ML19270G155
| ML19270G155 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 03/22/1979 |
| From: | Koester G KANSAS GAS & ELECTRIC CO. |
| To: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| Shared Package | |
| ML19270G150 | List: |
| References | |
| NUDOCS 7906050064 | |
| Download: ML19270G155 (6) | |
Text
.
KANSAS GAS AND ELECTRIC COMPANY s
GLENN L. MOE$ f E 9 vtC E ppE taDtht Opg natio%s March 22, 1979 Mr. Karl V. Seyfrit Director, Region IV Office of Inspection & Enforcement U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76012 Re: STN 50-482/Rpt. 78-13
Dear Mr. Seyfrit:
This letter is written in response to your letter of February 16, 1979, which transmitted Inspection Report 50-482/78-13. As requested, each finding is being addressed in three parts:
a)
Corrective steps which have seen taken and the results
- achieved, b)
Corrective steps which will be taken to avoid further non-compliance, and c)
The dates when full compliance will be achieved.
1.
Finding Failure to Establish Mix Design 42-C-1A-M (Rev 1) According to Specifications and Procedures.
Method 1 of ACI 301, paragraph 3.8 was not followed when establishing the mix proportions of Mix Design 42-C-1A-N (Rev 1).
The required average strength (target strength) for Design Mix 42-C-1A-N (Rev 1) was not established in accordance with Section 3.8.2.3 of ACI 301.
Response
a)
A review of available information shows that Method 1 of ACI 301 was not strictly followed in establishing the mix design designated 42-C-1A-N Rev 11 The failure to properly qualify the earlier revisions of this mix was identified during a Daniel audit conducted June 12-15, 1978.
7906050Cfol C
Mr. Karl V. Seyfrit March 22, 1979 Analysis of al) concrete 90-day test results for mix design 42-C-1A-N (Rev 1) for concrete batched prior to and subsequent to the base mat shows that the mix is capable of producing strengths in excess of that required for the base mat.
This analysis is based on ACI 214 guidance and uses the Code Committee recommendation of.10 for the probability of any test falling below the design strength (fc').
Equation #7 from ACI 214 fcr = fc' (1-tV) fer = required average strength fe' = design strength specified t
= constant depending upon proportion of tests that may fall below fc' and the number of samples used to establish V V
= coefficient of variation expressed as a fraction For 42-C-1A-N concrete placed prior to the base mat:
8.4%
V
=
1.282 from ACI Table 4 with more than t
=
30 samples fcr = 5000
= 5603 1-(1.282 x.084)
The actual average strength experienced was 6003.
For 42-C-1A-N concrete placed after the base mat:
5.6%
V
=
1.282 from ACI Table 4 with more than t
=
30 samples fcr = 5000
= 5387 1-(1.282 x.056)
The actual average strength experienced was 6391.
b)
The project Civil Engineer has been directed to strictly follow ACI 301 Method 1 for all new mix designs. Also, procedure WP-IV-103 will be revised to require that complete documentation for all new mix designs and adjustments to mix designs will be sent to Daniel's corporate headquarters for review and approval by Technical Services personnel prior to use at Wolf Creek.
c)
Actions indicated above are complete except for revising procedure WP-IV-103, which will be revised and issued by April 15, 1979.
Mr. Karl V. Seyfrit March 22, 1979 2.
Finding Failure to Meet Cor. crete Acceptance Critaria for Containment Base Mat.
The strength level of the base mat concrete is not considered satisfactory, in that, the averages of all sets of three con-secutive strength test results failed to equal fc' for thirty of the sets of cylinders. Also, the individual strength test results for six cylinder tests fell more than 500 psi below fc'.
Response
a)
The low values for the ninety (90) day base mat test cylinders were recognized and processed on Nonconformance Report No. 1-0229-C which was originally issued on March 14, 1978, the day af ter the anomaly was discovered. On March 15, 1978, the NRC was notified of the event by verbal communication to the I&E Inspector who was on site that day.
The acceptance criteria for the base mat concrete is based on cylinder test results; however, after the cylinders were destructively tested, it became necessary to utilize alternate methods to further evaluate in-situ strength. The size of the base mat and the density of reinforcing steel make some alternate methods such as load testing or coring impractical or impossible to perform. However, other methods of evaluating concrete strength could be performed. A program of analysis and testing was developed to yield reliable strength data and to provide the best opportunity of determining why the 90-day cylinders tested lower than expected.
Results of completed tests and evaluations have been forwarded to you.
Additional testing is being performed and the results will also be forwarded. To date the alternate testing has failed to confirm low strength.
The alternate testing and evaluations so far completed indicate the concrete was properly batched and mixed, that no adverse chemical reaction has occurred and that the true strength of the concrete cylinders, as determined by measuring the compressive strength of cubes cut from cylinder remnants, is sufficient to meet the ACI 318 acceptance criteria.
b)
The exa$t cause of low 90-day cylinder strengths has not yet been determined but the most probable causes are related to the moulding, handling, capping and testing of the cylinders.
If the exact cause of the problem is identified, other measures may be necessary; but, for now the following measures to prevent reoccurence have been initiated: Laboratory personnel
Mr. Karl V. Seyfrit March 22, 1979 have been instructed to retain all fragments from cylinders which fail below the design strength and to notify top management immediately when test failures occur, and the compression testing machine is being replaced with a new high quality machine with twice the capacity of the old machine.
c)
Compliance for this item will be considered complete when the NRC is assured of the adequacy of the base inat.
3.
Finding Failure to Provide Complete Information in NCR l-0229-C.
Nonconformance Report (NCR) No. 1-0229-C, dated April 14, 1978, which was submitted to Bechtel, the proper authority for resolving NCRs, was not complete in that sixteen additional cylinders, which did not meet acceptance criteria of ACI 318, should have been included.
Response
a)
Although not attached to the final copy of NCR l-0229-C, complete information on all 7, 28 and 90 day base mat cylinders was provided to our A/E by September 29, 1978, prior to their evaluation and returning the NCR on October 24, 1978. Jomplete sets of compressive test reports for the base mat cylinders have been sent to the NRC and are on site in the record vault at Wolf Creek.
b)
The Daniel Construction Engineering Manager has been directed to check all NCRs for accuracy and completeness to the extent permitted by available information prior to approving them and transmitting them to the appropriate A/E. Also, supple-r~*.al information submitted to the A/E shall either be attached to or referenced on the final record copy of the NCR.
c)
Full compliance for this item was achieved on March 5, 1979.
4.
Finding Failure to Complete User Tests Within Time Limits.
Ten User Tests (No. 9-13, 15, 17-20) exceeded the maximum time limit of 33 days by 1 to 23 days.
Mr. Karl V. Seyfrit March 22, 1979
Response
a)
Our Constructor (DANIEL) interpreted ASTM C-150, paragraph 9, to mean that the agent performing the user test should be allowed the minimum length of time indicated in paragraph 9.
The responsible A/E has concurred in this interpretation of the ASTM C-150 requirement. Thus it appears no violation has occurred.
b)
No corrective action appears to be necessary.
c)
Full compliance for this item has been achieved.
5.
Finding Failure To Conduct 3-Day Cement Compression Tests.
Three-day compression tests were not conducted for User Tests No.10 through 19.
Response
a)
Bechtel Specification 10466-C101, Item 11.2, states in part, " Ordinarily, no cement shall be used until it has satisfactorily passed the 7 and 28 day tests. Strength requirements at 28 days shall satisfy the requirements of ASTM C-150 Table 2a."
Our Constructor interpreted this to mean 7 and 28 day tests were required instead of 3, 7 and 28 day tests. An inquiry to the responsible A/E has provided the interpretation that the three-day test should be performed. A Nonconformance Report will be processed for cement used to date which lacks the three-day test.
b)
Quality control laboratory personnel have been instructed to perform the three-day test for cement strength, c)
Full compliance for this item will be accomplished when resolution and close-out of the above NCR is complete (now estimated to be May 7,1979).
6.
Finding Failure to Follow Specification in Regard to Statistical Analysis of Concrete Cylinder Tests.
Ninety-day base mat test cylinders, which were cast on December 12, 1977 and were tested on March 13, 1978 (91 days later), were used in the computation of the coefficient of variation.
Mr. Karl V. Seyfrit March 22, 1979
Response
f a)
A review of the data shows that a coefficient of variation was calculated using both 90 and 91 day data. The A/E has affirmed that the intent of this specification provision is to have the best possible data to use for mix design adjust-ments. As this calculation was not used to adjust the mix, no adverse effect has resulted.
b)
To assure that this does not become a Noncompliance, the Project Civil Engineer has been instructed to use only cylinders tested on the specified day for all situations where the computation is to be used for adjusting the mix.
c)
Full compliance for this item has been achieved.
Your letter of February 16 also requested that we identify the specific steps that have been or will be taken to correct the apparent weakness in our management controls and in our Quality Assurance Program.
We have retained an independent consultant with a strong background in nuclear-related activities to review our QA Program as carried out by KG&E and our Constructor. His scope of work includes ~ a review of the KG&E and Daniel organizational structures, the training and experience level of Senior Project personnel and the quantity of assigned personnel. When the final report of his work is available (expected in May), it will be reviewed by KG&E Management and to the extent practical, his recommendations will be followed and measures will be *aken to resolve identified problems.
Also, we have increased the on-site (;A Staff to five employees by contracting for two additional experienced indiriduals from nuclear service organizations.
We are actively recruiting permanent QA Engineers; however, we will retain our contract personnel until permanent employees can be hired and trained.
Please advise if you have further questions or comments.
Yours very truly,
'm v GLK:bb