ML010100519
| ML010100519 | |
| Person / Time | |
|---|---|
| Issue date: | 01/05/2001 |
| From: | Sheron B NRC/NRR/ADPT |
| To: | Modeen D Nuclear Energy Institute |
| Karwoski K | |
| References | |
| TAC MA4265 | |
| Download: ML010100519 (2) | |
Text
January 5, 2001 David J. Modeen, Director Engineering Nuclear Generation Division Nuclear Energy Institute 1776 I Street, NW Suite 400 Washington, DC 20006-3708
SUBJECT:
INTERIM GUIDANCE FOR IN-SITU PRESSURE TESTING PERTAINING TO PRESSURIZATION RATE
Dear Mr. Modeen:
By letter dated November 8, 2000, Interim Guidance for In Situ Pressure Testing (ADAMS Accession Number ML003770571), you provided the status of your evaluation of the Arkansas Nuclear One Unit 2 (ANO-2) steam generator tube pressure testing results which included interim guidance on the conduct of in-situ pressure tests. This guidance included specifying a maximum pressurization rate of 200 pounds per square inch (psi) per sec, adding additional hold points during the conduct of the test, and specifying a minimum hold time of two minutes to verify crack stability.
I understand the final report documenting your efforts will be published in 2001. Consistent with NRC comments at a public meeting on September 28, 2000, (see meeting summary dated October, 12, 2000, Summary of September 28, 2000, Meeting with the Nuclear Energy Institute (NEI) Regarding Steam Generator Tube Burst Integrity - ADAMS Accession Number ML003760794), the NRC staff will want to review the report before making any conclusions on this topic. In the interim, the modifications youve proposed to the in-situ pressure testing guidelines appear appropriate.
In your letter, you indicated the unexpected test results relate to any crack, greater than the through-wall critical crack length, that contains crack segments greater than 90% through-wall, but that the absence of the rate effect at very slow rates of pressurization has not been specifically demonstrated for other defect morphologies. Nonetheless, you concluded there was no dependency on pressurization rate in any of the industry standard correlation data sets.
Regarding these conclusions and observations, it would be beneficial if you further clarified their basis in your report in light of the fact that the absence of the pressurization effect has not been specifically demonstrated for other defect morphologies indicating to the NRC staff that the potential exists for the correlations to be affected.
At the September 28, 2000, meeting, the industry indicated it would consider doing some verification testing of their hypotheses regarding the necessary flaw morphology for observation of the pressurization effect. We would be interested in hearing the outcome of this activity.
David J. Modeen In summary, the NRC staff believes the NEI initiative is prudent given the results of the ANO-2 pressure tests and we appreciate your efforts on this matter. If you would like to discuss any of this information in more detail, please contact Jack Strosnider at (301) 415-3298.
Sincerely,
/ra/
Brian W. Sheron, Associate Director for Project Licensing and Technical Analysis Office of Nuclear Reactor Regulation cc:
Jim Riley, NEI Ralph Beedle, NEI
David J. Modeen In summary, the NRC staff believes the NEI initiative is prudent given the results of the ANO-2 pressure tests and we appreciate your efforts on this matter. If you would like to discuss any of this information in more detail, please contact Jack Strosnider at (301) 415-3298.
Sincerely, Brian W. Sheron, Associate Director for Project Licensing and Technical Analysis Office of Nuclear Reactor Regulation cc:
Jim Riley, NEI Ralph Beedle, NEI Distribution EMCB RF SCoffin RRothman AKeim EMurphy CBeardslee REnnis LLund ZFu JTsao JBirmingham SNewberry DOCUMENT NAME: C:\NEI letter on pressurizatio~.wpd INDICATE IN BOX: C=COPY W/O ATTACHMENT/ENCLOSURE, E=COPY W/ATT/ENCL, N=NO COPY OFFICE EMCB:DE E EMCB:DE E EMCB:DE NAME KKarwoski:kk E Sullivan:ejs W Bateman:whb DATE 12/ 22 /00 12/ 22 /00 12 / 22 /00 OFFICE DD:DE:NRR D:DE:NRR AD:ADPT:NRR NAME RHWessman:rhw JRStrosnider:jrs BWSheron:bws:
DATE 12/ 29 /00 1/02 /01 1/ 05 /01 OFFICIAL RECORD COPY