ML19338B912
| ML19338B912 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/20/1980 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| NUDOCS 8003250865 | |
| Download: ML19338B912 (4) | |
Text
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i The Commiissioners l-M:
I Harold R. Denton, DirectorOffice of Nuclear Re
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Executive Director for Operations ERSONNEL AIR RELEASE OF KRYPTON GAS IN REACTOR BU M:
Subject:
LOCK AT THI-2 f kiypton-85
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Approval of release of a de minimus quantity o look in the gas to allow entry into the personnel air
Purpose:
TMI-2 reactor building.
data related As part of the licensee's program to gatherin the TMI-2 reactor i
to radiation and contamination levels building, This entry would allow sensitive mon Discussion:
i of the equipment to measure the intensity and spectrum planned.
ir lock radiation penetrating the window of the inner aS the latter entry into the reactor building itself, whether krypton in door.
entry is prior to or following disposal of the the reactor building.
dures The on-site NRC staff has reviewed the detailed proce from the for the air lock entry and finds them acceptaDie ll as worker standpoint of public health and safety as weThese p It has long been protection.
f krypton-85 air lock atmosphere prior *.o entry.
recognized, hcNever, tha*. a small amount of about 40 milli-was trapped in the air lock (a total ocurie ly Ct/cc in tne
.aci/cc compared to about 1 xThis activity reached 2 x 10' reactor building).
wnile the reactor building was pressur z ns. Because and/or by diffusion during the suosequent ting of the i
lock can be reactor building atmosphere, of which the a r
Contact:
R. Vollmer, NRR s o n s a r> o h s-49-27347 u-A
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t The Commissioners l
considered a part, albeit a very small one, approval to proceed with the entry was not given.
There are several ways to approach this entry vis-a-vis the krypton gas.
At these concentrations the workers could enter as is, but of course much of the gas would escape &Jring the 1.
personnel and equipment entry process, s
The air lock atmosphere could be purged into the reactor building, which is still at a negative pressure relativeH 2.
i to atmosphere.
concentration in the air lock to HPC by a feed-and-Dieed i
i operation, this would add about 10,000 cubic feet of air f
into the reactor builoing, thereby slightly decreasing the margin below atmospheric and increasing the likeli-hood of positive reactor building when warm weather comes.
urged into compressed f
The air lock atmosphere could be g j
air bottles (20 to 30) and held for eventual disposal.
3.
i Finally, the air lock atmosphere could be purged through filters to the plant exhaust which would assure that any 4.
particulates (none have been measured in the samples) would be retained but the krypton would not be held.
i We have evaluated the concentration of krypton-85 at the plant vent exit for option 4 and find that it would b 1
The maximum off-site indi-at the nearest site boundary.
vidual total body dose associated with releasing all the Kr-85 contained in the air lock would be less than The dose rate due to natural background 0.1 /2res.
Therefore, the dose radiation is more than 10.urem/hr.
associated with the Kr-85 release is equivalent to less
- Further, than 1 minute exposure to natural Dackground.
greater amounts of krypton-85 are Deing routinely ais-charged through the steam generator turoine exhaust patn-Therefore, we believe the way (refer to PN THI-79-08).
release resulting from option 4 should be considered de minimus and that options 1-3, while offering the poten-tial for reduction in release, need not be consicered further.
Since it is likely that a decision on disposal of the reactor building krypton is at least several months away, the
The Commissioners.
licensee is planning an exploratory entry into the reactor building in March or April to make more definitive radia-tion measurements and take photos and s imples of contam-inated surfaces. This entry would aisc cause the release of some krypton by exchange of atmo?f!ere when opening and closing the inner air lock door. However, we believe that these entries can be conducted in a safe and environmen-tally acceptable manner, and that the infonnation gained will be useful in assuring that the decontamination plans minimize operator exposure and environmental impact.
Recomendation: The Commission approve the discharge of a de minimus, level of krypton-85 prior to entry into the reactor building air lock.
Coordination:
The Office of the Executive Legal Director has no legal objection.
Ursw w q w & 8. Destes Harold R. Denton, Director Office of Nuclear Reactor Regulation l
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GeQC FORM 31819 76) NRCM O240 Dil S GOVE AN=*ENT opeNTING OFFICE r 1979 289-369
The Conssissioners /
these entries can be conducted in a safe and environmen-tally acceptable manner, and that the information gained will be useful in assuring that the decontamination plans minimize operator exposure and environmental,Ampact.
Recommendation: The Coassission approve the discharge of &de miniwm level of krypton-85 prior to entry into the reactor building air lock.
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Coordination:
Tha Office of the Executive Legal Director has no legal objection.
Harold R. Denton, Director Office of Nuclear Reactor Regulation l
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