IR 05000133/1981004
| ML20039B140 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 11/24/1981 |
| From: | Book H, Hamada G, Hankins G, Wenslawski F NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML20039B134 | List: |
| References | |
| 50-133-81-04, 50-133-81-4, NUDOCS 8112220330 | |
| Download: ML20039B140 (8) | |
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U.S. NUCLEAR REGULATORY COMMISION OFFICE OF INSPECTION AND ENFORCEMENT Report tio. 50-133/81-04 Docket No. 50-133 License No.
DPR-7 Licensee: Pacific Gas and Electric Company P. O. Box 7442 San Francisco, California 94120 Facility flame:
Humboldt Bay, Unit 3 Inspection at:
Eureka, California Inspection Conducted:
October 19-22, 1981 N %O d/u^A U
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Inspectors:
G. H. Hamada, Radiation Laboratory Specialist Date Signed
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G. N. Hankins,' Radiation Instrumentation Technician Date Signed N 23
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Approved.by: F. Wenslawski, Chief, Reactor Radiation Protection Datt Sigfied Section
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Approved by:
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H. E. Bo6k, Chief, Radiological Safety Branch Date Signed Suninary:
Inspection of October 19-22, 1981 (Report No. 50-133/81-04)
Areas Inspected: Routine announced inspection involving capability test measurements and review of associated laboratory ouality control programs.
Intercomparison test measurements were performed using the Region V fiobile Laboratory. The inspection involved a total of 38 hours4.398148e-4 days <br />0.0106 hours <br />6.283069e-5 weeks <br />1.4459e-5 months <br /> onsite by one inspector and one radiation instrumentation technician.
Results:
No items of noncompliance were identified in the areas inspected.
8112220330 811124 PDR ADOCK 05000133 G
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DETAILS 1.
Persons Contacted B. Getty, Sr. Power Production Engineer
- R. Lund, RPM Foreman
- R. T. Nelson, Power Plant Engineer
- R. Parker, Sr. Chemical and Radiation Protection Engineer
- D. Peterson, QC Supervisor R. Stenner, Chemical and Radiation Protection Engineer
- E. Weeks, Plant Superintendent
- Indicates those present at exit interview.
2.
Measurements and Intercomparison of Data Intercomparison measurements were conducted on a number of different sample categories for which licensee measurements are still routinely perfornk.d. The criteria for deciding whether or not agreement has been achieved are given in attachent 1.
Results of intercomparison measurements are tabulated below.
SPENT FUEL P00L CRUD NRC NRC Humboldt Shelf-0 Ratio Shelf-2 Ratio Agrecaent Nuclide uCi/mi uCi/ml Humboldt/NRC uCi/ml humboldt/NRC Range-5
Cs-134 1.750X10- 1.356X10 1.29 1.63X10 1.07 0.6-1.66 Cs-137 2.138X10-
-4 Cs-60 1.421X10- 1.507X10-4 1.42 1.693X10 1.26 0.6-1.66-5
-5 1.178X10 1.21 1.587X10 0.90 0.6-1.66 The results above show agreement-for this sample category. A resolution of 10 (see attachment 1) was applied to this category because the calibration standard used for the calibration of the NRC measurement system was somewhat different from that used by the licensee.
Filterable material (crud) from the spent fuel pool was filtered onto a membrane filter paper approximately 2 inches in diameter. This was placed in a 2 inch Petri dish for counting. The counts for this geometry were quantified using efficiency factors obtained with NRC's particulate filter standard. Humboldt's calibration was performed with a standard identical in geometry to that of the sampl.
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-2-SPENT FUEL POOL WATER NRC NRC Humboldt Shelf-0 Ratio Shelf-2 Ratio Agreement Nuclide uCi/ml uCi/ml Humboldt/NRC uCi/ml Humboldt/NRC Range-4
-4-4 Cs-134 7.270X10 5.619X10 1.29 6.271X10 1.16 0.6-1.66-3
-3-3 Cs-137 9.126X10 6.600X10 1.38 6.487X10 1.41 0.6-1.66-5
-5-5 Co-60 5.600X10 6.003X10 0.93 8.803X10 0.64 0.6-1.66 A resolution of 10 was used for this category because we believe this to be the most appropriate value for this geometry at this time. This value will be modified if and when new calibration data so indicate.
Based on the resolution indicated, the overall agreement is adequate.
REACTOR WATER CRUD Humboldt NRC Ratio Agreement Nuclide uCi/ml uCi/ml Humboldt/NRC Range-7
-7 Cs-137 7. 716X10 7.409X10 1.04 0.5-2.0-7
-7 Mn-54 9.00X10 5.081X10 1.77 0.4-2.5-5
-5 Co-60 2.475X10 2.025X10 1.22 0.75-1.33 The agreement for this category is adequate as indicated above. The counting statistics for Mn-54 was poor for both licensee and NRC measurements.
REACTOR WATER Humboldt NRC Ratio Agreement Nuclide uCi/ml uCi/ml Humboldt/NRC Range-5
-5 Cs-137 1.50X10 1.30X10 1.15 0.6-1.66-5
-5 Co-60 1.44X10 1.97X10 0.73 0.6-1.66 Despite relatively poor counting statistics, the results show adequate agreement for the above sample.
WASTE HOLD TANK Humboldt NRC Ratio Agreement Nuclide uCi/ml uCi/ml Humboldt/NRC Range-7
-7 Mn-54 4.46X10 4.44X10 1.00 0.5-2.0-5
-5 Co-60 3.98X10 2.89X10 1.38 0.75-1.33-5
Cs-134 1.22X10 1.45X10 4 0.84 0.75-1.33-4 Cs-137 2.94X10 2.98X10-0.99 0.75-1.33
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-3-Although Co-60 in the above table falls in the "possible agreement" category, the overall agreement is generally adequate.
It might be noted that the licensee's value for Co-60 is in the conservative direction. NRC's measurement geometry for this sample.was a one liter Marinelli beaker configuration. The licensee's configuration was a four liter Marinelli.
STACK PARTICULATE FILTER Humboldt NRC Ratio AgrFement Nuclide uCi/ml uCi/ml Humboldt/NRC Range-I4-I4 Co-60 7.1X10 6.9X10 1.03 0.6-1.66 The only measurable activity detected in the stack particulate filter sample was Co-60. As can be seen in the above table, the agreement was quite good.
' STACK HALOGEN CARTRIDGE Humboldt NRC Ratio Agreement Nuclide uCi/ml uCi/ml Humboldt/NRC Range-I4-I4 Cs-137 2.90X10 2.28X10 1.28 0.6-1.66-15-I4'
Co-60 4.23X10 1.11X10 O.38 0.3-3.0 The count rate was minimal for this sample.
Humboldt's measurement gave only 12 net counts under the cobalt peak. The 2 sigma error for Co-60 was 83 percent, indicating that it was barely detectable.
Furthermore, a halogen cartridge is intended to measure radioiodine when present, and not Co-60 or Cs-137. Activities.ike Cs-137 and Co-60 are measured and quantified by counting particulate filter samples.
NRC POINT SOURCE (Amersham)
Humboldt Amersham Ratio Nuclide*
uCi uCi Humboldt/ Amersham-I
-I Cd-109 3.921X10 3.858X10 1.02-2
-2 Co-57 1.647X10 1.532X10 1.08 Ce-139 1.647X10 1.907X10-2 0.98-2
-2-2 Hg-203 5.481X10 5.163X10 1.06-2
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Sn-133 7.577X10 7.150X10 1.06-2
-2 Sr-85 9.361X10 8.908X10 1.05-2
-2 Cs-137 7.199X10 6.354X10 1.13 Co-60 7.519X10-2 7.551X10-2 1.00-I
-I Y-88 1.567X10 1.482X10 1.06
- All nuclides decay corrected to June 1,1981.
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A point source geometry is almost neser encountered in effluent measurement programs.
It is, however,'a useful.' measure of comparability if the facility is calibrated for this geometry.
It is relatively unambiguous in that one point: source is virtually indentical in geometry to other point sources. With appropriate standards, the agreement should be quite good. This is generally the case as can be seen in the above table. The value for Cs-137 seems slightly elevated as compared to the other nuclides.
If we examine the Cs-137 values for all of the other sample categories, it appears that Cs-137 is high for these other cases as well. The licensee indicated that a possible explanation for this might be in their method for obtaining the efficiency ' curve for the various geometries. Their technique for obtaining an efficiency curve is to perform a least squares exponential fit which gives equal weight to all points on the curve. For some of the older standards, the most reliable point is the Cs-137 energy (because of its long half life), yet the least squares technique gives it no more weight than any other point. If, because of the mix of energies used in the calibration and/or the peculiarities of the curve fitting routine, or other factors not immediately apparent, the efficiency curve undershoots the Cs-137 energy region (and this seems to be the case), Cs-137 results would tend to be high. The NRC curve fitting routine uses a " spline" fit.
A " spline" fit is a force fit of a cubic-through all of the points (energies) in a standard.
The slight upward trend for Cs-137 is not a significant problem at this point in Humboldt's operation.
If and when-Humboldt, Unit 3 begins to produce power again, a.more stringent measurement requalification -test would be performed prior to startup.
3.
Review of Quality. Assurance Procedures
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Procedures H-1 through H-7 under " Chemistry and Radiation Procedures" in the Plant Manual, Volume 8, were reviewed. These were found to be generally adequate. Other procedures are being developed. These are procedures that establish quality control " flag" points beyond which corrective actions are required. Currently, there is a computer program that provides separate weekly plots of ' efficiency (Co-60), resolution
'(Co-60),' centroid channel (Co-60), and energy versus channel. These constitute control parameters for corrective action as needed. These-programs are routinely performed on a weekly basis, but have not yet been written into procedures for the manual. This is being done.
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Exit Interview Inspection findings were-discussed with PG&E personnel referenced in Paragraph 1.
PG&E management was informed of the adequate agreement obtained for all samples analyzed by both PG&E and NRC. We encouraged the development and completion of written DC procedures for radioactivity measurement programs. Management was informed that if and when plans for the reactivation of Unit 3 are developed, another independent measurement verification effort will be conducted which would include additional laboratory. qualification test...-
ATTACHMENT CRITERIA FOR COMPARING ANALYTICAL MEASUREMENTS (LICENSEE VALUE)
RATIO (NRC REFERENCE VALUE)
Possible Possible Resolution Agreement Agreement A Agreement B
0.4 - 2.5 0.3 - 3.0 No Comparison 4-7 0.5 - 2.0 0.4 - 2.5 0.3 - 3.0 8 - 15 0.6 - 1.66 0.5 - 2.0 0.4 - 2.5 16 - 50 0.75 - 1.33 0.6 - 1.66 0.5 - 2.0 51 - 200 0.80 - 1.25 0.75 - 1.33 0.6 - 1.66 200 0.85 - 1.18 0.80 - 1.25 0.75 - 1.33
"A" criteria are applied to the following analyses:
Gamma Spectrometry w'are principal gamma energy used for identification is greater than 250 Kev.
Tritium analyses of liouid samples.
Iodine on adsorbers.
"B" criteria are applied to the following analyses:
Gamma spectrometery where principal gamma energy used for identification is less than 250 Kev.
90 Sr and Sr detenninations.
Gross Beta where samples are counted on the same date.using the same-reference nuclid. -.
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-2-Procedure
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The NRC Reference Laboratory value should be divided by its associated uncertainty to obtain the resolution.
b.
The ratio'of the two measurements to be compared should be determined
by dividing the result to be compared by the NRC Reference Labcratory results.
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Agreement.is considered obtained if the ratio falls within the range given in the " Agreement" column for the associated resolution. For obtains a value of 1.97 +.08-x 10- 90 determinations. A licensee example,considera~comparisonofSguCi/mlandtheNRCReference-5 Laboratory reports a result of 2.53 + ~.06 X 10 uCi/ml. The resolution
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would be 42 (2.53/.06) and the ratio is 0.78 (.l.97/2.53). This pair of measurements would be considered to be in " agreement" because for this resolution, the " agreement". range is 0.75 --1.33.
d.
If " agreement" is not achieved, the ratio should be evaluated for
"possible agreement".
In this. case, consideration is made for the type of analyses conducted by. selecting a range in the appropriate column;. i.e., A" analyses or_ "B" analyses.
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If the rheio falls outside the appropriate "possible agreement" column,
the two measurements will be considered to be_in " disagreement".
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