ML19329E033
| ML19329E033 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 10/31/1967 |
| From: | SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| References | |
| NUDOCS 8004090670 | |
| Download: ML19329E033 (12) | |
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APPENDIX 11 i
l IIA ANSWERS TO QUESTIONS l
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Amendment 3 All-1
Docket 50-312 m
Amendment No. 1 February 2, 1968 QUESTION Provide a Radiation Monitoring System schematic similar to the 11A.1 format of Figure 7.1-2 which indicates location, equipment type, power sources, and interlock functions. The schematic should show the relationship of the area, waste and gas disposal, ventil-ation, and site monitoring systems. The schematic should be accompanied by adequate description.
ANSWER.
The Radiation Monitoring System will consist of the Process Refer to Radiation Monitoring System and the area Radiation Monitoring g
11.2.2 System. Control room area monitors will be located close to l3 the control console. The system functions are the early detection of an abnormal rise in radiation within the reactor complex and at selected locations on the reactor site perimeter, an audible alarm of the location of the abnormal radiation and the display of the level of the radiation as a visual or printed record.
The Process Radiation Monitoring System function is to detect early indication of plant malfunction and the Area Radiation Monitoring System function is to warn personnel of excessive gamma radiation within selected working areas. Except for the waste gas disposal interlock, the signals from the monitoring system are not used for the automatic control of the equipment.
Continuity of operation of the monitoring equipment is assured A
by taking power for the equipment from the Essential Power System.
Schematics of the Area Monitoring and Process Systems are shown on Figures llA.1-1 and llA.1-2.
A-U 0102 Amendment'3 11^-1
QUESTIO::
What actions are initiated upon receipt of a high radiation 11A.2 alarm.
A!!SWER Upon receipt of a high radiation alert alarm the following Refer to action will be taken:
11.2.2 a.
The channel that is alarming will be checked to determine that the alarm is being caused by radiation and not due to equipment malfunction.
b.
For process system monitors, a high radiation alarm will alert the operator and the leaking heat exchanger will be isolated.
c.
For reactor coolant letdown flow, a high radiation alarm will alert the operator to sample the reactor coolant to 4
assess the proper action to be taken.
It is estimated that analysis of the sample will require approximately one hour.
3 d.
For plant vent gaseous discharge alarm an interlock will automatically stop the discharge from the waste gas system.
c.
For area gamma alarms, the area will be monitored with portable instruments to determine the mrem /hr reading.
If a high level is found, the area will be cordoned off and i
properly posted as to dose rate and the necessity of film badges, etc.
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11A-2 Amendment 4
p Cs RB PERSONNEL ACCESS HATCH i
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l l l l RB INCORE INST AREA i
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RB INCORE INST AREA i
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i RB FUEL HANDLING BRIDGE q
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CONTROL ROOM i
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l l l CONTROL ROOM i
FB FUEL HANDLING BRIDGE i
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RADIO-CHEM LAB i
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PRIMARY LOOP i
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/'l l l SITE PERIMETER (4)
RB VENT. FILTERS i
J LEGEND VISUAL ALARM l l l l SCINTILLATION SENSOR FIGURE 11A.1-1
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METER READOUT AUDIBLE ALARM
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G-M SENSOR RECORDERS y y y L. J-
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e SPENT FUEL COOLERS i
SAMPLE COOLERS (2) q i
PRT COOLINO COILS 4
DECAY HE AT COOLERS (2) 4 2
LETDOWN COOLE RS (2) t i
GAS DECAY T ANK DISCH ARGE 4
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/) l l l LETDOWN FLO e
l l l PLANT VENT l
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l l l CONDENSER AIR EJECTOR i
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1 COMPONENT COOLERS (2) 2 NUCLEAR SERVICE COOLERS (2)
J LEGEND VISUAL ALARM ll l l SCINTILLATION SENSOR FIGURE 11A.1-2
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METER RE ADOUT AUDIBLE ALARM r
i G-M SENSOR RECORDERS
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SACRAMENTO MUNICIPAL UTILITY DISTRICT Amendment 3 01.C5
i SEAL RETURN COOLERS (2)
SPENT FUEL COOLERS 4
i 4
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SAMPLE COOLERS (2) y PRT COOLING COILS a
4
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DECAY HEAT COOLERS (2) i q
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LETDOWN COOLERS (2) 4
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i G AS DECAY TANK DISCH ARGE f
LETDOWN FLOW i
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'l l l PLANT VENT 4
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,l l l CONDENSER AIR EJECTOR COMPONENT COOLERS (2) t i
l NUCLEAR SERVICE COOLERS (2)
_J LEGEND FIGURE ]1A.1-2 vlSUAL ALARM ll l l SCINTILLATION SENSOR PROCESS MONITORING SYSTDI
['N k, J METER READOUT
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AUDIBLE ALARM SMUD - -
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i G-M SENSOR RECORDERS 010 SACRAMENTO MUNICIPAL UTILITY DISTRICT Amendment 2
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QUESTION FISSION PRODUCT RELEASE FROM FUEL llA.3 Provide the details of the method of calculating the primary coolant activity levels for the one percent failed fuel case, includi?g purification cycling of primary system, fission product release assumptions from the failed fuel, effects of burnup and fuel temperature on. fission product release from fuel, etc.
Provide all formulae, assumptions, and justifications for same.
Justify the cleanup system reduction factors stated in the PSAR.
ANSWER Activity Levels Refer to 11.1.1 Activity levels in the reactor coolant system resulting from fission product leakage through clad defects are determined with the use of escape rate coefficients. These coefficients repre-sent the fraction of the activity in the fuel that is released, per unit time, to the coolant. Values of these coefficients, as derived from experimental data, are reported in the literature.1-5 These experiments, involving purposely defected fuel elements in pressurized water loops, have been performed for a variety of O
fuel conditions. For a given isotope, the results yield a wide range, of values for the escape rate coefficient even under similar operating conditions. For the calculation of coolant activity levels, values of the escape rate coefficients were determined from these data.
In regard to fuel temperature and burnup, no assumptions were made as to the location of clad defects within the core. The coefficients were conservatively chosen from the available data in an effort to account for the worst fuel condi-tions. The values are shown in Table 11.1-2 of the PSAR.
Calculations of the coolant activity were performed with BURP,6 a Babcock & Wilcox Company digital computer code. This; code solves the differential equations for a five-member radioactive chain for buildup and decay in the fuel, release to the coolant, removal from the coolant by purification or leakage, and collection in a holdup system.
The basic equation ~for the buildup of a radioactive nuclide, N,
f in the fuel is dNf F A'Nj -go - ANg - GNf RY +
=
dt 0107 Amendment 1
'llA-3
Nr concentration of a radioactive nuclide
=
R fission rate, fissions per sec
=
Y independent fission yield of Ng
=
A'Nj activity of precursor in fuel, dis /sec
=
F fraction of precursor which decays to Ng
=
neutron capture rate in Nf, sec-1 00
=
A decay constant of Nf, sec-1
=
escape rate coefficient of Nf, sec-1 a =
The equation for a radioactive nuclide in the coolant, N is e,
given by dNC aNg +
FA'N' - AN - SN
-TcN
=
c c
dt where A'NE activity of precursor in coolant, dis /sec
=
removal of N by purification, sec-1 J
=
e
-1 Y
removal of N by leakage of plate-out, sec
=
c O
In the purification or holdup system the activity of a nuclide, N, is give-by p
l dN D SN
+
FA'N' - AN - aN
=
c dt p
p p
where A'N '
activity of precursor in purification or
=
P holdup system, dis /see G
removal of N from purification or holdup sys-
=
p tem, sec-1 Using the above equations, activities can be computed for more than 200 radioactive fission products with as many as 100 con-secutive reactor operating and shutdown periods. The activity of each ruclide in the fuel, coolant, and holdup or purification systems is computed at each time step, m n ^i 9,i m
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N In the coolant activity calculations, the assumptions regarding operating times, purification flow, and activity removal are given on page 11.1-1 of the PSAR. Activity concentrations in the coolant are shown in Table 11.1-3 of the PSAR.
ANSWER Cleanup System Reduction Factors As stated in Section 11.1.1.3 (page 11.1-1) the activity concen-tration in the coolant, shown in Table 11.1-3 were based on the continuous purification or cleanup of one reactor coolant system volume per day with zero removal efficiency for krypton, cesium, and xenon, and 99 percent removal efficiency for all other nuclides. Krypton and xenon, being noble gases, are not removed by ion exchange. The mixed resin bed in the purification demin-eralizer will normally operate in the potassium-borate form since potassium hydroxide is used for coolant pH control and since boric acid is used for chemical shim control. Laboratory 7
experiments and operating experience 8 indicate that potassium-saturated resins will not effectively remove cesium. The ref-crenced laboratory experiments also indicate that significant removal efficiencies can be obtained for strontium and barium, and it appears that a removal efficiency of 99 percent should be reasonable for these nuclides.
The referenced experiments further show that yttrium has low removal efficiencies in potassium-saturated resins, and there is additional evidence that molybdenum has low removal efficiencies.
Removal efficiencies of 99 percent were assumed to establish the activity levels for yttrium and molybdenum in the reactor coolant activities listed in Table 11.1-3 of the PSAR.
If no removal of yttrium and molybdenum is assumed, the activities in Table 11.1-3 will increase. However, the effect on activity concentrations released in the circulating water discharge will be only a small l
increase in these values. The referenced operating experience shows that borated resin is very effective in removing iodine.
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REFERENCES 1
Frank, P. W., et al., Radiochemistry of Third PWR Fuel Material Test -
X-1 Loop NRX Reactor, WAPD-TM-29, February 1957 2
Eichenberg, J. D., et al., Ef fects of irradiation on Bulk l'02, WAPD-183, October 1957.
Allison, G. M. and Robertson, R. F.
S., The Behavior of Fission Products in Pressurized-Water Systems. A Review of Defect Tests on l'02 Fuel Ele-rnents at Chalk River, AECL-1338,1961.
4 Allison, G. M. and Roe, H. K., The Release of Fission Gases & Iodines From Defected U02 Fuel Elements of Different Lengths, AECL-2206, J une 1965.
5 Fletcher, W. D and Picone, L.
F., Fission Products f rom Fuel Defec t Test at Saxton, WCAP-3269-63, April 1966.
6 Perry, J. B. and Alcorn, J. M., BURP - A Computer Program for Calculat-ing Buildup and Decay of Radioactive Fission Products, BAW-TM-444, November 1966.
7 Simon, G.
P., et al., The Performance of Base-Form Ion Exchangers for pH Control and Removal of Fission Products from Pressurized Water Reac tors, WAPD-CDA(AD)-528, April 1959.
O Weisman, J. and Bartnoff, B., The Saxton Chemical Shim Experiment, WCAP-2599, Augus t 1964 n,
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