ML19290A371
| ML19290A371 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 07/01/1975 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19290A369 | List: |
| References | |
| NUDOCS 7911060610 | |
| Download: ML19290A371 (3) | |
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UNITED STATES NUCLEAR REGULATORY CCf. ".15SICN j
W ASHIN G TON, D.
C. 20055 SAFETY EVALUATION BY OFFICE CF NUCLEAR REACTOR REGULATIJN SUPPCRTING A"END"ENT NO. 6 TO LICENSE N0. DPR-3C Cl!ANCE NO. 6 TO TECI!NICAL SPECIFICATIONS
.METRGPOLITA?i EDIST: CC'C.WY TilREE !!ILE ISLAND NUCLEAR STiTION UNIT 1 DOCKET NO. 50-259 Introduction By letter dated "ay 14, 1975 and supplemented by letters dated June 9, 1975 and June 16, 1973, !!etronolitan Edison Coupany proposed an 1.:endm.ent t,
acilit-Operating License No. DPR-30 for Three !.lile Island Nuclear Staticr Unit 1.
The proposed amendment involves changes to the Technical Specifications.shich weut Revise certain requirements of the Tendon Surveillance Prograr relsted to a.
(1) frequency of inspection, (2) selection of tendons for inspectia., [3; conduct of the inspection, anu (4) procedures for reperting abnormal inspection results, Chanc.c the allowable deviatien for strain gage readir.:;s taken during b.
the Ring Girder Inspection Progran from +.004 in/in to ;.0004 in/in.
Require that deviations frcu allouable tolerances for Ring Girder c.
Inspection Tests be reported to the Station / Unit Superintendent rather than the Engineer.
Discussion Subsequent to the issuance of the Facility Operating License for Threc ;id e Island Nuclear Station Unit 1, the NRC staff revised Regulatory Guide 1.55,
" Inservice Inspection of Ungrouted Tendons in Prestressed Concrete Containment Structures". This revision resulted from positions developed througn discussions with the American Concrete Institute /American Society of >!cchanical Engineers Subgroup on Inservice Inspecticas of Concrete Pressure Components for Nuclear Service and reflects the current state of engineering incn ca;e with respect to tendon inspection rego.irements.
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By means of the proposed Technical Specifications changes, the licensee intends to ensure that its Tendon Surveillance Program is consistent with the provisions of Regulatory Guide 1.3S, Revision 1.
Evaluation Our evaluation of the proposed Technical Specifications changes is as follows:
A.
Changes associated with the Tendon Surveillance Program Requirements (1) The present Technical Specifications require that insarvice inspection testing of tendons be performed one, two, and three years after the Structural Integrity Test and every five years thereafter.
The proposal would change the frequency of inspection testing to one, three and five years after the Structural Integrity Test and every five years thereafter. The proposed change in frequency would provide a more uniform schedule for examination of tendon performance over the early stage of the unit'.s operational life; and, based on industry wide past experience, this examination schedule is as likely to reveal a failure in tendon performance as the previous examination schedule.
(2) The present Technical Specifications designate specific tendons for testing during each required Inspection.
The licansee has determined that some of the tendons presently designated for inspection are inaccessible to its testing equipment.
As a result, they have proposed the designation of different tendons for testing.
The proposed tendons have been selected on a random but representative basis so that the sample group will change somewhat for each inspection. This selection method reflects the current criteria accepted by the NRC staff as expressed in Regulatory-1.35, Revisien 1.
(3) The proposed change to the Technical Specifications includes
- a. provision which would permit a reduction of the number of tendons designated for inspection after the first three inspections by approximately one-half.
Such a reduction would occur only when supported by satisfactory operational experience with the tendons in the containment building as evidenced by the results of the first three inspections.
This proposal is based upon industry-wide experience with tendons in prestressed concrete buildings now reflected in Regulatory Guide 1.35, Revision 1.
This execrience and its use in preparing the proposed changes have accounted for the fact that corrosion effects on tendons are most likely to occur during the first five years of operation.
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(4) The proposed changes which are related to the conduct of the tendon inspections are minor in nature and involve:
acceptance criteria for grease samples, additions to the exampics of potential problen areas which should be checked during inspections, and nomenclature. The proposed changes reficct sound engineering judgement and practices.
(5) The proposed change which is related to procedures for reporting abnormal inspection results would require that tendon surveillance inspection test results be submitted to the U. S. ':uclear Regulatory Commission within 3 months of the completion of the tests rather then within 6 months as is currently reauired.
This is a more conservative plan for comunication of infur
- in (6) The proposed changes provide for a Tendon Sunqillance Program which is consistent with Regulatory Guide 1.n,
Revision 1.
B.
Changes Associated with Ring Girder Inspection Tests:
(1)
The proposed change associated eith the allowabic deviation for strain gage readings would correct an existing typographical error from +.004 in/in to +.0004 in/in.
Moreover, this
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proposal would provide a moIe conservative tolerance specification.
(2) The present Technical Specificatiens require that devictiens from allewable tolerances during "ing Cirder Inspectiv:. testing be reported to the plant Engineer.
The proposed chan; e sould designate the Station / Unit Superintendent as the individual responsible for evaluating and resolving unacceptable deviations rather than the plant Engineer.
This proposal would provide for attention to such discrepancies at a higher management level.
Summary Based upon our evaluation, we have concluded that the proposed Techr.a1 Specification changes are acceptable.
Conclusion We have concluded, based on the considerations discussed above. that:
(1) because the changes de not involve a significant increase in the probability or consequences of accidents previously considered and do not invoke a significant decrease in a safety margin, the changes do not involve a significant ha:ards consideratien, (2) there is reasonabic assurance that the health and safety of the public will not be endangered by operatien in the proposed manner, and (3) such activities will be conducted in cemlian e with the Ccmaission's regulations and the issuance of this amendment wil; not be ini:-ical to the common defense and security or to' the health and safety of the public.
Dated:
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