Attachment I SOW.doc

STATEMENT OF WORK

DESIGN AND FABRICATE FILTER AND STRAINER ELEMENTS

(SHAPED LIKE FUEL ELEMENTS)

March 19, 2021

1. Background

The National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) owns and operates a Test Reactor. This reactor is known by and licensed under the initialism NBSR, which stands for the National Bureau of Standards (NBS) Reactor. The NBSR is located on the NIST campus in Gaithersburg, Maryland, USA. The NBSR is heavy water (D2O) moderated and cooled, enriched fuel, tank-type reactor designed to operate at a thermal power level of 20 MW. The core is immersed in heavy water to thermalize fast neutrons to sustain the nuclear chain reaction, remove heat created by the reaction and serve as the first stage of shielding. The D2O inventory is contained in an enclosed process system that is blanketed by high purity helium gas to insulate the D2O from environmental air. The core is in the lower section of an aluminum tank. The reactor core consists of 30 fuel elements. The fuel elements are held and latched in place between the upper and lower grid plates.

All construction materials used in the reactor tank are either aluminum or stainless steel, with stainless steel present in only a few components. Aluminum and stainless steel are chemically compatible with the heavy water coolant and exhibit excellent resistance to corrosion and erosion. Aluminum has low induced radioactivity and is resistant to radiation damage.

The D2O has recently become contaminated with radioactive debris due to an event that was reported to the Nuclear Regulatory Commission (event number 55120). The amount and size of the particles are not confirmed. From camera images the particles seem to range from dust debris up to ¼” diameter.

Purpose

The purpose of this requirement is to procure 30 filter elements that are shaped like a fuel element. These elements will replace the fuel elements in the reactor core and be used to collect debris. Reactor Engineering has 1 mock filter element. No documentation exists for this mock filter element and thus it can only be used for reference.

2. Attachments

2.1 Pictures of Mock Filter Element:

2.1.1 Engineer with mock filter element

2.1.2 Removed nozzle

2.1.3 End view of nozzle

2.1.4 Filter side of nozzle

2.1.5 Cloth filter being removed

2.1.6 Engineer holding cloth filter

2.1.7 Transfer head

2.2 Drawings:

3.2.1 E-04-016 (8 sheets) Rev 5 (NBSR Fuel Element)

3.2.2 E37-001 (1 of 2) Rev 0 (Lower Grid Plate)

3.2.3 E37-002 (2 of 5) Rev A (Upper Grid Plate)

2.3 3D Rendering of Reactor Internal Structures

3. Requirements (BASE)

3.1 The Contractor must provide all labor, materials and equipment to select, design, fabricate and delivery to NIST thirty (30) filter elements shaped like NBSR fuel elements (circular cross-section is acceptable).

3.2 Calculate Cv_fuel for one fuel element (based on fuel element design). May use Crane Handbook or equivalent.

3.3 Design filter element (reference mock filter element photographs) and determine Cv_filter of a full length filter element:

3.3.1 Filter shall be a full (fuel-element) length stainless-steel mesh filter, mesh size 20 microns

3.3.2 Match the pressure drop across a filter assembly to the pressure drop across a fuel element by proposing an alternate pump line-up. Possibilities are provided in the following table. The normal flow with fuel installed is 9010 GPM, provided by 3 pumps running.

3.3.3 All materials used must not be detrimental to the D2O inventory or reactor internal structures. Material selection must be approved by the government's technical representative. Examples of acceptable material choices are aluminum, stainless steel and titanium.

3.3.4 Filter assemblies shall be equipped with a swing check valve (“trap door”) near the bottom that catches large debris when the flow stops. Check valve must be not particularly tight so that water leaks out of the filter element when it is removed.

3.3.5 Minimize fasteners used and design to reduce risk of fasteners becoming loose and falling into reactor vessel. All fasteners and connections must be approved by the government's technical representative.

3.3.6 Filter elements must be equivalent to fuel elements regarding fitting and latching into the upper and lower reactor grid plates. Note: Acceptance testing includes checking critical dimensions and installing and successfully inserting and operating each filter element in the fuel transfer training station.

3.3.7 Each filter element must be engraved with a number (1 through 30). Engraving must be like that of a fuel element and be identifiable under 10 feet of water.

4. Requirements (OPTION 1)

4.1 The Contractor must provide all labor, materials and equipment to select, design, fabricate and delivery to NIST thirty (30) strainer elements shaped like NBSR fuel elements (circular cross-section is acceptable).

4.2 Design strainer element such that Cv_strainer is significantly greater than Cv_fuel (see Requirements (BASE)):

4.2.1 Strainer shall be a full (fuel-element) length stainless-steel mesh (or perforated inner tube). Mesh corresponds to particle passing size of 0.040”.

4.2.2 Cv_strainer shall be larger than Cv_fuel, so the pressure drop across the strainer will be less than across a fuel element. Strainers will be run at approximately 10000 GPM, either because their Cv’s allow that to happen with three pumps, or a fourth pump will be deployed.

4.2.3 Strainer flow output will be re-directed horizontally to avoid spraying the underside of the top shielding plug of the reactor.

4.2.4 All materials used must not be detrimental to the D2O inventory or reactor internal structures. Material selection must be approved by the government's technical representative. Examples of acceptable material choices are aluminum, stainless steel and titanium.

4.2.5 Strainer assemblies shall be equipped with a series of staggered chevrons below the strainer entrance (within the envelope of the fuel element design), so that when the pumps are stopped, any debris that is not captured by the strainer (which is expected most of such debris) will be captured when it drops. There are larger particles than in the case of the use of the filters and therefore fall much faster. It is assumed that a “trap door” will not work in this case (like in the filter). Chevrons will have strategically placed drainage so that the element empties, also behind the staggered chevrons.

4.2.6 Minimize fasteners used and design to reduce risk of fasteners becoming loose and falling into reactor vessel. All fasteners and connections must be approved by the government's technical representative.

4.2.7 Filter elements must be equivalent to fuel elements regarding fitting and latching into the upper and lower reactor grid plates. Note: Acceptance testing includes checking critical dimensions and installing and successfully inserting and operating each filter element in the fuel transfer training station.

4.2.8 Each filter element must be engraved with a number (S01 through S30). Engraving must be like that of a fuel element and be identifiable under 10 feet of water.

5. Deliverables (BASE)

5.1.1 Conceptual design documents and drawings (*.pdf format) includes a draft schedule. Schedule due with bid for project.

5.1.2 Kickoff meeting. No later than 1 week after award of contract. This should be a virtual meeting setup by the contractor. NIST prefers using Microsoft Teams.

5.1.3 Preliminary design documents and drawings (*.pdf format). Due no later than 3 weeks after award of contract.

5.1.4 Final design documents and drawings (*.pdf format) due no later than 6 weeks after award of contract.

5.1.5 Note: conceptual through final design steps must be presented to the government’s technical representative. The contractor may proceed to the next step after the previous step has been reviewed and approved by the government's technical representative. Review to last no longer than 5 business days.

5.1.6 Conduct weekly status and planning meetings (kickoff meeting being the first one) from award of contract to completion of the contract. These should be virtual meetings setup by the contractor. NIST prefers using Microsoft Teams. Contractor must send written summaries (*.pdf format) after each meeting to NIST for review and concurrence. Meeting schedule may be modified as necessary by mutual agreement between the contractor and the government’s technical representative.

5.1.7 Thirty (30) filter elements shaped like NBSR fuel elements (mostly cylindrical cross-section is acceptable. Due no later than 12 weeks after award of contract.

5.1.8 Two (2) hard copies of all final documentation (calculations, reports, drawings and final schedule) and user manual. User-manual must include (at a minimum) operation, maintenance, bill of materials, list of recommended spare parts and troubleshooting instructions. Due no later than 14 weeks after award of contract.

5.1.9 All final design documents and user-manual (*.pdf format). Due no later than 14 weeks after award of contract.

6. Deliverables (OPTION 1)

6.1.1 Conceptual design documents and drawings (*.pdf format) includes a draft schedule. Schedule (based on Date of Option Award) due with bid for project.

6.1.2 Kickoff meeting. No later than 1 week after Option Award. This should be a virtual meeting setup by the contractor. NIST prefers using Microsoft Teams.

6.1.3 Preliminary design documents and drawings (*.pdf format). Due no later than 3 weeks after Option Award.

6.1.4 Final design documents and drawings (*.pdf format) due no later than 6 weeks after Option Award.

6.1.5 Note: conceptual through final design steps must be presented to the government’s technical representative. The contractor may proceed to the next step after the previous step has been reviewed and approved by the government's technical representative. Review to last no longer than 5 business days.

6.1.6 Conduct weekly status and planning meetings (kickoff meeting being the first one) from award of contract to completion of the contract. These should be virtual meetings setup by the contractor. NIST prefers using Microsoft Teams. Contractor must send written summaries (*.pdf format) after each meeting to NIST for review and concurrence. Meeting schedule may be modified as necessary by mutual agreement between the contractor and the government’s technical representative.

6.1.7 Thirty (30) strainer elements shaped like NBSR fuel elements (mostly cylindrical cross-section is acceptable. Due no later than 12 weeks after Option Award.

6.1.8 Two (2) hard copies of all final documentation (calculations, reports, drawings and final schedule) and user manual. User-manual must include (at a minimum) operation, maintenance, bill of materials, list of recommended spare parts and troubleshooting instructions. Due no later than 14 weeks after Option Award.

6.1.9 All final design documents and user-manual (*.pdf format). Due no later than 14 weeks after Option Award.

7. Government Responsibilities

7.1 Provide pictures, drawings, and information pertinent to completing task.

7.2 Review and approve of conceptual, preliminary and final design.

7.3 Inspect thirty (30) filter/strainer elements upon delivery to NIST. Inspections incudes checking critical dimensions.

7.4 Supply and install a fuel transfer head on each filter element (at NIST).

7.5 Install and operate each filter element in the fuel transfer training station (at NIST).

7.6 Install and operate the filters and strainers in the NIST Reactor at the Government’s sole risk and discretion.

8. Periods of Performance

The period of performance for the BASE plus OPTION is 1 year after Contract Award. Both the BASE and OPTION have specific requirements as to the meaning of timely delivery as stipulated in this Statement of Work.

9. Place of Delivery FOB NIST Gaithersburg