ML20125A566
| ML20125A566 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 11/14/1969 |
| From: | Danielle Sullivan US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Moore V US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 9212080396 | |
| Download: ML20125A566 (3) | |
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- November 14, 1969 C
Files THRU oore, Chief, Instrumentation & Power Technology Branch, DRL
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SECOND REVIEW OF INSTRUMENTATION SCREMATICS, MONTICEL1D NUCLEAR GENERATING PLANT; DOCKE't #50-263 Tom Ippolito and I met with the applicant and his representatives for the second time on November 4 for the purpose of completing our review of the instrumentation schematics. We were also able to resolve the two outstanding items from our first meeting of October 16 - 17 (Ref. RT-785A, dated October 22, 1969).
The schematics remaining to be reviewed were the following:
1.
Emergency Power (Onsite) 2.
D-C System 3.
Standby Cas Treatment System 4.
Auto Blowdown System 5.
Dryvell Purge and Vent (Containment) Isolation i
In attendance were NSP_
M. N. Bjeldanes G. Yanagita A. W. McDermid M. Clarity Bechtel J. V. Carlson C.E.
G. L. Davis M. Lane l
J. W. Lingafelter M. R. Muir L. Wolf i
M. Clinton AEC_
T. Ippolito l
D. Sullivan j
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9212000396 691114 PDR ADOCK 05000263
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e Honticello 2
November 14, 1969 1.
Emergency Power (Onsite)
Our review uncovered the fact that failure of a single generator lockout relay would result in the failure of all onsite generating systems.
The applicant agreed to correct the deficiency and submit a safety analysis of the modification.
We found no other deficiencies.
2.
D-C System The d-c system comprises two redundant batteries and distribution systems.
Each system is respectively assigned to redundant func-tions in the Emergency Power and ECCS control circuits.
Our review disclosed that the two d-c systems are not completely independent since several buses, upon loss of voltage, will trans-fer to the alternate source. This schene always places the total system in jeopardy of failure from a common cause; specifically, the fault which caused the loss of the first source.
The applicant has agreed to remove this lack of independence by making the system " split-bus" throughout.
The redesign will then be consistent with the Emergency Power (Onsite) and Protection System designs.
We found no other deficiencies.
3.
Standby Gas Treatment System Our review indicates that the system satisfies the single failure criterion. The two redundant subsystems, however, are not indepen-dent since the alternate subsystem operates only upon failcre of the " preferred" subsystem.
The applicant and the staff have studied this matter and it appears that there is no practical way of devising a split system in which both subsystems are started independently (and simultaneously).
The difficulty arises from the fact that a specific value of air flow is required through the common duct.
Thus, the control system which held the flow at this constant value whether one or both subsystems were operating would, itself, become a source of common failure modes.
The applicant has stated that he will retain the design originally 1
proposed except that he will provide some additional independence between flowneters in the common duct. The details of the modifica-tions will be sent to us for evaluation. We will then judge the acceptability of the total SGTS.
I There were no other areas of concern, or deficiencies.
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Monticello 3
November 14, 1969 4.
Auto-Blowdown System The schematics of the Auto-Blowdown System were reviewed and found to be satisfactory.
5.
Drywell Purne and Vent (Containment) Isolation The schematics were reviewed. We found no deficiencies.
There were two outstanding items from the last meeting Further review of the Refueling Interlock schematics indicated that the system, as originally proposed, is acceptable. This item is resolved.
The common failure mode of several isolation valves has been removed by feeding the control circuits of the d-c valves from their own source of motor power rather than from the source which controls the a-c motor power of the redundant valves.
This item is resolved.
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D. F. Sullivan Instrumentation & Power RT-857A Technology Branch DRL:1&PTB:DFS Division of Reactor Licensing cc:
F. Schroeder S. Levine l
R. Boyd i
R. DeYoung D. Muller D. Vassallo J. O'Reilly 1
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