ML20024G794
| ML20024G794 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 08/09/1973 |
| From: | Mayer L NORTHERN STATES POWER CO. |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 9104300422 | |
| Download: ML20024G794 (6) | |
Text
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M3 NSR3 NORTHERN STATES POWER COMPANY M I N N E A f* O L.l e, M I N N E S OT A 55401
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'e Ci Mr. J F O' Leary, Director s
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Dear Mr. O' Leary:
MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Supplemental Information to Cycle 2 Startup Report
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1he third paragraph of Section V, Startup Testing, of our Cycle 2 Startup Report submitted July 12, 1973 descrites startup tests done to confirm core calculations. Because of recent questions and telephone discussions on that subject we are submitting the attached information which expands that paragraph.
Yours very truly, cx ' O. 91< q /
' O Mayer, PE Directoe of Nuclear Support Services LOM/MHV/sf cc:
B H Grier G Charnoff Minnesota Pollution Control Agency Attn. K Dzugan 9154 k,043OO422730909 p
ADOCK 05000263 PDR
MONTICELLO NUCLEAR GENERATING PIANT SUPPLEMENTAL INFORMATION TO CYCLE 2 STARTUP REPORT Startup testing was done to confirm core calculations which were unde by both General Electric and Northern States Power. Shutdown margin demon-strations were done at cold conditions with the most reactive control rod withdrawn.
Rod 06-31 was calculated to be the strongest rod; its worth, with all other rods inserted, was calculated to be.0334 delta k.
Rods adjacent to the strongest rod had claculated worths of the order of.0315 delta k; control rods of this strength have very large individual notch worths over the range of interest. Therefore, a diagonally adjacent rod was withdrawn to demonstrate sufficient shutdown margin. The core was xenon-free with a samarium concentration at the time of testing greater than the equilibrium operating level by an equivalent of.0024 delta k.
The test objective was to demonstrate a shutdown margin including transi-ent poison effects in addition to the.0025 delta k shutdown margin re-quired by Technical Specifications. This required that a.0049 delta k shutdown margin be demonstrated. To meet this requirement rod 06-31 was fully withdrawn and rod 10-27 van withdrawn to position 08.
This and symmetric locations were determined to be the most reactive areas of the core by both GE and NSP calculations. The 08 position on rod 10-27 represented.0084 delta k as calculated by NSP. Calculations identified other rods having relatively high worth; a total of five test cases were established as listed below.
Suberiticality was verified in each case.
Shutdown Margin Partially Withdrawn Rod Verified With Case Rod Full Out location Position One-Rod-Out A
06-31 10-27 08 0084 delta k B
30-47 26-43 08
.0084 delta k C
06-27 10-31 08 0089 delta k D
18-27 22-31 08
.0098 delta k E
26-27 22-31 08 0100 delta k Figure 1 identifies control blades fabricated in Wilmington with darkened circles. The letters on that figure identify the location of rods used in each shutdown margin demonstration case; numeric subscripts indicate the position of each control rod.
(Position 00 is fully inserted; 48 is fully withdrawn. Withdrawal to position 08 is equivalent to a 24" with-drawal from fully inserted.) Adequate shutdown margin was verified in the region of influence of numerous Wilmington fabricated control rod blades.
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The core has been operated with quadrant symmetric control rod patterns to J
establish a synnetric exposure distribution.
Shuffling and new fuel addi-tions during the recent refueling outage maintained that symmetry.
During i
cycle 2 startup testing the symmetry was verified.
The control rods-l represented by single circles on Figure 2 were fully withdrawn according j
to the norum1 rod withdrawal procedure. Four in-sequence rods, identified l
by double circles, were adjusted to determine similar critical patterns.
l All other rods ranained fully inserted. Critical configurations were determined to be:
j Rod Positions 3
Test l
Case 26-35 26-19 34-27 18-27 IA 48 00 08 00 IB 48 00 00 08 II A 08 00 18 00 II B 00 10 18 00 III A 00 10 00 48 j
III B 00 10 48 00 In the dispersed control rod pattern shown, the reactivity worth of an individual notch is generally very low. One notch (two_ positions) is the smallest discrete step of control rod movement available. Demonstrating criticality within one notch confinns the synunetry of core reactivity.
This was done as is borne out by the above tabulation of critical rod configuration data.
Each control cell represented on Figure 2 is a 12-inch square. For the critical rod configurations. tabulated above, the critical array centers around a 36-inch square island; control rods to the periphery of that island are coupled very loosely.
Likewise, the effective i
height of the island includes only a short section near the top of the core.
It was shown that a rod at position 48, as in cases I and III, contributes no more than a rod at position 18, as in case II.
The most reactive part of the critical array is the upper 24 to 30 inches of the core which corresponds to control rod positions 08 to 10.
This demonstration veri-fled that synnetry of reactivity exists in the top region of the reloaded i
Core.
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02 06 10 14 18 22 26 30 34 38 42 46 50 FIGURE 1
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CONTROL NO:
6154 FILE:
FROM: L. O. Mayer DATE OF DOC DATE REC'D
' LTR MEMO R1 I OTHER Northern States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401 8-9-73 8-13-73 x
TO:
SENT LOCAL PDR x
J. F. O' Leary 1 signed 39 CLASS UNCLASS PROP INFO INPUT NO CiS REC'D DOCKET NO:
x 40 50-263 DESCRIPTION:
ENCLOSURES:
Ltr furnishing supplemental information to cycle 2 startup report....
ACKNOWLEDGED DO NOT REMOVE PLANT NAME: Monticello e
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