ML15289A494

Request for Additional Information Related to Exemption Request from 10 CFR 50.55a, Codes and Standards, Paragraph (h)(2), Protection Systems.

ML15289A494
Person / Time
Site:	Byron, Braidwood
Issue date:	01/20/2016
From:	Joel Wiebe Plant Licensing Branch III
To:	Bryan Hanson Exelon Generation Co, Exelon Nuclear
Joel Wiebe, NRR/DORL
References
CAC MF6079, CAC MF6080, CAC MF6081, CAC MF6082
Download: ML15289A494 (7)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 January 20, 2016 Mr. Bryan C. Hanson Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer (CNO)

Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

BRAIDWOOD STATION, UNITS 1 AND 2, AND BYRON STATION, UNIT NOS. 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO EXEMPTION REQUEST FROM 10 CFR 50.55a, "CODES AND STANDARDS,"

PARAGRAPH (h)(2), "PROTECTION SYSTEMS." (CAC NOS. MF6079, MF6080, MF6081, AND MF6082)

Dear Mr. Hanson:

By letter to the U.S. Nuclear Regulatory Commission (NRC) dated April 6, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15097A123), Exelon Generation Company, LLC (EGC, the licensee) submitted a request pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Part 50.12(a)(2)(ii) for exemption from 10 CFR 50.55a, "Codes and standards, paragraph (h)(2), "Protection Systems, regarding Braidwood Station, Units 1 and 2, and Byron Station, Unit Nos. 1 and 2, Facilities Operating Licenses. The proposed exemption would eliminate the requirement for system level initiation of the main steam line bypass valves isolation per the criteria stated in Institute of Electrical and Electronics Engineers (IEEE), [Standard] Std. 279, Section 4.17, "Manual Initiation." The NRC staff has identified the need for additional information for technical branch review to complete the review of the exemption request.

The NRC staff is reviewing your submittal and has determined that the request for additional information (RAI) is required to complete the review. Following the original submittal of draft RAls on October 14, 2015, followed-up by a clarification teleconference between the NRC and EGC on November 23, 2015, the requested information is included in the enclosure to this letter. In an email sent to Mr. Joseph Bauer of your staff on December 31, 2015, the NRC stated these RAls will be docketed to the Byron/Braidwood Stations. Additionally, Mr. Bauer was informed the NRC is requesting for EGC to respond to these RAls no later than January 29, 2016. This will support the staff's ongoing review of the proposed exemption request.

The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources.

B. Hanson If circumstances result in the need to revise the requested response date, please contact Russell Haskell at (301) 415-1129, or by email at Russell.Haskell@nrc.gov.

incerely,~ ) ~~

, ~ .-&

oel S. Wiebe, Senior Project Manager Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-456, STN 50-457, STN 50-454 and STN 50-455

Enclosure:

Request for Additional Information cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION REQUEST FOR EXEMPTION FROM 10 CFR 50.55a, "CODES AND STANDARDS,"

PARAGRAPH (h)(2), "PROTECTION SYSTEMS."

BRAIDWOOD STATION, UNITS 1 AND 2. AND BYRON STATION, UNIT NOS. 1 AND 2 (CAC NOS. MF6079, MF6080, MF6081, AND MF6082)

By letter dated April 6, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15097A123), Exelon Generation Company, LLC (the licensee) submitted a request pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Part 50.12(a)(2)(ii) for exemption from 10 CFR 50.55a, "Codes and standards," paragraph (h)(2),

"Protection Systems," regarding Braidwood Station, Units 1 and 2, and Byron Station, Unit Nos.

1 and 2, Facilities Operating Licenses. The proposed exemption would eliminate the requirement for manual system level initiation of the main steam line bypass valves isolation per the criteria stated in the Institute of Electrical and Electronics Engineers (IEEE) [Standard] Std.

279, Section 4.17, "Manual Initiation." The technical review branch for instrumentation and control has identified the need for additional information to complete the review of the exemption request:

1. As the request states, the exemption would eliminate the requirement to meet the criteria stated in IEEE Std. 279, Section 4.17, "Manual Initiation," only for the main steam isolation valve (MSIV) bypass valves manual isolation function. However, the criterion of Section 4.17 consists of three statements. The first concerns the system level initiation; the second the single-failure; and the third the manual initiation function depending on a minimum of equipment. The questions below will address these three sections by addressing the Regulatory Position of the NRC staff in Regulatory Guide (RG)1.62, Manual Initiation of Protective Actions (October 1973).

a. Regulatory Position C.2, states: "Manual initiation of a protective action at the system level should perform all actions performed by the automatic initiation ... " and provides examples of those types of actions.

Provide a list of all actions that are done at the automatic initiation, how they are done, and how they are confirmed, at the manual level initiation of the MSIV and bypass valves.

b. P.5 of the exemption request states: "the existing individual MSIV bypass valves manual control switches are single train switches such that a single failure of a switch could prevent the manual initiation of the protective action (i.e., prevent closure of the MSIV bypass valve)."

Provide justification for the current configuration not meeting the single-failure criterion 4.2, of IEEE Std. 279.

Enclosure

i. Has there been an analysis done to determine the effects of one or more MSIV bypass valves failed open?

ii. Explain how the containment isolation function is single failure proof and the current configuration is acceptable.

c. Regulatory Position C.4 also states: "The amount of equipment common to both manual and automatic initiation should be kept to a minimum."

Describe the equipment and circuitry, or portions thereof, which are common to automatic and manual initiation, whether it be component or system level initiation.

2. Consistent with RG 1.62; "Manual Initiation of Protective Actions," (dated October 1973),

Regulatory Position 6 states, "Manual initiation of protective action at the system level should be so designed that once initiated, it will go to completion as required in Section 4.16 of IEEE Std. 279-1971."

a. Explain the additional actions involved with the MSIV bypass valve that would be necessary to be equivalent to the automatic initiation described above to insure it has gone to completion.

b. Describe the type of switch, the positions available, any spring-return actions, and what is required to manipulate it. Also include necessary indications that confirm the actions have taken place.

3. Review by the NRC staff of manual controls as required by IEEE Std. 279-1971, Clause 4.17, includes confirmation that the characteristics of the controls allow plant operators to take appropriate manual actions during plant conditions under which they would be necessary.

Is there a time limitation to manipulate both sets of switches? Is this identified by procedure and part of a drill or exercise?

4. Page 3 of the Request for Exemption states that the MSIV bypass valves are also containment isolation valves.

a. Since the main steam line manual isolation switches do not operate the bypass valves, do the group-level Containment Isolation switches operate the bypass valves?

b. Was the original intent of the MSIV bypass valve manual control switches to be used for testing only?

5. Regulatory Position C.3 of RG 1.62 includes: "The switches for manual initiation of protective actions at the system level should be located in the control room and be easily accessible to the operator so that action can be taken in an expeditious manner."

Explain, or illustrate by figure preferably, the relative physical location of switches and indicators used for the system level main steam line manual isolation and the same for individual MSIV bypass valves switches and indicators.

6. The exemption request states, in part, that the description of the modification to eliminate the non-conformance with the requirements of IEEE Std. 279 and will be "costly."

Describe the major modifications to the systems, structures and components as well as the impacts on the schedule and operation of the Byron/Braidwood Station units.

7. Per discussion in the Background Section of the exemption request, the conclusion is made that the TS are consistent with actual plant configuration from inspection of Table 3.3.2-1, Function 4, of the technical specification (TS) and the bases. However, the NRC staff noted three inconsistencies between the TS and actual plant configuration, as described below.

a. Based on a review of the current TS Table 3.3.2-1, Function 4.a, "Manual Initiation,"

Modes 2 and 3 have an associated Note C which states, "Except when all Main Steam Isolation Valves (MSIVs) are closed." While the MSIV bypass valves are unmentioned in the note, it does not preclude them from this TS since the main steam isolation function is accomplished by closure of the MSIVs and their associated bypass valves as discussed in Section 11.3 of the exemption request. Further, when the bypass valves are open and the MSIVs are closed during startup, you need to have manual initiation capability of the bypass valves. Therefore, actual plant configuration is not consistent with the TS.

b. Related to request for additional information (RAl)-1 a, Note C for Function 4.a, "Manual Initiation" applies to Modes 2 and 3. It does not apply to Mode 1. Since the main steam isolation function is accomplished by closure of the MSIVs and their associated bypass valves as discussed in Section 11.3 of the exemption request, manual initiation of the bypass valves are required in rviode 1. Therefore, actual plant configuration is not consistent with the TS.

c. As discussed in RAl-1a and RAl-1b, Function 4.a, applies to the bypass valves.

Function 4.a. requires two channels to be operable to meet the limiting condition for operation. However, as discussed in the exemption request, the manual initiation of the bypass valves are single-train; therefore, actual plant configuration is not consistent with the TS.

Explain why additional TS revisions are not necessary given the actual plant configuration.

8. Per Section 11.3 of the exemption request, it is noted that individual MSIV bypass valve switches are single train switches. Per 10 CFR Appendix A, General Design Criterion 21, Protection system reliability and testability. The criterion states, in part, that (1 ): "no single failure results in the loss of a protection function."

Since the MSIV bypass valves are included in protection systems, discuss how GDC 21 is met since the manual switches are single train.

9. Per Section 11.2 of the exemption request, it is noted that the MSIV bypass valves are also containment isolation valves. TS Table 3.3.2-1, Function 3, governs the containment isolation function. From a review of this TS, there is no indication that manual initiation only applies to the MSIVs and not their associated bypass valves.

Provide justification why it is not necessary to update the TSs to reflect the lack of a system level MSIV bypass valve switch.

10. When determining the limiting single-failure for the safety analyses; Was it assumed that the MSIV bypass valves had a manual system level switch in addition to the manual single operation switch? If this was assumed, provide additional justification of the limiting single-failure determination.

11. Is there a single failure that would cause all four MSIV bypass valves manual initiation function to fail? If so, provide justification this is an acceptable condition with respect to the applicable safety analyses.

12. Elaborate on what components are credited during the steam generator tube rupture event if a MSIV bypass valve fails to close on the faulted steam generator. Are the credited components safety-related or nonsafety-related?

ML15289A494 OFFICE DORL/LP LI 11-2/PM DORL/LPL! 11-2/LA DORL/LPL! 11-2/BC(A) DORL/LPL! 11-2/PM NAME RHaskell SRohrer JPoole JWiebe DATE 1/11/2016 1/14/2016 1/15/2016 1/20/2016