ML20085J385

Forwards Rept to NRC on Determination of EALs & Air Monitoring Sys Alarm Setpoints at Tx A&M Univ Nuclear Science Ctr (Nsc).Rept Justifies NSC Revised Emergency Plan

ML20085J385
Person / Time
Site:	Texas A&M University
Issue date:	06/14/1995
From:	Okelly S TEXAS A&M UNIV., COLLEGE STATION, TX
To:	Michaels T NRC (Affiliation Not Assigned)
References
NUDOCS 9506220145
Download: ML20085J385 (5)

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TEX A S ;E N GI N E E RING EXPE RI.\1 ENT STATION ,

TEXAS A&M UNIVERSITY ,

COLLEGE STATION, TEXAS 77843-3575 1

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NUCLEAR SCIENCE CENTER 409/845-7551 .

14 June 1995 i

.95-0212 i Dr. Theodore S. Michaels, Senior Project Manager  !

Non-Power Reactors and Decommissioning  !

Project Directorate  ;

Division of Project Support Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 .

SUBJECT:

Emergency Plan EAL Justification Report

Dear Dr. Michaels:

Several weeks-ago you asked that I prepare a report justifying the Nuclear Science Center revised Emergency. Plan. The completed.

report is attached for your review. Please call me if you have any questions concerning our conclusions.  ;

I will be submitting a minor revision of the Plan to our Reactor [

Safety Board this August. If the Commission requires further- ,

changes to our Emergency Plan, I would like to include them at that time.

Respe tfull [

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/ l Sean O'Ke y Assistant Director SOK/sjm Attachments xc: 12110/ Central File File #17122 i

I 9506220145 950614 i PDR ADOCK 05000059 /

F PDR J RESEARCH AND DEVELOPMENT FOR MANKIND \

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Report to the Nuclear Regulatory Conunission on the Determination of Emergency Action Levels and Air Monitoring System Alarm Setpoints at the Texas A&M University Nuclear Science Center Introduction During an NRC inspection at the Nuclear Science Center (NSC) in March of 1993, a weakness in the facility emergency preparedness was reported (1). The weakness was a failure to establish Emergency Action Levels (EALs) which were-related to facility parameters and which could be promptly assessed. It was noted by the inspectors that the EAL for NOUE'and Alert were orders of magnitude above the full scale indication available to operators.

The NSC staff revised the facility Emergency Plan in August of 1994 to allow operators to declar emergencies based on available parameters. EALs were baseo on air monitor alarm setpoints which are derived from restricted and unrestricted area limits in 10 CFR 20, Table 2.

The NRC, after reviewing the revised Emergency Plan, requested that the NSC modify the plan such that EALs were based on levels that resulted in the declaration of a NOUE or Alert. The following is a justification for the NSC Emergency Plan remaining as it is currently written.

Design Basis Accident The Design Basis Accident (DBA) in the facility Safety Analysis Report (SAR)is the loss of integrity of the fuel cladding for one element and the simultaneous loss of pool water resulting in fission product release (2). In the Safety Evaluation Report (SER) (NUREG-0947) prepared in 1983, the DBA was termed a " Fuel Handling Scenario" and resulted in the fission products contained within a single fuel element being released to the confinement building (3).

The exposures calculated at the site boundary (12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after release) from the two reports are summarized below.

Whole Body Dose Thyroid Dose SAR 0.021 mrem 18 mrem SER 0.1 mrem 18 mrem i

The analysis of the DBA is summarized in the SER as follows:

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...a single fuel rod cladding failure will produce exposures that are small fractions of 10 CFR 20 and that even if several fuel rods failed at once, the expected dose equivalents in unrestricted areas would still be well below 10 CFR 20 limits."

The NSC reactor is the largest potential source of radioactive material that could be released into the building and subsequently to the environment, therefore, it may be concluded that the risk is minimal.

Argon-41 Production and Experiment Failure The Ar-41 production rate at the facility during normal operation is calculated to be less than 1.0E2 pCi/ min from all reactor related sources (4). The building exhaust rate of 2.2E8 ml/ min gives an upper bound to the steady-state Ar-41 production to be 4.5E-7 pCi/ml. A 200:1 dilution at the site boundary results in continuous exposure at the site boundary of 2.25E-9 pCi/ml(5) . The NSC rarely operates the reactor on a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> schedule, therefore this is a conservative value and below the limits of 10 CFR 20.

The NSC routinely handles up to 5 Ci of Ar-41 for commercial applications. A lupture of the experiment device would be discovered while venting the secondary encapsulation directly to the building exhaust. This can be assumed to release the total activity directly to the environment. The building exhaust rate is measured to be 2.2E8 ml/ min.

Assuming the release occurred during a one minute venting, this would produce a maximum release of 2.27E-2 pCi/ml.

Using the dilution factor of 200 from the SAR, the concentration at the site boundary would be 1.135E-4 pCi/ml.

This would be averaged with the steady-state production to give a release in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of 8.1E-8 pCi/ml. This value is above that allowed in Table 2 of 10 CFR 20 Appendix B, however, it is still below the limit for an Unusual Event.

Determination of Effluent Monitor Alarm Setpoints The NSC stack particulate monitor is intended to alarm on l high concentrations of Cs-137. The limit from Table 2, j Column 1 is 2E-10 pCi/ml. Applying a dilution factor of 200 will give a maximum allowed concentration of 4E-8 pCi/ml at the building exhaust monitor. Using the instrument conversion factor this value equates to a meter reading of I 6190 cps. The highest value that the operator can read on I the current equipment is 10K cps. The NSC staff required the alarm setpoints be such that operators could take action 2

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. 1 before exceeding the effluent limit. Therefore, the setpoint is 3095 cps to allow the time for the operator to respond.

The NSC stack gas monitor is calibrated for detection of Ar-

41. The limit of 10 CFR 20 is lE-8 pCi/ml at the site boundary. Application of the dilution factor and the calibration conversion factor will require an indication of 12 cps on the meter to cause an alarm. A NOUE and Alert would require levels of 593 cps and 2966 cps respectively.

Determination of EALs The NSC Emergency Plan was revised to remove EALs based on j those calculations that resulted in unrealistic concentrations from the NSC building exhaust. These levels had been proven to be unattainable by any credible scenario at the facility. The NSC staff concluded that any release of reactor fission products in the restricted area should require a higher level of emergency actions. Therefore, an alarm on the fission product monitor (Channel 2) would require a Notification of Unusual Event emergency level. It should be noted that this is not based on a hazard to the general public, but rather to initiate reporting l requirements of 10 CFR 50. I l

Conclusion ,

l It is the opinion of the NSC staff that there is currently l no conceivable instance that would produce the site boundary levels required to initiate emergency actions for an Unusual Event or an Alert at the NSC. Therefore, it is requested that the NSC Emergency Plan remain as written with regard to this matter.

References l

1. NRC Inspection Report 50-128/93-01, Dated April 9, 1995.

2. Facility Operating License (R-83) Safety Analysis Report, Chapter 10, " Radiation Protection and Radioactive Effluents", Section E, Dilution Factor Calculations.

3. Safety Evaluation Report Related to Renewal of the Operating License for the Texas A&M University Research Reactor, NUREG-0947, Section 14.7, Handling Irradiated Fuel, Office of Nuclear Reactor Regulation, March 1983 3

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4. Walker, J.D. Randall, D.E. Feltz, and E. F. Bates,

" Determination of Argon-41 Production at the Texas

.A&M Nuclear Science Center Reactor", Nuclear Science Center Technical Paper Number 32, 1975.

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