ML20008F450
| ML20008F450 | |
| Person / Time | |
|---|---|
| Site: | 05000000 |
| Issue date: | 07/22/1981 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| References | |
| IEC-81-12, NUDOCS 8103300406 | |
| Download: ML20008F450 (2) | |
Text
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6830 Accession No.:
8103300406 IEC 81-12 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGf0N, D.C.
20555 July 22, 1981 IE Circular No. 81-12:
INADEQUATE PERIODIC TEST PROCEDURE OF PWR PROTEC SYSTEM Description of Circumstance. :
On November 30, 1980, ground isolation procedures were being carried out to locate an electrical ground in the 125V dc bus No.1 at the St. Lucie Nuclear Power Plant.
to the reactor trip circuit breakers (TCBs).Part of the procedure requires These breakers are desi trip (fail safe mode) on undervoltage upon loss of de control power. gned to to Figure 1, the four TCBs (TCB 1,3,5, and 7) that are supplied control power Referring from dc bus No. 1 did not trip immediately (because of binding) on undervolta when control power was deenergized.
trip for each of the four TCBs was functioning.The operators did verify that the shu the redur. dant TCBs from dc bus No. 2 (TCB 2,4,6, and 8) tripped on similarOpe undervoltage conditions, and, in fact, inadvertently caused a plant trip while testing.
Investigation into the problem by the licensee identified the cause of failure as an out of-adjustment condition in the linkage mechanism of the undervoltage trip device.
This adjustment problem, together with the lack of of IE Bulletin 79-09 which was issued Aprilcleaning and periodic re 17, 1979.
While shutdown, the and verified to operate satisfactorily.undervoltage trip mechanism on periodic test procedure in use at the time did not verify t the undervoltage trip coil independent of the shunt trip coil.
Figure 1, it can be seen that during a reactor trip test at this facility Referring to these coils operate simultaneously causing the trip opening of the associated TCBs.
for other PWRs.This arrangement of the RPS and the trip test procedure may be similar BWRs may use similar circuit breakers in safety tj:tems; therefore, similar indequacies in their circuit breaker test procedures may exist.
Following adjustment of the linkage mechanism of the undervoltage trip device the licensee instituted a revised surveillance test procedure to check the under-voltage and shunt trip devices independently and to insure proper breaker operation.
Although not shown in Figure 1, the undervoltage trip coil and the shunt trip coil are separately fused so that test procedure changes resolved the problem at St. Lucie.
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IEC 81-12 July 22, 1981 Page 2 of 2 Recommended Action for Holders of Operating Licenses and Construction Permits:
It is recommended that holders of operating licenses and construction permits review for applicability the specific items presented in the " Description of Circumstances."
It is further recommended that the procedure for surveillance testing of trip circuit breakers be reviewed and revised as necessary to provide independent testing of each trip function, including position verification to ensure that the breaker actually trips.
If the trip circuit breakers do not have provisions for independent testing of each trip function,. including position verification, then appropriate modifi-cations should be made to include such features (e.g., local pushbuttons for the shunt and undervoltage trip coils, separately fused circuits for the shunt i
and undervoltage trip coils, etc).
No written response to this circular is required.
If you need additional information with regard to this subject, please contact ine director of the appropriate NRC Regional Office.
Attachments:
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SSINS N3:
6870 Accession No:
8103300379 IN 81-18 UNITED STATES NUCLFAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 June 23, 1981 IE INFORMATION NOTICE NO. 81-18:
EXCESSIVE RADIATION EXPOSURES TO THE FINGERS OF THREE INDIVIDUALS INCURRED DURING CLEANING AND WIPE TESTING OF RADI0 ACTIVE SEALED SOURCES AT A SEALED-SOURCE MANUFACTURING FACILITY
Purpose:
This notice provides information about the potential for high radiation exposures, particularly to fingers or hands, while cleaning or wipe-testing multicurie sealed sources.
It is also intended to inform other individuals that have hand contact with radioactive materials of the potential for high exposures to the hands.
This information should be brought to ti.e attention of all persons involved in the administration and operation of sealed-source manufacture, sealed-source use, or ot',er programs which involve hand contacts with radioactive materials.
D_escription of Event:
Three individuals employed at a radioactive sealed-source manufacturing facility received excessive radiation exposures to their fingers.
The exposures were of a chronic nature, extending over several years for two of the individuals.
The highest exposures appeared to have occurred to the right thumbs and index fingers. This is based on the degree of visible radiation injury.
The exposures to the individuals were estinted tc have been 1,000, 7,000 and 25,000 rads respectively during 1980.
The individuals were involved in the cleaning and wipe-testing of rrulticurie sealed sources.
The sources were placed into a "J" shaped cavity in a shielded pig.
The sources were then lifted, lowered,.and rotated by' hand against pipe cleaners that were also inserted into the cavity.
During the lifting procedure, the source was lifted from the bottom of the "J" cavity into an unshielded position.
This resulted in a high-intensity pencil-like beam of radiation out of the cavity.
The excessiv4 exposures resulted because inadequate protective procedures and methods were used.
Failure to perform adequate surveys and failure to provide adequate finger monitoring devices prevented discovery of the exposures until there were visible symptoms of radiation injury to the fingers.
No written response to thi: information notice is required.
If you need addi-tional information regarding this subject, contact the director cf the appro-priate NRC Regional Office.
Attachment:
Recently issued IE Information Notices
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