ML25322A008
| ML25322A008 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 09/30/2025 |
| From: | Sean Hedger NRC/RGN-IV/DRSS/RCB |
| To: | Sean Hedger, Nestor Makris Pacific Gas & Electric Co |
| References | |
| Download: ML25322A008 (1) | |
Text
From:
Eric Schrader To:
Nestor Makris; Sean Hedger Cc:
Cindy Rosales-Cooper; Don Johnson
Subject:
Diablo Canyon ANS testing inspection concern Date:
Tuesday, September 30, 2025 11:40:10 AM Attachments:
DCPP NRC Allegation - Siren Test.docx Morning Sean, BLUF: The details of the apparent ANS testing discrepancy identified in the most recent program inspection at Diablo Canyon Power Plant (DCPP) were reviewed by FEMA and determined to be acceptable. FEMAs evaluation has been discussed within POB (Cindy Rosalas-Cooper (acting branch chief) and Don Johnson (ROP SME) and Eric Schrader) and determined there is no reason to pursue this inspection concern beyond a licensee failure to comply with a self-imposed standard.
Background:
The attached document is Josh Barnes (FEMA) evaluation of the concerns brought to light during the 2025 September program inspection at DCPP. During the inspection the RG-IV senior EP inspector identified a required 5-year testing requirement contained in the licensees approved ANS design report had not been performed in 2018 and 2023 and that two sirens in 2018 and one siren in 2023 had acoustical outputs < 70 dBC.
The following is a summary of FEMAs review results:
The licensee testing of the ANS appears to be in compliance with the capabilities required in the approved design.
FEMA reviewed the testing results contained in the licensee ANS testing procedure EP MT-43 performed in 2018 and 2023. The testing results showed two sirens in 2018 and one siren in 2023 to be < 70 dBC however determined to not negatively impact the required minimum capability, design and coverage objectives described in FEMA REP-10 and Technical Bulletin 2.0.
The licensee ANS testing procedure EP MT-43 required acoustical siren degradation evaluation to be perform once every 5-years and evaluated against historical sound data is not a FEMA ANS requirement and likely a self-imposed standard created by the licensee. FEMA ANS requires a process to be used to periodically evaluate or verify the validity of data and capabilities. The standard chosen by the Licensee and the ORO is a self-imposed one.
FEMA recommends the EP MT-43 be updated and include the minimum level capability (REP-10 and Tech Bulletin 2.0) as the threshold for determining degradation or approaching degradation of capability.
Eric Schrader All I want from tomorrow is to get it better than today Huey Lewis.
ADAMS Accession # ML25322A008
US Nuclear Regulatory Commission Emergency Preparedness Specialist NSIR/DPR/POB Two White Flint North 11545 Rockville Pike Rockville, MD 20852-2738 (301) 287-3789
To Narvaez Stinson:
x From FEMAs perspective, was/is the licensee in compliance with ANS design report commitments for acoustical testing?
o The Licensee appears to be in compliance.
o FEMA would recommend that the language be updated to define acoustical value significance since FEMA evaluates changes in capability.
x Are the deviations from the testing and evaluation procedure acceptable to FEMA?
o If EP MT-43 does not align with the regulators expectation, it would be difficult for us to provide feedback the licensees E-plan procedure.
o If we could provide any feedback, it would be pointing to our guidance that defines acoustical value significance.
x Given the test data in some cases did not meet the sirens design coverage objectives, is the amount of indicated deviation from the objective levels enough to warrant corrective action from the licensee?
o The test data does indicate the coverage objectives are still being met per guidance set forth in FEMA REP-10 or Technical Bulletin 2.0.
x Given the test data results for 2018 and 2023, do any of the sirens tested show degradation? If so, is the amount of degradation acceptable? (It is recognized that finding out more historical data from the licensee will help in this point.)
o In FEMAs view any degradation detected has not impacted in capability and the design objectives noted in the RPM are being met.
o Instead, preventative maintenance should be considered to avoid trends in degradation and crossing that capability threshold
Control Point 3 NRC: In 2018 and 2023 Siren #3 failed to meet the 70dcb level.
FEMA: The Design Report materials indicate #3 - Location: SLO, intersection of Bishop St and Florence Ave, Latitude 35.270657, Longitude -120.651295. The DCPP 2023 EWS Siren Test states on pg. 7, that the location peaks at or above 70 dBC, and should be enough as the two sirens covering that location are rotating sirens and as the monitoring demonstrates will peak when the siren rotates to aim directly at the control point and continues to act as an attention signal.
Discretionary Point 4 NRC: In 2018, the sound output at the Discretionary Point 4 siren was in the 65-68 dBC range, failing to meet the same design coverage objective of 70 dBC.
FEMA: The Design Report materials indicate Discretionary Point 4 at 35.110600. -120.573400, near Arroyo Grande CA, should be at 70 dBC. However, the location measured is in a low-density area and per REP-10 guidance only needs 60 dBC and 10dBC over ambient. The DCPP 2023 EWS Siren Test confirms this on pg. 7.
Discretionary Point 5 NRC: In 2023, the sound output at the Discretionary Point 5 siren was in the 66-68 dBC range, failing to meet the same 70 dBC design coverage objective.
FEMA: The Design Report materials indicate Discretionary Point 5 at 35.251694, -120.633989, near San Luis Obispo CA, should be at 70 dBC and according to the map the location measured is in a low-density area and per REP-10 guidance only needs 60 dBC and 10dBC over ambient. In viewing the satellite imagery, the density map needs to be re-evaluated as new neighborhood in that location would change it potentially to a high-density area and need 70 dBC. However. the DCPP 2023 EWS Siren Test states on pg. 7, that the location peaks at or above 70 dBC, and should be enough as two of the three sirens covering that location are rotating sirens and will peak when the siren rotates to aim directly at the discretionary point` and continues to act as an attention signal.
Source for verification: Diablo Canyon Power Plant Early Warning System ISO9613 Acoustical Coverage and Demographic Overlay v. 2013 (Isopleths Predicted by Federal Signal Corp. SureWarn Sound Propagation Analysis Software)