ML12066A171

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DOE/ID-10739 (2011), Annual Radiological Environmental Monitoring Program Report for the Three Mile Island, Unit 2 Independent Spent Fuel Storage Installation
ML12066A171
Person / Time
Site: Three Mile Island, 07200020  Constellation icon.png
Issue date: 02/29/2012
From: Hall G
Idaho National Lab
To:
Office of Nuclear Material Safety and Safeguards, US Dept of Energy (DOE)
References
EM-FMDP-12-017 DOE/ID-10739 (2011)
Download: ML12066A171 (10)
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DOEIID-10739 (2011)

Annual Radiological Environmental Monitoring Program Report for the Three Mile Island, Unit 2 Independent Spent Fuel Storage Installation G. G. Hall, CHP Published February 2012 Idaho National Laboratory Idaho Nuclear Technology and Engineering Center Idaho Falls, Idaho 83415 Prepared for the U. S. Department of Energy Assistant Secretary for Environmental Management Under DOE Idaho Operations Office Contract DE-AC07-051D14516

ABSTRACT This report presents the results of the 2011 Radiological Environmental Monitoring Program conducted in accordance with 10 CFR 72.44 for the Three Mile Island, Unit 2, Independent Spent Fuel Storage Installation. A description of the facility and the monitoring program is provided. The results of monitoring the two predominant radiation exposure pathways, potential airborne radioactivity releases and direct radiation exposure, indicate the facility operation has not contributed to any increase in the estimated maximum potential dose commitment to the general public.

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SUMMARY

The purpose of this report is to present the results of the Radiological Environmental Monitoring Program (REMP) conducted during 2011 for the Three Mile Island, Unit 2, (TMI-2), Independent Spent Fuel Storage Installation (ISFSI). TMI-2 core debris was transferred to the ISFSI between March 1999 and April 2001 and remains in interim storage at the ISFSL.

The REMP was implemented from January through December 2011. Results of the loose surface radioactive contamination surveys indicated no increase in either beta or Cs-137 radioactivity attributed to the facility operation. The results of the airborne radioactivity sampling did indicate the presence of Cs-137, but it was not indicative of releases of airborne particulate radioactivity from the loaded Horizontal Storage Modules (HSM) that would contribute to an increase in the estimated maximum potential dose commitment to the general public. The presence of Cs-137 detected during airborne radioactivity sampling is attributed to the March 2011 nuclear reactor accident in Fukushimna, Japan. The results of the thermoluminescent dosimetry network did not indicate an increase in radiation levels above pre-operational background attributed to tile facility operation.

The monitoring program results support the conclusion reached in the Final Environmental Impact Statement that operation of the facility will not result in a significant dose commitment to the Maximum Exposed Individual.

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CONTENTS ABSTRACT ................................................................................................................................. 2 SUM MARY ................................................................................................................................. 3 INTRODUCTION ............................................................................................................. 5 PROGRAM DESCRIPTION ....................................................................................................... 5 RESULTS ..................................................................................................................................... 6 DISCUSSION .............................................................................................................................. 8 CONCLUSION ............................................................................................................................ 9 REFERENCES .......................................................................................................................... 10 FIGURES

1. TM I-2 ISFSI TLD Station Locations ........................................................................... 6 TABLES I. Highest Radiation Level Summary Inside HSM Rear Panel Doors (mrem/h) .............. 7
2. TM I-2 ISFSI Air Sample Results (pCi/m 3 ) .................................................................. 7
3. TMI-2 ISFS[ TLD Results (mrem/d) ....................................... ...... 8
4. TMI-2 ISFSI Estimated Airborne Radioactive Material Releases (Ci/y) .................... 9 4

Annual Radiological Environmental Monitoring Program Report for the Three Mile Island, Unit 2, Independent Spent Fuel Storage Installation INTRODUCTION The Three Mile Island, Unit 2, Independent Spent Fuel Storage Installation (TMI-2 ISFSI) is a spent fuel dry storage facility designed for interim storage of the TMI-2 core debris. The TMI-2 ISFSI, located within the Idaho Nuclear Technology and Engineering Center (INTEC) at the Idaho National Laboratory (INL), is operated by CH2M - WO Idaho, LLC for the Department of Energy (DOE). The TMI-2 ISFSI was licensed on March 19, 1999 by the Nuclear Regulatory Commission (NRC) pursuant to 10 CFR 72 for authorization to receive, possess, store, and 2 transfer spent fuel and fuel debris, resulting from the 1979 TMI-2 accident, for a twenty-year term."1 The TMI-2 ISFSI is a modified NUHOMS spent fuiel storage system, designated NUHOMS-12T.

Each of the thirty NUHOMS-12T modules within the facility provide for the horizontal dry storage of up to twelve TMI-2 stainless steel canisters inside a dry shielded canister (DSC) which is placed inside a concrete horizontal storage module (HSM). The NUHOMS-12T modification includes venting of the DSC through high efficiency particulate air (i-IEPA) grade filters during storage. The vent system allows for release of hydrogen gas, generated due to radiolysis, and monitoring and/or purging of the system during operation.

The TMI-2 core debris which had been stored in stainless steel canisters in a fuel pool at the Test Area North (TAN) site within the INL has been transferred to the TMI-2 ISFSI for interim storage. A Settlement Agreement entered into by the State of Idaho, the Department of Energy, and the Department of the Navy in October 1995 established a schedule for commencing core debris transfers by March 31, 1999, and completing such transfers by June I, 2001.3 The first core debris transfer was completed on March 31, 1999. Nine additional transfers were completed during 2000. The remaining nineteen transfers were completed during 2001, with the last one completed on April 20, 2001.

A Radiological Environmental Monitoring Program (REMP) was developed for the TMI-2 ISFSI and implemented in accordance with 10 CFR 72.44. This report presents the REMP results during the TMI-2 ISFSI operation in 2011.

PROGRAM DESCRIPTION The REMP is designed to monitor the two predominant radiation exposure pathways inherent with the facility design: potential airborne radioactivity releases and direct radiation. The airborne radioactivity release pathway is monitored using a combination of loose surface radioactive contamination surveys and periodic airborne radioactivity sampling. The direct radiation exposure pathway is monitored using thermoluminescent dosimetry (TLD) located along the outer perimeter fence of the TMI-2 ISFSI. Contact radiation levels on the HSM rear panel doors and DSC purge and vent port filter housings are also measured during regularly scheduled surveillances performed in accordance with the Technical Specifications.

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Loose surface radioactive contamination surveys are performed at the vent and purge ports of each DSC as well as the drain port of each loaded HSM. The survey frequency was monthly during the First year, quarterly during the second through fifth years, and is now annually. The frequency coincides with the radiation monitoring surveillance schedule required by the TMI-2 [SFSI Technical Specifications. Sample media is analyzed for beta radioactivity. Depending on the amount of beta radioactivity detected, gamma isotopic analysis is either performed for each sample or for an annual sample composite. The presence of Cs-137 is qualitatively determined (or quantitatively as necessary) during the gamma isotopic analysis.

Twenty-two TLD stations are located and maintained along the outer perimeter fence of the TMI-2 ISFSI. The TLD station locations are noted in Figure 1. Dosimetry is changed out on a quarterly frequency. The minimum detectable dose is no greater than 10 orero.

Figure 1. TMI-2 ISFSI TLD Station Locations.

40 41 42 43 44 45 46 47 28127126125124123 221211201191181171511 II I I I I I I I I I I I lII

/ 60 0 TLD Location N Air Sampler 49'

.59 15114113 12 111 10 1 7 6 5 4 3 I9 50-0 1:58 57 56 5j 54 53 52 51 A low-volume air sampler is used to collect air through a particulate filter during a seven-day period each month. The air sampler is located between the two rows of HSMs inside the TMI-2 ISFSI.

Each air particulate sample is analyzed for beta radioactivity with an LLD no greater than 0.01 pCi/m3 .

Depending on the amount of beta radioactivity detected, gamma isotopic analysis is either performed for each air particulate sample or for an annual sample composite. The presence of Cs-137 is qualitatively determined (or quantitatively as necessary) during the gamma isotopic analysis.

RESULTS The radiation levels measured on the HSM rear panel doors during 2011 were all less than I mrem/h; well below the Technical Specification limit of 100 mrem/h. The radiation levels measured on the DSC purge and vent port filter housings during 2011 were all less than or equal to 13 mrem/h; well below the Technical Specification limit of 1,200 mrem/h. Radiation levels for HSMs 4 and 22 include 3 mrem/h neutron radiation attributed to either spontaneous fission of Pu-240 or AmBeCm neutron startup source material. The highest gamma radiation levels measured in the purge and vent port filter housing access areas during 2011 are summarized in Table 1.

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Table 1. Highest Radiation LevelSummary Inside HSM Rear Panel Doors (mrem/h)'.

HSM/DSC Dose Rate HSMl/DSC Dose Rate HSM/DSC Dose Rate 1/29 25 11/12 22 21/9 20 2/28 20 12/19 35 22/5 100 3/26 13 13/15 20 23/16 10 4/I 15 14/17 36 24/1I 20 5/24 6 15 Empty 25/13 32 6/23 26 16/2 <1 26/ 23 7/22 13 17/3 35 27/8 10 8/21 20 18/20 38 28/10 4 9/25 30 19/18 50 29/27 10 10/6 24 20/4 80 30/14 70 The loose surface contamination survey results for the purge, vent, and drain ports were less than the Mininun Detectable Activity (MDA), 23 dpm/ 100 cm2 beta/gamma and 18 dpm/1 00 cm 2 alpha, calculated in accordance with NUREG/CR-1507.5 The gamma isotopic results for the purge, vent, and drain port contamination survey composite samples from the HSMs indicated no fission product radioactivity. Cs-137 radioactivity was less than M.DA which averaged 2E-2 nCi/sample; well below the required LLD of 5 nCi/sample.

Monfltly air sampling beta radioactivity results for the TMI-2 ISFSI are presented in Table 2.

Beta radioactivity was not detected above tle established threshold of 4E-14 .Ci/cc (0.04 pCi/m 3) on each of the monthly samples collected from January through November. Beta radioactivity for the sample collected in December was detected above the established threshold. Gamma spectroscopy results of the composited air samples collected from January through November did indicate tile presence of Cs-137 at a radioactivity concentration of 7E-4 pCi/mr3 when averaged over the eleven week air volume collected. Gamma spectroscopy results of the air sample collected in December did not indicate the presence of fission or activation product activity. Naturally occurring K-40 and Pb-212 were detected in both the composited sample (January through November) and the December sample.

Table 2. TMI-2 ISFSI Air Sample Results (pCi/n 3 ).

Sample Date Beta Sample Date Beta January 0.02 July 0.02 February 0.01 August 0.02 March 0.04 September 0.02 April 0.01 October 0.02 May 0.01 November 0.02 Jtine 0.01 December 0.08 TLD results are presented in Table 3 in units of mrem/d. TLD results include an artificial phantom backscatter correction of 3% to express the results in dose equivalent units. Quarterly standard deviations were generally less than or equal to 0.1 mrem/d. Analysis of variance results indicated quarterly variances were in all cases different than the pre-operational baseline variance measured in "Gamma and neutron 7

March 1999. T-test results indicated quarterly mean TLD responses were in all cases significantly lower than the pre-operational baseline mean measured in March 1999 due to introduction of a new environmental dosimeter and processing system in June 1999.6 Mean TLD responses ranged from 0.5 to 0.8 mrem/d. Radiation monitoring at other locations within the 100 meter perimeter was not performed due to extremely low building occupancy factors.

Table 3. TMI-2 ISFSI TLD Results (mrem/d).

LOCATION MAR JUN SEP DEC MEAN 40 0.6 0.6 0.6 0.7 0.6 41 0.5 0.6 0.6 0.6 0.6 42 0.5 0.6 0.5 0.6 0.5 43 0.5 0.6 0.5 0.6 0.5 44 0.5 0.6 0.5 0.6 0.5 45 0.5 0.5 0.5 0.6 0.5 46 0.5 0.5 0.5 0.5 0.5 47 0.5 0.5 0.5 0.5 0.5 48 0.5 0.5 0.5 0.5 0.5 49 0.5 0.6 0.5 0.6 0.6 50 0.5 0.6 0.6 0.6 0.6 51 0.6 0.7 0.7 0.7 0.7 52 0.6 0.7 0.7 0.7 0.7 53 0.7 0.8 0.7 0.8 0.7 54 0.7 0.8 0.7 0.8 0.7 55 0.7 0.8 0.8 0.8 0.8 56 0.7 0.8 0.8 0.9 0.8 57 0.8 0.9 0.8 0.9 0.8 58 0.8 0.9 0.8 0.9 0.8 59 0.7 0.9 0.8 0.9 0.8 60 0.6 0.7 0.7 0.7 037 61 0.6 0.7 0.7 0.8 0.7 MEAN 0.6 0.7 0.6 0.7 0.6 DISCUSSION The TMI-2 ISFSI REMP was conducted in accordance with established procedures. There were no changes made to the TMI-2 ISFSI REMP during 2011.

The loose surface radioactive contamination survey and vent port radiation survey results (stable trends) neither indicate a build up of radioactivity in the vent port HEPA filters, nor a breach of DSC containment. Gamma spectroscopic results of composited loose surface contamination survey media indicated no fission or activation product activity.

The detection of Cs-137 during the airborne radioactivity sampling program is attributed to the nuclear reactor accident in Fukushima, Japan and subsequent resuspension of fallout radioactivity during range fires and dust storms at the INL. The Fukushima event occurred on March 1I, 2011. Subsequent to tlhe event the State of Idaho, Department of Environmental Quality (DEQ), INL Oversight Program began detecting fission product radioactivity (1-131, Cs-i 34, and Cs-137) in environmental samples (air and/or precipitation) collected from their on-site, boundary, and distant sampling station locations. The detection continued through April 2011. The presence of 1-131 was indicative of a recent fission event.

The average airborne Cs-137 radioactivity concentration detected by DEQ was 6.5E-4 + 4.1E-4 pCi/m 3; similar to that reported above for the TMI-2 ISFSI REMP. 7 An average airborne Cs-137 radioactivity 8

concentration of 3E-2 pCi/rn 3 was also reported by the Environmental Protection Agency based on air samples collected from their RadNet monitoring station in Boise, Idaho from March 21 through 23, 2011 .'

The louse surface radioactive contamination surveying and airborne radioactivity sampling results indicate there has been no measurable release of radioactive material from the DSCs stored in the HISMs at file ISFSI above and beyond that projected in the Final Environmental Impact Statement (EIS),

estimated for 40 CFR 61 reporting'purposes, and summarized in Table 4.9, 0." Radioanalytical results are not significantly different fromn pre-operational results as well as those projected in the EIS and reported in accordance with 40 CFR 61.

The radiation dosimetry results indicate there has been no measurable increase in ambient background radiation levels outside the TMI-2 ISFSI perimeter fence attributed to storage of the TMI-2 core debris. The absence of any significant increase in radiation levels outside the TMI-2 ISFSI perimeter fence also supports conclusions reached in the EIS.

Table 4. TMI-2 ISFSI Estimated Airborne Radioactive Material Releases (Ci/y).

Radionuclide Release Radionuclide Release Rudionuclide Release Cs-137 1.5E-2 Co-60 7.I E-5 1--3 2.OE+2 Sr-90 1.2E-2 Pu-239 3.2E-4 Eu- 155 1.5E-5 Pu-241 6.1 E-3 Srn-151 2.4E-4 Pu-238 7.4E-5 Kr-85 1.4E+3 Pu-240 1.61-4 Sb-125 2.IE-6 Pm- 147 2.3E-5 Ni-63 1.4E4 Cs- 134 2.8E-7 Am-241 4.1 E-5t Eu-154 4.4E-5 1-129 3.OE-2 Calibration and quality control of instrumentation used for beta analysis of surface contamination and airborne radioactivity sample media is maintained in accordance with procedures used by the Idaho Cleanup Project (]CP) Radiological Control Program.12 Radioactivity sources used for instrumentation calibration and quality control are traceable to the National Institute of Standards and Technology (NIST).

CONCLUSION Airborne radioactivity releases and direct radiation exposure from the facility during 2011 did not contribute to any increase in the estimate of maximum potential dose commitment to the general public; characterized as 2.7E-3 mrem/y to the Maximum Exposed Individual reported in tie EIS. There were no radioactive liquid effluents released *from the facility, hence no radionuclides to report.

t This release value from tie TMI-2 ISFS[ SAR Table 7.2-3 accounts for Am-241 in-growth.

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REFERENCES I Materials License SNM-2508 for the Three Mile Island, Unit 2, Independent Spent Fuel Storage Installation (TAC No's L22283 and.L22800), March 19, 1999, Docket No. 72-20.

2. 10 CFR 72, "Licensing Requirements for the Independent Storage of Spent Nuclear Fuel and High-Level Radioactive Waste," Code of FederalRegulations, Office of the Federal Register, October 2004.
3. Settlement Agreement between the State of Idaho, Department of the Navy, and the Department of Energy, October 16, 1995.
4. Technical Specifications and Bases for the INL TMI-2 Independent Spent Fuel Storage Installation.
5. NUREG/CR-1 507, "Minimum Detectable Concentrations with Typical Radiation Survey Instruments for Various Contaminants and Field Conditions," December 1997.
6. P. E. Ruhter, New Em'iroiunentalDosimeterResponse, letter PER-] 7-99, July 29, 1999.
7. State of Idaho, Department of Environmental Quality, INL Oversight Program, Etnviroomental Sunveillance Programn QuarterlyDataReports, January - March 2011 and April - June 2011.
8. Environmental Protection Agency, Envirofacts, EPA Region 10, 2011
9. NUREG-1626, "Final Environmental Impact Statement for the Construction and Operation of an Independent Spent Fuel Storage Installation to Store the Three Mile Island Unit 2 Spent Fuel at the Idaho National Engineering and Environmental Laboratory," Docket No. 72-20, March 1998.
10. 40 CFR 61, "National Emission Standards for Hazardous Air Pollutants," Subpart H, "National Emission Standards for Emissions of Radionuclides Other Than Radon from Department of Energy Facilities," Code ofFederalRegulations, Office of the Federal Register, October 2002.
11. G. G. Hall, ProjectedRadiontclideEmnissionsfo'om the TA'f-2 ISFSI, Engineering Design File 3420, February 25, 2003.
12. ICP, RadiologicalControl ikfanzials 15B and 15C.

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