ML20087M333
| ML20087M333 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 03/02/1984 |
| From: | Woolever E DUQUESNE LIGHT CO. |
| To: | Starostecki R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| Shared Package | |
| ML20087M328 | List: |
| References | |
| 2NRC-4-022, 2NRC-4-22, NUDOCS 8403290204 | |
| Download: ML20087M333 (4) | |
Text
%
2NRC-4-022 (412)787 - 5141 Telecopy 8-29 Nuclear Construction Division March 2, 1984 Robinson Plaza, Bu;lding 2, St;ite 210 Pittsburgh, PA 15205 United States Nuclear Ibgulatory Ormission Region I 631 Park Avenue King of Prussia, PA 19406 ATTENTICE:
Mr. Richard W. Starostecki Division of Project and Resident Programs
SUBJECT:
Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 USNRC IE Inspection Report No. 50-412/83-13 Supplement Response Ietter Gentlemen:
Wis letter provides additional information relative to our pre'vious response to the NRC Inspection Report 50-412/83-13 and as conmitted in Refer-ence 1.
The engineering evaluation to determine if the current installation is acceptable has been completed and is stenarized below.
ENGINEERING EVALUATION Problem Description he applicable portion of the Specification for Structural Joints Using ASTM A325 or A490 Bolts dated April 18, 1972, is:
" Structural plate washers or a continuous bar not less than 5/16 inch in thickness are required to cover long slots that are in the outer plies of joints. %ese washers or bars shall have a size sufficient to completely cover the slot after installation."
%e primary reason for this requirement is to ensure that the minimum required bolt pretension is maintained.
Another reason for the requirement
.is to protect uncoated joint camponents from possible errosion.
BVPS-2 has installed approximately 786 structural joints with 3/4 inch diameter or 7/8 inch diameter ASTM A325 bolts, standard circular - washers under both head and nut, and long slotted holes in the outer plies of the joint.
BVPS-2 has also installed an undetermined ntaber of structural joints with 7/8 inch diameter ASTM A325 bolts, 5/16 inch plate washers, and long slotted holes in the outer plies of the joint.
The plate washers are sized to conpletely cover the slots when the bolts are centered.
Ibwever, in nost of the connections, one end of the slot is exposed.
8403290204 840322 PDR ADOCK 05000412 G
Ohited States Nucle r Regulatory (bnmission Mr. Richard W. Starostecki Page 2 Ebr both of the above, mnnected parts are predominantly ASTM A36, although higher strength materials may have been used.
Material substitutions are docmented but were not retrieved since it is conservative to assee A36 in this instance.
Bolt Pretension 1
'Ibe ASW A325 bolts installed in the above described configurations maintain the required minime bolt preload. W e loss of initial preload is no greater than normal (approximately 5 percent to 10 percent).
tis is substantiated based upon the calculated bearing area between the standard round washer and the slotted connected part and the allowable bearing pressure as determined from the following:
l.
Journal of the Structural Division, ASCE, Vol. 94, No. Sr9, September, 1968, " Bolted Joints with Oversize or Slotted Holes," by Ibnald N. Allan and John W. Fisher.
2.
" Guide to Design Criteria for Bolted and Riveted Joints," by John W.
Fisher and John H. A. Strnik, John Wiley & Sons, Inc., 1974.
J
%ese references, based upon a testing program performed at Lehigh Univer-sity, established that a loss of preload does not occur if the bearing area between washers and connected parts results in bearing stresses less than an j
allowable value for ASTM A36 connected parts.
It has been aanfirmed that the calculated bearing pressure, based on required minimum fastener tension, is less than this allowable bearing pressure.
Werefore, the long slotted hole connections at BVPS-2 maintain a bolt tension in excess of the required minimm' bolt preload.
Wese structural joints at BVPS-2 were installed by turn-of-nut tightening with 100 percent SOC witnessing of the installation.
In addition, SQC witnessed the torque obtained with calibrated wrenches on a minimum of 10 percent of the bolts, using at least two bolts per connection.
%is is verification that the required minimm bolt preloa3 was achieved.
To allow uniform installation procedures, the " Specification for Structural.
V Joints. Using AS'IM A325 or A490 Bolts" requires ecactly the'same plate washer for ASTM A325 bolts as for A490 bolts.
Ibwever, required minime fastener tension is at least 25' percent greater for A490 bolts.
%is results _ in reduced bearing stresses and conservative structural joints with A325 bolts.
Joint Protection
%e joint protection afforded by a plate washer coupletely covering the long slot is unnecessary for the projected environment at BVPS-2.
We intent of this requirement is to provide the same degree' of ' sealing protection as normal, oversize, or short slotted holes for all exposures.
Wese types of holes are not watertight, but do prevent foreign material from' entering the holes. We mnnections with partially covered long slots at BVPS-2 are located inside heated industrial structures.
Relative humidity between 20
United States Nuclear Regulatory Omnission Mr. Richard W. Starostecki Page 3 l
percent and 90 percent is maintained.
Sprays, mists, or corrosive chemicals are not present.
In this environment, the degree of additional protection provided by completely covering the long slots is unnecessary.
Summa _ry
%e engineering evaluation has confirmed that the ASTM A325 bolts installed maintain the required minimum bolt preload.
We additional joint protection afforded by p} ate washers co:pletely covering the long slot is unnecesary for the environment at BVPS-2.
No additional action need be taken in regards to the installed condition.
DUQUESNE LIGFff COMPANY h G Se By F at E..$. l.u E. J. Ecolever Vice President JS/wjs cc: NRC Doctment Control Desk Mr. G. Walton, NRC Ibsident Inspector Ms. L. Lazo, Project Manager
REFERENCES:
- 1) 2NRC-9-098, dated December 8,1983
- 2) NPC letter Docket No. 50-_412, dated November 10, 1983 SUBSCRIBED AND RN 'IO BEFORE ME THIS MDAY OF s,, / )
, 1984.
f (Ya 5~LA) e
~-
Notary Public ELVA G. LESONDAK, NOTARY PUBL!C CCB!NSON TOWNSH'P, ALLEGHENY COUNTY
?,1Y COMMISSION EXFIRES OCTOBER 20,1986 i
l l
l
I
./
e,,
' United States Nuclear Regulatory Commission Dr. Richard W. Starostecki Page 4 COMMONWEALTH OF PENNSYLVANIA )
) SS:
COUNTY OF ALLEGHENY
)
af 9Ih,beforeme, a Notary On this AM day of ~
,/
Public in and for said Commonwealth.ind County, personally appeared R. J.
Washabaugh who being duly sworn deposed and said that (1) he is duly authorized to execute and file the foregoing Submittal on beh'alf of E. J.
Woolever, Vice President of Duqu2sne Light, (2) he is duly authorized to execute and file the foregoing Submittal on behalf of said Company, and (3) the statements set forth in the Submittal are true and correct - to the best of his knowledge.
'O A.
Notary Public.-
ELVA G. LESONDAK, NOTARY PUBLIC RCBINSON TOWNSHIP, ALLEGHENY COUNTY MY COMM!SSION EXPIRES OCTOBER 20,1986 1
1 t
4 d
I l
')
,