ML19309C616

Electrical,Instrumentation & Control Aspects of Proposed Tech Specs Change Re Blocking of Safety Injection Signals When Pressure Is Below 2000 Psig, Technical Evaluation Rept

ML19309C616
Person / Time
Site:	Robinson
Issue date:	02/29/1980
From:	Mays S EG&G, INC.
To:	Shemanski P Office of Nuclear Reactor Regulation
References
CON-FIN-A-6256 EGG-EA-5106, NUDOCS 8004090068
Download: ML19309C616 (8)

Text

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INTERIM REPORT Accession No.

Report No. EGG-EA-5106 C:ntract Program or Project

Title:

Electrical, Instrumentation and Control Systems Support Subject of this Document: Electrical, Instrumentation & Control Aspects of Proposed Technical Specifications Change Regarding Blocking of Safety Injection Signals when Pressure is Below 2000 psig.

H. B. Robinson, Unit 2 Type of Document:

Technical Evaluation Report S. E. Mays Author (s):

otte of Document: February 1980 R:sponsible NRC Individual and NRC Office or Division: Paul Shemanski. Division of Operating Reactors This document was prepared primarily for preliminary or internal use. It has not received full review and approval. Since there may be substantive changes, this document should not be considered final.

EG&G Idaho. Inc.

idaho Falls. Idaho 83401 k +j .C

, H.iP.' Pearson, Supervisor

[" Information Processing Prepared for the U.S. Nuclear Regulatory Commission and the U.S. Department of Energy Idaho Operations Office Under contract No. EY-76-C-07-1570 NRC FIN No.

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EGG-EA-5106 February 1980 ELECTRICAL. INSTRUMENTATION AND CONTR0!. ASPECTS OF l

5 PROPOSED TECilNICAL SPECIFICATIONS tilANCE RECARDING l ilLOCKING OF SAFETY INJECTION SIGNALS WilEN PRESSURE  !

l IS BELOW 2000 PSIC.11. B. ROBINSON, UNIT 2 '

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U.S. Department of Energy  !

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Fopu tcao m (Rev 11 F9)

INTERIM REPORT Accession No.

, Report No. EGG-EA-5106 C ntract Program or Project

Title:

Electrical, Instrumentation and Control Systems Support Subject of this Document:

Electrical, Instrumentation and Control Aspects of Proposed Technical Specifications Change Regarding Blocking of Safety Injection Signals when Pressure is Below 2000 psig,

11. B. Robinson, Unit 2 Type of Document:

Technical Evaluation Report Author (s):

S. E. Kays D t) of Document:

February 1980 R:sponsible NRC Individual and NRC Office or Division:

Paul Shemanski, Division of Operating Reactors This document was prepared primarily for preliminary or internal use. lt has not received full review and approval. Since there may be substantive changes, this document should not be considered final.

EG&G Idaho, Inc.

Idaho Falls, Idaho 83415 Prepared for the U.S. Nuclear Regulatory Commission Washington, D.C.

Under DOE Contract No. DE-AC07 76lD01570 NRC FIN No. A6256 INTERIM REPORT fkO h C i,t piri gt h jiggi ftd y r g .-l

1030F TECHNICAL EVALUATION REPORT ELECTRICAL, INSTRUME!(IATION, AND CONTROL ASPECTS OF -

PROPOSED TECHNICAL SPECIFICATIONS CHANGE REGARDING BLOCKING OF SAFETY INJECTION SIGNALS MIEN PRESSURE IS BELOW 2000 PSIC H. B. ROBINSON, UNIT 2 Docket No. 50-261 February 19809 S. E. Mays f

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CONTENTS 1.0 IITTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.0 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3.0 EVALUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

4.0 REFERENCES

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9 9 11 1

TECHNICAL EVALUATION REPORT ELECTRICAL, INSTRUMENTATION, AND CONTROL ASPECTS OF PROPOSED TECHNICAL SPECIFICATIONS CHANGE REGARDING BLOCKING OF SAFETY INJECTION SIGNALS WHEN PRESSURE IS BELOW 2000 PSIG H. B. ROBINSON, UNIT 2

1.0 INTRODUCTION

The objective of this review is to evaluate if plant safety is degraded by allowing the proposed changes to the H. B. Robinson, Unit 2 Technical Specifications to allow blocking the "High Differential Pres-sure Between any Steam Line and the Steam Header" Safety Injection System (SIS) initiation when primary plant pressure is less than 2000 psig (as in cooldown operations). This change was proposed by Carolina Power and Light Company in their letter Utley to Schwencer dated March 6, 1979.

2.0 DISCUSSION The present H. B. Robinson, Unit 2 Technical Specifications allow blocking the " Pressurizer Low Pressure and Low Level" SIS initiation when primary pressure is less than 2000 psig (as in cooldown oper-ations). However, the same switch which blocks this signal also blocks the "High Differential Pressure Between any Steam Line and the Steam Header" SIS initiation. Table 3.5.3 of the Technical Specifications presently does not allow this signal to be blocked under any condi-tions. Therefore, Carolina Power and Light Company has requested that Tabic 3.5.3 of the Technical Specifications be changed to allow block-ing the "High Differential Pressure Between any Steam Line and the Steam Header" when primary plant pressure is less than 2000 psig.

Section 14.2.5 of the H. B. Robinson, Unit 2 Final Facility Description and Safety Analysis Report (FEAR) discusses the factors protec ting the core in the event of a steam line rupture. The SIS initiation and rapid closure of the main steam isolation valves is required to ensure that the possible return to criticality will not I

F-result in sufficient heat flux to cause core damage and to ensure that adequate shutdown margin is maintained.

SIS initiation and rapid closure of the main steam isolation valves during a steam line rupture can be initiated by any of the following s ignals . .

(1) Pressurizer Low Level and Low Pressure (2) High Differential Pressure Between any Steam Line and the Steam Header (3) - High Containment Pressure (4) High Steam Flow in 2/3 Steam Lines Coincident with Low T avg or Low Steam Pressure. .

Technical Specifications, Table 3.5.3 allows blocking signal (1) above .

when primary pressure is less than 2000 psig. The proposed change would also allow signal (2) above to be blocked when pressure is less than 2000 psig.- This would leave only signals (3) and (4) above avail-able for SIS initiation and rapid closure of the main steam isolation valves in the event of a steam line rupture. Table 3.5.3 of the ~ Tech-nical Specifications requires a minimum of two containment pressure channels to be operable with one degree of redundancy. It also requires operability of at least one steam line flow channel per loop, two T ,y channels with one degree of redundancy, and two steam pressure channels with ~ one degree of redundancy. Therefore, SIS initiation and core protection is provided by two separate redundant systems if both sig-nals (1) and (2) above are blocked when the primary pressure is below 4

2000 psig.

Furthermore, as noted in NRC Memo f rom J. H. - Sniezek to 'D. Eisenhut, dated April 5,1978, the steam header pressure transmitter range. is so narrow that safety injection will occur during nonnal cooldown opera-tions unicas the "High. Differential Pressure Between any Steam Line and 2

the Steam Header" signal is blocked. Such a safety injection could result in an uncontrolled cooldown and possible plant overpressurization which is undesirable.

3.0 EVALUATION

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The NRC staff position stated in generic letter of November 28, 1978 required that all licensees " review the design of all safety actu-ation signal circuits which incorporate a manual override feature to j ensure that overriding of one safety actuation signal does not also

cause the bypass (block) of any other safety actuation signal, that j

1 sufficient physical features are provided to facilitate adequate admin-

[ istrative controls, and that the use of each such manual override is annunciated at the system level for every system impacted." It is recommended that the switch which blocks both the " Pressurizer Low Level and Low Pressure" signal and the "High Differential Pressure Between any Steam Line and the Steam Header" signal be modified to

, canply with this staff position.

It is recommended that the proposed change to Table 3.5.3 of the P H. B. Robinson, Unit 2 Technical Specifications to allow blocking the "High Dif ferential Pressure Between any Steam Line and the Steam Header" signal when primary pressure is less than 2000 psig be allowed. Ade-quate protection from a steam line rupture is provided without this signal by independent and redundant systems. Additionally, this will i

prevent inadvertent SIS initiation during cooldown due to the limited range of the Steam Header Pressure transmitter.

4.0 REFE RENCES  ;

1. CPLC letter (Utley) to NRC (Schwencer) dated March 6,1979.

2. H. B. Robinson, Unit 2 Technical Specifications, Table 3.5.3.

3. H. B. Robinson, Unit 2 Final Facility Description and Safety Anal-ysis Report.

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j 4. NRC Mano J. H. Snlezek to D. Eisenhut, dated April 5,1978.  ;

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5. NRC generic letter dated November 28, 1978, Containment Purging l During Normal Plant Operation. ,

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