ML20141N532
| ML20141N532 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 02/14/1986 |
| From: | Saffell B Battelle Memorial Institute, COLUMBUS LABORATORIES |
| To: | Liaw B Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML17058A523 | List: |
| References | |
| TAC-63425, NUDOCS 8603120207 | |
| Download: ML20141N532 (4) | |
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ENCLOSURE 3 OBaneHe Columbu> Dnmon 505 King Agenue Columbus. Ohu,41201-2#e# t Telephone iM4a 424 6424 Telen 24-5454 February 14, 1986 Dr. B. D. Liaw Chief. Engineering Branch Division of BWR Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Dr. Liaw:
Battelle staff and Dr. E. C. Rodabaugh attended a meeting on January 24, 1986 with NRC-NRR personnel (List of attendees provided in Attachment A) for the purpose of discussing the structural integrity of the Nine Mile Point Unit 2 downcomer design. This design is characterized by the lack of lateral support at the free ends of the downcomers.
l A submittal to the NRC by Niagara Mohawk Power Corporation, titled
" Review of Structural Adequacy of BWR Mark II Downtomers for the Nine Mile Point 2 Nuclear Power Station" provided the basis for this meeting.
For the purpose of our evaluation, the NRC staff provided the following guidance:
a.
No significant errors exist in the new calculati.ons documented in the submittal cited above b.
The 800 - series chugging loeds are applied by the Applicant in a manner acceptable to the staff From the review and evaluation performed at this meeting, we concluded the design meets licensing criteria for upset and emergency conditions.
We further concluded that the analysis review did not acceptably demonstrate compliance of the design with faulted conditions. While the downcomer design meets-the ASME Code faulted condition stress criteria, buckling of the downcomer during application of faulted condition loading is of concern and is discussed further in Attachment B.
In spite of this situation, we shared the consensus reached by this group that the NRC staff should continue to proceed with issuance of an operating license on the condition that by the first refueling outage c'ompliancebwith faulted condition criteria be demonstrated by the applicant and any required handware modifications be accomplished during the first refueling outage.
Our basis for this position is that:
[pS/Z$247 XR o
Dr. B.D. Liaw U.S. NRC 2
February 14, 1986
\\
l i
s l
a.
The main recirculation piping is 316 NG stainless steel which is considered much less susceptable to IGSCC than other steels; hence the probability of a major rupture of the primary piping is very low b.
The probability of the simultaneous occurrence of a LOCA and SSE is very unlikely during the life of the plant and even smaller during the first fuel cycle. Therefore, operation of the plant through the first fuel cycle poses no undue threat to the public health and safety Please don't hesitate to call me at FTS 976-5294 ff you wish to discuss this or require additional information.
Sincerely, f
's,./!
B. F. Saffell Program Manager -
Advanced Materials Department BFS/tj cc:
Y. C. Li E. C. Rodabaugh Attachments 4
1 i
O Attachment A List of Attendees R. Bernero (Part-time)
B. D. Liaw Y. C. Li C. P. Tan M. Hartzmann R. Wichman G. Larnas (Part-time)
E. C. Rodabaugh (E. C. Rodabaugh Associates)
G. M. Wilkowski (Batte11e's Columbus Division)-
B. F. Saffell (Battelle's Columbus Division)
R. Mesloh (Batte11e's Corporate Development Corooration) l l
l
Attachment B During the review meeting of January 24, 1986,. R. Mesloh of Battelle and Y. C. Li of the NRC staff compared estimates of bucking strength of the downcomers D/t = 64, at temperature.
For SA 312 (304 SS) the specified minimum yield, S = 22.75ksi 0 290' F.
Based on this y
value, it is understood that the NRC's calculations, following those of a paper by Belke, gave a buckling moment M = 5118 in-kips.
b Mr. Mesloh's estimation was based on extrapolating previously developed experimental data to suit the above yield value, strain hardening and expected strain at buckling. He estimates that buckling would I
occur at approximately 92% of the calculated maximum moment, 2
i Mm=DtSy = 4915 in-kips or at a moment j
Mb = 4520 in-kips.
]'
He further estimates a bending strain of cb = 0.6 to 0.7 %
and ovalization (flattening) of the pipe of F# 1.5 to 2 %
at buckling.
He cautions that these are estimated to " ball park" the anticipated buckling strength.
On this basis he concurs that the design is marginal-and that bucking is incipient at the estimated applied combined moment loadings (LOCA and SSE) of Ma = 4912 in-kips.
However, he also believes that the only " good" way of determining the actual buckling value is through experimental tests - either model or full scale with 304 stainless steel material exhibiting the same stress - strain characteristics as the downcomer material, and simulating the cantilever end condition.
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