IR 05000312/1982017
| ML20053C681 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 05/18/1982 |
| From: | Book H, Hamada G, Temple G, Wenslawski F NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML20053C676 | List: |
| References | |
| 50-312-82-17, NUDOCS 8206020460 | |
| Download: ML20053C681 (9) | |
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U. S. NUCLEAR RECUL\\ TORY COMSSION
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REGION V
Report No. 50-312/82-17 Docket No. 50-312 treense 30, DPR-54 Saf2 guards croup Licensee: Sacramento Municipal Utility District 1708 59th Street, Box 15830 Sacramento, California 95813 Facility Name: Rancho Seco
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Inspection at: Clay Station, California Inspection conducted:
April 5-9, 1982 Mt d.
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Inspectors:
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G. H. Hamada, Radiation Laboratory 5pecialist Date Signed ( '~Tn %, n h D o.
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E-l 5 - 22 G. 'M.
Tentprle, Radihtlori lecunician (InstrumenLaLlon)
Date Signed Date Signed
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/f g2 Approved by:
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F. Wens awski, Chief, Reactor Radiation erotection Sec.
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Approved by:H. E. Bodk, Chiet, Haalological 5arety t5ranco Date Signed
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Summary:
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Inspection of April 5-9, 1982 (Report No. 50-312/82-17)
Areas Inspected: Routine announced inspection of laboratory quality control program including independent confirmatory measurements involving the Region V Mobile Laboratory. The inspection consisted of a total of 64 hours7.407407e-4 days <br />0.0178 hours <br />1.058201e-4 weeks <br />2.4352e-5 months <br /> onsite by one inspector and one radiation technician.
Results: No items of noncompliance were identified in the areas inspected.
RV Form 219 (2)
8206020460 020518 DR ADOCK 05000
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DETAILS 1.
Persons Contacted E. Bennett, Chemistry / Radiological Assistant
- R Miller, Chemistry / Radiological Supervisor
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- S. Nicolls, Senior Chemistry / Radiological Assistant
- Those present at exit interview.
2.
Discussion During the period of this inspection Rancho Seco was several days into a shutdown mode due to planned inspection and maintenance activities.
The independent measurement verification effort involving the Region V Mobile Laboratory consisted of split sample comparisons with the licensee. The results of these comparisons for the various sample categories selected are presented below.
Table 1 Reactor Coolant (Decay Heat Removal System)
I (10 ML Liquid Scintillation Vial Geometry)
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Rancho NRC Ratio Agreement Nuclide AW Ci/ml 4tCi/ml Rancho /NRC Range
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Mn-54 1.63 E-3 1.61 E-3 1.01 0.75 - 1.33 Co-58 9.32 E-2 9.36 E-2 1.00 0.85 - 1.18 Co-60 1.79 E-3 2.08 E-3 0.86 0.75 - 1.33 Tc-99m 5.92 E-4 4.20 E-4 1.41 0.60 - 1.66 I-131 8.89 E-3 8.87 E-3 1.00 0.80 - 1.25 I-132 3.06 E-3 2.55 E-3 1.20 0.75 - 1.33 Cs-134 7.49 E-3 6.82 E-3 1.10 0.80 - 1.25 Cs-136 9.31 E-4 9.75 E-4 0.96 0.50 - 2.00 Cs-137 7.82 E-3 7.80 E-3 1.00 0.80 - 1.25 i
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Table 2A
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Waste Gases
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-(Decay Tank "C")
.(1 Liter Marinelli Geometry)
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Rancho
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NRC
. Ratio Agreement Nuclide:
A Ci/ml jeCi/ml jaCi/ml Rancho /NRC Range
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' -Kr-85 1.59 E-3 ~
1.28 E-3 1.09 E-3 1.17 0.80 - 1.25
le-133
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5.91 E-3 5.76 E-3 1.03 0.85 - 1.18 Xe-133m-1.45 E-5 1.09 E-5 9.34 E-6 1.17 0.80 - 1.25 Xe-131m
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1.19 E-4
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- Calibration parameters obtained with liquid standard were corrected for a gas ~ matrix.
Table 28 Waste Gases (Decay Tank "C")
NRC Measurement of Rancho and NRC Samples (1 Liter Marinelli Geometry)
Rancho Sample NRC Sample Nuclide
/4 Ci/ml
/> Ci/ml Kr-85 1.05 E-3 1.09 E-3 Xe-131m 1.18 E-4 1.19 E-4 Xe-133 5.86 E-3 5.76 E-3 Xe-133m 1.05 E-5 9.34 E-6 Table 1 shows the relatively good agreement obtained for split samples of reactor coolant (decay heat system).
Table 2A lists the results obtained by the licensee and NRC for their respective 1 liter Marinelli beaker samples of fission gases. However, since the calibration parameters used by the licensee for this geometry were obtained with a liquid simulated standard, the licensee's results needed to be corrected for a gas matrix to make them comparable to the NRC data. This was done by estimating the "mean path length" (approximately 2.5 cm.) and applying the appropriate attenuation coefficients for the energies involved. When this is done, the results indicate adequate agreement. The above split samples in the 1 liter Marinel?5 beaker configuration were done for the purpose of ttis inspection ody.
The licensee normally uses a 4 liter Marinelli beaker for measuring waste gases prior to release. Because the sample was too active for a 4 liter configuration, a 1 liter size was used. Even with the smaller 1 liter sample, the licensee's gama spectrometry system became overloaded (in the Xe-133 channel), thus limiting the counting time to 110 seconds.
This in turn, decreased the measurement sensitivity for other fission gases present in lesser amount.
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-3-Table 28 is intended to show the internal consistency of similar measurements.
Here, NRC measured both the NRC and licensee samples, and as can be seen, the results agree very well. This indicates that the sampling procedure was adequate.
Table 3 Auxiliary Building Gas Sample (Point 4 - Minus 20 f t. Level)
(1 Liter Marinelli Geometry)
Rancho *
NRC Ratio Agreement Nuclide f Ci/cc p Ci/cc Ranchc/NRC Range Xe-133 3.61 E-4 3.91 E-4 0.92 0.85 - 1.18 Xe-133m 3.15 E-6 4.89 E-6 0.64 0.6 - 1.66 Xe-131m
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5.98 E-6
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Xe-135
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2.61 E-7
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Table 3 shows the results from a grab sample obtained at the minus 20 ft. level of the auxiliary building when an unscheduled release of radioactive gases occurred during this inspection.
Tables 4A, 48, 5A, 58, 6A and 68 show the results for particulate filter and iodine cartridge samples obtained by both the licensee and NRC. NRC's particulate filter coupled to a charcoal cartridge was placed side by side with the licensee's particulate filter coupled to its silver zeolite cartridge in the reactor building.
In both cases, constant flow pumps (2 CFM) were used to collect samples of approximately 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br /> duration.
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Rancho's Silver teolite Versus NRC's Charcoal Rancho NRC Silver Zeolite Charcoal Ratio Agreement Nuclide p Ci/cc j Ci/cc Rancho /NRC Range l
I-131 2.32 E-11 1.95 E-11 1.19 0.80 - 1.25
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1.20 E-12
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Cs-137 2.07 E-11
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Glass Fiber Glass Fiber Ratio Agreement Nuclide u Ci/cc u Ci/cc Rancho /NRC Range
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Cs-137 4.49 E-12
'8.04 E-12 0.56 0.75 - 1.33 Mn-54 1.98 E-13
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Cc-58
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1.44 E-12
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Co-60 6.48 E-13
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I-131 2.64 E-13
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Cs-134
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3.14 E-12
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Table SA
"NRC's Charcoal Cartridge
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(Measured by both Rancho and NRC)
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Rancho NRC
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Nuclide
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I-131 2.82 E-11 1.95 E-11 I-133
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1.20 E-12 Table 58 i
NRC's Particulate Filter Paper Sample
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i Rancho NRC Ratio Agreement Nuclide
,ju Ci/cc A4Ci/cc Rancho /NRC Range j
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1.98 E-13
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Co-58
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1.44 E-12
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1-131
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2.64 E-13
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Cs-134 2.60 E-12 3.14 E-12 0.83 0.75 - 1.33 Cs-137 8.52 E-12 8.04 E-12 1.06 0.80 - 1.25
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1.53 E-13
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'2.32 E-11 1.72 E-11
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1.25 E-12 I-133
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Cs-134
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4.43 E-12 Cs-137 2.07 E-11 1.16 E-11
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Table 6B j
Rancho's Particulate (Glass Fiber) Filter Paper Sample (Measured by both Rancho and NRC)
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Rancho NRC Ratio Agreement
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Nuclide
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Range
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Co-58
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2.8 E-14
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3.16E-13
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1.29E-12
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Cs-137 4.49 E-12 3.14E-12 1.43 0.75 - 1.33 l
Table 4A indicates agreement between the licensee and NRC for I-131 in the respective cartridge samples.
Because NRC's measurement system is more sensitive than the licensee's system, NRC results will normally show activities not detected by Rancho. Table 6A lists the activities detected by the NRC on Rancho's silver zeolite cartridge. This contrasts with NRC's charcoal cartridge where only iodine activities were detected.
Table 4B shows that Rancho's particulate filter was low by about a factor of 2 for the single result obtained by Rancho. These results'
indicate that activities normally associated with particulates (cesiums and cobalts) somehow got into the silver zeolite cartridge.
In addition, the Cs-137 activity found in Rancho's cartridge was considerably greater than that on the filter paper. These results suggest the possibility of a defective filter or filter mount.
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-6-Tables SA and 6A are included to show the relative results obtained by the licensee and the NRC for both the NRC's charcoal cartridge sample and the licensee's silver zeolite cartridge sample, respectively.
Since the licensee's calibration was done with a silver zeolite cartridge standard and the NRC's calibration with a charcoal cartridge standard, in general, it would not be expected that the results would agree very well. On the other hand, it is conceivable that reasonable agreement can be achieved under certain circumstances, e.g., when the activity is deposited on a thin surface layer and equivalent surface loaded standards are used. These results are included here only to show the relative agreement or disagreement that was obtained for this particular situation.
As a first approximation, filter paper standards of similar size with activity uniformly distributed over the active surface would be expected to exhibit similar calibration characteristics.
If this is the case, it would be valid to compare results from either or both filter paper samples.
Table 5B shows the results obtained by Rancho and NRC for NRC's filter paper scmple. As can be seen, the agreement is adeqcate.
On the other hand, Table 68 indicates that agreement was not achieved for the licensee's filter paper sample. This is very likely related to the problem mentioned earlier with respect to the licensee's filter paper sample.
For example, if the flow rate through the paper is highly irregular because of weak spots in the paper, such as the edges, the particulate deposition pattern would also be irregular. This could cause differences in measured results depending on the measurement geometry used.
In the above tables it is seen that in most cases NRC detected radionuclides not detected by the licensee's system. This is because of the more sensitive NRC measurement system and the longer counting times used by the NRC. Rancho's measurements, while less sensitive, are adequate to meet the detection limit criteria specified by the licensee's technical specifications.
Review of other licensee counting systems indicated that the measurement procedures for these systems also conformed with their respective detection limit specifications.
Even if counting procedures per se are adequate, the results may not be valid if other related criteria are inadequate. Specifically, the sampling and analysis procedures for SR-89, SR-90 in liquids and filters, and H-3 in air were found to be weak in certain respects. When analyzing for SR-89, SR-90, a radiochemical yield of 5 percent or less is occasionally obtained. Regardless of the yield, the sample is processed for counting and reported as a valid result. The inspector pointed out that a provision should be included in the procedure to require reanalysis of the sample whenever radiochemical yield fractions fall below about 30-40 percent, and also that yield factors be included in determining the counting times needed to satisfy the detection limit specifications. For the tritium in air measurement requirement, Rancho uses a water bubbler system, where air is bubbled through a water trap to capture tritiated
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-7-water vapor. The nominal water volume in the trap is 100 ml and depending on temperature and humidity conditions and volume of air processed, the ending volume of the water trap could be as low as 80 ml. The ending volume is adjusted back to 100 ml with clean water after which a sample is obtained for tritium assay. An efficiency factor of 90 percent is used for the exchange in the bubbler. When the inspector questioned the validity of the dilution step in this procedure, licensee personnel agreed that this appeared to be inappropriate and that corrective action would be taken for this as well as for the SR-89, SR-90 analysis procedure. The licensee indicated that henceforth, a silica gel system
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will be used to collect ~and measure tritium in air.
While the, licensee's gamma spectroscopy system appears to be adequate under most circumstances, there are certain weaknesses in the system
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that need.to be strengthened. This is apparently a one-of-a-kind system
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both~from the standpoints of hardware and software. No one on the current" staff fully understands or is capable of manipulating the software
,to its full potential. For example, because the system does not appear to respond to commands for changing half lives in the nuclide library, the half 1ife of MN-54 remains as 302 days although it was pointed out du' ring:last year's inspection that the generally accepted half life for MN-54 is 312 days.. Also, as mentioned earlier, the licensee's system had difficulty cou.nting the waste gas comparison sample (1 liter Marinelli)
because the count capacity per channel was quickly overloaded. The licensee, in fact, had been working to correct this situation and as of this inspection date, an order had been placed to purchtse a state-of-the art computer-based multi-channel analyzer system to replace-the current-system. This system is expected to be operational by sometime in August. At that time, a complete set of calibration parameters will be generated with new standards. When this has been done, NRC will send the licensee a test solution for analysis. This solution will contain mixed gammas, SR-89, SR-90, tritium, and an alpha emitter for gross alpha analysis.
(Item No. 82-17-01)
In addition to providing a test for the new gama spectroscopy. system, the test solution is intended to provide a basis for assessing the validity of the licensee's analysis capability of beta emitting radionuclides.
During this inspection, two separate liquid waste tank samples were split with Rancho. The intent was to send RESL (Radiological and Environmental Sciences Laboratory of the Department of Energy), NRC's contractor laboratory, a portion of the split to be analyzed for SR-89, SR-90, H-3, gross alpha, and gross beta. When the licensee's measurements indicated no significant gama or beta activity for either sample, it was decided that the test sample method would be a more meaningful comparison.
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Exit Interview.
Inspection findings were discussed with 1.icensee personnel indicated
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in paragraph.l'
Weaknesses in the SR-89, SR-90 and tritium in air
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procedures were pointed out. The licensee agreed that corrective action was indicated and that steps would be taken immediately to
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implement an appropriate action for each situation.
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