Questions and Responses to RFQ 1333ND21QNB610152.pdf

Questions and Responses to Request for Quotation 1333ND21QNB610152

QUESTION:

Can NIST provide some reference measurements (to the 0.001”) of the existing filter, specifically:

• For the lower head adapter, what is the diameter of the machined section that goes into the lower core plate. Production drawings for the fuel assembly have this at 2.354” (Photo Filter Element 2).

• For the “upper head adapter” what are the out-to-out dimensions of the rectangular head that’s machined (Photo: Filter Element 7)

• For the “upper head adapter” what’s the thickness of the rectangle at its outer most corner?

(Photo: Filter Element 7)

RESPONSE:

In answering these questions, we must assume they are raised with the intent to provide functional filter elements without having to adhere to some of the very strict dimensional (and geometrical tolerancing) requirements that apply to a fuel element (which is what is specified in the RFP by our reference to the fuel element drawings).

We intend to (and will) make considerable concessions to these requirements because filters (and strainers) are not fuel elements.

For example:

1) The nozzle (DIA 2.354) of the fuel element (E-04-016 (4 of 8) Rev 5) has the same diameter along the entire cylindrical portion (2.5” CALCULATED LENGTH). For the filter (and strainer) it is sufficient if a small portion of the height of the cylindrical portion (say 0.5”) has that diameter.

This portion could be located immediately below the cone/cylinder transition. The remainder of the cylindrical portion can be cut to a much smaller diameter. The function of having at least some portion of the nozzle at 2.354” DIA is to prevent particulate matter from passing by the filter assembly. We could also reach this result by making the nozzle simply a lot shorter, however, we need to maintain the “mating length” of the nozzle approximately equal to the “mating length” of the fuel design (albeit in different form) to not impair the “fuel loading procedure”, which will be re-written for the filters and the strainers. In that procedure the nozzle “catches” first. To properly catch, the diameter at the point of catching does not matter, hence can be reduced substantially.

2) Likewise, for the upper assembly (E-04-016 (3 of 8) Rev 5) it will be sufficient if the projection of the (3.125 x 3.812)” square is only held at a fraction of the total height of the bar-shaped height (3.67” CALCULATED HEIGHT). Here too, 0.5” would suffice and is best located somewhere in between the lower countersunk holes and the (1.313 x 2.046)” windows and wrap all around the bar shape. In that case the true location of the countersinks must remain where they are with respect to the fuel element design or else the countersunk screws will interfere with the fuel element head assembly (they go too deep). It is sufficient if these screws remain below the projection (even if the projection is only 0.5” tall).

3) These two concessions would effectively eliminate all significant parallelism requirements between the nozzle axis and the intersections of the four faces of the Upper End Adapter, while still producing a fully functional filter/strainer.

4) The solutions given in this example are but one way to effectively loosen the geometric tolerance requirements for the filter assembly, while maintaining a workable filter design. We can think of several others.

5) The proposed design will be used to evaluate the understanding and technical ability demonstrated in the submission. We understand the conceptual design may change as the final design comes into focus.

6) We believe that these concessions are much more significant than what can be achieved by sharing dimensional information from parts that have never been put to the test (i.e. our filters) and for which no design information is available. Chances are that our filter elements are mostly very closely held to the original fuel design and thus provide not as much relief as may be desirable.

QUESTION:

Regarding the test stand/test station the government intends to use for validation of fuel element assembly:

• Are drawings of the test/training station available? Specifically, are the clearances/fits of the training/test stand the same as the reactor internals?

RESPONSE:

There are no drawings. Perhaps some sketches. Yet, the training station can double as a dimensional inspection device (a go/no-go gauge) for the relevant overall dimensions of the filter element. To the best of our knowledge it closely approximates the situation in the reactor.