ML20114D309
| ML20114D309 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 01/18/1985 |
| From: | Musolf D NORTHERN STATES POWER CO. |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 NUDOCS 8501310193 | |
| Download: ML20114D309 (6) | |
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Northern States Power Company 414 Nicopet Mad Minneapo:rs. Minnesota 55401 Toleonone (612) 330 5500 January 18, 1985 Director Office of Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 Additional Information Related to Conformance With Regulatorv Guide 1.97, Revision 2 The purpose of this letter is to provide, for the infomation of the NRC Staff, additional information related to confomance to Regulatory Guide 1.97, Revision 2, " Instrumentation for Light-Water-Cooled Nuclear Power Plants to Assess Plant and Environs Conditions During and Following an Accident." This infomation was requested in a letter dated December 4, 1984 from James R Miller, Chief, Operating Reactors Branch #3, Division of Licensing, USNRC.
The following infomation is provided in response to Mr Miller's December 4,1984 letter:
- 1. For those variables listed in Section 3.3.1-environmental qualification should be addressed in accordance with 10 CFR 50.49.
Response
Post-accident monitoring instrumentation wi31 be addressed by,ur 10 CFR 50.49 review program. Documentation supporting the % vel of environmental qualification required for this mstrumentation will be part of our environmental qualification documentation file.
- 2. Containment hydrogen concentration-the licensee should show that the sensors are capable of operating at sub-atmospheric pressures (Section 3.3.6).
Response
A temperature-pressure profile for qualification of inscrumentation in a post accident vacuum condition has not previously existed. We are working with other utilities and the vendor to establish O
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s' Northem States Power Company l
Director of NRR i~
January 18, 1985 Page 2 the qualification profile and perform the qualification testing.
The vendor anticipates no problems in qualification once the profile is established. Qualification at 10 psia is expected to
'be completed by July 1, 1986.
- 3. Containment effluent radioactivity--noble gases from identified release points--the licensee should provide justification for the deviation in the range supplied (Section 3.3.7).
-Response This. item,:as well as items (5) and (15), concern R-22 and R-50 on the Unit I and Unit 2 Shield Building Vents.
The Technical Specification minimum sensitivity is specified as 1.0 E-4 microcuries/cc. In practice, a sensitivity of 1.0 E-5 microcuries/cc is achievable.
t AtElevels of less than 1.0 E-5, there is no significant release taking place. This is well below Technical Specification limits; for routine operation. At this level there is no concern related to monitoring of accidental releases.
r Grab samples are taken during' normal operation. These staples
'have a minimum-sensitivity in the 1.0 E-8 microcuries/cc
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- range. Grab sampling is the alternative monitoring method.
The installed instrumentation has eight decades of response.
We have chosen to shift the range of this equipment two decades
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higher than the guidance provided in the Regulatory Guide to
. optimize accident monitoring. It should be noted that th~s~e~
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- instruments monitor the-sole accident relases point in each' unit. All accidental releases are collected and' released through a single vent for each unit.
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74.; Radiation exposure rate--the licensee should either cammit to : install instrumentation for this variable that meets Regulatory Guide l.97 recommendations or provide acceptable justification for not doingJso (Section 3.3.8).
J
' Response i
We have. completed.a study of plant radiation levels under accident conditions. Approximately thirty instruments will-be installed throughout the. plant. Range will satisfy the 1.0E-1 to 1.0E+4 I R/hr requirement of: Regulatory Guide 1.97.
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..4 Northem States Power Company Director of NRR January.18, 1985 Page 3-Equipment has not yet been procured. The system will use-equipment being installed for the new plant process computer.
- 5. Effluent radioactivity-noble gases inside buildings or areas where penetrations or hatches are located-the
. licensee should show that the two decades of range from
.E-6'to E-4 microcuries/cc are not needed for the detection of breach (Section 3.3.9).
-Response See. item (3) response above.
- 6. Accumulator tank level-the licensee should supply additional -
justification for the devi tion for this variable (Section 3.3.11).
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Response
.The acetsnulator level-instrumentation range is based on Technical Specification. requirements. The volume of each accumulator is 2000 cubic feet.. The Technical' Specifications require that the volume be maintained.between 1250 and 1289.9 cubic feet.-
To
'accomodate this requirement, the level instruments are ranged between 1235.25 and 1295 cubic feet..This corresponds to 0 and 100% on the indicators.-
, Proper operation-of the accumulator under accident conditions is confirmed by'the. operator using a combination of the level Din'dicators going off scale low and pressure indicators falling with reactor coolant system pressure.
o 7.- Pressurizer heater status-the licensee should install Category 2 instrumentation to monitor the heater status (Sections 3.3.14).
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- ' Response
" ; Pressurizer' heater status s' indicated by: lights that are part of the control switch module for each heater bank, on the main, control board.' 'These' lights indicate whether the Theaters-are on,'off, or.if the' source breaker for the bank s
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.has-tripped:on overload. This? installation satisfies the
- requirements of NUREG.0737, Item II.E.3.1.
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'; The functional guidance specified in Regulatory Guide 1.97 'is "to determine' operating status.". The switch module lights, in
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. conjunction with-other indicators of 480 VAC bus ~ status, a_
provide indication that power is available tc the heaters.
- Indication.of subcooling margin,.using the subcooling margin
' monitors, provides assurance that the heaters are performing.
their function.-' Measurement of heater current is not needed.
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Northem States Power Company Director of NRR January 18, 1985 Page 4
- 8. Quench tank temperature--the licensee should provide additional justification for the 0 to 360-F range (Section 3.3.15).
Response
The pressurizer relief tank temperature instrumentation will be re-ranged to O to 350-F.
This will cover the saturation temperature corresponding to the rupture disc relief point.
- 9. Steam generator level--the licensee should provide redundant channels of instrumentation for each steam generator.
Response
Steam generator instrumentation consists of four channels of level indication for each steam generator. There are three narrow-range channels and one wide-range channel. The narrow-range channels are used both for indicating protection functions and in the automatic control system. The wide-range channel is used for indication only.
The adequacy of this installation was previously reviewed and found acceptable by the NRC Staff in their evaluation of conformance to the requirements of NUREG-0737, Items II.E.1.1 and II.E.1.2 (auxiliary feedwater system adequacy). Refer zto a letter dated March 22, 1982 from R A Clark, Chief, Operating
. Reactors Branch #3, Division of Licensing, USNRC and the attached-Technical Evaluation Report, TER-CS257-278/291.
- 10. Auxiliary feedwater flow--the licensee should either re-range this instrumentation or provide justification for the deviation from the recausended range (Section 3.3.17).
Response
Auxiliary.feedwater pump flow indication will be reranged to O to 250 GPM to' comply _with the Regulatory Guide 1.97, Revision 2,. recommendation.
- 11. Condensate storage tank level--the licensee should clarify the seismic qualification applied to this instrumentation, and justify any portion not qualified (Section 3.3.18).
Response
Condensate storage tank level indication will be seismically
- qualified for both new and existing channels.
4 Northem States Power Company Director of NRR-January 18, 1985 Page 5
- 12. Containment spray flow-the licensee should install' the recommended instrumentation for this variable (Section 3.3.19).
Response
In the EG&G review document, it is argued that containment parameters alone will not monitor the operation of the containment spray system since a containment fan heat removal system is also utilized at Prairie Island. It has been the NSP position that the effectiveness of containment heat removal systems is best measured by the containment
- parameters themselves (primarily containment pressure).
It should be noted :that during the injection phase of ECCS operation.
RWST and' caustic standpipe level are indicators of containment
. spray pump operation. Pump and valve status are also available in the control room.. This capability, combined with the direct monitoring of containment parameters, is judged to be adequate.
The additional benefit to'be gained by installing containment
. spray flow instrumentation is not balanced by the cost involved.
- 13. Containment sump water temperature-the licensee should provide the range and category of the alternate instrumentation used
.for this variable.
Response
RHR heat exchanger outlet temperature is available for monitoring
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the effectiveness of reactor and containment heat removal in the
-long-term recirculation mode of:the ECCS system as noted in Section 3.3.10.
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RHR heat exchanger inlet temperat'ure instrumentation is provided at Prairie Island, but it is located outside of the flow path used in the recirculation mode. It is useful only for normal operation of the RHR system in the shutdown cooling mode. No credit can be.taken for this instrumentation.
'As noted in our response to: item (12) above however,-it.'is our-position that the effectiveness of containment heat removal-systems.is best measured by the: containment paramerters themselves.
The~ fact that heat < exchanger outlet temperature is monitored
- as well as containment parameters leads us to believe that there is little benefit to be' gained-in installing sump temperature
' instrumentation.
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Northem States Power Company Director of NRR January 18, 1985 Page 6
- 14. Radioactive gas holdup tank pressure-the licensee should verify that the existing local instruments have a range of 0 to -150 percent of design pressure (Section 3.3.22).
Response
The gas decay tanks are provided with pressure gauges having a range of-0 to 150 psig. The vaste gas compressors have a maximum discharge pressure of approximately 100 psig. The gas decay tank design pressure is 150 psig.
Since the waste gas compressors can only pressurize the tanks to about 100-psig, we believe the range of the instrumentation is satisfactory.
- 15. Reactor shield building annulus-noble gas level and vent flow rate--the licensee should provide satisfactory justification for the range deviation (Section 3.3.23).
-Response 4
See_ item _(3) response above.
- 16. Plant and environs radiation--the licensee should provide satisfactory justification for their deviation from the maximum recommended range for Beta particles (Section 3.3.25).
J
Response
~ We now have one portable instrument'with an upper range of 19.9 K R/hr' beta. The range suggested in Regulatory Guide 1.97, Revision 2, is now covered.
~ Please contact us if you have any questions related to the additional infomation we have provided. We believe we have satisfactorily addressed all of the open items noted in Mr Miller's December 4, 1984 letter with the exception of a few items in which there is still some technical disagreement over_the benefit to be gained by installing certain new instrumentation. We would like the opportunity to discuss these items in further detail with the Staff.
D David Musolf Manager - Nuclear. Support rvices
- cc: Resident Inspector, NRC Regional Administrator-III, NRC NRR Project Manager, NRC G Charnoff
-