ML19289F308
| ML19289F308 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 04/25/1979 |
| From: | Jennifer Davis NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | Salava J WOLF CREEK NUCLEAR OPPOSITION, INC. |
| Shared Package | |
| ML19289F309 | List: |
| References | |
| NUDOCS 7906070212 | |
| Download: ML19289F308 (6) | |
Text
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j UNITED STATES e"
4 NUCLEAR REGULATORY COMMISSION j..
j WASHINGTON, D. C. 20555 e
f p
APR z 51979 Wolf Creek Nuclear Opposition Inc.
ATTN:
Mrs. John Salava Route 1, Box 56 Burlington, Kansas 66839
Dear Mrs. Salava:
The NRC has been conducting an investigation at the Wolf Creek fluclear plant of the facts and circumstances associated with the apparent low 90-day concrete strengths in the reactor containment building base mat.
This effort was initiated following the receipt of the final report from the licensee in late October of 1978.
The investigation has been under the direction of the Office of Inspection and Enforcement (IE) from the f;RC Region IV Office of Arlington, Texas and is broad in scope, addressing actions of the licensee as well as those of all pertinent contractors o'f the licensee. The preliminary findings indicate that the licensee's original commitments have not been satisfactorily demonstrated as having been met.
The matter of low concrete strength was initially reported by the licensee on March 15, 1978, shortly after the 90-day test results were known.
As a result of the indicated low strengths, the licensee perfomed its own investigations, including additional tests, to determine the cause of the measured low strengths for the concrete and to evaluate the in-situ strength of the reactor containment building base mat.
The licensee issued an interim report regarding it, investigations on May 25, 1978, and a final report on October 26, 1978.
During this time, the NRC Region IV Office maintained cognizance of the situation through its inspection program.
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Following receipt of the licensee's October 26, 1978 final report, IE initiated the NRC investigation discussed previously.
As a consequence of the NRC's preliminary findings, a technical meeting with the licensee was requested by the NRC's Office of Nuclear Reactor Regulation which reviewed and accepted the original commitments for concrete design and strength tests during the licensing review.
The meeting was held in Bethesda, Maryland on January 4,1979 and was attended by appropriate
!!RC staff and interested members of the public.
At that meeting the licensee described its actions and stated its position.
The NRC O'fice of Inspection and Enforcement presented comments and the preliminary findings on the matter.
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. APR 2 51979 A decision regarding the resolution of this problem has not been made as of this time and may require additional meetings with the licensee. The investigation report has been prepared as well as a report by an NRC consultant on this problem.
Additional information from new tests to be completed by the licensee will be considered in the final decision.
As yet there has been no direct evidence of faulty cement although it has been considered as a possible cause of low strength in the concrete by the NRC.
Numerous other possible causes have also been investigated.
As with all inspection or investigation reports, these are available in the Central Public Document Room at 1717 H Street, N.W.,
in Washington, D.C.
Copies are also available in the Local Public Document Room for the Wolf Creek, Unit I facility located at the Office of the County Clerk, Coffey County Courthouse, Burlington. Kansas.
The investigation report does not contain the resolution of this issue, but contains facts gathered by the Office of Inspection and Enforcement and the NRC con-sultant and the conclusions drawn from those facts.
Members of the interested public may obtain copies of the reports at either public document room.
Minutes of the meeting held on January 4,1979, are als'o available in the public document rooms.
The process of evaluating the findings was initiated with the meeting of January 4,1979, when the technical reviewers of the Office of Nuclear Reactor Regulation were informed of the results of the. licensee's studies as well as the findings of the NRC Office of Inspection and Enforcement.
We wish to point out that the original specifications relating to the acceptance of concrete based on test cylinders were not NRC requirements, but were provided to the licensee by Bechtel, the architect-engineer for the licensee.
These were based on the design criteria the licensee defined in the Safety Analysis Report which was reviewed and found acceptable by the Office of Nuclear Reactor Regulation.. All nuclear power plants do not necessarily have to meet this specification.
Some may, for example, use 3000 psi concrete at 28-days while others might require 6000 psi concrete at 90-days.
In the case of Wolf Creek, if the licensee is unable to demonstrate that the original specification can be met through the use of other tests or analyses, it is likely that a new structural evaluation of the reactor base mat will have to be performed.
This evaluation would ascertain whether the reactor containment building base mat can perform its intended function based on the actual as-built material strength properties indicated by the current test data.
Attempting to demonstrate acceptability may represent the most feasible method for the licensee since the reactor containment building at Wolf Creek is a SNUPPS plant design which is intended to have suffi-cient margins to be used at several sites in wide geographic locations.
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. APR 2 51979 This would indicate that for the Wolf Creek plant other margins are available which may tend to balance the degree of margin lost by the reduced concrete strength of the base mat.
Only detailed evaluations including analytical work can provide the basis for any such considera-tion of acceptability.
When deficiencies occur or when construction adequacy cannot be demonstrated, licensees may proceed with construction at their own risk.
However, any completed construction would not be considered justifica-tion for allowing safety margins to be reduced below what is considered necessary. The licensee will be required to demonstrate that the structural adequacy of the reactor building is acceptable under all loading conditions.
If major modifications, restoration or reconstruc-tion are required, the NRC will assure that those activities are success-fully accomplished prior to issuance of an operating license.
You may also be aware that several requests for halting construction or revoking the construction permit have been made by members of the public.
These requests are being appropriately addressed in accordance with NRC regulations.
Related correspondence will be available in the public document room.
We hope that this clarifies the current status of the resolution of this deficiency as well as providing you with an insight on what paths we see in the futu.re in assuring the plant's safety.
Your interest is appre-ciated and we will continue to respond to inquiries you may have as members of the public concerned about health and safety.
Sincerely,
/ry3
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fdohnG. Davis Acting Director Office of Inspection and Enforcement 2233'047
.. ApR % 51979 Distributi on:
L. V. Gossick, EDO J. G. Davis, IE H. R. Dentm, NRR J. P. Murray, ELD D. Th oro s on, I E K. V. Seyfrit, RIV G. W. Reinmuth, IE R. E. Snewmaker, IE E. Licitra, NRR IE Files Central Files /
PDR (50 482)/
LPDR (50-482) 2233 048 O
Summary of Concrete Problems Wolf Creek Nuclear Plant March 1979 Concrete wn placed for the reactor containment building base mat in a continuous operation on December 12 and 13, 1977.
The total volume of the 10 foot thick mat was nearly 6600 cubic yards.
Sample test cylinders of the concrete were taken during the placement and subsequently tested at 7 and 28 days after placement to determine the rate of strength gain.
Sample cylinders for the final 90-day strength determination also were obtained.
On March 13,1978, the 90-day cylinders were tested---about 95 failed to meet one test criterion; about 50!.; failed to meet a second test criterion.
The fiRC inspector was informed of the apparent low cylinder strength on fiarch 15, 1978.
Inspection Report STN 50-482/78-04, dated t' arch 31, 1978, noted that the question of the 90-day strength of the concrete for the reactor containment base mat had not been settled.
The licensee, Kansas Gas & Electric Company, informed the !!RC on May 3, 1978 that, in the licensee's opinion, the apparent low test results of the concrete strength were not required to be reported to the NRC.
The licensee agreed to send the !!RC for its information, a report about the licensee's investigations which had been initiated.
The NRC was pro-vided interim reports, dated l'ay 3,1978, "ay 25,1978 August 10, 1978, and September 29, 1978, about the progress of the licensee's investiga-tion.
The licensee's final report was submitted on October 26, 1978.
Review of the final report by the THlC raised questions about the conclusions contained in the report.
On November 13, 1978, the Region I'! (Dallas) Office of the NRC, with the assistance of a consultant, began an investigation into the apparent low strength concrete test cylinders.
By December 1,1978, the investigators had concluded from the information available that the specifications the licensee had established for acceptance of the concrete had not been met.and that the reactor containment base mat strength was in question.
The NRC pre-liminary evaluation of the base mat concrete strength based on the test cylinders indicated a value about 10!! below the intended strength of 5,000 pounds per square inch (psi).
On December 5,1978, a meeting was held by the Director of NRC Region IV with the licensee to discuss the status of the investigation and to emphasize the importance placed on this problem by the NRC.
On December 13, 1978, the licensee reporteo another concrete deficiency, a through-wall void in the concrete wall beneath the equipment hatch in the reactor containment building.
Another void was found beneath the personnel lock, but was not a through-wall void.
In a letter issued on 2233 049
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December 19, 1978, the NRC, through its Region IV Office, informed Kansas Gas & Electric Company of the NRC's concerns regarding the con-crete problems and the actions that the licensee was to address in order to satisfy these concerns.
The concerns related to the overall quality assurance program including controls and proct.dures related to concrete placement, quality control, inspection, testing and qualification of personnel, as well as the independence of the inspection and verifica-tica organizations.
The NRC also confirmed a commitment by the licensee to stop the placement of concrete in safety related structures until the quality assurance matters outlined in the letter were corrected and demonstrated to the satisfaction of the NRC.
On January 4,1979, a meeting was called by the NRC to discuss the findings of the NRC investigation and the position of the licensee on those findings.
The teeting, held in Bethesda, Maryland, included representatives of ali involved parties and members of the public and the news media.
As a result of the meeting, the licensee initiated additional testing on cube samples stated to ha.e been cut from the remains of the original 90-day test cylinders. The licensee submitted a report on February 28, 1979, describing the results of these additional tests.
That report is current 1' being evaluated.
The NRC in a letter dated February 8,1979, recuested that the licensee consider cut cube sample testing on remnants of 28-cay test cylinders and that an assessment of the concrete strength be made using the test data obtained from all of the test cylinders.
It was also requested that the value for the strength obtained be used to evaluate the load carrying capacity of the structure for the required loading conbinations. The licensee's response to these items has not yet been received.
Region IV, after additional inspections at the site during February 1979, concluded that the licensee had satisfactorily met the commitments agreed to in the December 19, 1978 letter. On March 5, 1979, another letter was issued by Region IV which called for no further placement of concrete in the reactor containment building until the question on the acceptability of the base mat has been resolved.
The licensee will, however, complete the necessary repairs to the voids in the reactor cor.tainment wall.
Tne licensee resumed placement of safety related concrete except for the reactor containment on March 6, 1979.
On March 8, 1979, the licensee stcope: work on safety related concrete after licensee quality control cersonnel observed that concrete was being moved by vibrat6rs over a create-horizcntal distance than oermitted by the governing code.
This ce#iciency was observed during tr.e placement of a wall section of the aaiiiary ouilding.
The initiative for the stop-work action was taken 2233 050
. by the licensee. The licensee lifted the stop-work order on March 22, 1979, relative to placement of safety-related concrete except for difficult placements and concrete in the reactor containment building.
Until results are received from the licensee relating to a structural evaluation using the actual test strength of the 90-day test cylinders, r.o final determination can be made on the acceptability of the base mat.
It should be noted that the need for 5000 psi strength concrete was determined by the licensee's architect-engineer and the value is not an NRC requirement. Typical base mat concrete strengths at other nuclear facilities have been specified at 3000 and 4000 psi at 28-days while others mignt require 6000 -psi at 90-days.
Needed concrete strength at a specific site must be consistent with the soil conditions and the specific structural loadings at each individual site.
There has been considerable public interest in this case resulting in several requests to the NRC for suspension or revocation of the permit to construct this plant. These requests still remain for final action.
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