ML20215M432

Forwards Request for Addl Info Re 860912 Application for Amend to Ol,Authorizing Use of Newly Developed Extended Life Aluminide Fuel Element Containing Higher Densities of U & Burnable Poison

ML20215M432
Person / Time
Site:	University of Missouri-Columbia
Issue date:	05/07/1987
From:	Rozier Carter Office of Nuclear Reactor Regulation
To:	Brugger R MISSOURI, UNIV. OF, COLUMBIA, MO
References
NUDOCS 8705130235
Download: ML20215M432 (5)

Text

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May 7, 1987 Docket No. 50-186 DISTRIBUTION, ,

ptetetTUe/ FSchroeder NRC'8 Toial PDRs HBerkow OGC-Bethesda EHylton Dr. Robert M. Brugger, Director RCarter EJordon Research Reactor Facility JPartlow ACRS(10)

University of Missouri p PDSNP Reading Columbia, Missouri 65211

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION We are continuing our review of your application dated September 12, 1986 for an amendment to the operating license for your research reactor. This amendment would authorize the use in your reactor of a newly developed extended life aluminide fuel (ELAF) element containing higher densities.

of uranium and a burnable poison.

During this review, several questions have arisen for which we require additional information in order for us to complete our evaluation. You are requested to provide written responses to the enclosed questions no later than

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t ninety days from the date of this letter. Following receipt of this information we will continue our review.

If you have any questions concerning this request, please contact me at (301)492-8206.

The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OMB clearance is not required

'under P.L.96-511.

Sincerely.

A 4

Original signed by Robert E. Carter, Project Manager Standardization and Non-Power Reactor Project Directorate Division of Reactor Projects III, IV, 3

V and Special Projects

Enclosure:

As stated cc w/ enclosure:

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%,,,,,# May 7, 1987 Docket No. 50-186 Dr. Robert M. Brugger, Director Research Reactor facility University of Missouri Columbia, Missouri 65211

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION We are continuing our review of your application dated September 12, 1986 for an amendment to the operating license for your research reactor. This amen 6nent would authorize the use in your reactor of a newly developed exteno3d life aluminide fuel (ELAF) element containing higher densities of ur6aium and a burnable poison.

During this review, several questions have arisen for which we require Odditional information in order for us to complete our evaluation. You are r? quested to provide written responses to the enclosed questions no later than ninety days from the date of this letter. Following receipt of this information we will continue our review.

If you have any questions concerning this request, please contact me at (301) 492-8206.

The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore OMB clearance is not required under P.L.96-511.

Sincerely.

Robert E. Carter, Project Manager Standardization and Non-Power Reactor Project Directorate E* vision of Reactor Projects III, IV, Y and Special Projects

Enclosure:

As stated cc w/ enclosure:

See next page

j University of Missouri Docket No. 50-186 at Columbia cc: University of Missouri Associate Director Research Reactor Facility Columbia, Missouri 65201 A-95 Coordinator Division of Planning Office of Administration P. O. Box 809, State Capitol Bldg.

Jefferson City, Missouri 65101 Attorney General Supreme Court Building Jefferson City, Missouri 65101 1

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3 TECHNICAL REVIEW QUESTIONS  !

tm!VERSITY OF MISSOURI EXTENDED LIFE FUEL REVIEW l

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1. The fuel plate oxide thickness is a function of operating time. What '

I is the projected oxide thickness for the increased operating time?

2. Reported results indicate that the peak power density will be on inner fuel plates for the new elements. What are the power profiles on the hot fuel plates? Is the 1.04 azimuthal peaking factor still valid?

3. The increased element operating time above your current practice will result in increased likelihood of fuel plate corrosion and in pit depth. What is the projected primary coolant radioactivity level if a pit results in release of fission products, and what are the projected consequences to the public?

4. Projected oxide thickness exceeds the minimum that has been shown to result in spontaneous spallation. What data is available for validation of oxide thickness projections? What are the consequences to fuel clad as a result of spallation, e.g., subsurface voids? What is the impact to safety limits as a result of changes in heat transfer from the spallation zone? Is the oxidation rate accelerated on the spallation zone such that multiple spallation at that location is more likely? What would be the potential consequences to the public?

5. The predicted increased oxide thickness above that for current operating conditions will result in changes to the reactor operating characteristics. What are the changes in fuel plate (steady state) operating temperatures? What are the changes in reactor response to reactivity perturbations as a result of increased oxide thickness on the fuel plates?

6. were TheGroup3andGroup4controlrodconstants(crosssections)dworths adjusted to force control blade worth agreement with measure in the present core. The proposed core is expected to have a harder neutron spectrum, resulting in changes to the core leakage and leakage energy spectrum. What evaluations have been completed to demonstrate that the cross sections for the current core are sufficiently valid for the proposed cores that control blade worths and reactivity conditions will be consistent with Technical Specifications?

7. The nuclear peaking for all fuel combinations was evaluated with a water-filled flux trap. Maximum peaking does not occur on Plate 1 for the proposed elements. What are the peaking factors in a core com)osed of the proposed fuel with experiments allowed within tecinical specification limits?

8. The cross sections for the reactor materials are dependent on temperature and fuel burnus. How were corrections made to the cross sections used for the bencimark to represent spectral changes and different operating temperatures as a consequence of 10 MW operation and increased oxide thickness? Were calculations for " mixed" cores performed with cross sections representative of burnup? What are the cross section sensitivities to temperature and fuel and boron depletion, and what are the effects on calculated control blade worths and power peaking factors? Are these consistent with your Technical Specifications?

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9. The proposed core is expected to have neutron spectra different from the current core. What are the expected changes in core temperature and voiding reactivity coefficients? What impact will these changes have on conditions and postulated accident scenarios?

10. The proposed fuel elements will be loaded with a variable and higher uranium density and some plates have boron added. The hot spot is on a different plate and the azimuthal peaking is higher. What calculations have been performed to demonstrate that the hot channel factors used for analysis of the safety limits are applicable to the proposed core?

11. The proposed core has different nuclear characteristics, i.e., power peaking, fuel temperature, oxide thickness, neutron spectra. What is the reactor response to accident conditions with the proposed core that have not been analyzed and discussed previously?

12. The prososed elements will operate with peak power on a different plate t1at has an increased fuel loading. What effect does this have on the DBA environmental considerations related to accident scenarios?

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