[Federal Register Volume 87, Number 61 (Wednesday, March 30, 2022)]
[Notices]
[Pages 18400-18402]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-06619]


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NUCLEAR REGULATORY COMMISSION

[Docket Nos. STN 50-528, STN 50-529, and STN 50-530; NRC-2022-0058]


Arizona Public Service Company; Palo Verde Nuclear Generating 
Station, Units 1, 2, and 3

AGENCY: Nuclear Regulatory Commission.

ACTION: Exemption; issuance.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is issuing an 
exemption in response to a January 14, 2022, request from Arizona 
Public Service Company (the licensee), as supplemented by letter dated 
February 22, 2022. The licensee requested an exemption from NRC 
regulations to remove the diverse auxiliary feedwater actuation system 
using the risk-informed process for evaluations for Palo Verde Nuclear 
Generating Station, Units 1, 2, and 3.

DATES: The exemption was issued on March 23, 2022.

ADDRESSES: Please refer to Docket ID NRC-2022-0058 when contacting the 
NRC about the availability of information regarding this document. You 
may obtain publicly available information related to this document 
using any of the following methods:
     Federal Rulemaking Website: Go to https://www.regulations.gov and search for Docket ID NRC-2022-0058. Address 
questions about Docket IDs in Regulations.gov to Stacy Schumann; 
telephone: 301-415-0624; email: [email protected]. For technical 
questions, contact the individual listed in the FOR FURTHER INFORMATION 
CONTACT section of this document.
     NRC's Agencywide Documents Access and Management System 
(ADAMS): You may obtain publicly available documents online in the 
ADAMS Public Documents collection at https://www.nrc.gov/reading-rm/adams.html. To begin the search, select ``Begin Web-based ADAMS 
Search.'' For problems with ADAMS, please contact the NRC's Public 
Document Room (PDR) reference staff at 1-800-397-4209, 301-415-4737, or 
by email to [email protected]. The request for the exemption was 
submitted by letter dated January 14, 2022, as supplemented by letter 
dated February 22, 2022, and are available in ADAMS under Accession 
Nos. ML22014A415 and ML22053A212, respectively.
     NRC's PDR: You may examine and purchase copies of public 
documents, by appointment, at the NRC's PDR, Room P1 B35, One White 
Flint North, 11555 Rockville Pike, Rockville, Maryland 20852. To make 
an appointment to visit the PDR, please send an email to 
[email protected] or call 1-800-397-4209 or 301-415-4737, between 
8:00 a.m. and 4:00 p.m. (ET), Monday through Friday, except Federal 
holidays.

FOR FURTHER INFORMATION CONTACT: Siva P. Lingam, Office of Nuclear 
Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC 
20555-0001; telephone: 301-415-1564, email: [email protected].

SUPPLEMENTARY INFORMATION: The text of the exemption is attached.

    Dated: March 24, 2022.


[[Page 18401]]


    For the Nuclear Regulatory Commission.
Siva P. Lingam,
Project Manager, Plant Licensing Branch IV, Division of Operating 
Reactor Licensing, Office of Nuclear Reactor Regulation.

Attachment: Exemption

NUCLEAR REGULATORY COMMISSION

Docket Nos. STN 50-528, STN 50-529, and STN 50-530

Arizona Public Service Company, Palo Verde Nuclear Generating Station, 
Units 1, 2, and 3 Exemption

I. Background

    Arizona Public Service Company (APS, the licensee) is the holder of 
Renewed Facility Operating License Nos. NPF-41, NPF-51, and NPF-74, 
which authorize operation of Palo Verde Nuclear Generating Station, 
Units 1, 2, and 3 (Palo Verde), respectively. The licenses provide, 
among other things, that the facility is subject to all rules, 
regulations, and orders of the U.S. Nuclear Regulatory Commission (NRC) 
now or hereafter in effect. The facility consists of pressurized-water 
reactors (PWRs) located in Maricopa County, Arizona.

II. Request/Action

    By application dated January 14, 2022, as supplemented by letter 
dated February 22, 2022 (Agencywide Documents Access and Management 
System (ADAMS) Accession Nos. ML22014A415 and ML22053A212, 
respectively), APS, pursuant to Title 10 of the Code of Federal 
Regulations (10 CFR) Section 50.12, ``Specific exemptions,'' requested 
an exemption from certain requirements of 10 CFR 50.62, ``Requirements 
for reduction of risk from anticipated transients without scram (ATWS) 
events for light-water-cooled nuclear power plants,'' for Palo Verde. 
Specifically, the proposed exemption request would permit Palo Verde 
Units 1, 2, and 3 to eliminate the specific requirement of 10 CFR 
50.62(c)(1) to provide equipment that is diverse from the reactor trip 
system to automatically initiate the auxiliary (or emergency) feedwater 
system under conditions indicative of an ATWS. The Palo Verde diverse 
auxiliary feedwater actuation system (DAFAS) fulfills this requirement 
in 10 CFR 50.62(c)(1), and APS has requested approval to allow 
elimination of DAFAS from the current licensing basis for Units 1, 2, 
and 3 consistent with the proposed exemption. Palo Verde will continue 
to comply with the additional requirement in 10 CFR 50.62(c)(1) to 
provide a diverse turbine trip under ATWS conditions.

III. Discussion

    The regulation in 10 CFR 50.62(c)(1) states:

    Each pressurized water reactor must have equipment from sensor 
output to final actuation device, that is diverse from the reactor 
trip system, to automatically initiate the auxiliary (or emergency) 
feedwater system and initiate a turbine trip under conditions 
indicative of an ATWS. This equipment must be designed to perform 
its function in a reliable manner and be independent (from sensor 
output to the final actuation device) from the existing reactor trip 
system.

    The regulation in 10 CFR 50.62(c)(1) specifically includes the 
requirement to provide equipment that is diverse from the reactor trip 
system to automatically initiate the auxiliary (or emergency) feedwater 
system under the conditions of an ATWS. The Palo Verde DAFAS fulfills 
this requirement. Therefore, the proposed removal of the DAFAS from the 
Palo Verde licensing basis requires an exemption from this section of 
the regulations.
    Pursuant to 10 CFR 50.12, the NRC may, upon application by any 
interested person or upon its own initiative, grant exemptions from 
requirements of 10 CFR part 50 when: (1) The exemptions are authorized 
by law, will not present an undue risk to the public health and safety, 
and are consistent with the common defense and security, and (2) 
special circumstances, as defined in 10 CFR 50.12(a)(2), are present. 
The licensee's submittal identifies in particular that the special 
circumstance associated with this exemption request is that continuing 
to maintain the DAFAS in the licensing basis for Palo Verde Units 1, 2, 
and 3 represents an undue hardship in accordance with 10 CFR 
50.12(a)(2)(iii) due to DAFAS' obsolescence.

A. The Exemption Is Authorized by Law

    The NRC has the authority under 10 CFR 50.12 to grant exemptions 
from the requirements of 10 CFR part 50 upon demonstration of proper 
justification. The licensee has requested a partial exemption to the 
requirement in 10 CFR 50.62(c)(1) to provide equipment to automatically 
initiate the auxiliary (or emergency) feedwater system under ATWS 
conditions that is diverse from the reactor trip system. The licensee 
will continue to meet all other requirements in 10 CFR 50.62(c)(1). As 
discussed below, the NRC staff determined that special circumstances 
exist, which support granting the proposed exemption. Furthermore, 
granting the exemption would not result in a violation of the Atomic 
Energy Act of 1954, as amended, or the NRC's regulations. Therefore, 
the exemption is authorized by law.

B. The Exemption Presents No Undue Risk to Public Health and Safety

    The NRC staff has concluded in the safety evaluation associated 
with this exemption under ADAMS Accession No. ML22054A005 (Enclosure 2) 
that the exemption represents low risk, is of minimal safety impact, 
and that adequate defense-in-depth and safety margins are preserved. 
DAFAS is not credited in the Palo Verde UFSAR Chapters 6 and 15 
accident analyses for actuating AFS to remove residual heat. AFAS is 
the credited means for initiating AFS in the UFSAR analyses as well as 
in the Palo Verde PRA model and will be unaffected by the proposed 
removal of DAFAS. In addition, the NRC staff has concluded that it is 
acceptable for the licensee to credit existing operator manual actions 
within the emergency operating procedures to initiate AFS under ATWS 
conditions as defense-in-depth in support of the requested exemption. 
Thus, granting this exemption request will not pose undue risk to 
public health and safety.

C. The Exemption Is Consistent With the Common Defense and Security

    The proposed exemption will allow the removal of DAFAS from the 
licensing basis for Palo Verde Units 1, 2, and 3 as a diverse automatic 
actuation of AFS under ATWS conditions satisfying partial requirements 
of 10 CFR 50.62(c)(1). The NRC staff has reviewed the exemption request 
in the SE associated with this exemption. The NRC concluded in the 
associated SE that the licensee's submittal demonstrates that the 
reactor protection system, the engineered safety features actuation 
system (ESFAS) and AFAS, and the supplemental protection system (SPS) 
are designed and maintained with high reliability to preclude ATWS 
conditions and are monitored under 10 CFR 50.65, ``Requirements for 
monitoring the effectiveness of maintenance at nuclear power plants.'' 
The NRC staff also concluded that adequate defense-in-depth and safety 
margins will be preserved with the removal of DAFAS from the licensing 
basis for Palo Verde Units 1, 2, and 3. The licensee will continue to 
meet all other requirements in 10 CFR 50.62(c)(1). Further, the 
exemption does not involve security requirements and does not create a 
security risk. Therefore, the exemption is consistent with the common 
defense and security.

[[Page 18402]]

D. Special Circumstances

    The licensee has asserted that continuing to maintain DAFAS in the 
plant licensing basis represents an undue hardship in accordance with 
10 CFR 50.12(a)(2)(iii) due to its obsolescence. DAFAS is no longer 
supported by the vendor and spare parts are not readily available for 
the system. Significant engineering resources are required to reverse-
engineer parts and frequent fiber optic communications problems often 
affect DAFAS system reliability. DAFAS operates on a vendor-supplied 
proprietary platform that is unique to Palo Verde. The vendor is no 
longer in business and Palo Verde can no longer obtain the Modicon 
programmable logic controllers, displays and associated equipment to 
maintain DAFAS. Since these replacement parts can no longer be obtained 
through generally available sources, the licensee has established that 
maintaining or replacing DAFAS in the given circumstances is a 
hardship. Furthermore, the Statement of Considerations associated with 
10 CFR 50.62(c)(1) (49 FR 26038, dated June 26, 1984) state that the 
installation of diverse equipment to trip the turbine and initiate 
auxiliary feedwater have only a marginally favorable value/impact for 
Combustion Engineering plants such as Palo Verde. The NRC staff has 
concluded that the licensee has demonstrated that removal of DAFAS from 
the Palo Verde licensing basis represents low risk and only a minimal 
safety impact. Therefore, the maintaining or replacing of DAFAS in the 
given circumstances is an undue hardship on the licensee. For these 
reasons, granting an exemption to allow removal of DAFAS from the Palo 
Verde licensing basis supports the claimed special circumstance of 
undue hardship.

E. Supplemental Information

    For more technical details, refer to the SE associated with this 
exemption under ADAMS Accession No. ML22054A005 (Enclosure 2).

F. Environmental Considerations

    The NRC staff determined in the associated SE that the exemption 
discussed herein meets the eligibility criteria for the categorical 
exclusion set forth in 10 CFR 51.22(c)(9) because the granting of this 
exemption involves: (i) No significant hazards consideration, (ii) no 
significant change in the types or a significant increase in the 
amounts of any effluents that may be released offsite, and (iii) no 
significant increase in individual or cumulative occupational radiation 
exposure. Therefore, in accordance with 10 CFR 51.22(b), no 
environmental impact statement or environmental assessment need be 
prepared in connection with the NRC's consideration of this exemption 
request.

IV. Conclusions

    Accordingly, the Commission has determined that, pursuant to 10 CFR 
50.12, the exemption is authorized by law, will not present an undue 
risk to the public health and safety, and is consistent with the common 
defense and security. Also, special circumstances are present. 
Therefore, the Commission hereby grants APS an exemption from the 
specific requirement of 10 CFR 50.62(c)(1) to provide equipment that is 
diverse from the reactor trip system to automatically initiate the 
auxiliary (or emergency) feedwater system under conditions indicative 
of an ATWS. As stated above, APS will continue to meet all other 
requirements of 10 CFR 50.62(c)(1) at Palo Verde Units 1, 2, and 3.

    Dated at Rockville, Maryland, this 23rd day of March 2022.

    For the Nuclear Regulatory Commission.

    /RA/

Gregory F. Suber,

Deputy Director, Division of Operating Reactor Licensing, Office of 
Nuclear Reactor Regulation.

[FR Doc. 2022-06619 Filed 3-29-22; 8:45 am]
BILLING CODE 7590-01-P