ML20085D225

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Change Rept 8 to Application for Amend to License DPR-4, Changing Test Procedure for Approach to Chemical Shim Control Operation as Described in Safeguards Rept
ML20085D225
Person / Time
Site: Saxton File:GPU Nuclear icon.png
Issue date: 05/16/1963
From: Neidig R
SAXTON NUCLEAR EXPERIMENTAL CORP.
To:
Shared Package
ML20083L048 List: ... further results
References
FOIA-91-17 3576, NUDOCS 9110150349
Download: ML20085D225 (3)
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l SAXTON NUCLEAR EXPERIMENTAL CORPORATION DOCKET NJ. 50-146 LICENSE DPR-h l

CHANGE PIPORT #8 l

1. Applicant hereby submits Change Report /3 in compliance with paragraph 3(B)(1) of Licensc DPR-h. This change pertains to the procedure to be used in the approach to full chemical shim control as described on pages 13 and 22 of the Safe;;uards Rcport for Phase 1 of the Saxton Nuclear Experimental Corporation Five-Year Research and Development Program. Pages 13 and 22, revised as of May 16, 1963, are attached to this Change Report #8.

SAXTON NUCLEAR EXPERIMENTAL CORPORATION t

By /s/ R. E. Neidig President i Attest:

! /s/ R. E. Sypher l Secretary i

Sworn and subscribed to before me this 16th day of May 1963 c7 I=/ 4 /c/ Martin A. Kohr (SEA Notary Public kg/ ,'[B

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May 16, 1963 Docket No. 50-lh6 DPR-h Change Report #6

1. Description of En g Operating pu:edures described belcw for approaching full chemical shim operction have been revised from those described on pages 13 and 22 of the Safeguards heport for Phase 1 cf the Saxton !!uclear F.xperim .tal Corporation Five-Year Research and Development Program as amended by Su.>plement Mc.1 to that report. Pages 13 and 22, revised as of May 16, 1963, are attt.ched to reflect this change.
2. Purpose of Change Close examination of the previous technique described on pages 13 and 22 has indicated that the accumulated uncertainties in tracking reactivity

$ when both power level and boron concentration are being changed can be such that a clear demonstration is not possible. The new procedures have been developed to avoid this difficulty. In addition, since the Safeguards Report for the chemical shin experiment was written, the results of Yankee's second power test at moderate boron concentrations have become available. The satisfactory outcome of those tests reduces the need for further efforts at low boron concentrations. Thus this change is being made in order to:

(a) Frovide a demonstration of chemical shin witn reduced uncertainties.

(b) Minimize the duplication of experiments which have been performed at other plants.

3 Operating Procedure Preferred Procedure - With the reactor operating at zero power, approximately 1100 ppm boron will be added to the main coolant. The reactor power level will then be increased to approximately 15 MWt over a period of approximately two hours and maintained at this level during Xenon buildup.

The reactivity changes during this period will be compared with t, hose which occur under the same conditions without boron in the main coolant. The reduced power level was chosen to eliminate any possibility of nucleateboiling which could complicate initial interpretation. If it is determined by experimental measurements that a higher power level can be obtained without nucleate boiling then that power level may be used.

Alternate Procedure - As an alternate procedure, the reactor may be brought up to approximately l$ I&t with no boron 1.n the main coolant. After equilibrium conditions are reached, stepwise additions of boric acid would be made. Each addition would be compensated for by allowing the temperature to reduce while holding power level as steady as practical. After measurements have been completed, the original coolant temperature would be restored by rod motion. This procedure would then be repeated until full chemical shim control boron concentration is reached.

h. Conclusion It is our conclusion that this change does not involve a change in the  ;

Technical Speci.fications or any unreviewed safety question and that the health l and safety of the public will not be endangered by this change.

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I 13 95% theoretical density is the equivalent of gl = 2h kw/ft for T3 = 11000F and 93% theoretical density. The proposed operation at 16 kw/ft is thus well '

belcw the power level at which center melting occurs or where there is any known danage to the fuel rods.

Additional information has very recently become available from a series of in pile capsule irradiations perforned for the Carolinas VriCinia Nuclear Power Associates Research and Development Program.25,26,27 Six capaules, each containing three UO2 fuel rods, have been irradiated at +ower ranging from12to2hkw/ft. (Power levels estimated to be within - 5)*

The rods have had diametral gaps between fuel and clad of 6 to 25 mih, and have been backfilled with both helium and argon. Center melting was not observed until 2h kw/f t was reached. In all cases the rods were undamaged and were not distorted in any way. #cetioning of the fuel rods showed the UO2 to be in a satisfactory condition.

On the basir of the foregoing information, it is concluded that there is adequate information available to justify as conservative the increase of the maximum specific power of the entire core to lb.1 kw/ft and the specific power of special test assemblies to 16 kw/f t.

IV. EXPERIMENTAL PROGRAM A. Test Prorram During the startup test program careful measurements will be made of the core reactivity. Measurements of the all-rods-out boron concentration vill be made (i) prior to power operation, (ii) after enough power operation for the equilibrium Sm poisoning to be attained, and (iii) after several weeks of power cperation. This latter measurement will be just prior to the beginning of chemical shim operation. During the initial power operation a large number of measurements of rod worth, temperature coefficient and pcuer coefficient will be made. By these techniques it is expected that a good understanding of the reactivity behavior of the reactor will be attained.

The first portion of the chemical shim program .till consist of operation at approximately 15 Mdt or a power level at which nucleate boiling does not occur. After full chemical shim at non-nucleate boiling conditions has been completed, chemical shim tests at higher power levels and nucleate boiling will be conducted.

l During this experiment, a continuous record of reactivity will be kept by means of at-power measurements. Power operation will be allowed to continue so long as the at-power reactivity measurements show no unexplained loss above the allowable. The allowable unexplained reactivity loss will be set on the basis of that amount of reactivity which if suddently released )

would exceed the accident criteria as described in Section V - Accident Analysis. Present conserystive calculations indicate that for a maximum j fuel specific power of 12 kw/ft (corresponding to 20 MW) a 0.5% Ak release l is tolerable. The actual limit will be set by revised calculations using )

l the reactor characteristics determined during the startup experiments. R J

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l Revised: May 16, 1963 mn Rwr+ 4

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