ML20209F791

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Safety Evaluation Re Util 830802 SAR & 840904 Addl Info Re Spds,Provided as Part of Emergency Response Facility Data Sys.Submittals Acceptable Per NUREG-0737
ML20209F791
Person / Time
Site: 05000000, Diablo Canyon
Issue date: 03/19/1985
From:
NRC
To:
Shared Package
ML082410749 List: ... further results
References
FOIA-86-197, RTR-NUREG-0737, RTR-NUREG-737 NUDOCS 8704300376
Download: ML20209F791 (3)
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.u SAFETY EVALUATION - DIABLO CANYON, UNITS 1 AND 2 SAFETY PARAMETER DISPLAY SYSTEM (SPDS)

I.

BACKGROUND In order to satisfy the NRC requirements concerning the Safety Parameter Display System (SPDS), Pacific Gas and Electric (PG&E) Company, the licensee for Diablo Canyon Nuclear Station submitted a Safety Analysis Report (SAR) on August 2, 1983. This report provided a description of the SPDS as part of the Emergency Response Facility Data System (ERFDS). The SAR did not include enough information addressing the requirements that the SPDS must be suitably isolated from equipment and sensors that are used in safety systems to prevent electric and electronic interference. On June 27, 1984, a request was sent to the licensee to obtain additional information on the isolation devices used between safety systems and the SPDS. PG&E provided the necessary information on' September 4, 1984. Our evaluation addresses the qualification and doc-umentation of the isolators as an acceptable interface between the Class 1E safety-related instrumentation systems and the SPDS.

II. EVALUATION The SPDS at Diablo Canyon Units 1 and 2 has been implemented as part of the ERFDS. The SPDS for each unit is described as a computer based system con-sisting of a data acquisition system, two master receivers, two data handler computers and two SPDS computers, each feeding a separate SPDS channel. Each SPDS channel is implemented with a color video monitor on the main control panel. Each channel also includes a redundant video generator which provides a color video monitor in the Technical Support Center (TSC). The two separate 8704300376 070417 PDR FOIA HOLMES86-197 PDR

. channels of hardware used in this design achieve a high reliability for the SPDS.

4 The data acquisition system is comprised of a. high speed, remote multiplex 1 rig system that interfaces with plant instrumentation. Eleven remote multiplexers collect and digitize data from plant sensors. This data is then transmitted to a master receiver through a sub-multiplexer and signal conditioning unit via a fiber o'p' tic data link. PG8E states that the remote multiplexers that interface with Class 1E system instrumentation are qualified Class 1E devices.

Isolation between the multiplexers and the remaining SPDS equipment is achieved by way of the fiber optic data links.

This fiber optic cable which transmits digital information using light instead of electric current is a unique isolator which possesses inherent character-istics that eliminate ground loops and common ground shifts in electronic cir--

cuits and provides complete electrical ground isolation between transmitter and receiver.

Fiber optic cables present no fire hazards when their fibers are damaged.

In addition no local secondary damages can occur because fiber optics neither produce sparks nor dissipate heat. The construction of the fiber optic cable is such that the cable contains no electrically conductive material. The relative permittivity (dielectric constant) of a material is a measure of the material's isolation capability. The dielectric constant of a material is referenced relative to free space (a vacuum) and is a dimension-less number. Dry air possesses a dielectric constant of 1.00059. Glass possesses a dielectric constant in the range of 4.0 to 7.0 depending upon the i

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. specific type. The higher the dielectric constant, the greater the isolation that is provided. Thus, fiber-optic cables have an isolation capability that is 4 to 7 times greater than dry air. The voltage breakdown rating of a typical fiber-optic cable is on the order of 250 KV per meter.

A fault at either end of the data link might destroy the modem but will not propagate over the fiber-optic cable.

For example, one of the tests that must be performed to ' qualify an isolator is the application of the maximum credible fault (voltage, current) to the output of the device to verify that the fault does not propagate or degrade the input (Class 1E) side. This postulated failure does not affect fiber-optic cable, as stated above, the optical fibers are totally dielectric (i.e., the electrical energy resulting from the fault will not propagate through the optical fiber). Another char-acteristic of the optical fiber cable is its nonsusceptibility to the coupling of cross-talk and electromagnetic interference (EMI).

III. CONCLUSION Based on our audit of the PG&E information on the isolation devices used in

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the Diablo Canyon design, we conclude that the design methodology and the hardware used for interfacing the ERFDS/SPDS with safety-related systems are acceptable, and that this equipment meets the Comission's requirements of NUREG-0737, Supplement No. 1.

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MAR 181985 MEMORANDUM FOR: Chairman Palladino Commissioner Roberts

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Comissioner Asselstine Commissioner Bernthal l

Commissioner Zech FROM:

William J. Dircks i

i Executive Director for Operations 1

Sil8 JECT:

DIABLO CANYON UNIT 2 LICENSING SCHEDULE - NEED

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FOR EFFECTIVENESS REVIEW i

Pacific Gas and Electric Company (PG&E) informed the staff, in a letter dated January 31, 1985, that Diablo Canyon Unit 2 should be ready to load i

fuel by the erd of March 1985. The staff's review of licensing issues and i

allegations is continuing. On March 14, we issued Supplement No. 29 to the Diablo Canyon Safety Evaluation Report which addresses design verification as it relates to Unit 2.

In the near future, we expect to issue Supplemental Safety Evaluation Reports (SSERs) which will address (1) the resolution of all of the allegations received before July 31, 1984, and the resolution or status of all allegations received before January 31,19$5, with respect to Units 1 and 2 and (2) all of the other pertinent licensing issues. Allegations 3

received after January 31, 1985 will be screened by the staff prior to issuance of any operating license-and-will be addressed in a subsequent 'SSER.

a In September 1981, the Commission amended 10 CFR 2.764 to eliminate the need for Comission review of licensing board decisions to the extent of allowing plant fuel load and operation up to five percent of rated power (46 FR 47764, 1

September 30,1981). However, in taking this action, the Comission specifically noted, in the accompanying Statement of Considerations,. that such procedures would not apply to cases like Diablo Canyon where the licensing decision was issued before the effective date of the amendment (September 23,1981). Boaru decisions issued before that date which authorize the issuance of a low power operating license are to be reviewed by the Comission before becoming effective, in accordance with the Comission's amendment to 10 CFR 2.764 effective on May 28, 1981, (46 FR 28627). This is in addition to the effectiveness' review required prior to the issuance of a full power license.

In referring to Diablo Canyon, the Comission did not distinguish between Units 1 and 2; an affectiveness l

review by the Comission appears, therefore, to be required prior to issuance of an operating license authorizing fuel load and low power testing up to 5%

of rated power for Unit 2.

CONTACT:

C. Grimes, NRR X28414 MO"-

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l The Comissioners. 9 The Commission performed an effectiveness review in September 1981, in connection with the issuance of a low power license for Unit 1 (CLI-81-22, 14 NRC 598). The Commission's full powet effectiveness review for Unit I was completed in August 1984 (CLI-84-13, 20 NRC 267). The staff does not believe that there is any significant difference in the units relative to the effect-iveness review factors set forth in 10 CFR 92.764. This should facilitate the Comission's effectiveness review.

Similarly, the staff believes that the Unit 2 allegation-related matters and other pertinent licensing issues on which it is completing its review are, in general, of the same nature as those previously reviewed in connection with Unit 1, on which the Comission was briefed. Therefore, the staff does not believe that any further briefing on these matters is necessary and, upon completion of the Commission's effectiveness review, we are prepared to issue a low-power license for Diablo Canyon Unit 2 as soon we have has established that all other matters are satisfactorily resolved.

(Signed William J.Dircks William J. Dircks Executive -Director for Operations cc: SECY OGC-OPE DISTRIBUTION:

NRC PDR L PDR OELD Docket No. 50-323 PPAS WDircks HDenton/DEisenhut HThompsor/FMiraglia CGrimes SEP Rdg.

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CKirsch, RV

  • PREVIOUS C0hCURRENCES OBTAINED SEP8:DL LB#3:DL LB#3:DL AD:L:DL OELD DD:DL
  • CGrimes:dk
  • HSchierling
  • GKnighton
  • TNovak
  • LChandler *FMiraglia 2/19/85 2/19/85 2/19/85 2/22/85 2/26/85 3/6/85 D:DL DD:NRR D:NRR ED0 s
  • HThompson
  • DEisenhut
  • HDenton WDircks 3/6/85 3/13/85 3/13/85 3/ /85

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