DE-TECT Unit Inspection - SA Based welding inspection, flaw detection, examination & piping surveys

COMPILATION OF SPONGE JET USE IN RADIOLOGICAL DECONTAMINATION APPLICATIONS

Overview

Sponge-Jet is an innovative commercial and industrial surface preparation technology. This dry, low dust process requires minimal containment, reduces downtime and offers a wide range of surface profiling. Reusable abrasive, or non-abrasive, Sponge media can be used on the toughest to the most sensitive surfaces. The Sponge-Jet system offers fast, dry, clean, safe and flexible industrial surface preparation at a total job cost often lower than traditional blasting.

Sponge media is an open-celled polyurethane particle impregnated with abrasives. As a result, it has several cost, time and money saving benefits. The pliant nature of Sponge-Jet Sponge media allows its particles to flatten on impact exposing the abrasive. After leaving the surface, the media constricts, pulling and entrapping most of what would normally have become airborne contaminants.

The blasting system consists of a Feed Unit and a Classifier. The Feed Units deliver Sponge media to the surface. Feed Units are designed to meet the specific flow characteristics of Sponge media. An actuator inside every blast pot stirs the Sponge media to keep it flowing, while an augur at the base of the Unit controls the amount of media fed into the air stream. A pneumatic control panel provides precise adjustment of blast pressure and media feed rate.

The Classifier prepares and cleans the media for recycling. Blasted media is collected and processed through either an electrically or pneumatically powered Classifier. This separates the Sponge media into three categories: oversized debris, reusable media and fines (consisting of spent media and dust). Typically, between 60% and 90% of Sponge media is reusable after each blast cycle.

Introduction

The Sponge Jet system was originally designed and manufactured for use in non-radiological applications such as coating removal and surface preparation. As its capabilities developed and became more widely known, numerous end users undertook various test projects to evaluate the system's applicability to nuclear decontamination tasks. That the result of these projects was favorable is evident from the fact that many of the initial evaluative efforts led to follow on commercial production use of Sponge Jet technology in the nuclear marketplace.

This information provides a preliminary summary of the radiological decontamination tasks to which Sponge Jet has been applied in both the commercial and non-commercial branches of the nuclear industry.

The Sponge Media

The media designed for use in the Sponge Jet system, by nature of its physical characteristics and kinetic behavior, lends itself naturally to use in the necessarily controlled environment of radiological decontamination. The media deforms upon substrate impact, resulting in a much less elastic (more plastic) impact than exhibited by more conventional impact media (e.g., sand, metal grit, etc.), resulting in lower magnitude of rebound impact on operator, equipment and/or protective clothing. It also has a fairly high void space to solid media ratio, allowing the sponge media to retain removed contaminants. This property gives the media low dust generation properties and reduce the risk of potential cross contamination during spent media removal and waste packaging.

Applications

The Sponge Jet system has been used by end users in a variety of configurations and applications. The applications range from routine decontamination tasks performed with the standard Sponge Jet system machinery to specialised decontamination projects in which application-specific equipment was designed and built to augment standard sponge media delivery systems in a manner appropriate to the tasks at hand. Following is a brief compilations of Sponge Jet's nuclear applications to date.

Pipe End Decontamination During Steam Generator Replacement Projects (SGRP):

When commercial nuclear generation facilities must, for a variety of reasons, replace their steam generators (SG), the primary piping sections that are cut to allow removal and replacement of the SG can be a significant source of personnel radiation exposure.

Specialised nucelar service firms, notable Framatome Technologies and AEA Technologies Engineering Services, have used sponge media delivered through proprietary engineered additions to the Sponge Jet delivery systems to effect pipe end decontamination at numerous nuclear power plants, in both the United Sates and abroad. The results of these projects has been quite favorable.

Decontamination factors (DF) in this application indicate the factors by which exposure, or dose, rate is reduced by the technology applied. This measurement is somewhat problematic, given that the surface being decontaminated is not the only major contributor to area dose rates. Nonetheless, reductions in overall dose rates in a range from three to ten have been documented in repeated uses of these systems. A sampling of "before and after" measurements in presented in the table below:

Facility	Pre-Decon Dose Rate (Mean, in mR/hr)	Post-Decon Dose Rate (Mean, in mR/hr)	Decon Factor	% Dose Rate Reduction
Maguire 1	1990	630	3.29	87.5%
Catawba	3055	850	3.83	82.3%
N. Anna	5400	1900	3.75	75.8%
V.C. Summer	6000	1000	4.94	74.8%
C.N. de Almarez	2500	700	2.78	55.3%

Notes:

1) % dose rate reduction data includes shielding factors
2) All dose rate readings obtained at the plane of the pipe end opening
3) Data shown represents averages of reported data on individual components

General decontamination of By-Product Material:

Several production scale projects are ongoing. While data is currently being gathered on these efforts, a preliminary summary as follows:

Entergy, Inc. is using Sponge Jet system at its Arkansas Nuclear One site in Russelville, AK to perform a variety of surface preparation and decontamination tasks, including decontaminating and preparing the inside surfaces of interim spent fuel storage casks.

At Florida Power and Light's St. Lucie Nuclear Plant, Sponge Jet was used to remove boric acid residues from the reactor head bolt flange and to clean the reactor head scal ring area during a recent planned outage. Additional work of this type is planned for an upcoming outage.

General Decontamination Tasks on Nuclear Fuel/Uranium Sites:

Sponge Jet has been used effectively in demonstration scale facility decontamination as well as in production scale decontamination and decommissioning projects.

Currently underway, the Formerly Utilised Sites Remedial Action Project (FUSRAP) project at Paxair in Tonowanda, NY is employing Sponge Jet technology in this site remediation project. Published results of this project are unavailable as of this writing, however anecdotal accounts indicate that Sponge Jet is meeting or exceeding its performance objectives at this site.

Conclusions

The Sponge Jet decontamination system has proven to be quite effective in a variety of radiological decontamination applications to date. Given Sponge Jet, Inc's traditional emphasis as a materials supplier for non-nuclear applications, the effort to gather evidentiary data as to the product's effectiveness in the nuclear marketplace is currently in its initial stages. Additional data collection on the system's performance in a variety of application is ongoing. Based on currently available data, the Sponge Jet system exhibits great promise as a potent tool in pursuit of successful nuclear facility and radioactive material decontamination and decommissioning projects.

REMOVAL OF RADIOACTIVE OXIDE BUILD-UP FROM REACTOR COOLANT PIPING

Problem

Nearly 9m 2 (100 ft 2 ) of highly radioactive oxide build-up (measuring 8,000 to 12,000 millirem) on stainless steel reactor coolant piping in an eastern U.S. nuclear power plant needed to be removed. Utility representatives requested that no appreciable loss of the stainless steel substrate occur and specified an overall surface profile of less than 60 micron (2.5 mils).

The Contractor, an international nuclear services organization, was contracted to remove the oxide layer with minimal substrate damage

and safely decontaminate the pipe below 100,000 dpm smearable so other outage maintenance could be conducted.

Solution

Using Silver Sponge Media TM and the Sponge-Jet Sponge Blasting System, TM the contractor successfully removed the oxide layer, reducing

radiation contamination levels to less than 100,000 dpm, while leaving less than a 60 micron (2.5 mil) substrate profile - all in one pass. The utility was pleased with the post

decontamination levels achieved, the overall cleanliness of the operation, and most of all, how quickly the job was completed. As a result, the contractor has successfully conducted similar pipe-end decontamination projects in 8 other nuclear facilities throughout the world.

Goals:	Alternatives considered:	Contractor's choice:	Contractor:
- Low dust generation - Clean, dry process - Low waste generation - Cost competitive	- Hand tooling - Chemical stripping - CO₂ pellet blasting	Sponge-Jet Sponge Blasting System™ Silver Sponge Media™	AEA Technology Engineering Services Jim Flaherty Marketing Manager Pittsburgh , PA 412-655-1200

“What a process! It amazes me how Sponge-Jet Silver Sponge Media contains the contaminated particles…it's also compressible for waste management purposes.”
Brad Fasel, Process Engineer

Sponge-Jet's Sponge Blasting System™

Problem
INEEL's Decontamination and Decommissioning project needed to reduce worker exposure and stress during decontamination of concrete and metal surfaces.

Baseline Technology
Conventional wipe-down and scabbling to remove surface contamination.

Innovative Technology
The Sponge-Jet's Sponge Blasting System™ propels a proprietary sponge-like media to remove and bind surface contamination.

Comparison
This surface cleaning system increases productivity, reduces worker stress and exposure.
Blast media can be recycled. Elevated noise limits work time.