ML17195A052
| ML17195A052 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/14/1983 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Farrar D COMMONWEALTH EDISON CO. |
| References | |
| IEB-80-11, LSO5-83-12-015, LSO5-83-12-15, NUDOCS 8312160059 | |
| Download: ML17195A052 (8) | |
Text
Docket Nos. 50-237/249 LS05-83-12-015 Mr. Dennis L. Farrar Director of Nuclear Licensing Commonwealth Edison Company Post Office Box 767 Chicago, Illinois 60690
Dear Mr. Farrar:
December 14, 1983
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION - MASONRY WALL DESIGN, IE BULLETIN 80-11 Re:
Dresden Nuclear Power Station, Unit Nos. 2 and 3 The staff has reviewed your resp~nses 1
to IE Bulletin 80-11 and found that additional information is required iniorder to complete the review.
The staff's request for additional information (RAI) is enclosed.
Please provide the information by February 6, 1984.
The reporting and/or recbrdkeeping requirements contained in this.letter affect fewer than ten respondents; therefore, OMB clearance is not required under P.L.96-511.
Enclosure:
Request _for Additional Information cc w/enclosure:
See next page 8312160059 831214 I
PDR ADOCK 05000237 I
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DL:~ #5 RGi~~~t 11"'1/~/83
' i i_______.;
Sincerely, Original signed by Dennis M. Crutchfield, Chief Operating Reactors Branch #5 Division of Licensing
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tir. Dennis L. Farrar cc Isham, Lincoln & Beale Counselors at Law One First National Plaza, 42nd Floor Chicago, Illinois 60603 Mr. Doug Scott Plant Superintendent Dresden Nuclear Power Station Rural Route #1 Morris, Illinois 60450 U. S. Nuclear Regulatory Commission Resident Inspectors Office Dresden Station Rural Route #1 Morris, Illinois 60450 Chai man Board of Supervisors of Grundy County Grundy County Courthouse Morris, Illinois 60450 U. S. Environmental Protection Agency*
Federal Activities Branch Region V Office ATTN:
Regional Radiation Representative 230 South Dearborn Street Chicago, Illinois 60604 James G. Keppler, Regional Administrator Nuclear Regulatory Commission, Region III 799 Roosevelt Street Glen Ellyn, Illinois 60137 Mr. Gary N. Wright, Manager Nuclear Facility Safety Illinois Department of Nuclear Safety 1035 Outer Park Drive, 5th Flonr Springfield, Illinois 62704 December 14, 1983
- 1.
REQUEST FOR ADDITIONAL INFORMATION MASONRY WALL DESIGN, IE BULLETIN 80-11 DRESDEN NUCLEAR POWER STATION UNITS 2 AND 3 DOCKET NOS.:
50-237, 50-249 Justify the use of an allowable stress increase factor of 1.67 load combinations containing accident pressures or SSE loads.
is in excess of several factors permitted by the SGEB criteria they are listed below by type of stress:
masonry shear in flexural members 1.3 masonry shear in unreinforced shear walls 1.3 reinforcement takes entire shear 1.5 tension normal to bed joint 1.3 tension parallel to bed joint 1.5 for This
[l];
If any existing test data will be used to justify this increase factor, discuss the applicability of these tests to the walls at the Dresden plant with particular emphasis on the following:
- boundary conditions
- nature of loads
- size of test walls type of masonry construction (block or mortar type, grouted or ungrouted)
The licensee is also requested to indicate the number of walls that would not be qualified if the SGEB criteria were to be used and to specify the percentages of exceedance.
The licensee is advised to explain all conservative measures (if any) used in the analysis to justify this increase factor.
- 2.
Indicate how higher modes of vibration were considered in the analysis.
- 3.
Since Dresden Unit 2 is part of the sysfematic evaluation program (SEP), clarify whether SEP loadings for seismic analysis have been used.
Indicate the criteria used in masonry wall evaluation for SEP loading.
Are they different from IE Bulletin 80-11 evaluation?
If yes, compare SEP evaluation criteria with SGEB acceptance criteria (1) and assess the impact of any devaiations.
- 4.
With reference to the reinforcement in masonry walls, the ACI 531-79 Cod~ [3] specifies that the minimum area of *reinforcement in a wall in either direction, vertical or horizontal, shall be 0.0007 (0.07%) times the gross cross-sectional area of the wall and that the minimum total area of steel, vertical and horizontal, shall not be less than 0.002 (0.2%) times the gross cross-sectional area.
In view of this, clarify whether the reinforced walls at this plant
i
- meet the above requirements.
The licensee is also requested to provide the type and spacing of vertical reinforcement and the total number of vertically reinforced walls.
It should be noted that the horizontal reinforcement is installed to satisfy the minimum reinforcement requirement for a reinforced wall.
With reference to the joint reinforcement, identify the number of walls qualified by the tensile strength of joint reinforcement and indicate the type and spacing of the joint reinforcement.
Based on the review of existing codes and published literature, the NRC does not, at present, approve the use of joint reinforcement as a structural element for unreinforced walls.
If there are unrein-forced walls at Dresden units which have been qualified on the basis of the tensile* strength of the joint reinforcement, the implementation of the attached staff position (Attachment 1) is required to render these walls acceptable to the staff.
If appli-cable, provide schedule and method for the implementation of the staff position.
- 5.
Provide a description of the types of modifications required and their current status.
Provide detailed drawings of some sample modifications and show by sample calculation how they rectify wall deficiencies.
Also, provide a schedule of modification.
- 6.
Provide sample calculations (with explanations necessary to make the calculations understandable) for:
- a single-wythe wall analysis
- a multi-wythe wall analysis
- a stack bond wall analysis
- tornado wind analysis
- interstory drift effects
- block pullout analysis due to attachment
- 7.
Indicate the boundary conditions used in the analysis and verify that they resemble the real physical conditions.
Identify all of the mechanisms used to transfer shear and moment (if any).
If any doubt exists (i.e., whether simply supported or fixed-end condi-tions should be assumed), verify that the assumed boundary condi-tions will produce conservative results.
- 8.
Confirm whether all modifications have been completed and the modified walls are in compliance with the SGEB criteria.
- 9.
The licensee indicated that a masonry wall test program was performed.
Provide the following information:
- number of test specimen in each case
- test procedures in each case
- interpretation of test data
j
'°*,
- - comparison of test data to the values used in the analysis
- 10.
The staff, at this time, does not accept the use of arching action theory to qualify unrerinforced walls.
The staff position on this issue is outlined in Attachment 2.
The implementation of the staff position is required to render walls previously qualified by the use of arching action theory acceptable to the staff. Provide schedule and means by which the staff position will be implemented.
- 11.
In Reference 2, the licensee indicates that the energy balance technique has been used to qualify some of the masonry walls.
The NRC does not accept the application of this method to masonry walls in nuclear power plants without conclusive evidence to justify its application.
The following areas need technical verification before any conclusions can be made:.
o It should be noted that no tests have been performed to date on the post-yield envelope and the hysteretic (i.e., fully reversed cyclic loading) behavior of reinforced concrete masonry walls.
Also, any factor of safety for reinforced masonry walls of the types used in nuclear power plants cannot be used with any amount of confidence because previous tests have not been conducted to failure.
o Provide justification for and test data to validate the appli-cability of the energy balance technique to the masonry.
structures at the Dresden plant with particular emphasis on the following areas:
- a.
nature of the load
- b.
boundary conditions
- c.
type of masonry block
- d.
amount ~nd distribution of reinforcement
- e.
prediction of ductility ratio
- f.
prediction of elasto-plastic hysteretic behavior.
o Indicate the number of affected walls along with their dimen-sions, type of block, and boundary conditions.
o Indicate how compressive failure of masonry and failure of the connection at the boundary were checked.
o Justify by test data the coefficient of friction used in the sliding analysis.
o Provide a sample calculation outlining all steps used in quali-fying a typical wall by the energy balance technique.
- 12.
Drawings submitted in Reference 2 are not legible.
Provide better drawings.
~
- REFERENCES
- 1.
SGEB Criteria for Safety-Related Masonry Wa 11 Eva 1 uati on Developed by the Structural and Geotechnical Branch of the NRC, July 1981
- 2.
B. Ryback (Common\\'1ealth Edison)
Letter to J. G. Keppler (NRC)
Subject:
Dresden Station Units 2 and 3, IE Bulletin 80-11, Masonry Wall Design - Final Revision on 180-Day Report June 6, 1983
- 3.
Building Code Requirements for Concrete Masonry Structures Detroit:
American Concrete Institute, 1979 ACI 531-79 and ACI 531-R-79
1*
ATTACHMENT 1 SGEB Staff Position on the Use of Joint Reinforcing in QLalifying Unreinforced Masonry Walls Introduction The function of joint reinforcement in masonry walls is to prevent the formation of unacceptable shrinkage cracks.
The structural significance (i.e., to provide resistance to tensile stresses) of joint reinforcement in masonry walls is not well established.
Tnis is particularly true for unreinforced hollow block masonry.walls subject to cyclic dynamic loading.
However, some licensees have proposed to use joint reinforcement as a structural element to qualify unreinforced masonry walls in their plants.
The staff and their consultants have reviewed the technical justifications provided by some licensees for using the joint reinforcing (such as 'Dur..
'*lal ')as a structural element in qualifying masonry walls 1*1hich are unreinforced or do not meet the minimum reinforcement requirements of the Uniform Building Code.
The staff has further reviewed the ~est results available in the literature, codes, and other pertinent inform~tion. Based on these reviews, the staff ha~ formulated the following position on~the use of joint reinforcing as a structural reinforcing element in unreinforced masonry walls.
The staff's technical basis for this position is discussed in the attJc~ed report.
I
.9 2 -
Position The use of joint reinforcing as a structural element (to evaluate the capacity of the wall in resisting applied laods) for qualifying masonry walls not meeting the minimum reinforcement requirements with respect to steel ratios, spacing, etc., of the Uniform Building Code-1979 edition is not acceptable*.
Therefore, the licensee shall fix the walls currently qualified by the use of joint reinforcing as a structural element ~uch that they meet the staff's acceptance criteria for unreinforced walls (Appendix A of TER, At~achment 1).
/
- As noted in the attached report, the use of high allowables in joint reinforce~ent, say beyond 30,00~ psi~ even in the *case of reinforced walls is questionable and not acceptable.
However, this position only addresses the use of joint reinforcing in unreinforced walls.