ML19322A929
| ML19322A929 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/11/1975 |
| From: | Thies A DUKE POWER CO. |
| To: | Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| Shared Package | |
| ML19322A925 | List: |
| References | |
| NUDOCS 7911270813 | |
| Download: ML19322A929 (2) | |
Text
DUKE POWER COMPm Powru Burt_onto can Sourn Gn uncit SrnzzT, Cn AntoTTz, N. C. arso:
'N
]
A. C THets P. O. Dox 2 7e
$ swoon vict Per se r =7 PeCCutflON AND Tm a n g ne i% S.0 %
J **
April 11, 1975 Mr. Norman C. Moseley, Director U. S. Nuclear Regulatory Co==ission Suite 818 230 Peachtree Street, Northwest Atlanta, Georgia 30303 Re:
IE:II:TNE 50-269/75-1 50-270/75-1 50~287/75-1
Dear Mr. Moseley:
The purpose of this letter is to provide additional information regarding iten I.B.3, " Personnel Radiation Exposute Records," of IE Inspection Report 50-269, -270, and -287/75-1.
The following discussion provides the justification for reducing the exposure records of two individuals and not similarly reducing the records of all other personnel when a possible error in TLD desitetry results was discovered.
l Ihe method of deternining the day-to-day radiation dose to personnel at Oconee Nuclear Station is through the use of personnel dositeters.
In addition, TLD badges are worn by personnel and are processed, generally conthly, to provide'a more accurate, after-the-fact, deasurecent of dose received.
In general, dositeter results are higher than TLDs, and hence this is a conservative practice.
The results of the TLD are transcribed to the personnel exposure records as they are received frc=
the TLD service contractor.
On January 16, 1975, radiation dose information was supplied by the TLD vendor uhich indicated that two centract personnel had been exposed above 100 CFR 20.101 limits during the fourth quarter, 1974.
The spacific values of dose reported by the TLD vendor were 3040 and 3410 nilliren.
This dose was not consistent with dositeter results which were much less than 3 ren.
Additionally, one of the individuals had worn a filn badge, supplied by his employer, which indicated that he had caly received a dose of 2100 milliren during the quarter.
His dosiLeter was in substantial agreement with this film badge.
Subsequently, a letter received from the TLD vendor described uncertainties in the TLD results and concluded that fourth quarter TLD readings had been reported as 15 percent to 30 percent high.
gp ava4 P/3 1
T Mr. Norman C. Moseley Page 2
(
April 11, 1975 As a result of this evidence, t$b individual previously thought to have received a dose of 3040 millirem was assigned an exposure of 2110 millirem based upon his film badge and dosimeter readings.
The second individual, previously thought to have received a dose of 3410 millirem was assigned an exposure of 2965 millirem based upon his dosimeter readings and a TLD correction factor of 15 percent.
The records of all other personnel were not similarly reduced because there is no methed of accurately determining the specific error as.eociated with each individual TLD.
It would not be correct to apply an across-the-board correction factor to all records since C e accura.
I the dosimeter totals for each individual could not be determlaed and there was no ad-ditional supporting evidence of the most likely dose that should be assigned each individual.
The exposure data which is currently recorded, based on the uncorrected TLD results, is greater than actually received.
This is a conservative method of dose assignment in accordance with long-standing health physics practice.
The net effect of this practice is to unnecessarily limit the maintenance activities of the station in order to ninimize the indicated personnel exposure.
Duke Power Company is aware of, and is working to solve the problem of inconsistencies between dosimeter and TLD results.
Very truly yours, A. C. Thies ACT:vr H