RE: Steam Generator Replacement Calculations

[Emil Murat <kerrembaev@yahoo.com>]

Diana,

In my opinion, to worry about a radiation dose while
Steam Generator is falling down is little bit
of....over cautious.

Well, sometimes I can be a smart as.....anybody else.
 
Do we need to worry about a worker is being over
exposed to the radiation from the fall of a HUGE chunk
of metal with a few hundreds of millirems/hr dose rate
on the outside of it? 

I. To aside from the subject.

1.0 DURING Chernobyl accident ONLY one person has died
or to be more accurate, was/is MIA (missing in
actions) inside of RCS reactor's cooling system pump
room.

1.1 There is no evidence how, when, if  or so that
technician actually have died. 
(body never was recovered)..

Nevertheless,
 
1.2. If he have died (no doubts in my mind) 
Then
1.2.1 Was it from the over exposure to the radiation? 
or 
1.2.2 As a result of conventional physical injury and
following to it dehydration and hunger?

1.2.3 It is hard to determine.

II. Speculations:

2.1. At first HE was injured and trapped and then it
was impossible to rescue him for one or another
reason.......
2.1.1 Personally, I would like to think that he rather
died instantly from something big falling right on
him.

III. Versions:

Official:
3.1 : Dose rates: multiple Rads/hr were the primary
and official reason for.....the lack of efforts or
impossible task?. Who knows?

Mine:

3.2 I think, in addition to 3.1, also because there
was a VERY SLOW process of REALIZATION of the
accident's magnitude and associated with it emergency
response team On-site actions in the part of counting
plant's workers on duty. 

IV. Suggestions:

4.1. If you still want/need to do 10cfr20 calcs for
the replacement,

4.2 Get a some ball park ideas(worst case scenario's)
from your mechanical engineers, what will be the
mechanical impacts to the Vapor Containment's
structures in case of Steam Generator's drop
(mechanical engineers should estimate a possible
drop's impact of the drop onto Containment's
Structures).

4.3. Estimate changes of A Radioactive Source
configuration.

REMEMBER! There won't be fuel in your reactor, while
the Steam Generator is moving. So you do not have to
worry about the "big guns".


4.4 Calculate new dose RATES.

4.5. Look into the different situations as a trapped
or injured worker, rescue efforts for the TIME and
DISTANCE.

4.6. The rest, I am sure you know how to do.

In addition,

5.1 You may as well consider 10cfr20's posting
requirements, while you are getting into the new dose
rates, anyway.

5.2 Well, if after that you still want to write a
COMPLETE radiological review prior to the replacement,
you may want to look at 10cfr20's instantaneous limits
and 10cfr50's accumulative limits for potential
radioactive effluents in case if something get
OFF-SITE into the environment as the result of the
potential drop.

5.3 Your Technical Specification limits, I am sure,
you know.


Regards,

Emil.



You wrote:
>>
For those power reactor people who have done steam
generator replacements,
did you document a calculation demonstrating
compliance with 10 CFR 20
occupational dose limits for the scenario of a drop of
a steam generator in
containment.  If so please provide a contact if
possible.Diana Nissen



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