ML20217G225
| ML20217G225 | |
| Person / Time | |
|---|---|
| Site: | MIT Nuclear Research Reactor |
| Issue date: | 10/03/1997 |
| From: | NUCLEAR REACTOR LABORATORY |
| To: | |
| Shared Package | |
| ML20217G214 | List: |
| References | |
| NUDOCS 9710090262 | |
| Download: ML20217G225 (34) | |
Text
O TECHNICAL SPECIFICATIONS FOR O FISSION CONVERTER FACILITY OCTOBER 3,1997
+
0 0
T/,BLE OF CONTENTS V( 3 Page 6.6 Design and Operation of the Fission Converter Facility.................. ............ 6-34 6.6.1 Safety Limits and Limiting Safety Svstem Settings........ .................. 6-36 6.6.1,1 S afe ty Li mi t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6- 3 6 6.6.1.2 Limiting Safety System Settings (LSSS) ................. ... ..... 6-40 6.6.2 Limiting Conditic,ns for the Fission Converter Operations................... 6-43 l 6.6.2.1- Limiting Operating Conditions for the Fueled Region .......... 6-43 6.6.2.2 Maximum Allowed Rate of Reactivity Addition ................. 6-46
- 6.6.2.3 Closing Time of the Cadmium Curtain or Equivalent........... 6-47 6.6.2.4 Fission Converter Fuel Element Security, Storage, and H a n d l i n g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6- 4 8 6.6.2.5 D2/H2 Concentration and Recombiner Operation................ 6-50 6.6.2.6 Fission Converter Safety System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 52 (3 6.6.2.7 Fission Converter Primary Coolant Quality Requirements..... 6-54 d
6.6.3 Fission Convener Surveillance Requirements................................. 6-56
~ 6.6.4 Fi,ssion Converter Desig n Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . 6-58
)
D v
i
.=
6.6 Design and Operation of the Fission Converter Facility
\d Applicability This specification applies to the operation of the Fission Converter Facility, it does not pertain to the use made of the fission converter beam nor does it apply to the associated medical therapy facility. Use of that facility for the treatment of human patients and/or investigatory studies that involve humans shall be in accordance with the provisions of TS#
6.5 and its associated quality management program.
Oreanization This specification contains four subsections. These are:
6.6.1 Safety Limits and Limiting Safety System Settings 6.6,2 Limiting Conditions for Fission Converter Operation 6.6.3 Fission Converter Surveillance Requirements A
- 6.6.4 Fission Converter Design Features
'v c
6-34
Definitions
/ 1, Fissinn Converter Shutdown That condition where the cadmium curtain or its equivalent is fully it.serted or where the reactor is in a shutdown condition. The fission converter is considered operating whenever this condition is not met,
- 2. Fission Converter Secured The overall condition where there is no fuel in the nssion converter or all of the following conditions are satisfied:
(a) The nssion converter is shut down, s
(b) The fission converter medical control panel key switch is in the off position and key is in proper custody, and (c) There is no work in progress within the converter tank involving fuel.
O 6 35
6.6.1 Safety Limits and Limiting Safety System Settings es.
6.6.1.1 Safety Limits Aonticability This specification applies to the interrelated variables associated with fission converter thermal and hydraulic performance. These variables are the fission converter neutronic power (P), the steady-state average primary coolant outlet temperature (Tout) if under forced convection, the fission converter tank coolant mixing temperature (Tmix) if under natural circulation, the fission converter primary coolant flow rate (W p), and the fission converter primary coolant height in the main tank (H).
Obiective l To establish limits within which the integrity of the fuel clad is maintained.
Specification 1,
For forced convection, the point determined by the true values of P, Wp, and Tout sha" not be above the line given in Figure 6.6.1.1-1 corresponding to the coolant height, H.-
- 2. For natural convection, the coolant height shall be at 2.4 m or higher and the point determined by the true values of P and Tmixs hall not be above the line given in Figure 6.6.1.1-2.
O V
6-36
i O .
9 .,,,... ,,,,.. . , , , , , , ,
j .
)-
j .
i .
8 ---
H=2.'6 m r 4 .
~
~
H=2.1 m ; .
7 4
- t, .
P (kW) H=1.6 m ;
Wp(gpm) - ;> l 6 - - - - - - -
+ .
l p -
U 5
- - - --- -?-
, i :
t- - =
[
j .
i .
- ? .
i -
t t a a i e I e a ie a e a ! e e o e i e e a ,
60 65- 70 75 80 85 Tout ( C)
Figure 6.6.1.1-1 Fission Converter Safety Limits for Forced Convection.
1 O 6-37 m _ . .
I 40 ,,, ,,,, ,,,,,,,,, ,,,, ,,,, ,,,, ,,,,
=: .
. i .
. j .
35 -
- 4- f.~ H = 2.4 ---
30 --
-- r -
+----r----- ------
i i .
l .
y' .
a 25 = +
-r
~ . 1 I-
.I .
- c. -
- 2. .
3 I .
20 1; -
j- + '
-y- .t -
\ .
-15 -
+
r l )
i .
- 10 m ''''' ' ' ' '
40 45 50 55 60 65 70 75 80 Tmix( C)
Figure 6.6.1.12 Fission Converter Safety Limits for Natural Convection.
6-38
Basis In the MITR SAR it is noted that critical heat flux is a conservative limit beyond which fuel damage may occur from overheating. In addition, the onset of multichannel flow instability (OFI) can lower tiie burnout heat Dux. However, OFI is a complicated phenomenon and the effects of heat flux spatial distributions are not taken into account in the correlations developed for OFl. Onset of significant voiding (OSV), on the other hand, can be more accurately predicted for various heat flux spatial distributions. Also, it has been observed experimentally that OSV occurs before OFl. Therefore, OSV is conservatively assumed as the criterion for the safety limits of tl c fission converter.
OSV was calculated in the Fission Converter Safety Evaluation Report (SER) for the hot channel based on ten or eleven fuel elements. Uncertainties because of departure from nominal design specifications, measurement errors, and use of empirical correlations l are taken into account in these calculations. The safety limits were evaluated based on the limiting core operating conditions described in TS# 6.6.2.1. Figure 6.6.1,1-1 shows the q
Q calculated fission converter safety limits for forced convection for three coolant heights:
2.6 m,2.1 m, and 1.6 m above the top of the fueled agion.
The purpose of allowing fission converter operation at low power in the absence of forced convection is to facilitate activities such as aux measurements in the fueled region.
Natural circulation is achieved by removing the inlet pipes, which are used for forced convection, from the downcomers. Calculations show that the natural circulation is sufficien' to dissipate the energy that is generated provided that the limit on the fission converter tank coolant mixing temperature is not exceeded. OSV for natural circulation was calculated for a coolant height of 2.4 m. This coolant height corresponds to the top of the downcomers. The result for ten or eleven elements is shown in Figure 6.6.1.1-2.
b o 6-39
6.6.1.2 Limiting Safety System Settings (LSSS)
( ,-
f Apolicability This specification applies to the setpoints for the safety channels monitoring the f
fission converter neutronic power (P), the steady-state average primary coolant outlet temperature (Tout) if under forced convection, the fission converter tank coolant mixing temperature (Tmix) if under ratural circulation, the fission converter primary coolant flow rate (Wp), and the fission converter primary coolant height in the main tank (H).
Obiective To assure that automatic protective actions will prevent the onset of nucleate boihng in the fission converter fueled region and will thus prevent operating conditions from exceeding the safety limit.
- Snecification x-
- 1. The measured values of the limiting safety system settings on P, W p, Toui, and H for fission converte. operation with forced convection shall be as follows:
Variable Limitine Snfety System Settine P 300 kW (max)
Wp 45 gpm (min)
Tout 60 C(max)
H 2.1 m above top of fuel (min)
- 2. The fission converter may be operated at power levels up to 25 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 g
a 6-40 I
U
P, Tmix, and 11 for fission converter operation with natural circulation shall then be (m)
LJ as follows:
Variable Limitine Safety System Setting P 25 kW (max)
Tmix 60 'C (max)
H 2.4 m above top of fuel (min)
Basis The limiting safety system settings (LSSS) are established to allow a sufficient margin between normal operating conditions and the safety 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 l
j derivation. LSSS are chosen so that boiling will not occur anywhere in the fueled region as
[]
v long as the limits are not exceeded.
The ONB is calculated in the Fission Converter SER for the hot channel based on ten or eleven fuel elements. Uncertainties because of departure from nominal design specificatior., measurernent errors and 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.
Figure 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 forced convection. The LSSS temperature calculated for 300 kW is 63 C, and hence a primary 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 low surface heat flux.
So the LSSS for the fission converter operation with natural circulation is conservatively
?
w]
r 6-41
determined for a maximum power of 25 kW and a maximum coolant mixing temperature of-60 C with a coolant height of 2.4 m. .
450 ,,,, , , , , ,,,, ,,,, ,,,, ,,,,
400 = . . H = 2.1 m .-...-
Wp = 45 gpm -
350 = 4- - - - - - =
.~ . .
3 . .
-6 .
a.- . .
300 .
i- .
250 -
-+ --
-r i .
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,
\
6-42
6.6.2 Limiting Conditions for the Fission Converter Operations
(~~\
V 6.6.2.1 Limiting Operating Conditions for the Fueled Regi9n Applicability This specification applies to the fission converter core operating conditions. The variables used to define the core operating conditions are:
Fp the fraction of the total power deposited in the fueled region (both fuel and coolant),
Feil the ratio of the maximum power deposited in the hottest fuel plate to the average power per fuel plate, Fr the ratio of the primary coolant flow that goes through the fueled region to the total primarf coolant flow, and dr the ratio of the minimum flow to the average flow in the coolant channels.
O Objective To assure that the operating parameters are maintained within the bounds that are used to establish the safety limits and the limiting safety system settings of the fission converter.
Specification
- 1. Fp x Encs 1.53
- 2. Fr x dr 2 0.80
- 3. After each change in loading of the fueled region which might increase the hot channel factor, an evaluation will be made to ensure that item (1) above is satisfied.
O O
6-43 I
A record of these evaluations shall be approved by two licensed SROs, one of whom shall have an advanced degree in engineering or a related field.
- wf]/ -
- 4. All positions in the fueled region are filled with either a fuel element or another approved unit. For other than ten or eleven fuel elements in the fueled region, the above specifications (TS# 6.6.2,i (1) and (2)), the safety limits, and the LSSS shall be re-evaluated.
- 5. The maximum fuel bumup shall be limited in accordance with TS# 3.11(2e)
- 6. The maximum allowed value of kerr for the fueled region shall not exceed 0.90.
- 7. Fuel elements contained in the fueled region of the fission converter shall be oriented so the plates are " edge on" towards the MITR core.
- 8. The fission converter tank lid shall be in place for operation greater than 25 kW.
l Basis The fission power deposition factor (Fp), the hot channel factor (FH c), the fueled i region coolant flow distribution factor (Fr), and the channel flow disparity factor (d f) are all dependent on the fission converter fueled region design. The specifications (TS# -
6.6.2.l(1) and(2)) that describe the limits an these factors are conservatively determined
-for the fission converter design and provide reasonable margin for deviations. These factors form the basis for the thermal hydraulic limits calculations and they should be verified during initial startup of the fission converter.
Safety limits and limiting safety system settings of the fission converter described in TS# 6.6.1 are derived based on ten or eleven fuel elements in the fueled region. For other than ten or eleven fuel elements, these limits shall be re evaluated.
The maximum fuel burnup density is chosen in accordance with TS# 3.11(2e).
This limit was developed based on the MITR fuel design.
The effective multiplication factor (kerr) for the fission converter was calculated in the SER for different combinations of coolant and fuel element U-235 content using the O
v 6-44
hSnte Carlo N Particle (MCNP) code. The kerr values calculated for a D 0 cooled system
,, are 0.268 for partially spent MITR-Il fuel and 0.344 for fresh MITR il fuel For an 110 2 cooled system, the kerr calculated values are 0.514 and 0.618 for partially spent and fresh MITR-il fuel, respectively. Because the kerr predicted is much smaller than unity, a criticality accident is not credible. The criterion of a kerr less than 0.90 was chosen because it is in accordance with TS# 3.10 (4) for fuel storage locations.
Calculations show that the power peaking in the hot channel would be unacceptable if the elements were to be rotated so that fuel plates were facing the MITR, Therefore, administrative procedures will be used to ensure that fuel elements are loaded with an
" edge-on" orientation.
Operation of the fission converter without the top shield lid in place is allowed for l power levels up to 25 kW. Calculations in the fission converter SER have shown that the j estimated dose rate at that power level is 560 mRih at the coolant surface with a coolant i
i height of 2.4 m. This dose rate is not in excess of those occasionally encountered during l / certain mainte'1ance operations, and it has been demonstrated that administrative actions can provide adequate controls under such conditions. Adequate controls will be instituted during such experiments to prevent excessive personnel exposure.
O v
6-45
6.6.2.2 Maximum Allowed Rate of Reactivity Addition n 1 Q
Apolicability This specification applies to the rate with which the cadmium curtain or its equivalent is opened.
Obiective To ensure that the integrity of the MITR fuel is maintained during operation of the fission converter.
Snecification j Opening of the cadmium curtain or its equivalent shall not result in a reactor period l
shorter than 50 seconds in the absence of action by the reactor console operator.
, ./
(Oj Basis MITR Technical Specifications provide several approaches for limiting the reactivity associated wittum experimental facility. MITR Technical Specification 6.1 imposes limits depending on whether the experiment is classified as moveable, non-secured, or secured.
MITR Technical Specification 6.4 imposes a limit on the allowed period for experiments related to reactor control research. The latter approach provides more flexibility because it permits any combination of reactivity and rate of change of reactivity provided that a certain minimum period is not exceeded. Accordingly, this approach is used for the fission converter. Reactor controls can be easily used to negate any change in reactor power that results from the initiation of fission converter operation, provided that the reactor period is 50 seconds or longer.
(v) 6-46 d
6.6.2.3 Closing' *inle_of the Cadmium Cunain or Eauivalent O Applicability l This specification applies to the operation of the fission convener cadmium curtain or its equivalent.
Dissdra To ensure that the integrity of the fission converter fuel is maintained during a loss of flow transient with no reactor sctam.
Soccincation The fission convener shall not be operated unless the maximum closing time of the cadmium cunain or its er;uivalent is less than 60 seconds.
In the event of loss of fission ec,verter forced flow, the primary means of protection is a reactor scram. Should there be a failure to scram, closure of the cadmium cunain or its equivalent within 60 seconds would preclude overheating of the fission convener fuel.
O 6-47 t
w -
- .. . _ _ _ _ _ . . _ . _ _ _ _ _ . _ - _ _ _ _ __ ._ _.m _ _ . _ _ _ ._.
6.6.2.4 Fission Converter Fuel Element Security. Storage. ani l llandling
(
v Applicability This specification applies to the security, storage, and handling of the fission converter fuel elements.
Oblective To assurt .at the fueled elements will be properly stored and handled in a manner to protect the safety of reactor personnel.
Soccification
- 1. All fuel elements used in the fission converter fueled region shall be maintained self ptotecting Calculations or measurements documenting self protection shall be approved by two licensed SRos, one of whom shall have an advanced degree in engineering or a related field.
- 2. Fisslor converter fuel elements shall be stored in accordance with the provisions of TS# 3.10(1) and either (2) or (3) as applicable.
- 3. Prior to transferring an irradiated element from the fission conurter tank to the iransfer cask, the operating history for the element shall not exceed one of the following thite requirements:
(a)- Continuous operation at or below 50 kW for the four days prior to refueling.
(b) A maximum operating time of 4.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> per day at or below 250 kW during the four days prior to refueling.
(c) A maximum burnup of 436 kWh per fuel element during the four days prior to refueling.
6-48
lhish l
TS# 3.10(4) specifies that prior to transferring an irradiated element, that fuel l clement shall not have been operated in the reactor core at r. power level above 100 kW for at least four days. This requirement can not be translated directly to the fission converter because of the diffetent numbers of elements in the reactor core and in the fission l converter. Alternatively, an equivalent power history is used for the nssion convener.
l A study was conducted in the SER to calculate the fuel plate temperature during fuel element removal, it was assumed that the fission converter was operated continuously at its maximum operating power of 250 kW until four days prior to removal of the fuel I element. During those four days, operation was as ds: scribed in the specincation. It was also assumed that all heat transfer was by radiation alone during the fuel transfer. The maximum clad temperature was calculated to be 313*C which is well tclow the Al 6061 softening temperature of 450 'C.
O 6-49 i
l
6.6.2.5 D2lll2 concentration and Recombiner Operation
' APEliG1hililX This specification applies to the D 2of 112 ga; e.,acentration in the helium cover gas blanket over the fission converter tank, and to Ibc operation of the recombiner system. In the event that the fission converter is operated without !! top shield lid, this specification is not applicable.
l Objective To prevent a flanunable concentration of either D2 or 112 gas in the helium blanket.
Speelfication
- 1. The D 2concentration in the helium blanket shall not exceed 6 volume percent if D 20 is used a the primary coolant in s 'e fission converter.
3 (V 2. The 112 concentration in the helium blanket shall not exceed 6 volume percent if 1120 is used as the primary coolant in the Ossion convener.
- 3. The recombiner shall be operated continuously for a minimum of S hours per tnonth, Such operation shall be in accordance with manufacturer's directions.
- 4. Operation of the recombiner shall be in accordance with manufacturer's directions.
In the event that the recombiner is not operable, fission converter operation may be continued provided that D2/li 2samples are taken weekly, and that the D2 /Il2 concentration in the helium blanket does not exceed 2 volume percent, llah Recombination of the disassociated D2 /II2 and O2 is accomplished by continuously circulating the helium from above the fission converter tank through a recombiner.
(v3 6 50 i
m "
t-3 I-i
! Operation of the recombiner (such as reaction chamber temperature and now rate) shall i
follow the manufacturer's instructions.
i The concentration limit of D /li in 2 helium blanket is obtained from TS# 3.3(1), in which the concentration is conservatively determined from extrapolation of Hammability
, limits.
{.
I i
1 r
9 <
I 0 6 51
. _ = _ _ . _ _ _ -.
6.6.2.6 Fission Convener Safety System O Applicability This specification applies to the operability of the fission converter safety channels.
Objective -
To assure that adequate automatic protective actions are provided by the safety ,
channels during operation of the fission converter.
Snecification
- 1. The fission converter shall not be operated unless the safety channels listed in Table 6.6.2.61 are operable.
- 2. Emergency power with the capacity to operate the equipment listed in Table 6.6.2.6-2 of this specification shall be available whenever the fission converter is
. operating and shall be capable of operation for at least one hour following a loss of normal power to the facility.
Ilails The parameters listed in Table 6.6.2.61 are monitored by the fission converter safety system. This system automatically initiates cadmium curtain closure and/or a reacter scram to assure that the LSSS and safety limits are not exceeded.
The use of emergency power is not essential for the fission converter because loss of power automatically scrams the reactor and thus the fission converter. Both the mechanical and water shutters close by gravity upon power failure. Nevertheless, the information supplied to the reactor operator and fission converter user that the fission converter is shut down will assure personnel radiation safety. The choice of a minimum of one hour is based on TS# 3.7(3).
O MJ 6 52 l
l
l Table 6.6.2.6-1 Minimum Required Safety Channels for Fission Converter Opervion
,Q U Channel Automatic Action Setpoint Min. No.
Range Required Operation with Forced Convection Flow Primary Flow Rate Reactor Scram
- and 2 45 gpm I Cadmium Curtain Closure Power Cadmium Curtain Closure <; 300 kW l Outlet Temperature Cadmium Cartain Closure s 60 'C 1 Coolant Level Reactor Scram
- and 2 2.1 m 1 Cadmium Curtain Closure i hianual Reactor Minor Scram Reactor Scram' N/A 1 from the Fission Convener Medical Control Panel Operation without Forced Convection Flow Power Cadmium Curtain Closure 5 25 kW l Outlet Temperature Cadmium Curtain Closure s60'C 1
(~'g 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.
Table 6.6.2.6-2 Minimum Equipment to be Supplied by Emergency Powei
- 1. Fission converter medical therapy room radiation monitor.
- 2. Intercom between the fission converter medical therapy room and its associated medical control panel area.
- 3. Intercom between the fission converter medical control panel area and the reactor control room.
5 Emergency lighting of the fission converter medical therapy room and its associated medical control panel area.
- 5. Safety channels listed in Table 6.6.2.61.
O
\)
6-53
6.6.2.7 Fission convener Primary coolant Ouality Requiremtals O App 1'cability t
This specification applies to the pil, conductivity, and activity of the fission converter primary coolant.
Obiective To control corrosion of the fission converter fuel and primary coolant loop structure, and activation of impurities and leakage of fission products in the fission converter primary coolant.
Soccification
- 1. The pli of the fission convener primary coolant shall be kept between 5.5 and 7.5.
Excursions beyond the specified range are permitted provided that the time wei,,hted monthly average is within the specified range.
2, The conductivity of the fission converter primary coolant shall be kept less than 5 pmho/cm at 20'C. Excursions in excess of this value are permitted provided that ,
the time weighted monthly average is less than 5 pmho/cm,
- 3. Any gross pq sample activity that exceeds the average of these monthly values by a factor of three or more shall be investigated to determine the cause.
Basis The purpose of pli monitoring is to ensure corrosion on the fission converter fuel and the primary coolant loop stmeture is maintained within an acceptable limit. The fission converter f tel cladding and the fission converter tank are made of aluminum alloy. A 6-54
portion of the primary coolant loop is constructed of stainless steel. Lower pil will reduce aluminum alloy corrosion and oxide film formation on the fuel surface and higher pil is favored to control sta 'ess steel corrosion. Thus a pli range between 5.5 and 7.5 is-selected for the fission converter primary coolant.
Electrical unductivity is also monitored to control purity of the fission converter primary coolant. A conductivity limit of 5 pmho/cm has been traditionally adopted by l research reactors.
The criterion that gross p.y activity three times in excess of the average value be
' investigated is in accordance with industry practice for the detection of incipient fuel failure.
In order for this criterion to be applied with a consistent basis, only samples that have similar power histories should be compared.
O l
O 6-55
6.6.3 Fission Converter Surveillance ReavitemcDu em ,
Applicability This specification applies to the surveillance of safety systems whose opration is imponant to fission converter safety.
Objective To assure the reliability of the instrumentation imponant for safe operation of the fission convener.
Sneci6 cation
- 1. The following instruments or channels for the fission converter safety system will be tested at least monthly and each time before startup of the reactor if the reactc.r has been shut down more than 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> and if the fission convener facility will be
[v used within that reactor operating period. The monthly requirement may be omitted if the fission convener facility will not be used during that month.
Instrument. Channel. or Interlock Functionni Test Primary coolant flow Automatic cadmium cunain closure and reactor scram Neutron flux level Automatic cadmium cunain closum Primary coolant outlet temperature Automatic cadmium cunain closure Fission convener tank coolant level Automatic cadmium cunain closure and reactor scram V
6-56
- 2. The following instmments used in the fission converter facility shall be calibrated and trip points verified when initially installed, any time the instrument has been repaired, and at least annually:
- a. Neutron Dux level channel,
- b. Primary coolant flow channel,
- c. Primary coolant outlet temperature channel, and
- d. Fission converter tank coolant level channel,
- 3. The neutron flux level channel and a fission converter primary system heat balance shall be checked against each other at least annually and when design changes in the 4 reactor and/or the fission converter are made that may affect the existing calibration result.
- 4. The pit, chloride content, and gross y activity of the fission converter primary coolant shall be determined at least monthly. The conductivity of the fission converter primary coolant shall be determined either by a continuous on line instrum,,ent or a monthly sample. The tritium content and isotopic purity of the coolant shall be determined quarterly if D 20 is used as the fission convener primary coolant.
Ilaiis The specifications for functional tests, calibrations, and primary coolant sampling adhere to current MITR practice.
The annual frequency for performance of the calorimetric was chosen because the fission convener's power is a function of the MITR's power and the burnup of the fission converter fuel. The latter will occur very slowly. Hence, the annual performance of a ,
calorimetric is sufficient to detect any change in Ossion convener power production, n
v 6-57
6.6.4 fission Converter DesigrLEcatures O MPllGDililX This specification applies to the design of the fission converter tank, fueled region,-
and primary coolant system.
Obiectivy To assure compatibility of the fission converter design features with the present i safety evaluation.
Snecification
- l. The fission converter primary coolant system can utilize either H2 O or D2O coolant.
- 2. All materials that are in contact with primary coolant, including those of the converter tank, shall be aluminum alloys, stainless steel, or other materials that are chemically compatible with 110 2 and D 20 coolant, except for small non-corrosive components such as gaskets, filters, and valve diaphragns
- 3. The fueled region of the fission converter may censist of up to eleven fuel elements of a type described in TS# 5.2(1).
- 4. The fueled region of the fission converter may contain sample assemblies provided that they conform to the requirements of TS# 6.6.2.l(4) and TS# 5.2(2).
- 5. The pumps and other components of the fission converter's primary cooling system shall be located physically above the fission converter tank in order to prevent siphoning.
pd 6-58
. .. .)
}
i-1 J) asis l
The two materials specifications are in keeping with those imposed on the design of j the MITR. The specifications on fuel type and samp'e assemblies impose the same criteria i as used for the MITR.
l I
i-I t
t l'
I l
f l
l l ;
I i
i 3
i 1
i I !
l
- 1. !
- 9 6-59 l
1 l .
k 3
4 1
i
!O i
j r
4 l
4 CHANGES TO CURRENT MITR i
} TECHNICAL SPECIFICATIONS .
1
!O 6
60 OCTOBER 3,1997
)
i 1;
!O i
- l. DEFINITIONS O
1.1 Reactor Senged The overall condition where there is no l'uel in the reactor core or all of the following conditions are satified:
- 1. the reactor is shut down,
- 2. console key switch is of,"and key is in proper custody.
- 3. no work in progress within the main core tank and/or the fission converter tank involving fuel or experiments, or maintenance of the core structure, installed control blades, or installed control blade drives when not visibly l decoupled from the control blade.
1.2 Reactor Shutdown That condition where all control blades are fully inserted or reactivity condition equivalent to one where all control blades are fully inserted. The reactor is considered to be
/"
(w operated whenever this condition is not met, I 1.3 Containment Intecrity Integrity of the containment building is said to be maintained when all isolation system equipment is operable or secured in an isolating position, 1.4 The True Value The true value of a parameter is its exact value at any instant.
1.5 The Measured Value The measured value of a parameter is the value of the parameter as it appears on the output of a measuring channel, p
O l-1
... _J
- a. a radiation monitor continually sampling the effluent air stream, which indicates in the control room, shall be operating and capable of automatically closing the building vents. The time for the radiation monitor trip, including sample transit and ventilation damper closing times, shall be less than the time for effluent air to flow from the sampling point to the damper,
- b. a radiation monitor in the exhaust stack shall be operating.
- c. the tritium concentration in the stack effluent shall be measured so as to provide a monthly average value.
- 3. Whenever the reactor is operadng with secondary cooling water circulating between the reactor building and the cooling towers, a seenndary water radiation monitor, which indicates in the control room, shall be operating.
- 4. Whenever secondary cooling water is flowing through the D20 heat exchang~-
and/or the fission converter heat exchanger (if D2O is used as coolant) to the cooling towers the following shall be provided:
- a. the secondary water shall be sampled daily for tritium content.
b, the level of the D20 dump tank shall be monitored, either by a low level ularm in the control room, or by hourly readings of the dump tank sight glass,
- c. the level of the fission converter tank shall be monitored by a low level alarm in the control room or by hourly reading of a local guage.
- 5. At least one area radiation monitor, capable of warning personnel on the reactor floor of high radiation levels, shal! be operating when the reactor floor is occupied, if one of the five normal area monitors is inoperative, portable instruments will be used to survey work in that area.
i n/
3-27
= _._ _
- a. in the reactor core provided the teactivity is below the shutdown margin given by Specification 3.91,
- b. in the cadmium lined fue. itorage ring attached to the now shroud,
- c. in the dry storage holes on the reactor top,
- d. In the spent fuel storage tank in the basement of the reactor building,
- c. in the fuel element transfer flask or other proper shield within the controlled area,
- f. In the fission converter tank.
l
- 4. Handling of fuel elements: Only one fuel element at a time shall be moved in or out of the reactor core. Not more than four of the MITR fuel elements or the equivalent of two fuel elements including loose plates (maximum of 15 loose fuel plates) shall be outside of the storage areas as designated in items 2 and 3a, b, c, d except during the processes of receiving or shipping p fuel from the site in approved containers, in all cases of fuel element V
storage outside of the reactor core, the value of kerr must be kept less than 0.90. Records of fuel element transfers shall be maintair.ed. Prior to transferring an irradiated element from the reactor vessel to the transfer Dask, the element shall not have been operated in the core at a power level above 100 kW for at least four days.
- 5. Removal of control blades: A control blade may be removed from the core only if the minimum shutdown margin relative to the cold, Xe-free critical condition with the most reactive operable blade and the regulating rod fully
_ withdrawn is 1% Ak/k after the control blade has been removed.
n v
3 37 l
lt has been calculated that fue! < lements when stored in the locations specified in 2b, 2c,2d,3b,3c,3d, and 3f will have a calculated effective rnultiplication (kerr) factor ofless than 0.9 under optimum conditions of water moderation.
These specifications are also conservative for criticality safe handling of MITR 1 fuel alone or in combination with MITR Il fuel.
The chief additional problems with spent fuel are those of shielding personnel from the emitted fission product gamma rays and preventing mciting from afterheat. The shielding requirement is met by utilizing a shielded transfer flask for movements and temporary storage and more permanent shielding as indicated in 3a, b, c, d, and f. The requirement to prevent melting is met by specifying that four days elapse between use of l the fuel element in a core operating above 100 kW and removal of the element from the reactor pool. This decay time was determined from experience with the MITR 1 combined with a conservative assumption of doubling the power density for the MITR II.
The specif~: cation on removal of control element provides that the stuck rod criteria will always be met, even when one blade is removed for repair. Thus, the reactor still would not go cfitical on the removal of a second control element.
v 3 39
_=: -
V
l (ii) if the operator is unable to turn the primary beam of radiation off with controls outside the medical therapy facility, or if any other abnormal I condition occurs. A directive chall be included with these instructions to notify the reactor console operator in the event of any abnonnality.
(c) In the event that a shutter affects reactivity (e.g., the D2 0 shutter for the medical room below the reactor and the cadmium shutter for the fission converter beam), personnel who are not lkensed on the MIT Research Reactor but who have been trained under this provision may operate that shutter provided that verbal permission is requested and received from the reactor console operator immediately prior to such action. Emergency closures are an exception and may be made without first requesting permission.
Records of the training provided under subparagraph (a) above shall be retained in accordance with the MIT Research Reactor's training program or at least for three years. A list of personnel so qualified shall be maintained in the reactor control room.
- 17. Events defined as ' recordable' under definition 8 of this specification shall be V recorc'ed and the record maintained for five years. Events defined as
'misadministrations' under definition 9 of tais specification shall be reported to the U.S. Nuclear Regulatory Commission (24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> verbal,15 day written report). The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> verbal reports will be made to the Regional Administrator, Region 1, or his designate. The 15 day written reports will be sent to the NRC Document Control Desk with a copy to the Regional Administrator, Region I, or his designate.
18, The requirements of the Quality Management Prcgram (QMP) for the Generation of Medical Therapy Facility Beam for Human Therapy at the Massachusetts Institute of Technology Research Reactor shall be observed for any human therapy. (Nnts: The presence of this commitment to observe the QMP in these specifications does not preclude modifying the QMP as provided in that document. Any such modifications are not considered to be a change to the MITR Technical Specifications.)
O 6 27'