ML18127B136
| ML18127B136 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 11/18/1976 |
| From: | Robert E. Uhrig Florida Power & Light Co |
| To: | Stello V Office of Nuclear Reactor Regulation |
| References | |
| CEN-38(f)-P, Rev. 1, L-76-401 | |
| Download: ML18127B136 (10) | |
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NRC DISTRIBUTION FoB Mr Stello V.O. NUCLEAA AEOVLATOBVCOM~I'SION PARl 50 DOCI(ET MATERIAL F ROh1:
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1976
'v Office of Nuclear Reactor Regulation Attn:
Victor Stello, Jr.~ Director Division of Op'crating Reactors U. S. Nuclear Regulatory Comnd.ssion Nashington, D. C. 20555
Dear Nr. Stello:
4g Re:
St. Iucie Unit No.
1
,Docket No. 50-335
~ Repair Report CEN-38(f}-P, Rev.. 1
- ,.- Su 3.event.al Information This letter suppleraents the information contained in. the subject report.
It also serves to docuIaent the resu1ts of recent discussions with members of your staff.
Lv L
Section V of the subject report indicates that the startup test program include measurements of rod vorths of CEA Croup 1 and shutdown group 8 only if the measurements of CEA groups 7,6,5,4,3, and 2 differ from predictions by a significant variation.
Rod worm's measurements are to be IxIade with the following two objectives in mind:
1)
To verify adequate shutdown margin as cRefined in Section 1.13 of the Technical Specifications.
2)
To corapare to design calculations.
Measurements
~ are generally expected to agree with design values "ithin <10% or 0.1% h~/Ic whichever is larger.
To satisfy these requirements, the following rod worth measurements shall be performed during the startup phys5.cs tests.
CEA groups 7,6,5,4,3,2 will be measurect and compared to design calculations as described in item 2) above.
If these measurements
{7>>2) fail the above acceptance criteria, groups 1 and 8 shall also be measured.
Xf the um of groups 7 through 1 and shutdown groUp B differ by raore than 10$
from the design values, then the design calculations shall be reviewed.
'F4
To Re Victor Stello, Jr.,
NRC St. Lucie Unit Ão. l Docket Mo. 50-335 Supplemental Information Re air Re ort CEH-3S(f)-P, Rev.
November 18, 1976 Page 2-Table l contains the design reactivity parameters associated with the calculation af shutdown margin.
Xt is seen that measurement of CEA groups 7-2 represents more than 85%
'(5%
hx/x less XOS for uricertainty +4.5% hx/K) of the rod worth required to maintain shutdown margin (5.05% hej'x).
Therefore~
. adequate margin auld be ensured unlesi predictions of the worth of the remaining rods vere in error by more than 80%.
However, the revised design calculations demonstrate that the rod vorths are essentia1ly unchanged from beginning of life (BOL) and the SOL measurenients of all rods (7-1, AaB) are in excellent agreement with the original predictions.
The following additional at power monitoring is to be performed if the excore mode described in paragraph 4.2.X.2 of the 5'ech-nical Specifications is used and the core bur@up is 3.ess than 10 GHD/RTU.
This core burnup ensures that, in the unlikely event of redistribution and loss of the remaining boron in a fashion similar to that experienced with the origina3. shims, the resultant axial and radial power peaks would be within the original design criteria.
This additional monitoring will be suHicient to ensure that if the anomaly Mere to reoccur, it would be detected prior to original design criteria being exceeded-l.
The axial peaking factor is to be monitored in the maximum number of bundles possib3.e via fixed incore Rh detectors.
The surveillance 'period shill be sufficient to ensure that the axial peak increases less than 3% b tween measurements based on the average growth rate from the nest recent measurements but not to exceed 7 operatin g days.
A 3% per day growth rate in the axial peak shall be assuieed until aieasurements are available.
All measured growth rates shall be doubled to account, for ineasure-ment and projection uncertainties.
2.
Core power maps are to be taken weekly (7 operating pays}
and compared with predicted distributions.
Additional aenitoring using the traversing encore probes has been evaluated Design calculations and measurements with incore movable fission detectors demonstrate that boron loss and redistribution as experienced in the original pins do not cause local power perturbations that can be detected at the
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To Re:
Victor Stello, 3r.,
HRC St. Lucie Unit No. l Docket No. 50-335 Supa1eraental Information Re air Re rt CEN-38 (f)-P, Rev.
1 November 18, 1976 Page instrument thimble (both the Rh and fission detector thimbles are located in the center guide tube).
Se have concluded, therefore, that additional monitoring using the traversing in-come probes wouM not be appropriate.
Very truly yours, Robert E-Uhxig Vice Pzcsile?lt BEUjHLRjhlc Attachsnent cc:
harlan C-Nuseley, Region IX Robert Lovenstein>
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TABEK DESIGN BEACTXVITE PARhMBFFRS SHUTDOfM HARGXN CAXCURATIOHS Po..e De Fe ct (DoppIer + Noderator)
Transient Xenon CRA 8ite 8 Boron Deadband PjL CRA E'ffeats Shutdown kwrgS.n 8 Accident Analysis A1lowance Tota 1 Reactivity Change (unrodde8 )
2 ~ 3
~I 0 2 0 ~ 0 2 ~ 45
Stuck Rod 5 ~ 0 Mp 1. I 4 ~ 1 2 ~ 7 Rodworth All Rods - Stuck Rod Measurement, Uncertainty Avai1ahle Rodworth Iess Uncertainty 6
8 M,p Rodaorth Excess of Shutdown Hargin Ress Yeasurement Uncertainty
>Pre Iininary calcu lations - Revised calcuIations for
'dividua 1 bank w'orths are 4 0% eorap 3.ate.
These numbers are projected from the original values usIng the smal 3.
differences seen in the revised values.
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