ML19320B308
| ML19320B308 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 06/12/1980 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML14192A062 | List: |
| References | |
| NUDOCS 8007100162 | |
| Download: ML19320B308 (9) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 47 TO FACILITY OPERATING LICENSE N0. DPR-23 H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-261
1.0 INTRODUCTION
By letter ' dated March 6,1979, the Carolina Power and Light Company submitted proposed changes to the Technical Specifications to allow blocking the "High Dif#erential Pressure between any Steam Line and Steam Header" Safety Injection Signal initiation when the primary reector coolant system is less than 2,000 psig.
Our review of the proposed Technical Specification changes and the associated circuitry follows.
2.0 EVALUATION The enclosed Technical Evaluation report was prepared for us by our consultant EG&G Idaho, as part of our DL Technical Assistance Program.
3.0 CONCLUSION
S Based on our review of the EG&G Idaho technical evaluation, we agree with their finding that the proposed change to Table 3.5.3 of the H.B. Robinson Unit 2 Technical Specifications to allow blocking the "High Differential Pressure between any Steam Line and the Steam Header" signal when primary pressure is less than 2,000 psig be allowed. Adequate protection from a steam line rupture is provided without this signal by independent and redundant systems. Additionally, this will prevent inadvertent SIS initiation during cooldown due to the inmited range of the Steam Header Pressure transmitter.
The NRC staff position stated in generic letter of November 28, 1978 required that all licensees " review the design of all safety actuation signal circuits which incorporate a manual override feature to ensure that overriding of one safety actuation signal does not also cause the bypass (block) of any other safety actuation signal, that sufficient physical features are provided to facilitate adequate administrative controls, and that the use of each such manual override is annunciated at the system level for every system impacted." EG&G 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 include the separation of these bypasses and to comply with this staff position.
We have informed our consultant and they agree that the above staff position relates to actuation signal circuits which incorporate a
" manual override feature." However, the licensee proposed changes 8 0 0 7 010/[a2.;.
9 deal with " operating bypasses" which are defined by IEEE Std. 279-1971, as requiring the design to be such that the bypass will be removed automatically whenever permissive conditions are not met. As such, no modification to the switch which blocks both the " Pressurizer Low Level and Low Pressure" signal and th9 "ufgh Differential Pressure Between any Steam Line and the Sic m header" signal is required.
We a
have reviewed the switch circuitry and conclude that there is adequate physical separation between these two safety injection signals.
Environmental Considerations We have determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact.
Having made this determination, we have further concluded that the amendment involves an action which is insignificant from the standpoint of environmental impact, and pursuant to 10 CFR 51.5(d)(4), that an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
Conclusion We have concluded, based on the consideration discussed above, thati (1) because the amendment does not involve-a significant increase in the probability or consequences of accidents previously considered and does not involve a significant decrease in a safety margin, the amendment does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and this amendment will not be inimical to the common defense and security or to the health and safety of the public.
n te: June 12,1980 a
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1030F TECHNICAL EVALUATION REPORT ELECTRICAL, INSTRUMENTATION, AND (X)NTROL ASPECTS OF PROPOSED TECHNICAL SPECIFICATIONS CHANGE REGARDING BLOCKING OF SAFETY INJECTION SIGNALS WHEN PRESSURE IS BELOW 2000 PSIG H. B. ROBINSON, UNIT 2 Docket No. 50-261 February 19809 S. E. Mays 2/14/80
CDNTENIS 1.0 INIRODUCTION.
i 2.0 DISCUSSION 1
3.0 EVALUATION
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4.0 REFERENCES
3 ii l
TECHNZCAL EVALUATION REPORT ELECTRICAL, INSTRUHENTATION, AND CONTROL ASPECTS OF PRC'.'OSED TECHNICAL SPECIFICATIONS CHANGE REGARDING BLOCKING OF SAFETY INJECTION SIGNALS WHEN PRESSURE IS BELO'J 2000 PSIG H. B. ROBINSON, UNIT 2 1.n INTRODUCTION Th'e 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 then pri=ary 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 aller 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 Table 3.5.3 of the Technical Specifications be changed to allow block-ing the "Hig t Differential Pressure Betwten any Steam Line and the Steem 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 (FSAR) discusses the factors protecting 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 1
l l
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 signal s.
(1)
Pressurizer Low Level and Low Pressure (2) High Diff erential Pressure Between any Steam Line and the steam Header
( 3) High Conttinment Pressure (4) High Steam Flow in 2/3 Stems Lines Coincident with Low T,y 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 vould 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. Tcble 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 ooerability of at least one steam line flow channel per loop, two T avg 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 2000 psig.
Furthermore, as noted in NRC Memo from 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 nonsal cooldown opera-tions unless the "High Diff erential Pressure Between any Steam Line and 2
4
A 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 signals.
(1) Prest,urizer Low Level and Low Pressure (2) High Differential Pressure Between any Steam Line and the Steam Header (3) High Contairunent Pressure (4) High Steam Flow in 2/3 Steam Lines Coincident with Lou T or Low Steam Pressure.
avg 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 avg 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 syt. ems if both aig-nals (1) and (2) above are blocked when the primary pressure is below 2000 psig.
Furthennore, as noted in NRC Memo from 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 normal cooldown opera-tions unless the "High Differential Pressure Between any Staam Line and 2
the Steam Header" signal is blocked. Such a saices injection could resul t in an uncontrolled cooldown and possible plant sverpressurization which is undesirable.
3.0 EVALUATION The NRC staff position stated in generic letter of November 28, 1978 required Jiat all licensees " review the design of all saf ety actu-ation signal circuits which incorporate a manual override feature to ensure that overriding of one safety actuation signal does not also cause the bypass (block) of any other safety actuation signal, that sufficient physical features are provided to f acilitate adequate admin-istrative controls, and that the use of each such manual o.erride is annunciated at the system level for every system Lapacted." It is recommended that the switch which blocks both the " Pressurizer Low Level and Low Pressure" signal and the "High Differential Pressure Between any Steen Line and the Steam Header" signal be modified to comply with this staff position.
It is reconmended that the proposed change to Table 3.5.3 of the H. B. Robinson, Unit 2 Technical Specifications to allow blocking the "High Differential 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 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 (Cahwencer) 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-
{
l ysis Report.
3
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4 4.
NRC Memo J. H. Sniezek to D. Eisenhut, dated April 5,1978.
5.
NRC generic letter dated November 28, 1974, Contairznent Purging During Normal Plant Operation.
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