BECO-87-087, Application for Amend to License DPR-35,consisting of Proposed Change 87-07,changing Table 4.2.G, Min Test & Calibr Frequency for ATWS Rpt/Ari Instrumentation & 4.2.G Bases

Application for Amend to License DPR-35,consisting of Proposed Change 87-07,changing Table 4.2.G, Min Test & Calibr Frequency for ATWS Rpt/Ari Instrumentation & 4.2.G Bases

ML20214N688
Person / Time
Site:	Pilgrim
Issue date:	05/20/1987
From:	Bird R BOSTON EDISON CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20214N693	List: BECO-87-087, Application for Amend to License DPR-35,consisting of Proposed Change 87-07,changing Table 4.2.G, Min Test & Calibr Frequency for ATWS Rpt/Ari Instrumentation & 4.2.G Bases ML20214N703
References
BECO-87-087, BECO-87-87, NUDOCS 8706030020
Download: ML20214N688 (6)

Text

10CFR50.90 O

.0amason Executiw Offices 800 Boyhton Street Boston, Massachusetts 02199 May 20, 1987 BECo 87- 087 Proposed Change 87-07 Ralph G. Bird Senior Vice President - Nuclear U. S. Nuclear Regulatory Commission Document Control Desk Hashington, DC 20555 License DPR-35 Docket 50-293 Proposed Technical Soecification Chanar_to Table 4.2.G " Maximum Test and Calibration Freauency for ATHS RPT/ARI Instrumentation" and 4.2.G Bases

Dear Sir:

Pursuant to 10CFR50.90, Boston Edison Company (BECo) proposes the following revisions to Facility Operating License No. DPR-35, Appendix A, Table 4.2.G, and its Bases. The requested changes are described in Attachment A, and the revised Technical Specification pages are contained in Attachment B.

An application fee of one hundred and fifty dollars ($150.00) will be electronically mailed to your offices in accordance with the requirements of 10CFR Part 170.12 (c).

. G. ird PHK/cs Attachments: (A) Description of Proposed Change (B) Amended Technical Specification Pages 1 signed original and 37 copies cc: See next page Commonwealth of Massachusetts)

County of Suffolk )

Then personally appeared before me, Ralph G. Bird, who, being duly sworn, did state that he is Senior Vice President - Nuclear of Boston Edison Company and that he is duly authorized to execute and file the submittal contained herein in the name and on behalf of Boston Edison Company and that the statements in said submittal are true to the best of his knowled and belief.

My commission expires: dchdeo J/ /186 - '

M b DATE' NOTARY /PUBLIC

~

'B706030020 870520 0 PDR ADOCK 05000293 0' P PDR .

BOSTON EDISON COMPANY U. S. Nuclear Regulatory Commission Page 2 cc: Mr. R. H. Nessman, Project Manager Division of Reactor Projects I/II Office of Nuclear Reactor Regulations U. S. Nuclear Regulatory Commission 7920 Norfolk Avenue-Bethesda, MD 20814 U. S. Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA 19406 Senior NRC Resident Inspector Pilgrim Nuclear Power Station Mr. Robert M. Hallisey, Director Radiation Control Program Mass. Dept. of Public Health 150 Tremont Street F-7 Boston, MA 02111 l

Proposed Chance A change is proposed to Pilgrim Nuclear Power Station Operating License No.

DPR-35,-pages 66b and 77.

The proposed change adds a reference to Note (7) to the column headed

" Instrument Functional Test." Note (7) states:

Calibration of analog trip units will be performed concurrent with functional testing. The functional test will consist of injecting a simulated electrical signal into the measurement channel. Calibration of associated analog transmitters will be performed each refueling outage.

The proposed change also substitutes Note (7) for the current wording found in the " Calibration" column. The Bases wording is modified to make it more current and reflect the proposed changes.

Reason For Chanae It has-been identified that the surveillance frequency of the ATHS RPT/ARI system currently specified in the Technical Specifica61ons is overly conservative. Presently the Technical Specifications require a one to three month surveillance test interval.

Currently. Table 4.2.G, which provides test and calibration frequencies for ATHS RPT/ARI instrumentation, references note (1) in the column headed

" Instrument Functional Test." Note (1) states:

Initially once per month until exposure hours (M as defined on Figure 4.1.1) is 2.0x10b; thereafter, according to Figure 4.1.1 with an interval not less than one month nor more than three months.

A review of procedures and industry practices for testing analog devices revealed that the transmitter undergoes an " instrument functional test" when calibrated at a frequency of once/ cycle. The technical specification as currently worded is overly conservative because of the inherent reliability of I

analog devices, because of the continuous self-checking characteristics of i such devices, and, most important, because strict compliance would subject the plant to a higher risk of spurious scrams when the transmitter is isolated to allow a " simulated signal" to be introduced into it during normal operations.

The introduction of Note (7) onto Table 4.2.G corrects the problem and makes l the table. consistent with other Pilgrim technical specifications that involve i analog transmitters.

l l NEDO 21617-A, Analoo Transmitter / Trio Unit System for Enain?ered Safeauard Transmitter Trio Inout, a Topical Report for which notice of NRC acceptance was issued on June 27, 1978, has already established a once/ cycle functional I test frequency for analog transmitters. It is reflected in Technical i Specification Note (7), which applies to Pilgrim's analog transmitters.

l Revising Table 4.2.G to reference Note (7) will reflect that the transmitters l are analog, and preclude the risk of spurious scrams generated by the needless isolation required to allow the injection of a simulated signal into the transmitters.

1 l

l i.--

This propssed change will bring the Technical Specifications. into conformance with industry recommendations and practices for analog transmitters.

Safety Evaluations and Determination of No Sianificant Hazards Considerations The ATHS RPT/ARI System is designed to provide a back-up method for adding negative reactivity to the reactor in the unlikely event of a failure of the reactor to scram (ATHS - Anticipated Transient Hithout Scram). The system is

' initiated through coincident receipt of low-low water level and/or high reactor pressure signals.

Electronic transmitters provide level and pressure signals to Analog Trip Units (ATU) that energize auxiliary relays. The trip channels are arranged in a two-out-of-two once logic, The trip of either channel will result in tripping both Recirculation Pump MG set field breakers, the subsequent trip of both Recirculation Pumps (RPT, Recirculation Pump Trip), and energization of an alternate solenoid scram valve causing insertion of all control rods (ARI, Alternate Rod Insertion).

The change affects the testing requirements of the ATHS RPT/ARI System described in Section 3.9 of the FSAR and found on Table 4.2.G. Testing of the transmitters will be performed once a cycle at calibration rather than at its current once per month frequency.

The proposed change will not affect the safety function of the system. The potential result of the change would solely be an impact on the reliability of the system as a result of the transmitter test frequency. ,

The Code of Federal Reaulations,-10CFR50.91 requires that at the time a licensee requests an amendment, it must provide to the Commission its analysis, using the standards in 10CFR50.92, about the issue of no significant hazards consideration. Therefore, in accordance with 10CFR50.91 and 10CFR50.92, the following analysis has been performed.

1. Operating Pilgrim Station in accordance with the proposed amendment will not involve a significant increase in the probability or consequences of an accident previously evaluated.

The proposed amendment will not involve a significant increase in the probability or consequences of an accident previously evaluated because

the availability, accuracy and reliability of the analog transmitters identified on Table 4.2.G is not reduced by this change. In fact, overall availability is enhanced because the injection of a simulated signal into the transmitter requires that it be isolated during power operation, reducing its availability to perform its designed function. Isolation

, also creates a higher risk of a spurious scram. Compliance with the existing requirement does not enhance safety because, as detailed in NED0 21617-A, the type of transmitter being surveilled is subject to constant cross-checking by comparison of its output currents against other transmitters in the system. This provides a means to determine if a transmitter is malfunctioning without periodically isolating it and injecting a simulated signal into it. A gross failure immediately activates an annunciator in the control room. Minor " drifting" is detected by the daily instrument checks required by Technical Specification Table 4.2.G.

i

- , - ~ . , _ - . , - . - - . _ . . .

, ,,v.,,,., . _ . - . , , , , . , _ , _ . , ,. . . . . . _ . , _..,,,..-,,,_y... , , . - . . , . , _ , _ . . . . . _ _ , . _ . _ . , , . . - _ _ , _ . -

These constant checks, along with the proven reliability of the transnitters, is reflected by the once/ cycle calibraticn of transaitters found in the calibration column of Table 4.2.G. Therefore this change will not involve a significant increase in probability or consequences of a previously evaluated accident.

2. Operating Pilgrim Station in accordance with the proposed amendment will not create the possibility of a new or different kind of accident from any i accident previously evaluated.

The proposed amendment does not create a new or different kind of accident from any previously evaluated because the ATHS RPT/ARI was designed and installed as a backup to other Reactor Protection Systems (RPS) signals.

The instrumentation is intended to function in transients not covered by the primary Control Rod (CR) insertion signals; therefore the instruments enhance safety. The change does not create new or different accident scenarios; In fact, the change is beneficial because isolating the analog transmitters to perform the currently required surveillance reduces the availability of the ATHS RPT/ARI to perform its designated function, and increases the potential for a spurious scram.

The reliability of these instruments, coupled with the required daily l check and constant alarmed monitoring ensure that the accuracy, availability and reliability of the transmitters will be unchanged by the proposed amendment. Therefore this proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.

3. Operating Pilgrim Station in accordance with the proposed amendment will not involve a significant reduction in a margin of safety.

The proposed amendment does not involve a significant reduction in a margin of safety. The only potential impact on the margin of safety involved in this proposal is associated with the reliability, accuracy and availability of the transmitter. As discussed in (1) and (2) above, the change will improve instrument reliability, accuracy and availability:

(a) Honthly testing of the transmitters will not increase reliability.

Industry experience and recommendations indicate the reliability of the transmitters can be assured by testing once/ refueling. This is reflected in the once/ operating cycle calibration for the transmitters already found on Table 4.2.G.

(b) Monthly testing will not improve our ability to detect instrument malfunctions because the accuracy of the instrument is detectable on a daily basis. Gross failure or deviation is immediately identified through a control room alarm. Since a loss of accuracy has a direct impact on the confidence level assigned to relying on an instrument to guarantee a previously chosen safety margin, and since transmitter accuracy is in this case indicated on a constant basis, a high level of confidence in the transmitter's accuracy can be assumed because deviation will be quickly detected and corrected; therefore the component of the safety margin reliant on transmitter accuracy also has a high confidence level.

(c) The proposed amendment actually improves transmitter availability because the transmitter would not need to be isolated during normal operations to allow a simulated signal to be injected into it.

~

Additionally, keeping all trans2itters available during normal operaticn reduces the chance of a spurious scram caused by isolating for surveillance. This aids in maintaining the safety margin.

For these reasons, operating Pilgrim in accordance with the proposed amendment does not involve a significant reduction in a margin of safety.

This change does not involve an unresolved safety question as defined in 10CFR 50.59. It has been reviewed and approved by the PNPS Operations Review Committee and reviewed by the Nuclear Safety Review and Audit Committee.

Schedule of Chanae This change will become effective within 30 days of BECo's receipt of approval by the NRC.