ML20212J354
| ML20212J354 | |
| Person / Time | |
|---|---|
| Site: | MIT Nuclear Research Reactor |
| Issue date: | 06/24/1999 |
| From: | Bernard J, Hu L MASSACHUSETTS INSTITUTE OF TECHNOLOGY, CAMBRIDGE |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-M99844, NUDOCS 9906290317 | |
| Download: ML20212J354 (18) | |
Text
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NUCLEAR REACTOR LABORATORY (\ ) /
AN INTERDEPARTMENTAL CENTER OF >
MASSACHUSETTS INSTITUTE OF TECHNOLOGY JOHN A. BERNARo 138 Albany Street. Cambndge, MA 02139-4296 Actwation Analysis ovector Telefax No. (617) 253 7300 Coolant Chernistry Director of Reactor operabona Tel. No. (617) ""C'**'""*"*
253 4 202 Pnncipal Research Engineer - Reactor Engineenng June 24,1999 Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555
)
Subject:
Massachusetts Institute of Technology Research Reactor, Docket No. 50-20, License No. R-37, Response to TAC NO. M99844 Gentlemen:
Enclosed is our response to TAC NO. M99844.
We have answer all questions in exception of questions 12 and 13. A separate amendment has been submitted to address question 12. A separate amendment has been prepared to answer question 13 and it will be submitted within about a week.
The enclosed material has been reviewed and approved by the MIT Committee on Reactor Safeguards. Please direct any question to the undersigned.
Sincerely, 5
Lin-Wen llu, Ph.D.
Reactor Relicensing Engineer r( 4 ohn A. Bernard, Ph 9906290317 990624 Director PDR ADOCK 05000020 P PM (} g 1p l
JAB /lwh cc: USNRC - Senior Project Manager, NRR/ONDD USNRC - Region 1 - Project Scientist Eflluents Radiation Protection Section (ERPS)
FRSSB/DRSS s0
_ __ _ _ _ _ _ l
t Response to Request for AdditionalInformation Massachusetts Institute of Technology Docket No. 50-20; License No. R-37 (TAC NO. M99844)
June 24,1999
)
- l. Section E in our answer to question # 28 of January 14, 1999 is amended to provide information comparable to that given in sections A, B, C, and D. Manual opening of the fission converter medical room shield door is added to the list.
Section E now reads as follows:
" E. Emergency Manual Controls El. Manual Closing of the Mechanical Shutter E2. Manual Opening of the Fission Converter Medical Room Shield Door"
- 2. Routine operation of the fission converter does not require the presence of a senior reactor operator. An event such as fuel movement is governed by the existing MITR fuel transfer procedure that requires the presence of a SRO. That procedure will be expanded to include the fission converter. Fission converter operations that involve the CCS during the initial startup testing will also require the presence of a SRO.
- 3. Both the reactor scram and CCS automatic closure for low primary flow should be bypassed during low power / natural convection operation because, as shown in Table 7.1 (page 7-4) of the SER, a loss of forced convection results in both a scram and automatic CCS closure.11ence, both need to be bypassed for natural convection.
- 4. The proposed design for the CCS consists of a layer of Cd followed by a layer of Boral or Boralyn. Both Boral or Boralyn are boron-aluminum compounds. The Cd would remove thermal neutrons and the Boral will remove epithermal ones as well as some thermal ones. This is the reason for the two layer design. The Cd layer is placed in front so that it is closest to the reactor and hence there will be less heating of the Boral. Currently no cooling system is designed for the CCS.
Tests were made to measure the anticipated temperature of this shield. In February 1998 a temporary lead shield was installed in the fission converter space. This shield was 8" thick, and was clad on both sides by a layer of cadmium with an outer layer of steel. On the front (reactor) side, positioned adjacent to the aluminum window (region of maximum flux) was a 15 inch square piece of 1/4" boral with a 20 mil cadmium layer in front. This was intended to simulate the design of the converter control shutter. Afler the installation, the reactor was operated up to 4.8 MW and temperatures were measured at several locations.
These included locations at the cadmium-boral interface as well as in the interior of the lead itself. Temperatures were taken over a variety of reactor operating and coolant flow conditions over the course of approximately one year. The largest temperature recorded was 126 C at the Cd-Boral interface. This is well below the -
320 C melting point of cadmium and the 450 C soflening point of aluminum. A cooling coil was installed in the 8" thick lead slab. Ilowever, that coolant flow to the shield had only a minimal influence on the Cd-Boral temperature. The largest temperature recorded in the lead interior was 66 C. Coolant flow did, of course, afTect the lead temperatures, but even an experiment in which coolant flow was completely shut oft did not result in a large increase in temperatures. Using the maximum recorded temperature of 126 C at 4.8 MW, the maximum temperature 1
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- i ,
- . ~%
at the Cd-Boral interface at 10 MW is calculated to be 232 C. This is well below the 320 C melting int of cadmium.
A thermocouple wil! be installed on the CCS during the initial startup testing.
The CCS temperature will be measured and calculations will be made to determine its maximum equilibrium temperature for 10 MW MITR operations.
- 5. The meenanical shutter is driven by an electric motor connected to a ball screw. ,
The shutter is interlocked so that it will be driven closed in the event at the {
medical door being opened or the control panel being switched to the "off" )
position. The shaft to the bal! screw penetrates the shield wall where a hand crank is located for manual closure in the event ofloss of shutter power. About thirty turns are required to manually close the shutter. It should also be noted that in the event ofloss of electrical power, the reactor will scram and the water shutter will automatically close. Should the shutter somehow jam, patient irradiation can be halted by closing the CCS and water shutters or by use of the manual reactor scram button on the medical control panel.
- 6. Administrative controls will preclude this type of accident. These controls are:
(a) All fuel movements are listed in a written schedule that must be apprnved by the reactor superintendent prior to commencement of the evolution.
(b) Copies of the schedule are given to the SRO in charge, the reactor radiation ,
protection person, and the console operator. All three are required to be present for refueling and all three are required to concur on any given move prior to the conduct of that move.
(c) The schedule explicitly lists the elements to be moved by number, current location, and planned location. Moves that are not scheduled are not allowed. ;
(d) Only one fuel element can be moved at a time and it requires about forty-five minutes (estimated) to nove an element into the fissioa converter.
- 7. The discussion of the impact of a step reactivity insertion into the MIT on the fission converter was based on the result of a recently analysis. This analysis concluded that the step reactivity limit insertion is .6% aK/K ($2) with natural convection cooling. The third paragraph of section 6.2 is re-written and now reads as follows:
" The MITR-II SAR calculated the step reactivity limit from a correlation derived from the SPERT experiments. A step reactivity limit of 1.8% AK/K was calculated using that correlation for the MITR to prevent core damage. As part of the MITR relicensing etTort, an analysis was recently made using the PARET code. The reactor power, integrated energy generation, fuel, and coolant temperatures were calculated as a function of time. It was concluded that the most limiting scenario is that the reactor is in a low powec and low flow rate initi.tl condition. The transient terminated because of the large reactivity feedback from voiding within a few tenths of a second. The insertion of the shim bank in 2
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e 1 .. . c 1 .
about a second prevents a power oscillation at a later stage of the transient that might otherwise occur because of a positive reactivity feedback from void collapse. The length of the delay time does not affect the maximum power during this transient. This is because the power excursion occurs within a few tenths of a second, which is far shorter than the blade drop time (less than a second).
It was found that the maximum allowable step reactivity insertions are 1.6% AK/K (or $2) for natural convection cooling and 2.4% AK/K (or $3) for forced convection cooling. The actual figure specified for a limit for the MITR-il is 1.8% AK/K. For the MITR-Ill, limits of 1.2% AK/K for natural convection and 1.8% AK/K for forced convecdon have been proposed. These figures are conservative.
As far as the fission converter is concerned, the relevant quantity is the total energy generated. This is because the fission converter power is controlled by the thermal neutron flux coming from the MITR core and that flux is proponional to the MITR power. The fission converter power is about 2.5% of that of the MITR (250 kW/10 MW=0.025). Therefore, the power deposited in the fission converter would be 2.5% of ihat in the MITR. Assuming all the energy is deposited in the fuel plates and neglecting heat transfer to the coolant, the maximum fission converter fuel temperature would reach 138 C if a step reactivity insertion of 1.6% AK/K (or $2) occurred in the MITR That insertion is the limiting scenario for the fission converter because it produces the greatest integrated energy."
- 8. Figure 6.9 shows two temperatures. The mixing area coolant temperature is measurable. The average primary coolant outlet temperature, which is not measurable, can be inferred by correlation such as is shown in Figure 6.9. We think that confusion may have arisen because of the last sentence of the first paragrsph of section 6.5 of the SER. That sentence should read: " The average primary coolant outlet temperature will be higher than the mixing coolant temperature during this transient because of this mixing effect." In addition, we have re-written the last paragraph of SER section 6.5. It now reads: " Figure 6.9 shows the calculated average primary coolant outlet temperature and the mixing area (upper fission converter tank) temperature. The rise in the outlet temperature during the first 10 seconds is the esult of the reduced primary fiow. The calculation indicates that the average primary coolant outlet temperature stans to decrease aller about 30 seconds. This is the result of a decreasing primary coolant inlet temperature as shown in Figuie 6.10. Both the primary coolant temperature and the mixing area coolant temperature ,pproach a new steady-state operating condition in about 300 seconds. The primary coolant outlet temperature reaches a maximum of about 60 C (or 10 C higher than the mitial steady-state primary coolant outlet temperature). As shown in Figure 3.8, incipient boiling will not occur until the primary coolant outlet temperature reaches 71 C (at 250 kW).
Therefore, incipient boiling will not occur daring this transient."
- 9. Section 6.9 has been revised. It now states that: " Experiments may be conducted in the fission converter provided that they comply with ( .: ting MITR Technical Specifications that govern samples. These are enumerate; in Section 5.5 of this l
3 1 1
d '
.~.
SER. In addition, each type of experiment would be required to have its own safety evaluation. This approach is currently followed for all in-core facilities in the MITR. The individual SER would address possible malfunctions. These evaluations are subject to review by the Reactor Operations StafT and the MIT Reactor Safeguards Committee."
- 10. (a) The safety limits are calculated for several coolant heights as was done in the MITR-il SAR. The approach of having more than one coolant level provides a wider range of combinations of the power, flow rate, temperature, and coolant height that form the safety limits. The three coolant levels used in the safety limits calculations correspond to the coolant level during normal operation (2.6 m), LSSS coolant level (2.1 m),
and the coolant outlet pipe entrance (1.6 m).
(b) The LSSS for coolant height (H) for natural convection cooling has been changed to 2.5 m to provide a margin to the safety limit.
(c) To supplement Appendix G to our response dated January 141999, mor:
information for each LSSS for both operational modes is provided. This material is contained in a new appendix, which is labeled Appendix 1 and is included with the present submission.
- 11. TS Table 6.6.2.5-1 inadvertently reversed the entries concerning power for operation with and without forced convection flow. The corrected table is attached. The footnote itselfis correct except it was referring to the wrong case.
Also the coolant height for natural convection cooling is changed to 2.5 m as explained in item 10(b).
- 12. A separate amendment has been requested from NRC to correct this error.
- 13. A separate amendment will be submitted to address this matter.
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l CHANGES TO THE FISSION CONVERTER SER 1
4 Notice that the LSSS temperature calculated for 300 kW and 45 gpm is 63 C (see Figure 3.8).
3 The calculated LSSS for natural circulation operation coincides with the result of the safety limits (Figure 3.7). The reason for this is as follows. For natural circulation, both the heat flux and flow rate am low. Hence, the axial coolant temperature rise exceeds the '
film temperature rise (radial direction). This difference is exacerbated when the engineering factors ar'e applied. The net effect of the dominance of the axial coolant temperamre rise is that the maximum coolant temperature and the maximum fuel clad utmperature ;
simultaneously approach the saturation temperature. It is worth noting that ONB does always occur before OSV and, if were not for the application of the engineering factors, -
this difference would be apparent for the above calculation. Therefore, a 5 C margin is l added to establish the LSSS curve to allow adequate response time for appropriate actions.
The LSSS coolant height is set at 2.5 m. The resulting LSSS curve is shown in Figure 3.9. This added margin corresponds to about six minutes of heat up in the mixing area with the fission conveiter power at 20 kW. The following limiting safety system settings are chosen for the fission converter with natural circulation:
Variable Limitine Safety System Settine P 20 kW (max)
Tmix 60 C(iaax) i H 2.5 m above top of fuel elements (min) l l
l Notice that the LSSS temperature corresponding to 20 kW at natural circulation is 63 C (see Figure 3.9). j h
l Analyses for both forced convection and natural convection have been perfomied which show that the margins are adequate. Namely, the margins are sufficient so that j automatic protective actions will correct an abnormal situation before a SL is reached.
3-28 l
~-
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- . l j
j 40,,,%,,,,,,,,,,,,,,,,,,,,,,,,,,,,.
35 + + - - - - + - H , 2.5 m --
30 l +-
i j
g a 25
+ --+
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20 --- -
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15 ---
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10 l 35 40 45 50 55 60 65 70 75 Tmix( C) !
l l
l Figure 3.9 Fission Converter LSSS for Oneration with Natural Convection (for eleven fuel cleraents only) 3-30
n l6 '. :
shutter is emptied, the tank will be filled with air or hehum. Calculation has shown that the 41 Ar production is insignificant _[Ref. 4-2]. It is desired that the normal opening and closing time be less than 120 secony However, there is no safety significance to this number. The 120 second figure is chosen solely for reasons of efficient operation.
Interlocks an: provided to ensure that the water shutter closes automatically when the l
medical room door is open or the medical room control panel keyswitch is turned to the OFF position.
l 4.1.2.2 Mechanical Shutter t
A fast-acting mechanical shutter composed of lead and a hydrogenous material such as polyethylene will be located at the end of the collimator closest to the irradiation position to provide shielding from both gamma radiation and fast neutrons. The mechanical shutter will be operated by an electric motor connected to a ball screw. The shaft to the ball screw penetrates the shield wall where a hand crank is located for manual closure in the event of loss of shutter power. About thirty turns are require.2 to manually close the shutter. Limit switches are used to indicate the mechanical shutter position (full closed or full open) at the medical control przel. Interlocks are provided to e'nsure that the mechanical shutter closes automatically when the medical room door is open or the medical room control panel ke$ switch is turned to the OFF position.
- , It is desired that the opening and closing time for this shutter be less than a few l . seconds. This is desired so that patient exposurc to the beam will start and stop in a step-like manner. However, a ramp-shaped start and stop is also acceptable. The rapid shutter cycling time is a matter of convenience it is not necessary for either personnel or patient safety.
4.2 Shutter Controls Control stations are located outside the medical therapy room at the medical control panel, inside the medical therapy room, and in the reactor control room. Each station is equipped with those control functions that are commensurate with safe operation of that station. The controls at the fission converter medical room control panel will consist of open and' close Suttons with appropriate position indicatois for the CCS, water, and I
- mechanical shutters. In addition, there will be a reactor minor scram buttor.. T!c control )
panel itself will be activated by means of a key switch. When the key is removed, these i
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e
Insertion of excess reactivity into the fission converter is not considered to be a credible accident because the fission converter is a highly suberitical system. Analysis has i shown that the kefffor the fission converter is 0.67 or lower, depending on the type of coolant used and the amount of U-235 in the fuel.
The MITR-II SAR calculated the step reactivity limit from a correlation derived from the SPERT experiments. A step reactivity limit of 1.8% AK/K was calculated using that correlation for the MITR to prevent core damage. As part of the MITR relicensing effort, an analysis was recently made using the PARET code. The reactor power, integrated energy generation, fuel, and coolant temperatures were calculated as a function of time. It was concluded that the most limiting scenario is that the reactor is in a low power and low flow rate initial condition. The transient terminated because of the large reactivity feedback from voiding within a few tenths of a second. The insertion of the shim bank in about a .,econd prevents a power oscillation at a later stage of the transient that might otherwise occur because of a positive reactivity feedback from void collapse. The j length of the delay time does not affect the maximum power during this transient. This is l because the power excursion occurs within a few tenths of a second, which is far shorter l than the blade drop time (less th m a second).
)
It was found that the maximum allowable step reactivity insertions are 1.6% AK/K (or $2) for natural convection cooling and 2.4% AK/K (or $3) for forced convection cooling [Ref 6-8]. The actual figure specified for a i;mit for the MITR-II is 1.8% AK/K.
For the MITR-III, limits of 1.2% AK/K for natural convection and 1.8% AK/K for forced convection have been proposed. These figures are conservative. !
As far as the fission converter is concerned, the relevant quantity is the total energy generated. This is because the fission converter power is controlled by the thermal neutron flux coming from the MITR core and that flux is proportional to the MITR power. The fission converter power is about 2.5% of that of the MITR (250 kW/10 MW=0.025).
Therefore, the power deposited in the fission converter would be 2.5% of that in the i MITR. Assuming all the energy is deposited in the fuel plates and neglecting heat transfer I to the coolant, the maximum fission converter fuel temperature would reach 138 C if a step reactivity insertion of 1.6% AK/K (or $2) occurred in the MITR. That insertion is the limiting scenario for the fission converter because it produces the greatest integrated energy.
6.3 Loss of Primary Coolant There are two initiating events that could result in a loss of primary coolant accident for the fission converter - primary pipe breakage and fission converter tank failure. The i fission converter's safety system provides certain protections against this type of accident i In the case of low coolant level, the converter control shutter (CCS) will automatically close. In the case of low primary coolant flow, a converter control shutter closure is i automatically initiated. if the CCS is closed when the coolant level remains above the fuel elements, calculation has shown that the residual hee can be removed initially by coolant evaporation [Ref. 6-4].
A calculation was made to analyze the effect on fuel temperature if the primary coolant were completely lost from the fission converter tank. No credible scenario could be found which would result in rapid and complete coolant loss. Therefore the following should be considered a bounding analysis. The following conservative assumptions were made in this analysis:
6-5 j
6.5 Loss of One of Two Primary Pumps The fission converter primary coolant system is designed to use two primary pumps operating in parallel during normal operation. It is intended that either pump be sufficient to deliver a primary flow rate higher than the scram set point (50 gpm) and that the patient treatment continue if one of the pumps fails during an irradiation. Accordingly, the following analysis was performed to show that this transient would not result in an excessive coolant temperature. The main issue involved in this analysis was the time delay associated with the mixing of the coolant in bulk in the converter tank. The average primary coolant outlet temperature will be higher than the mixing coolant temperature during this transient because of this mixing effect. l The accident analysis is made under the following assumptions.
- 1. The fission converter power is 250 kW.
- 2. The fission converter primary flow rate undergoes a step change from 100 gpm to 50 gpm (scram setpoint). (Note: The design flow rate for one pump operation is i 55 gpm or higher.)
- 3. The initial steady-state primary coolant outlet temperature is 50 C. I 4; Instantaneous mixing is assumed in the fission converter tank region. This was shown to be a conservative assumption [Ref. 6-7].
Figure 6.9 shows the calculated average primary coolant outlet temperature and the mixing area (upper fission converter tank) temperature. The rise in the outlet temperature du.ing the first 10 seconds is the result of the reduced primary flow. The calculation indicates that the average primary coolant outlet temperature starts to decrease after about 30 seconds. This is the result of a decreasing primary coolant inlet temperatum as shown in Figure 6.10. Both the primary coolant temperature and the mixing area coolant temperature approach a new steady-state operating condition in about 300 seconds. The primary coolant outlet temperature reaches a maximum of about 60 C (or 10 C higher than the initial steady-state primary coolant outlet temperature). As shown in Figure 3.8, incipient boiling will not occur until the primary coolant outlet temperature reaches 71 C (at 250 kW).
Therefore, incipient boiling will not occur during this transient.
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i I. '6.8 Mishandling or Malfunction of Fuel The fission convener uses the same fuel as the MITR. The fuel handling tools and .
I procedural considerations that are in use for the MITR will also be used for the fission converter. Also,:he dropping of a fuel element should not result in a radiation release because
- 1. the element would fall thro 2gh water, which would cushion any impact and,
- 2. the fuel is a cermet which would limit the release of fission products should the clad be scratched or otherwise damaged.
It should be noted that all MITR fuel handling tools have a safety lock feature that prevent this type of accident. ;
l 6.9 Exoeriment Malfunction i
4 Experiments may be conducted in the fission converter provided that they comply with existing MITR Technical Specifications that govern samples. These are enumerated in Section 5.5 of ibis SER.- In addition, each type of experiment would be required to have its own safety evaluation This approach is currently followed for all in-core facilities in the MITR. The individual SER would address possiMe malfunctions. These evaluations are subject to review by the Reactor Operations Staff and the MIT Reactor Safeguards Committee.
l 6.10 Natural Disturbances Safety analyses for natural disturbances for the MITR-II apply for the fission j converter. Most of the following is from the M1FR-II SAR.
1 i
6.10.1 Eanhquake A seismic study c,f the Cambridge area is described in the Section 2.5 of the MITR-II SAR. The Cambridge area lies in the Boston Basin which has been relatively free of earthquakes in recorded times. In view of the past seismology records and the conservative design of the fission conerter, it is unlikely that earthquake damage poses any hazard.
Furthermore, reactor shutdown is expected to occur in the event of a significant earthquake and therefore, would also shut down the fission converter.
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CHAN GES TO THE FISSION CONVERTER l TECHNICAL SPECIFICATIONS
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- 2. The fission converter may be operated at power levels up to 20 kW in the absence of forced convection, provided that the inlet pipes are removed so as to allow natural circulation. The measured values of the limiting safety system settings on P, Tmix, and H for fission converter operation with natural circulation shall then be as follows:
Variable Limitine Safety System Setting P 20 kW (max)
Tmix 60 C(max)
H 2.5 m above top of fuel elements (min) !
l Basis !
f The limiting safety system settings (LSSS) are established to allow a sufficient margin between normal operating conditions and the .;afety limits, so that automatic shut down actions will ensure that the fission converter is maintained in a safe condition during normal operation. Onset of nucleate boiling (ONB)is chosen as the criterion for the LSSS derivation. ONB (also called incipient boiling) defines the condition where bubbles Grst start to forrn on the heated surface. Because most of the liquid is still subcooled, the l bubbles do not detach but grow and collapse while attached to the wall. LSSS are chosen so that boiling will not occur anywhere in the fueled region as long as the limits are not l
exceeded.
The ONB is calculated in the Fission Converter SER for the hot channel.
Uncertainties because of departure from nominal design specification, measurement errors, 1
and the use of empirical correlations are taken into account in these calculations. The LSSS were evaluated based on the limiting core operating conditions described in TS# 6.6.2.1.
Fiyure 6.6.1.2-1 shows the result of the fission converter LSSS calculations for a primary coolant flow rate of 45 gpm and a coolant height of 2.1 m for operation with 6-41 1
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4 .-
forced convection. The LSSS temperature calculated for 300 kW is 63 C, and hence a primuy coolant outlet temperature setting of 60 C is conservative.
, For fission converter operation with natural circulation, calculations have shown
]
that the prediction of ONB coincides with that of OSV because of the low flow rate.
Therefore, a 5 C margin is added to the safety limit curve to establish the LSSS. This 5T margin corresponds to about 6 minutes of heat up time in the mixing area with the fission I converter at 20 kW and thus provide adequate response time for corrective actions. The resulting LSSS curve is shown in Figure 6.6.1.2-2. The LSSS for fission converter operation with natural circulation is conservatively determined for a maximum power of 20 kW and a maximum coolant mixing temperature of 60 C with a coolant height of 2.5 m.
450 ,,,, ,,,, ,,,,s ,,,, ,,,, ,,,,
~400 H = 2.1 m N Wp = 45 gpm 350 s' : :
o., . . 1 300 -
250 ---
200 '
45 50 55 60 65 70- 75 Tout ( C)
Figure 6.6.1.2-1 Calculated Results for the Fission Converter LSSS for Operation with Forced Convection. (for either ten or eleven fuel elements) 6-4f
r.
t.
l 40 ,,, ,,,,, , , , , ,,,, ,,,, ,,,, ,,,, ,,,,
35 -
H = 2.5 m --
J 30 4-
[- .
i G
x 25 A
T -
20 -
, 1 15 = 4 .
10 35 40 45 50- 55 60 65 70 75 l l
l Tmix( C) !
I Figure 6.6.1.2-2 Fission Converter LSSS for Operation with Natural Convection (for eleven fuel elements or.ly)
W-O 6-43
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- x. -
l
. 1 4
Table 6.6.2.5-1 Minimum Required Safety Channels for Fission Converter Operation i l
I Channel Automatic Action Setpoint Min. No. l Range Required Operation with Forced Convection Flow Primary Flow Rate Reactor Scram
- and 2 45 gpm i Converter Control Shutter Closure l Power Convener Control Shutter Closure s 300 kW 1 Outlet Temperature Converter Control Shutter Closure s 60 C 1 Coolant Level Reactor Scram
- N/A 1 from the Fission Converter l Medical Control Panel l Operation without Forced Convection Flow Power Reactor Scram ** and 5 20 kW 1 Converter Contrei Shutter Closure Outlet Temperature Converter Control Shutter Closure s 60 C 1 Coolant Level Reactor Scram
- N/A 1 from the Fission Converter Medical Control Panel Not required if fission converter is in either a shutdown or a secured condition.
For natural convection operation only and not required if fission converter is in either a shutdown or a secured condition.
6-54 m i