ML20058K611
| ML20058K611 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 03/09/1977 |
| From: | Mayer L, Wegener D NORTHERN STATES POWER CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| NUDOCS 9102120649 | |
| Download: ML20058K611 (4) | |
Text
I LICENSEE EVENT REPORT CONTROL BLOCK l l
l l
l l
l (PLEASE PRINT ALL AEQUIRED INFORMATCN) 1 6
LcENSEE t ICE NsE EvfNT NAME tcENSE NUMBER T Y PE TYPE lM lN lM l N l Pl 1l l 0l 0l-l0 l 0 l 0l 0l 0l-l0 l0 l l 4 l1 l1 l1 l1 l l 0l 1l o
7 89 14 15 25 26 30 31 32 CATEGORY TP S U CE DOCKET NUMBE A EVENT DATE AEPORT CATE
@ CON 7 l l
l l0 l5 l0 l-l 0 l 2 l 6 l 3l l0 l2 l2 l3 [7 l 7 l l0 l3 l0 l9 l7 l7 l 7 8 57 58 59 60 61 68 69 74 75 80 EVENT DESCRIPTION gg uring a reactor startup, the withdrawal of an in-sequence centrol rod resulted in a l
7 89 RO
@ beriod less than 5 seconds and an IRM scram.
The IRM was on range 1 which is cali-l 7 89 80 35 lSra ted to scram a t less than 0.0015% of rated reactor nover.
Previous analyses show l
7 89 AO EE lthat fuel enthalov criteria are not exceeded for reactivity insertions in excess of l
7 89 Q lthat expe rienced. The R101 was operable and not bypassed. No technical specifications l oO 7 89 PWE 80 systEu CAUSE COMP 0NENT COMPONENT CODE CODE COVDONENT CODE SUPPLK R MANUF ACTURE A v0 LEON l E l E l
[_ F) lE lE lE l El El El lE l lZl9l9l9l l Nl o
7 89 10 11 12 17 43 44 47 48 CAUSE DESCAIPTION CB bhe s c r tm oc m cre d 10. 25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> after a shutdown f rom ful l n eve r-xenon was rea r i ts l
7 89 a0 ll l transient peak.
Reactor moderator temperature was 480 F.
The combined negative re-j.
7 89 ao DE l activity of xenon and high temperature at the time of startup required withdrawal of a 7 89
-j F ACitr' Y VETHOD OF STATUS
% POVt E A OTHEA STATUS OrSCOvEAv D'5 COVE Av OE SC AiPTtCN 8
Lcj l0l0l0l lM l
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KA l
7 8 9
10 12 13 44 45 46 80 FCAM OF ACTIV;T V CONTENT REL E ASED OF AE LE ASE AMOUNT OF ACTtv>T V L OC A TON CF pf LE ASE l El l
Sk SS l
7 8 9
10 11 44 45 80 PEASONNEL EXPOSURES NuveE A
'vPE ot sCAiP?rCN 1 0 1 01 01 LZJ l NA I
1 7 89 11 12 13 BO PERSONNEL INJUR!ES suvBE A DESCApTON DE I O I 01 Ol i
x4 I
7 89 11 12 80 OFFSITE CCNSEQUENCES h lM l
7 89 LOSS GA DAMAGE TO FACILITY 50 T wE ot sCm-c N l NA 1
l 7 89 10 9102120649 770309
l 7 89 e3 ADDITIONAL FACTORS E l_T' vent Descriotion and Cause Description are continued on a separate sheet.
l 7 89 80
. qt-y of 3
eO NAVE DANTR r.hBPIR PHONE-N h k M)1
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RO 50-263/ 77-04 EVENT DESCRIPTION CONTINUED were violated. All applicable pre-startup checks were perfonned and operating procedures were being followed.
This is the first event of this kind at Monticello.
The designated rod withdrawal sequence being followed was developed using the Haling withdrawal principle.
In the next cycle the generic Banked Position Withdrawal Sequence (BPWS) will be used; in-sequence rod worths using the BPWS are expected to be lower.
Until that time (Fall '77) additional analysis to identify high reactivity worth rods will be performed for each rod withdrawal sequence used. We do not consider this event to be a safety problem.
Steps are in progress to alleviate the potential for recurrence of such an operational problem.
Technical Specification 6.7.B.1.d defines "short term reactivity increases that correspond to a reactor period of less than 5 seconds" as a Reportable occurrence. (R0 50-263/77-04).
CAUSE DESCRIPTION CONTINUED significantly greater number of rod groups than normally experienced before reaching critical.
The reactor was just critical in the rod configuration j
shown in the attached figure.
The designated rod withdrawal step called for withdrawing rods 06-27 and 46-27 from position 00 to position 10.
These l'
rods were individually moved to position 06 as shown, making the reactor approximately critical. When rod 46-27 was withdrawn an additional notch from position 06 to 08 the reactor immediately scrammed.
Our core analysis group anniyzed the worth of rod 46-27 at various positions, with other rods in the position shown. Calculations were done using hot (545 F) and cold (68 F) models, with results corrected to 480 F, and the xenon distribution existing at the time of the scram. The results are as follows:
Position Cold Delta K Hot Delta K 06 - 08
.0047
.0052 00 - 10
.0127
.0104 We believe that these calculations conservatively bound the possibic rod worths and that the hot calculation is most representative because it involves a smaller temperatore correction. Both calculations are consistent with measurements.
i evr 4
I f
RO 50-263/77-04 51 l
47 0
0 0
43 10 0
0 10 39 0
0 0
0 0
35 0
0 0
0 s1 0
0 0
0 0
27 6
'O O
0 0
06 23 0
0 0
0 0
19 0
0 0
0 15 0
0 0
0 0
11 10 0
0 10 07 0
0 0
l 03 I
i 0
02 06 10 14 18 22 26 30 34 38 42 46 50 Ntchers give control rod positions Blanks are fully withdrawn (position 48)
Monticello Critical Control Rod Pattern on 2/23/77 s
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1 MSP NORTHERN STATES POWER COMPANY MIN N E A Pou s. MIN N E SOTA 55401
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March 9, 1977
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Mr J G Reppler, Director, Region 111
\\'I Office of Inspection & Enforcement Y
s U S Nuclear Regulatory Cornission t -
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799 Roosevelt Road Glen Ellyn, IL 60137
Dear Mr Keppler:
MONTICELLO NUCLEAR GENEPATING PIAIG Docket No. 50-263 License No. DPR-22 Reactor Period Less Than Five Seconds The Licensee Event Report for this occurrence is provided on the attached pages. Enclored are 3 copies.
Yours very truly, hr L 0 Mayer, PE Manager of Nuclear Support Services LOM/ME'/deh cc: Director, IE, USNRC (40)
Director, MIPC, USNRC (3)
G Charnoff MPCA Attn:
J W Ferman 77 07 O~d/86
-over-
.-.