ML20057D232

Responds to NRC Re Violations Noted During Insp of Facility.Corrective Actions:Purchased New Model MGS0500 Mixed Gamma Std to Use for Germanium Detector Calibr,Per HP-105.Contests Part of Violation Re Fnr HP Procedures

ML20057D232
Person / Time
Site:	University of Michigan
Issue date:	09/30/1993
From:	Fleming R MICHIGAN, UNIV. OF, ANN ARBOR, MI
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9310040008
Download: ML20057D232 (10)

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MICHIGAN MEMORIAL-PHOENIX PROJECT 35m 3034 PHOLNIX MEMORIAL LABORATORY ANN ARBO't. MICHIGAN 4810%2100 '

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- September 30,1993 l

t U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Docket 50-2 License R-28 l

Re: REPLY TO A NOTICE OF VIOLATION dated 1 September 1993.

l Gentlemen:

The Notice of Violation refers to two distinct instances in which FNR Ilealth Physics procedures were not followed:

1) IIP-105 "FNR Pool Water Analysis" requires that a germanium detector l

calibration be carried out with "One 500 mi plastic bottle filled with a mixed radionuclide water standard traceable to NBS" (3.3.2.1) and (5.2.1.1).

In i

January 1992, we began using Standard Radionuclide Source No. 41857-250, "500 mL Solid in 500mL Wide Mouth HDPE Nalgene Bottle" provided by Analyics,Inc; a copy of the certificate is attached. This is an eight-nuclide source.with a water-equivalent matrix, whose calibration was confirmed by NIST as per the certificate. This standard source clearly satisfied the l

requirements of IIP-105. The source itself, but. not the certificate, gives an l

" expiration date" of January 1993. The NRC inspection contends that this j

" expiration date" somehow effected the adequacy of this standard after January 1993. We considered this issue in January 1993 and again this month, and we conclude that the source fully satisfied the the requirements of IIP-105.

l Therefore we contest this part of the Violation.

1

2) IIP-210 " Ar-41 Capintec Ionization Chamber Calibration Procedure" requires that the nroduction of the in-house, cobalt-60 syringe standard used for Ar-41 calibration be carried out "with a certified NBS standard" (9.2) using a germanium spectrometry system. Whereas the calibration of the Capintec detector for Ar-41 must be done semi-annually, the production of the Co-60

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syringe standard using an NBS certified standard is only done as needed. The syringe standard in use during the inspection was most recently calibrated to

-l have an activity of 0.293 uCi on March 31, 1982,' and this calibration was done on a GELI detector calibrated with an NBS standard, as required by HP Procedure 210. This work was documented in a MEMO TO: the Capintec Ionization Chamber Calibration Logbook from Mark Driscoll (Health Physicist) ent'illed " Routine Calibration of the Capintec Ionization Chamber (HP Procedure 210)", dated. April 1,1982. The inspection report (p.8) states,

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I U.S. Nuclear Regulatory Commission September 30,1993 page 2 l

" Procedure IIP-210,.., required that the Capintec detector be calibrated against j

an NBS traceable standard prior to its use in the GAD calibration". This is just -

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not true, llP-210 requires that the Capintec detector be calibrated with a j

syringe containing Ar-41 (steps 10.7-10.10), which has been quantified using the in-house, syringe Co-60 standard (steps 9.5-9.9 and steps 10.1-10.6). The only mention of the use of a certified NBS standard in 11P-210 is in step 9.2, which was done in the original calibration of the Co-60 syringe standard. This point is emphasized in the Background Information. Section 4. of 11P-210, which states" An important concept to remember in performing this cross-l calibration of instruments is that the argon-41 sample counted by the GELI i

spectrometer, and later used to calibrate the Capintec, must be in the same l

geometry as the cobalt-60 standard used to determine the counting efficiency l

of the GELI spectrometer." The argon-41 sample is required to be in a 5 cc l

plastic syringe (step 10.4), and therefore so is the Co-60 standard used (steps 9.6 j

and 9.7). Therefore. we contest this part of the Violation. as well.

t Reasons for the Violations l

The reason for the violation is that the NRC inspectors questioned the adequacy of two of our radionuclide standards for the purpose of carrying out Procedures IIP-105 and IIP-210. In both cases we have concluded that the standards i

used were both appropriate and adequate to carry out these procedures, that they were used as specified in the procedures, and therefore that we did not violate our procedures. llaving said that, two points should be made. As a result of this exercise, I

we have made signifcant improvements to our procedures and to our calibration measurements, as described in the next section. Second, gamma spectrometrists can

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debate forever, and probably will, what is the best way to calibrate a gamma spectrometer - mixed sources or single nuclide, six lines or eight, as well as the i

fitting algorithm. And, while we are always looking to improve our techniques and j

procedures as the state-of-the-art in gamma spectrometry evolves, our current calibration methods are completely adequate for the health physics applications at hand.

1) 11P-105 Calibration Standard The contention of the inspection report is that the Analytics Standard 41857-250 was not an NHS traceable calibration standard after the " expiration date" of January 1993. In discussions with Dr. Daniel Montgomery of Analytics, Inc. we were told that not only was NHS traceability in no way effected by the "e xpiration date", but that the " expiration date" had NO scientific or measurement significance. This date, which appears on the source but not on its certificate, was put on at the request of company auditors and some users. It also has obvious marketing value. It is certainly true that the source was one year older in January 1993 than on its calibration date of January 1,1992 and that some of the calibration lines were weaker. A user should evaluate its adequacy for his or her purpose, as we did at the time.

Last year, the facility health physicist made a conscious decision to use the Analytics source for 1

another year to save the unnecessary cost of replacement. At that time he discussed with the gamma spectrometrists in our lat' oratory, and in fact with 1

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U.S. Nuclear Regulatory Commission September 30,1993 page 3 l

t its director, the adequacy of this source for our pool water measurements. We 3

concluded that the " expiration date" was arbitrary, that the short-lived lines were not needed, and that there were advantages of continuity in not -

j switching sources. Indeed, the health physicist had stopped using the 279 kev l

line from 46 day Ilg-203 before the January 1993 " expiration date". It is worth noting that neither our new mixed radionuclide standard, which we purchased i

after the inspection, nor any NIST produced radionuclide standards have

" expiration dates". Also last year, as well as each time it is used, the physical integrity of the source was confirmed. We believed then, and we do now, that l

the Analytics standard was completely adequate for use with IIP-105. Ilowever, as a result of the NRC inspection, we have purchased a new mixed radionuclide standard.

2) llP-210 Calibration Standard j

The calibration standard used in IIP-210 is exactly the one repired by the procedure, was produced by calibration against an NBS certified standard as j

described in the procedure, and therefore its use did not violate our procedure.

However, as a result of the NRC inspection, we have purchased a new l

commercial gas-equivalent syringe standard of Co-60 whose calibration is traceable to NIST.

In neither case do we believe that the use of the sources in question violated our procedures IIP-105 and 11P-210.

Corrective Steps Taken to Avoid Further Violations i

1) IIP-105 Mixed Radionuclide Standard i

i) On September 9,1993 we purchased a new Model MGS0500 Mixed Gamma i

Standard, Serial Number A1491, from North American Scientific, Inc. to use with for germanium detector calibration as per llP-105. ( A copy of the f

2 Certificate is attached.) A comparison of the detector calibration done with

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this new source to that done with the Analytics standard showed that the i

efficiencies were almost identical for energies above 500 kev and within a few percent at lower energies. This confirms the adequacy of the Analytics standard for use with HP-105.

ii) No significant changes are required to the HP-105 procedure. We will change 3.3.2.1 to read "One 500 mL plastic bottle filled with a mixed radionuclide water, or water-equivalent, standard traceable to NIST." This will reflect'the current good practice of using 500 mL calibration standards deposited on a water-equivalent solid matrix, rather than in solution.

We believe that eit h er of these two 500 mL mixed radionuclide standards are adequate to satisfy HP-105. Indeed, the calibration results are essentially equivalent.

It is very unlikely that interchanging these standards would ever effect a health physics decision concerning pool water analysis. Our ability to properly carry out

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11P-105 has not been significantly effected by this change. However, we continue to

U.S. Nuclear Regulatory Commission September 30,1993:

page 4 use the new North American Scientific standard to avoid future violations. In addition, we have a much heighten sensitivity on maintaining the integrity of our radionuclide calibration standards.

2) IIP-210 Co-60 Syringo Standard i) On September 9,1993, we purchased a custom Co-60 syringe standard from North American Scientific, Inc. to use for calibrating our germanium detector for Ar-41 measurement. On September 9,1993, a calibration of an Ar-41 source was carried out with both syringes giving results within 3 percent of each other. A direct comparison of the new syringe standard with our in-house Co-60 syringe standard showed that the activities agreed to 8 percent, well within the uncertainties of the two standards. This confirms the adequacy of the FNR syringe standard that we had been using for the past eleven years with 11P-210. We have specified this new standard to have about 5 uCi of activity as compared to 0.06 uCi activity of the o:d standard. This will improve the precision of measurement of the approximately 7 uCi syringe of Ar-41 used to calibrate the GAD's.

ii) We are making major changes to the way that the GAD calibration has been done as a direct result of the issues raised in this inspection. The-misunderstanding on the part of the inspectors as to how and when the NBS certified standard was required in llP-210 is an example of complicated flow of this evolution. Procedures IIP-210 and llP-209, GAD Calibration Procedure, will-be combined such that the measurement of the Ar-41 activity injected into the GAD drum will be carried out entirely using a calibrated germanium detector.

The use of the Capintec detector is no doubt a vestige of the days when the short halflife of Ar-41 (1.82 hours9.490741e-4 days <br />0.0228 hours <br />1.35582e-4 weeks <br />3.1201e-5 months <br />) and the long data-reduction time of gamma spectrometers required the use of an intermediate detector with a transfer calibration. Today, this is no longer so, and the use of the Capintec detector only degrades the accuracy of the final GAD calibration. Therefore, we will include the calibration of the germanium detector with the new Co-60 syringe standard and the measurement of the the Ar-41 syringe activity on the germanium detector in IIP-209, and eliminate procedure IIP-210 altogether.

This will both significantly simplify the GAD calibration and improve the accuracy of the final result.

We believe that the replacement of the Co-60 syringe standard and the elimination y the Capintec detector from the GAD calibration procedure will significantly simplify and improve this evolution. Ilowever, the two syringe standards give essentially the same results in terms of accuracy, confirming the validity of our previous calibra-tions. Our use of the in-house Co-60 syringe standard did not violate Procedure 210:

Procedure 210 requires it use.

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U'.S. Nuclear Regulatory Commission September 30,1993 page 5 -

Date When Full compliance Will be Achieved We believe that we have always been in compliance in regards to these violations.

Ilowever, whether the NRC upholds the violations or not, as of September 9,1993, when the new calibration standards were received and when the accuracyof our previous calibrations was confirmed, we are in full compliance.

All necessary procedure modifications will be carried out before they are used.

Sincerely, e

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Ronald F. Fleming Director ec:

J. Martin Regional Administrator Region 111 U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137-5927

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liso scaixard industnalibulnard ANALYTICS wo. cm,rm ;..m m n:w-l CERTIFICME OF CALIBRATION l

Standard Radionuclide Source 41857-250 500 mL Solid in 500 mL Wide Mouth HDPE Nalgene Bottle This standard radionuclide source was prepared using an aliquot of C.01665 grams measured gravimetrically from a master radionuclide solution source which was calibrated using a germanium gamma spec-trometer system.

This calibration has been confirmed by the National Institute of Standards and Technology through participa-tion in a Measurements Assurance Program as described in USNRC Regulatory Guide 4.15, Revision 1,

February 1979.

Confirmation was obtained for each gamma-ray listed below to within the stated limits.

The gamma-ray emission rate for this source is given below.

For convenience when using multiple standards prepared from the same master source, the gamma-ray emission rate per gram of the T. aster i

radionuclide solution source is also given.

US Paten 4,430,258; UK Patent GB2,2A9,194B; CA Patent 1,196,776.

Density of solid matrix 1.15 g/cc.

Calibration date: Janupey 1, 199h 12:00 EST

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Source prepared by: (C, [f N. Q)o E.

Sel vin', Production Manager ZASTER THIS TCTAL GAMMA SOURCE SOURCE UNCERTAINTY ISOTOPE ENERGY HALF-LIFE GPS FER GM GPS i

Cd-109 is 462.6 d

.J}500 1823 4.5 Co-57

_22 171.7 d

~2080 1217

.5 ce-139

_56 137.64 a

112200 1868

,.6 Ha-203

9 46.60 d

165400 2804

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.5I200 2634 4.2 Cs-137

62 30.0

..:?200 2318

.5 c-88 299 106.01 3

4 3500 6885 4.5 Co-60

.;~3 5.2714 7

"24100 3398 5.0 Co-60

.232 5.2714

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224300 3901

,.4 Y-68 536 106.51 d

425300 7248 2.5

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' CERTIFICATE OF CALIBRATIONSWP C E ',,-

MODEL MGS0500MDtEDGAMMA STAleARD '

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SERIAL NUMBER A1491

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Reference Date Aur==* 1.1993 at 1200 PDT TOTAL.

- ;. Na S-RADIONUCLlDE ACTMTY UNCERTAINTY (HALF-LIFE 1' LEVEL

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~ EMISSIONS kev'

(% INTEMarTY)'

Am-241 193.9 nCi 3.50 %

59.5364 (E7)

(432.7 years)

Cd-10E 1.620 pCl 3.91 %

an rn43 g33)..,

(1.2665 years)

Co57 51.33 nCl 3.94 %

122.0612 95.5)'

l (271.77 days) 136.473tf (10.89) e i

Te-123m 61.35 nCi 3.93%

158.989 94.0)

(119.7 days)

Cr 51 1.795 pCi 3.87%

320.084 (923)

(27.704 days) l I

Sn-113 314.7 nCi 3.87%

391.690 (64) i (115.09 days) l Sr-85 320.1 nCI 3.85%

513.296 (99.27) j (64.84 days) j 1

Cs.137 238.6 nCi 3.91%

661.600 (8521)

I (30.0 years)

Y-88 554 8 nCi 3.85%

898.065 (92.7) 1 (106.61 days) 1836.077(99.35)

- Co.60 237.7 nCi 3.94 %

1173237 f99.90)

(5271 years) 1332.501 199.9824) i i

SOURCE DESCRIPTION The activity is uniformry mired in 500 cc of a 1.07 g/cc matrix and transferred to a customer supphed bottle.

METHOD OF CALIBRATION I

Mixed nuctide solutions are prepared by dispensing gravimetric abouets of individual, or mixtures of. cahbrated nuchde solutions into a master batch. Aliquots of the master batch were then gravimetricaHy transfe red to the water equivalent matrix.

The nuchde solutions were calibrated using a nigh purity Germanium cetector energy vs. ettciency curve estabhshso and verified througn ongoing interoompansons with the National institute of Standards and Technology. This standard is indirecify Omplictity) traceable to l-the National Institute of Standaras and Tecnnology.

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North American Scientite, Inc. actively parteipates in the Radcactivity Measurements Assurance Program cx) rums::ted by the National f

institute of Standards and T,nology in

. ration with the U.S. Council for Energy Awareness.

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7**74-93 Cahbration Laboratory Date PErEDENCES i

(1)

Table of Aaa+oactive tsotooes. 7th ed: tion.1986 1

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. LEAK TEST CERTIFICATION ON REVERSE.

l North Amenc3n Scentfic,Inc.

7435 Greenbusn Ave., North HORywood CA 91605 (818)503-9201

3x (818) 503-0764 i

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LEAK TEST METHOOS -

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1.

Soek p 1 M.) Test - (ISO /TR 48261979 (E) secten 2.13)

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The souirce is immersed in water or other suitable liquid at SOT for at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and the acevity '

in the liquid measured. Acceptance limit CD001 pCi alpha,0.001 pCl beta-gamma.

2.

Immersion Test (ANSI N542-1977, Appencix A2.13)

The source is immersed in water at 100% for 10 minutes. The water is removed and the source coated.

'I and rinsed using frenh water. These operations are repeated twice, boiling in the water from the previousrinsingoperahon. Acceptancelimit:OD001 Cialpha,0.005pCibeta$ammaforalltheweser i

collected.

3.

Wipe (Smear) Test (ANSI N5421977, Appendix A2.1.1)

All external surfaces of the source are wiped with a piece of filter paper or other absorbent material which has been moistened with an appropriate solvent and the actrvity removed is measured.

l Acceptance limit: 0.0001 pCi alpha,0.001 Cl beta-gamma.

4.

Leak Test Not Applicable l

For sources with no covering or a delicate covenng over the radioactive portion or gas standards I

and sources, the inactive portions or containment vessel are wipe tested as in Method 3 above Acceptance limit: 0.0001 Ci alpha,0.001 pCl beta-gamma.

5.

Other l

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LEAK TEST CERTIFICATION The standard was leak tested in accordance with Leak Test Method 3 as described above.

The removable activity was determined to be less than 0.001 pCi beta-gamma and -less than 0.0001 pCi alpha.

This leak test should be performed every six nonths or as required by a specific NRC or Agreement State License.

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- CEKlu1CATE OF CALIBRATION CUSTOM GAMMA STANIMRD Radionuclide.

Co-60 Activity 4.980 uCi Serial Number A1493 Reference Date Aucust 1. 199'L Half-Life'2' 5.271 0.001 vears PRINCIPAL EMISSIONS'*'

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p TvDe EnerT/ (kev)

Intensity (%)

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c gamma 1332.501 99.9824 i

gamma 1173.237 99.90 SOURCE DESCRIPTION A gravimetric aliquot of a calibrated Co-60 solution is evenly distributed in approximately 3 cc a 0.015 g/cc matrix and transferred j

to a customer supplied syringe.

METTIOD OF CALIBRATION l

The Co-60 solution was calibrated on a high purity Germanium detector using Co-60 efficiency at 1173.237 kev.

This efficiency was established with a standard traceable to the National Institute of Standards and Technoloay.

This standard is indirectly (implicitly) traceable to the National Institute of Standards and Technology.

North American Scientific, Inc. participates in the Radioactivity Measurements Assurance Program conducted by the National Institute of Standards and Technology in cooperation with the U.S. Council for Energy Awareness.

TOTAL UNCERTAINTY (99% Confidence Level)

Systematic uncertainty

_ r z.26%

Weighing uncertainty r 0.79%

Total uncertainty

3.05%

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Calibration Laboratory Date REFERENCES j

'1)

Table of Radicacti/e Isotones, 7th edition l'986.

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LEAK TEST CERTIFICATION ON REVERSE.

Nonn Amencan Sc:entihc. Inc.

335 Greenousn Ave. Nonn Hollywood. CA 91505 f 818)503 9201

m818)503G64 f

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1.

Soak (Immersion) Test (ISO /TR 4826-1979 (E) section 2.1.3)

The source is immersed in water or other suitable liquid at 50*C for at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and the activity in the liquid measured. Acceptance limit: 0.0001 Ci alpha,0.001 pCi beta-gamma.

2.

Immersion Test (ANSI N542-1977, Appendix A2.1.3)

The source is immersed in water at 100*C for 10 minutes. The water is removed and the source cooled and rinsed using fresh water. These operations are repeated twice, boiling in the water from the previous nnsing operation. Acceptance limit: 0.0001 Ci alpha,0.005 Cl betagamma ftv all the water collected.

3.

Wipe (Smear) Test ( ANSI N542-1977. Appenoix A2.1.1)

All extemal surfaces of the source are wiped with a piece of filter paper or other absorbent matenal which has been moistened with an appropriate solvent and the activity removed is measurea.

Acceptance limit: 0.0001 Ci alpha. 0.001 pCi betagamma.

4.

Leak Test Not Applicable For sources with no covenng or a delicate covering over the radioactive portion or gas standaros and sources. the inactive portions or containment vessel are wipe tested as in Method 3 above.

Acceptance limit: 0.0001 Ci alpha. 0.001 gCi beta-gamma.

1 5.

Other LEAK TEST CERTIFICATION The standard was leak tested in accordance with Leak Test Method 3 as described acove.

The removable activity was determined to be less than 0.001 uCi beta gamma.

This leak should be performed every six months or as required by

• est a specific NRC or Agreement State License.

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