ML051460505

E-Mail from Karjala (Riii) to Alexander (Riii) Update on Westinghouse Dose-Rate Alarm Incident

ML051460505
Person / Time
Site:	Point Beach
Issue date:	04/14/2004
From:	Karjala D NRC/RGN-III
To:	Ryan Alexander NRC/RGN-III
References
FOIA/PA-2004-0282
Download: ML051460505 (4)

Text

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Ryan Alcxander - Re: Update on Westinghouse Dose-rate Alarm Incident Pawe 2 a Duane Ryan D. Alexander Radiation Specialist - Reactor U.S. Nuclear Regulatory Commission, Region IlIl Office: 630-829-9853 Fax: 630-515-1249 E-mail: rda~nrc.iov CC: Morris, R. Michael

Evaluation of workers not receiving electronic dosimeter alarms while working in dose rate fields higher than the alarm setpbint.

Condition On 4/14/2004 at approximately 0340 a Westinghouse worker reached into a dose rate field that exceeded the alarm setpoint on his electronic dosimeter. (RADOS) The entry only lasted sevetal seconds. The worket was installing'equipment in the B SfG'to support eddy-current testing. Neither the worker nor the RP'technician covering the job heard an alarm. Additionally, the TeWdiew tkansmitting dosimeter (MGP) did not send an alarm signal to the Teleview monitor that the RPT was watching. The fact ihat the ED had registered' a dose rate greater.than the alarm setpoint was noticed upon review of entry/exits in the access control software.

ACS was reviewed after anotherworkerreceived a dose rate alarm on theirRADOS ED while installing equipment in the B S/G to support eddy-current testing. Both the'RPT, and the worker heard this alarm and responded approTpriately. When the second worker was hoted to have a dose rate alann the Teleview monitor read 1500 mR/hr. This alarm occurred at approximately 0416.

The alarm setpoint for both workers was 2500 .mR/hr.

RADOS EPI) Max Rate MGP ED Max Rate Worker l 2841 irhil 3870 MR/hr Worker2 2840 niRhr 3100 mRhr Evaluation The following actions were taken:

• The RADOS ED (981647) was satisfactorily:tested to make sure that the speaker works. The ED also showed n6 errors in thebiauiual reader.

• The Westinghouse worker was questioned and reported that they did not hear an ED alarm.

• A transmitting dosimeter was tested in the S/G channelhead to ensure radio contact was being maintained. This was completed satisfactorily. The lowest signal strength seen was eight on a scale of one to fifteen. Dose rates seen by the dosimeter were 4800-5600 mR/hr inside the S/G channelihead.

• The MGP vendor was contacted. He suggested that we check. the configuration and threshold of the teledosimeters. This was completed with no issues noted. The vendor was asked if it was possible that the alarm condition could have come and gone so quickly that it would not have been transmitted. He didn't know for sure but said that you would see a dose rate spike on the histogram,. A dose rate spike was noted on the histogram corresponding to the alarm'condition ftom 03:39:41 to 03:39:45. Max dose rate seen was.3870 rnRlhr.

Conclusion The Westinghouse workers were making hand entries into the S/G channelhead that only lasted several seconds. The likely reason that no alarm was received .n either the RADOS ED or the MGP ED was that the entry time was so short that although both electrom'c dosimeters registered dose rates higher than the alarm setpoint they had been removed:from the dose field beforelthe alarm activated.

The primary means of dose control for-ECT of the S/G's is timekeeping. The Teleview system is a backup and aid to the job coverage RPT. The RWP was. teriminated and a new RWP written with higher dose rate alarm setpoints that meet the actual conditions in the SIG.

Neither worker received a dose alarm or exceeded the dose allowed by the RWP.

Pefmission to proceed with the job was obtained from the RPM and Engineering Director at approximately 2100,4/14/2004.