[Global] Work in CTMT at Power

[Parlone Richard]

Morning Krystyn,

For Sizewell B (4 loop Westinghouse SNUPPS, 1200 MWe), we have 2 planned Containment Entries at Power in an 18 month operating cycle, and normally allow dose in the annual plan for one emergent entry.

The planned entries include a Tech Spec surveillance programme boric acid walkdown of accessible annulus areas and access to our Flux Mapping Platform and Pressuriser Cell (VHRA areas). This is the highest dose activity. Also included is the collection of a reactor leak-off sample and some other sundry routines. Entrants are issued with Thermo EPD-N2s which are our "legal record" dosimeters for neutron and gamma.

We typically plan for 2 person.millisieverts (200 person.mrem) of neutron and gamma dose when scoping the annual dose budget a year in advance, based upon "expected" activities. The last entry in September 2025 was delivered for 1.3 p.mSv (130 p.mrem). Our annual dose for 2025 to date is 2.176 p.mSv (~220 p.mrem) for two entries.

There is a justification flow chart to include other work in a planned entry, which I have attached. Basically it reflects whether there is a significant nuclear safety impact to the work, or work is needed to prevent a reactor trip or power reduction and whether the work can be performed in an outage.

Regards,
Richard

Richard Parlone
Head of Radiological Protection
Technical & Safety Support Department
EDF Nuclear Operations
Sizewell B Power Station, Suffolk, United Kingdom IP16 4UR
T: (+44) (0)1728 65 3750 (Internal 718 3750)

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From: Global <global-bounces at list.rpalara.org> On Behalf Of Kono, Krystyn M via Global
Sent: 11 November 2025 15:33
To: 'global at list.rpalara.org' <global at list.rpalara.org>
Subject: [Global] Work in CTMT at Power

What is your yearly dose for work in CTMT at Power?  What is the criteria for work in CTMT at power to be worked?

Krystyn Gowdy Kono
Xcel Energy
Radiation Protection - ALARA Foreperson
Prairie Island Nuclear Generating Plant
1717 Wakonade Dr, Welch, MN 55089
P: 651-267-6556
E: krystyn.kono at xcelenergy.com<mailto:krystyn.kono at xcelenergy.com>

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