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Comment on “ID: NRC-2015-0270-0002 List of Approved Spent Fuel Storage Casks: Holtec International HI-STORM 100 Cask System; Certificate of Compliance No. 1014, Amendment No. 10” here: https://www.regulations.gov/#!documentDetail;D=NRC-2015-0270-0002 by 13 April 2016, 11.59 PM, ET. This includes all day on the 13th, NY-DC (Eastern), minus one minute.

Over the course of now 16 years, Holtec has gotten 10 exemption “Amendments” on its Certificate of Compliance (CoC) for its Hi-Storm 100 spent NUCLEAR fuel cask system. Over the last couple of years, each amendment has had one revision, and there are multiple changes within each Amendment and revision. The tendency appears to be avoiding quality assurance and testing. The number of Holtec “exemptions” for the Holtec High Storm 100 can thus be estimated as in the 60 to 100 range.
Holtec Diablo casks Dec. 2006
Note the comparatively small size and poor location of the passive cooling vents (small holes at top and bottom).

This may sound well and good until one realizes that they are apparently trying to evade testing the air and heat distribution: “Amendment No. 10 revises Condition No. 9 of CoC No. 1014 to provide clearer direction on the measurement of air velocity and modeling of heat distribution through the storage system.https://www.regulations.gov/#!documentDetail;D=NRC-2015-0270-0002 Thus far, we only found this proposal by Holtec from last August: http://pbadupws.nrc.gov/docs/ML1524/ML15240A236.pdf It may be somewhere in the final documentation but as usual, the US NRC’s comment info violates “The Plain Writing Act of 2010 (Pub. L. 111-274) [which] requires Federal agencies to write documents in a clear, concise, well-organized manner that also follows other best practices appropriate to the subject or field and the intended audience“. If we run across it in the final documents we will add the info to the post. Since what Holtec wants, Holtec gets when dealing with the US NRC, or so it appears, we will assume this was the final decision. We have a vague memory, however, that the proposal was to measure only the bottom vents. Since heat rises, this would be appear a means of evading the truth. But, we’ve been unable to find that part. Rather, there is an apparently silly or sly idea of adding ducts to measure circulation.

As can be seen in the picture on top, below, and in Models here, http://www.nwtrb.gov/reports/eds_rpt.pdf, the venting is small and air circulation-cooling would be clearly poor.
Cask vents

This is what they are supposed to be doing:
Condition 9 (Special Requirements for First Systems in Place) of the Certificate of Compliance (CoC) for the Holtec HI-STORM 100 cask storage system states the following: The air mass flow rate through the cask system will be determined by direct measurements of air velocity in the overpack cooling passages for the first HI-STORM Cask Systems placed into service by any user with a heat load equal to or greater than 20 kW. In the aboveground HI-STORM Models (HI-STORM 100, 100S, etc.), the velocity will be measured in the annulus formed between the MPC shell and the overpack inner shell. In the underground HI-STORM Model (HI-STORM 100U), the velocity will be measured in the vertical downcomer air passage. An analysis shall be performed that demonstrates the measurements, and validates the analytic methods and thermal performance predicted by the licensing-basis thermal models in Chapter 4 of the FSAR.http://pbadupws.nrc.gov/docs/ML1524/ML15240A236.pdf This is clearly inadequate, anyway. The measurements need to be constantly done.

However, Holtec pretends that they cannot measure the air mass flow rate and proposes this crazy system of adding ductwork that would change the flow and temperature! “With respect to a revised approach, Holtec is proposing a test to be performed that measures the total air mass flow through the four (HI-STORM 100) or eight (HI-STORM FW) inlet ducts. As an example, this test can be performed by adding ductwork to the HI-STORM inlets, using a hot-wire anemometer to measure the air velocity inside those ducts.http://pbadupws.nrc.gov/docs/ML1522/ML15226A560.pdf (Entire letter at bottom of our post.)

More up to date ways exist for testing the air flow and temperature, but if they did not it would still be Holtec’s responsibility to invent one and not come up with the apparently brainless idea of adding ducts .

In 1935:
1935 Anemometry NIST US

Expert comment: “Hot wire anemometer is an old technology from the 19th century. There are new technologies that can measure flow precisely like Magnet meters, paddlewheels, resistive meters all of those are not direct non intrusive. Putting a wire in a flow is dumb and lazy is not accurate and has to be calibrated. It can be calibrated but certainly is not the right way to do it nowadays.

See frighteningly silly or sly Holtec letter from August below:
ML15240A236, August 2015 Holtec letter re testing vent
ML15240A236, Holtec August 2015 testing vents
Holtec 2015 Aug testing vents ML15240A236