ML20133D077
| ML20133D077 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 08/02/1985 |
| From: | Reinaldo Rodriguez SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| RJR-85-358, NUDOCS 8508070219 | |
| Download: ML20133D077 (3) | |
Text
~ e suun SACRAMENTO MUNICIPAL UTILITY DISTRICT C 6201 S Street. P.O. Box 15830, Sacramento CA 95852-1830,1916) 452-3211 AN ELECTRIC SYSTEM SERVING THE HEART OF CALIFORNIA RJR 85-358 August 2, 1985 DIRECTOR OF NUCLEAR REACTOR REGULATION ATTENTION JOHN F STOLZ CHIEF OPERATING REACTORS BRANCH 4 U S NUCLEAR REGULATORY COMMISSION WASHINGTON D C 20555 DOCKET NO. 50-312 LICENSE NO. DPR-54 ANSWERS TO QUESTIONS ON PROPOSED AMENDMENT 126 In your letter of June 13, 1985 you requested additional information on SMUD's submittal of March 18, 1985.
The attachment to this letter contains the requested information.
Should you have any questions concerning this proposal, please contact Mr
.W lombo at Rancho Seco Nuclear Generating Station.
N R. J. RODRIGUEZ ASSISTANT GENERAL MANAGER, NUCLEAR Attachment Sworn to and subscribed before me this 2nd day of August, 1985.
(? ' LELH Cd C)
~
Notary Public emmmma::mmm:nemmmonmum::nnumiimaxmmunmurg N
PATRICIA K. GEISLER R
" 4dyd Norun reitu<:--- cAi.tFoltNI A 4,f ? :
nuv;i u. on icr is g
j SAcit.u!Exto cot'NTY g 3 f/y Commissica Expires February 16,19886 t
o mmuinmmnu~ "i '"~ "mn' "w"a "ennian"40
'i t Rygeorhbf Q P
\\
n Pg
'Qunstion 1:
Your submittal of March 18, 1985 states that a baron concentration of 1974 ppm will "... sustain a reactivity condition of keff = 0.95 or less with all control rods removed from the core." (underlining added).
Neither the Rancho Seco Updated Safety Analysis Report (containing nuclear data for Cycle 6) or the Reload Report for Cycle 7, however, provide a basis for confirming the f
correctness of this concentration. Therefore, please provide a copy of the analysis that resulted in this estimate.
If the analysis utilized information
~
from reference documents, please provide applicable extracts from the referen-ces.
Response
The following calculation is the basis for the Rancho Seco Cycle 7 Technical Specification requirement of 1974 ppmb to sustain a reactivity of keff.= 0.95 or less with all control rods removed from the core.
Refueling Baron Concentration (RBC) was calculated with a 1-zone (coarse mesh)
P0Q model, which has extensive fitted cross sections at cold conditions and is B&W's standard model for these calculations.
Because physics calculations for the reload licensing of cycle 7 were performed with the N000LE code, appro-priate normali tion of 1-zone P00 to N000LE calculated reactivity was made.
This norma' on includes the reactivity effects of the axial blanket which was modelen iOODLE, and maintains consistency with all of the other reported phys cs data for cycle 7.
Because the RBC is to be specified with all control rods removed from the core, the base 1-zone case used for the calculation was run with all rods withdrawn, including Bank 8.
The RBC was then calculated as folicws:
RBC = BC + IBW(o + Model a + Criticals + NUAB + 4R + ZR + SDR) where RBC = The Re' fueling Baron Concentration for keff = 0.95 with all control rods removed from the core.
BC = The baron concentration of the base 1-zone P00 case used to calculate RBC.
(BC = 2000 ppmb)
IBW = The cold inverse baron worth in the boron concentration range of the RBC, calculated with 1-zone P0Q.
(IBW = 89.2 ppmb/% ak/k) o = The reactivity of the base 1-zone PDQ case at 2000 ppmb with all-rods-out.
(p = -5.55% ak/k)
Model a = The adjustment for the reactivity difference between a N000LE case with axial blanket modeling and an equivalent 1-zone P00 case without axial blanket modeling.
(Model a =
.449% ak/k)
- =
w e 64* * *
.=
,..w m
J
( _.
o Criticals = The constant-valued standard B&W model correction which accounts for observed biases between PDQ calculations and measured critical experiment data.
(Criticals = +.4% ak/k)
NUAB = A standard B&W generic model correction to reactivities calculated with 2-0 PDQ, which accounts for non-uniform axial burnup effects not seen in the 2-D calculations.
(NUAB =
.69%
ak/k for 80C-7) 4R = The standard generic flux redistribution model correction for 2-D calculations to account for the reactivity worth of axial flux shifts.
(4R =.54% ak/k for BOC-7 refueling conditions)
ZR = The reactivity worth of the Zirc grid relative to Inconel grids which are the basis for the fitted PDQ cross sections.
(ZR =.2%
ak/k)
SDR = The Tech Spec shutdown requirement of a keff of.95, converted to units of reactivity.
(SDR = 5.26% ak/k)
This analysis results in a refueling boron concentration of:
RBC = 2000 + 89.2(-5.55
.449 +.4
.69 +.54 +.2 + 5.26)
= 1974 ppmb Ouestion 2:
if your review of *.he information needed for this submittal should reveal an error in the analysis that would increase the required concentration, please provide an appropriate revis'.on to your request and to LER 85-03.
Response
The calculation presented in the response to Quest..n'l has been reviewed and found correct.
O 9
9
\\
-