WO1995013617A1

WO1995013617A1 - Radioattenuant composition, method and container

Info

Publication number: WO1995013617A1
Application number: PCT/US1993/010835
Authority: WO
Inventors: Karl T. Blaufuss
Original assignee: American Intercontinental Investment Corporation
Priority date: 1993-11-10
Filing date: 1993-11-10
Publication date: 1995-05-18
Also published as: AU5983094A

Abstract

A radioattenuant composition comprising halite of various particle sizes ranging from fines to rock size which are bound together with a binder such as, for example, a resin system so as to be able to form the material into a radioactive containment vessel of relatively low cost and low weight.

Description

RADIOATTENUANT COMPOSITION, METHOD AND CONTAINER

TECHNICAL FIELD

The invention relates to a relatively low cost, low weight, easily handled radioattenuant composition which is easily prepared and which is readily oldable into containers or components thereof within which may be contained radioactive materials which emit radioactivity. More specifically, the invention relates to a halite or salt mixture of selected density and bound with a binding agent which is nonreactive or inert to the halite or salt, and which is not water soluble.

The unique mixing of materials making up the radioattenuant composition and the formation into, for example, formed containers, provides a relatively low weight, low cost means of shielding an ambient environment from radioactivity, such as gamma and x-ray emissions. BACKGROUND ART

It has long been known that governments of the world have utilized naturally formed geological formations within which to store radioactive material. One typical geological structure which has been used for many years are salt domes or the like wherein radioactive wastes have been stored in the geological structures as a readily available, economically low cost, permanent storage facility wherein the radioactive material may decay over hundreds and even thousands of years.

However, as far as is known, no one has suggested the utilization of salts by themselves, from fines to coarser rock size components, to be bound together with a binding agent such as resin or the like, and wherein a relatively low cost, low weight container is fabricated to attenuate radioactivity of less hazardous radioactive material, for example, such as medical wastes or the like. As delimiting examples of suitable radioactive materials to which this invention is directed are Iridium-192 and Cobalt-60, examples of materials whose radiation is greatly attenuated by the compositions and containers of the disclosed invention. DISCLOSURE OF THE INVENTION

The invention pertains to a radioattenuant composition, the method of forming the composition, and the use of a container for storing radioactive materials wherein the containers are easily handled and transported to or from disposal sites, or used as permanent containers at a disposal site location.

In its simplest form, salt of various sizes such as fines, granulated and rock-size is mixed with a binding agent wherein the binding agent renders the mixture relatively waterproof, and wherein it is inert to the materials which it will bind together.

More specifically, the various forms of salt, from fines size to rock size, are continuously mixed with a binding agent such as a catalyst-activated resin system to a selected crtimum ratio of salt to binding agent, to obtain the highest density of combined material which composition is thereafter formed into slabs, panels, or containers for use in the attenuation of emitted gamma and x-ray emissions from radioactive material.

In its simplest form, the radioattenuant composition comprises a combination of:

3 - 6 wt/% fine salt

20 - 40 wt/% granulated salt 50 - 70 wt/% rock salt; and

4 - 8 wt/% binder

In the method of forming the radioattenuant composition, one selects component materials of various configurations ranging from fines to rock size, and wherein these component materials are simultaneously mixed while introducing the binding agent, and thereafter, thoroughly mixing the component materials with the binding agent and forming containers or components thereof, and through compaction obtaining as high a density as possible, and allowing the formed and mixed component materials and binding agent to solidify into a container or component thereof. The container or component thereof formed of salt and binder, ideally has an exterior surface that is moisture resistant and inert to the salt which it binds into the formed shape. An example of the prior mixing art in this regard is Jeppsen, Building Material and Method for Making Same, U.S. Patent 4,021,401, issued May 3, 1977; and Jeppsen, Machine for Mixing Aggregate and Resin, U.S. Patent 4,004,782, issued January 28, 1977.

Ideally, what is contemplated by the invention is a low- cost, easily asportable container of hexagonal shape, made of the formed composition, and having an internal volume into which radioactive material may be stored, and wherein a cover seals the container, and wherein the exterior of the container may have an encapsulating sheath of material such as aluminum or the like to provide structural integrity to the formed container and to resist external damage to the container, as well as to resist ambient moisture that may tend to disintegrate the radioattenuant composition, if damaged. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram illustrating the mode of combining the components of the radioattenuant composition of the invention;

Figure 2 is a diagram illustrating the method of determining optimum density of the formed composition;

Figure 3 is a perspective view of a formed container of the invention; and

Figure 4 is a view taken along the line 4-4 of Figure 3. BEST MODE FOR CARRYING OUT THE INVENTION

Material Selection

Salt Component

The halite component of the composition consists of a blend of various particle sizes from the smallest fines passing a No. 270 US standard sieve (270 openings per inch) to large particles up to 3/4" in size. In selecting the halite, the components are commercially obtainable as rock salt, granulated salt and powdered salt, with each component being size graded. The gradings are calculated to produce a combined gradation as close as possible to a straight line on a graph having the vertical (y) axis the percentage of material passing through the sieve, and the horizontal (x) axis the 0.45 power of the sieve opening in inches. A straight line on this chart yields the most dense gradation, as those of ordinary skill in the art will recognize.

A summary of the average gradation values for the halite components of the composition appears in Table A.

TABLE A

DESIGNED COMBINED GRADATIONS FOR HALITE

Average gradation values for various components

Table shows Percent Passing bv Weight

U.S. Standard Sieve Size

Component

Component % 3/4" 1/2" 3/8" #4 #8 #16 #30 #50 #100 #200 #27

Powdered Salt 4 100 100 100 100 100 100 99 97 91 34 17.

Granulated Salt 31 100 100 100 100 100 69 36 20 10 3.5

Lump Salt 65 100 82 58 20 0.4 0.3 σi Total 100

Combined Grading 100 88 73 48 35 26 15 10 7 2

Coarse Limit 100 76 68 46 33 21 14 8 6 0

Fine Limit 100 88 77 54 41 29 21 14 10 5

6

Binder

The binding agent should be one that is inert to the halite materials which it is expected to bind, and one which is non-soluble in water. While those of ordinary skill in the art will recognize various binding agents that would fulfill the requirements of the invention, it has been found that resinous binder compositions, as found in the foundry molding art, may be utilized. See U.S. Patent 4,021,401, id. In the foundry molding art, where molds are made of sand, the sand is held together by a binder which is usually introduced into the sand during a mixing operation as a resin binder composed of generally three components: a binder, a resin, and a catalyst. However, while the binders used in the instant invention may be any one of those used in the foundry molding art, the manner of introduction is dissimilar as will become apparent. The term binder as used in this application is intended to include the totality of components such as binder, resin, and catalyst as found in the foundry molding art, as well as individual components performing a binding function.

The binder component may be either a phenolic resin, epoxy resin or a furan resin, and indeed those of ordinary skill in the art will recognize other binder compositions, all of which are intended to be covered by the invention disclosed herein.

In the case of a phenolic resin binder composition, for example, the resin component is an organic solvent solution of non-aqueous phenolic resin. The binder or hardener component is a liquid polyisocyanate having at least two isocyanate groups per molecule. The catalyst is a tertiary amine. A full description of the chemical contents and properties of the phenolic resin binder composition may be found in U.S. Patent No. 3,409,579 or U.S. Patent No. 3,676,392. An example of a furan resin binder composition is disclosed in Canadian Patent No. 934,492.

Additionally, epoxy resins may be utilized, the only requirement being that the resin or binder system be polymerizable, both to prevent reaction with other chemicals and oxygen, and to resist dissolution in water.

The resin is usually added in an amount of about 4%-7% by weight of the rock salt component, with the resin content varying with the surface area of the rock salt to be covered. It should be recognized that the binder is mixed with the components making up the overall composition, i.e., sized and graded salt including fines, to produce a low-porosity blend of binder and salt, with the working time being controlled by both the catalyst additions (where the binder requires) and by the temperature of the components going into the overall composition. Preliminary Steps to Composition Formation

The individual components making up the halite component are not premixed, because to do so causes segregation of particles by size or a settling out of the fines and the like, so as to create difficulties in blending. Thus, it is preferred to have each of the graded materials available for individual addition into the mixture, as will be described, to obtain a homegenous mixture.

However, prior to production mixing of the halite components and the addition of the binder, it will be necessary to prepare trial mixtures using varying binder or resin additions (as a percentage by weight) and plot the unit weight (determined under compaction methods identical to the methods proposed for production, i.e., air tamper or manual) against the resin or binder content to define the peak or maximum density of the combined material. The resin or binder content at that peak density is the desired resin or binder addition quantity for that halite or salt gradation.

A slight excess amount of binder or resin, 0.1-0.2 %/wt, will cause the composition mass to liquify under compaction to full density and to close any porosity, thereby eliminating air voids so that the final material is a well-blended mixture of densely graded halite with the porosity voids filled with resin or binder. The Mixing and Formation Process

Once the composition of the halite components have been determined as indicated above, and the optimum resin or binder content has been determined, as outlined above and as shown in Figure 2 in graphic form, and in referring to Figure 1, it will be seen that the halite components are simultaneously added to a continuous mixer, and after initial blending of the introduced materials, a binder or, in this particular case the components of a resin system, are introduced into the mixer as separate components. Continued mixing coats each particle with the resin components and the catalyst.

After thorough mixing and before any setting takes place, the mixture is transferred to a mold or form, and the resulting plastic mass is compacted as with a tamper or vibrator, so as to exclude any entrapped air. The composition is compacted into a form such as a panel which may be used to form a container, or into a container form itself.

Referring to Figures 3 and 4, a hexagonally shaped container is illustrated which has a metal skin made of ductile iron or aluminum, for example (plastic wrap would also suffice in some applications) and the plastic composition poured into the form to define a chamber.

More specifically, referring to Figures 3 and 4, it will be seen that the container 10, in this particular instance, has an aluminum shell 12 into which the compacted composition 14, comprising the graded halite and binder or resin material is poured, to form the hexagonally shaped-container 10.

The hexagonally-shaped container 10 has a stepped cover 16, stepped for radiation entrapment, and forms between it and the body of container 10 a space storage volume 20 within which may be received the radioactive mass (not shown) whose radiation is to be attenuated.

In the specific depiction of container 10, as illustrated in Figures 3 and 4, the container 10 is about the size of a 55-gallon drum so that it is easily handled and transported. Testing and Conclusions

The radio attenuation properties of material are typically reported as tenth value layer (TVL) and half value layer (HVL) thickness, and these thickness values vary with the gamma force energy or x-ray source energy.

The thickness of a material that will reduce the amount of radiation to one-half is called a half value layer (HVL) . The thickness of a material that will reduce the amount of radiation to one-tenth (90% reduction) is called the tenth value layer (TVL) .

Using lead to shield both Cobalt 60 and Iridium 192 as sources, the following table gives the TVL and HVL thicknesses for any source activity level. TABLE B

Source Lead

TVL HVL

Co 60 1.6 " 0.49" Ir 192 0.79" 0.24"

In order to determine the efficacy of the formed material, in accordance with the teachings of the instant invention, the TVL thickness for the composition used in the hereinafter described tests and calculated TVL thickness for other commonly used radioattenuant materials were determined. These values were determined for both Cobalt 60 and Iridium 192 sources.

The following table accurately depicts the radioattenuant properties for the indicated materials:

TABLE C

TVL Thickness in Inches for Various Materials

Material Cobalt 60 Iridium 192

Depleted Uranium 0.87 0.40

Tungsten 1.05 0.54

Lead 1.6 0.79

Iron 2.6 1.6

Heavy Concrete* 3.5 2.2

Halite Composition of 10.2 8.0 Invention

Note* The value for heavy concrete was computed for concrete containing steel punchings and steel shot as aggregate, and weighing 362#/cubic foot. 1 cubic yard of this concrete contains 658# Portland cement, 208# water, 504# sand, and 8,400# of steel aggregate. 1 cubic foot of the concrete contains 311# of steel. To put the efficacy of the instant invention in proper perspective, there has been estimated a material cost for one square foot of 1 TVL to shield Cobalt 60 for various materials, and the following tabulation depicts the same:

TABLE D

Estimated Cost Per Wt Of

Material Thickness Pound 1 sσ ft Cost ( $ )

Depleted 0.87" $ 40.00 84.0# 3,360.00 Uranium

Tungsten 1.05" 50.00 97.0# 4,850.00

Lead 1.6 " 1.00 94.0# 94.00

Iron 2.6 " .30 105.6# 31.68

Heavy Concrete 3.5 " .25 105.6# 26.40

Halite 10.2 " .118 88.4# 10.43

Composition of

Invention

There are, however, problems associated with the use of several of the materials illustrated in Table D. Depleted Uranium and Sintered Tungsten are too expensive for large attenuators.

Tungsten is not fabricated into thicknesses greater than two inches (2") because of the extreme pressures combined with high temperatures for required sintering. Depleted Uranium is radioactive, and out-gasses Radon and daughter products of Radon. Possession of large quantities of Uranium requires both special licenses and special handling and storage procedures.

Lead is no longer the shield of choice because of low melting point (621°F) . Lead has low rigidity for large areas. Lead is usually attached to a steel backing plate to facilitate construction.

Iron (steel) becomes radioactive when bombarded by neutrons, causing the shield to become radioactive.

Heavy concrete has several problems:

(1) Void spaces and shrinkage cracks within the mass cause unpredictable and sometimes dangerous leaks of radiation.

(2) The material is very hard to handle, and labor costs for construction are significantly higher than for the halite composition of this invention.

(3) Long-term, high-temperature exposure damages concrete paste.

(4) Metallic aggregates become radioactive when radiated with neutrons.

However, the halite composition of the instant invention, confined within a containment structure, does not change gamma radioattenuant properties, even if heated hot enough to destroy the agglomerating matrix. The agglomeration system will fail above 450°F, but the radioattenuant will remain intact. The material will not melt until temperatures in excess of 1400°F are experienced.

There were formulated several containment vessels using the methods and composition of the instant invention. The following examples illustrate the practice of the invention:

A containment vessel, in order to test the radioattenuation character of the instant composition, was formulated using the following:

Example A Rock Salt (+#4) 65% by weight of salt of total mass of composition

Granulated Salt 31% by weight of salt of total (Table salt size) mass of composition

Powdered Salt 4% by weight of salt of total (Finely divided) mass of composition

Binder 7.0% added by weight to salt

Example B

Rock Salt (+#4) 65% by weight of salt of total mass of composition

Binder 7.5% added by weight to salt Using the individual components for the halite component identified in Examples A and B, above, the materials were weighed out and thoroughly blended in the proportions indicated to produce the desired volume of mixed material. The blended salt and the resin binder system were thoroughly mixed in a continuous flow mixer, with the binder resin and catalyst system continuously injected into the mixture. After mixing, the mixture was fabricated into two each 8" diameter x 8" high right circular cylindrical test units, using 7.5% total resin content for Example A and into a model containment using 7.0% total resin content for Example B.

The containment vessels were made of 3/32" roll-formed aluminum sheet with a 3/32" aluminum bottom, heliarc welded to produce an open-topped cylindrical vessel 47" outside diameter by 48" high. A central void was provided using 4" polyvinyl chloride plastic pipe, which extended to 21" clear of the bottom of the vessel. The void was provided for testing purposes to allow a radioactive source to be placed in the middle of the containment vessel.

Radiation Attenuation

Gamma radiation from the disintegration of various nuclide materials is generated at differing energy levels depending upon the material undergoing decay. The higher the energy (measured in electron-volts) , the less probability that the radiation will penetrate a thickness of a substance before being scattered or absorbed. A radioattenuator is a substance used to absorb or scatter the gamma radiation. The most familiar radioattenuators are lead, heavyweight concrete, and spent uranium. These substances are very effective, but are all very heavy and expensive. Lead is not especially desirable because of its low melting point.

If the isotope to be contained during its decay is known, then the energy of the gamma radiation is known, and a radio- attenuator can be designed to either absorb or scatter almost all (99.7% certainty) of the gamma radiation, or to reduce the radiation levels to acceptable levels, even if it is theoretically impractical to absorb or scatter 100% of the same radiation. The attenuator shield is designed for both the total energy radiated and for the particle energy.

Each radioactive isotope produces gamma radiation of a specific energy level, so that a shield for a Cobalt-60 source (which radiates gamma particles with energies of 1.173 and 1.332 million electron Volts or Mev) will be both thicker and heavier than a shield for Beryllium-7 (which radiates gamma particles with energies of 0.477 Mev), presuming that both sources contain the same Curie radioactivity.

A Curie (Ci) is the unit rate of radioactive decay, and is the quantity of radioactive nuclide which undergoes 3.7 x 10¹⁰ disintegrations per second (37,000,000,000 disintegrations per second) . The theoretical free-air radioactivity counts at any distance are based on the following formula:

Free air count, N = K Ci 420 counts/min/1 mR/hour at one foot from the source.

Where K = 14.5 R/hour/Curie at l¹ for Co-60 or K = 5.2 R/hour/Curie at l¹ for Ir-192

The number calculated is then adjusted as the inverse square of the distance from the source. For example, the quantity N is divided by 4 to obtain the theoretical free air count at 2' from the source, or by 9 to obtain the theoretical free air count at 3* from the source.

Using ratemeter counts under various test conditions, the attenuation characteristics of the halite compositions were measured and are detailed below.

The design methods are similar for the design of attenuators for electric x-ray tubes.

Test Protocol

Using the two exemplar attenuator cylinders described above, the amount of gamma radiation transmitted through the axis of the cylinders was measured by taking ratemeter readings in counts per minute at each test condition at various distances, using two different radionuclide sources. The measurements comprised:

(a) the background count,

(b) the full radiation count without attenuation, (c) the reduction of radiation count yielded by each attenuator, and

(d) the reduction of radiation count yielded by multiple attenuators.

Measurement of radiation is described in the American Society for Testing and Materials (ASTM) Standard Practice for the Measurement of Radioactivity, D-3648.

The test sources used were:

(a) 21.5 Curie Cobalt-60 source, Gam atron 50A SN 50-54, Source Model Number A-7-A, Source Serial Number 2069

(b) 19.5 Curie Iridium-192, Industrial Nuclear Source Model Number 88, Source Serial Number 2589.

Radiation was measured using a remote sensing Geiger counter, made by NDS Products, Model ND-500P, Serial No. 11450, calibrated 8-28-92. The detector is saturated at radiation levels greater than 15 R/hr (15,000 mR/hr) .

With the sources locked into the transport containers located well away from the detector, background counts were made. The source was located a measured distance from the detector. This distance was calculated to produce a free-air count of 200,000 counts per minute, then checked by exposing the source. Small adjustments were made to bring the free-air count to a metered 200,000 counts per minute.

Attenuator cylinder A of Example A was placed in the source-detector path, and the source was extended into the columnator used for directing radiation. The attenuated counts were taken and the source was cranked back into the storage container.

Attenuator cylinder B of Example B was placed in the source-detector path, and the source was extended into the columnator used for directing radiation. The attenuated counts were taken and the source was cranked back into the storage container.

Both attenuator cylinders A and B were placed in the source-detector path, and the source was extended into the columnator. The attenuated counts were taken, and the source was cranked back into the storage container.

This evaluation sequence was performed using both the Iridium and Cobalt sources.

After completion of the test, the attenuator blocks were checked for residual radioactivity.

TEST RESULTS

Source Co-60 Ir-192

Activity 21.5 Ci 19.5 Ci

Source-detector distance, feet* 25.5 16.5

Background, counts/minute 0/10 0/10

Full power counts/minute 200,000 200,000

Attenuated by cyl A, counts/min 70,000 51,000 thickness, inches (at center) 8.00 8.00 Attenuated by cyl B, counts/min 72,000 53,000 thickness, inches (at center) 8.00 8.00

Attenuated by cyls A and B, counts/minute 23,000 25,000

Radiation survey of blocks 0/10 0/10 after test, counts/minute

* to produce 200,000 counts per minute in free air

The radioactive sources were placed into the well of the containment vessel and transmitted gamma radiation readings were taken at the compass points around the vessel. These data are detailed below.

Source Co-60 Ir-192

Activity 19.5 Ci 25.0 Ci

Gamma radiation

North side, cts/min 124,000 71,000

West side 123,000 80,000

South side 114,000 122,000

East side 120,000 93,000

Average, counts per minute 120,300 91,500

Calculated free-air count at 24", counts/minute 32,733,750 13,650,000

The cobalt source was placed 1-1/2" from the vessel and the gamma radiation was measured through the entire thickness of the vessel. The path length from source to detector was

49-1/2", and the calculated free-air count at that distance was 7,873,720 counts per minute. The attenuated reading through the vessel was 4,000 counts per minute, for a 99.95% attenuation. The cylinder dimensions and weight are tabulated below:

Cylinder A Cylinder B

Weight: 11,284 gms 10,760 gms

Dimensions: 8" dia x 8 " 8" dia x 8"

Calculated Average

Density 106.9 #/cu ft 101.9 #/cu ft

Calculated Specific

Gravity 1.713 1.633

After-test radiation check 0/10 ct/ in 0/10 ct/min

The background levels prior to the test ranged from 0 to 10 counts per minute.

It is found from the test results that the halite and binder composition attenuated the emitted radiation.

It is found that the method of making the radioattenuant composition, the composition itself and being formed in the container, provides a means of safely storing radioactive masses, providing the same are not so large in Curie activity as to generate an undue amount of heat. Furthermore, the containers of the invention provide an easily asportable radioactive containment vessel at a manageable weight, and at an economical price.

While the invention has been described with respect to specific examples and illustrations, those of ordinary skill in the art will, of course, recognize that other modifications and changes are indeed possible, all in keeping with the tenor of the invention, and all such changes and modifications will present themselves to those of ordinary skill in the art and are intended to be covered by the appendant claims.

Claims

1. The method of forming a radiation attenuation container or component thereof comprising the steps of: a) selecting component materials of various configurations ranging from fines to rock size; b) simultaneously mixing said component materials while introducing a binding agent; c) thoroughly mixing said component materials with said binding agent; d) forming a container or component thereof to form a storage space for receiving a radioactive material with said component materials and binding agent; and e) allowing said formed component materials and binding agent to solidify.

2. The method in accordance with Claim 1 wherein said component material comprises halite.

3. The method in accordance with Claim 2 wherein said binding agent comprises a resin inert to said component materials.

4. The method in accordance with Claim 3 wherein said binding agent is non-soluble in water.

5. The method in accordance with Claim 4 including the step of determining the maximum relative density of said component materials to the amount of binder.

6. The method in accordance with Claim 5 including the step of tamping said component materials and binding agent during step d) .

7. The method in accordance with Claim 6 wherein said component materials comprise about:

3 to 6 wt/% of the formed composition of fines;

20 to 40 wt/% of the formed composition of granulated;

50 to 70 wt/% of the formed composition of rock- size.

8. The method of attenuating radioactive emissions comprising storing a radioactive substance in a container composed of a bound material comprising: about 3 to 6 wt/% of fine salt; about 20 to 40 wt/% of granulated salt; about 50 to 70 wt/% of rock salt;

9. The method in accordance with Claim 8 wherein said container is hexagonally shaped.

10. The method in accordance with Claim 9 wherein said container has an exterior surface inert to the ambient environment in which it is to be stored.

11. A container for storing low level radioactive material comprising a composite material formed of salt and binder, and having an open top and integrated walls forming an internal volume adapted to receive said radioactive material, the wall thickness of said container being selected to attenuate a selected level of emitted radiation and a cover of said composite material to cover said top and surround said radioactive material encased in said internal volume to contain the same in radiation attenuation fashion.

12. The container in accordance with Claim 11 wherein said radioactive material is gamma ray emitting.

13. The container in accordance with Claim 12 wherein said composite material comprises about: about 3 to 6 wt/% of fine salt about 20 to 40 wt/% of granulated salt about 50 to 70 wt/% of rock salt

14. The container in accordance with Claim 13 wherein said composite material has a density within the range of about 90 to 115 pounds per cubic foot.

15. The container in accordance with Claim 14 wherein said binder is inert to the salt component of said composite mixture.

16. The container in accordance with Claim 15 wherein said container has an exterior surface impenetrable by water.

17. The container in accordance with Claim 16 wherein said container is hexagonally configured.

18. The container in accordance with Claim 17 wherein said container is about the size of a 55-gallon drum.

19. The container in accordance with Claim 18 wherein said binder is resin based, non-soluble in water, and is inert to said salt component.

20. The container in accordance with Claim 19 wherein the opening into said internal volume is stepped in the axial direction of said container.

21. A radioattenuant composition comprising a combination of:

3 to 6 wt/% fine salt

20 to 40 wt/% granulated salt 50 to 70 wt/% rock salt

4 to 8 wt/% binder

22. The composition in accordance with Claim 21 wherein said binder is a resin-catalyst activated system.

23. The composition in accordance with Claim 22 wherein said resin consists of a polyisocyanate binder component, a phenolic resin, and a tertiary amine.