ML20064L446
| ML20064L446 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Brunswick |
| Issue date: | 06/04/1982 |
| From: | Wolf T NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Rubin S NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| Shared Package | |
| ML20064E577 | List: |
| References | |
| FOIA-82-389 NUDOCS 8206220591 | |
| Download: ML20064L446 (5) | |
Text
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UNITED STATES
$g*h'Q.
,,E NUCLEAR REGULATORY COMMISSION 3
o WASHINGTON, D. C. 20555 o i f '. (* #
.9 JUN 4 1982
~
MEMORANDUM FOR:
Stuart Rubin 0ffice for Analysis and Evaluation of Operational Data FROM:
Thomas R. Wolf Office for Analysis and Evaluation of Operational Data
SUBJECT:
TELECON NOTES - CONV'ERSATION WITH CAROLIP POWER AND LIGHT PERSONNEL CONCERNING JANUARY., 1982 LOSS OF RESIDUAL HEAT REMOVAL SERVICE WATER EVENT AT BRUNSWICK STEAM ELECTRIC PLANT - LER 2-82-005/0lT
Participants:
NRC - AEOD CP&L/8SEP NRC - Region II S. Rubin J. McQueen, Jr.
D. Myers - Senior Resident M. El-Zeftawy M. Grim Inspector T. Wolf G.'Th apson M. Chiramal R. Poulk F. Ashe
Background
Brunswick Steam Electric Plant (BSEP) Unit 2 reported in Licensee Event Report (LER) 82-005/01T that on January 16, 1982 an unsuccessful attempt was made to initiate normal suppression pool cooling via the residual heat renoval (RHR) system. This try came following a sequence of occurrences which-included a turbine trip, a reactor scram, a loss of normal feedwater, and a reactor core isolation cooling (RCIC) system initiation.
Normal suppression pool cooling (as well as normal shutdown cooling) could not be attained because both residual heat removal service water (RHRSW) trains were inoperable. These RHRSW trains were inoperable since none of the four booster pumps (two pumps per train) could be started.
In the LER l
the reasons given for these pump start f ailures were:
" Low suction header pressure lockout signals in each loop prevented starting each loop's pumps.
Plugging of the sensing line to each loop's suction header pressure switch prevented both switches from sensing actual pressure, although a lack of l
operating fluid in the A. switch and an open power supply l
breaker to the B switch _also would have prevented pumps from startirig.E'
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Stuart Rubin.
't Normal cooling of the reactor by utilizing main feedwater steaming to the condenser was restored within a half-hour of the sequence initiation.
After maintenance and testing, RHRSW "B" train was declared operation ~al within 4.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> of the sequence start and "A" train within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
At no time during this event were any saf6ty parameters challenged.
Highl ights 1
Sequence SEQUENCE OF OCCURRENCES Time
' Description (approximate)
~
J anuary 16, 1982
< 1625 Reactor power 0100%;
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Steam jet air ejectors (SJ.AE) develop
' troubl e; Condenser vacuum decreases; Power reduction initiated.
> 1625 One set of SJAE lost.
1632 Select rod insert cannanded.
1633 Reactor power 030-40%;
Low condenser vacuum; Turbine stop valve f ast closure; Reactor scram.
l 1638 Group 1 isolation (main steam isolation valves /~MSIV7 close);
Main feeddter flow lost.
1640 RCIC manually started with suction from condensate storage tank; Suppression pool temperature @ 730 - 740F; Drive steam. to RCIC tut bine maintains reactor coolant system (RCS) pressure; Per plant procedures, operator attempts to initiate RHR suppression pool cooling by starting "B" train of RHRSW; RHRSW "B" train booster pumps suction header pressure switch PS-1176 low pressure alarm
( < 20 psi);
L._
Stuart Rubin 3-RHRSW "B" train booster pumps (B and D) prevented from starting by low suction pressure interlock; Operator attempts to start "A" train of RHRSW; RHRSW "A" train booster pumps suction header pressure switch PS-1175 low pressure alann ( < 20 psi);
RHRSW "A" train booster pumps (A and C) prevented from starting by low suction pressure. in terlock; Control panel booster pump suction pressure indicted 0 60 psi; RHRSW declared inoperable; Maintenance request initiated.
1650 Condenser vacuum restored; Group 1 isolation signal reset; MSIV reopened.
1655 Reactor feed pump started re-establishing feedwater flow; RCIC secured; 0 750 - 76 F.
0 Suppressicri pool temperature 1710 Technician discovers PS-1176 power feed 120v-ac breaker open; Breaker manually closed; RHRSW "B" train booster pump interlock autcrnatically clears;'
RHRSW "B" train booster pumps started and associated RHR train aligned and operated in suppression pool cooling. mode.
1810-2040 RHRSW "B" train cycled on and off several times to run further operability tests.
2040 RHRSW "B" train declared operational.
- Janua ry 17, 1982
~
0025 After maintenance and testing, RHRSW "A" train declared operational.
(PS-1175.
repai red.
Failure due to leakage of operating fluid in diaphragm housing.)
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. Stuart Rubin Pertinent Operational Items Plant procedures at BSEP require the start of suppression pool cooling after any RCIC initiation no matter what the circumstances causing RCIC 1.
Th,us, the attenpt to start or what the suppression p6ol temperature.
start. suppression pool cooling in this case was not in itself indicative of an actual or urgent need to accomplish this task or of a serious event occurring which required such cooling.
For cases where normal RHRSW is lost and RHR cooling is required, 2.
several alternatives are given in the pl, ant operational guidelines.
~
These are:
tilizing
. Supply the RHR heat exchangers (RHRHX) from the SW system u only the dain SW pumps without the use of the RHRSW a.
all heat renoval requirements via this method; however, the SW-to-reactor water positive differential pressure across the RHRHX for radioactive fluid outleakage control will be lost.
Utilize available manual conne'ctions between the SW and the fire b.
The fire protection pumps develop sufficient protection system. head and flow rates to replace the SW but this. source The fire protection storage by its water supply storage capacity. gallon minimum technical specific supply consists of a 200,000 volume in a dedicated 300,000 gallon capacity tank and a connection to the 90,000 gallon minimum technical specification volume in the 150,000 gallon capacity demineralized water storage tank.
l At low RHR heat removal rates, utilize available RHR connections to c.
the spent fuel cooling heat exchangers..
Service water system cross connects between units _are not included in Therefore, at BSEP, this potential cooling d.
the BSEP system design.
method is unavailable.
In this event, the need for RHRSW was minimal and, consequently, none.of the alternative cooling methods were utilized.
Event Causes and Corrective Actions Investigations into the causes and corrective actions for this. event conce on the pressure switches, circuit breaker, and starting interlock.-
=
l
,'.s Stuart Rubin.
1.
Pressure switch:
It was determined subsequently to the data utilized to write LER 82-005/0lT that silting was not a contributing factor ~in the failure of the pressure switches.
The pressure switch failures were due to (a) an open power circuit" breaker to 'one switch and (b) the loss of oper.ating fluid within the other pressure switch. A study is being conducted to see if this pressure switch type is susceptible to this type of fluid loss failure and to see if some other type of pressure switch is available to replace these switches.
2.
Circuit breakers:. Functional. testing.of the subject circuit breaker and associated circuits revealed no abnonnalities. As a precaution, the breaker was replaced with an identical unit.
It was determined, however, that the particular circuit breaker involved is designed such that it cannot be readily determined upon visual inspection whether
.the breaker is in the tripped or untripped position. ~ Since this is a comonly used breaker in the plant, consideration is being given to replace all such breakers with ones giving more noticeable position indication.
From a human factors viewpoint, such a modification would improve the operational as well as safety security of the affected systems.
3.
Booster pump interlock logic: The present interlock design is such that one pressure switch.is supplied in each RHRSW booster pump train and this switch controls the starting of both of the booster pumps in its respective train. Consideration is now being given to modify this logic by:
a.
Adding a redundant pressure switch in each loop; b.
Adding suction valve position indication into the circuitry; c.
Deleting the suction pressure interlock but replacing it.with a valve position interlock.
While' these studies continue, BSEP personnel have ordered a supply of the presently utilized pressure switches. Maintenance personnel are being instructed to simply change out any switch if problems develop. Testing has shown that this change out takes about 20 minutes. As a last resort, the interlock may be jumpered cut. This procedure takes about 5 minutes.
zgA2 Thomas R. Wolf Office for Analysis and Evaluation
'of Operational Data cc:
J. McQueen, Jr.
R. Poulk
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