ML15050A195
| ML15050A195 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 02/18/2015 |
| From: | Tam P Plant Licensing Branch IV |
| To: | Baldwin T, Schrader K Pacific Gas & Electric Co |
| References | |
| TAC MF3240, TAC MF3241 | |
| Download: ML15050A195 (5) | |
Text
1 NRR-PMDAPEm Resource From:
Tam, Peter Sent:
Wednesday, February 18, 2015 5:18 PM To:
'Schrader, Kenneth'; 'Baldwin, Thomas (DCPP)'
Cc:
Carte, Norbert; Lingam, Siva
Subject:
Diablo Canyon - RAI on instrumentation and controls for the proposed TSTF-505 amendment (TAC MF3240 and MF3241)
Ken, Tom:
Please find below a Request for Additional Information (RAI) in the instrumentation and controls area of the subject proposed amendment. The RAI was previously sent to you in draft form on January 30, 2015, by our Diablo Canyon project manager, Siva Lingam. You (Ken) indicated that your staff understand the questions and that there is no need to discuss the questions in a conference call.
We have made no substantive changes to the questions from their draft form, except perhaps some minor editorial changes.
I discussed with you (Ken) a proposed target date for your formal response to this RAI. We agreed that May 4, 2015, is the target date (about 75 days from the date of this email).
This email will be immediately entered into NRCs Official Agency Record system ADAMS, and will be made publicly available 10 days later. If you believe any parts of this email contain sensitive information that should not be disclosed to the public, please let me know within the next 10 days.
Peter S. Tam Senior Project Manager (rehired annuitant)
Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST TO REVISE TECHNICAL SPECIFICATIONS TO IMPLEMENT TSTF-505, REVISION 1, PROVIDE RISK-INFORMED EXTENDED COMPLETION TIMES - RITSTF INITIATIVE 4B DIABLO CANYON POWER PLANT, UNITS 1 AND 2 TAC NOS. MF3240 AND MF3241 By letter dated November 25, 2013 (Agencywide Documents Access and Management System (ADAMS)
Accession No. ML13330A557), Pacific Gas and Electric Company (PG&E, the licensee) submitted a License Amendment Request (LAR) regarding Diablo Canyon Units 1 and 2 Facility Operating License. The proposed amendment would Revise Technical Specifications to Implement TSTF-505, Revision 1, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b. The technical review branch for instrumentation and control (I&C) has identified the need for additional information to complete the review of the LAR:
1 The LAR proposes adding Technical Specification (TS) Section 5.5.20, Risk Informed Completion Time Program, to the technical Specifications, which states:
This program provides controls to calculate a Risk Informed Completion Time (RICT) and must be implemented in accordance with NEI 06-09, Revision 0, "Risk-Managed Technical Specifications (RMTS) Guidelines." The program shall include the following
2 The safety evaluation (SE) associated with the U.S. Nuclear Regulatory Commission approval of NEI 06-09, Revision 0 (ADAMS Accession No. ML063390639) qualified the approval of NEI 06-09, Revision 0 and is included in NEI 06-09 (Revision 0) -A (ADAMS Accession No. ML12286A322). For example, the NRC qualifications includes:
RG 1.200, Revision 1, was issued in January 2007, which endorsed the updated standard applicable for internal events PRA models. The NRC staff takes exception to the reference to RG 1.200, Revision 0, currently listed throughout TR NEI 06-09, Revision 0. The NRC staff will require an assessment of PRA technical adequacy using the revised RG 1.200, Revision 1, and the updated PRA standard.
It is understood that the -A version was not referenced because TSTF-505 did not reference it.
Please explain how the qualifications in the SE are incorporated.
2 The SE associated with NEI 06-09, Revision 0 states:
PRA Modeling. TR NEI 06-09, Revision 0, specifically applies the RMTS only to those SSCs
[Systems Structures or Components] which mitigate core damage or large early releases. Where the SSC is not modeled in the PRA, and its impact cannot otherwise be quantified using conservative or bounding approaches, the RMTS are not applicable, and the existing frontstop CT would apply.
It is understood that part of the Reactor Trip System (RTS) and Engineer Safety Features Actuation System (ESFAS) functions described in TS Tables 3.3.1-1 and 3.3.2-1 are implemented in four cabinets of Eagle 21 equipment.
- a. Please describe the Probabilistic Risk Assessment (PRA) model for the Reactor Trip System (RTS),
and any conservative or bounding approaches for parts of the RTS that are not modeled. Please be sure to include a description of how equipment shared between RTS functions is modeled in the PRA.
- b. Please describe the PRA model for the Engineered Safety Features Actuation System (ESFAS) and any conservative or bounding approaches for parts of the ESFAS that are not modeled. Please be sure to include a description of how equipment shared between ESFAS functions is modeled in the PRA.
3 The single failure criterion requires that a system which is designed to perform a defined safety function must be capable of meeting its objectives assuming the failure of any major component within the system or in an associated system which supports its operation.
The limiting condition for operation (LCO) in the TS allows a limited period of operation in a condition where the single failure criterion is not met. That is, given that a single failure has occurred, a plant is allowed a limited time of operation in this configuration (i.e., a configuration that could not tolerate a second failure). During this limited time, the plant must either establish a plant configuration that can tolerate another failure, or transition to an operating mode where the safety function is not required.
A plant is never allowed to operate in a configuration where a protection system or a safety system is unable to perform its required safety functions.
For the specific case where a protection system and a control system share components, there are additional regulatory requirements that must be considered. These additional requirements are sometimes referred to as the separation of protection and control criterion, and include:
3 GDC 24 Separation of protection and control systems. The protection system shall be separated from control systems to the extent that failure of any single control system component or channel, or failure or removal from service of any single protection system component or channel which is common to the control and protection systems leaves intact a system satisfying all reliability, redundancy, and independence requirements of the protection system...
IEEE 279-1971 4.7 Control and Protection System Interaction.
4.7.3 Single Random Failure. Where a single random failure can cause a control system action that results in a generating station condition requiring protective action and can also prevent proper action of a protection system channel designed to protect against the condition, the remaining redundant protection channels shall be capable of providing the protective action even when degraded by a second random failure.
Provisions shall be included so that this requirement can still be met if a channel is bypassed or removed from service for test or maintenance purposes. Acceptable provisions include reducing the required coincidence, defeating the control signals taken from the redundant channels, or initiating a protective action from the bypassed channel.
For the RTS and ESFAS, please identify all of the instances where equipment or information is shared between protection and control systems.
4 Protection systems and safety systems have two or more redundant elements, and these elements are arranged in typical voting arrangements, for example:
1 out of 2 (e.g., Manual Reactor Trip) 2 out of 3 (e.g., Pressurizer Water Level-High) 2 out of 3 (per loop) (e.g., Reactor Coolant Flow-Low) 2 out of 4 (P&C) (e.g., See response to Question No. 3 above) 2 out of 4 (no P&C)
For each RTS & ESFAS voting arrangement, please state the minimum number of redundancies that must be functional (i.e., TS Operable and/or PRA Functional), so the RTS and ESFAS system can still perform their required safety functions.
5 LAR Enclosure Attachment No. 5. Table A5-2 contains RICT estimates for some conditions, for example:
The first row addresses Condition B, one of two manual reactor trip channels inoperable, and identifies the calculated RICT. It is assumed the RICT is calculated based on the inoperable channel being PRA Functional, because a RICT is not applicable for a loss of function.
- a. Is the single failure criterion met in each of these conditions? Please explain.
- b. Please state if the separation of protection and control criterion is applicable, and if so, how it is met in each of these conditions.
6 The second row of Table A5-2 identifies the calculated RICT for, (Various Conditions) one of two credited automatic RTS functions inoperable. It is assumed the RICT is calculated based on the inoperable channels being PRA Functional, because a RICT is not applicable for a loss of function.
4 Please describe each condition and the two credited automatic RTS functions for each.
7 Table A5-2 generally does not tabulate the RICT for the RTS and ESFAS functions when Two or morechannels inoperable.
- a. Please provide tabulated RICTs for each configuration (i.e., 2, 3, or 4 channels inoperable) associated with Two or morechannels inoperable. Please include the case where one or more channels are not PRA functional.
- b. Is the single failure criterion met in each of these configurations? Please explain.
- c. Please state if the separation of protection and control criterion is applicable, and if so, how it is met in each of these configurations.
8 Section 3.2.2 of NEI 06-09 Revision 0-A states:
This guidance is intended to address separate operability and PRA functionality assessments which would allow a component to be considered both inoperable and PRA Functional based on the evaluation of the same degraded condition.
Please provide some example conditions that would allow RTS and ESFAS components to be considered both inoperable and PRA Functional.
Hearing Identifier:
NRR_PMDA Email Number:
1880 Mail Envelope Properties (0A64B42AAA8FD4418CE1EB5240A6FED10195BA4A7E8E)
Subject:
Diablo Canyon - RAI on instrumentation and controls for the proposed TSTF-505 amendment (TAC MF3240 and MF3241)
Sent Date:
2/18/2015 5:17:42 PM Received Date:
2/18/2015 5:17:00 PM From:
Tam, Peter Created By:
Peter.Tam@nrc.gov Recipients:
"Carte, Norbert" <Norbert.Carte@nrc.gov>
Tracking Status: None "Lingam, Siva" <Siva.Lingam@nrc.gov>
Tracking Status: None
"'Schrader, Kenneth'" <KJSe@pge.com>
Tracking Status: None
"'Baldwin, Thomas (DCPP)'" <TRB1@pge.com>
Tracking Status: None Post Office:
HQCLSTR02.nrc.gov Files Size Date & Time MESSAGE 10611 2/18/2015 5:17:00 PM Options Priority:
Standard Return Notification:
No Reply Requested:
No Sensitivity:
Normal Expiration Date:
Recipients Received: