ML20207D168
| ML20207D168 | |
| Person / Time | |
|---|---|
| Issue date: | 03/16/1983 |
| From: | Rubenstein L Office of Nuclear Reactor Regulation |
| To: | Mattson R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20151H089 | List:
|
| References | |
| FOIA-88-92 NUDOCS 8808150278 | |
| Download: ML20207D168 (4) | |
Text
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MAR 161983 MEMORANDUM FOR: Roger J. Mattson, Director Division of Systems Integration.
1 FROM:
L. S. Rubenstein, Assistant Director for Core and '
Plant Systems, Division of Systems Integr'ation
SUBJECT:
REVISION TO STATEMENT OF STAFF POSITION REGARDING SOURCE RANGE FLUX, REACTOR COOLANT TEMPERATURE, AND STEAM GENERATOR PRESSURE INDICATION TO MEET APPENDIX R By memorandum dated January 7,1983, we documented the need for source range l ?"'
flux, reactor coolant temperature, and steam generator pressure indication at an alternate location (remote to the control room). That document was requested by DL in anticipation of the need to issue orders to some of the I
licensees to obtain compliance with Appendix R.
Since that time, those utilities which obtained copies of our January 7,1903 memorandum, provided feedback with respect to plant specific considerations, among them, the use of exit core thermocouples.(ECTs) versus hot leg tempera-ture RTD's.
In addition, we have consulted with various personnel at the Chattanooga Reactor Training Center regarding the staff position h result of these discussions, we conclude that the use of ECTs is an acceptable f
alternative to the use of hot leg temperature RTDs.
w Enclosed is the revised staff position regarding the acceptability of ECTs.
Other changes are principally editorial in nature.
t W '. S. t h e & M L. S. Rubens.tein, Assistant Director for Core and Plant Systems Division of Systems Integration Enclosure :
As stated
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l Staff Position _
l Section III.L.1 of Appendix R to 10 CFR 50. requires that alternative shut capability shall be able to achieve and maintain suberitical reactivity Section III.L.2 of Appendix R to 10 CFR 50 conditions in the reactor.
requires provision for direct readings of the process variables necessary to perform and control the reactor shutdown function.
source range Among the process variables which are to be monitored are: These l
flux, reactor coolant temperature, and steam generator pressure.
three have been controversial so we have set forth our basis for conclu that they are necessary in order to meet Section III.L of Appendix R.
Source Range Flux _
Monitoring of core flux provides a direct indicaticn of the reactor shutdo The monitoring of other process' variables would provide an With regard to the fission process, changes in condition.
neutron flux provides the quickest means of assessinq inferred answer only.
valves could result in power excursion which would not be readily dete conditions.
'i by interpreting the changes in other process variables (such as rea coolant temperature or pressure).for boron concentration is co Additionally, should the cperators fail te detect a loss of negative reactivity in a timely manner, the boron requirements.
Thus, the provision for post fire source range be unavailable due to fire. flux monitoring is necessary to meet Secti Reactor Coolant Temperatures The reactor coolant temperatures, in conjunct The and control and, hence, conformance with Section III.L.2 of Appendix R plant control elements which rely on accurate reac concerns.
In the natural circulation mode of operation, the hot leg temperature, cold leg ternperature and the d Natural Circulation:
(1) hot leg and cold leg temperatures, (T In order to verify natural circulation conditions can be determined.th require the operator to use cold leg temperatur 3
I The staff side steam generator pressure Tsat, will approximate T.
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acknowledges that such a condition can exist if natural circulation isCool I
occurring; however, the converse cannot be asstaned. ach Due to the inherent auxiliary feedwater flow to the steam generators.
cannot be lag in response between the secondary and primary side, TNatura inferred from T that T and are constant or decreasing, knowing T T,sMs.ervin andbymobtofing(To-Tj. SinctnorTaf controi room procedures the use of Te in conYirsing natural circulation, emergency proceduresT should not diviate from this practice. wide range indication is necessary for cold leg temperature. Tc Section III.L.2 of Appendix R.
(2) Upper Vessel Voiding:
(Deleted)
Subcooling: The bulk fluid temperature TH provides a reliable indication of the degree of RCS subcooling when used in conjunction with the RCS (3) is also used as a means of verifying natural circulation.
pressure. Tg It has been suggested that exit core thermocouples (ECTs) provideECT i
temperature indications equivalent to 7.
temperature conditions above the core, $nd can give 1
equivalent T since ECT readings are dependent not only upon radial positioning, but g
Thus, the provision for wide also local flow rates past the ECTs.
loop RTDs for range ECTs is an acceptable alternate to wide range Tu f
l, meeting Section III.L.2 of Appendix R, provided th temperature readings representative of Ty.
demonstrate that under conditions where the reactor vessel upper hea void is expanding thus, bringing' highifteiipera'tuie'lluid.into the outlet --
plenum and hot legs, the' ECTs give a conservative indication of outlet plenum temperature.
T in con-Pressurized Thermal Shock and Appendix G' Considerations:
junction with the RCS pressure, provides a direct indicatiob, (4) plant condition relative to the plant's pressure / temperature limits as i
it pertains to the Pressurized Thermal Shock considerations and the low temperature overpressure protection as outlined in Appendix G of Due to the collective effect of the steam generator con-ditions (i.e., feedwater flow and steam generator pressure) on the 10 CFR 50.
primary coolant temperatures, and the inherent lag beteen the seco and primary sides conditions especially during transient conditions, may not be accurately inferred from the secondary side steam T
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conditions.
I Steam Generator Pressure _
f During non-power modes of operation, "control" is e
procedures is pressure) to compensate for variances in primary system
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Maintenance of level in the steam generators may not be a "hot standby" or "hot shutdown" mode, or tra performance.
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Improper pressure control may cause an imbalance in heateremoval which.could result in excessive depre mode to "cold shutdown" mode.
the result of which could be generation of an undesired bubble in the i
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primary system (e.g., upper head for all PWRs or candy cane or rapid cooldown and potential for violation of vessel pressure /
For the monitoring of secondary sy(stem heat removal,
- Thus, level inventory),andpressure.
limits.
system parameters should be known: provisions for post fire st i
l necessary for meeting Section III.L.2 of Appendix R.
Instrumentation Guidelines _
Section III.L.6 requires that, "Shutdown systems installed to ensur fire shutdown capability need not be designed except where.for required for other reasons *, e.g., because of int lve with or impact on existing safety systems, or because of adverse v actions due to fire damage."
f meters need not be "safety grade" in order to meet the requirements o 7
Appendix R.
i Section III.S.3 requires that, "Alternate or dedicated shutdown ca and its associated circuits, independent of cables, systems or comp For a in the area, room or zone under consideration, shall be provided."
h postulated fire, an electrically independent monitoring capabilit above listed parameters should be provided outside the control room.
Based on the above, the revised list of instrumentation needej pressurizer. pressure and. level, reactor coolant hot leg t a) b)
cold leg temperature, steam generator pressure and level (wide range),
c) source range flux monitor, diagnostic instrumentation for shutdown systems, and d) level indication for all tanks used (e.g., CST).
e) f)
The instrtnentation needed for BWRs is unchanged, m
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