IR 05000317/1979018
| ML19296B122 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 11/20/1979 |
| From: | Stohr J, Yuhas G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML19296B106 | List: |
| References | |
| 50-317-79-18, 50-318-79-15, NUDOCS 8002200105 | |
| Download: ML19296B122 (10) | |
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U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT
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50-317/79-18 Report No. 50-318/79-15 Docket No. 50-317 50-318 arr.-aa License No. DPR-69 Priority Category CC
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Licensee:
Baltimore Gas and Electric Company P. O. Box 1475 Baltimore, Maryland Facility Name:
Calvert Cliffs Nuclear Power Plant, Units 1 and 2 Inspection at:
Lusby, Maryland Inspection conducted:
October 3-5, 1979
//!20
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Inspectors:
s G.
Vufias, Rad'iation Specialist
/date signed date signed date sign d Approved by:
//
2o
J.P/Stohr, Chief,RadiationSupportSection date signed'
Inspe: + ion Summary:
Inspection on October 3-5. 1979 (Combined Inspection Report No. 50-317/79-18; o0-318/79-15 Areas Insoected:
Special, unannounced inspection by a regional based inspector of areas of the radiation protection program including:
noble gas exposure and dosimetry discrepancy evaluations. Upon arrival at 4:00 p.m., October 3, 1979, areas where work was being conducted were examined to review implementation of radiation safety practices and procedures. This inspection involved 16 inspector-hours on site by one NRC regional based inspector.
Results:
Of the two areas inspected, one item of noncompliance was identified in one area, (Infraction - failure to adhere to radiation protection procedure RCP3-310 as required by Unit 1 and 2 Technical Specification 6.11, Paragraph 4).
8002200 ( 0 9
\\
Region I Form 12 (Rev. April 77)
DETAILS 1.
Persons Contacted
- L. B. Russell, Chief Engineer
- A. J. Kaupa, Radiation Safety and Chemistry Engineer R. Denton, Nuclear Plant Engineer, Operations E. T. Reimer, Plant Health Physicist
- J. T. Carlson, Radiation Safety and Chemistry Foreman The inspector also interviewed other licensee and contractor personnel including members of the Radiation Safety and Maintenance staffs.
- denotes those present at the exit interview conducted October 5, 1979.
2.
Background On September 27, 1979, NRC Region I was contacted by a worker who expressed concern regarding the licensee's evaluation of dosimetry discrepancies involving dose as measured by self reading and thermoluminscent dosimeters.
On September 29, 1979, NRC Region I was contacted by a different worker who expressed concern with the adequacy of the licensee's dosimetry devices for measuring dose from Xenon 133 and 135 concentrations present during containment entries.
Neither worker requested an inspection pursuant to 10 CFR 19.16, however, Region I dispatched an inspector on October 3, 1979 to review these concerns and determine licensee compliance with applicable regulations and license conditions.
3.
Noble Gas Exposure The inspector reviewed the following licensee procedures against the requirements specified in Section 6.8 " Procedures" and 6.11 " Radiation Protection Program" of Unit 1 and 2 Technical Specifications.
Name Number Revision General Safety Rules RCP-101
Personnel Dosimetry Scope of Section RCP3-300
Personnel Exposure Control RCP3-301
Requirements for Wearing Thermo-luminscent Dosimeters RCP3-302
Name Number Revision Reading and Reissue of Thermolumin-scent Dosimeters RCP3-304
Source and Drift Check of Self Reading Dosimeters RCP3-305
Determination of Neutron Exposure RCP3-306
Use of Computer Oosimetry Program RCP3-307
Requirements for Usage of Personal Alarming Dosimeters RCP3-308
Personnel Dosimetry Quality Assurance RCP3-310
Operation, Maintenance and Calibration of the Teledyne Isopopes Model 9100 and Model 8300 TLD readers 78-34RCP From this procedure review and from discussions with the Plant Health Physicist, the inspector learned that the licensee has used their thermo-luminescent dosimetry (TLD) system to measure the dose to individuals resulting from exposure to concentrations of radioactive noble gases in air.
Since early 1979, the licensee has been experiencing leakage from a Unit 2 Safety Injection Tank.
This leakage requires makeup to the tank at an average frequency of twice daily.
The tank must then be sampled and analyzed as required by Unit 2 Technical Specification Section 4.5.1.
This sampling is performed inside the containment building on the 45'
elevation.
The sampling is normally performed by radiation chemistry technicians.
Review of licensee survey data indicates individuals collecting these samples with the reactor at power are exposed to gamma radiation intensities of up to 100 mR/hr, neutron radiation intensities of up to 200 mrem /hr and various concentrations of airborne radioactive material The average time required for a radiation chemistry technician to collect this sample is about three minutes.
The inspector reviewed a entry on October 5, 1979, made under Special Work Permit 79-169F to collect the sample and perform an additional minor inspection.
This entry took six minutes.
Three individuals were involved.
Each individual received 8 mR, as measured by self-reading dosimeter, and 14 mrem due to neutron exposure, as calculated from measured neutron dose rate and duration in the area.
The workers were exposed to concentrations of radioactive materials in air 12 times the levels. stated in Appendix B, Table I for the mixture of isotopes present excluding noble gases.
A sample of the gaseous activity was collected at the inspectors request on October 4, 1979, at 8:30 p.m. at the 45' elevation.
The results of this sample are noted below:
Unit 2 Containment 45' Elevation October 4, 1979 2030 Xenon-133 1.59 E-3 uCi/ml Xenon-135 6.7 E-b uCi/ml Xenon-133M 1.7 E-5 uCi/ml Krypton-85M 4.5 E-6 uCi/ml Krypton-88 4.3 E-6 uCi/mi Krypton-87 1.26 E-6 uCi/ml Argon-41 2.29 E-6 uCi/ml Review of previous survey data from the third calander quarter of 1979 indicates the above sample is representative of noble gaseous activity to which workers were exposed during collection of the safety injection tank samples.
Summarized in the table below are the xenon 133 activities measure in containment during this period.
Table I Xenon-133 Activity in Containment Air Date Activity July 2, 1979 1.6 E-3 uCi/ml July 9, 1979 1.0 E-3 uCi/ml July 16, 1979 1.8 E-3 uCi/ml August 6, 1979 8.04 E-4 uCi/ml August 27, 1979 1.32 E-3 uCi/ml September 4, 1979 1.32 E-3 uCi/ml
- September 17-23 8.0 E-7 uCi/ml October 1, 1979 9.7 E-4 uCi/ml
- The reactor was not operating during this perio The inspector reviewed the records of personnel monitoring maintained pursuant to 10 CFR 20.401 for thuse individuals making containment entries to collect the safety injection tank samples during the third calendar quarter of 1979.
Sixteen station and 28 contractor technicians were used to collect these samples.
A total of 2858 mrem of dose due to neutron radiation was recorded.
The highest individual dose for that quarter was 177 mrem due to neutron radiation.
The gamma dose as a result of these entries would have been about 1800 mrem with the grertest dose to any single individual of about 100 mrem.
Review of these personnel exposure records did not indicate any dose to skin of the whole body due to these entries.
10 CFR 20.202 " Personnel Monitoring" requires that each licensee supply appropriate personnel monitoring equipment and require its use by each individual who enters a restricted area under such circumstances that he is likely to receive a dose in any calander quarter in excess of 25 percent of the applicable values specified in paragraph (a) of 10 CFR 20.101.
The licensee uses a 0.4 mm CaS0 :Dy TLD.
The licensee has not conducted
tests to establish the appropridteness of this TLD for monitoring Xenon 133.
From a review of sample analysis, it appears that Xenon-133 consititues more than 90 percent of the airborne radioactive material in the containment air when the reactor is at power.
Xenon-133 emits beta radiation with a maximum energy of 0.346 MeV.
Review of technical data supplied to the licensee by the TLD manufacturer indicates the minimum beta energy sensitivity for and 0.4 mm CaS0 :0y dosimeter is less than 0.4 MeV; however, at this
energy, the dosimetdr under responds.
Test data did not include Xenon-133.
The lowest energy beta respones presented in the data was for Tungsten 185 with a maximum beta energy of 0.43 MeV and average beta energy of 0.14 MeV.
The TLD under responded by a factor of 6.6 to this energy of beta radiation.
The licensee representatives, acknowledged the lack of demonstrated appropriateness of their TLD for use in monitoring the skin of the whole body dose due to Xenon-133 exposure.
However, the licensee representatives demonstrated that no individual involved in these containment entries was likely to have received a dose of 25% of the 10 CFR 20.101 limit of 7 1/2 rem per quarter to skin of the bod The inspector noted that the licensee's procedures do not specifically address situations such as containment entry at power that might result in exposure to high concentrations of noole gas and the dosimetry problems associated from such exposure.
The licensee representatives stated they would revise their procedures to insure appropriate review and evaluation is given to potential skin dose situations.
This revision will be reviewed in a subsequent inspection (50-317/79-18-01; 50-318/79-15-01).
From review of RCP3-310, " Personnel Dosimetry Quality Assurance" and from discussions with licensee representatives, the inspector learned that the licensee does not include a demonstration of beta response in their routine TLD quality assurance program.
The licensee representative stated that they accept the technical data provided by the TLD manufacturer regarding beta exposure.
In addition, since no performance criterion has been imposed on dosimetery services in general, they did not plan to develop their quality assurance program until a uniform standard is implemented.
The inspector noted that since the licensee performs onsite dosimetry and since individuals are at times exposed to beta radiation it is necessary and appropriate that the licensee perform periodic tests to demonstrate the continued " appropriateness" of their dosimetry system for measuring the dose which workers might receive from all sources of radiation to which they are exposed.
The licensee representative acknowledged this need and stated that procedure RCP3-310 will be revised to include a beta quality assurance program.
This revision will be reviewed in a subsequent inspection (50-317/79-18-02, 50-318/79-15-02).
4.
Dosimetry Discrepancies Unit 1 and 2 Technical Specifications, Section 6.11, " Radiation Protection Program" states, " Procedures for personnel radiation protection shall be prepared consistent with the requirements of 10 CFR Part 20 and shall be approved, maintained and adhered to for all operations involving personnel radiation exposure."
Procedure RCF3-310, " Personnel Dosimetry Quality Assurance" approved and maintained pursuant to Technical Specification 6.11 establishes in Section 5.0, "Self-Reading Dosimeter vs. Thermoluminescent Dosimeter Evaluations",
the criterion and action required in the event an individual's dose as measured by his self-reading dosimetea and TLD differ by more than + 25%
and the dose is greater than 150 mrem as determined by the TL.
.
On September 20, 1979, the licensee processed several TLD's worn by workers engaged in pipe hanger, or bolt inspection, and repair activities in both Unit 1 and Unit 2 Auxiliary Buildings.
These dosimetry results indicated differences of more than 25% from the individuals self-reading dosimeter results.
The licensee began an evaluation as required by Section 5.0 of RCP 3-310.
The licensee began by reading the TLDs of 54 other workers involved in performing the same work.
Of these 54, 24 had differences of more than 26% hetween the sum of their SRD readings and their TLD result.
Of the 24 with differences greater than 25%, 15 had differences of greater than 35%.
In 66% of the 24 cases, the error was positive, indicating the sum of the SRD readings was greater than the TLD reading.
In 33% of the cases, the error was negative, indicating the TLD reading was greater than the sum of the SRD readings.
The licensee had taken the following actions at the time of the inspection:
1.
Two individuals who's difference was negative and who's TLD results indicated exposure in excess of the licensee's administrative limits, were restricted from further radiation work until the investigation is complete.
The inspector noted that the total third quarter exposure for each of these individuals was 1480 mrem and 1860 mrem, respectively, as measured by TLD, and that each individual had a properly completed Form NRC-4 on file and that the limits of 10 CFR 20.101(b) had not been exceeded.
2.
A radiation protection technician was assigned responsibility to re1d and record each individual's SRD reading as they entered and returned from the controlled area.
3.
The Radiation Safety and Chemistry Foreman held a meeting with the contractor workers and discussed the dose discrepancies and radiation protection requirements in general.
4.
The individuals with the largest discrepancies were interviewed.
The inspector also interviewed the individual that had received the dose of 1480 mrem for the second quarter.
5.
The calibration of the TLD reader was verified.
Several of the TLD involved were calibration checke.
6.
Some of the SRDs used were source and drift checked.
7.
Detailed resurveys were performed in the vicinity of pipe hangers 417 and 419 on September 26, 1979.
The inspector noted that these surveys may not be representative of the dose rates present in the area on September 11, 1979 during reactor shutdown.
8.
Other survey data, logs and records are being collected for review.
Section 5.2.3 of RCP 3-310 states:
"A TLD vs. SRD Error Report, RCP-3-310-3, detailing differences greater than + 35% between SRD and TLD badge measurements for exposures greater than TSO mrem as determined by TLD shall be reported to Radiation Safety and Chemistry Engineer if the Radiation Safety and Chemistry Foreman cannot determine the cause of the discrepancies."
And Section 5.2.6.4. states:
"If the error is greater than 35% and the SRD(s) have satisfactory source and drift tests, perform evaluation in Section 6.2."
The licensee had not completed his evaluation at the time of this inspection.
The licensee has taken reasonable actions in the interim.
It is necessary for the licensee to complete several items such as source and drift tests of SRDs and readout of other TLDs prior to completion of his evaluation.
The NRC will review the licensee's evaluation of these September 1979 dosimeter discrepancies in a subsequent inspection (50-317/79-18-03, 50-318/79-15-03).
The inspector reviewed other records to determine the previous history of dosimetry discrepancies.
Generally, it appears that the sum of SRD readings for a given TLD period usually exceeds the TLD measured dose by about 20%.
According to licensee representatives, about 2% of all dosimetry measurements exceed the 25%
descrepancy criterion.
Review of data for February 1979 did not indicate any discrepancies in excess of 25%.
March 1979 data indicated 2 instances which required evaluation.
In both cases the SRD were found to be defectiv Rr"iew of the June 1979 TLD vs. SRO Error Report, form RCP-3-310-3 indicates toe following discrepancies in excess of 35%.
SRD Source Individual TLD SRD Discrepancy and Drift Check mrem mren
%
A 290 445
+ 53 Sat B
150 240
+ 60 Sat C
180 283
+ 57 Sat
170 2E3
+ 64 Sat E
320 SE0
+ 75 Sat F
230 495 vil5 Sat G
260 449
+ 72 Sat H
190 390
+105 Sat I
190 269
+ 94 Sat J
270 717
+165 Reject K
150 266
+ 77 Sat L
230 437
+ 90 Sat M
330 522
+ 58 Sat The inspector noted that the entire June 1979 dosimetry data package had been reviewed, signed off and filed by licensee representatives.
The J.une 1979 RCP-3-310-3 form had been signed off by the Rad-Chem Foreman but was not signed off by the Rad-Chem Engineer.
The Radiation Chemistry Technician, responsible for dosimetry, Radiation Chemistry Foreman, Plant Health Physicist, and Radiation Chemistry Engineer did not recall performing the evaluations required by Section 5.2.4 of RCP 3-310.
RCP 3-310 requires in Section 6.3 and 6.4 that:
"6.3 Whenever an abnormal dosimetry evaluation is performed, an Exposure Evaluation Report, RCP-3-310-4, shall be prepared by the RSCF and submitted to the RSCE for approval.
Copies of RCP-3-310-2, RCP-3-310-3 and RCP-3-302-1 shall be attached when appropriate.
6.4 RCP-3-310-4 shall be filed in the individuals's radiation exposure records".
The inspector reviewed individuals A, B, C, D, E, L and M's individual radiation exposure records.
There was no Exposure Evaluation Report RCP-3-310-4 filed for any of these individuals.
Failure to perform the evaluation of a TLD vs. SRD errors of greater than 35% as required by Section 5.2.6.4. of procedure RCP 3-310 represents noncompliance with lnit 1 and Unit 2 Technical Specifications 6.11 150-317/79-18-04, 50-318/79-15-04).
5.
Exit Interview The inspector met with licensee representatives including those denoted in paragraph 1 at the conclusion of the inspection on October 5, 1979.
The inspector summarized the purpose, scope and findings of this inspection.
The inspector expressed concern with the frequency of entries into the containment with the reactor at power.
The licensee representative stated that these entries are made in accordance with the "ALARA" criterion and that corrective maintenance will be performed during the October outage to correct the safety injection tank leak problem.
The licensee representative stated that they will, within 30 days, revise their procedures to insure appropriate review and evaluation is given to potential skin dose resulting from noble gas exposure.
The licensee representative stated that they will, within 90 days, revise their procedures to include a beta quality assurance program for their TLD system.