Reac. Memos
Notebook
FURTHER NOTES ON CHARACTERISTICS OF N. C. STATE RESEARCH REACTOR
At upper limit may be calculated for the quantity of longlived fission
ucts
Element  Boiling Point  Half Life  Fission Yield (f)  Disintegrations/second from Total Amt. Produced in 10 years (= 1.4 x 103) (3x1010) P(watts) f(1e .693t/[lambda]) 
Kr85  gas  10 y  0.24%  3.9 x 108 
Rb87  700°  6.3x1010y  3. %  Negativeligible 
Csl37  670°  33 y  6. %  2. x 1010 
The activity on the building wall at the end of ten years is then
Kr85: 3.9 x 108 x 0.05%  = .2 x 106 disintegrations/sec. 
Cs137: 2 x 1010 x 10% x 0.05%  = 1 x 106 
Total  = 1.2 x 106 disintegrations/sec/5 x 105 cm² 
= 1.2 x 106 = 2.4 disintegrations/sec/cm²  
5 x 105 
If the reactor is "shutdown" and the cooling water is cut off simultaneously,
there is the possibility of a rise in temperature due to the activity of the fission
products. The power due to the activity of [beta] and [gamma] rays from the fission products is
given by (Way and Wigner)
where f is the previous rate of use of uranium, T is the previous operation time of the
reactor and t is the time after shutdown. At 10 KW f [~=] 1/100 gms/day. Assume that
T = 100 days and t = 0.001 (about 1 1/2 minutes). Then
E (T,t) = 225 watts.
Calculations on the conduction of heat through the graphite, assuming reactor
temperature, Tr 80°C and temperature at end of graphite reflector, Tt 20°C,
cate
The reactor temperature, therefore, will decrease after shutdown, whether the
cooling water continues to flow or not.
If, due to sabotage, a non nuclear explosion should vaporize 50% of the fission
products accumulated in the reactor, an approximation may he made of the radiation
exposure hazard which could result.
The hazard is calculated for two possible cases: 1. The explosion causes
formation of a small cloud near ground level, which subsequently drifts away. The
cloud in assumed to spread laterally 1/7th the distance of downwind travel. 2. The
explosion causes formation in the reactor room of a cloud which is exhausted through
the building stack (150 feet high). The cloud subsequently drifts away from the top
of the stack, spreading as above.
Assumptions:
1. Reactor has operated steadily at 5 KW.  
2. Wind velocity is 2 m/hr.  
3. Range of [beta] = 5ft; of [gamma] = 1000 ft.  
4. Exposure (Roentgens) = 2 x 1010 

Case 1. Cloud is formed near groundlevel and drifts toward a man 200 feet away. The
man's exposure is
Case 2. Cloud is dispersed from top of 150 foot stack and reaches ground level at 1050
feet. A man's exposure at 1050 feet, at the point the cloud reaches ground
level, is
The daily tolerance level of
0.1 r/8 hours. Each or the following fluxes will result in approximately 0.1 r/8 hrs:
80  2 Mev  [beta]'s/cm² sec. 
270  2 Mev  n's/cm² sec. 
3300  2 Mev  [gamma]'s/cm² sec. 
46,500  1/40 ev  n's/cm² sec. 
Plutonium tolerance  5 x 105 [mu] grams/cc in drinking water
Drinking water tolerance 106 curries/cu ft.
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270 n/cm²/sec 0.1r in 8 hrs.
2x1018 n/sec
Father Joseph Lynch, Fordham
Earthquakes