ML20024B278
| ML20024B278 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/16/1979 |
| From: | GENERAL PUBLIC UTILITIES CORP. |
| To: | |
| References | |
| TASK-02, TASK-05, TASK-2, TASK-5, TASK-GB GPU-2413, PROC-790416, NUDOCS 8307080211 | |
| Download: ML20024B278 (4) | |
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_.y DICTATION FR0!i E.A. WOMACK 4/16/79 (6:30 PM)
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INTERIM OPERATING GUIDELINE FOR RESPONSE TO ALLOW MAINTENANCE p.
t OF HPI SYSTEM ON LOW REACTOR COOLANT SYSTEM PRESSURE
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DISCUSSION
.i The initiation of the HPI system by the emergency safety system signals on
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low reactor system pressure should occur only in the case of over-cooling event or a loss of coolant accident. It should always be treated as a severe indicator of potential problems in the reactor. coolant system and the operator should take follow-up actions in accord with the guidelines to understand the
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cause for 'the HPI initiation before securing or reducing HPI flow.
i The difference between over-cooling type events and loss of "oolarit events,may
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c generally be recognized as follows:
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y In overcooling events the,r:eactor system will repressurize gradually r
following HPI initiation and the RCS temperature will iemain low if the i
r RC pumps are on.
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Subcooling on the RC (i.e. RC system temperature at least 50 lower than the saturated temperature at RCS pre'ssure) will normally reinstall automatically c,
and in this case HP! flow may be reduced in accord with the guidelines below.
Following.this the reactor system can be controlled in the usual manner. In overcooling events the indicated pressurizer level will go low and may go
- below the indicated range of the level instrumentation. The opefator should
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reestablish pressurizer level and subccoling before reducing HPI flow to assure
'that the overcooling event is in proper control.
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{W Loss of coolant events will generally be indicated by an inability to establish
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and maintain a subcooled condition in the reactor coolant system with the reactor coolant pumps on. The pressurizer level indication is not a reliable indication of system inventory in this case and should not be relied upon as a
,C basis for controlling HP1 flow. In this case the operator should follow the guidelines as given below.
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OPERATOR GUIDELINES i
1.
Following initiation of HPI on a low RCS pressure system full HP injection flows should be continued in the reactor coolant system until the operator
-can establish and maintain sub-cooled reactor coolant system conditions as indicated by the attached curve.
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l 2.
If less than full HPI system flows has been established on automatic instru=entation the operator should attecpt to secure full flows by
' manual' action.
l 3.
If a s.ubcooled reactor coolant system can be established with the reactor coolant pump on as indicated in the attached figure, the operator should reduce HP1 fl6ws to avoid filling the pressure solid and lifting the relief valve or pressure safety valves.
L 4.
If after reducing HPI flows sub-cooled rynditions cannot be maintained then full HPI flow should be restored.
5.
During this period the operator should maintain at least one reactor coolant pump operating in each loop.
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l 6.
If the operator is unable to accomplish subcooled conditions in the RCS l.@
with full HPI flows within 20 minutes he should assure that a smaller
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. r reactor coolant system boundary, leak exist and he should take the following' f
actions:
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If the location of the leak can be identified and isolated this action t
should be taken. Success o'f this action would be indicated by successful ability to repressurize the system and maintain subcooled conditions.
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8 b.
The operator should manually raise the OTSG water levels on both 95 on the operating range and he should observe cooldown rate limits r
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.(not to exceed 100 /hr) and nil ductility transistion temperature limits while filling the generator. This action will assure higher OTSG levels
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'in case reactor coolant pump power is interrupted for any reason c.
The operator should proceed with RCS cool-down utilizating the OTSG's -
i at rates not to exceed 1d0 /hr' to the point where DHRS operation in the recirculation rode can be initiated. He should initiate DHRS I
operation before securing RCP.
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TRANSIENT TO NATURAL CIRCUt'ATICN In any op'erational evolution inclu' ding the above in which the operator wishes to attempt a transition to natural circula. tion he should take the following
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actions before securing the lost RCP in either loop.
1.
Using auxiliary feedwater thru the auxiliary feedwater nozzles', manually r
raise steam generator levels (both generators) to 95' on the operating range. Observe cooldown rate li:::1ts and NDT limit while filling generators.
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p TRMISIENT TO NATURAL CIRCULATION L, gg 0
2.
Assuring that loop coolant is at least 50 F subcooled (by reducing temperature or raising pressure as required). If this cannot be accomplished pumps should not be secured; in that case proceed with p
emergency cooldown and establish decay heat removal system as suggested above.
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