ML20008E016
| ML20008E016 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 09/26/1980 |
| From: | Furr B CAROLINA POWER & LIGHT CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| IEB-79-26, NO-80-1392, NUDOCS 8010240067 | |
| Download: ML20008E016 (3) | |
Text
I Carolina Power & Light Company l $,
i
.siA September 26, 1980
'f] ((I l; P I: 23 FILE: NC-3513 (B)
SERIAL: NO-80-1392 Mr. James P. O'Reilly, Director U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 3100 Atlanta, GA 30303 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO. 1 LICENSE NO. DPR-71~
DOCKET NO 50-32 V SUPPLEMENTAL RESPONSE T BUL'ETIN 79-26
Dear Mr. O'Reilly:
In accordance with our response ti IE Bulletin 79-26 dated January 3,1980, Carolina Power & Ligt t Company (CP&L) provides the following supplemental response addressing Item 3 of the subject bulletin for the Brunswick Plant.
Item 3 of the subject bulletin requested that at the next cold shutdown or refueling outage, CP&L conduct shutdown margin tests to verify that full withdrawal of any control blades from the cold xenon-free core would not result in criticality. Also, it was requested that we verify compliance with the shutdown margin require-ment in a manner that accommodates the boron loss phenomenon.
In accordance with the Technical Specifications and Item 3 of the bulletin, shutdown margin (SDM) testing was conducted prior to the initia1'startup of the Unit 1 reactor which verified that the full withdrawal of any control rod did not result in criticality.
In order to verify compliance with the SDM Technical Specification, two control rods were withdrawn from the cold, xenon-free core to i
insert the required amount of reactivity. The two rods chosen for i
this test are listed in General Electric's Cycle Management Report for Brunswick 1, Cycle 3.
Rod 06-31 was analytically determined to be the control rod with the highest reactivity worth at the beginning of cycle, and rod 10-35 was diagonally adjacent to 06-31.
a.
e - '
'. P adA %
,-'qe..
411 Fayetteville Street
- P. O. Box 1551
- Raleigh, N. C. 27602
' W ML COPY
= _. 3rn w-
_a-
-_..._... ~ _. - - -., -.. - -. -. - - - ~.
)
m Mr. Jcmes.P. O'Railly Saptsmb2r 26,1980 I
The calculation of the required shutdown margin for the SDM demonstration was as follows:
Required SDM = 0.0038 + R - [(T - 68) x TC)
Where: 0.0038 = Ak required by Technical Specifications R = Difference between maximum k,gg during the cycle and k,ff at the beginning of cycle.
T = Primary coolant temperature ( F)
TC = Temperature coefficient (Ak/k F)
From the GE cycle management report:
R = 0.0091
-5 TC = -4.0 x 10 Ak/k F At the time of the shutdown margin test:
T = 96 F Based on these parameters, the required shutdown margin was calculated to be 0.01402.
In order to insert this amount of reactivity, rod 06-31 was withdrawn fully, and rod 10-35 was withdrawn to position
- 36. The nuclear instrumentation was monitored after this withdrawal, and it was verified that the reactor did not go critical.
At the completion of the previous operating cycle, both of the control rods used in the SDM demonstratica, as well as all other rods in the Unit 1 core had very little exposure. The control rod with the greatest exposure had a B-10 depletion correrpanding to 14.83 percent and the control rod used for the SDM test had a B-10 depletion of approximately 5.8 percent.
Section 12 of General Electric's Topical Report NEDO-24232,
" Control Blade Lifetime Evaluation Accounting for Potential Loss of B C," recommends that additional SDM be demonstrated if any control g
blade in the core has a B-10 depletion of 34 percent, or is expected to have this depletion prior to the next refueling outage. All of the control rods in Unit No. I have very low exposures and are not anticipated to exceed 34 percent B-10 depletion prior to the end of this operating-cycle. For this reason, we feel that there is no reason to include the boron loss phenomenon into the shutdown demonstration at this time.
Mr. Jrmes P. O'Railly-S2ptimhar 26,'1980 r
W If you have any questions regarding this information, please contact my staff.
Very t uly yours,.
$.f B
J. Furr Vice President Nuclear Operations DCS:kbb*
cc:
Mr. Norman C. Moseley l
l 1
e; -
v e s= 4.sw hw w,m. Wp w
- -, e e ww w.w, -,.
.w...,+..-.e, g
4,y,gs.e,e,w..
- -