ML103130027

Letter from Kansas State University Providing Additional Information to a Request for an Upgrade to the Allowed 235U Inventory at the Kansas State University Triga Mk-II Nuclear Reactor Facility

ML103130027
Person / Time
Site:	Kansas State University
Issue date:	11/01/2010
From:	Geuther J Kansas State University
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML103130027 (2)

Text

1 November 2010 KSTATF.

1(STATE_

Department of Mechanical and Nuclear Engineering 3002 Rathbone Hall US Nuclear Regulatory Commission Manhattan, KS 66506-5205 Document Control Desk 785-532-5610 Fax: 785-532-7057 Washington, DC 20555-0001

.Re: License R-88, Docket 50-188 To Whom it May Concern:.

This letter provides additional information pertaining to a request for an upgrade to the allowed 235U inventory at the Kansas State University TRIGA Mk-II nuclear reactor facility. Specifically, this letter documents the storage geometry for the new fuel elements to be accepted under the amended license, and demonstrates the safety of this geometry.

On 29 July 2010, a letter was sent to the NRC requesting an increase in the allowable 2 5,U inventory at the KSU TRIGA reactor, in order to accept shipment of six new fuel elements.. In that.,.letter, it was -made clear that the -fuel would not be installed in the, core until additional-safety, analysis. work.: has-been6perf rmhed,.: However-no safety analysis' was given for holding the fuel on site prio# to installation in the core.

.~~' 7,7 The!-new'1fuel- elements ,will',be-,12%-uranium~loaded, .19.5%-enriched TRIGA elements from CERCA.., They will-be. l*adedftinto aluminum in-.poo7lfuel racks .onthe 'inside'of the reactor:tank.,., Tbese..racks are' desigied ýto' store Speit nuclea' fiel.* The6 storage *ra'cks' consist of.3.0.5 cm-wide,. 6.7 cm-deep .alunmiiium plates -with six holes, to accommodate six ,fuel elements., ,Most' of the. ful storage space is in sets oftw&. racks which arrange the fuel. in,-two rows 'of six elements,. butkeep the fuel at different 'axia elevationsto, reducez neutromc -coupling. . In -order, to test. the: criticality safety 'of these racks when holding fresh 12% fuel,. fourteen fuel elements were modeled in two rows of seven elements each, with no difference in elevation. The model was conservative, because it used fourteen fuel elemefits instead of twelve, and because the fuel racks were modeled at the same elevation (for.maximum neutronic coupling)',. The model was also conservative since-;it assumed that the racks would hold fourteen adjacent,,fresh 12%'1oided elemen"ts, while only six new elements are.,being procured,,'and,,these ill be-'storied next to' spent fuel or'vacant,:rack p'ositions 'in addition to other fresh eleihents. 'Theffiinal'inultiplicati6n factor was calculated ito be, 0.066907+- 0.00.025. . (The Ireported, uncertainty is from Monte. Carlo ,stiatistics oniy). ,1This isfai belowlthe critical multipiication.factorof 1.0, as expected, ,and shlows -that,the-fuelracks..c*ansafely- accom0 idateithe. fresh fueJ !uitivit is approved for insertion into the core. ".

The output ,were, checked,,by', a ,senior member. of the Reactor

-MCNPamodeland

,Safeguards Committee. withhexpertise. in MCN "*odeiingprior .to1the. issua c"'of this letter.

, / . . .'. ..

....'.:,AiJe"

I verify under penalty of perjury that the foregoing is true and correct.

Sincerely, Jeffrey A. Geuther, Manager KSU Nuclear Reactor Facility (785)532-6657 112 Ward Hall, Manhattan, KS 66506 cc: Cindy Montgomery, Project Manager