ML24067A009
| ML24067A009 | |
| Person / Time | |
|---|---|
| Site: | Nuclear Energy Institute |
| Issue date: | 03/08/2024 |
| From: | Lafountain S, Pimentel F NRC/NRR/DRA/ARCB, Nuclear Energy Institute, Southern Co |
| To: | |
| References | |
| Download: ML24067A009 (6) | |
Text
©2024 Nuclear Energy Institute 1 Sam Lafountain, Lead Engineer, Southern Company Frankie Pimentel, Sr. Project Manager -
Engineering & Risk, NEI March 8, 2024 Discussion of On-site and Off-site Dose Criteria in RG 1.183
©2024 Nuclear Energy Institute 2 Supporting Documents for Change to CR Design Criteria
Review of Control Room Design Criteria and Radiological Health Effects ML23027A059
"Design Criteria" do not represent actual or expected occupational exposures but rather are "figures of merit" used to confirm performance and requirements for SSCs important to safety
The control room design criteria are not intended to be operational limits and should not be used to imply what is an acceptable exposure during emergency conditions
The limit for occupational exposures remains 5 rem TEDE per 10CFR20
Dose Constraints for planned special exposures allow up to 10 rem (provided lifetime exposure does not exceed 25 rem)
the control room design criteria are applicable to a low-frequency event, whereas the planned special exposure is designed for a more likely routine radiological exposure event. Based on a potential radiological risk each rule is intending to protect against, the applicable dose constraints for less likely emergency events should be aligned (higher) than the dose constraints for the lower frequency events (planned special exposures) at 0.10 sievert (Sv) (10 rem) as well as routine occupational exposures 0.05 Sv (5 rem).
©2024 Nuclear Energy Institute 3 Supporting Documents for Change to CR Design Criteria 2013 PAG Manual The PAG manual appears to be in alignment with a frequency/probability-based approach for acceptable exposures Guideline Activity 5 rem Occupational Exposures 10 rem Protecting valuable property necessary for public welfare (e.g. a power plant) 25 rem Lifesaving or protection of large populations
©2024 Nuclear Energy Institute 4 Proposed Changes To Table 7 (RG-1.183 R1)
©2024 Nuclear Energy Institute 5 Supporting Information for Table 7 Changes Based on review of Baseline Risk Index information presented in workshop
- 2, there is a clear demarcation between SGTRs / other non-LOCA transients (CDF ~ 1E-06 yr-1) and LOCAs (CDF ~ 1E-09 yr-1)
For non-MHA events, proposed CR and offsite criteria at 10 rem TEDE
Exception - Events with current offsite criterion of 25 rem (e.g., pre-accident spike) left unchanged
Consistent with low end of proposed range in IE rulemaking basis document
No observed health effects - Health Physics Society Position Statement PS010-4, Radiation Risk in Perspective, January 2020, states in part, below levels of about 100 mSv (10 rem) above background from all sources combined, the observed radiation effects in people are not statistically different from zero.
©2024 Nuclear Energy Institute 6 Supporting Information for Table 7 Changes
For MHA LOCA, proposed CR and offsite criteria at 25 rem TEDE
Offsite criterion unchanged from what is in 50.67 now
Reflects extremely low probability and its use as a design criterion (i.e., does not represent actual or expected occupational exposures)
Releases from a LOCA based on a 10 CFR 50.46 compliant thermal-hydraulic analysis are many orders of magnitude less than what is postulated in MHA LOCA
Considering the importance of control room habitability, the selection of updated values for control room design criterion should be more aligned with the various U.S.
and international organizations recommendations for emergency dose limitations
25 rem is consistent with PAG manual guidance for activities involving lifesaving or protection of large populations
Less than IAEA GSR Part 71 guideline for restricting exposure of emergency workers performing lifesaving actions (50 rem)
Does not change the occupational dose limits in 10 CFR 20 1 - P_1708_web.pdf (iaea.org)