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PUBLIC SERVICE COMPANY OF COLORADO
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January 19,;1972 f Doctttt!
C2EC " l
. Secretary.
JAN241$ l U. S. Atomic Energy Cormnission Washington, D. C.
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Attention: ' Chief, Pubite Proceedings Branch'
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1 2-January 19, 1972 ivni,e scenes ce=aar o cm... '
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for power eeneration must be' designed to remain o:erable for this condition.'
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It seens clearly-beyond the scope of safety censi:aratiens to include a re-l quirerent that a plant shall be capable of power ge.eratien following'an
" perating Easis Earthqucke." As long as syste's related to safety are des 1
' signed to rer. tin operable following;an " Operating Iasis Earth:uake," it seec':
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to 'us that the extent to which the,rerainder of th clant.is cesigned to re-
.r.ain operable following such 'an event should rerain as a decisien to be rado
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by the apr.licant. We recor:rtend that the definiti:n which was creviously oro.
posed in the AEC tentative criteria should be ad::ted in.orinciale. The foi.
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. lowing wording, containing minor eettorial revisi:ns, is reccanded:-
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"The ' Operating Basis Earthouake' is that earth:uake which would produce a vibratory ground mtien equal to that vi-bratory ground rotion' for which:those features r.ecessary.
for continued operation without undue risk to the healthL and safety of the public are designed to re:r.ain functional."-
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Paragraph !!! (g) (1):
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Based on' historic evidence, the probability is very srall that a -
fault which has not shown evidence of nevert:ent wi-him the last few tens of thousands of years could generate a major eartheuike. Since technktues for l 'i establishing tires of neverent beyond 35,000 years er so a;: ear to be of -
i debatable validity, we believe that the burden to show that a ft. ult has not
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moved more than once in.the past.500,000 years tends.. to niace all detectable faults within the category of active faults' -
We recommend that.the phrase, "or rmre than once in the' past'
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,, 500,000 years........-.s.." hould be deleted. -
Paracraoh IV (a) (5):
The phrase " historically reported eart* quakes." fr:o.l.tes. reporting -
through forrally establish'ed channels which might r.ct crevirte for the existance of-other documentation which may exist within the vicinity of a site.
We suggest that you. night.wish to' censider a revisien sording such as,follows:
"1.isting of all known historic -eart.1::akes-for,.hich-decurentati:n l is avaliable which have affected er e-ich could be reasonably ex-pected to have af fected the site...."-
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Paragraph IV (b):
The requircrnent to perform a detailed inveiti;ation for faults 10.'$
feet long ray be unduly conservative if extended to a' ra:!ics of five' r:iles.
Since there is littic, if any, evidence to sugnest tht: a significant meth.
quake could be tienorated by a fault ICC1 feet 1c.r;, investi*ptir,n ofilt, Inss_,than one mile long would not apoear to be reqensary for thr: cntirn arN-.l
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encompassed by a radius of five mi.l.es.'-
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January 19. 1972 n.s.c si.v.cs coun=, or cotoaao'o f
'ParaqraphVI(b):
Please refer to the content regardina Paragrsoh it! (d):
- We will appreciate your consideration.of the above coc:nents.
Very truly yours,
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ll.t'.l.:s' R. F. Walker. Vice President Engineering and Planning
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Electric Department Rn!/jk'
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