ML19330B487

Forwards Response to NRC 790809,0918 & 1018 Ltrs Requesting Review of Matl Relevant to Determining Facility Response to Nearby Quarry Blasting.Blasting Will Not Cause Damage to Any Class 1 Structures

ML19330B487
Person / Time
Site:	Limerick
Issue date:	07/25/1980
From:	Devine J INTERIOR, DEPT. OF, GEOLOGICAL SURVEY
To:	Rolonda Jackson Office of Nuclear Reactor Regulation
References
NUDOCS 8008040082
Download: ML19330B487 (4)

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.V-fM4 United States Department of the Interior

~ )- GEOLOGICAL .it'RVEY RESTON. VA. 22092

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UWICE OF T!{E D2ECTOR ,.

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In Reply Refer To: . . . . July 25, 1980 EGS-Mail Stop 106

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Dr. Robert E. Jackson Chief, Geosciences Branch Division of Engineering Mail Stop P-314 U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Dear Bob:

Enclosed are comments in response to the August 9, 1979, letter from Mr. Frank Schraeder and to your letters of September 18, 1979, and October 18, 1979, requesting that the Survey review material relevant to determining the response of the Limerick Generating Station, Units 1 and 2, Docket Nos. 50-352/353, to nearby quarry blasting.

This review was performed by me, and we have no objections to your

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making this review part of the public record.

Sincerely yours,

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N (JamesF.Devine

' Acting Assistant Director for Engineering Geology Enclosure t

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2 i Limerick Generating Station Units Scs 1 S 2 The 'fo11owing comments result from the detailed review of the geological and seismological portion of the Limerick Preliminary Safety Analyses Report, the Dames and Moore geologic reports of September 19, 1974, a variety of material 3,"

submitted by the applicant in response to requests by the Nuclear Regulatory Commission concerning the blasting issue, and a personal inspection of the ,

site and interviews with' the _ operators of the Pottstown Trap-Rock Quarries, Inc.

I'have examined in particular detail the blasting practices of Pottstown Trap-Rock Quarries, Inc., and compared them with the standard practices of the industry in general and with the ones used for the extensive vibration from the quarry blasting research program of the U.S. Bureau of : lines from 1961 to 1967 of which I was the Project Leader. The ground response characteristics

j. observed during that research period were from a wide variety of rock types and blasting parameters including ones very similar to those at the Pottstown quarry.

It is the position of the Pottstown Trap-Rock Quarries, Inc. , that with ;

quarry face height less than 100 feet the maximum explosive charge weight per time delay (a controlling parameter for ground response, see Ref. 2).will not

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exceed 400 pounds. Based on my experience, additional charge weight per delay would result in poorer rock breakage and, consequently, there is no reason to increase that parameter beyond the 400_ pounds.

Examination of the sites of both the Limerick plant and the Pottstown quarry and statements of officials of both operations indicate that the maximum dis-

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tance possible from any quarry blast to the nearest Class 1 structure is 2000 feet.

i To -understand the significance of these numbers, one should consider the rela -

tionships, developed in References 1, 2, 6 3, of ground motion, explosive charge weight, _ and distance as ' follows:

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V ='H ( )-B where V = peak particle velecity in in./sec.

D = distance from measurement point to blast area in feet N = charge. weight per time delay interval in pounds H = particle velocity intercept at unity scaled distance From this relationship and fr experience developed from many blasts, the concept of ~a scaled distance ~ ) equal to 50 ft./lbb results in the maximum s~

particle velocity (ground moti n) of about 0.4 in./sec. Since this value of

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particle . velocity,is 1/5 that Lof the Pennsylvania State Blasting Code Criteria for~ safe ground motion, it -is etnsidered to be a safe amount of ground motion allowable without' seismic monitoring equipment.

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2 From the parameters of the Pottstown Trap-Rock Quarry's blasting (400 pounds per charge weight delc,* and minimum distance of 2000 feet) one gets a scaled distance of 100 or conversely, at 2000 feet one would need 1600 pounds per delay to reach a scaled distance of 50. Also, there are several other fac-tors that add _large margins of safety to the ground motion values expected at the Limerick plant. For example, scale distances much less than 50 are

. . permissible if seismic recording instrumentation is used (as is the case at L

' Limerick). . Secondly, the 2 in./sec. maximum safe ground motion is for

ordinary structures without any seismic design. Obviously, the design of the Limerick plant exceeds that of ordinary structures.

Additionally, the geometry of the positioning of the ' rock strata results in .

an expected groiind motion less than average for that rock type. This is

because the Limerick plant is stratigraphically lower than the quarry. Con-l sequently, the strata in which the blasting occur, when projected to the Limerick site, would be many feet above the Limerick Plant.

Consequently, there are sufficient safety margins throughout the blasting and ground motion calculations that, it is my judgment, blasting at the Pottstown Trap-Rock Quarries. will not cause damage to any Class 1 structures at the Limerick plant. Blasting procedures would have to be changed drastically for this judgment to be invalidated.

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References

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JDevine,LJames F. .(1966),l Avoiding Damage to Residences from Blasting Vibrations:

Highway Research' Record No._135,. National Research Council, National

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Academy of Sciences--National Academy of Engineering

- Devine, James F., Richard H. Beck, Alfred V. C. Meyer, and NilburLI. Duvall

_(1966), Effect of Charge Neight on5 Vibration Levels from Quarry Blasting:

U.S. Bureau of Mines--Report .of Investigations 6774

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Duvall, Nilbur .I. , and James F. Devine (1968) , ~ Avoiding Damage .by Air Blasts and Ground Vibrations from Blasting: Surface Mining, AIME Duvall, W. I. , and David E. Fogelson- (1962), Review of Criteria for Estimating

, Damage to Residences from. Blasting Vibrations: U.S. Bureau of Mines--

• Report of Investigations 5968 j' Fogelson, David E. , C. H. Dowding '(1977), Bureau of Mines Research on Response f of Residences to Ground Vibrations from Blasting: 18th Symposium on Rock:

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Mechanics, Keystone, Colorado I

Leet,: L. Don (1974), Effects Produced by Blasting Rock: Hercules, Inc.

l Thoenen,. J. R. , S. L. Windes (1942), Se'ismic Effects of Quarry Blasting: U.S.

Bureau of Mines Bulletin 442 4 -

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