ML22271A885

Nuclear Utility Group on Equipment Qualification (Nugeq)S Concern with Generic Implications Clarification

ML22271A885
Person / Time
Site:	Diablo Canyon
Issue date:	09/27/2022
From:	Horin W Nuclear Utility Group on Equipment Qualification, Winston & Strawn, LLP
To:	Vincent Gaddy NRC/RGN-IV/DORS/EB1
Gaddy V
References
IR 2022011
Download: ML22271A885 (4)

Text

NUCLEAR UTILITY GROUP ADAMS Accession no. ML22271A885

ON EQUIPMENT QUALIFICATION

WINSTON & STRAWN LLP 1901 L STREET, N.W.

WASHINGTON, D.C. 20036-3506

TELEPHONE (202) 282-5737 September 27, 2022

VIA: U.S. Mail and email:

Vincent G. Gaddy, Chief Engineering Branch 1, Region 4 Division of Operating Reactor Safety 1600 East Lamar Boulevard Arlington, Texas 76011-4511

Re: NUGEQs Concern with Generic Implications and Request for Clarification Stemming from the Classification of Performance Deficiency under Diablo Canyon TEAMS IR-2022011 as a 10 C.F.R. § 50.49(e)(1) Non-Cited Violation (NCV)

Dear Mr. Gaddy:

The Nuclear Utility Group on Equipment Qualification (NUGEQ or Group)1 hereby submits this letter as a result of the Groups review of the Green Finding and NCV levied against Pacific Gas & Electric/Diablo Canyon on August 9, 2022. Specifically, in Inspection Report 05000275/2022-011 and 05000323/2022-011, inspectors identified a performance deficiency associated with a violation of 10 C.F.R. § 50.49(e)(1). The performance deficiency was triggered by the licensees2 failure to include the most severe temperature at the 480 VAC switchgear, and the 125 VDC battery charger/inverter rooms resulting from a postulated design basis tornado event in the electric equipment qualification program. 3 As noted in the inspection report, the inspectors expressed the view that the increase in room temperature caused by the design basis tornado event meant that the 480 VAC switchgear rooms and the 125 VDC battery charger/inverter rooms were no longer mild environments when compared to normal room temperature limits.

As a result, inspectors further expressed the view that the electric equipment in those rooms would need to be qualified to remain functional for the anticipated temperatures during the duration of a design basis tornado event. The inspectors concluded that [s]ince the licensees

1 The Group represents approximately 75% of the operating nuclear power plants in the United States. The Group was founded in 1981, as the NRC staff was evaluating and planning the ultimate promulgation of 10 CFR 50.49, Environmental qualification of electric equipment important to safety for nuclear power plants.

2 PG&E is not a current member of the Group.

3 ML22215A284 Vincent G. Gaddy September 27, 2022 Page 2

electric equipment qualification program was not based upon the time-dependent temperature in those rooms resulting from the most severe design basis event[,] the licensee was in violation of 10 CFR 50.49. It appears that the basis for the vi olation stems from the staffs position that the application of the conditions resulting from a design basis event (DBE) (in this case a tornado, e.g., a natural phenomenon) are coincident to the conditions from a design basis accident (DBA),

which are addressed under § 50.49(e).

The Group takes no formal position on the merits of whether the licensee should or should not respond to the performance deficiency. From a generic perspective, however, the Group is concerned with the implications of the analysis and conclusions memorialized in the IR with respect to future inspections that could impact our Group members. In particular, section 50.49(e)(1) specifically requires an EQ program to include and be based on the time-dependent temperature and pressure at the location of the el ectric equipment important to safety for the most severe design basis accident (DBA4) during or following which this equipment is required to remain functional. Since DBAs are a subset of DBEs, these terms have different meanings and are not interchangeable. In effect, the violation basis of the Green finding incorrectly expands the applicability of § 50.49(e)(1) beyond design basis accidents to include natural phenomena or external events, such as a tornado, which is contrary to the specific exclusion of those conditions from 10 C.F.R. 50.49. See 10 CFR § 50.49(c).

The NRC has been clear on this distinction since the promulgation § 50.49 in 1983. In fact, this issue was raised and addressed during public comments on the rule. The NRCs response resulted in the exclusion of natural phenomena and external events as specifically delineated in the Statement of Considerations.5 The exclusion of natural phenomena or external events such as tornados from the scope of EQ programs is also reflected in Chapter 3.11 of NUREG-0800 as well as in RG 1.89 Revision 1.6

The postulated temperature conditions within the 480 VAC switchgear rooms or the 125 VDC battery charger/inverter rooms from a tornado are not within the scope of the EQ final rule since a tornado is a natural phenomenon. These conditions are addressed external to an EQ program, consistent with GDC-2 and GDC-4. As such, § 50.49 is not applicable to environmental conditions from tornados. The converse interpretation delineated in the Diablo Canyon IR is

4 Design basis accidents are a subset of design basis events as defined by 10 CFR 50.49(b)(1)(ii).

5 [T]he Commission has concluded that protection of electric equipment important to safety against other natural phenomena and external events should not be within the scope of this rule. See 48 Fed. Reg. 2,731 (01/21/1983).

6 Reviews to determine compliance with related requirements for (1) dynamic and seismic qualification of electrical and mechanical equipment, (2) protection of electric and mechanical equipment against other natural phenomena and external events are described in other SRP sections. See NUREG-0800, 3.11 Environmental Qualification of Mechanical and Electric Equipment, at p. 3.11-2. See also, RG 1.89, Rev. 1, Section A: Section 50.49 does not include requirements for protection of electric equipment against other natural phenomena and external events, and equipment located in a mild environment.

Vincent G. Gaddy September 27, 2022 Page 3

erroneous and would pose significant generic implications on existing EQ programs if so applied.

Request for Clarification

Given the generic implications of the NCV cited to § 50.49(e)(1), the Group requests Staff clarification that §50.49 EQ programs must include or be based on the time-dependent temperature and pressure conditions for the most severe design basis accident during or following which this [electrical] equipment important to safety is required to remain functional, but that the temperat ure conditions resulting from external events, such as tornados, are addressed external to electric equipment qualification programs, consistent with the provisions of 10 CFR 50.49(c) and 50.49(e)(1).

We request this letter and any subsequent communications be placed into the public Agencywide Documents Access and Management System. We look forward to opportunities to discuss this issue with you at your convenience.

Respectfully,

William A. Horin Partner, Winston & Strawn LLP Counsel to NUGEQ

cc (via email):

R. Kopriva, R-IV/DORS/EB1 Ron.Kopriva@nrc.gov J. Braisted, R-IV/DORS/EB1 Jonathan.Braisted@nrc.gov M. Gray, R-I/DORS/EB1 Mel.Gray@nrc.gov Glenn Dentel, R-I/DORS/EB2 Glenn.Dentel@nrc.gov James Baptist, R-II/DRS/EB1 James.Baptist@nrc.gov Karla Stoedter, R-III/DRS/EB2 Karla.Stoedter@nrc.gov Richard Skokowski, R-III/DRS/EB3 Richard.Skokowski@nrc.gov

Vincent G. Gaddy September 27, 2022 Page 4

Nicholas Taylor, R-IV/DORS/EB2 Nick.Taylor@nrc.gov Matt McConnell, NRR/ELTB/DEX Matthew.McConnell@nrc.gov