05000016/LER-1998-001, Submits Voluntary LER 98-001 Containing Info of Interest to NRC Which Did Not Specifically Meet Reporting Criteria of Section I.8 of Fermi 1 Ts.Notification Was Made on 980409. Commitment Is Made to Submit Rev to Fermi 1 SAR

Submits Voluntary LER 98-001 Containing Info of Interest to NRC Which Did Not Specifically Meet Reporting Criteria of Section I.8 of Fermi 1 Ts.Notification Was Made on 980409. Commitment Is Made to Submit Rev to Fermi 1 SAR

ML20216B207
Person / Time
Site:	Fermi
Issue date:	05/08/1998
From:	Gipson D DETROIT EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-98-0087, CON-NRC-98-87 NUDOCS 9805150091
Download: ML20216B207 (6)

LER-2098-001, Submits Voluntary LER 98-001 Containing Info of Interest to NRC Which Did Not Specifically Meet Reporting Criteria of Section I.8 of Fermi 1 Ts.Notification Was Made on 980409. Commitment Is Made to Submit Rev to Fermi 1 SAR

Event date:
Report date:
0162098001R00 - NRC Website

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4 Douglas R. Gipson Senior Vice President Nuclear Generation Fermi 2 6400 North Di.xie liwy, Newport, Michigan 48166 Tel: 313M61d01 Fax 313.586.417z Detroit Edison May 8,1998 NRC-98-0087 U. S. Nuclear Regulatory Commission Attn.: Document Control Desk Washington, D. C. 20555 ,

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References:

1) Enrico Fermi Atomic Power Plant, Unit No.1 NRC Docket No. 50-16 NRC License Number DPR-9

2) " Application for a License Amendment -

Fermi 1 Safety Analysis Report",

NRC-97-0115, dated December 15,1997

Subject:

Voluntary Licensee Event Report (LEP)

No.98-001 Detroit Edison is submitting this voluntary Licensee Event Report containing information ofinterest to the NRC which did not specifically meet the reporting criteria of Section I.8 of the Fermi 1 Technical Specifications. The verbal notification was made to D. Nelson of NRC Region III at 12:30 on April 9,1998. >

Fermi 1 was a sodium-cooled, fast breeder reactor permanently shut down in 1972 and is currently in SAFSTOR status. During the decommissioning process, almost all the sodium was removed from plant systems; however, a residual amount of sodium remains.

In December 1997 (Reference 2), Detroit Edison submitted a Final Safety Analysis Report to the NRC on the Fermi I facility, in accordance with the Decommissioning l Rule. Reference 2 discussed that it had recently come to Detroit Edison's attention  !

that sodium-cooled breeder reactors typically have a small quantity of tritium in the ]'

secondary sodium. The existing documentation for Fermi 1 describes the secondary sodium as non-radioactive. Detroit Edison decided to analyze samples of secondary I i 9805150091 990508 gg. < j DR ADOCK O

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A DTI: Energy Company l 1

USNRC NRC-98-0087 Page 2 i

sodium for tritium. Reference 2 stated that if tritium is identified, the NRC will be l- notified and the Fermi 1 Safety Analysis Report and the secondary sodium safety evaluation would be revised accordingly. This letter provides the notification. The attached report describes the results of the analysis, actions taken, and potential )

, consequences. Detroit Edison is preparing an update to the Fermi 1 Safety Analysis Report for submittal to the NRC.

The only commitment being made in this letter is to submit a revision to the Fermi 1 Safety Analysis Report. If there are any questions, please contact Lynne Goodman,-

Director, Fermi 1 at (734) 586-1205. ,

Sincerely, Attachment cc: A.B. Bea:h S.W. Brown G.A. Harris B. Jorgensen P. Lee

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• USNRC NRC-98-0087 L Page 3 bec: P. Fessler D.R. Gipson L.S. Goodman L.K. Layton J.E. Moyers D.K. Cobb J.E. Conen i L. Craine l R.R. Eberhardt, Jr. l D. Ferencz l W.D. Gilbert )

R.A. Janssens l E.F. Kokosky R. Laubenstein E.F. Madsen i R.L. Matthews i R.H. McLenon  ;

J.E. Meyers j R.A. Newkirk l W.T. O'Connor, Jr.

E.M. Page i K.W. Sessions  !

E.M. Wilds l D.R. Williams Information Management (116 NOC) - Fermi 1 Records NRR Chron File (Licensing)

NRC Notebook (Fermi 1) 1 l

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5-i I

Attachment to NRC-98-0087 l

Pag:!

, . Tritium in Secondary Sodium at Fermi 1 Purpose The purpose of this briefing paper is to communicate with the NRC information regarding tritium results obtained for secondary sodium samples taken from Fermi I piping. The criteria in the Fermi 1 Technical Specifications that require reporting to the NRC are not literally met; however, Detroit Edison has decided to voluntarily report this information update.

Backeround Detroit Edison is performing an Industrial Safety Improvement Project at Fermi 1, which was an experimental breeder reactor owned and operated by the Power Reactor Development Company (PRDC). The facility has been shut down since 1972. Detroit Edison assumed ownership in 1976 after the original decommissioning was completed.

One of the activities of the Industrial Safety Improvement Project is to remove sodium residues remaining in plant systems left when the bulk sodium was drained and siphoned from the plant systems in 1973. To prepare for this activity, Detroit Edison is consulting with sodium experts, and visiting sodium facilities to obtain operating experiences and lessons leamed, in order to be able to best perform this activity. In October 1997, information was obtained at CEA's Cadarache facility in France that breeder reactors' secondary sodium typically contains tritium.

Tritium diffuses from the primary sodium through the heat exchanger walls to the secondary sodium. Tritium has also been detected in the secondary sodium at EBR-II in Idaho.

At Fermi 1, the secondary sodium system removed heat from the Intermediate Heat Exchangers in the Reactor Building and transferred it to the Steam Generators in the Steam Generator Building where it was used to produce steam for turbine operations. This sodium did not pass through the reactor.

During the original decommissioning, samples were taken from each secondary sodium loop and analyzed in June 1973 for radioactivity and impurities. Some samples were sent to Hanford Engineering Development Laboratory and the University of Michigan, while others were analyzed by PRDC, the licensee. The level of beta radioactivity in all samples was reported in the Retirement Report as being no higher than the activity in naturally occurring isotopes found in regular commercial grade clean (radiologically non-contaminated) sodium. The secondary sodium (about 30,400 gallons) was shipped offsite in 1973 to be processed into sodium methylate. The draining and shipping evolution was performed in a planned, controlled manner after the cc .firmation from three independent laboratories that the sodium was not radiologically contaminated. This was performed in accordance with existing regulatory requirements.

Estimates ofremaining secondary sodium in the Steam Generator Building vary, with the most likely being 225 - 285 gallons, and one reference leading to a 725 gallon estimate.

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,i Attachment to NRC-98-0087 Page 2.-

D'etroit 8dison reviewed the documentation available on the secondary sodium analyses from l 1973. It was summary level information and did not specifically address individual isotopes I L evaluated, including whether tritium was addressed. As a conservative measure, Detroit Edison l then decided to sample and analyze the residual secondary sodium for tritium. Advances in technology and radiochemical techniques over the past 25 years has enabled an independent lab to determine the presence of tritium. The cover letter submitting the Fermi 1 Safety Analysis l Report acknowledged the potential for tritium to be present and stated that the NRC would be informed if tritium were detected. Three samples were taken in January 1998 and sent to l

Argonne National Laboratory -West to be analyzed.

l Analysis Results L

On April 2,1998, the sample analysis results were faxed to Fermi 1. Analysis results showed tritium was present in the samples. Sample No. I was analyzed to have approximately 1E-2 Ci/gm, while the other sample results were about 1E-4 Ci/gm. Based on the possibility of light affecting the scintillation analysis results, the samples were kept in the dark for greater than ,

24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and then recounted. The recount results were received April 8,1998 and showed  !

similar data. A team of Fermi 2 Radiation Protection personnel and Fermi 1 personnel evaluated l

the information, and prepared an action plan. j l

Actions Taken i i

[- i l An air sample of the Steam Generator Building atmosphere was taken and analyzed April 6, q L 1998 as a conservative measure. No tritium was detected. During the Industrial Safety 1 l Improvement Project, access to the Steam Generator Building, which is outside the Protected l Area, requires the Fermi 1 Custodian's or Custodial Delegate's permission and a safety brief ,

l prior to entry. An additional sign has been posted requiring Radiation Protection to be contacted i prior to breaching any piping or component in the Steam Generator Building. Radiation surveys performed in the Steam Generator Building show doses to be at background levels and 'no loose I surface contamination present.

' A sodium expert was consulted on the potential behavior of tritium in sodium. This expert stated I

. that since sodium hydride (NaH) forms in sodium, the tritium in the sodium would be in the form of NaH. NaH would tend to adhere to pipe walls or settle in the bottom of the piping in areas where the system is cooler and be removed by the cold trap purification system. The sample with the highest result did come from a small pipe that would be cooler than most of the system.

p When NaH reacts with water or alcohol, the hydrogen (or tritium) would be released as a gas.

Similar information was received from CEA in France. During cooling of a sodium circuit, l

especially during the change from liquid to solid, tritium goes first to the cold point. They have seen factors of 100 between tube surface and sodium bulk tritium content. Bulk sodium was drained from Fermi l's secondary system in 1973, only solid sodium residues remain.

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Attachment to NRC-98-0087 -

Page 3 Since the range of the recent sample results was greater than originally expected, additional samples were taken from piping near the January 1998 sample points. Detroit Edison is awaiting the results of these sample analyses.

Radioloelcal Conscauences The potential radiological consequences of a non-mechanistic event resulting in the release of all the tritium contained in the secondary sodium in the Steam Generator Building have been conservatively assessed. Since the sodium residues are contained within three separate storage tanks and various piping, the release was assumed to take place over an extended period.

Assumptions from the Fermi 1 licensing basis accident analysis for the primary sodium postulated accident were used. Assuming 725 gallons of sodium at the highest tritium concentration analyzed are released, the resulting maximum dose to a member of the public at )

the site boundary was estimated to be less than 0.00002 mrem, which is indistinguishable from background radiation levels.

I Addressing the potential release from the processing of the 30,400 gallons of sodium into sodium methylate, after it was shipped offsite, using conservative assumptions, such as adjusting tritium concentration back to 1973, the maximum dose to a member of the public was estimated to be less than 0.1 mrem.

Likely Cause As discussed above, tritium diffused through the heat exchanger walls from the primary sodium j to the secondary sodium. There is no evidence ofIntermediate Heat Exchanger tube leakage I during open. Con of Fermi 1. It is possible that no tritium analysis was performed in 1973 or I during plant operation due to lack of awareness of the ability of tritium to penetrate tube walls. It is also possible that a tritium analysis was performed, but tritium was not detected in the bulk sodium sampled. A 1983 memo does mention a tritium analysis performed in 1975 that measured tritium content slightly above the detectable limit, but only residual secondary sodium {

remained at Fermi 1 in 1975. The thorough analysis performed for other beta activity indicates )

the licensee was conscientious in attempting to provide reasonable assurance that the secondary  :)

sodium was radiologically clean during the system decommissioning in 1973.

Conclusion i Tritium has been detected in samples of Fermi l's secondary sodium residues remaining in the system piping. The samples were taken based on operating experience learned from another facility during prep ration for the Industrial Safety Improvement Project. The Project includes removing the sodium residues. A conservative radiological dose assessment shows the amount of tritium present at Fermi 1 in its secondary sodium residues could result in radiation doses less than 0.0001% of the 10 CFR 20 annual limit for a member of the public. Therefore, the sodium residues presented no hazard to the health and safety of the public in the past and will not in the future.

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