ML20038C467
| ML20038C467 | |
| Person / Time | |
|---|---|
| Site: | Marble Hill |
| Issue date: | 09/10/1981 |
| From: | Remick F NRC |
| To: | Bradford P, Gilinsky V, Palladino N NRC COMMISSION (OCM) |
| Shared Package | |
| ML20038C466 | List: |
| References | |
| DD-81-10, NUDOCS 8112110090 | |
| Download: ML20038C467 (4) | |
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ENCLOSURE 1
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- UNITED STATES
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NUCLEAR REGULATORY COMMISSION g
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September 10, 1981 MEMORANDlM FOR:
Chairman Palladino Commissioner Gilinsky Commissioner Bradford Commissioner Ahearne Commissioner Roberts FROM:
Forrest J. Remic
SUBJECT:
REVIEW OF DIRECTOR'S DENIAL OF 2.206' PETITION (SECY-81-445)
As requested by Commissioner Bradford in his memorandum of August 21, OPE has reviewed Professor Cassaro's September 26, 1980 and March 4, 1981 comments and the staff's response.
Based on the following comments, we recommend that, before reaching a decision on your review of the Director's denial, the matter be referred to the staff for further study
'of certain questions we have identified concerning the test' and evaluation program for assuring that the concrete placement at Marble Hill meets NRC requirements.
Statistical Methodology for Sampling Professor Cassaro is correct in his mathematical argument that the assurance inherent in Sargent and Lundy's (S&L) acceptance sampling plan, which formed the'statisticd basis for testing the quality of concrete in structures at Marble Hill, is not compatible with the "95 percent confidence
[of] 95 percent reliability" criterion (denoted henceforth as 95/95 assurance criterion; this is equivalent to having 95 percent confidence that no more than 5 percent of the concrete areas"are defective) that the staff specified on June 27, 1979 (Enclosure 1). Apparently, S&L mistakenly applied calculations suitable only for single-stage sampling (see S&L's procedure and stated reference (Ang and Tang) on page 5 of Volume I of the S&L report).
To satisfy NRC's criterion, sample sizes for each of the four stages in the sampling plan should have been larger-
--perhaps by as much as 10 or 20 t'est areas per stage, depending on the l
exact scheme chosen.
l As verified independently by MPA calculations, S&L's sequential sampling plan (pages 5-8 of Volume I, SL-3753, Revision 1, November 21,1980),
which would have allowed as many as 3 defectives, could provide only about 90 percent confidence of 95 percent reliability.
In comparison l
CONTACTS:
Cookie Ong, OPE 63-43302 8112110090 811023 PDR ADOCK 05000546 A
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Commission with single-stage plans, a multiple-stage sampling approach requires a potentially larger total sample size.
However, since actual observations may lead to early termination of the plan, sequential sampling plans on an average result in smaller numbers of observations than comparable single-stage plans.
It is important to note that had a single-stage plan-instead been implemented, the observed results (no defectives in 60 tests) would have provided 95/95 assurance. Moreover, we note that "a substantial amount of' engineering judgment was used to conservatively bias' the sample selection." S&L took a stratified random sample with observations weighted heavily to strata with a higher potential for failure, where half of the 60 observations were drawn as representative of areas which are congested by reinforcing steel and the embedment arrangement, and which have greater potential for discontinu.ities.
Hence, if an appropriate 4+ stage sample had been
- u. sed, 95 percent reliability could have been assured w'ith a confidence actually greater than 95 percent--particularly in view of measurement replication and follow-up measurements.
In any case, NRC made no apparent specific allowance for test error on top of sampling error when it set the 95/95 criteria.
Accounting for Huma'n and Instrument Error A principal concern of Professor Cassaro was that NRC's 95/95 criterion could not have been satisfied by S&L's methodology because their calculations did not include the effects of residual human error and instrument error in the test program. Note that in Professor Cassaro's letter of March 26, 1981 (Enclosure 2) he stated, "It appears that no written qualification exists in the record at Marble Hill."
The staff's response of March 20, 1981 along this line appears to accurately reflect the microseismic testing program described in S&L's report--
particularly in regard to how to identify, categorize and evaluate the test areas as being solid, explainable or questionable. Procedures included specific steps to detect the presence, if, any, of unacceptable discontinuities in the 60 areas tested (i.e., applying pulse-echo testing; review of drawings and construction records for correlation with pulse-echo test data; and follow-up coring, as needed). The staff's letter of July 22, 1981 (Enclosure 3), furthermore, elaborated substantially on S&L's measurement technique and evaluation methodology--including the fact that a qualification test and record for the microseismic testing technique does exist at Marble Hill, as documented by an NRC inspection report. Qualification tests are also documented in the S&L report.
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Commission
-32 Accordingly, a substantial effort was made to minimize human and instrument error.
Professor Cassaro's reservations could have been justified only if the probability of misclassification (in this case, failure to recognize a defective area as such) was not negligible.
(For a non-negligible test error, which is apparently not the case, the probability of misclassification would have otherwise been, in Professor Cassaro's words, " conjoined with the probability of finding defective concrete in the S&L plan."
Finally, we understand that, with regard to another of Dr. Cassaro's concerns, a copy of the final report of.the NRC consultants, Hamm and Parme, dated June 25, 1981, was received by IE in time for consideration in the Director's Denial on June 26, 1981.
Ham and Parme supported the S&L report conclusions.
(Enclosure 4 is a copy of the consultant's final report, which was forwarded to Public Service of Indiana on July 1,1981.)
Possible Next Steps The staff's conclusion in its letter of' March 20, 1981 to Professor Cassaro, "that the required reliability and confidence can be demonstrated by the methodology described in the S&L revised report," is not fully supportable, since S&L's statistical methodology for selecting the number of random samples in a stepwise approach was incorrect.
S&L's sequential sampling plan could provide only about 90/95 assurance.
We considered whether S&L should be required to correct its documented sampling plan.and draw corresponding. additional samples. Arguing against such a' step is the fact that NRC staff did approve the 4-stage S&L sampling plan and, with that approval, it in effect (unwittingly) changed the assurance criterion to 90/95.
In any event, the sample appeared to be appropriately collected and treated and no significant defects were found. Therefore, in spite of an apparent shortcoming in S&L's 4-stage sampling plan methodology, NRC's best estimate today--based on available information and in the context of a 1-stage sampling plan--is that there is 95 percent assurance that no more than 5 percent of in-place concrete units are defective (or, in the staff's terminology, 95 percent confidence of 95 percent reliability).
Thus, although S&L apparently made a mistake in its sampling plan, it.is not clear to us that that mistake is significant enough to justify altering the Director's Denial. The Cormission itself could decide, for example, that results from the S&L sample nevertheless provide, as discussed.
above, sufficient confidence and reliability on the basis (retrospectively) of a single-stage sampling approach.
However, it could be that we have not identified all relevant factors, and it seems to us better to let the staff attempt to deal with and clarify the matter before the Commission takes a position.
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Commission
-45 Recommendation 0GC believes it is arguable whether the cited problem with the decision requires Commission review under the usual Indian Point standard in light of the indication above that the difficulty is not significant.
However, the Commission, if it chooses, could pursue this matter in exercising its supervisory authority over staff.
See 10 CFR 2.206 (c) (1).
On balance, we recommend that you exercise this supervisory authority and j
(1) hold up your decision on the Director's Denial; and (2) refer to staff for examination with all parties, in light of STV's July Addendum, the confidence level achievable by S&L's^ documented sampling plan.
Enclosures:
As stated cc:
Samuel Chilk William Dircks Victor Stello Harold Denton Harold Bassett l
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IN RESPONSE REFER TO S81-445 h ttcy j
UNITED STATES qs o#^
NUCLEAR REGULATORY COMMISSION ENCLOSl'RE 2 F'
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WASHIN GTON, D.C. 20SS5 SN
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OFFICE OF THE SECRETARY -
MEMORANDUM FOR:
William J.
Dircks, Executive Directorf for Operations I
FRO.M:
Samuel J.
Chilk, Secreta. -
SUSJECT:
~SECY-81-445 - REVIEW OF DIRECTOR'S
, DENIAL OF 2.206 PETITIOlsD This is to advise you that the Commission (with all Commissioners approving) has decided that the staff should examine with all parties-whether the assurance achievable from the test and evaluation program.at Marble Hill meets NRC criteria in light of Save the Valley's July. Addendum and OPE's memorandum of September 10, 1981.
The Office of the Director, Inspection and Enforcement was informed of this action by telephone on October 1, 1981.
It is requested that you respond to-this request by c.o.b. November 13, 1981.
cc:
' Chairman Palladino Commissioner Gilinsky Commissioner Bradford Commissioner Ahearne Commissioner Roberts OGC OPE Director, I&E Chief, Docketing & Service Branch, SECY CONTACT:
E.
W.
McGregor (SECY) 41410 1
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ENCLOSURE 3 g,
b $55Y5 BEFORE THE I.*UCLEAR REGULATORY CO!I!!ISSION gg/jj 3n
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'1ASHINGTO!I, D. C.
I/D 3to IB&PI b i
v COMMIGSIONERS, Joseph M.
Hendrie, Chairman tNzt.71 M s
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- Peter A.
Bradford Victor Gilinsky NEM N'
John F. Aherne IN THE MATTER OF PUBLIC SERVICEi COMPANY.OF INDIANA, MARELE MILL NUCLEAR POWER PLANT, DOCKET NOS.
STN 50-546 AND STN'50-547 SAVE THE VALLEY'S ADDENDUM ~TO ITS APRIL 14 1981 PETITION TO THE COIO!ISSIONERS TO REVIE*** TIiE NUCLEAR REGULATORY COMMISSI_ON ifARCH 27 1981 ORDER TO RESUME CONSTRUCTION AT MARBLE HILL Comes now Save The Valley (STV), by its attorney, and for cause of Addendu.m to the above Motion, s ta:;es:
1.
That on or about June 26, 1981 Victor Stello, Jr., D'irec tor of Inspection & Enforcement, flied nis decision under 10 CFR 2.206 substantially accepting that the Marble Mill concrete in the aggregate does :,1ee t.luelear Regulatory Commission ( t!RC ) structural integrity cri:eria of 95% relianility and 95% confidence.
l 2.
That on or about June 25, 1981, there was prepared by Alfred L. Par =e, Consuining Engineer, La Jolla,' California, and Roland C.
- Hamme, P.E.,
San Diego. California, a certain Review of the Evaluation of Concrete at i.iarble Hill Muelear Generating Station, Units 1 & 2, Report #IE-124, which Report substantially concluded that the Marbie i
Ilill concrege meets the NRC requirements of 95% reliability and 955 confidence level.
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That said Alfred L. Parme and Roland C. Hamme did not include in their evaluation consideration of the effect of the-slightest possible human error in the de termination of R. Muneow;..
further, it is stated on page 13 of the report. "As a result of '
discussions with R. Muneow And others who are reputable,, experienced e
and preisently involved !1n the field of microseismic testing, we' have.
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concluded that the me thod of non-destructive testing perfor=ed. at Marble Hill is acceptible.
The interpretations made and: equipment
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used by R. Muneow are at the forefront of the state of the art "
4.
Again,. Doctor Muneow's qualifications are not questioned;'
however, the particular, task that he performed is an art and not a science and, therefore, cannot be given a qualification rating or
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100%.
Taking a qualification rating of 99% and placing said value on R. Muneow, the statistical basis for the ?!RC conclusion of 95%
confidence with 95% reliability falls apart.
S.
STV has presented a written critique of the section
" Statistical Basis for Testing Program" by Suraj M. Alexander',
Ph.D.,
P.E., Asst. Professor of Engineering Management / Industrial 2ngineering, Speed Scientific School, University of L,ouisv111e, addressing this statistical determination and concluding without question that the NRC determination is inaccurate, incorrect and even unintellidible; that Prbfessor Alexander is highly qualified in the area of quality control with an in-depth background in statistics, 2.
e WitEREFORE, Save The Valley respectfully requests the Commissioners prior to the time that, the 10 CFR 2.205 decision of Victor Stallo,. Jr.,
becomes the final action of the agency to institute a review of said !
June 26, 1981 decision, to order the independent engineers to be prepared to testify before the Commissi,on.in Washington...D.C.,
' to defend their statistical determination of 95% confidence and 95%
reliability; the Commission is further ~ requested to order Save The -
Valley to present its witnesses personally before said Commjssiont to defend its conclusion that said 95% confidence and 95% reliability.has not been demonstrated by the NRC concerning the Marble Hill concre,te.:
RESPECTFULLY SUBMITTED, SAVE THE VALLEY, PETITIOtIER BY;
- 8. p.s *
- a T,. 4 <.:1 (N.
7.E THOMAS M.
DATTILO,. ATTORNEY FOR PETITIONER 311 EAST MAIN STREET MADIS0tl, INDIANA 47250 l
PHONE: 812-265-6355 DATED:
JULY 10, 1981.
3.
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s CERTIFTCATE OF SERVICE I hereby certify that a copy of the foregoing Addendum has been mailed to the following persons by regular U.S. mail, postage prepaid, this 10th day :of July, 1981:
Peter A. Bradford, NRC, Washington, D.C.
20555 Joseph M.
Hendria, NRC, Washington, D' C.
20555 Victor Gilinsky, NRC,. Washington, D.C.
20555 John F. Aherne, NRC, Washington, D.C.
20555 James Keppler, NRC, Roosevelt.Rd., Glen Ellyn. Ill.
James Pope, Public Servic= Company of Indiana, 1000 E. Main St.,
Plainfield, Indiana 46168 HRC Docke ting Section, Washington, D.C.
20555 5
Y Th0 MAS :.l.
DATTILO
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