Replacing LNT with SNT

This post requires considerable background. If you are new to Gordian Knot News, you will probably want to read LNT is Nonsense and possibly The Case for 2 mSv/day before proceeding further.

Figure 1. This complex chemistry is keeping you alive. DNA repair takes place in a series of steps, requiring 25 minutes to about 12 hours depending on the damage. LNT ignores/denies this fundamental biology.

The Gordian Knot Group has posted an important paper, Replacing LNT with SNT, at the gordianknotbook.com web site. This paper was originally a submittal to the Health Physics Journal; but the publisher's terms were unacceptable, so it was withdrawn, prior to peer review. Attempts to post the paper to arXiv have been stymied by the lack of a qualified endorser.

The paper is too long and has far too many equations for a substack post. But the techies/radiation professionals/regulators in the choir should check it out. I believe the paper is the most complete argument yet for dumping LNT and replacing it with a repair sensitive, radiation harm model. (False modesty is not one of my many vices.)

The argument against LNT is simple and conclusive. LNT cannot replicate both the increased cancer incidence we clearly see when a large dose is received over a very short period and the lack of detectable increase when the same or much larger doses are acquired over far longer periods.¹ Any model that cannot do that must be rejected.

This means we must have a replacement. That replacement harm model must be well defined. Unless you can program your harm model, you do not have a model. No qualitative handwaving about unspecified thresholds and hormesis need apply.² The replacement must allow one to compute the harm (eg Lost Life Expectancy) associated with a given plume and population distribution. LNT can do that. The replacement must as well.

At the same time, the replacement must recognize our ability to repair radiation damage, and the fact that repair takes time. LNT cannot do this. Einstein once said ``as simple as possible, but no simpler". The Sigmoid No Threshold Model (SNT) is about as simple as you can get and still replicate both the clear harm inflicted by a dose rate spike and the lack of detectable harm from the same dose spread over a long period.

This paper firms up the basis for SNT, and applies that model to both the Fukushima and Chernobyl releases. To demonstrate compliance with the must-be-programmable criteria, the paper contains a python script for converting a dose rate profile to Lost Life Expectancy via SNT. This can be combined with plume data and the ethical assumption that all life years should be valued equally to compute the total Lost Life Expectancy associated with a release. This in turn can be the basis for a compensation scheme, based on each individual's dose rate profile. Without such a fixed compensation program, I doubt nuclear power will ever be able to live up to its promethean promise.

1. In some cases, LNT is off by more than a factor of 100.

2. Hormesis holds that small, properly timed doses of radiation can be beneficial, in much the same way as vaccines.