ML20128A831
| ML20128A831 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 12/04/1969 |
| From: | Danielle Sullivan US ATOMIC ENERGY COMMISSION (AEC) |
| To: | |
| References | |
| NUDOCS 9212030465 | |
| Download: ML20128A831 (2) | |
Text
,
~) '
.s < w k
UNITED STATES ATOMIC ENERGY COMMISSION
(
! 'l
.6 l'
I W ASWNGToN, D C. 20$45
?
December 4, 1969 Files
- "7/f//
TERU t V.# Mo6r, hief, Instrumentation & Power Technology Branch, DRL TEI40N REVIEW OF HONTICELLO PLANT SGTS SCHEMATIC DRAWINGS; DOCKET #50-263 As stated in my memo to files dated November 14, 1969 (RT-857A), the applicant had agreed at our November 4 meeting to provide some addi-tional independence between the redundant Standby Gas Treatment Systems CVI and to submit the details of the modification to us for review.
Dwgs #A511-3203, Sheets 1-3 (Chg. B) were subsequently sent to us.
To assist us in the review we arranged a conference call with the applicant and his representatives on December 2.
Participating in the call were NSP C. Ross C, E_.
G. L. Davis J. W. Lingafelter L. Wolf H. Clinton AEC D. Vassallo T. Ippolito D. Sullivan Functionally, the SGTS has not been changed; the " preferred" system (System A) is selected initially and, if it fails, System B is selected after a time delay of 50 seconds. 'rne modifications relate to the manner in which this is accomplished.
In the original design the control circuits of System A also controlled For exampic, the starting relays of certain portions of System B.
System B were deenergized by the relays in System A which were actuated when System A was successful. In sunar.ary, the two control circuits were not independent.
In the modified design there is complete electrical independence between There are two independent flowmeters in the common the two systems.
(we can call them 'A' and 'B') which control only their respective duct systems. For example, if System A fails to start, this condition would 9212030465 691204 DR ADOCK 05000263 PDR u
Telcon 2
December 4, 1969 t
be sensed by flowmeter 'B' which would then start System B independently of the System A controllers.
Thus, the only lack of independer.ce arises from the process itself. This does have at least one potential common failure modes a useless flow via a broken duct in System A which would l'
appear to System B as successful operation.
We were able to complete our review of the SGTS drawings during the course of the telcon.
....,..r.+-
D. F.-Sullivan Instrumentation & Power RT-902 A Technology Branch DRL:1&PTB:DFS Division of Reactor Licensing cc F. Schroedar S. Levine R. Boyd
[
R. DeYoung D. Huller D. Vassallo T. Ippolito 4
'Y vvt4'f TW$
q--
.p,W.3