Re: FW: Message requesting help on temporary shielding

["Erik F. Shores" <eshores@LANL.GOV>]

At 11:41 AM 9/25/01 -0700, Jerald_L_Eby@RL.GOV wrote:

> > Subject:      Message requesting help on temporary shielding

> >

> > Folks, the following message requests help in solving a temporary

> > shielding problem at our Pu facility.  If there is someone at your Site

> > that could offer some suggestions we would really appreciate a response.

> > We will be glad to share the responses and  the actions we take to solve

> > this problem.

> >

> >

> > "At Hanford, we are experiencing elevated neutron and gamma radiation

> > levels in a room used to store Special Nuclear Material (SNM).  Source of

> > the radiation is from containers of SNM stored inside a cage.  We would

> > like to eliminate the gamma radiation and reduce the neutron radiation.

> > Our plan is to install temporary shielding on, or adjacent to, the sides

> > of the cage to a height of about 6' for a total distance of about 26'.

> > This section of the cage also includes an entrance gate.  We are

> > tentatively planning on having someone fabricate a stainless steel

> > "sandwich" with borated polyethylene inside.  The borated poly will be 1"

> > thick and the stainless steel will be 1/4" thick.  We are concerned that

> > the 1" thickness of borated poly may not be enough to effectively

> > attenuate the neutrons.  Concerns from the plant include seismic, floor

> > loading, and the need to be non-combustible.  The final product can not

> > ignite, burn, support combustion, or release flammable vapors, when

> > subjected to fire or heat.

> >

> > We suspect that someone else has already encountered this same problem and

> > has taken action to solve it.  If anyone knows of better materials or

> > methods of providing temporary shielding that will attenuate the neutron

> > and gamma radiation, please get in contact with the Hanford ALARA Center

> > or Greg Hauger at the address/phone shown below.  We are also interested

> > in finding a vendor that has the resources to fabricate this type of

> > shielding.  Our plan is to install additional sections of the shielding in

> > several other areas if it proves to be effective."



Greetings,



Your aforementioned concerns present some interesting challenges. Similar 

work has been done at Los Alamos. You may be interested in LA-UR-01-2266 

"Shielding Design for a Plutonium Oxide Storage Room" located at the 

following URL:



http://lib-www.lanl.gov/la-pubs/00367046.pdf



This work used the Monte Carlo code MCNP to determine dose rates from a 

proposed shielding configuration. The shield was very similar to the above 

described sandwich (although it was 5 cm of borated poly as opposed to one 

inch).



Please look over the report and let me know if you'd like further 

information. If so, I'll put you in contact with the person in charge of 

the project for answers regarding manufacturers, etc. Incidentally, I'd be 

interested in any comments regarding the LA-report.



Regards,

Erik

________________________________________

Erik F. Shores

Los Alamos National Laboratory

ESH-12, Radiological Engineering Team

Mailto:eshores@lanl.gov

505.665.7643 (phone)

505.667.9726 (facsimile) 



************************************************************************

You are currently subscribed to the Radsafe mailing list. To unsubscribe,

send an e-mail to Majordomo@list.vanderbilt.edu  Put the text "unsubscribe

radsafe" (no quote marks) in the body of the e-mail, with no subject line.