ML20127G576
| ML20127G576 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 10/24/1974 |
| From: | Goller K US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Mayer L NORTHERN STATES POWER CO. |
| References | |
| NUDOCS 9211170382 | |
| Download: ML20127G576 (3) | |
Text
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9 og OCT 2 4 m DISTRIBUTION:
Docket SVarga
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AEC PDR ACRS (16) j Local PDR JRBuchanan, ORNL ORB-2 Reading TBAbernathy, DTIE Attorney, OGC JSaltzman, OA1 Docket "o.'50-263 R0 (3)
SKari NDube WOH111er BJones (4)
PCo111ns R
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Northern States Power Company i
ff, ORO ATTN:
Mr. L. O. !!ayer JShea Director of Naclear Support JSapir Services BScharf (15) 414 Nicollet Mall TJCarter Minneapolis, Minnesota 55401 Ret Change to Bases Gentlenen:
In a letter dated May 10, 1974, you transmitted the results of your eddy current inspection for inverted poison tubes and an analysis of the potential effect of B C compaction in the inverted poison tubes 4
in the Monticello Nuclear Core Control rods.
A total of 19 inverted tubes in 15 control rods (0.19% of the total tubes in all control rods) were lef t inside the core. The potentini shutdown nargin loss assuming full D C settling in these 19 inverted tubes was calculated to be 0.04" Ak. 4This value should be added to the shutdown margin requirenants (included in the value of R) ns long as these blades remain in the core. You concluded, and we agree, that the potential effects of 3 C settling on the rod drop accident and pressurization l
3 transients are negligible.
We have reviewed your submittal and concluded that the presence of 19 inverted tubes does not significantly alter previous safety considera-I tions. Accordingly, the three requirements specified on the first page of the letter from D. J. Skovholt dated April 1, 1974, pertaining to inverted poison tubes are no longer applicable.
To impicment the above requirements, the bases for the Technical Specifi-cations appended to License Ho. DPR-22 are changed by revisin6 the second paracraph of Section 3.3. A.1 to read as set forth on the enclosed revised i
page 82 of the Technical Specifications.
Sincerely, Origina! ?!cned by a Kuri R Gaer Karl R. Goller, Assistant Director 9211170382 741024 for Operating P.eactors PDR ADOCK 05000263 Directorate of Licensing P
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. Form Aic 318 (Rev. 9 53) AECM 0240 W u. s. novsnmessm? Paintime orrics s,74.s s.see
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';orthern States Power Coc:pany ec v/enclosuret i
j Arthur Renquist, Escuire Sandra S. Gardebring Vice Prcaldent - Law Special Assistant Attorney General Northern States Power Company Couneci for Minnesota Pollution 1
414 Mico11et Hall Control Agency
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Gerald Charnoff Shaw, Pittman, Potts, Trowbirdge Anthony Z. Roisman, Esquire and Madden Berlin, Roisman and Kessler 910 - 17th Street, N. U.
1712 'I Street, !!. W.
ashington, D. C.
20036
~4ashington, D. C.
20006 Howard J. Vos:el, Esquire Environmental Library of Minnesota Lo;;ni Counsel 1:22 S. E. 4th Street i
2750 Dean Parkway Minneapolis, Minnesota 55414 j
tiinneapolia, tinnesota 55416 9teve Cadler, P. E.
2120 Carter Avenue T. t. Paul, Minnesota 55108 Mr. Daniel L. Picker Assistant City Attorney 638 City Hall cc. Paul,:!innesotn 55102 Ken Dzugan, Director City of St. Paul Pollution l
Control Services 100 East 10th Street St. Paul, Minnesota 55108 Warren R. Lawson, M. D.
Secretary & Executive Officer
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State Department of Ucalth 4
717 Deinware Street, S. 2.
i Itinneapolic, Minnesota 35440 0F FIC t >
SURNAMEW
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DATED form AEC 318 (Rav. 9-53) AECM 0240 W u. s. o0VERNM ENT PRINTING OFFICEA 1974 32941,8
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Bases Continued 3.3 and 4.3:
A.
Reactivity Limitations f
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1.
Reactivity Margin - core loading r
t The core reactivity limitation is a restriction to be applied principally to. the design cf new i
Satisfaction of
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fuel which may be loaded in the core or into a particular refueling pattern.
the limitation can only be demonstrated at the tine of loadicg and must be such that it will
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apply to the entire subsequent fuel cycle.
The generalized fot., is ther. the reactivity of the -
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core loading will be limited so the core can be made subcritical by at least R + 0.25% Ak in the most reactive condition during the operating cycle, with the strongest control rod fully j
j l
withdrawn and all others fully inserted. The value of R in 7. /,k is the amount by which the core l
reactivity, at any time in the operating cycle, is calculated to be greater than at the time of l
the check; i.e.,
the initial loading.
R must be a positive quantity or zero. A core which con-tains tenporary control or other buinable neutron absorbers may have a reactivity characteristic
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which increases with core lifetime, goes through a maximun and then decreases thereafter.
Figure 3.3.2 of the FSAR for such a curve.
l The value of R is the dif ference between the calculated core reactivity at the beginning of j
the operating cycle and the calculated value of core reactivity any time later in the cycle l
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where it would be greater than at the beginning. The value of R shall include.thd potential in the shutdown margin loss assuning full BtC settling in all inverted poison tubes present i
New values of R must be calculated for each new fuel cycle.
-i core.
The 0.25% ak in the expression R + 0.25% ak is provided as a finite, de=onstrable, sub-E j
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criticality margin. This margin is deconstrated by full withdrawal of the strongest rod and partial withdrawal of an adjacent rod to a position calculated to insert at least e
l R + 0.25% ak in reactivity. Observation of sub-criticality in this condition assures least a R + 0.25% ak j
sub-criticality with not caly the strongest rod fully withdrawn but at margin beyond this.
i 2.
Reactivity margin - stuck control rods Specification 3.3. A.2 requires that a rod be taken out of service if it cannot be moved '
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b 82 i
j 3.3/4.3-8
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