ML19345C351
| ML19345C351 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 11/26/1980 |
| From: | Delgeorge L COMMONWEALTH EDISON CO. |
| To: | Youngblood B Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19345C352 | List: |
| References | |
| NUDOCS 8012040481 | |
| Download: ML19345C351 (2) | |
Text
e
, i' '
Commonwealth Edison one First National Ptar9. Chicago Ilknois Address Reply to: Post Othee Box 767 Chicago, I!hnois 60690 November 26, 1980 Mr. B.
J. Youngblood, Chief Licensing Branch No. 1 Division of Licensing U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
LaSalle County Station Units 1 and 2 Response tc Informal NRC Questions Suppression Pool Temperature Analyses NRC Occket Nos. 50-373/374
Dear Mr. Youngblood:
In response to q 3tions pasec. :y Mescis.
A.
Bournia and N. Su of the NRC staf f the week of November 17, 1980, concerning transient analyses reported in the LaSalle County DAR Section 6.2, the following information is provided:
1.
The RHR System is intended for operation in its containment cooling mode as described in 6.2.2 of the LaSalle FSAR.
This includes operation during containment isolation.
The RHR A and B loops depend on the "24 A&B" valves respectively to permit flow.for pool cooling.
The valves open by manual control switch operation in the control room with permissive logic based on closed valve position in alternate flow paths from the RHR heat exchanger.
Once closed the valves involved with the "24" valve open permissive cannot automatically reopen.
This shall ensure continued availability of the RHR pool cooling mode, once initiated.
2.
Attached is our proposed revised SORV procedure specifying i
minimum number of closure attempts and time to scram after SORV.
m a
h:
i3.
Chapter 6 of the LaSalle DAR includes analysis of maximum pool temperature in which the worst cases were postulated.
Conservative initial conditions, and worst cases of heat addition to the suppression pool were assumed.
Our analysis then assumed the worst single failure to P,
calculate maximum pool temperature:
a) a stuck open
'l '
relief valve (SORV), and b) loss of one loop of RHR.
The DAR cases bound FSAR Chapter 15 analysis because the above non mechanistic assumptions minimize heat removal from containment.
90l s/
8012040 N
/f
2-4 The'LaSalle analysis used the same assumptions as the GE Mass Energy White. Paper which states in Section IV -
Assumptions "All transients involving one RHR HX operation assume a minimum controlled depressurization rate and will employ a rapid transfer (16 minutes) from pool _ cooling to
' shutdown cooling using the available RHR HX when the reactor vessel pressure reaches the permissive value" that is, when RHR discharge pressure is greater than Reactor pressure.
5.
The time involved for a. suppression pool temperature rise between 1000F and 1100F is 5 to 6 minutes.
If tnere are any further questions in this regard, please contact this office.
Sincerely, t
F L. O. DelGeorge Nuclear Licensing Administrator Attachment cc:
RIII Resident Inspector - LaSalle
-)..
t i
N r;
8493A L
1 O
l A AC-E
~~
NOT l
,E J A O.~~.
NO. OF PAGES C DUPUCATE: ALREADY ENTERED INTO SYSTEM UNDER ANO.
QIGIBLE:
HARD COPY AT:
M C CF C OTHER
.