Steam generator hand hole shielding

Area of Science:

• Nuclear Engineering
• Radiation Protection

Background:

• Pressurized Water Reactor (PWR) operators face increasing radiation dose from steam generator maintenance.
• Preventative maintenance, particularly through secondary side hand holes, is performed without water shielding, increasing exposure.
• Rising work scope for steam generator cleaning and inspection elevates personnel radiation dose.

Purpose of the Study:

• To develop an effective shielding concept for steam generator secondary side maintenance.
• To reduce personnel radiation dose during maintenance activities at Seabrook Station.
• To support the station's goal of maintaining radiation dose ALARA.

Main Methods:

• Development of a novel shielding concept for steam generator secondary side access ports.
• Deployment of the shielding during maintenance activities.
• Estimation of radiation dose savings.

Main Results:

• The shielding concept demonstrated significant dose savings upon initial deployment.
• An estimated 2.5 person-rem (25 person-Sv) was saved during the first use.
• Projected savings of 50 person-rem (500 person-Sv) over the plant's remaining life.

Conclusions:

• The developed shielding concept is effective in reducing radiation exposure during steam generator maintenance.
• This innovation contributes to ALARA goals in nuclear power plant operations.
• The shielding provides substantial long-term radiation dose savings for personnel.