ML20148H297
| ML20148H297 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 03/16/1978 |
| From: | Ziemann D Office of Nuclear Reactor Regulation |
| To: | Groce R YANKEE ATOMIC ELECTRIC CO. |
| References | |
| NUDOCS 8011170936 | |
| Download: ML20148H297 (4) | |
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DISTRIBUTION Docket RBaer C
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MAR 101978 0 ELD Yankee Atomic Electric C$n'yG 1978.
iean ATTN: Mr. Robert H. Groce ABurger.
i Licensing Engineer
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20 Turnpike Road 7, Westboro, Massachusetts 0158'.1..
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- JTBAbernathy 7k.
v' v. Gentlemen:.,J J
......- J.JRBuchanan U ~
r 1 ce)nse amendment dated RS 16 This is in response to your ap.p_lication December 14, 1977, which supdrsides 'you'r iriitiaf'apiplicatifon dated
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September 8,1977. You propos!ed ac.hiange' td'the Techn'ical Speciff-cations for the Yankee-Rowe reactor to reduce t,he r,cquired numbe.r of operable incore scutron detectors'from 17 to 12..
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C W,, We have reviewed your request"and f,ind that the additional infamation
$.i review.
We havo discussed ttig items in the enclosure durin tel ephone conversati ons with y.o'.u.'r.' i.t.'af.f..",..,7... "...' ~..."..~.."...~g. recent...... ". ' '
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To maintain our review scheduTe your response is required by April 10,1978.
Please provi.de youf'scriedul'e' ~fdrs'ubniit tal of' '
this information.
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Request for Additional ~
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~THIS'000UMEDL CONTAWS
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CONCERfiliu; 11:0P05tD id !?'CilSi 0F U:tME f1EUlR0ii DE f f C f 0a illh'.la i. Al Y/ m lL l:U.1 D OC):i.1 i:U. !> 0- 2 9 Ri' 1.
Provide the results of your study that demonstrates the Loility to detect fuel misloadings during startup tests with the reduced compliment of inco.'e detector thimbles, considering the following:
a.
The incore detector sysic.i must bc able to detect severe fuel misloadings.
The most sevcre misloadings which would go undetected should he computed, and the presence of such
'r a uisloading should be assumeri in the preparation of the k"AM technical specifications. A 2D PDQ for the misloaded core d~
should be adequate to generat e activations to be used in this study. A suf ficient number of casec should be run to give a ueaningful statistical data base.
2.
Provide 'the results of your r.tudy to determine the increased uncertainty in the Waking factor <. when they are computed f or use of the reduced compliment of incore detector thimble;,
I m considering the following:
- gjfyi, a.
Increased incertainty during operations could be addressed in two ways.
Whichever method is chosen, a sufficient number of cases should be run to give a r,!eaningful si-atistical data base.
(1) ~ Compare previous cycle maps.
NN (a) Take activation signals from previous raps.
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(b)
In a rand:n fashion discard all but il of these d$O-a c'. iva t i on s.
(c ) Run ItiCORE with these ti activations.
(d) Compare these It! COPE results with those obtained gM in the original map to determine the increase M*
in uncertainty, h2Y-
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febM N (2)
- Compare with PDQ J$,.
(a) Run PDQ which coupstes detector activations and
'IAw ns power distribution (b)
Pick a random sample of fl of these activations.
f.,#g7 (c) Run I?!CCRE with these !! activations.
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(d)
Compare t.hese It CCRE results with the PDQ results i" V I to determine the uncertainty due to the synthesis 80 procedure.
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Describe how you plan to monitor core tilt, and provide your gy analyris to support the proposed method.
In addition, please plfy.
respond to the following:
A Monitoring core tilt via loop flaws and temperature has a.
been suggested by Yankee Rowe.
Has this uethod been duaonstrated viable?
b.
It <,eems reasonable that the technical specifications be revised to require t hat at least one set of quadrant h,W' '
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syuattric detector paths remain operable which would
,i' be used te monitor core tilt.
If the core tilt is to be based on thir only, then the four trace <, (one per quadrant) should be taken in succension.
- Further, to check the data, these f reces should be taken ente at the beginning of the inap and once a t the end.
4 propose changes to the Technical 5pecifications, as appropriate, L..
based on the results of the altve studies for the reduced
- N, compliraent of incore neutron detec tor thimbles.
for your h-W$
response you may consider the following:
Call the ntoaher of rc.aolning opei able pa ths N.
Ther a.
will be uncertainty in the results 01 incore mea surements when N is reduced below some critical (yet to be determined) number.
Below this critical number the uncertainly will increase at N decreases.
This increased uncertainty should i
be factored into the technical specifications. Maximum
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operatirig flexibility at all times would be assured if the f
uncertainty factored into the technical specifications were a function of the current value of N.
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