ML20054D357
| ML20054D357 | |
| Person / Time | |
|---|---|
| Issue date: | 08/11/1981 |
| From: | Minners W NRC |
| To: | NRC |
| Shared Package | |
| ML19310B145 | List: |
| References | |
| FOIA-82-107, RTR-NUREG-0460, RTR-NUREG-460 NUDOCS 8204220626 | |
| Download: ML20054D357 (2) | |
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"',, In WASH-lq10 the staff occition was tnat a set; : e a.d civer:,e reactivit;.
hhutdownsystemwoulc.oeanacceptablemeansofre:acingtheprobabilityof
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ATWS everits.' However, the control roc 'aDsorbers were not reovired to be i
i diverse, only the drives and the trip system. Edsecuently in f;UREG-0460, the staff modified this position to recuire diven.*
in all parts of the reactivitf shutdown sp.; tem including the trip sy:
e*, the control rod drives and the contrci rod absorber sections.
l Consequently an autt r.ic boron injection syste a.:.ters to be the only acceptable and practicai fix for Bh'Tts.
However, r e ::ron injection system presents problems for both the staff and the in: :7.
Since the system j
can -hange reactivit;. relatively slo.ciy, tne sr.......r is delayed.
Consequently i
core cows. /fiow "-
niens and high suppressics poo' temperatures are calculated. This raises c>..-
. concerning core damage and cooling, containment integrity and F CI/:CI
.c :..~.ity.
Furthermore, 1
the questions of boron mixing and possible dilutic Ire not completely answered.
The industry concern is that spurious a: cticn will force long shutdown.
.f some control rot 3 oe inserted tr.e n :. -
j I ccald be resolved.
Tilt large early reduction i'. reactivity would prcbaci;. eli-ir.;te the calculated -
flow oscillations and reduce the suppressior cool :e peratures.
The
.nudio, of boron mixing and dilution woulc be e!'-i ned and spurious n
actuation would be a minor concern, l
i 4. 8204220626 820315 PDR FOIA:
EARLEYB2-107 PDR
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I Diverss a::;rcer :
.mns are feasibis., [ 1- -- > :.:' ce; ;en drives. cc4#
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completbly civers:,-
oiversity of the present crives coulc be increased'by i
replacir.c-tne prew: nycraulic control units scran discnarge valves with a..
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".another system.
I
-ry case a diverse trip system would actuate the diverse 3
diives.
Both the r-- rculation pump trip and bor09 injection system would
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be retained, but ' t' - :: cr. injection would be manual and only a means of going frc= hot to c:1. :nutcowr-s Given the statemen--.
- L' REG-0460 would such a cesign ce acceptable, not as anATWSpreventiv"1..c.butasanATWSmitigstionsyste-f
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