ML19312C843
| ML19312C843 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 01/26/1977 |
| From: | Burnett P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Dance H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| Shared Package | |
| ML19312C835 | List: |
| References | |
| NUDOCS 8001100809 | |
| Download: ML19312C843 (3) | |
Text
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fJUCLEAR REGULATORY COMMIN,' N UNii! O ST A TCS
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l.,e-T.p K's January 26, 1977
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IE*:0RA!:D'I! TO:
H. C. Dance, Chief, Peactor Projects Section No.1, l
Reactor Operations and Huclear Support Eranch, Region II FROM:
P. T. Burnett, Reactor Inspector, Nuclear Support Se: tion, j
Reactor Operations and Huclear Support Branch, Region II i
SU3 JECT:
UURESOLVED ITEM RELATED TO OCONEE POWER DOPPLER COEFFICIEUT (DOCKET UO. 50-C87) i
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The stee=-line-break accident is the one event in which the negative j
f doppler coefficient does not contribute to reactor stability or l
j safety, but instead promotes a return to criticality as the plant, over-cooled by the break, recovers the reactivity tied up in the i.
integral cover coefficient.
At issue is the question of a taxit:un magnitude, Inost negative value, I
limit on the power doppler coefficient. In other vards, should the i
pinnt be allo.ed to operate with a power coefficient nore negative than tha5 used in the analysis of the steam line bre?k accident?
Does the existence of a core negative power doppler coefficient imply an unreviewed safety question as defined in 10 CFR 50 59?
A related question is that of different conclusions regarding the l
change in doppler coefficient with burnup. BM! calculations chov becomes_nore_negat_ive, with.burnup.gants that the mower coeffic_
for both the Oconee and B-SAR 205 e
calculates that tha._ coefficient _ beceres_lers_Jtecative with_emsurch.
The Westinghouse argument that clad collapse ento the fuel pallet, which reduees ecterage fuel tenperature, dominates all counter effects is peraussive. The fuel designs are si:ailar:
References:
1/ B-SAP.-205, Tables h.3-h & h.3-10, BMi.
J/ "Pressufized Water Reactor Syste:as Manual." p 1.1-23 et seq &
Figure 1.1-7, W.
CONTACT:
P. T. Barnett 221-6323
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C.. D*snce Oconce (B&'J)
Vestinghouse 15x15 fuel bundle 157.15 array rod pitch, in 563 568
.h22
.h30 clad o.d.,
in.
clad thickness, in.
.02h3
.0265 direcetrical gap, in.
.0075.0085
.007 pellet diameter. in.
36h9.3659 370 92-9h5 of TD 93 5%
pellet density Based upon the similarities in the above design features, there is no obvious reason for fuel from the two vendors to have different doppler-trend characteristics with respect to burnup.
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. T. Burnett Reactor Inspector I
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