe conditions during storage and after post-storage cleaning prior to installation. We note, however, that certain piping spools will have rain hoods installed which does,'-
not eliminate the risk of water intrusion and entrapment.
In view of this fact and the questionable variance in the corrosion study results, we believe the licensee should consider ultrasonic examina-tion (corrosion cvaluation/ thickness gaging) in conjunction with post-storage cleaning of these pipe spools on an evenly distributed sampling bases with particular emphasis on areas inaccessible for visual examination. Procedures appropriate to U.T. performance should be established and examination results properly referenced to pipe spool inspection reports. We feel tnis examination can be performed effectively and would be a practical Q.C. measure in resolving this issue.
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Karl V. Seyfrit, Assistant Director l
for Technical Programs I
Division of Reactor Operations Inspection
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Enclosures:
As stated cc:
G. W. Reinmuth, IE D
. Tibbitts, NRR C. J. Heltemes, NRR
. T. Carlson, RI M. Kehnemuyi, SD
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February 24,1978 DN 50-352,,
.s 50-353.
MEMORANDJM FOR:
W.,J. Collins, Division of Reactor Operations Inspection, IE:HQ Il0 LOT I
FROM:
R.' C. Haynes Chief. Engineering Support Section No.1.
RC&ES Branch, 'll N 'n a C-
SUBJECT:
PIPE STORAGE. PRACTICES AT LIMERICK GENERATING STATION.,
UNITS 1 & 2
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REFERENCES:
(1) K. Kniel Ltr FECO, 7/14/77, same subject (2) Memorandum from R. Carlson.to K. Seyfrit 4/31/77 same subject.(AITS #12126H1)..
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(3) PEC01.tr to K..Kniel,11/4/77, same subject (4) Memo R. Carlson.to K. Seyfrit, 2/15/78,samesub[ect L
As agreed during our telephone conversation on February 23,.1978; regard-ing the above subject, the following is subnitted for your review and ccmmunication +.o NRR:
1.
Prompt resolution of this issue is needed so that Region I can determine:if the licensee is in compliance with. applicable regulatory requirements.
l 2.
NRR is encouraged to communicate to.the licensee those areas--
where additional assurance.'.is required befcre NRR-can conclude that the licensee's pipe storage practices are acceptable -i.e., the practices i
are coaducive to providing adequate confidence that the pipe will perform satisfactorily in service. Achieving this confidence requires the licensee to show that during the storage phase: (a) deleterious pipe corrosion is not exp(erienced; (b) harmful substances are not introduce into the pipe; anti c) unacceptable foreign material will not collect in the pipe which may not be removed during subsequent cleaning operations.
With respect to the corrod en concern, the licensee's response should l
address both general corrosion and localized internal pitting corrosion as you previously pointed out. A program of pipe wall thickness gaging using ultrasonics may be used to show that a pipe did not experience deleterious ganeral corrosion. However, as we discussed, this technique -
has limited usefulness with respect to pitting corrosion-since its.-
quantitative measurements of pit t'epth are unreliable. This was demon-strated during the torus wall inspections at Oyster Creek.
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l CONTACT:.J..P. Curr 1
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'488-1292 L
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j W. J. Collins, IE:HQ 2
Your continuing efforts to get this issue quickly resolved is appreciated.
Please advise Region I imediately if NRR determines that the licensee's present pipe storage practices do not fully meet regul-tory requirements so that we may initiate corrective enforcement actions.
__u Ronald C. Hayne,
ief Engineering Support Section No. 1 Reactor Construction and Engir.eering Support Branch cc:
F. A. Dreher, IE:HQ 6
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