ML19322D167
| ML19322D167 | |
| Person / Time | |
|---|---|
| Site: | Hatch, Rancho Seco, Crane |
| Issue date: | 04/25/1978 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Grimes B Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19322D168 | List: |
| References | |
| TASK-TF, TASK-TMR 78-04, 78-4, NUDOCS 8002100004 | |
| Download: ML19322D167 (2) | |
Text
.
E.,
n.
~
f
. /3.
IDi 3
Y Date:
KPR 2 5 yyy Q.1'.
Serial No.':
IE-ROI: 78 f.5
- a. ;.
i_-E.
TRANSFER OF LEAD RESPONSIBILITY
.y n..
TO,:
- 8. K. Grimes, Assistant; Director fo6 Engineering and Projects, NRR
==::-
SUBJECT:
RANCHO SECO NON-NUCLEAR ~ INSTRUMENTATION POWER SUPPLY AND L......
EEEI' AUXILIARY FEEDWATER INITIATION E.C
~
RESPONSIBl.E ASSISTANT DIRECTOR:
K. V. Seyfrit
. TEE.'.
m..=. -
DESCRIPTION OF ITEM REQUIRING RESOLUTION:
h.
-9~.;,
At Rancho Seco on March 20, 1978, an inadvertent loss of power to ey.;
non-nuclear instrumentation resulted in loss of approximately two-
~+ -
thirds of the temperature, pressure, flow, and level signals.
iff=
=~
Although the reactor tripped properly, the operator did not have enough working instrumentation to provide the information necessary
~. ".
for adequate control of primary cooling system temperature ;nd
?""
pressure. As a result, the operator pumped too much feedwater E
to the steam generators and overcooled the primary cooling system.
=
- Limiting conditions for operation re primary cooling system pressure and temperature reduction rate were exceeded.
Loss ^ of power to three of seven non-nuclear instrument panels occurred while an operator was replacing an indicator lamp'in an illuminated "EE Sr push-b'utton control switch. The lamp was dropped causing a short to ground. The three panels rec.eive power from two 24 volt DC
[!,.
power supplies connected in parallel.
The short caused a circuit breaker to open in each of two 120 volt AC lines which feed the 24 volt DC power supplies.
By the time the circuit breakers were x
closed, the primary cooling system had been subjected to a 300'F/hr-
_..P "
temperature transient.
When the pressure of the primary cooling system dropped to 1600 psig, a safety features actuation signal was. generated.
This signal causes rz; both auxiliary feedwater pumps to automatically provide maximum flow 7"~#
to both steam generators. This feature of the safety features f=g~6 F"~~
actuation system contributed to the temperature transient which t. primary cooling system experienced. At some B&W reactors, e.g.,
G.;
~
CC :s-Besse 1 and Crystal River 3, a safety features actuation signal does not initiate maximum flow from the auxiliary feedwater p
L pumps.
=20..
IE.
f:,.--
CONTACT:
R. W. Woodruff. TP 5.7 49-28180 f."
g 8002100 g,.
I --
f.
=
-~
=.
~ ~ '. *..
B. K. Grimes 2
ppg g y 39,8
.. 'h:
i:
)
W~
f RECOMMENDATIONS AND PROPOSED' COURSE OF' ACTION:
~
9:,.
1.
For Rancho Seco, NRR will review the supply of power to non-
=.
nuclear instrumentation to determine whether design changes L. 2,
are necessary to reduce the loss of information which can result r
lii.t from loss of power.
2.
If NRR concludes that design changes are necessary for the power
- ..=
supplies for non-nu'elear instrumentation, NRR will perform a
~=
generic review of this area for other B&W units.
.2:.t
- -....g f.?.!
- 3.,NRR will review automatic initiation of auxiliary feedwater
. flow when' a safety features actuation signaT is generated and
~~1 MITT'~ determine.whether this f..ea.t.ur.e. sh.ou.ld..be.. ret.a.ined.for
- .. =
-~
.~
g 0_ _,A 4.
NRR will evaluate the susceptability of B&W plants to other
~ = = = -
~~~
initiating events or failures which could cause similar significant cooldown transients and initiate such corrective action as is g,
deemed necessary.
,5 IE will provide assistance as necessary and will assure compliance
~
with any new or revised requirements.
CONCURRENCE:
==y
-;;g 7
'%, EW m:&
v4/n "fii:1-
'Date Karl V. Seyfrit,}, Assistant Director, DROI, IE l
}
[
S/?sY...
&L y
o x.c.-4.-
[
.B. K. Grimes, Assistant Director.for Engineering & Projects, NRR Date e
t....
Enclosures:
i Letter from SMUD to RV dated 3/31/78 re Reportable Occurrence 78-1.
- ==
2.
Memorandum from Crews to Seyfrit dated 4/6/78 re Rancho Seco temperature T{.
~.F".
cc:
V. Stello, NRR B. H. Grier, RI
- ~~
R.J. Boyd, DPM J. P. O'Reilly, RII
~
W. B. Zwetzig, D0R J. G. Keppler, RIII J. G. Davis, IE-G. L. Madsen, RIV N. C. Moseley, IE R..H. Engelken, RV H. D. Thornburg, IE D. G. Eisenhut, NRR J. H. Sniezek IE
.