ML20043D779
| ML20043D779 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 05/01/1990 |
| From: | Lipinski W ARGONNE NATIONAL LABORATORY, Advisory Committee on Reactor Safeguards |
| To: | Catton I Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-CT-1968, NUDOCS 9006110163 | |
| Download: ML20043D779 (2) | |
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- ARCONNE NATIONAL LABORATORY F2# 3NS 9 W 5 i M ass W i N e w t[lv.e 6 0 @ 9,.
T.) 1, 1990 Lt. Ivan Catton A:visory Comittee on Beactor SafeEuards U.S. Nuclear Regulatory Comission j *"s
" yJ Was*.ington, D.C.
20555 Lear Dr. Catton:
i 3ubject:
Cor.~ents on Comtined Thermal Hydraulic (T/H)
Phenomena / Core Ferformance S :comittee Meeting, April 27, 1990 There are two main issues to resolve with respect to the operation of t.ci nt.g water reactors:
1 Suppression of reactor power oscillations during normal operation.
2.
The mitigation of an Anticipatec Transient Without Scram (ATWS).
Fcr the first issue, the BWhs owners Eroup (BWROG) proposes to define extl s!cn boundaries in the power flow map which ensure stable operation.
Analysis is used to establish these boundaries, but the codes used to perform the analysis have not been adequately validated by comparison to experimental data.
More work is required on code validation.
The work performed by Broci: haven National Laboratory with the Engineering Plant Analyzer is not applicatle, because it is based on point reactor kinetics.
The BWh0C proposes with Option I-A that an automatic trip function be initiate: if the exclusion boundary is violated. With Option I-B the trip can te typassee if the stability monitor shows low measured decay ratio.
Option 1-C propcses to avoic the exclusien boundary during normal operation, but to use ne APRM-based scram protection for unintentional entry into the exclusion region.
The new scram protection - would not be based on crossing of the exclusion boundary, but would be based on the comparison of flux and delayed flux.
If the BWROG exercises Option 1-B, then they should present arguments as to why a trip should be bypassed to enter an operating region which may I
support core power oscillations (possibly divergent).
If the BWROG exercises Option 1-C, then additional analysis and confirming experiments are rsquired l
to demonstrate compliance with CDC-12.
The BWROG also proposed an Option 111 which would monitor small regions l
of the core and automatically detect and suppress oscillations.
This system gn j
would use a digital microprocessor, g
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o Any option that uses automatic trip (and bypass) features should be gh" designed to Plant Protection System requirements (Class 1E, etc.).
If digital
,G computers are used, then the system should be reviewed to the same level of 3
j detail as the Combustion EnEineering Core Protection Calculators, gg 1
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Dr. Ivsn Catton
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May 1, 1990 The second rr.a i n issue relates to A7WS.
To mitigate an ATWS event, General I2ectric proposed that the recirculation pumps be tripped and offered ass.arance that the core woule not exhibit power oscillations at reduced flow.
Tne operational data at LaSa!!e 11 demonstrated otherwise. The ATWS issue for to!!!r,g reactors rerr.ains unresolved.
Sincerely,
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r Walter C. Lipinski, Ph.D.
Reactor An&Iysis and Safety Division W:;:i:l l
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