ML19094A826
| ML19094A826 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 10/30/1975 |
| From: | Stallings C Virginia Electric & Power Co (VEPCO) |
| To: | Reid R, Rusche B Office of Nuclear Reactor Regulation |
| References | |
| Download: ML19094A826 (2) | |
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{{#Wiki_filter:'* Mr. Bernard.C. Rusche Director of Nuclear Reactor Regulation Attn: Mr. R. W. Reid, Chief Operating.Reactor Branch 4 U. S. Nuclear Regulatory Commission Washington, D *. C. 20555
Dear Mr. Rusche:
. scc.f,c-0.. /:-*- ,.\\.:I.I\\ \\,(\\8{\\t. .~ ,;,oc:O Doc_ket* Nos. 50-280, 50-281 .,*' *, / Lic~rrse Nos. DPR-32,DPR-37 \\ *~_:.. >_... ,,..:~ Ir_,.-.* SUPPLEMENTAL INFORMATION IN SUPPORT OF TECHNICAL-SPECIFICATION CHANGE NO. 33 (AMENDMENT TO OPERATING LICENSE DPR-32 AND DPR-37) .... *sURRY *POWER STATION*- UNITS *Nos~ 1 *AND 2
- In our letter of September 8, 1975, Serial No. 686, we indicated in Par_agraph 2 of Section 2. 2 of the Reload Safety Evaluation that "as indicated in WCAP 8362*,
the presence of. the two* 17x17 demonstration assemblies does not adversely affect.reactor performance.relative to an all 15xl5 assembly core. 11 Since the submittal of the above letter to you, our fuel supplier (\\*lest~nghcuse Electric Corporation) revised their predicticD.s on the nmcunt of rod bow that could be expected in the 17xl7 demonstration assemblies. In addition, Westinghouse presented the new data on rod bow, and its impact on the DNBR and power pealdng, to the U. S. Nuclear Regulatory Commission (NRC) on October 6, 1975. Based on the information provided in the October 6,* 1975 meeting, the effect of rod bow is expected*to be greater for the 17x17 assembly relative to the 15xl5 assembly. However, a speC:ific reanalysis of the effect of rod bow on the 17x17 demonstration assemblies irt the Surry units indicates that the conclusion of WCAP 8362 (that the two* 17x17 demonstration assemblies will not adversely affect the reactor performanc*e relative to an.all 15x15 assembly core) remains valid for both Surry units. The predicted DNBR penalty*due to the fuel rod bow at the end of
- three cycles of irradiation is slightly higher for the* 17xl 7 demonstration assembly than for*a 15x15 assembly in Surry.
However, the 17xl7 assembly still has approximately 7 percent greater DNB margin than the 15x15 assembly, even when conservatively assuming that the 17x17 assembly is the lead assembly. The greater DNB w.argin for the -17x17 demonstration assembly is based entirely on geometric considerations. There.fore, the* 17x17 demonstration assemblies in Surry 1 and 2 are not limiting from a DNBR standpoint.
- WCAP 8362 - "Irradiation of 17x17 Demonstration Assemblies in Surry Units No. 1 and 2, Cycle 2," July, 1974.
-{...... '. VIRGINIA ELECTRIC AND POWER COMPANY TO Mr. Bernard C. Rusche
- 2.
The local power peaki.ng penalty associated with the 17xl 7 demon-stration assembly due to bowed rods is a function of burnup and axial height. For the worst situation (i.e., second span and after three cycles of irr.adiation), the local power peaking penalty is approximately 2.6 percent greater for the 17x17 demonstration assembly relative to the 15x15 assemblies in Surry.
- However, the linear power density in the 17x17 demonstration assembly is significantly lower (approximately 30 percent if it is assumed to be the lead assembly based on geometric considerations) so that *the linear power density (with the peaking factor penalty included) is not limiting from a LOCA or overpower accident standpoint.
In addition, the effect of rod bowing on the periphery of the 17xl7 demonstration assemblies on power peaking in adjacent 15xl5 fuel assemblies was analyzed and found to be less limiting than other conditions in the core. It is concluded that the projected increased rod bow (relative to a 15xl5 assembly) associated with the 17x17 demonstration assemblies in both Surry Units No. 1 and 2 will not adversely affect the safety of the reactor relative to an all 15xl5 assembly core. Should you have any questions or comments, we would be m0st happy to meet with you on this matter at your earliest*convenience. cc: Mr. Norman C. Moseley, Director Office of Inspection and Enforcement Region II
- Very truly yours,/,,,*}.
~~c~~-~ A/ C. M. Sas O. ce President-Power Supply and Production Operations*}}