ML19256D275
| ML19256D275 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 06/09/1971 |
| From: | Danielle Sullivan US ATOMIC ENERGY COMMISSION (AEC) |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 7910170788 | |
| Download: ML19256D275 (4) | |
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V. A. Meere Chief. Elmetrical Systems Branch Divistos of ummeter Standards IMITEDGrfAT105 MEITDC, Tsarr MILE Tsraun NUCLEAR STATION, UNIT NO.1, DOCKER 30. 50-289 We met with the applisset and his eoesultants en May 21 to discuss the is11ewia6 1**""*
j a) Osetrol red patching.
b) Testability of ESF inteinetag sirtMts.
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- Ow MW W. F. Seheemse GPU J. L. C. Boehofer, CPU A. Schneesee BEL /AEC D. F. Sulliven DES /AEC a) Centrol End Fatching The purpose of the dieeuestem was to improve our understanding of this esoples sehens for seeigning rods to the various red groups.
Esek red is gives a pormemmet alpha-euseric designation (e.g. A1).
There are tus esenectare for each red loested is the vicinity of the vessel head. These connectors are the " starting points" for
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tus pathe of petaking'sistuits for each rod and are included in the destas to pensit the rede to ba disceenected for removal of the b., +.....
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head. Thece connector assemblies are treated as "hard-wired" circuits since thsy are used very infrequently and are equivalent to similar disconnects fotsid on all PWR's.
The first " path" of patched information comprises a hard-wired circuit from the rod to a " transfer switch" in the control room.
This path carries (a) the six-phase motor power and (b) the position indication derived from the counting of pulses to the rod motor.
The transfer switch connects the rod to the desired power supply (Croup 1, Croup 2, Auxiliary Power Supply, etc.).
The position
.information (pulse information) is hard-wired to the computer.
The second set of patching circuitry carries the rod position infor-ar. tion derived from the reed switches and limit switches. The wires e.strying the "zoon reference" position information, i.e.,
the O-25% -50% -75% -100% indications, are hard-wired. The reed switch l
information is patched to the appropriate one of the sixty-nine meters.
Maters will be assigned to various groups as the rod assignments are s
changed. Indications for a gives grre will, for ease of reading, be
, patched such that they are sostiguous.
L It still appears that.the'enly defense against patching arrors is the hard-wired "sene reference" (= Mention for each rod. For example, assume rods A1, A2, A3 and A4 are assigned to Group 6.
Operation of Crog 6 should cause responses only on the four appropriate sons reference indicators. - Te verify proper red assignment within the group of maters displaying reed switch information, all but one rod at a time can be transferred to the auxiliary power supply, with the one rod under scrutiny left on the group 6 power supply. That b
rod, say A3, should cause responses only os the A3 some reference indicator and en the reed-switch indicator now designated A3.
h Rigorous technical specifications will be required to enforce proper rod verification subsequent to patching operations.
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b) on-Line Testability of ECCS Initiating Circuits This discussion was directed primarily towards improving our under-standing of the gCCS systems' on-line testability.
In the Eigh Pressure Zajection system, each of the three instrument channels can be testad at power by injection of an analog signal.
l This requires, however, that the channel be tripped by the channel's I
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Filas test switch. When the channel is restom to operation, the test switch is reset and the bistablo can than be tripped to test the relay logic circuits for the channel. Further, since the relays are grouped among valves and pumps, it is possible, with an additional rotary switch, to trip the logic in the various 2/3 combinations such that valves but mot the pisipa (and vice-versa) can be operated.
The Low Pressure Injection systen is similar to the above except there is no provision for selectively tripping the logic relays by an additional switch. The reason is that the systen can be completely actuated on-line through bistable action with no deleterious results; the pumps simply operate against their check valves.
c) Battery Charger Monitoring The applicant proposed the following monitoring circuits to annunciate the loss of a charter:
1.
Imv battery voltage a charger will normally keep the battery
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- voltage at about 128 volts. Charger loss will result in an t.
j immediate drop to about 116 volts. The set point will be 125 volts.
2.
High battery current:
attery current normally approximates l
sero amps because of the floating action. Charger loss will l-result in an 4-adiate current increase.
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3.
There will be osa annunciator window for each d-c supply. Each l
window will be activated by the respective signals of 1 and 2, above.
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It appears that the monitoring system will be' acceptable. Our position on this matter, however, is not final.
d) We reviewed the switchyard circuits to determine if the design satisfies Criterion 17 given the following postulated event:
turbine trip with a concurrent single failure in the ganarator tripping system. Our concern was that a single failure might retain the generator as a motor until the resulting turbine lockup caused the stalled generator to look like a fault, thus forcing clearance of the entire switchyard (loss of all access to offsite power) by offsite breakers.
(If such were the case, it would then be necessary to show that the generator
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l Files could be tripped manually, and power restored, prior to a need for a-c power for residual heat removal purposes).
f Our review here showed that there are redundant generator tripping I
circuits, and that criterion 17 is satisfied in this regard, e) Se ng Bus Interlocks There are two swing buses, one in the a-c and one in the d-c systen.
During our review of the schematic diagrams (Ref. ESB Hemo to Files, dated December 29,1970), we deter =4 w that the design of the associated interlocks to prevent spurious interconnection of redun-daat buses, or the propagation of. fault to both buses, was t
satisfactory.
At this meeting we reviewed a design modification which defeats the s Ang h
action whenever an ESP signal is present. la other words, under accident conditions, t% avstem behaves as a split-bus.
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' our review indientee that the modification constitutes an inprovement, and that the overall designs r==mia acceptable.
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D. F. Sullives Electrical Systems Branch
' ~ - Division of Reactor Standards es:
- 5. u.a ame E. G. Came R. C. Defoung R. S. Boyd D. Skovbolt C. Long t
V. Moore I
.D. Ross I
A. Schweneer I
D. Sullivan I
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, 6/7/71 6/8/71 6/8/71 Forum ABC-318 (Rev.M3) AECM 0240
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