IR 05000312/1981011
| ML20037D041 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/14/1981 |
| From: | Book H, Hamada G, Wenslawski F NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML20037D040 | List: |
| References | |
| 50-312-81-11, NUDOCS 8105210263 | |
| Download: ML20037D041 (10) | |
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U. S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT
REGION V
Report No.
50-312/81-11 Docket No.
50-312 License No.
DPR-54 Safeguards Group Licensee:
Sacramento Municipal Utility District 1708 59th Street, Box 15830 Sacramento, California 95813
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Facility Name:
Rancho Seco Inspection at:
Clay Station, California Inspection conducted:
March 16-20, 19E'
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G. H. Hamada, Kaolation LaDoratory bpeclailSt
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Approved by:
t. We slawski, Unier, Keactor naolation rroteccion Da'te Signed
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Approved By:
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H. E. Book, Chief, Radiological Safety Branch
' Date Signed Summary:
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Inspection of March 16-20, 1981 Report No. 50-312/81-11 Areas Inspected:
Routine announced inspection of laboratory ouality control program including independent confirmatory measurements usi.ng the Region V Mobile Laboratory. The inspection involved a total of 70 hours8.101852e-4 days <br />0.0194 hours <br />1.157407e-4 weeks <br />2.6635e-5 months <br /> onsite by one inspector and one radiation laboratory technician.
Results: No items of noncompliance or deviations were identified in the areas inspected.
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l EV Form 219 (2)
8105210 2[r8 Q
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DETAILS 1.
Persons Contacted R. Bowser, Chemical and Radiation Assistant
- R. Colombo, Technical Assistant l
- D. Gardiner, Senior Chemical and Radiation Assistant
- F. Kellie, Assistant Chemical and Radiation Supervisor
- R. Miller, Chemical and Radiation, Supervisor
- J. Newey, Senior Chemical and Radiation Assistant S. Nicolls, Chemical and Radiation Assistant
- P. Oubre', Plant Superintendent D. Price, Chemical and Radiation Assistant
- Indicates those present at the exit interview.
2.
Measurements and Intercomparison of Data Intercomparison Measurements for gamma ray emitting radionuclides were made with the Region V Mobile Laboratory measurement system.
This system consists of a ND-6600 computer based multichannel analyzer array (with associated Nuclear Data (ND) sof tware) coupled to an intrinsic germanium detector setup.
This inspection was conducted at a time when Rancho Seco was on a refueling and maintenance outage.
(Since late January,1981).
The following intercomparison measurements were performed.
a.
Liquid Sample Since the operational objective at Rancho Seco is to keep liquid effluents to minimal or zero levels, samples of low level liquid effluents are not routinely available. Therefore, a sample of loop "B" decay heat coolant was obtained for comparative analysis.
The results are summarized in Table 1.
An aliquot of this ; ample was obtained for shipment to the Radiological and Entironmental Sciences Laboratory (RESL) of the Department of Energy for tritium, gross beta, and SR-89, SR-90 analyses.
Results of these comparisons will be reported in a subsequent inspection report (81-11-01).
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TABLE I LIQUID SAMPLE - DECAY HEAT COOLANT "B"-
SMUD/NRC NUCLIDE SMUD (uCi/ml)
NRC (uCi/ml)
Ratio-4
-5 Co-57 1.06 X 10 8.54 X 10 1.24 Cr-51 2.29 X 10-3 2.12 X 10-3 1.08-3
-3 Cs-134 4.90 X 10 4.45 X 10 1.10-3
-3 Cs-137 6.03 X 10 5.66 X 10 1.06-2
-2 Co-58 5.38 X 10 5.09 X 10 1.06-3
-3 Ag-110M 2.88 X 10 2.71 X 10 1.06-4
-4 Fe-59 1.73 X 10 1.37 X 10 1.26-3 Co-60 1.91 X 10-3 2.21 X 10 0.86 The comparisons were made on the basis of criteria developed in
" Criteria for Comparing Analytical Measurements" (see attachment).
The resolution range of 8-15 (see attachment) was chosen because Region V experience to date with the mobile measurement system indicates an uncertainty of approximately 10 percent...While the
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random counting error is relatively small (or can be made.small),
other errors, particularly those associated with. systematic effects, can be much more significant. Until Region.V is able to more precisely quantify all of the error components, the 10 percent error estimate and thus also the 8-15 resolution range will be used.
It can be seen that all of the nuclides in Table 1. fall into the agreement category; i.e., the licensee value divided by the NRC value falls within the range 0.6-1.66.
b.
Gas Sample
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Gas samples were obtained from Waste Gas Decay Tank "c".
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samples were obtained while a release was in progress. Two glass bulb sample container s measuring 26.1 cc (NRC) and. 31.8.cc (SMUD).
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were connected in series to obtain the samples. The bulbs were flushed for about 5 minutes before collecting the samples. The l
j results are tabulated in Table 2.
TABLE 2 GAS SAMPLE - WASTE GAS DECAY TANK "c" 31.8 cc Bulb (SMUD)
l NUCLIDE SMUD (uCi/cc)
NRC (uCi/cc)
Ratio-3
-3 Xe-133 3.04 X 10 2.81 X 10 1.08-3
-3 Kr-85 7.83 X 10 7.13 X 10 1.10-3
-4 Xe-131M 1.04 X 10 9.16 X 10 1.14 l
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- 26.1 cc Bulb (NRC)
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SMUD/NRC NUCLIDE SMUD(uCi/cc)
NRC (uCi/cc)
Ratio-4
-4 Xe-133 8.32 X 10 9.19 X 10 0.90 Kr-85 2.22 X 10 1.90 X 10-3 1.17-3 Xe-131M 2.98 X 10 2.40 X 10-4 1.24
~4 All nuclides in Table 2 fall into the agreement category; i.e., -
the licensee value divided by the NRC value falls within the range 0.6-1.66.
- Due to a faulty stop cock, some of the gas leaked from this bulb.
However, after resetting the stop cock, intercomparison measurements were performed, since it was still valid for this purpose.
c.
Particulate Filter Samples A particulate filter sample from the auxiliary building stack was obtained for measurement by both SMUD and NRC..The results are shown in Table 3.
' TABLE 3 PARTICULATE FILTER - AUXILIARY BUILDING STACK NUCLIDE SMUD (uCi/cc)
NRC-(uCi/cc)
I4 Co-58 DL*
9.4 X 10 I4 Co-60 DL*
4.2 X 10-
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- DL = Detection limit The quantity of radioactive material in this sample was low l
enough to cause SMUD to report only less-than-detection-limit I
levels for all nuclides. The reason for the low but positive results for Co-58 and Co-60 measured by NRC was due mainly to
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the longer counting time used by NRC.
It is noted that the
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I licensee's detection limit did meet technical specification l
requirements.
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Another particulate filter sample (grab sample) representing a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> collection from the 60 feet level of the reactor
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building was also obtained for comparative measurements.
The results are tabulated in Table 4.
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TABLE 4 PARTICULATE FILTER - REACTOR BUILDING - 60 FEET LEVEL SMUD/NRC NUCLIDE SMUD (uCi/cc)
NRC (uCi/cc)
Ratio-12-12 Cs-134 4.87 X 10 2.79 X 10 1.74-12-12 Cs-137 8.17 X 10 6.21 X 10 1.32-II-12 Co-58 1.31 X 10 9.61 X 10 1.36-12-12 Co-60 3.56 X 10 2.05 X 10 1.73-I3 Cr-51 DL*
6.69 X 10
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-13 Mu-54 DL*
6.14 X 10
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Zr-95 DL*
5.17 X 10-13
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-13 Nb-95 DL*
7.82 X 10
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- DL = Detection limit The radioactivity level in this sample was again quite low as in the previous case. The licensee reported four positive results versus eight for the NRC.
It might be noted, however, that the corresponding NRC values for th'e four nuclides for which SMUD reported less-than-detection-limit levels only indicate a level about an order of magnitude lower than the. positive values reported. The licensee measurements. meet technical specifications for detection limits.
Among the four positive results reported, two (Cs-137 and Co-58) fell in the Agreement category and the other two (Cs-134 and Co-60) fell in.the Possible Agreement category.
The licensee's values for the two nuclides in.the Possible l
l Agreement category indicated relatively high counting error L
uncertaintics, measuring 30 percent for Cs-134 and 40
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percent for Co-60.
Because the level of activity in the two particulate filter samples measured was so small, the test for agreement between SMUD and NRC was less than definitive. As a' further test for this type of sample, SMUD was asked to measure NRC's particulate filter standard. The results are summarized.in. Table 5.
l TABLE 5 PARTICULATE FILTER - NRC STANDARD SMUD/RESL UCLIDE SMUD ( s/ min.)
- RESL ( s/ min)
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3 Co-57 6.80 X 10 4.43 X 10 1.53 Cs-137 2.94 X 10 2.50 X 10 1.18
4 Co-60 4.93 X 10 3.94 X 10 1.25
4 Y-88 7.28 X 10 6.62 X 10 1.10
- The reference time for RESL's values.is March 19,19.;J at 0700.
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It can be seen that although the ratios all fall in the
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Agreement category, the licensee's values appear to be biased slightly high in the conservative direction. A partial explanation could be due to the fact that the licensee's and NRC's calibration geometries for particulate filters, while similar, are not identical.
d.
Charcoal Cartridae A charcoal cartridge sample.(grab sample) was.obtained from the 60 feet level of the reactor building for gamma analysis.
This sample corresponded to the particulate filter sample from the same location (see Table 4) and represented a.24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> collection. The intercomparison meascrement results are given in Table 6.
' TABLE 6 CHARC0AL CARTRIDGE ~- REACTOR BUILDING
'60 FEET LEVEL SMUD/NRC NUCLIDE SMUD (uCi/cc)
NRC (uCi/cc)
Ratio-12-12 I-131 5.67 X 10 7.81 X 10 0.73 The only significant activity detected.<as I-131, and as can be seen, l
the results agree within the prescribed range for, agreement.
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might be noted that altho. ugh the cartridge was measured twice with opposite faces down against the detector, only one side showed
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positive I-131 activity, indicating a face-loaded distribution of I-131 in the cartridge.
It appears that the face-loaded geometry was the key factor in the relative agreement between SMUD and
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NRC, since NRC's calibration for th'e charcoal cartridge geometry l
was performed with a cartridge of significantly different physical dimensions than SMUD's cartridge (5.6 cm. diameter by.2.5 cm high for NRC versus 4.7 cm diameter by 5.6 cm high for SMUD). Also,
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since NRC's calibration was based on a homogeneously loaded cartridge, NRC's measurement of a face-loaded geometry would be l
biased high as is the case.
As an additional check, the licensee was asked to measure and l
quantify NRC's (RESL) charcoal cartridge standard (. homogeneous).
l The results are given in Table 7.
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TABLE 7 CHARC0AL CARTRIDGE - NRC STANDARD - HOMEGENE005 SMUD/NRC NUCLIDE SMUD ( s/ min.)
- RESL ( s/ min)
Ratio 5.27 X 10f 4.43X10f 1.19 Co-57 Cs-137 2.31 X 10 2.50 X 10 0.92
5 Co-60 3.86 X 10r 3.94 X 10 0.98
Sr-85 1.61 X 10j 1.72 X 10 0.94
Y-88 6.60 X 10 6.21 X 10 1.06
4 Sm-133 8.24 X 10 8.51 X 10
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- Reference time is March 19, 1980 at 0700.
The results all fall in the Agreement Category. For this measurement, the licensee used calibration factors.obtained with a cartridge standard similar in dimension to the NRC cartridge.
No items of noncompliance or deviations were. identified.
3.
Additional Measurements During the course of this inspection, a reportable event. involving a containment building radioactivity alarm occurred at Rancho Seco.
One of the procedures in the subsequent investigation.of this event by SMUD personnel included obtaining samples of reactor building air through a sampling line normally used for this purpose. Since this presented an opportunity to obtain an air sample in the Marinelli beaker configuration, NRC's one liter plastic Marinelli: beaker was connected in series with SMUD's 4.35 liter alumirum Marinelli beaker to collect the samples. No fission gas activity greater than the detection limit was found in either sample.
This finding thus tended to confirm the licensee's conclusion that the tripping of the alarm in the containment building monitor resulted not from. excessive activity in the reactor building air but from some;other cause. NRC examination of this event is discussed in IE Inspection Report 50-312/81-12.
No items of noncompliance or deviations were identified.
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4.
Review of Laboratory Quality Control Procedures and Practices Procedures involving quality control in sampling and measurement were reviewed.
In particular, two documents, " Chemistry and Radiochemistry Manual - AP-306" and " Counting Room Manual-AP-308" were reviewed.
These procedures are relatively detailed and include considerations for performing daily calibration check: and periodic background checks.
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Calibration checks are plotted on a control chart with the count -
rates of the Co-57 (122 Kev), Cs-137 (662 Key) and Co-60 (1332 Kev)
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energies as the controlling parameters.
Recounts are required if the count rates fall outside the two standard deviation (sigma) limits.-
The supervisor is notified if a point falls:outside the three sigma limits and corrective actions are taken as required.when this.happens.
Experience has shown that recounting after. careful repositioning of the-standard on the detector.almost always takes care of the problem.
It was pointed out to the~ licensee that it would be desirable also to include an energy vertus channel number control as a means of detennining whether or not an e.ergy recalibration was needed..The licensee agreed to implement this additional. control..
The licensee performs periodic oackground checks on the Ge-Li. detector
system as a means of assessing the contribution 'to. background from ambient air and the environs. Backgrounds are also taken with sample shelves in place to determine if any contaminating activity is
present and if so, its contribution to-the sample count.-
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The licensee performs its own tritium, Sr-89, Sr-90 and gross beta
assays. The calibration standard used for gross-beta is Co-60 (average beta energy-96 Kev). Since RESL'uses Cs-137 (average beta-i energy - 187 Kev) for calibrating gross beta. assays, differences in
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the results of the intercomparision samples.can be expected.
Nevertheless, since gross ' beta analysis.is basically a screeni.ng measurement, and liberal agreement criteria are usually. applied, agreement can still be achieved. Although there is no specific -
requirement for using a specified standard for calibrating gross.
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beta measurements, it would be desirable toistandardite intercomparison measurement's on a conur. radioactivity standard.
f During the period of this inspection, Rancho Seco was in the final l
steps of a recalibration effort for measuring fission gases...While-earlier calibrations involved using liquid standards for the various
i geometries used in gas measurements, this aost recent recalibration used a gas standard obtained from "Analytics" with a certification.that the l
standard was traceable to the National Bureau of Standards'(NBS).
The licensee's intercomparison result for the gas sample was based on this most recent calibration, and on the basis of the relative agreement j
between SMUD and NRC results, the calibration parameters for gases
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appear to be valid.
No items of noncompliance or deviations were identified.
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5.
Exit Interview At the conclusion of the inspection, inspector's findings were discussed with SMUD personnel referenced in Paragraph 1.
The licensee was informed of the agreement between SMUD and NRC on measurements performed on
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various intercomparison samples.
Licensee management was also apprised of the effort made by the NRC to obtain and measure reactor building air during the reportable event that occurred earlier in the week, and of the negative results obtained by NRC confirming the licensee's findings.
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ATTACHMENT CRITERIA FOR COMPARING ANALYTICAL MEASUREMENTS
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(LICENSEE VALUE)
RATIO (NRC REFERENCE VALUE)
Possible Possible Reso<ution 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
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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 ar? lied to the following analyses:
Gamma Spectrometry where principal gamma ene.rgy used for. identification is greater than 250 Kev.
Tritium analyses of liquid 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.
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90 Sr and Sr determinations.
Gross Beta where samples are counted on the same date using the same reference nuclide.
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-2-Procedure a.
The NRC Referenceitaboratory value should be divided by its associated uncertainty (lo) to obtain the resolution.
I b.
The ratio of the two measurements to be compared should be determined by dividing the result to be compared by the AEC Reference Laboratory results.
c.
Agreement is considered obtained if the ratio falls within therangegiveninthe" Agreement"columnfortheaggociated resolution.
For example, consider a comparison of Sr-5 determinations. A licensee obtains a value of 1.97. +.08 x 10 uCi/ml and the NgC Reference Laboratory reports a reifult of 2.53 +.06 X 10- uCi/ml. The resolution would be 42(2.53/.06)
and the ratio is 0.78(1.97/2.53). 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 ratio falls outside the appropriate "possible agreement" column, the two measurements will be considered to be in
" disagreement."
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