ML20039C180
| ML20039C180 | |
| Person / Time | |
|---|---|
| Site: | Marble Hill |
| Issue date: | 11/30/1981 |
| From: | Deyoung R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| Shared Package | |
| ML20039C179 | List: |
| References | |
| DD-81-10, DD-81-22, NUDOCS 8112280549 | |
| Download: ML20039C180 (7) | |
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S DD-81-22 UNITED' STATES l
NUCLEAR REGULATORY COMMISSION OFFICE OF. INSPECTION AND ENFORCEMENT Richard C. DeYoung, Director In the Matter of
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PUBLIC SERVICE COMPANY
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Docket'Nos. STN 50-546~
OF INDIANA
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STN 50-547 (Marble Hill Nuclear
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Generating Station, Units 1 & 2)
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SUPPLEMENTAL DECISION UNDER 10 CFR 2.206 On June 26, 1981, a decision was issued under'10 CFR 2.206 (DD-81-10,13 NRC
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that denied a-petition filed by.Save the Valley which requested withdrawal of the authorization to Public Service Company of Indiana (PSI) to resume concrete work on the Marble Hill. project.
After considering the bases for Save the Valley's request and other information related to the examination of the quality
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of concrete in the project as well as the' improvements made in PSI's construction program, Save the Valley's petition was denied.
As part of the Commission's review of the decision, the Office of Policy Evaluation (OPE) was asked to review the comments of-Dr. Michael Cassaro,-a consultant to Save the Valley, regarding the statistical model which Sargent and Lundy had used in establishing-a sampling plan for testing the quality of concrete in structures at the. Marble Hill project.
Dr..Cassaro stated that the sampling plan contained an error which had not been identified by the staff.
In its review, OPE confirmed that the' sequential sampling plan devised by Sargent and Lundy was in fact in. error.
The staff concurs in OPE's analysis of Sargent and Lundy's sequential sampling plan.
However, in effect a far more stringent sampling plan was implemented, i
' with the result that the test findings (over 1400 readings in 60 areas'with no observed defects) more than achieved the stated criterion.
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. OPE has therefore, determined that the results of the testing program performed achieved the desired assurance (95% assurance of 95% reliability) that the concrete quality meets NRC requirements.
Because the Sargent and Lundy sequ'ential sampling plan could have affected the staff's conclusions regarding the quality of the concrete, the Commission asked "whether the assurance achievable from the test and evaluation program at Marble Hill meets NRC criteria in light of Save the Velley's July Addendum [to its petition] and OPE's memorandum of September 10, 1981".1 This supplemental decision reflects the results of the staff's review in response to the Commission's request.
In conducting this review, the Staff has also considered, in addition to the two documents mentioned above, a letter dated August 5, 1981, from Save the Valley's counsel to the Commission.
In -
response to the Commission's request, copies-of the OPE evaluation and the Commission decision were transmitted to Save the Valley, and to PSI,. soliciting their comment.
PSI responded by letter dated November 2, 1981.
Save the Valley provided a response dated November 4, 1981.
The content of these submissions has been considered in developing this supple-mental. decision.
The conclusion is that had a single-stage sampling plan been implemented, the observed results would have provided the required 95% assurance
.of 95% reliability.
Therefore, for the reasons stated in this supplemental IMemorandum for W. J. Dircks, Executive Director for Operations, from S. J.
Chilk, Secretary, (Oct. 5,1981).
A copy of this memorandum and all other documents referred to in this decision are available for public inspection in the Commission's public document room in Washington, D.C., and the local public document' room in Madison, Indiana.
- decision, additional concrete sampling is not necessary or warranted to 'ssure a
acceptable confidence in the quality of concrete in the Marble Hill structures.
Sargent and Lundy developed the te. sting program for PSI.
PSI had committed to p vide assurance through statistical sampling that the concrete's quality was acceptable.
Region III had confirmed PSI's commitment in an Immediate Action Letter dated June 27, 1979.
The Immediate Action Letter did not specify a particular sampling method or program, but asked that the testing demonstrate l
adequate cuality of the concrete by achieving 95% assurance of 95% reliability.
As stated above, the sample tested has verified that the concrete quality does achieve the stated goal.
The test results more than achieved the stated criterion.
The Sargent and Lundy L
sequential sampling plan required a first stage of 59 statistically independent readings, a second stage (if necessary) of 34 additional readings, etc.
As the plan was implemented 60 sample areas were tested at several overlapping locations i
for a total of over 1,400 separate microseismic tests for the 60 areas.
Even though not all these may be statistically independent readings, there were clearly far more than the equivalent of 60 independent readings.
Hence, with no observed defects, the acceptance criteria of 95% assurance of 95% reliability has been far exceeded.
In Save the Valley's July Addendum and its August letter to the Commission, Save the Valley argues that Sargent and Lundy's testing program is unable to
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achieve the required confidence level because the effects of instrument error l
. 4 and human error are not included in the test program.
Region III has previously responded to this concern in letters dated March 20 and July 22, 1981, to Dr. 'Cassaro, Save the Valley's consultant.2 The measurement techniques and methodology for performance of the microseismic testing provided adequate
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safeguards against human or instrument error to the extent that, if errors were present, they would have had negligible affects on the test results.
Each of the test locations within the 60 areas was usually tested at least twice before they were accepted for record.
Each test that indicated a reflector was independently analyzed to determine whether the reflector could be attributed to a planned as-built condition:
e.g., to the presence of rebar, conduits, or pipe sleeves which would be detected as discontinuities in the concrete by the microseismic testing technique.
If available data and drawings were inconclusive, the area was tested destructively, by coring or line drilling, for evaluation.
Cores were also taken from at least four areas which had been reported to be homogeneous concrete.
Three different organizations participated 1
in the evaluations with separate responsibilities.to minimize error during acquisition and evaluation of data.
Equipment performance tests were conducted at the beginning and end of each testing day.
Qualification tests for the 3
program are documented in tha Sargent and Lundy report and in NRC Inspection Report No. 50-546/79-07--5J-547/79-07 dated September 18, 1979.
An NRC inspector observed qualification of the testing procedure prior to its implementation..
Moreover, 21 additional destructive tests (cores and/or line drilling) were
- See Attachment A, T3, of letter from J. G. Keppler to Dr. M. A. Cassaro-(March 20, 1981); Attachment A, SC1 & 3, of letter from J. G. Keppler to Dr. M. A. Cassaro (July 22,1981).
3 Report SL-3753 Rev.1, dated November 21, 1980.
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i 7 performed at the request of the NRC's independent consultants.
These additional tests did not identify any errors in the results that the previous microseismic testing had established.
The NRC consultants also requested a test of the transducer (the equipment used in the microseismic testing).
The test was performed on a one foot cube of concrete on February 9, 1981. -After the instrument indicated a discontinuity in the concrete cube, the cube was sawed and the discontinuity was found.
Dr. Cassaro as well as the NRC's independent consultants witnessed this test.
Since adequately conservative procedural safeguards were implemented to preclude instrument and human error during the microseismic testing, errors that could be present would have had a negligible affect on the testing results.
In view of the foregoing information.regarding the results of the-tests that
. were actually performed, additional testing of the concrete quality is not necessary.
The 60 areas that were tested were appropriately selected to include a large number of potentially defective areas, and the tests were performed in an appropriate manner.
The NRC's independent consultants reviewed the test results and had additional destructive tests performed to confirm the results found in the Sargent and Lundy program.
The consultants found as a result of their investigation that the concrete quality was ' acceptable at Marble Hill.4 Other efforts to evaluate concrete quality have included rigorous examination of exposed concrete surfaces c d repair of any defects.
Special constraints were imposed on continued construction work to ensure that surface areas were examined and repaired before they were covered by additional
- See Parme & Hamm, Review of-the Evaluation of Concrete at Marble Hill Nuclear Generating Station Units 1 and 2, Report No. IE-124 (June 25,1981).
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.- construction work.
Upon consideration of the results of the testing that has been conducted, additional testing is not required.
On the basis of available information, the concrete quality does provide the required assurance of 95%
assu'rance of 95% reliability.
Based on the results of the described program, and information known to the staff, no further action is warranted at this time to assure that the Marble Hill structures contain concrete'of acceptable quality.
In its July Addendum and its August letter to the Commission, Save the Valley asked that a hearing be held before the Commission concerning the acceptability of Marble Hill's concrete.
The Commission is not required to hold a hearing to determine whether it should review a decision under 10 CFR 2.206 cr should grant a section 2.206 petition.5 The holding of hearings on a section 2.206 petition would be an extraordinary action and is not warranted in this case. -
The Commission has before it a substantial amount of information concerning the quality of Marble Hill's concrete.
Save the Valley's views have been presented in it filings before the Commission and the technical analyses prepared by its consultants, Dr. Cassaro and Dr. Alexander.
The licensee _has submitted its comments on the OPE memorandum. The NRC Staff's views are set forth in this decision and in DD-81-10, and in its correspondence with Dr. Cassaro.
The 4
Commission also has the benefit of OPE's analysis and the report of the NRC's i
L independent consultants.
These various documents form a comprehensive basis i
? People of the Statt of Illinois v. NRC, 591 F.2d 12 (7th Cir. 1979).
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O from which the Commission can judge whether to review my determination not to require further concrete testing and my decision not to withdraw the authoriza-tion for PSI to resume construction.
In light of these circumstances, I do not recommend that the Commission hold the requested hearing.
W eoung,h4 rector Richard C.
Office of n pection and Enforcement Dated at Bethesda, Maryland, this 3 day of November 1981.
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