SOURCES SOUGHT
R -- Technical Assistance for Improvement of the Accuracy of the Beta Dose Calculations in VARSKIN 3.1 Computer Code
- Notice Date
- 1/22/2010
- Notice Type
- Sources Sought
- NAICS
- 541690
— Other Scientific and Technical Consulting Services
- Contracting Office
- Nuclear Regulatory Commission, Office of Administration, Division of Contracts, 12300 Twinbrook Parkway, Rockville, Maryland, 20852-2738, United States
- ZIP Code
- 20852-2738
- Solicitation Number
- RS-RES-10-124
- Archive Date
- 2/16/2010
- Point of Contact
- Michael Mills, Phone: (301) 492-3621
- E-Mail Address
-
michael.mills@nrc.gov
(michael.mills@nrc.gov)
- Small Business Set-Aside
- N/A
- Description
- This is a “Sources Sought” synopsis. This is not a Request for Proposals. The NRC is seeking technical assistance for customizing the computer code VARSKIN 3 and NUREG/CR-6918. This notice supports a market survey and analysis to determine the range of available contractors and their utility and capability to assist the NRC with the prospective work described below. The NRC does not intend to award a contract on the basis of this request or compensate responders for their information. The purpose of this announcement is to provide potential sources the opportunity to submit information regarding their capabilities to perform work for the NRC free of Organizational Conflict of Interest (OCOI). For information on NRC OCOI regulations, visit NRC Acquisition Regulation Subpart 2009.5, entitled “Organizational Conflicts of Interest” (http://www.nrc.gov/about-nrc/contracting/48cfr-ch20.html). All interested parties, including all categories of small businesses (small businesses, small disadvantaged businesses, 8(a) firms, women-owned small businesses, service-disabled veteran-owned small businesses, and HUBZone small businesses) are invited to submit a response to the market research questions below and submit the capability information as described below. Submission of additional materials such as glossy brochures or videos is discouraged. Responses are due no later than February 1, 2010, close of business, 4:30 p.m. (Eastern Standard Time). The Government will not reimburse respondents for any costs associated with submission of the requested information. Telephone inquiries or responses are not acceptable. Responses must be forwarded to Michael.Mills@nrc.gov or responses may be mailed to: U.S. Nuclear Regulatory Commission, Attn: Mr. Michael Mills, Division of Contracts, MS TWB-01-B10M, 11555 Rockville Pike, Rockville, MD 20852. Background The U.S. Nuclear Regulatory Commission (NRC) needs to enhance modification to the beta dose calculation algorithm in the computer code VARSKIN 3.0 : A Computer Code for Assessing Skin Dose from Skin Contamination. The original VARSKIN computer code was initially developed to facilitate skin-dose calculations. This development was under contract to the NRC in 1987 and operated under the DOS operating system. The source geometries available to the user were preset in the code and were limited to a point and an infinitely thin disk located directly on the skin. Self-absorption in the source was not considered because the sources had zero volume and the depth of skin at which dose was calculated was programmed into the code at 7 mg cm -2. These restrictions limited the use of the code. Therefore, NRC released an upgraded version of the code, VARSKIN Mod 2 in 1992. The new version expanded the available source geometries to include cylinders, spheres, and slabs, included calculation of self-absorption in the source, and permitted placement of absorber material between the source and the skin to simulate protective clothing. The user interface was improved, although the code still operated under DOS. The revised version also allowed the dose to be averaged over a volume of skin, permitted calculation of dose from multiple rectangular sources, and permitted composite sources that contained several different beta-emitting radionuclides. The most recent version of the code, VARSKIN 3, added syringe geometry, improved the beta geometry model, and was written to operate in a Windows environment using a graphical interface. In this version, the calculated skin dose can be averaged over any area that is specified by the use at a user specific depth below the skin surface. Provision is made to entering the density of a volume source and for specifying multiple layers of protective clothing between the source and the surface of the skin. The code is used by NRC staff, as well as by licensees and others in nuclear industry, to model and calculate skin dose resulting from hot particles and other forms of skin contamination for regulatory requirements under 10 CFR Part 20. The code calculates the dose due to beta and photon radiations separately using two independent models. VARSKIN 3 calculates beta doses using essentially the same method used in VARSKIN Mod 2 by performing a five-dimensional integration of the source volume and target area using the Berger Point-Kernel method. The gamma dose model in the current version of VARSKIN uses gamma-ray exposure constants to estimate the dose at the desired depth in tissue, and it will not calculate doses for sources that are larger than 1 mm in size. It attempts to account for a lack of charged particle equilibrium using a method developed by Lantz and Lambert. The correction is based on the average energy of the photons emitted by the radionuclide. This adjustment has not been found to provide an adequate correction, and limitations on the size of the source to 1 mm imposes a fairly serious restriction on the utility of the code to calculate skin doses resulting from photon emissions. Although photon doses usually contribute a small fraction to the skin dose resulting from skin contamination (especially in the absence of protective clothing), in some situations the contaminating radionuclide may emit relatively low-energy beta radiation and relatively high-energy gamma radiation. This, coupled with the presence of protective clothing between the contamination and the skin, could lead to a situation in which the gamma dose makes the dominant, if not the only contribution to the skin dose. The resulting doses calculated by the code at various photon energies and at various skin depths have been compared with doses calculated by NRC staff using Monte Carlo transport methods, and were found to overestimate the dose with increasing photon energy (up to a factor of five at 1.5 MeV). The main cause for this lack of accuracy is the inability of the model to adequately allow for lack of charged particle equilibrium at shallow depths at which doses are calculated, normally 7 mg/cm2. The photon model algorithm currently used in VARSKIN 3 also suffers from serious limitations in its applicability to accurately predict dose from sources other than hot particles. This includes being restricted to calculating doses from sources that are not larger than 1 mm using the gamma-ray exposure constant as a basis for the dose estimates. The NRC awarded a contract to Oregon State University in May of 2008 to develop a new sophisticated photon dose algorithm to replace the existing one to address the weaknesses noted above as well to enable the user to reasonably model photon dose for all other source geometries made available in VARSKIN 3. The algorithm should permit the user to select the depth in the skin at which the dose is to be calculated as well as the area of skin over which the dose is to be averaged. Incorporation of the new algorithm must be performed in a manner that it does not in any way result in changes in beta dose model algorithm of the code. In 2008, NRC staff compared the beta and electron doses with the doses for similar geometries calculated using the general purpose radiation transport code MCNP version 5 that was developed and is maintained at Los Alamos National Laboratory. Agreement between the VARSKIN and MCNP results was found to be good in general, but deviated significantly for some contaminant geometries. The reasons were not investigated, but it is believed to be due to the numerical integration methods used to calculate doses from volume sources. The aim of future work on the code is to re-examine these deviations, to determine their cause, and to modify the beta portion of the code to correct the cause. Other modifications to the code may be contemplated, including the possibility of assessing the accuracy of the MCNP calculations of electron doses compared with that for other available transport codes, and the possibility of using other point kernel data besides the Berger data now used in the code, if such data is available. Commercial organizations that are interested in supporting our technical assistance requirements should respond in writing to the market research questions below. Additionally you should provide information on your staff’s qualifications and your firm’s corporate experiences and qualifications on similar contracts or efforts. Market Research Questions: Page Limits – Questions 1 through 7, no more than three (3) pages total. Questions 8 through 10, no more than 6 pages total. 1. How long has your business been in operation? 2. What type of business is your company (i.e. 8(a), large, etc.)? 3. What is the size of your company in terms of employees and consultants? Provide a breakdown of the mix between the two categories. 4. Do you have dedicated office space in proximity to NRC Headquarters in Rockville, MD 20852? (If desired, describe any office space alternatives.) 5. Has your company effectively established teams in the past such that you could perform scopes of work outside your core competencies? (Describe the types of work and technical disciplines assembled.) 6. List any companies, universities, or government agencies your company plans to perform work for related to civilian nuclear reactors or research and test reactors? 7. Has your company previously faced organizational conflict of interest issues with NRC? How were they resolved? 8. Describe any other information your company deems relevant in improving the accuracy of the beta dose calculations for VARSKIN 3 and NUREG/CR-6918. 9. List any beta dosimetry project(s) your company has done in the past? 10. Describe your experience with MCNP and EGSnrc computer codes.
- Web Link
-
FBO.gov Permalink
(https://www.fbo.gov/spg/NRC/OA/DCPM/RS-RES-10-124/listing.html)
- Place of Performance
- Address: U.S. Nuclear Regulatory Commission, 21 Church Street, Rockville, Maryland, 20850, United States
- Zip Code: 20850
- Zip Code: 20850
- Record
- SN02048260-W 20100124/100123000145-66053d40186110e903d7a7a62857cedb (fbodaily.com)
- Source
-
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