ML19340B921

Safety Evaluation Supporting Amend 4 to License R-62 Re Temporary Waiver of Tech Specs to Permit Operation of Tests of 13-plate Fuel Assembly

ML19340B921
Person / Time
Site:	05000124
Issue date:	10/23/1980
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML19340B920	List: ML19340B919 ML19340B921 ML19340B922
References
NUDOCS 8011120571
Download: ML19340B921 (2)

Text

-

l

,.1 UNIT ED ST AT E :.

~

flUCLE AR hEGUL AT ORY CFJJ. HEC.

3 q

n. 4 m.nio:..O c :.

5 o.,

.*b,, :.. 3

\\.... *.,,[

SAFETY EVALUATION 3Y THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 4 TO FACILITY OPERATING LICENSE NO. R-62

/

VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY l

2 DOCKET NO. 50-124 Introduction By letter dated September 17, 1980, the Virginia Polytechnic Institute and State University (the licensee) requested an amendment to Appendix A of Facility Operating License No. R-62.

The requested amendment would grant a temporary waiver of the technical specifications to permit tests of one 13-plate element. The proposed testing would be carried out at low power (power level less than 1 KWt), the reactivity would not exceed the technical specification limit of ak/k of 0.6% ak/k and should not require more than t

30 days (1 to 31 December,1980). The objective of the specific tests involved is to measure the change in Keff when the 13-plate element is changed for a 12-plate element. These tests will provide data for preliminary analysis for operation at 500 KW, as the present configuration will have to be modified by adding an additional plate in each subassembly in order to operate at the higher power level.

Background

The current technical specifications for the reactor core (p. 4 No. 6.1.1) require that " standard fuel elements shall be of the flat-plate type with twelve plates to each element" and (p. 4, No. 6.1.3) " Maximum excess reactivity above cold clean critical shall be limited to 0.6% ak/k including positive reactivity from experiments." These measurements are classified as a "New Experiment." One or more dummy fuel plates must be substituted in the 12-plate elements as necessary to satisfy the excess reactivity requirement.

Evaluation To support the request for operation with one 13-plate subassembly, the applicant performed an approximate calculation of the reactivity change (based on thermal utilization only) associated with a loading consisting of 12 subassemblies of 13 plates each. This calculation indicates that the total reactivity worth change should be less than 0.4%.

This amendment will allow the determination of the reactivity addition due to one 13-plate Bon no 57/

i

. element at various positions in the core.

The licensee will remove the appropriate number of plates elsewhere to counteract the reactivity increase.

In addition, subcritical multiplication measurements will be performed during the approach to critical to insure that the limit on k(e.rcess) is not exceeded.

During the proposed measurements, the reactor will be operated at a power level less than 1 kwt, hence it is not expected that any other technical specifications related to the thermal quantities will be exceeded.

[

Conclusion We conclude that the proposed technical specifications waiver for the experiment with one 13-plate fuel subassembly is acceptable. We base this conclusion on the following-the ak/k (excess) will not be ev:eeded from that required by the technical specifications; i

s the power during the measurements will be less than about 1 KWt; the technical specification waiver is of limited duration and applicable only to these measurements; and subcritical multiplication measurements will be made during the approach to critical.

Dated :

October 23, 1980 v.

m--,

._.-