Tag: Gamma

Smear Frisker Cave

This small compact solution replaces larger heavier lead brick caves to reduce background when surveying surface smears and other samples.  The standard size (shown below) has 1” (25 mm) of lead on the top and bottom and 3” (76 mm) of lead on the sides and back.  Caves are built to order and can be […]

Lead Panels and Water Shields

Sometimes the right shield for the job involves placing a shield as close to the source as possible as with pipe and valves shields, but other times the best solution is to put as much shielding as possible into a wall and create general area shielding for the workers. Lead panel shield walls and water shields […]

Conoseals Shielding

This past spring outage season, NPO collaborated with a plant to provide them with custom shielding for their Conoseals during Core Exit Thermocouple replacement activities. Unit 1 and Unit 2 had different Conoseal structures, and the challenge was to model a shielding package that could be used for both elements interchangeably. The shielding package was […]

Core Barrel Shielding

In 2013 NPO designed and built a custom Core Barrel Shield for Palisades Nuclear Plant in Covert, MI.  The shielding was implemented in Palisades’ 23rd refueling outage and was a great success.  The story of the project’s success spread in May 2015 when the Palisades plant was recognized during the Nuclear Energy Institute’s best industry practice […]

MCNP Case Study – Dry Cask Shielding

One year ago we introduced our new ability to simulate complex radiation profiles and thereby design the most effective shielding possible (‘NPO uses MCNP to simulate Dry Cask’, March 2016).  Since then we’ve designed and built more than a few shielding systems using this new ability.  Now the day has finally come where we can […]

T-Flex Pipe and Valve Shields

T-Flex is the most versatile shielding material that NPO has to offer. Its ability to be poured as a liquid and cured as a flexible solid makes it ideal for fitting the maximum amount of shielding around a component while keeping space and weight to a minimum. The most common way this is put into […]

Neutron Shielding – Borated Polyethylene

Borated Polyethylene (BPE) is one of the primary materials NPO uses for shielding Neutron Radiation. Our standard BPE is 5% Boron by weight. The benefit of adding Boron is that capture by B-10 reduces the dose from secondary gamma production. It primarily captures through (n, alpha), and the alphas are easily re-absorbed in the material. […]

Steam Dryer Flood Up Water Shielding

Tungsten T-Flex® was selected as the best material to shield divers during a Steam Dryer repair.   Approval for use in flood up water required chemical testing for leachables and heavy metals.  The end result was an 8 ft x 5 ft (2.44 m x 1.52 m) shield wall constructed by attaching T-Flex panels to a […]

Braidwood Dry Cask Annulus Gap Snakes

Exelon Braidwood Station recently saw very good dose reduction with their dry cask campaigns by utilizing NPO T-Flex® Annulus Gap Shielding. This was designed to fit in the annulus gap between the canister and transfer cask and had a fire blanket covering specified by Braidwood. The annulus gap shielding, in addition to more NPO dry […]

Lower Dry Cask Barrel Shield

Some NPP’s process Dry Casks in a such a way that the entire cask produces a general area dose concern. To reduce these dose rates NPO developed a shield package that sits on the floor and shields the cask to a height of 9 feet (2.74 m). NPO is currently under contract to provide shield […]