ML19256D267
| ML19256D267 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/20/1971 |
| From: | Case E US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 7910170780 | |
| Download: ML19256D267 (5) | |
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FEB 2 0 1971 Peter A. Morris, Director Division of Rasetor Licensing THREE MILE ISLAND UNIT NO. 1, DOCKET RO. 1 DOCKET No. 50-289 Adequate responses to the enclosed request for additional infor-nation are requited before we ten ecapista our review of the subject application. These reqsests, prepared by the DRS Struc-tural Ragineering Branch, concesa the containment and Class I structural design material presented in Amendments 15 and 17 of the application. Question 5.22 of the original question list has not been responded to by the applicant.
Original,lgned by E. G. Case Edson C. Case, Director Division of Reactor Standards Raclosuret Esquest for Additional Information for IMI No.1 cc w/ encl S. Manauer, DR R. DeYoung. DRL R. Boyd, DEL D. Skovbolt, DEL Distribution R. Haecary, DES C. Long, DEL SUPPL
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T!!REE MILE ISLAND UNIT NO.1 Docket No. 50-289 ADDITIONAL INFORMATION REQUEST 5.1 (a) Discuss the design approaches used which take into account the effect of transient thermal stresses on parts of structures with variable thickness, such as trasitions between the buttress and the wall, between the wall and ring girder, be-tween girder and doce, in thickened part of wall at large openings and, in general, in areas of local thermal stress concentratina. Consider also parts of structures where, in consequence of exposure to different temperature conditions, non-uniform tenperature distribution may develop.
(b) Discuss whether the containment design can withstand a temper-ature higher than the LOCA design temperature at a pressure 7
lower than the LOCA design pressure.
I 5.2 The ACI Code 318 considers 0,85 f, as ultimate strength of concrete in bea=s and not as an allowable stress. Also, the ultimate strength-of concrete is decreased when tensile stresses or tensile strain occur in the direction perpendicular to the 0.85 f compression.
Justify, therefore, your design approach which neglects these two factors.
(pp. 5-17,17a,18) 1450 143
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5.3 (a) Bond and anchorage stresses permitted in ACI 318-63 Code are not suf ficiently conservative for nuclear containment struc-tures since the Code does not cover the case of axial tension in the direction perpendicular to the reinforcing bars nor cases with high thermal stresses. Demonstrate that the values of the allowable 'and ultimate bond and anchorage stresses used-in your design are adequate.
(b) The referenced report entitled, "A Study of the Design and Construction Practices of Prestressed Concrete and Reinforced Concrete Containment Vessels, Final Report F-C2121" August 1969 by Chen Pang Tan of the Franklin Institute Research Laboratory does not contain sufficient experimental data to justify the
" allowable stresses and yield strengths" specified on pages 102-107. Demonstrate that the values of allowable stresses and ule.imate stresses used as specified in the ACI 318-63 Code are applicable under conditions where (1) one or two principal stresses are tensile and (2) one or two principal stresses are zero but the corresponding strains are tensile.
(c) For the case where the reinforcing is not parallel to the principal stress, discuss the manner by which the design takes into account the influence of the shear stress on allowable and ultimate compression stress.
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(d) Load factors are intended as margins to take into account not only to the probability of occurrence of a system of loads but also cover the uncertainties of load distribution and stress and strain analyses. A load factor of 1.0 means that the design is done for rupture. Justify this approach by
.. demonstrating..that eyen with.this. approach a. f actor _ of. safety-,
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larger than 1.0 is achieved.
5.4 Demonstrate that the tendon anchorage zone tensile stresses will not reduce the concrete ultimate compressive stress below design level, and that there is a sufficient margin of safety under all loading conditions.
(pp Sd-2, 3 and 21a) 5.5 Explain whether tensilo stress concentrations have been included when translating results of the plane stress finite element method used in your design into rtsults corresponding to actual three-dimensional stress and strain distributions in the structures.
(pp. 5d-9, 10) 5.6 Justify the omission of reinforcing at locations in the inside face of the wall and dome as well as around liner anchors, where tensile stresses are expected in the concrete.
Since concrete cracking is a function of shear and normal compression as well as normal tension, explain how the design takes into account such cracking.
In regions of concrete tensile stresses, specify the measures taken in the splicing and anchorage of the reinforcing.
(pp. 5-44, 44a, 45) 1450 J45
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'5. 7 Tendon surveillance is intended to provide a check on potential cor-rosion under stressed conditions, which may occur under loading conditions in service. Since the proposed tendon surveillance pro-grams do not adequately take this factor into account, either submit a modified tendon surveillance program including the statistical basis for tendon sampling, or provide further justification of the basis for and adequacy of yes r proposed program.
(p. 5-21) 5.14 List the alicuable bearing values for different foundations, including the allowable increase for dynamic conditions, and indicate the criteria by which these stresses have been established.
(pp. 2-39, 40, 67) 5.24 Justify your bases for limiting defor=ation checks to three meridions of the contain=ent structure during the structural acceptance test.
Although three checks may be adequate for an ideal cylindrical structure, the as-built geometry of structure may include ovality and out-of-roundness characteristics which may dictate the need for more than three control meridions to assess the effects of load reactions during acceptance testing.
5.25 In conjunction with your proposed seismic instrumentation program (page 5-11 of the FSAR) submit your plan of action based on the interpretation of the recordings obtained from the instruments in the' event of an earthquake occurring at the site, as related to the actual design capability of the plant to withstand seismic loadings.
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