IR 05000261/1980027
| ML14175B213 | |
| Person / Time | |
|---|---|
| Site: | Robinson, Brunswick  |
| Issue date: | 10/21/1980 |
| From: | Gibson A, Wray J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML14175B212 | List: |
| References | |
| 50-261-80-27, 50-324-80-36, 50-324-80-39, 50-325-80-39, NUDOCS 8012090210 | |
| Download: ML14175B213 (5) | |
Text
,,bkREGU UNITED STATES NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTA ST., N.W., SUITE 3100 ATLANTA, GEORGIA 30303 Docket Nos. 50-325/80-39, 5-324/80-36 and 50-261/80-27 Licensee:
Carolina Power & Light Company 411 Fayetteville Street Raleigh, NC 27602 Facility Name: Harris Energy and Environmental Center License Nos. DPR-71, DPR-62, DPR-23 Inspection at New Hill North Carolina Inspector:
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-1 fV Wray Date Signed Approved by:
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(lN 11o A. F. Gibson Date Signed Inspection on September 4, 1980 Areas Inspected This special, announced inspection involved 8 inspector-hours at the Harris Energy and Environmental Center reviewing the circumstances surrounding recent erroneously recorded personnel exposures for the Brunswick and H. B. Robinson Facilitie Results Of the one area inspected, no apparent items of noncompliance or deviation were identifie DETAILS Persons Contacted Employees B. Webster, ManagerRadiasime and Environmental Control S. Browne) Supervisor-.Dosimetr Exit Interview The inspection scope and findings were summarized on 9/4/80 with those persons indicated in Paragraph I abov The p rogram manager stated that the licensee's immediate interim corrective actions to preclude recurrence of TLD reader calibration discrepancies will include:
) tighter quality control on each TLD anneal batch, 2) more frequent TLD reader calibration checks, and 3)
immediate and thorough investigation of any TLD readers found out of calibration. The inspector stated that pending the licensee's determination of final corrective actions, this issue will be considered Unresolvedi Licensee Action on Previous Inspection Findings Not inspecte Unresolved item Unresolved items are matters about which more information is required to determine whether they are acceptable or may involve noncompliance or deviations. A new unresolved item identified during this inspection is discussed in paragraph.
Sequence of Events On July 25, 1980, a batch of between 500 and 1000 thermoluminescent dosimeter8 (TLD) were annealed at the Harris Energy and Environmental Cente Carolina Power and Light (CP&L) maintains a supportive personnel and environmental dosimetry program for its Brunswick and H. B. Robinson nuclear power facilities at the center including four TLD readers, an irradiation facility, equipment repair facilities, two TLD annealing ovens, and badge preparati on production facilities. On August 1, 1980 several TLD's from this batch were irradiated to 501 mrem'and, on August 4, used to check the calibration of TLD readers #1 and #4. On this date several additional TLD's from the batch were irridated to 523 mrem and used the next day to check the calibration of TD readers
- 2 and #3, which was at the H. B. Robinson facilit o All readers failed their respective calibration checks; all four had consistently indicated doses 30% to 40% greater than the known irradia tion value. Procedure RC-PD-4 stipulates that the average backgrond-
-2 corrected calibration reading must be within +/-15% of the known irradia tion value to meet acceptance criteri As per section 8. of procedure RC-PD-4, all readers were removed from service and recalibrated in accordance with procedure RC-PD-1 Reading July's TLD badges from Brunswick began on August 5 using the recalibrated reader Recalibrated reader #4 was shipped to Brunswick on August 7 to facilitate processing of outage TLD badges. A few days later, recalibrated reader #2 was shipped to the H. B. Robinson plant to facilitate TLD processing. Calibration checks were performed on the readers in the-field using chips from thek previously mentioned annealed batch and all readers responded within acceptable limit A subsequent calibration check of TLD reader #4 at the Brunswick site with a different irradiation TLD source chip indicated an unacceptable low value. The reader was removed from service and returned to the Energy Center for further investigatio At the Energy Center, the licensee checked for a potential problem with their irradiation facility by irradiating the calibration check TLD to 20 R. The TLD reader correctly processed this dat The licensee then reannealed the calibration check TLD, reirradiated it to 20 R and discovered that the reader was approximately 35% low in its reported valu The licensee immediately recalibrated TLD reader
- 4 and #3, which were in-house,' and sent reader #4 to Brunswick. The readers in the field were retrieved for recalibratio The licensee traced the problem with the calibration check TLD to the anneal cycle performed on July 2 On August 29, the licensee informed the NRC that problems with their TLD readers had resulted in occupational exposure readings to be 30% to 40% low for all badges read between August 5 and August 24 for the Brunswick Steam Electric Plant and from August 11 for the H. B. Robinson facilit.
Records Review An inspector reviewed the methods used to compute correction factors which were applied to exposure readings obtained between August 5-2 For TLD readers #1 and #4, ratios of reference light values (RLV)
recorded prior to and subsequent to the recalibration on August 4 produced identical correction factors of 1.3 Since TLD reader #2 had filter maintenance work performed during this time, a ratio of RLV would have been inappropriat A ratio was established between a known check TLD calibration chip irradiation value and the average background-corrected reading obtained from the reade Thusly, the correction factor for TLD reader #2-is 1.4 NoTLD badges were processed by reader #3 between August 5-24, therefore, calculating a correction factor was unnecessary. The inspector concluded that the correction facto'rs were properly compute. The licensee applied the correction factors to the recorded occupational exposure readings processed between August 5-24 and stated that no overexposures had occured. Since daily work assignments and stay time
-3 are based on pocket dosimeter readings, no overexposures were expecte However, a review of exposure records showed a number of close call An inspector at the Brunswick site observed that no formal, written comparison is performed when pocket dosimeters and TLD badges differ by more than 25% through an informal review appears to be required by procedure 0200, Attachment The TLD value was recorded as the accurate exposure in each case questioned even when the pocket dosimeter reading was greater. This has resulted in an item of non-compliance against the Brunswick facilit However, the on-site inspector found no irregularities in the licensee's application of the TLD reader correction factors and concluded that no overexposures had occurred due to the initial low readings of TLD badges (see NRC RII report no 50-325/80-36; 50-324/80-33). Futhermore, the inspector had no further questions concerning the application of correction factors to exposure data at the Harris Energy and Environmental Cente.
Procedure Review An inspector reviewed Harris Energy and Environmental Center procedures RC-PD-1 thru RC-PD-14 which form the Dosimetry Laboratory Instruction Manua Procedure RC-PD-4 limits acceptable stability checks to within +1% of the reference light value established during calibration and acceptable calibration checks to within +15% of the known irradiation value. Stability checks are performed daily prior to use and hourly during use of the TLD reade Calibration checks are performed at least monthly or following any maintenance performed on the unit. The inspector noted that these limits and frequencies meet present day acceptance standard Procedure RC-PD-11 addresses the calibration of the licensee's LiF chips and the Teledyne 7300 TLD reader Irradiation fields are measured with Victoreen R Chambers referenced to the National Bureau of Standard A chip is accepted for use if it responds to within
+/-10% when exposed to 500 mrem irradiations using a Cs-137 source. The inspector had no further questions concerning the licensee's irradiation and chip acceptability practice Calibration check source chips are produced by irradiating 10 chips and averaging their responses to a known exposure valu The inspector stated that averging 10 irradiated chips out of 500 to 1000 annealed chips will not result in statistically accurate value The licensee stated they will review this item in more detai The procedures also state that the calibration chips are irradiated to approximately 500 mrem. The inspector stated that this assumes TLD reader linearity and that irradiation levels encompassing the entire range of potential exposures, including accident exposure levels, should be incorporated into the reader calibration checks on some regular basi Procedure RC-RD-2 covers the preparation of TLD badges, including cleaning, annealing, labeling, and loading of TLD badge CP&L possesses approximately 16,000 teflon-impregnated LiF TLD chip It is important for cleaning, labeling, and loading of chips to be consistent for each chip to insure uniformity. Annealing is performed on a batch basis in special programmed ovens. Since only 500 to 1000 chip can be annealed at one time, it is extremely important to maintain temperature and time controls consistent from batch to batch as the annealing process affects the TLD sensitivity to radiation A TLD annealing log is maintained for this purpose where times and identi fication numbers are entere Special attention is placed on the cooldown time which is the most sensitive part of the procedure. Even small changes in cooldown rates can alter chip sensitivities by a measurable amoun On July 25, the cooldown rate and anneal start and end times were not recorded as required by procedure RC-PD-It appears that problems with TLD readers are related to TLD chips used for their calibrations obtained from the anneal batch of July 25. The licensee stated that the investigation into the exact cause within the anneal cycle is continuing and in the interim, 1) tighter Quality Control will be initiated on each TLD anneal batch, 2) more frequent TLD reader calibra tion.checks will be performed, and 3) immediate and thorough investiga tions of any TLD reader found out of calibration will be carred ou The inspector stated that pending the formulization of final corrective actions by the licensee, this item will be considered unresolve (50-325/80-39-01; 50-324/80-36-01; 50-261/80-27-01) The inspector noted that procedures requiring reader recalibration when certain acceptance limits are exceeded imply that all problems associated with the improper reader response are due to reader manfunctio The inspector stated that changes to applicable procedures should be considered to include investigations of the irradiation and/or annealing facilities as potential reasons for unacceptable reader response. A licensee representa tive infromed the inspector of a procedure review that had been initiated and will be applied to the Dosimetry Laboratory Instruction Manual in the near futur This review program will make change recommendations were appropriate. The inspector cautioned the licensee representative that such a review must follow appropriate channels as the Harris Energy and Environmental Center's dosimetry procedures are required by the Technical Specifications for the Brunswick and H. B. Robinson plants. The licensee representative acknowledged this comment.