Discrete Radioactive Particle Issues Associated with a Fuel

Discrete Radioactive Particle Issues Associated with a Fuel Pool Cleanout Project 5/19/2021 PPL Susquehanna LLC 1

Richard L. Doty and Richard C. Kessler 5/19/2021 PPL Susquehanna LLC 2

Management of Contamination Control Ø Measurement Ø Management Ø Perception Ø Culture 5/19/2021 PPL Susquehanna LLC 3

What’s a Discrete Radioactive Particle (DRP)? ØA DRP is defined as a fragment that is less than 1 mm in any dimension (typically 10 -20 microns in diameter) with a specific activity greater than or equal to 50, 000 cpm. 5/19/2021 PPL Susquehanna LLC 4

OVERVIEW Ø Project began in late June 2000 Ø Control Rod Blade (CRB) processing began in July Ø First particle exposure to a worker (0. 12 Sv, SDE) was documented on September 8 th 5/19/2021 PPL Susquehanna LLC 5

Ø First high activity particle (20 m. Gy/h) was identified on September 11 th Ø During removal of the Advanced Crusher Shearer on October 12 th, a particle was identified with a measured contact dose rate of 8 Sv/h (a Telescan® was used). Ø Co-60 was identified via in-situ gamma spectroscopy 5/19/2021 PPL Susquehanna LLC 6

Ø On November 28 th, a high activity particle was measured at 2. 2 Sv/h on a cask. Ø On December 6 th, a high activity Co-60 particle was identified on a worker’s shoe cover. The measured contact dose rate was 10 m. Sv/h. Ø Overall, 36 particles were identified between September 8 th & December 15 th. 5/19/2021 PPL Susquehanna LLC 7

During the project, no individual was exposed to doses in excess of SSES or regulatory dose limits. 5/19/2021 PPL Susquehanna LLC 8

Assessments Ø DRP of 8 Sv/h Ø Series of DRP events Ø Project management Ø Independent oversight of project Ø Critique of event evaluations 5/19/2021 PPL Susquehanna LLC 9

8 Sv/h Co-60 DRP on skin can result in: 2, 900 Gy/h shallow dose equivalent 2. 3 Gy/h deep dose equivalent 5/19/2021 PPL Susquehanna LLC 10

Regulatory Issues Ø Significance Determination Process (SDP) identified a White Finding Ø Notice of Violation - 10 CFR 20. 1501 5/19/2021 PPL Susquehanna LLC 11

Ø From the NRC Inspection report: “…(SSES) did not adequately evaluate and characterize the radiation exposure hazards posed by radioactive particles having highly significant activity. ” 5/19/2021 PPL Susquehanna LLC 12

Ø From the NRC Inspection report: “…(SSES) did not establish and implement adequate radiological safety controls to prevent shallow dose equivalent (SDE) and deep-dose equivalent (DDE) personnel exposures from exceeding regulatory requirements. ” 5/19/2021 PPL Susquehanna LLC 13

INPO Ø Preliminary Operating Experience Report - Issued December 27, 2000 Ø Assist Visit Recommendations - January Ø Significant Event Report (SER) 3 -01 Issued March 30, 2001 5/19/2021 PPL Susquehanna LLC 14

SER 3 -01 Recommendations Ø Documented guidance for establishing “HPCZ” Ø Thorough pre-job briefings Ø Well-developed contamination control methods, considering all applicable industry events Ø Senior management presence and communication of high standards 5/19/2021 PPL Susquehanna LLC 15

WANO SER 2001 -2 Ø Risk assessments considering prior experience Ø Contingency work plans for high-risk evolutions Ø Thorough pre-job briefs and shift handovers 5/19/2021 PPL Susquehanna LLC 16

Susquehanna Perspective on Root Causes ØInaccurate risk perception for exposure to DRP ØProcess focus on actual doses vs. potential doses ØInadequate pre-job plans for DRP controls ØUnresolved cultural issues regarding questioning attitude, communications, use of operating experience 5/19/2021 PPL Susquehanna LLC 17

What Have We Learned Ø Lack of sensitivity to the consequences of highly radioactive material (particles) (Root Cause 2) Ø Attitude that significant radiological events can’t happen at SSES 5/19/2021 PPL Susquehanna LLC 18

What Have We Learned Ø Particle assessments focused on actual doses versus potential doses (Root Cause 2) Ø Inadequate pre-job plans were developed for the FPCO project for the control of particles (Root Cause 4) 5/19/2021 PPL Susquehanna LLC 19

What Have We Learned Ø We need to improve control of radioactive material on refueling floor and in potentially impacted systems 5/19/2021 PPL Susquehanna LLC 20

What Have We Learned Ø The associated vacuuming and filtration of the cask storage pit (CSP) were less than adequate to control the DRP source term. Ø Rinsing of all items that were removed from the CSP and fuel pools was not performed for every evolution. 5/19/2021 PPL Susquehanna LLC 21

What Have We Learned Ø Need to structure pre-job briefings for hot particle control zone (HPCZ) work Ø Need specific RWPs for HPCZ work Ø Need to consider the use of respiratory protection to prevent the intake of particles 5/19/2021 PPL Susquehanna LLC 22

What Have We Learned Ø Radiation Protection Technicians needed more training on DRP survey and containment techniques Ø Self-assessment program was not sufficiently risk-oriented 5/19/2021 PPL Susquehanna LLC 23

Corrective Actions Ø Revised RP procedures to enhance radiological controls Ø Survey techniques Ø Labeling and posting Ø Dose rate limits and dress requirements Ø Control of radioactive material 5/19/2021 PPL Susquehanna LLC 24

Corrective Actions Ø Treat high risk/high consequence evolutions as special evolutions Ø Add management oversight for high risk activities Ø Focus self-assessment program 5/19/2021 PPL Susquehanna LLC 25

Summary Ø Be proactive to potential conditions rather than reactive to emergent conditions Ø When the mindset exists that “it can’t happen here, ” it will 5/19/2021 PPL Susquehanna LLC 26

INPO Ø SER 4 -98 addressed precursors for unplanned exposures Ø Three of the root causes aligned with the SER precursors 5/19/2021 PPL Susquehanna LLC 27

INPO SER 4 -98: Common Event Precursors Ø Ø Ø Inaccurate or incomplete radiological surveys Inadequate work planning and radiation work permits Incorrect guidance provided by radiological protection technicians Non-compliance with radiological protection rules Ineffective supervisory and management direction and oversight 5/19/2021 PPL Susquehanna LLC 28

Defense in Depth Ø Strong management Ø Comprehensive planning Ø Accurate risk perception Ø Culture of awareness and risk control Ø Good measurement processes 5/19/2021 PPL Susquehanna LLC 29

QUESTIONS? 5/19/2021 PPL Susquehanna LLC 30