ML20059L708
| ML20059L708 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 11/10/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20059L706 | List: |
| References | |
| NUDOCS 9311170305 | |
| Download: ML20059L708 (2) | |
Text
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UMTED STATES k.]a a'
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NUCLEAR REGULATORY COMMISSION
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WASHINGTON, D.C. 20555-0001
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ENCLOSURE SAFETY EVALUATION BY THE OFFICE OF NUCliAR REACTOR REGULATION RELATING TO LOW POWER PHYSICS TESTING PROGRAM OMAHA PUBLIC POWER DISTRICT FORT CALHOUN STATION DOCKET NO. 50-285
1.0 INTRODUCTION
By letter dated October 1,1993, Omaha Public Power District (OPPD) requested changes to the Low Power Physics Testing (LPPT) Program for Fort Calhoun Station (FCS).
The proposed change is to eliminate the pseudo ejection symmetry checks and replace them with a low power flux map prior to 30 percent power.
The LPPT Program was originally proposed in Cycle 6; a revision to the program was proposed and approved for Cycle 10.
The current program requires the following tests be performed after initial criticali' for each fuel cycle:
- 1) Critical Baron Concentration Measuremcnts; 2)
Isoths al Temperature Coefficient Measurements; 3)
Regui and Shutdown Control Element Assembly (CEA) Group Worth Mea ts; and 4)
Pseudo L n.dion Grcup 4 Symmetry Checks.
OPPD performed a comprehensive review of the LPPT Program in order to optimize test performance and minimize testing time. Their review concluded that the pseudo ejection Group 4 symmetry checks should be eliminated and the flux map should replace it.
2.0 EVALUATION When the LPPT Program was initially proposed it was considered important to have a flux symmetry test before going above 5 percent power in order to verify that the core was symmetric as designed. Since it was impossible to obtain meaningful results from a flux map at such a low power, the pseudo ejection symmetry check test was used as a flux symmetry test. The results of the pseudo ejection symmetry checks are not as useful as those of a flux inap.
Since initial approval of the program it has been recognized that no safety limits world be exce
.-! with an asymmetric core as long as the power level was not above 30-35 ;. cent. Thus it would be better to obtain more i
meaningful results by using a flux map at a slightly higher power level.
931117o305 931sto DR ADOCK 05000285 i
The flux symmetry test is better performed by using the flux distribution l
method. This method requires incore flux detector responses to be recorded for various azimuthal locations which are well distributed throughout the core. These responses are then converted to flux values and the flux map is reviewed for symmetry throughout the core. OPPD has the capability of perform the flux symmetry test prior to reaching 30 percent power through the use of l
the incore monitoring system.
The data obtained will be more meaningful than that obtained by the symmetry check at zero power. Use of the low power map will be an improvement over the symmetry checks and thus is an acceptable change.
3.0 CONCLUSION
S The staff has reviewed the information submitted by Omaha Public Power District and based on the above information has concluded that the proposed change to the Low Power Physics Testing Program is acceptable.
4.0 REFERENCES
1.
W. G. Gates, Omaha Public Power District to NRC dated October 1, 1993.
Principal Contributor:
M. Chatterton Date: November 10, 1993 I
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