[ RadSafe ] neutron sources for Cl-38 production

[Derek Putley]

Arvic / All
 
See below for a quote from one of your links:-
 
"Chlorine-38, which has a half-life of only 37 minutes, is created when
stable chlorine-37, which is about one-fourth of the chlorine in salt,
absorbs a neutron. Since seawater has been used to cool [the reactors],
there is now a large amount of salt * thousands of kilograms * in all
three reactors. 
 
Now, if a reactor is truly shut down, there is only one source of
neutrons * spontaneous fission of some heavy metals that are created
when the reactor is working that are present in the reactor fuel. 
 
The most important ones are two isotopes of plutonium and two of
curium. 
But if accidental chain reactions are occurring, it means that the
efforts to completely shut down the reactor by mixing boron with the
seawater have not completely succeeded. Periodic criticalities, or even
a single accidental one, would mean that highly radioactive fission and
activation products are being (or have been) created at least in Unit 1
since it was shut down. It would also mean that one or more intense
bursts of neutrons, which cause heavy radiation damage to people, have
occurred and possibly could occur again, unless the mechanism is
understood and measures taken to prevent it. Measures would also need to
be taken to protect workers and to measure potential neutron and gamma
radiation exposure."
 
 
I've not done any sums to evaluate the magnitude of the effects, but I
do believe the 3rd paragraph in above quoted text has ignored neutron
production by means of (alpha, n) reactions. Some general background on
(alpha,n) sources can be found here:-
 
http://en.wikipedia.org/wiki/Neutron_source 
 
and an on-line calculator is available here:-
 
http://www.wise-uranium.org/ranch.html 
 
 
Message: 7
Date: Fri, 1 Apr 2011 15:07:34 +0100
From: "Arvic Harms" <Arvic.Harms at npl.co.uk>
Subject: Re: [ RadSafe ] Radioactive contamination  of the ocean
To: "The International Radiation Protection (Health Physics) Mailing
List"<radsafe at health.phys.iit.edu>
Message-ID:
<A77B33D816BA6B4DB6BDA65A08DF8B990313E607 at exchsvr2.npl.ad.local>
Content-Type: text/plain;charset="us-ascii"

Dear all,

There are some reports on the presence of short-lived Cl-38, which
may indicate that nuclear chain reactions continue after shut-down:

http://japanfocus.org/-Arjun-Makhijani/3509 

http://blogs.nature.com/news/thegreatbeyond/2011/04/fukushima_update_did_nuclear_c.html


Kind regards,

Arvic Harms

Dr Arvic Harms
Radioactivity Group
National Physical Laboratory

 
 
Best Regards

Derek Putley

Technical Area Lead (Criticality) 
 
Serco (Technical Services)
Thomson House, Risley, Warrington, Cheshire, WA3 6GA, UK



*****Disclaimer************
This email and any attachments may contain confidential and/or 
privileged material; it is for the intended addressee(s) only. If 
you are not a named addressee, you must not use, retain or 
disclose such information.

Serco cannot guarantee that the email or any attachments are free 
from viruses.
The views expressed in this email are those of the originator and 
do not necessarily represent the views of Serco.

Nothing in this email shall bind Serco in any contract or 
obligation.

Please note that all email messages sent to Serco are subject to 
monitoring / interception for lawful business purposes.

Serco Group plc.  Registered in England and Wales.  No: 2048608 
Registered Office:  Serco House, 16 Bartley Wood Business Park, 
Bartley Way, Hook, Hampshire, RG27 9UY, United Kingdom.
*****End Disclaimer********