ML19275A880
| ML19275A880 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 10/09/1979 |
| From: | Case E Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19275A881 | List: |
| References | |
| NUDOCS 7910220134 | |
| Download: ML19275A880 (8) | |
Text
i UNITED STATES OF AFERICA NUCLEAR REGULATORY COMPISSION OFFICE OF NUCLEAR REACTOR REGULATION HAROLD R. DENTON, DIRECTOR In the Matter of
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PHILADELPHI A ELECTRIC CCMPANY
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Docket Nos. 50-352 (Limerick Nuclear Generating
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and 50-353 Station, Units 1 & 2)
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DIRECTOR'S DECISION UNDER 10 CFR 2.206 By letter dated April 12, 1979, Frank Romano of Ambler, Pennsylvania, requested that the Commission investigate whether blasting at a quarry near the site of the Philadelphia Electric Canpany's (PECO) Limerick Generating Station has a deleterious effect on the site. Mr. Romano's letter has been treated as a request under 10 CFR 2.2C6 of the Connission's regulations.
Notice of receipt of Mr. Romano's April 12th letter was published in the Feceral Recister 44 Fed. Reg. 33987 (June 13,1979).
In letters dated May 14 anc June 12, 1979, Mr. Romano also raised concerns related to (1) concrete voicihoneycomb in a structure at the Limerick facility, (2) the computer analysis used in the seismic design of safety-related piping, (3) the dis-covery of insufficient gaps between seismic Category I structures, and (4) a request for information from the NRC sant to PECO on April 14, 1978, regarcing the design of safety-related components in the containment builcing.
Mr. Romano requested that repair of concrete void /heneycoco be included in nis request for an investigation of blasting near the Limerick site.
'ahile the sucject of the blasting was covered during the prepa 3 tion of the safety Evaluation Report on the preliminary cesign, it is not clear that 1
two particular issues were acequately treated. One issue is whether the design
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. ground motion adopted for the Limerick plant is adequate to envelop the pectra motion that includes the effect of blasting. The second issue is the potential for displacement along the faults under the facility due tc the blasting.
Before the Staff can affirm its previous conclusion that the nearby blasting would not have a detrimental effect on the facility, the Staff must investigate these matters.~1/
Thus, I have determined that an investigation should be conducted of the effects of blasting at the quarry near the site of the Limerick facility. A geotechnical engineer was sent to the site area in May 1979 and discussed this concern with personnel from NRC's Office of !nspection and Enforcement.
In addition the NRC staff has enlisted the assistance of technical experts from the U. S. Geological Survey.
The U. S. Geological Survey has been requested to evaluate the two specific items described above:
(1) whether the present seismic design bases (ground motions) are adequate to account for the effects of the nearby blasting and (2) the likelihood that the nearby blasting will reactivate old faults at the site. The.1RC staff requested that the U. S. Geological Survey complete its evaluation by December 31, 1979. However, completion by this date is depend-ent en the availability of U. S. Geological Survey reviewers and pcssible need for acquisition of required data from the apolicant.
1/ In this respect the Staff disagrees with the applicant's position in this matter.
In a letter o' August 22, 1979, from its counsel, Troy B. Conner, Jr., the licensee stated that the record concerning the issuance of the construction permi:s indicated that the potential effects of blasting had been fully explored.
. The otner concerns expressed in Mr. Romano's April 12, 1979 letter relating to site geology, fracture zones and the adequacy of the foundations have been addressed in the Safety Evaluation Report issued in November 1971 and in the staff's evaluation of faulting in the excavation issued January 23, 1975.
In these previous reviews of faulting at the Limerick site the staff concluded that (1) the f aults were not capable faults and (2) the methods used to repair the fracture zcnes were acceptable. At this time I find no reason to alter these conclusions.
In any event, review of the Limerick Final Safety Analysis Report will again consider these issues as part of our consideration of PECO's application for operating licenses.
I have determined that a further investigation of concrete void / honey-comb at the Limerick facility is not warranted at this time. Certain concrete voic/honeyccmb were discovered in the Unit No. I containment building while the structure was being built in 1976.
These defects in the concrete were located in seven areas around the personnel air lock penetration and the con-trol rod drive mechanism penetrations. The voids were caused in part by the congestion of reinforcing steel around these penetrations which made it difficult to place the concrete. The locations of the defects are listed in (IE Inspection Report No. 50-352/77-01). In repairing the con-tainment wall, the defective concrete was removec; the steel reinforcing and sound Concrete were left in the area.
The overriding criteria for repairing the concrete are proper placement and strength. Grout, a mixture of sand, water and cement, was the material chosen for the repairs. By design the grout cid not contain coarse aggregate (stones) that are ncnnally a part of concrete. The use of coarse aggregates O
. in concrete reduces the amcunt of cement required; this makes concrete a more econcaical building material when used in large quantities. However, the oaission of the coarse aggregates enhances the grout's ability to penetrate the crevices in the surfaces to which the grout is applied. Al so, the omis-sion of the coarse aggregates dces not lead to a material that has a lower ccepressive strength than that of the concrete used for the centainment walls.
To verify that the grout achieved the recuired compressive strength, test samples were made at the time of grout placement. The samples were allowed to cure and were subsequently tested by PECO. The compressive strength of the sanples was equal to or greater than that required.
The NRC's Office of Inspection and Enforcement investigated :he matter of the concrete void /honeyccmb at the Limerick plant. Inspection personnel followed the matter frem the discovery of the voids /honeyccM5 to the repair of the containment walls. The inspection efforts on this matter are documented in Inspection Reports 50-352 /76-08, 50-352 /76-09, 50-352 /77-01 and 50-352 /77-15, copies of which are enclosed as Enclosure 1.
In summary, the Of fice of Inspec-tion and Enforcement concluded that PECO's resolution of the prcblem was acceptable; therefore, I find that further investigation at this time is not warrantea. Of course, shoula new information beccme available ccncerning accitional honeyccabing in concrete at the Limerick f acility, the Commission will not hestitate to investigate such prcolems or take appropriate action to assure that such deficiencies, if any, are corrected.
Although scecific action was not requested with respect to the other con-cerns raised by Mr. Romano in his letters, the remainder of this decision accresses these concernt. Er.n of these items involves matters subject to
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. either ongoing or future review by the NRC. The item regarding computer analysis and the seismic design of piping systems is the subject of IE Bulle-tin 79-14 (Enclosure 2). This bulletin requested that PECO, among other licensees, take certain actions and report the results to NRC within 120 days of the bulletin. PECO's response was submitted on August 1,1979. In addi-tion to PECO's respcnse to the bulletin, we will review the seismic design of safety-related piping systems during our review of the Final Safety Analysis (FSAR) for the Limerick plant. We expect the FSAR to be submitted by PECO during the sp ing of 1980, and our review of that document will prob-ably start shortly thereafter.
The NRC requested information on April 14, 1978, related to dynamic loads on the containment that were not explicitly considered with the seismic loads at the prelimicary design stage. This request for additional information was sent out to all plants under construction that utilize the Mark II pressure suppression containment. The request is a part of our reassessment of the Mark II containment design wnich began in 1975. In 1975, new pool dynamic loads en the containment were discovered by General Electric (the originator of the Mark II containment). Our reassessment also covers the operation of safety / relief valves. Experience at several operating reactors with pressure suporession containment had shcwn that damage to wetwall interval structures occurred during steam blowdown through the safety / relief valves.
This blowdown produces a dynamic load on components in or attached to the suppression pool.
In the FSA? for the Limerick plant, PECO must show that the Limerick design can withstand the effects of comoinaticns of seismic loads and each of the dynamic loacs.
. Mr. Romano's final concern dealt with the separation gaps between struc-tures at the Limerick plant.
In the Preliminary Safety Analysis Report (PSAR),
PECO cennitted to make the separation gaps between seismic Category I structures twice the distance determined by seismic analysis of the structures. However, during construction PECO found that some of the separation gaps did not meet this commitment; PEC0 reported this matter to the NRC in compliance with 10 CFR 50.55( e). During PECO's study of this matter, a reanalysis of tae seismic design was performed. As described in PEC0's final report dated June 13, 1978, (Enclosure 3) this reanalysis included " realistic consideration of temperature and pressure trane4 ants; structural material and soil properties; soil-structure interacticn; 3rc st ructural and soil danping." Based on the reanaly.is, PECO found that scme of the gaps which would be unacceptable under the original analysis were acceptaale; the balance of the insufficient gaps were increased to meet the PSAR commitment. Mr. Romano's May 14th letter suggested that the reanalysis to justify the as-built gaps resulted in an unacceptable removal of conservatism. This is not necessarily the case. When an applicant uses realistic or "as built" parameters, conservative analysis techniques, anc factors of safety applied to the results of the analysis, an accectable result can be cbtained. Again, our review of the FSAR for the Limerick plant must conclude that the design of the plant is acceptacle before the plant can go into operation.
A ccpy of this decision will be placed in the Cornission's Public Document Roca at 1717 H Street, N. W., Washington, D. C.
20555, and the local public cccument rccm for the Limerick Nuclear Generating Station at the Pottstown Puclic '_ibrary, 500 High Street, Pcttstown, Pennsylvania 19464 A ccoy of b
, this decision will also be filea with the Secretary of the Commission for its review in accordance with 10 CFR 2.206(c) of the Commission's regulations.
As provided in 10 CFR 2.206(c) this decision will constitute the final action of the Commission 20 days after the date of issuance, unless the Com-mission on its cwn motion institutes review of this decision within that time.
FOR THE NUCLEAR REGULATORY COMMISSION,
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7-N:s
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E. G. Case, Deputy Director Office of Nuclear Reactor Regulation Dated at Bethesda, Maryland this 9thday of October 1979
Enclosures:
1.
IE Inspection Reports:
50-352/76-08, 75-09, 77-01 and 77-15 2.
IE Bulletin 79-14 and Revision No. 1; Supplement Mos. I and 2 3.
DECO Report (5/14/78)
_ ENCLOSURE 1
_IE INSPECTICN REPORTS
~50-352/76-08, 76-09 77-01 and 77-15
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