ML20107G015
| ML20107G015 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 04/12/1996 |
| From: | Borst F PUBLIC SERVICE CO. OF COLORADO |
| To: | Weber M NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| P-96028, NUDOCS 9604230072 | |
| Download: ML20107G015 (3) | |
Text
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h Public Service'
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f 16805 WCR 191/2; Platteville, Colorado 80651 April 12,1996 f
Fort St. Vrain P-96028 i
l U.S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, D.C. 20555 ATTN:
Mr. Michael F. Weber, Chief Decommissioning and Regulatory Issues Branch Docket No. 50-267
SUBJECT:
FSV Final Survey Plan - Aggressive Decontamination Methods
REFERENCE:
PSCo Letter, Fisher to Weber, dated October 12,1995 (P-95077)
Dear Mr. Weber:
1 This letter provides supplemental information to clarify Public Service Company of l
Colorado's (PSCo) position regarding aggressive decontamination of embedded piping j
system surfaces at Fort St. Vrain (FSV). In the referenced letter, PSCO requested NRC l
approval to fill embedded pipes with grout where they cannot be decontaminated to less j
than the site-specific guideline values using aggressive decontamination methods. PSCo described typical decontamination processes, but we have not previously defined a l
4 minimum effort that we would consider as aggressive decontamination. This letter is submitted in response to questions raised by Messrs. Clayton Pittiglio and David Fauver l
of your staff.
As indicated in the referenced letter, PSCo and the Westinghouse Team (WT) use several l
different techniques to decontaminate embedded piping sections, depending on various l
factors such as accessibility of the pipe opening, configuration of the pipe, size of the pipe, level of contamination, form of contamination, and ALARA considerations, j
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P-96028 April 12,1996 Page 2 PSCo/WT define aggressive decontamination for embedded piping system surfaces as follows:
A.
For Systems With High Potential for Contamination At least four passes of grit blasting, hydrolazing, or abrasive balls will be j
performed on embedded pipes in this category that do not meet the Site Specific Guideline Values (SGLVs).
Systems in this category include piping exposed to:
Primary coolant (e.g., PCRV instrument and relief valve penetrations),
Shield water (e.g., core support floor tubes),
Radioactive liquid or gaseous wastes, and Debris from contaminated equipment or spent fuel (e.g., equipment 1
storage well and fuel storage well vents and drains).
B.
For Systems With Low Potential For Contamination i
Pipes will be at least wiped or wire brushed until the ends are free of visible slurry or residue and until a cloth passing through the pipe meets a criterion 2
equivalent to 75% of the removable SGLV (750 dpm/100 cm).
This is determined by adjustment of the wipe measurement for the size and length of the pipe being surveyed, and for the efficiency of the detector; an additional factor of 10% is applied for conservatism. For example, for 1-inch diameter,10 foot long pipes, the acceptance criterion is determined as follows:
2 750 dpm/100 cm x 75% x 10% (For Conservatism) x 20% (Efficiency of LMI 43-68 Detector) x 25 (Area Factor -- surface area is approximately j
2500 cm ) = 281 com; as a conservative measure, 250 cpm above 2
background is actually used.
Systems in this category include piping exposed to concrete cutting slurry during decommissioning, such as PCRV cooling system sidewall tubes, tendon tubes, and miscellaneous penetrations. These pipes include removable contamination, with low potential for fixed contamination.
PSCo/WT consider that these decontamination methods represent an appropriately aggressive effort to reduce removable contamination levels to much less than the SGLVs and total contamination levels as low as reasonably achievable. Based on our current measurement data, total contamination levels in embedded pipes after decontamination 2
2 are typically less than 4,000 dpm/100 cm (average) and 12,000 dpm/100 cm (individual
s P-96028 April 12,1996 Page 3 2
2 are typically less than 4,000 dpm/100 cm (average) and 12,000 dpm/100 cm (individual measurement). However, for those embedded pipes in a survey unit where the SGLVs are not met after aggressive decontamination, PSCo proposes to fill them with grout, as described in the referenced letter.
PSCo/WT are performing the above aggressive decontamination program on all contaminated embedded piping at Fort St. Vrain; however, there are a few pipe sections whose configuration or other obstructions physically preclude complete decontamination or surveying. For example, PSCo identified in our March 5,1996, response to NRC comments (P-96009), that approximately 10 out of 276 core support floor column tubes were found to be coated with epoxy or to have other obstructions that precluded effective hydrolazing. Other obstructed pipes may be identified as our decontamination efforts progress, and they will be decontaminated to the extent reasonably possible. These exceptions are very few and will be documented in the Final Survey Report.
If you have any questions regarding this information, please contact Mr. M. H. Holmes at (303) 620-1701.
Sincerely, hdtQ 0 19 Frederi [ Borst Decommissioning Program Director FJB/SWC cc:
Regional Administrator, Region IV Mr. Robert M. Quillin, Director Radiation Control Division Colorado Department of Public Health and Environment