ML20128E007

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Discusses Insp of Inverted Poison Tubes in Plant,Per Util 740510 Transmittal of Results of Eddy Current Insp
ML20128E007
Person / Time
Site: Monticello Xcel Energy icon.png
Issue date: 05/29/1974
From: Sapir J
US ATOMIC ENERGY COMMISSION (AEC)
To: Ziemann D
US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 9212070446
Download: ML20128E007 (1)


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Piles ( ekst No. 50-263) 1111 0 s . L. Eismenn, Chief, OR3 f2, L INSPBCTION OF INVERTED POISON TURES IN THE MONTICELLD MUQ.RAR CENERATING PLANT (NORTHERN STATES POWER COMPANY)

In a letter dated May 10, 1974 Northern States Power Company (NSP) transmittad the results of their eddy current inspection for inverted poison tubes and an analysis of the potential effect of 34C compaction in the inverted tubes remaining in the Monticello Nuclear Generating i Plant.

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 potential shutdova margin loss assuming full 54C settling in these 19 inverted tubes was calculated to be 0.04% Ak. NSP plans, as we have directed, to add this_value to technical specification shutdown margin require-monts as long as these blades remain in the core. NSF concluded, and we agree, that the potential effects of B4 C settling on the rod drop accident and pressurisation transients are negligible.

We have reviewed the NSP submittal and concluded that they have adhered to the requirements specified in our letter to them dated April 1,1974,

and subsequent operation with 19 inverted poison tubes does not present any significant safety problems.

Joseph L. Sapir Operating Reactors Branch f 2 Directorate of Licensing cca L. O. Mayer, NSP AEC PDR Local PDR Disj:ribution K. R. Go11er, L:0R A 6cket File T. J. Carter, L:0R Branch Reading k0 (3) ORB #2 File o0c-D. L. Ziemann, L 0RB #2 J. J. Shea, L 0RB #2 .

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