ML19325E519
| ML19325E519 | |
| Person / Time | |
|---|---|
| Site: | Fermi, LaSalle, 05000000 |
| Issue date: | 10/31/1989 |
| From: | Morgan W COMMONWEALTH EDISON CO. |
| To: | Murley T Office of Nuclear Reactor Regulation |
| References | |
| 0350T, 350T, NUDOCS 8911070338 | |
| Download: ML19325E519 (6) | |
Text
_ _ _ _ _... _.
L Commonwealth Edloon
! ' g.g
(
72 West Adams Street, Chicago, Illino:s.
t
, Address Reply tJ: Post Office Box 767 i'~
Chicago,lihnois 60690 0767 October 31, 1989 f4 Ob hNA l Ct*>
9
& ( $ g [lt L u du Dr. Thomas E. Murley, Director dtE, hs M:t Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission NCM b S N4t g
/I Hashington, DC 20555
'gf,
k
Subject:
LaSalle County Station Units 1 and 2 Safety Parameter Display System (SPDS) Validyne CM-249 Isolators NRC Docket Nos. 50-373 and 50-374 References (a):
A. Bournia letter to D.L. Farrar dated March 4, 1989.
(b):
C.M. Allen letter to U.S. NRC dated March 20, 1987.
(c): Qualification Test Report QTR87-018
" Maximum Credible Fault Tests (M249-Q2 Carrier Modulator for Fermi 2 SPDS.
(d):
R. Swire letter to S.R. Dileto (not dated).
Dear Dr. Murley:
Refer 0nce (b) indicated that Commonwealth Edison's LaSalle County Station was to notify the NRC regarding actions which would be taken concerning the Va11 dyne CM-249 isolators installed in the SPDS system at LaSalle.
This notification was to take place following the resolution of this issue with the Detrolt Edison Company (DECO).
Detroit Edison has received verbal approval from the NRC of DECO's Qualification Test Report (Reference (c)) resolving this issue.
Issuance of the final SER is anticipated in the near future.
The following attachment provides information necessary to respond to the NRC request for additional information (Reference (a)) regarding the LaSalle County Station Validyne Isolator CM-249.
b[6 0350T:1 0
1 9
8911070338 091031 i\\\\
PDR ADOCK 05000373
\\
P PNV
s-Dr. T.E. Hurley October 31, 1989 If there are any further questions regarding this matter, please contact this office.
Very truly yours, d{0 i
WayQ E. Morgan Nuclear Licensing Administrator n'
Im i
Attachment cc:
P.C. Shemanski - Project Manager, NRR 1
A.B. Davis - Regional Administrator, Region III l
Senior Resident Inspector - LSCS i
l l
l-l D
l i
l i-l l
l' l:
1' 0350T:2 l
l,
ATTACHMENT l
L&MLLE COUNTY STATION UNITS 1 AND 2 SAFETY PARAMEIER_Dl1 PLAY SYSTEM (SPDS) l BLIDlEE. CM-249 ISOLATOR - NRC REOUEST FOR AD.DIT10NAL INFORMATION In response to the NRC request for additional information concerning the Va11 dyne CM-249 isolators installed in the LaSalle County SPDS System, Commonwealth Edison is submitting the Detroit Edison test report (Reference (c)) which is applicable.to LaSalle County Station based on the following three items:
First, the isolator model tested by DECO was a Va11 dyne CM-249-Q2.
However, the isolator model furnished for LSCS was a Va11 dyne CM-249.
It has been verified through Reference (d) that both isolator models are functionally and hardware identical.
Second, the acceptance criteria stated in DECO Test QTR87-018 requires that when 120V AC,-60 Hz from a 20 ampere source is applied to the Va11 dyne C -249-02 outage terminals, no disturbance larger than 10 mV
-steady state shall be measured at the input termir.als. Voltage transients larger than 10 mV may appear at the input provided that they persist for i
no longer than 20 ms.
This is based.on an allowable error in the IE signal of 1% of the span, as explained in Appendix'C to QTR87-019.
This criteria is applicable to LaSalle County Station noting the following points:
a.
The LSCS instrument loops identified with Va11 dyne isolators l
CM-249 do not have trip units connected.
These instrument loops are used for indicating or recording purposes only, b.
Instrument loops with signal levels of 0-ImA DC, 2-40mA DC and 10-20mA DC will not be affected because each instrument loop is driven by a power supply and the addition of a 10mV steady-state disturbance falls within the tolerance of this power supply.
c.
Instrument loops with signal levels of 0-1V DC and 1-4V DC will introduce an error of 1% or 0.25%, respectively, of the span in the indicated readings (i.e.. a 10mV error on a scale of 0-1000mV or 0-IV equates to 1%). He feel the error introduced by this disturbance of 10mV is not going to significantly change the indicated readings.
0350T:3
r Please note that the error identified in Item (c) is over and above the inaccuracy which exists in the instrument loop under normal operating conditions.
He have not performed calculations to determine this instrument loop inaccuracy because these calculations were not required in the past.
The percentage addition of error-in the total inaccuracy due to the 10mV steady-state disturbance is, therefore, unknown.
Third, the maximum credible fault applied to the Va11 dyne Isolator in Qualification Test Report QTR87-018 current envelopes the fault currents available in panels at LaSalle.
The largest power sources in these panels are 120V AC with a 30A circuit breaker and a 125V DC with a 100A circuit breaker.
In the test the power source was 120V AC with a 20A circuit breaker.
Additionally, a calculation has been prepared which shows that the limiting factor in the maximum credible fault of the Valldyne Isolator was not the size of the protective device in the power source, but rather the isolator output impedance.
In this calculation, an unknown impedance ZTH was assumed as part of the Thevenin equivalent circuit for a 120V AC source.~ In the Valldyne test, an additional hnpedance, Ry was added in series with Z Since Ry between Points 1 and 4 on the output terminal strip of the TH-isolation was measured on a spare isolator to be 3.3 OHMS, the maximum credible fault current through the Validyne CM-249-QZ isolator could not have exceeded 120V AC/3.3 OHMS = 37 amps, regardless of the source impedance in the circuit.
The resistance across Points.2 and 3 on the output terminal strip of the isolator was larger (104.9 OHMS) and, therefore, the maximum credible fault through these terminals is only 120/104.9 OHMS - 1.14' amps.
It should te noted that the maximum fault current would be lower than 37 amps in the 120V AC case due to isolator reactance which was not included in the calculation.
The magnitude of the' fault current produced by the 120V AC source will be the same regardless of the size of the breaker (i.e., 20, t
30, 100A, etc.).
Therefore, the maximum credible fault applied to the Va11 dyne Isolator in Qualification Text Report QTR87-018 envelopes the maximum fault currents available in panels at LaSalle.
Also, in the Qualification Test, the fault current was interrupted in every case by the isolator internal fuses.
These % amp fuses are capable of f
interrupting 300 amps at 125V DC and 50 amps at 125V AC.
As shown by the fuses' time-current characteristic curve, which is provided as Sheet 29 of Appendix A to Report QTR87-018, at 1 amp, these X amp fuses have an interrupting time of 7 msec.
For higher fault currents, the interrupting time decreases logarithmically.
It should be noted that the inter-rupting time of 7 msec is well below the 20 msec transient duration allowed by the test acceptance criteria in Appendix C of this report.
Therefore, any increases in the transient magnitude caused by the introduction of a DC rather t
than the tested AC voltage source would be interrupted by the opening of the isolator unit fuses prior to the 20 msec transient duration which is allowed per the test acceptance criteria.
0350T:4
s g *.. m. 4. y p A
m j
s o. <
TRANSOUCERS o INSTRUMENTATION e ELECTRONICS i
R Mg 8038 Wilbur Avenue.Montwtege, Californes g1334 Teles 461303 n
W M*
,818 8003067 1,
Toll Fros 800 423 8051 temolut,'eg AK, CA, and HI) '
S ggggg,gm a i.
,l
.Ceemenweatt Edison PO Ben 767-K ChIcaso. IL.60690-0767 1
)
L Attn : -
Samuel R. Dileto
.I Supv. Destgn Engineer-LaSalle,
'BWR Enginearing Dept.
<q
Subject:
LaSalle County Station Validyne Isolators y
ModeI CM249 U
Maximum Credtble Faults s
Dear'.Mr. Dileto:
J On July 22. 1987 Valldyne Engineering Corp. performed The Maximum l
Test on the CH249-Q2 Carrier Modulator..
The Credible Fault resulte.or this test are' documented in-our Qualification Test j
. Report
-QTR87-018 issued August,. 1987."
The Test Plan was' in i
response, to IEEE279.
Section 4.7.2, and reference to NUREC/CR-(
3493...
The test was performed at the request of Detroit
- Edison, L3
'who wtknessed'the testing.
e
- r
-The concluelone of the test weret b.
' "Thie' Maximum Credible Fault Qualtrication Test of the CM249-Q2 has demonstrated that a 120Vac, 60Hz, 20 Amp:rault applied to the output of the CM249-Q2 does not cause degradation of the-isolator l
L
' input:.elsnel beyond an acceptable level.'
The tests have shown
)
H that, a rau.! t originating in the non-c1 ass 1E output of the Iselater-does not errect the integrity of the safety-reiated input signal.
These.raulto have re'aulted in the protective ruses of the CH249-Q2-outy trcutts going to their open circuit condition.
This fautt currents and has prevented any other damage has bl
, nts and structure of the CH249-Q2.
Factory-level to' the o store normal operation of CH24o-Q2 unito wh!ch have L
rework
.'by fault currents on the output eircutts."
. been:
A.
A4.'your-request, I have examined the CH249 and the CM249-Q2.
Beth untto perform the same funetion.
In the same manner.
The e,chematice of the two ate the e,ome, down to the component values.
There are - minor difreroncos an const.ruction, aind there ic n r, tracabilIty on the componente io the CH249.
L In my.. opinion, tha
,r, m a t c :.n.
performed on en CH249 woutd givo L
steellar results sna cencl'tcionu.
rag.
V P
k-'-94g*-wpt-'-y-*w%
+
g
+-ywergey-g.-,q w, w ww--.w g g-1' Tw w -gr-ww ww
-a.we---ess
" N?'f &
" A4 I
t 1.
am. e.?olosing the schematice and final assemblies of the twc unite.in gumetten.
I believe you will come to the same i
i concluston.
1 I
t re arde, d
E Roy r Swire IV s;
Technical Contracts 1
I l
]
I o
r l!
.i J
i i
t I
I 4iii t
+s' k
k a-t t
4*N. r.
.. 9 -
l i
n 9
k I
I 1
2 1
,,l,
-v.-...-
e
n---
- - -