ML20098E158
| ML20098E158 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 05/28/1992 |
| From: | Shelton D CENTERIOR ENERGY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 2043, IEIN-91-066, IEIN-91-66, TAC-M83724, NUDOCS 9206020002 | |
| Download: ML20098E158 (3) | |
Text
,.
f-ENTEMOR ENERGY Donald C. Shelton 300 Madison Avenue Vee Presidenblulear ioledo, OH 436520001 -
Dam resse (419)249 2300 Docket Number 50-346 License Number UPF-3 Serial Number 2043 May 28, 19"2 United States Nuclear Regulatory Commission Document Control Desk Vashington, DC 20555-
Subject:
Davis-Besse Nuclear Power Station Resolution of Nuclear Regulatory Commission Information Notice 91-66 Regarding Spent Fuel Pool Criticality Analysis Gentlement The subject Nuclear Regulatory Commission (NRC) =Information l
Notice (IH) 91-66 (lag Number 1-2560)-identified that erroneous data exists in the " Nuclear Safety Guide, TID 7016, Revision-2" (NUREG/CR-0095, ORNL/NUREG/CSD-6/1978).
Toledo Edison's reviev.has determined that_this error is not applicable'to the Davis-Besse Nuclear Power Station (DBNPS).
IN 91-66 also identified that a temperature depender discrepancy exists between KENO-V.a and CASH 0-3 calculations for-lignt-vater reactor fuel assemblies in a storage configuration.
s Toledo. Edison's review indicates-that this error does not affect the criticality analysis performed for the DBNPS new fuel' storage faClity, however it does affect the criticality analysis p^rformed.for the DBNPS spent fuel pool (SFP).-
The criticality analysis performed by Babcock & Vilcox Fuel Company (BVFC) for fuel storage in the DBNPS SFP utilized the KEN 0 computer code. :. Toledo Edison performed a review of~the' analyses based on the-information provided in.IN 91-66 and found that the. temperature dependence.of k-effective vas not correctly determined and that the final values of k-efiective vere,.therefore, erroneously-lov. BVFC.
-intended to perfora its KENO spent fuel rack calculations.at the va*.er temperature which produced the highest value of k-effective.
Due to
.the discrepancy described in IN 91-66, this. temperature was erroneously.
-determined to be 90*F.
Toledo Bdison used the CASH 0-3 code:to determine the magnitude of the error.in'the values of k--effective calculated-by B&W us_ing KENO.
CASH 0-3'vas the same code that was used to determine the errors in~the-KENO cross section. sets noted in IN 91-66.- Also,'CASM0-3 has'been-pa o 9 O
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Docket Numbar 50-346 License Numbar NPF-3 Serial Number 2043 Page 2 extensively benchmarked by Toledo Edison against cold, critical experiments, and has produced excellent results.
CASH 0-3 predicts a continuous increase in k-cffective with water temperatu.3, which is consistent with calculations referred to in IN 91-66.
It is inferred that it is more conservative to assume a higher vater temperature.
Therefore, Toledo Edison determined the reactivity difference between 90'F and the maximum possible temperatures that could exist in the SFP.
A temperature of 240'F vas assumed, which is approximately the highest saturation temperature that could exist at the depth of the spent fuel racks. This value exceeds the design basis maximum temperature for the SFP (assuming no heat removal capability), which has been calculated to be 206'F.
The resulting reactivity difference, or " temperature penalty", using a SFP temperature of 24W 7, was determined to be
+0.00650 &.
As documented in the NRC Safety Evaluation dated April 13, 1989, relating to License Amendment Number 130 to the DBNPS Operating License, the SFP criticality analyses included a dropped fuel assembly lying horizontally on top of the vertical stored fuel assemblies.
In addition, the spent fuel pool vas assumed-to be simultaneously infinitely diluted (i.e., no soluble boron).
Having to assume two simultaneous accidents (dilution accident and dropped assembly-accident) was beyond regulatory requirements. Therefore, the dilution accident, which is more severe than the dropped assembly accident, should be considered separately.
The magnitude of the reactivity penalty associated with the dropped assembly accident was 0.01319 & i 0.00595 &, with the uncertainty being due to the statistical (Monte Carlo) methodology used to calculate this penalty.
Since the uncertainties were always applied in a conservative fashion by statistically combining them and adding the result to the base k-effective to obtain the final k-effective, the net penalty associated with the dropped fuel assembly accident amounted to about 0,016 &.
The temperature penalty magnitude (0.00650 &) is less than half of the magnitude of the dropped assembly penalty (0.016 &). Therefore, removal of the dropped fuel assembly accident penalty-vill more than offset the temperature penalty that must be. applied'to compensate for the "ENO eross section error.
Toledo Edison concludes that the DBNPS SFP fuel storage design remains safe and that the design continues to.
meet all acceptance criteria.
<j l
_ -. _ ~.
Docket Numb 3r 50-346 License Number NPF-3 a
Serial Number 2043 Page 3 Toledo Edison requests your written concurrence by November 2, 1992, that the basis of your previous approval of License Amendment Number 130 remains valid.
Should further information be required, please contact Mr. R. V. Schrauder, Hanager - Nuclear Licensing, at (419) 249-2366.
Very truly yours,
/Vv HKL/vab Attaci.ments cc A. B. Davis, Regional Administrator, NRC Region III J. B. Hopkins, NRC/NRR DB-1 Senior Project Manager V. Levis, NRC Senior Resident Inspector J. R. Villiams, Chief of Staff, Ohio Emergency Management Agency, State of Ohio (NRC Liaison)
Utility Radiological Safety Board l
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