ML19345A518
| ML19345A518 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 06/19/1974 |
| From: | Autio H YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML19345A517 | List: |
| References | |
| AO-50-29-74-2, NUDOCS 8011240107 | |
| Download: ML19345A518 (3) | |
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AB:;0RMAL OCCURRElCE REPORT REPORT !U"IiER:
50-29/Th-2 REPORT DATE:
June 19, 197h OCCURRE' CE DATE: June 16, 1974 FACILITY:
Yankee Atomic Electric Company, Bove, Massachusetts IDEIITIFICATIO:I OF OCCURRE: ICE:
Containment Isolation Actuation System Setpoint Drift.
CO:lDITIO:!S PRIOR TO OCCURRE:!CE:
Refueling Shutdown, Shutdown Cocling System Operating, Reactor Coolant Temperature at 100 F.
DESCRIPTIO: OF OCCURRE: ICE During routine refueling interval surveillance testing of the Containment Trip Valve Isolation System, Procedure OP-4610, VC Trip Valve Test and Pressure Switch Calibration, one of the two identical pressure switches, PS-231, used to trip the system operated at 5.3 psig. Also, during the same test, the con-tainment air particulate monitor sample lines isolation system pressure switch operated at 7.0 psig. This is a violation of Technical Specification Section D.2.e.8 which lists a maximum setpoint of 5 0 psig.
DESIG: ATIO: OF APPARE!;T CAUSE OF OCCURRE!!CE PS-231 was set too close to the technical specification limit and normal instrumentation drift caused exceeding the limit.
The vapor container air particulate sample lines isolation system pressure sviteb's out-of-tolerance setpoint was also due to setpoint drift. The magnitude of the out-of-tolerance value (2 psi) is apparently due to the pressure switch having too great n ; pan for its intended use.
A!!ALYSIS OF OCCURRE:CE, PS-231 is one of two identical pressure switches (the other being PS-230) us2d to trip the Containment Isolation System.
If the containment pressure reaches 65 psic this system automatically closes 27 trip valves in the vapor container outgoing lines used for the operation of the plant.
PS-230 operated at <5 psig during the above referenced test, and therefore if containment isolation vere required because of a LOCA the 27 trip valves vould have tripped below the technical specification limit.
The vapcr container air particulate monitor has its own system for isolating the two one-inch sampling lines. The two sample lines terminate in a sealed hcusing containing the air particulate paper drive mechanisms and detector.
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The Beactor Containment Pressure Analysis, YAEC FHSR Section hl2 shows that during a LOCA vapor container pressure peaks out at 31.6 psig within 18 seconds. This pressure transient greatly exceeds the out-of-tolerance values of 5.3 and 7.0 psig.
It can therefore be concluded that vapor con-tainer isolation valves would have all closed during a LOCA and exposure to personnel and radioactive material release would not have taken place because of the out-of-tolerance setpoints thus resulting in no additional risk to public health and safety.
CORRECTIVE ACTION The containment isolation actuation system pressure switch, PS-231, was readjusted to operate at h.4 psig.
The containment air particulate sample lines isolation pressure switch was i.lso readjusted to <5.0 psig.
In the near future it will be replaced with a new pressure switch having a narrower span.
FAILURE DATA N/A 0
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DATIdFD0C DATE REC'D LTR TWX RPT CTIER 7
.1 Ycnkee Atomic Electric Company
/
Rowe, Mass. 01367 6 - 1 9 - 74 6-27-74 X
H.,A. Autio ORIG CC OTIER SENT AEC PDR X
T02 J. P. O'Reilly 1 signed SDiT LOCAL PDR CLASS U: CLASS PROP INFO INPUT NO CYS REC'D DOCKET NO:
50-29 1
yy,yy, ENCLOSURES:
DESCRIPTIC:i:
Ltr trans the following:
A0 50-29/74-2: Reporting abnomal occurrence on 6-16-74, regarding containment isolation actuation system setpoint drift.
'A.CKNOWLEDGED DO NOT REMOVE PLANT NAFZ: Yankee
( 1 cy rec'd )
FOR ACTIC:;/I! ?C l'_t. TIC" 7-1-74 GC BUTLER (L)
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