ML16342A509
| ML16342A509 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 05/10/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML16342A508 | List: |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 NUDOCS 9405190072 | |
| Download: ML16342A509 (8) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION CONFORMANCE TO REGULATORY GUIDE 1.97 PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON NUCLEAR POWER PLANT UNIT NOS.
1 AND 2 DOCKET NOS.
50-275 AND 50-323
1.0 INTRODUCTION
In a submittal dated February 17,
- 1993, the licensee documented deviations to Regulatory Guide (R.G.) 1.97, Revision 3, not previously identified.
On February 4, 1994, the staff issued a Safety Evaluation (SE) regarding the licensee's conformance to R.G. 1.97.
The staff found the licensee's design for post-accident monitoring instrumentation acceptable.
However, while the SE was being prepared, the licensee documented additional deviations to R.G.
1.97 in a letter dated December 17, 1993.
Resolution of these deviations is discussed below.
2.0 EVALUATION We have reviewed the licensee's December 17,
- 1993, deviations and exceptions with regard to:
(1)
RCS temperature, (2) steam generator wide range level, radiation, (4) steamline
- pressure, (5) containment (6) neutron flux, and (7) Type A instrumentation.
below.
submittal which identified hot and cold leg (3) main steamline isolation valve position, These issues are discussed (1)
The licensee has provided Category 1
RCS hot and cold leg temperature instrumentation in conformance with R.G.
1.97.
In addition, an environmentally qualified RCS temperature selector switch has been provided to select either loop 1
RCS hot leg temperature or loop 1
RCS cold leg temperature for display on a non-Category 1 indicator located on the PDS panel (a dedicated remote shutdown panel).
When the switch is not set to indicate either hot leg or cold leg temperature, the switch is set to the "calibrate" position.
This switch is only used for temperature indication during remote shutdown from ':
outs.ide the control room.
In the "calibrate" position, the switch contacts isolate the Category 1 portion of the circuit from non-Category 1 instrumentation.
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(2)
(3)
We have reviewed the isolation provided by this switch and have determined that this switch provides adequate isolation of the Category 1
portion of the circuit from non-Category 1 instrumentation.
Therefore, we find the existing RCS hot and cold leg temperature instrumentation acceptable.
R.G.
1.97 recommends Category 1 steam generator wide range level monitoring instrumentation.
The licensee has committed to modify the steam generator wide range level instrumentation des'ign such that two of the four instrument loops will be powered from a separate vital AC power source.
However, this new design will not change the physical separation of instrument signal cables.
This is a deviation from the Category 1
criteria, but, the licensee has adequately justified this deviation.
The licensee previously documented that a separate future modification was being considered that would provide a second power source to all control channels.
The licensee has not made a commitment to this enhancement.
This enhancement would provide power supplies for the steam generator wide range level instrumentation that would be in excess of the R.G.
1.97 recommendations.
Therefore, if the licensee chooses to proceed with this enhancement, NRC review for R.G.
1.97 purposes would not be necessary.
R.G.
1.97 recommends Category 2 instrumentation to monitor releases from steam generator safety relief valves or atmospheric dump valves.
The licensee has provided Category 2 main steamline radiation monitors to detect radiation releases from the main steamline.
The main steamline radiation information is recorded by an isolated Category 3 multi-channel recorder.
The main steamline radiation information is also recorded by the Emergency
Response
Facility Data System (ERFDS) and the Emergency Assessment and
Response
System (EARS).
The ERFDS and EARS (although not classified as Category
- 2) are highly reliable and are designed to be used to monitor the course of an accident.
Therefore, the use of the multi-channel
- recorder, ERFDS, and EARS to record main steamline radiation information is acceptable.
The licensee has determined that steamline pressure monitoring is required for manual action for which no automatic action is provided.
Therefore, this instrumentation was identified as Type A and it meets the Category 1 criteria except for recording.
The steamline pressure information is input to the plant process computer and ERFDS, which are not Category 1 systems.
The use of isolated non-Category 1 recorders and-computers is acceptable for recording Category 1 information.
Therefore, the use of the plant process computer and ERFDS to record steamline pressure information is acceptable.
R.G.
1.97 recommends that containment isolation valve position indication meets the Category 1 criteria.
The licensee has committed to upgrade the existing indication system to meet the Category-1 criteria except for physical separation of instrument signal cables between.logic panels and control room white light boxes, within the white 'fight boxes, and between the white light boxes and the white light test switches.
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c The licensee has committed to perform a failure modes and effects analysis to demonstrate that a single active failure would not'ause the loss of both inboard and outboard white light indicators for the same penetration.
Therefore, the licensee's upgraded design for containment isolation valve position indication is acceptable.
(6)
R.G.
1.97 recommends Category 1 neutron flux monitoring instrumentation and the licensee has provided Category 1 instrumentation in the control room.
The licensee also previously documented that the neutron flux information displayed in the Technical Support Center (TSC) and the Emergency Operations Facility (EOF) would be from Category 1 sources but recently indicated that this information would not be provided from Category 1
sources.
Although, this is not a deviation from the R.G.
1.97 recommendations, it is a change in a commitment.
This change in commitment is acceptable.
(7)
The licensee has revised the list of Type A instrumentation and has removed neutron flux from its list.
The list is as follows:
Containment Pressure (Normal Range)
Reactor Coolant Outlet Temperature T (Wide Range)
Reactor Coolant Inlet Temperature - T, (Wide Range)
Reactor Coolant Pressure - Wide Range Pressurizer Water Level Steamline Pressure Steam Generator Water Level - Narrow Range Steam Generator Water Level - Wide Range Refueling Water Storage Tank Water Level Containment Reactor Cavity Sump Level - Wide Range Containment Recirculation Sump Level Narrow Range Auxiliary Feedwater Flow Rate In Core Thermocouples Condensate Storage Tank Level.
The licensee has provided adequate justification for this revision.
This instrumentation either meets or has been granted deviations from the Category 1 criteria.
However, the staff prefers an approach where the Type A and other Category 1 instruments would be included in the accident monitoring section of the technical specifications.
3.0 CONCLUSION
Based on our review of the licensee's submittal, the staff concludes that the licensee has provided adeqppte justification for deviations from and exceptions to R.G. 1.97, Revision 3 for instrumentation that monitors (1)
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hot and cold leg temperature, (2) steam generator wide range level, (3) main steamline radiation, (4) steamline
- pressure, (5), containment isolation valve
- position, (6) neutron flux, and (7) Type A variables.
Princi al Contributor:
B. Marcus Date:
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