ML20077R677

Submits Results of Boric Acid Experiments on Known Core,Per Discussions W/Nrc & Univ Nuclear Safety Review Board.State Point Measurements Made Before & After Boric Acid Addition Agreed within Specified Reproducibility Errors

ML20077R677
Person / Time
Site:	Rensselaer Polytechnic Institute
Issue date:	08/08/1991
From:	Harris D RENSSELAER POLYTECHNIC INSTITUTE, TROY, NY
To:	Michaels T Office of Nuclear Reactor Regulation
Shared Package
ML20077R679	List: ML20077R677 ML20077R682
References
NUDOCS 9108230274
Download: ML20077R677 (2)

Text

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August 8,1991 Mr. Theodore S. Michaels U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, DC 20555

Dear Si :

Boric acid experiments have been carried out at the Rensselaer Polytechnic Institute (RPI) Reactor Critical Facility (RCF) on the "known" core in accord with earlier discussions with you and with the RPI Nuclear Safety Review Board (NSRB). This core, consisting of 4.81 w/o enriched U02 SPERT (FI) fuel at 0.585" pitch, was experimented on for 31/2 years prior .s July 1991. The objectives of these measurements (requested by NRC and NSRB) were (a) to demonstrate the boric acid handling equipment and procedures, and (b) to demonstrate the reproducibility of results during boric acid addition and removal.

Two ion exchange columns were received, inspected, placed, and tested successfully.

Modifications to the RCF included (1) an improved water filter system to prevent-

' impurities from clogging the ion exchange resins, (2) a pump to drain the reactor subtank, (3) piping connections for the ion exchangers, (4) city water inlet valve chained and locked shut and a circuit installed to provide a warning light in the control room if this valve were to be moved (feature requested by NSRU).

Procedures were developed for boric acid addition, removal, measurement of concentration, ensurance of uniformity, and avoidance of accidental dilution.

Reactor physics measurements with boric acid provide no new features, so their procedures are unchanged.

1 Reactor state point measurements were carried out as described in the accompanying paper (accepted for the upcoming San Francisco ANS meeting). State point measurements made before and after boric acid addition agreed within the p %the<,gcour e T M no. + c; , mr r i.A v r : e N ~ >

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specified reproducibility errors. No difficulties have been experienced with boric acid addition, removal, uniformity, and avoidance of accidental dilution. j Measurements of boric acid concentration by AllllCE and by us have yielded a f standard error of 10.7 ppm which has been rounded off to il ppm in the paper, i

I Sincerely, j l, iYn '

Dr. Donald R. Ilarris, Director  !

RPI Reactor Critical Facility l

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