ML17163A367
| ML17163A367 | |
| Person / Time | |
|---|---|
| Site: | Technical Specifications Task Force |
| Issue date: | 06/20/2017 |
| From: | Jennifer Whitman NRC/NRR/DSS/STSB |
| To: | Technical Specifications Task Force |
| Honcharik M, DSS/STSB 301-415-1774 | |
| References | |
| CAC MF7622 | |
| Download: ML17163A367 (17) | |
Text
June 20, 2017 Technical Specifications Task Force 11921 Rockville Pike, Suite 100 Rockville, MD 20852
SUBJECT:
DRAFT SAFETY EVALUATION OF TECHNICAL SPECIFICATIONS TASK FORCE TRAVELER TSTF-546, REVISION 0, "REVISE APRM CHANNEL ADJUSTMENT SURVEILLANCE REQUIREMENT" (CAC NO. MF7622)
Dear Members of the Technical Specifications Task Force:
By letter dated April 21, 2016 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML16112A208), the Technical Specifications Task Force (TSTF) submitted to the U.S. Nuclear Regulatory Commission (NRC) for review and approval traveler TSTF-546, Revision 0, Revise APRM [Average Power Range Monitor] Channel Adjustment Surveillance Requirement. The NRC staffs draft safety evaluation (SE) of the traveler and a draft model SE are enclosed.
Thirty calendar days are provided to you to comment on any factual errors or clarity concerns contained in the enclosed draft SEs. The final SEs will be issued after making any necessary changes. The NRC staff's disposition of your comments on the draft SEs will be discussed in the final SEs. To facilitate the NRC staff's review of your comments, please provide a marked-up copy of the draft SEs showing proposed changes and provide a summary table of the proposed changes.
If you have any questions, please contact Michelle Honcharik at 301-415-1774 or via e-mail at Michelle.Honcharik@nrc.gov.
Sincerely, Jennifer M. Whitman, Acting Chief /RA/
Technical Specifications Branch Division of Safety Systems Office of Nuclear Reactor Regulation Project No. 753
Enclosures:
- 1. NRC staffs draft Safety Evaluation of the traveler
- 2. Draft model Safety Evaluation cc: See next page
Technical Specifications Task Force Project No. 753 cc:
Technical Specifications Task Force c/o EXCEL Services Corporation 11921 Rockville Pike, Suite 100 Rockville, MD 20852 Attention: Brian D. Mann E-mail: brian.mann@excelservices.com James R. Morris Diablo Canyon Power Plant Building 104/5/21A P.O. Box 56 Avila Beach, CA 93424 E-mail: james.morris@pge.com Lisa L. Williams Energy Northwest Columbia Generating Station PO Box 968 Mail Drop PE20 Richland, WA 99352-0968 E-mail: llwilliams@energy-northwest.com Otto W. Gustafson Entergy Nuclear Operations, Inc.
Palisades Nuclear Power Plant 27780 Blue Star Memorial Highway Covert, MI 49043 E-mail: ogustaf@entergy.com Jordan L. Vaughan Duke Energy EC2ZF / P.O. Box 1006 Charlotte, NC 28202 Email: jordan.vaughan@duke-energy.com Jason P. Redd Southern Nuclear Operating Company 42 Inverness Center Parkway Bin B234 Birmingham, AL 35242-4809 E-mail: jpredd@southernco.com
Package: Cover letter and Draft traveler SE: ML17135A188, draft Model SE: ML17135A189;
- concurrence from internal memo (ML17040A085)
- concurred via e-mail NRR-106 OFFICE DSS/STSB DSS/EICB*
DSS/SRXB**
DORL/BC**
NAME MHoncharik MWaters EOesterle DWrona DATE 5/15/2017 3/9/2017 5/17/2017 5/25/2017 OFFICE OGC (NLO)
DSS/STSB DSS/STSB**
NAME JWachutka MHoncharik (TTjader for)
JMWhitman DATE 6/9/17 06/20/17 06/20/17 DRAFT SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION 1
TECHNICAL SPECIFICATIONS TASK FORCE TRAVELER 2
TSTF-546, REVISION 0, 3
REVISE APRM CHANNEL ADJUSTMENT SURVEILLANCE REQUIREMENT 4
5 6
1.0 INTRODUCTION
7 8
By letter dated April 21, 2016 (Agencywide Documents Access and Management System 9
(ADAMS) Accession No. ML16112A208), the Technical Specifications (TS) Task Force (TSTF) 10 submitted Traveler TSTF-546, Revise APRM [Average Power Range Monitor] Channel 11 Adjustment Surveillance Requirement [SR], Revision 0, for U.S. Nuclear Regulatory 12 Commission (NRC) review and approval. By letter dated February 2, 2017 (ADAMS Accession 13 No. ML17033A264), the TSTF submitted a response to the NRC staffs request for additional 14 information (RAI). The RAI response did not result in any changes to TSTF-546.
15 16 Traveler TSTF-546 proposes changes to the Standard Technical Specifications (STS) and 17 Bases for boiling water reactor (BWR) designs BWR/4 and BWR/6.1 The changes would be 18 incorporated into future revisions of NUREG-1433, Volumes 1 and 2, and NUREG-1434, 19 Volumes 1 and 2. NUREG-1433 is based on the BWR/4 plant design, and is representative of 20 the BWR/2, BWR/3, and, in some cases, BWR/5 designs. NUREG-1434 is based on the 21 BWR/6 plant design, and is representative of, in many cases, the BWR/5 design.
22 23 The proposed changes would revise SR 3.3.1.1.2 in NUREGs-1433 and -1434 to only require 24 adjustment of the APRM channels if the calculated power exceeds the APRM output by more 25 than 2 percent rated thermal power (RTP).
26 27 Throughout this safety evaluation (SE), items that are enclosed in square brackets signify 28 plant-specific nomenclature or values. Individual licensees would furnish site-specific 29 nomenclature or values for bracketed items when submitting a license amendment request 30 (LAR) to adopt the changes described in this SE.
31 32
2.0 REGULATORY EVALUATION
33 34 2.1 SYSTEM DESCRIPTION 35 36 The APRMs monitor neutron flux within the core to provide an indication of core power. As 37 stated in the STS Bases, the APRM channels receive input signals from the local power range 38 1 U.S. Nuclear Regulatory Commission, Standard Technical Specifications, General Electric BWR/4 Plants, NUREG-1433, Vol. 1, Specifications, Rev. 4.0, April 2012, ADAMS Accession No. ML12104A192.
U.S. Nuclear Regulatory Commission, Standard Technical Specifications, General Electric BWR/4 Plants, NUREG-1433, Vol. 2, Bases, Rev. 4.0, April 2012, ADAMS Accession No. ML12104A193.
U.S. Nuclear Regulatory Commission, Standard Technical Specifications, General Electric BWR/6 Plants, NUREG-1434, Vol. 1, Specifications, Rev. 4.0, April 2012, ADAMS Accession No. ML12104A195.
U.S. Nuclear Regulatory Commission, Standard Technical Specifications, General Electric BWR/6 Plants, NUREG-1434, Vol. 2, Bases, Rev. 4.0, April 2012, ADAMS Accession No. ML12104A196.
monitors (LPRM) within the reactor core to provide an indication of the power distribution and 1
local power changes. The APRM channels average these LPRM signals to provide a 2
continuous indication of average reactor power from a few percent to greater than RTP.
3 4
The APRM system is a safety-related system with two purposes. One purpose is to monitor the 5
core thermal power level. The other purpose is to provide reactor scram and control rod block 6
signals to preserve the fuel cladding integrity. The APRM system consists of a number of 7
APRM channels that each receive input signals from LPRMs located in the reactor core. The 8
APRM channels average the LPRM inputs and because the LPRMs assigned to specific APRM 9
channels are located in diverse axial and radial locations throughout the reactor core, each 10 APRM provides a continuous indication of average reactor power. A gain adjustment can be 11 made to each ARPM channel output allowing it to be calibrated to the calculated core thermal 12 power. The typical allowable absolute difference between calculated core thermal power and 13 the APRM channel output is 2 percent.
14 15 Both analog and digital neutron monitoring systems (NMS) are installed in BWRs and have 16 different APRM system designs. Additionally, there are several different methodologies for 17 addressing BWR instability protection including: Option I-D, Option II, Enhanced Option I-18 A (E1A), Option III, and Detect and Suppress Solution-Confirmation Density (DSS-CD) and the 19 automatic backup stability protection (ABSP) for DSS-CD. The APRMs only provide input for 20 Option I-D, Option II, Enhanced Option I-A, and the ABSP for DSS-CD.
21 22 A typical analog NMS has two groups of channels with three APRM inputs to each reactor 23 protection system (RPS) trip system. Three channels per group allow one channel in each 24 group to be bypassed because any one channel trip signal in each system can cause the 25 associated trip system to be actuated. Power Range Monitor Flow Biased Simulated Thermal 26 Power - High and the APRM Fixed Neutron Flux - High functions, four channels, with two 27 channels in each trip system, are typically required to be operable by Limiting Condition for 28 Operation (LCO) 3.3.1.1 to ensure that no single instrument failure will preclude a trip of the 29 APRM system on a valid signal. If one or more required channels are inoperable, Condition A 30 requires the channel or trip system be placed in the tripped condition within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. If one or 31 more functions with one or more required channels are inoperable in both RPS trip systems, 32 Condition B requires that the channel(s) or trip system(s) be placed in the tripped condition 33 within six hours.
34 35 A typical digital NMS is divided into four APRM channels and four 2-out-of-4 voter channels with 36 each channel providing input to each of the four 2-out-of-4 voter channels. The four voter 37 channels are divided into two groups of two each; each group of two voter channels provides 38 input to one RPS trip system. One APRM channel is allowed to be bypassed, but no voter 39 channels are allowed to be bypassed. A trip from any one APRM channel that is not bypassed 40 will result in a "half-trip" in all four of the voter channels, but no trip inputs to either RPS trip 41 system. A trip of any two channels of APRM flow biased or neutron flux trip that are not 42 bypassed will result in a full trip in each of the four voter channels, which in turn results in two 43 trip inputs to each RPS trip system logic channel. To ensure that no single instrument failure 44 will preclude a trip on a valid signal for the APRM Flow Biased Simulated Thermal Power - High 45 and the APRM Fixed Neutron Flux - High functions, three of the four APRM channels and all 46 four voter channels are typically required to be operable by TS LCO 3.3.1.1. If one or more 47 required channels are inoperable, Condition A requires the channel be placed in the tripped 48 condition within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
49 50 51
2.2 PROPOSED CHANGE
S TO THE STS 1
2 The proposed changes would revise SR 3.3.1.1.2, which is associated with LCO 3.3.1.1A, 3
Reactor Protection System (RPS) Instrumentation (Without Setpoint Control Program) and 4
LCO 3.3.1.1B, Reactor Protection System (RPS) Instrumentation (With Setpoint Control 5
Program).
6 7
SR 3.3.1.1.2 currently states:
8 9
Verify the absolute difference between the average power range 10 monitor (APRM) channels and the calculated power is < 2% RTP 11
[plus any gain adjustment required by LCO 3.2.4, Average Power 12 Range Monitor (APRM) Setpoints] while operating at > 25% RTP 13 14 The proposed SR 3.3.1.1.2 would state:
15 16 Compare the average power range monitor (APRM) channels to 17 the calculated power. Adjust the APRM channels if the calculated 18 power exceeds the APRM output by more than 2% RTP while 19 operating at 25% RTP 20 21 Corresponding changes are proposed to the STS Bases. A summary of the revised STS Bases 22 and the NRC staffs evaluation of the revised Bases are provided in an attachment to this SE.
23 24 2.3 APPLICABLE REGULATORY REQUIREMENTS AND GUIDANCE 25 26 Section IV, The Commission Policy, of the Final Policy Statement on Technical Specifications 27 Improvements for Nuclear Power Reactors (58 Federal Register 39132), dated July 22, 1993, 28 states in part:
29 30 The purpose of Technical Specifications is to impose those 31 conditions or limitations upon reactor operation necessary to 32 obviate the possibility of an abnormal situation or event giving rise 33 to an immediate threat to the public health and safety by 34 identifying those features that are of controlling importance to 35 safety and establishing on them certain conditions of operation 36 which cannot be changed without prior Commission approval.
37 38
[T]he Commission will also entertain requests to adopt portions 39 of the improved STS [(e.g., TSTF-546)], even if the licensee does 40 not adopt all STS improvements.
41 42 The Commission encourages all licensees who submit 43 Technical Specification related submittals based on this Policy 44 Statement to emphasize human factors principles.
45 46 In accordance with this Policy Statement, improved STS have 47 been developed and will be maintained for [BWR designs]. The 48 Commission encourages licensees to use the improved STS as 49 the basis for plant-specific Technical Specifications.
50
[I]t is the Commission intent that the wording and Bases of the 1
improved STS be used to the extent practicable.
2 3
As described in the Commissions Final Policy Statement on Technical Specifications 4
Improvements for Nuclear Power Reactors, recommendations were made by NRC and industry 5
task groups for new STS that include greater emphasis on human factors principles in order to 6
add clarity and understanding to the text of the STS, and provide improvements to the Bases of 7
STS, which provides the purpose for each requirement in the specification. Improved vendor-8 specific STS were developed and issued by the NRC in September 1992.
9 10 The regulation at Title 10 of the Code of Federal Regulations (10 CFR) Section 50.36(a)(1) 11 requires an applicant for an operating license to include in the application proposed TS in 12 accordance with the requirements of 10 CFR 50.36. The applicant must include in the 13 application a summary statement of the bases or reasons for such specifications, other than 14 those covering administrative controls. However, per 10 CFR 50.36(a)(1), these technical 15 specification bases shall not become part of the technical specifications.
16 17 Additionally, 10 CFR 50.36(b) requires:
18 19 Each license authorizing operation of a utilization facility will 20 include technical specifications. The technical specifications will 21 be derived from the analyses and evaluation included in the safety 22 analysis report, and amendments thereto, submitted pursuant to 23
[10 CFR] 50.34 [Contents of applications; technical information].
24 The Commission may include such additional technical 25 specifications as the Commission finds appropriate.
26 27 The categories of items required to be in the TSs are provided in 10 CFR 50.36(c). As required 28 by 10 CFR 50.36(c)(2)(i), the TSs will include LCOs, which are the lowest functional capability 29 or performance levels of equipment required for safe operation of the facility. Per 10 CFR 30 50.36(c)(2)(i), when an LCO of a nuclear reactor is not met, the licensee shall shut down the 31 reactor or follow any remedial action permitted by the TSs until the condition can be met.
32 33 The regulation at 10 CFR 50.36(c)(3) requires TSs to include items in the category of SRs, 34 which are requirements relating to test, calibration, or inspection to assure that the necessary 35 quality of systems and components is maintained, that facility operation will be within safety 36 limits, and that the LCOs will be met.
37 38 Per 10 CFR 50.90, whenever a holder of a license desires to amend the license, application for 39 an amendment must be filed with the Commission, fully describing the changes desired, and 40 following as far as applicable, the form prescribed for original applications.
41 42 Per 10 CFR 50.92(a), in determining whether an amendment to a license will be issued to the 43 applicant, the Commission will be guided by the considerations which govern the issuance of 44 initial licenses to the extent applicable and appropriate.
45 46 The NRC staffs guidance for the review of TSs is in Chapter 16, Technical Specifications, of 47 NUREG-0800, Revision 3, Standard Review Plan for the Review of Safety Analysis Reports for 48 Nuclear Power Plants (SRP), dated March 2010 (ADAMS Accession No. ML100351425). As 49 described therein, as part of the regulatory standardization effort, the NRC staff has prepared 50 STS for each of the light-water reactor nuclear designs.
51
3.0 TECHNICAL EVALUATION
1 2
The existing TS SR 3.3.1.1.2 requires verification that the absolute difference between the 3
APRM channels and the calculated power is 2 percent RTP [plus any gain adjustment 4
required by LCO 3.2.4, Average Power Range Monitor (APRM) Setpoints] while operating at 5
> 25 percent RTP. If the absolute difference is greater than 2 percent, the APRM channel is 6
declared inoperable. An acceptable way to restore operability is to adjust the gain for the APRM 7
channel to restore the absolute difference to 2 percent. If the APRM channel is reading higher 8
than the calculated thermal power, this adjustment would be non-conservative with respect to 9
the RPS trip setpoint. If the APRM channel is reading lower than the calculated thermal power, 10 this adjustment would be conservative with respect to the RPS trip setpoint.
11 12 The proposed change would require adjustment of the APRM channel only if the APRM is 13 non-conservative with respect to calculated thermal power (i.e., reading lower than calculated 14 thermal power). In this situation, the adjustment of the APRM channel is permitted, but not 15 required, if the APRM channel is conservative with respect to the calculated thermal power.
16 17 The NRC staff requested additional information on whether this proposed change would affect 18 the effectiveness of any of the stability solutions for BWRs. In the response dated February 2, 19 2017, the TSTF stated that stability solutions (e.g., Option III and DSS-CD) that rely on the 20 LPRMs are not affected by this change. For stability solutions that rely on the APRMs for the 21 main licensing basis protection (e.g., Option I-D, Option II, Enhanced Option I-A, and the ABSP 22 for DSS-CD), this change would result in earlier (i.e., conservative) RPS actuation. The NRC 23 staff reviewed this response and determined that it is not clear that a high APRM signal is 24 always conservative for the ABSP. However, this backup solution is only used when the normal 25 stability protection is inoperable and its use is limited to 120 days. Therefore, the proposed 26 change would negligibly affect the ABSP and is acceptable to the NRC staff.
27 28 The regulation at 10 CFR 50.36(c)(3) requires that the TS contain SRs, which are requirements 29 relating to test, calibration, or inspection to assure that the necessary quality of systems and 30 components is maintained, that facility operation will be within safety limits, and that the limiting 31 conditions for operation will be met. The NRC staff reviewed the changes proposed to SR 32 3.3.1.1.2 as described in this SE. The NRC staff determined that the SR, as modified, 33 continues to provide appropriate controls and acceptance criteria for adjustment of the APRMs 34 to ensure that the APRMs appropriately reflect actual reactor power. The NRC staff determined 35 that the SR continues to verify the operability of the APRMs and provide assurance that the 36 necessary quality of systems and components is maintained.
37 38
4.0 CONCLUSION
39 40 The NRC staff reviewed traveler TSTF-546, Revision 0, which proposed changes to 41 NUREG-1433, Volumes 1 (STS) and 2 (Bases), and NUREG-1434, Volumes 1 (STS) and 42 2 (Bases). The NRC staff determined that the proposed changes to the STS meet the 43 standards for TS in 10 CFR 50.36(b). The proposed changes to the SR assure that the 44 necessary quality of systems and components is maintained, that facility operation will be within 45 safety limits, and that the LCOs will be met, and satisfy 10 CFR 50.36(c)(3). Additionally, the 46 changes to the STS were reviewed for technical clarity and consistency with customary 47 terminology and format in accordance with SRP Chapter 16.
48 49 The proposed Bases, which will be added to future revisions to NUREG-1433, Volume 2, and 50 NUREG-1434, Volume 2, satisfy the Commissions Policy Statement by addressing the 51 questions specified in the policy statement, and cite references to appropriate licensing 1
documentation to support the Bases.
2 3
Technical contacts:
Jennifer M. Whitman, NRR/DSS/SRXB 4
Gursharan Singh, NRR/DE/EICB 5
6
Attachment:
Basis for Accepting the Proposed Changes to the Standard Technical 7
Specification Bases, Volume 2 of NUREGs-1433 and -1434 8
9 Date: June 20, 2017 10 11 12 13 14
ATTACHMENT 1
2 BASIS FOR ACCEPTING THE PROPOSED CHANGES TO THE STANDARD TECHNICAL 3
SPECIFICATION BASES, VOLUME 2 OF NUREGS-1433 AND -1434 4
5 6
1.0 INTRODUCTION
7 8
Traveler Technical Specifications (TS) Task Force (TSTF) TSTF-546, Revise APRM [Average 9
Power Range Monitor] Channel Adjustment Surveillance Requirement [SR], Revision 0, 10 proposes changes to the Standard Technical Specifications (STS) and Bases for boiling water 11 reactor (BWR) designs BWR/4 and BWR/6.2 The changes would be incorporated into future 12 revisions of NUREG-1433, Volumes 1 and 2, and NUREG-1434, Volumes 1 and 2.
13 NUREG-1433 is based on the BWR/4 plant design, and is representative of the BWR/2, BWR/3, 14 and, in some cases, BWR/5 designs. NUREG-1434 is based on the BWR/6 plant design, and is 15 representative of, in many cases, the BWR/5 design.
16 17 The proposed changes would revise SR 3.3.1.1.2 in NUREGs-1433 and -1434 to only require 18 adjustment of the APRM channels if the calculated power exceeds the APRM output by more 19 than 2 percent rated thermal power (RTP). The Bases for SR 3.3.1.1.2 in NUREGs-1433 and -
20 1434 would also be revised. A summary of the revised Bases and the U.S. Nuclear Regulatory 21 Commission (NRC) staffs evaluation of the revised Bases are presented in this attachment.
22 23
2.0 REGULATORY EVALUATION
24 25 2.1 Applicable Regulations and Guidance 26 27 The regulation at Title 10 of the Code of Federal Regulations (10 CFR) Section 50.36(a)(1) 28 states that each applicant for a license authorizing operation of a production or utilization facility 29 shall include in his application proposed technical specifications in accordance with the 30 requirements of this section. A summary statement of the bases or reasons for such 31 specifications, other than those covering administrative controls, shall also be included in the 32 application, but shall not become part of the technical specifications.
33 34 In its Final Policy Statement on Technical Specifications Improvements for Nuclear Power 35 Reactors, dated July 22, 1993 (58 Federal Register 39132), the Commission presented its 36 policy on the scope and purpose of the TS. The Commission explained how implementation of 37 the policy statement through implementation of the improved STS is expected to produce an 38 improvement in the safety of nuclear power plants through the use of more operator-oriented 39 2 U.S. Nuclear Regulatory Commission, Standard Technical Specifications, General Electric BWR/4 Plants, NUREG-1433, Vol. 1, Specifications, Rev. 4.0, April 2012, ADAMS Accession No. ML12104A192.
U.S. Nuclear Regulatory Commission, Standard Technical Specifications, General Electric BWR/4 Plants, NUREG-1433, Vol. 2, Bases, Rev. 4.0, April 2012, ADAMS Accession No. ML12104A193.
U.S. Nuclear Regulatory Commission, Standard Technical Specifications, General Electric BWR/6 Plants, NUREG-1434, Vol. 1, Specifications, Rev. 4.0, April 2012, ADAMS Accession No. ML12104A195.
U.S. Nuclear Regulatory Commission, Standard Technical Specifications, General Electric BWR/6 Plants, NUREG-1434, Vol. 2, Bases, Rev. 4.0, April 2012, ADAMS Accession No. ML12104A196.
TS, improved TS Bases, reduced action-statement-induced plant transients, and more efficient 1
use of NRC and industry resources.
2 3
The Final Policy Statement provides the following description of the scope and the purpose of 4
the Technical Specification Bases:
5 6
Appropriate Surveillance Requirements and Actions should be 7
retained for each LCO [limiting condition for operation] which 8
remains or is included in the Technical Specifications. Each LCO, 9
Action, and Surveillance Requirement should have supporting 10 Bases. The Bases should at a minimum address the following 11 questions and cite references to appropriate licensing 12 documentation (e.g., FSAR, Topical Report) to support the Bases.
13 14
- 1. What is the justification for the Technical Specification, i.e., which 15 Policy Statement criterion requires it to be in the Technical 16 Specifications?
17 18
- 2. What are the Bases for each LCO, i.e., why was it determined to 19 be the lowest functional capability or performance level for the 20 system or component in question necessary for safe operation of 21 the facility and, what are the reasons for the Applicability of the 22 LCO?
23 24
- 3. What are the Bases for each Action, i.e., why should this remedial 25 action be taken if the associated LCO cannot be met; how does 26 this Action relate to other Actions associated with the LCO; and 27 what justifies continued operation of the system or component at 28 the reduced state from the state specified in the LCO for the 29 allowed time period?
30 31
- 4. What are the Bases for each Safety Limit?
32 33
- 5. What are the Bases for each Surveillance Requirement and 34 Surveillance Frequency; i.e., what specific functional requirement 35 is the surveillance designed to verify? Why is this surveillance 36 necessary at the specified frequency to assure that the system or 37 component function is maintained, that facility operation will be 38 within the Safety Limits, and that the LCO will be met?
39 40 Note: In answering these questions the Bases for each number 41 (e.g., Allowable Value, Response Time, Completion Time, 42 Surveillance Frequency), state, condition, and definition (e.g.,
43 operability) should be clearly specified. As an example, a number 44 might be based on engineering judgment, past experience, or 45 PSA [probabilistic safety assessment] insights; but this should be 46 clearly stated.
47 48 The NRC staff used the guidance contained in the Final Policy Statement during its evaluation 49 of the proposed changes to the Bases.
50 51 2.2 Description of Changes 1
2 Volumes 2 of NUREGs-1433 and -1434 contain the Bases for each Safety Limit and each LCO 3
contained in Volumes 1 of NUREGs-1433 and -1434. The Bases for each LCO are organized 4
into the following sections:
5 6
Background; 7
Applicable Safety Analyses, LCO, and Applicability; 8
Actions; 9
Surveillance Requirements; and 10 References.
11 12 The Bases for SR 3.3.1.1.2 in NUREGs-1433 and -1434 are proposed to be revised. The 13 following discussion provides a summary of the revised Bases, followed by the NRC staffs 14 evaluation of the revised Bases.
15 16
3.0 TECHNICAL EVALUATION
17 18 The Bases for SR 3.3.1.1.2 are proposed to be revised by the insertion of a description of the 19 revised SR 3.3.1.1.2. The revised Bases state that the APRMs are adjusted to the reactor 20 power calculated from a heat balance if the heat balance calculated reactor power exceeds the 21 APRM channel output by more than 2 percent RTP. The Bases explain that, if the APRM 22 channel cannot be adjusted to within this tolerance, the channel is declared inoperable. The 23 revised SR 3.3.1.1.2 does not preclude adjusting the APRMs if the reactor power is less than 24 the APRM indication, but this adjustment is not required for APRM operability.
25 26 The NRC staff reviewed the revised Bases and determined that they adequately provide an 27 appropriate description of the SR, the conditions under which an APRM channel is considered 28 inoperable, and the basis for the SR.
29 30
4.0 CONCLUSION
31 32 The NRC staff determined that the proposed TS Bases changes are consistent with the 33 proposed TS changes and provide an explanation and supporting information for the SR.
34 Therefore, the NRC staff determined that the revised Bases are consistent with the 35 Commission's Final Policy Statement on Technical Specifications Improvements for Nuclear 36 Power Reactors, dated July 22, 1993 (58 Federal Register 39132).
37
DRAFT MODEL SAFETY EVALUATION 1
BY THE OFFICE OF NUCLEAR REACTOR REGULATION 2
TECHNICAL SPECIFICATIONS TASK FORCE TRAVELER 3
TSTF-546, REVISION 0, 4
REVISE APRM CHANNEL ADJUSTMENT SURVEILLANCE REQUIREMENT 5
6 7
1.0 INTRODUCTION
8 9
By application dated [enter date] (Agencywide Documents Access and Management System 10 (ADAMS) Accession No. [MLXXXXXXXXX]), [name of licensee] (the licensee) requested 11 changes to the technical specifications (TSs) for [name of facility]. Specifically, the licensee 12 requested changes to the TSs to adopt Technical Specifications Task Force (TSTF) traveler 13 TSTF-546, Revision 0, Revise APRM [Average Power Range Monitor] Channel Adjustment 14 Surveillance Requirement, dated April 21, 2016 (ADAMS Accession No. ML16112A208). The 15 NRC approved the traveler on Month, Day, 2017 (ADAMS Accession No. MLXXXX).
16 17 The proposed changes would revise a surveillance requirement (SR) to only require adjustment 18 of the APRM channels if the calculated power exceeds the APRM output by more than 19 2 percent rated thermal power (RTP).
20 21
2.0 REGULATORY EVALUATION
22 23 2.1 SYSTEM DESCRIPTION 24 25 The APRMs monitor neutron flux within the core to provide an indication of core power. The 26 APRM channels receive input signals from the local power range monitors (LPRM) within the 27 reactor core to provide an indication of the power distribution and local power changes. The 28 APRM channels average these LPRM signals to provide a continuous indication of average 29 reactor power from a few percent to greater than RTP.
30 31 The APRM system is a safety-related system with two purposes. One purpose is to monitor the 32 core thermal power level. The other purpose is to provide reactor scram and control rod block 33 signals to preserve the fuel cladding integrity. The APRM system consists of a number of 34 APRM channels that each receive input signals from LPRMs located in the reactor core. The 35 APRM channels average the LPRM inputs and because the LPRMs assigned to specific APRM 36 channels are located in diverse axial and radial locations throughout the reactor core, each 37 APRM provides a continuous indication of average reactor power. A gain adjustment can be 38 made to each ARPM channel output allowing it to be calibrated to the calculated core thermal 39 power. The typical allowable absolute difference between calculated core thermal power and 40 the APRM channel output is 2 percent.
41 42 Both analog and digital neutron monitoring systems (NMS) are installed in BWRs and have 43 different APRM system designs. Additionally, there are several different methodologies for 44 addressing BWR instability protection including: Option I-D, Option II, Enhanced 45 Option I-A (E1A), Option III, and Detect and Suppress Solution-Confirmation Density (DSS-CD) 46 and the automatic backup stability protection (ABSP) for DSS-CD. The APRMs only provide 1
input for Option I-D, Option II, Enhanced Option I-A, and the ABSP for DSS-CD.
2 3
A typical analog NMS has two groups of channels with three APRM inputs to each reactor 4
protection system (RPS) trip system. Three channels per group allow one channel in each 5
group to be bypassed because any one channel trip signal in each system can cause the 6
associated trip system to be actuated. Power Range Monitor Flow Biased Simulated Thermal 7
Power - High and the APRM Fixed Neutron Flux - High functions, four channels, with two 8
channels in each trip system, are typically required to be operable by Limiting Condition for 9
Operation (LCO) 3.3.1.1 to ensure that no single instrument failure will preclude a trip of the 10 APRM system on a valid signal. If one or more required channels are inoperable, Condition A 11 requires the channel or trip system be placed in the tripped condition within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. If one or 12 more functions with one or more required channels are inoperable in both RPS trip systems, 13 Condition B requires that the channel(s) or trip system(s) be placed in the tripped condition 14 within six hours.
15 16 A typical digital NMS is divided into four APRM channels and four 2-out-of-4 voter channels with 17 each channel providing input to each of the four 2-out-of-4 voter channels. The four voter 18 channels are divided into two groups of two each; each group of two voter channels provides 19 input to one RPS trip system. One APRM channel is allowed to be bypassed, but no voter 20 channels are allowed to be bypassed. A trip from any one APRM channel that is not bypassed 21 will result in a half-trip in all four of the voter channels, but no trip inputs to either RPS trip 22 system. A trip of any two channels of APRM flow biased or neutron flux trip that are not 23 bypassed will result in a full trip in each of the four voter channels, which in turn results in two 24 trip inputs to each RPS trip system logic channel. To ensure that no single instrument failure 25 will preclude a trip on a valid signal for the APRM Flow Biased Simulated Thermal Power - High 26 and the APRM Fixed Neutron Flux - High functions, three of the four APRM channels and all 27 four voter channels are typically required to be operable by TS LCO 3.3.1.1. If one or more 28 required channels are inoperable, Condition A requires the channel be placed in the tripped 29 condition within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
30 31 2.2 PROPOSED TECHNICAL SPECIFICATION CHANGES 32 33 The proposed changes would revise SR 3.3.1.1.2, which is associated with LCO 3.3.1.1, 34 Reactor Protection System (RPS) Instrumentation.
35 36 SR 3.3.1.1.2 currently states:
37 38 Verify the absolute difference between the average power range 39 monitor (APRM) channels and the calculated power is 2% RTP 40
[plus any gain adjustment required by LCO 3.2.4, Average Power 41 Range Monitor (APRM) Setpoints] while operating at 25% RTP 42 43 The proposed SR 3.3.1.1.2 would state:
1 2
Compare the average power range monitor (APRM) channels to 3
the calculated power. Adjust the APRM channels if the calculated 4
power exceeds the APRM output by more than 2% RTP while 5
operating at 25% RTP 6
7 2.3 REGULATORY REQUIREMENTS AND GUIDANCE 8
9 The regulation at Title 10 of the Code of Federal Regulations (10 CFR) Section 50.36(a)(1) 10 requires an applicant for an operating license to include in the application proposed TS in 11 accordance with the requirements of 10 CFR 50.36. The applicant must include in the 12 application a summary statement of the bases or reasons for such specifications, other than 13 those covering administrative controls.... However, per 10 CFR 50.36(a)(1), these technical 14 specification bases shall not become part of the technical specifications.
15 16 Additionally, 10 CFR 50.36(b) requires:
17 18 Each license authorizing operation of a utilization facility will 19 include technical specifications. The technical specifications will 20 be derived from the analyses and evaluation included in the safety 21 analysis report, and amendments thereto, submitted pursuant to 22
[10 CFR] 50.34 [Contents of applications; technical information].
23 The Commission may include such additional technical 24 specifications as the Commission finds appropriate.
25 26 The categories of items required to be in the TSs are provided in 10 CFR 50.36(c). As required 27 by 10 CFR 50.36(c)(2)(i), the TSs will include limiting conditions for operation (LCOs), which are 28 the lowest functional capability or performance levels of equipment required for safe operation 29 of the facility. Per 10 CFR 50.36(c)(2)(i), when an LCO of a nuclear reactor is not met, the 30 licensee shall shut down the reactor or follow any remedial action permitted by the TSs until the 31 condition can be met.
32 33 The regulation at 10 CFR 50.36(c)(3) requires TSs to include items in the category of SRs, 34 which are requirements relating to test, calibration, or inspection to assure that the necessary 35 quality of systems and components is maintained, that facility operation will be within safety 36 limits, and that the LCOs will be met.
37 38 The NRC staffs guidance for the review of TSs is in Chapter 16, Technical Specifications, of 39 NUREG-0800, Revision 3, Standard Review Plan for the Review of Safety Analysis Reports for 40 Nuclear Power Plants (SRP), dated March 2010 (ADAMS Accession No. ML100351425).
41 42
3.0 TECHNICAL EVALUATION
43 44 The existing TS SR 3.3.1.1.2 requires verification that the absolute difference between the 45 APRM channels and the calculated power is 2 percent RTP [plus any gain adjustment 46 required by LCO 3.2.4, Average Power Range Monitor (APRM) Setpoints] while operating at 47 25 percent RTP. If the absolute difference is greater than 2 percent, the APRM channel is 48 declared inoperable. An acceptable way to restore operability is to adjust the gain for the APRM 1
channel to restore the absolute difference to 2 percent. If the APRM channel is reading higher 2
than the calculated thermal power, this adjustment would be non-conservative with respect to 3
the RPS trip setpoint. If the APRM channel is reading lower than the calculated thermal power, 4
this adjustment would be conservative with respect to the RPS trip setpoint.
5 6
The proposed change would require adjustment of the APRM channel only if the APRM is 7
non-conservative with respect to calculated thermal power (i.e., reading lower than calculated 8
thermal power). In this situation, the adjustment of the APRM channel is permitted, but not 9
required, if the APRM channel is conservative with respect to the calculated thermal power.
10 11
[NOTE: During the review of the traveler, the NRC staff requested additional information on 12 whether this proposed change would affect the effectiveness of any of the stability solutions for 13 BWRs. In the response dated February 2, 2017, the TSTF stated that stability solutions (e.g.,
14 Option III and DSS-CD) that rely on the LPRMs are not affected by this change. For stability 15 solutions that rely on the APRMs for the main licensing basis protection (e.g., Option I-D, Option 16 II, Enhanced Option I-A, and the ABSP for DSS-CD), this change would result in earlier (i.e.,
17 conservative) RPS actuation. The NRC staff reviewed this response and determined that it is 18 not clear that a high APRM signal is always conservative for the ABSP. However, this backup 19 solution is only used when the normal stability protection is inoperable and its use is limited to 20 120 days. Therefore, the proposed change would negligibly affect the ABSP and is acceptable 21 to the NRC staff.]
22 23 The regulation at 10 CFR 50.36(c)(3) requires that the TSs contain SRs, which are 24 requirements relating to test, calibration, or inspection to assure that the necessary quality of 25 systems and components is maintained, that facility operation will be within safety limits, and 26 that the limiting conditions for operation will be met. The NRC staff reviewed the changes 27 proposed to SR 3.3.1.1.2 as described in this SE. The NRC staff determined that the SR, as 28 modified, continues to provide appropriate controls and acceptance criteria for adjustment of the 29 APRMs to ensure that the APRMs appropriately reflect actual reactor power. The NRC staff 30 determined that the SR continues to verify the operability of the APRMs and provide assurance 31 that the necessary quality of systems and components is maintained.
32 33 3.1 VARIATIONS FROM THE APPROVED TRAVELER 34 35
[NOTE: Technical reviewers and/or project manager to discuss variations from the approved 36 traveler and whether they are acceptable.]
37 38
3.2 CONCLUSION
39 40 The NRC staff reviewed the proposed changes to the TSs, and determined that they meet the 41 standards for TSs in 10 CFR 50.36(b). The proposed changes to the SR assure that the 42 necessary quality of systems and components is maintained, that facility operation will be within 43 safety limits, and that the LCOs will be met, and satisfy 10 CFR 50.36(c)(3). Additionally, the 44 changes to the TSs were reviewed for technical clarity and consistency with customary 45 terminology and format in accordance with SRP Chapter 16.
46 47
4.0 STATE CONSULTATION
1 2
[Note: This section is to be prepared by the PM.]
3 4
In accordance with the Commission's regulations, the [Name of State] State official was notified 5
of the proposed issuance of the amendment on [enter date]. The State official had [no]
6 comments. [If comments were provided, they should be addressed here].
7 8
5.0 ENVIRONMENTAL CONSIDERATION
9 10
[Note: This section is to be prepared by the PM. As needed, the PM should coordinate with 11 NRRs Environmental Review and Projects Branch (RERP) to determine the need for an EA.
12 Specific guidance on preparing EAs and considering environmental issues is contained in NRR 13 Office Instruction LIC-203, Procedural Guidance for Preparing Categorical Exclusions, 14 Environmental Assessments, and Considering Environmental Issues.]
15 16 The amendment changes a requirement with respect to the installation or use of facility 17 components located within the restricted area as defined in 10 CFR Part 20 or changes to SRs.
18 The NRC staff has determined that the amendment involves no significant increase in the 19 amounts, and no significant change in the types, of any effluents that may be released offsite, 20 and that there is no significant increase in individual or cumulative occupational radiation 21 exposure. The Commission has previously issued a proposed finding that the amendment 22 involves no significant hazards consideration, and there has been no public comment on such 23 finding [(XX FR XXX)]. Accordingly, the amendment meets the eligibility criteria for categorical 24 exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental 25 impact statement or environmental assessment need be prepared in connection with the 26 issuance of the amendment.
27 28
6.0 CONCLUSION
29 30 The Commission has concluded, based on the considerations discussed above, that (1) there is 31 reasonable assurance that the health and safety of the public will not be endangered by 32 operation in the proposed manner, (2) there is reasonable assurance that such activities will be 33 conducted in compliance with the Commission's regulations, and (3) the issuance of the 34 amendment will not be inimical to the common defense and security or to the health and safety 35 of the public.
36 37
7.0 REFERENCES
38 39 Optional section to be prepared by the PM and technical reviewers. If document is publicly 40 available, the ADAMS Accession No. should be listed.
41 42
[NOTE: Replace principal contributor names with the individual(s) who prepare the plant-specific 43 SE.]
44 Principal Contributors:
Jennifer M. Whitman, NRR/DSS/SRXB 45 Gursharan Singh, NRR/DE/EICB 46 47 Date: June 20, 2017 48 49