ML11271A054

Reed College, Clarifications in Response to Phone Calls on July 7, 2011, and July 15, 2011

ML11271A054
Person / Time
Site:	Reed College
Issue date:	09/21/2011
From:	Krahenbuhl M Reed College
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML11271A054 (3)

Text

MA REED COLLEGE REACTOR FACILITY 3203 Southeast Woodstock Boulevard September 21, 2011 Portland, Oregon 97202-8199 Document Control Desk telephone U.S. Nuclear Regulatory Commission 503/777-7222 Washington, DC 20555-0001 fax Docket: 50-288 503/777-7274 License No: R- 112 e..uil RE: Clarifications in Response to phone calls on July 7, 2011, and July 15,2011 reactor@reed.edu web The following is a clarification as requested in phone calls on July 7, 2011 and http://reactor.reed.edu July 15, 2011.

RIA 36. Demonstrate that there is no room-to-room leakage that results in an inhalation exposure to an individual in the psychology building. Confirm that the assumptions are sufficiently conservative. Link the evacuation time in the Emergency Plan to the postulated doses.

RRR response:

The reactor facility is connected to the psychology building via a single door.

Additionally, there are 4 intervening spaces and a flight of stairs prior to the connecting door. During normal ventilation operations, the leak rate from the psychology building into the reactor facility was measured using TSITM VelociCalc calibrated Sept 2010. The leak rate around the closed locked door ranged from 3 cfm to 300 cfm (0.001-0.142 m 3/s). When the ventilation system is operating in isolation mode, the leak rate into the reactor facility will increase. If both the psychology building and the reactor facility lose power to their respective HVAC systems, there is no pressure differential to drive room-to-room leakage.

Any room-to-room leakage would be the result of random motion.

However in the unlikely event that the cladding on a single fuel element fails in air and the air flow reverses direction, i.e. air leaks from the reactor facility into the psychology building, the total effective dose equivalent resulting from room to room leakage to an individual standing at the connecting doorway was estimated using two leak rates. The TEDE for varying exposure durations are in the Table 1.

Table 1. The TEDE for varying exposure durations Leak 0.00154 m 3/sec 0.142 m3/s rate: 3.26 ft3/m 300 ft3/m Time (mrem) (mrem) 1 minute 9.01E-15 4.92E-7 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 5.82E-6 0.128 J day 1.66 3.09 1 week 21.6 21.6 30 days 92.6 92.6 10 CFR 20 requires the general population TEDE to be below 100 mremlyear and less than 2 mrem in an hour. A fuel cladding failure in air at Reed College cannot generate 2 mrem in a single hour dose at the connecting door between the reactor facility and the psychology building. Additionally, the 100 mrem threshold is reached at 32 days. Based on these estimated doses, immediate evacuation of the psychology building is unnecessary. Table 2 contains duration of exposure to reach regulatory limits for the general population.

Table 2. Exposure time required to reach regulatory dose limits for the general public as a result of a cladding failure in air.

0.00154 m3 /sec 0.142 mj/s Leak rate: 3.26 ft3/m 300 ft3/m 2 mrem 26.18 hours2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br /> 15.56 hours6.481481e-4 days <br />0.0156 hours <br />9.259259e-5 weeks <br />2.1308e-5 months <br /> 100 mrem 32.39 days 32.39 days Methodology and Assumptions The following assumptions were used:

" The cladding failure occurs at time=0 and the individual is continuously standing at the doorway.

" The rooms between the reactor bay and the stairway were modeled as a series of ideal continuous stirred-tank reactor (Levenspiel 1999).

o The exiting concentration of the isotope is assumed to be the average concentration of the isotope, in the space.

• The source term is the highest burned element as described in the May 2011 response to the request for additional information.

• The concentration for the isotope of interest was converted into TEDE using DOE /EH-0071.

• The model does not take credit for radioactive decay, which would further reduce the postulated dose.

• Locations and room designations are consistent with Figure 1 of the RRR Security Plan' dated (07/22/09).

• Table 3 contains abbreviations and parameters used to estimate the dose.

The equation used to determine the concentration of each isotope at the connecting door is:

CicD(t) = Ci,B (1 - e-J )(1--

- e-ITcR - e-' IT, )(1 - e-"Tc )(1 - e-1TBR C=concentration of the isotope i=isotope of interest It = the time from the initiation of the event Tr = the residence time where V

Q V = free air volume Q = leak rate Table 3. Abbreviations and parameters used for estimating the dose to an individual located at the connection door.

Abbreviation Location Free Residence time Residence time volume Q=0.00154 m 3/sec Q=0.142 m3/sec (m3 (seconds) (seconds)

CD Connecting door - G -

B Reactor bay - C008 300 194805 2113 CR Control room 59 C006 38312 415 H Exit Hallway 43 27922 303 C Classroom C005B 100 64935 704 BR Break room +Lab +Sump 67 C003+C004+C005 43506 472 Chemical Reaction Engineering, 0. Levenspiel, John Wiley & Sons, 1999.

"Internal dose conversion factors for calculation of dose to the public," DOE/EH-0071, U.S. Department of Energy, Washington, D.C., 1988 I declare under penalty of perjury that the foregoing is true and correct.

Executed on 4K Z/ 2.41/

Melinda P. Krahenbuhl, Ph.D.

Director, Reed Research Reactor.