ML20049J135
| ML20049J135 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 07/07/1981 |
| From: | Linder F DAIRYLAND POWER COOPERATIVE |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| TASK-15-07, TASK-15-7, TASK-RR LAC-7658, NUDOCS 8203120132 | |
| Download: ML20049J135 (5) | |
Text
e D DA/RYLAND h
[k COOPERAT/VE eO soxsi7 2615 EAST AV SOUTH LA CROSSE. WISCONSIN S4601 (608) 788 4 000 July 7, 1981 In reply, please refer to IAC-7658 DOCKET NO. 50 1109 U. S. Nuclear Regulatory Commission m
e Attn:
Mr. Darrell G. Eisenhut, Director 6
g Division of Licensing NFCEjDO Office of Nuclear Reactor Regulation Division of Operating Reactors S
4"W,f y N'OfL
'g Washington, D. C.
20555
.C
^
x SUIh1ECT:
DAIRYIAND POWER COOPERATIVE IA CROSSE BOILING WATER REACTOR (IACBWR)
SEP TOPIC XV.7 N
LOSS OF RECTRCUIATION IT,0W
REFERENCE:
(1) DPC Letter, IAC-7387, Linder to Cisenhut, dated February 27, 1981 Gentlemen:
Enclosed find the Safety Evaluation Report for Loss of Recirculation Flow (SEP Topic XV.7) which we have prepared for the La Crosse Boiling Water Reactor.
Our letter, Reference 1, identified topics for DPC to submit for NRC evaluation.
The subject topics were listed in the schedule submitted with Reference 1.
If there are any questions regarding this report, please contact us.
l Very truly yours, l
DAIRYIAND POWER COOPERATIVE 0 Ass 1/v w&v/{f Frank Linder, General Manager FL:JDP:ee ec:
J.
G. Keppler, Reg. Dir., NRC-DRO III NRC Resident Inspectors b
D O 6' \\
8203120132 010707 PDR ADOCK 05000409 P
.m LA CROSSE BOILING WATER REACTOR SYSTEMATIC EVALUATION PROGRAM SAFETY EVALUATION REPORT 70PIC XV-7 LOSS OF RECIRCULATION FLOW
, INTRODUCTION The safety objective of this topic is to assure that the consequences of a reactor coolant pump rotor seizure or reactor coolant pump shaft break are acceptable; i.e.,
that no more than a small fraction of the fuel rods fail, that the radiological consequences are a small fraction of 10 CFR Part 100 guidelines and that the system pressure is limited in order to protect the reactor coolant pres-sure is limited in order to protect the reactor coolant pressure boundary from overpressurization.
EVALUATION Loss of Recirculation Flow The loss of recirculation flow has been analyzed for La Crosse (Reference 1).
For this accident, it is assumed that there is a loss of one or both of the recirculation pumps while the reactor is at full power.
This results in a high heat flux due to the heat capacity of the core in conjunction with a lower than normal coolant flow rate.
Mechanisms for the loss of one or both pumps are a two-pump trip, a one-pump trip, seizure of one pump, a pump shaft break, and a flow control failure.
STARTING CONDITIONS AND ASSUMPTIONS (SEE REFERENCE 1) i Coolant flow through the LACBWR core is supplied by two pumps in two coolant loops.
A loss of flow through the core may result-from any one of the following:
(1)
Complete decoupling of.each pump from its motor.
(2)
Loss of power to each pump drive motor.
(3)
A single pump seizure (partial loss of flow).
.(4)
Loss of power or a complete decoupling of a single pump (partial loss of flow.)
(5)
Pump shaft break.
,. ~
l i
\\
The starting conditions and assumptions for this transient have been chosen such that a conservative estimate of the transient results.
The assumptions are as follows:
(1)
The reactor is initially operating at 102% of rated power.
(2)
Both recirculation pumps are lost.
(3)
No credit is taken for a scram resulting from the event that caused the loss of both pumps.
(4)
The reactor scrams when the recirculation flow is 30% of full flow.
(5)
The reactor is operating at the beginning of a fuel cycle.
RESULTS AND CONSEQUENCES As indicated in Reference 1, Reference 2 and Figure 1, reactor power decreases rapidly due to the increase in voids as the recirculation flow decreases.
The reactor scrams when the recirculation flow has decreased to 30% of full flow.
CPR calculations for this transient demonstrate no fuel failure as it stays above 1.32 at all times.
7-REFERENCES (1)
" Response to Question 4'- Transient Analysis of LACBWR Reload Fuel, prepared by Nuclear Energy Services, Inc.,
NES Document No.-81A0025, February 18, 1977.
(2)
" Additional Information to' Supplement No. 3 - Part II",
DPC Letter, J. Madgett to R. Reid, NRC, LAC-4654, dated April 27, 1977.
i o
200 200 160-
-160 mw2 120-
-120 x O
D a.
Ati.
%O E*
E*
U w
=
E f e a t. Flux 80-80 *
, 0-
- 40 4
ower C-i 3
3 0
5 5
5 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 tit 1E Ili SECONDS FIGURE 1 LOSS OF RECIRCUIATION FLOW (Reactor Power and IIcat% Flux versus Tie.e)
_____.....L.A._
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