ML20076N315
| ML20076N315 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 07/13/1983 |
| From: | TOLEDO EDISON CO. |
| To: | |
| Shared Package | |
| ML20076N293 | List: |
| References | |
| TAC-52416, NUDOCS 8307210314 | |
| Download: ML20076N315 (14) | |
Text
_.
" 3/4.4 REACTOR COOLANT SYSTEM l
l sRUfDOWN AND HCrr STANDBY LIMITING CONDITION FOR OPER/CION f
3.4.1.2 s.
At least two of the coolant loops listed below shall be OPERABLE:
1.
Reactor Coolant Imop 1 and its associated steami generator, 2.
Reactor Coolant Loop 2 and its associated steam generator.
3.
Decay Heat Removal Imop 1,*
- 4.. Decay Best Removal Imop 2.*
b.
At least one of the above coolant loops shall be in operation.**
c.
Not more than one decay heat removal pump may be operated with the sole suction path through DE-11 and DE-12 valess the control power has been removed from the DE-11 and DE --
12 valve operator, or annual valves DE-21 and DE-23 are opened.
I d.
The provisions of Specifications 3.0.3 and 3.0.4 are not applicable.
APPLICABILITY: NODES 3, 4 and 5 ACTION:
a.
With less than the above required coolant loops GFEIABLE, i m ediately initiate corrective action to return the a
required coolant loops co OPERABLE status as soon as possible., or be in COLD SHUIDOWN within 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />.
b.
With none of the abovn required coolant loops in operation, suspend all operations involving a reduction in boron concentration of the Reactor Coolant System and immediately initiate corrective action to return the required coolant loop to operation.
- The normal or emergency power. source may be inoperable' in EDE 5.
[
ff' p*r*ovided (1) no operations are permitted that would causa dilution of The decay heat removal pumps may be de-energized for up to 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> the reactor cooli'nt system boron conegntration, and (2) core outlet f
temperature'is maintained at least 10 F below saturation temperature.
1I
g.,.
hacndment No. }; Z 2 6, 38
- DAVIS-BESSE UNIT 1 3/4 4-2 N
N I
~T<ts LocP htM NOT 8C SGL GCTEb g UML.GSr THG, QQIMAR] SIDE TL=MP E'{2ATvRtE AND PPS3 0(2E APE WITHr# -THE Dt tA1 HEAT PEMOV AL SyrTEM's 1)ETl4N l
coMDI Tsods.
8307210314 830713 PDR ADOCK 05000346 P
PDR _,
4 3/4 4~ REACTOR COOLANT SYSTEM
~
[
~
BASES 3/4.4.1 REACTOR COOLANT LOOPS The plant is designed to operate with both reactor coolant loops in operation, and maintain DNER above 1.30 Juring all normal operations and anticipated transients. With one reactor coolant pump not in operation in one loop, THERMAL POWER is restricted by the Nuclear Overpower Based on RCS Flow and AXIAL POWER IMBALANCE, ensuring that the DNBR will be I
maintained above 1.30 at the maximum possible THERMAL POWER for the number of reactor coolant pumps in operation or the local quality at the point of minimum DNBR equal to 22%, whichever is more restrictive.
DMT#
A w*eees 2, e m 5 aseea..eeee.r eeri t 4ee, ma 4ee re--er:
- ffi;';-t heee -womewei
- :;;tilh,inz deoey heestfbut sing a failure considerations require that at least two loops be OPERABLE.
Thus, if the reactor coolant loops are not OPERABLE, this specification requires two DER loops to be OPERABLE.
Natural circulation flow or the operation of one DER pump provides adequate flow to enst.ve miring, prevent stratification and produce i
gradual reactivity clmnges during boron concentration reductions in the Reactor Coolant System.
The reactivity change rate associated with boron reduction will, therefore, be within the capacity of operator recognition and control.
3/A.A.2 and 3/A.a.3 -SAFETY VALVES The pressurizer code safety valves operate to prevent the RCS from being pressurized above its Safety Limit of 2750 psig.
Each safety valve is casigned to relieve 336,000 lbs per hour of saturated steam at the valve's setpoint.
)
i The relief capacity of a single safety valve is adequate to relieve 4
any overpressure condition which could occur during shutdown..In the event that no safety valves are OPERABLE, an operating DHR loop, con-nected to the RCS, provides overpressure relief' capability and will prevent RCS overpressurization.
During operation, all pressurizer code safety valves must be O' PERABLE to prevent the RCS from being pressurized above its safety limit of 2750 psig. The comoined relief capacity of all of thes'e valves is greater than the maximum surge rate resulting from any transient.
. Demonstration of the safety valves' lift settings wi.11 occur only curing snutdown and will be performed in accordance with the provisions of Section XI of the ASME Soiler and Pressure Code.
tenfaobYe IT hi her than the decay
. En mode 3 cohen Rcs Pressure or 9
- l. hed Temoval sprern's des @n canaliHon Cle. sao Psi 3 and 350*F.)a nnyt yeador coolant tosp provides sufge;ent heat remofat capabthty. rne, remainder Modt 3 as well as m moder 4 and g.gither q.songle rtac1br Coolant loop mr o
DAVIS-BES UNIT 1 B 3/4 4,-l' No. #f,f a. DNR_
loop wIIl be sufAcient far acey heat vmoval; *
-- +
..~.,,n
-m,-,r.ev
-e..
r,
,..,-~,.....,,-w,,
,-n n,,
-a-e c-,..,-,
Docket No. 50-346 l
License No. NPF-3 Serial No. 967 July 13, 1983 Attachment II I.
Change to Davis-Besse Nuclear Power Station Unit 1. Appendix A Technical Specifications Incorporation of Radiological Effluent Technical Specifications (RETS)
A.
Time required to Implement This change is to be effective upon NRC approval of the RETS B.
Reason for Change (Facility Change Request 79-114 Rev. C)
The revision to a Table 4.11-1 to make the notation consistent with the Standard RETS and the deletion of Ce-144 from the list of principal gamma emitters for LLD specifications because of the ability to detect Ce-144.
C.
Safety Evaluation (See Attached)
D.
Significant Hazards Considerations (See Attached)
'1
.1
-d, a
u
.w-
--a
Safety Evaluation This license Amendment Application is to revise previously submitted Radiological Effluent Technical Specification (RETS). The Safety function of the RETS is to monitor effluent from Davis-Besse.
We are changing the turbine building sump sampling frequency from 8 to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> in Table 4.11-1 to make it consistent with the sampling fre-I, i i
quency notation. We are removing Ce-144 from the list of principal gamma emitters for which the LLD specifications apply in the Table 4.11-1 l
Notation. The justification for this is attached and will be incorporated f
into Appendix J of the Offsite Dose Calculation Manual.
i l
I
_1
The lower limit of detection (LLD), as defined in the Radiological Effluent Technical Specifications (RETS) is an "... a priori (before the fact) limit representing the capabilities of a measurement system and not as a posteriori 4
(after the fact) limit for a particular measurement." As defined by this definition applicable to the detection capability for radioactive effluant analysis, the LLD is a statistical analysis of a background spectrum and represents the detection limits for a radionuclide if it is the only radionuclide present above background. LLDs should be determined based on an analysis of a blank (or background) sample, j
However, even with this definition and application of LLD, it can be increasingly difficult to achieve a predesignated LLD value for particular radionuclides as the photon abundance (i.e., decay yield) decreases. To address this problem, specific radionuclides have been identified in the RETS as being the principal radionuclides for which the required LLD aust be met.
For the analysis of samples of liquid radioactive effluents, an LLD of 5 x 10-7 pCi/ml is required. For the principal gamma emitters listed, all have characteristic gammas with energy levels and abundances that provide for sufficient analytical sensitivity yielding LLDs within the required value of 5 x 10-7 pCi/ml - except Ce-144. With a 10.8%
abundance and an energy level of 133.5 kev, being able to meet the LLD of 5 x 10-7 pCi/ml requires optimum conditions--conditions which cannot be repeatedly achieved for an operational radiochemistry program at Davis-Besse.
The low gamma yield is a major factor; however, with an energy level which is located within the Compton continuum, the detection capability for Ce-144 even for a blank, background sample is significantly higher compared with other so-called principal gamma emitters.
The equation for LLD in the Davis-Besse RETS is:
4.66 Sb LD=
E
- V 2.22 + Y
where:
S
=
the standard deviation of the tackground counting rate b
VR/T
=
R
=
background counting rate T
=
counting time E
=
counting efficiency V
=
sample size 2.22 =
ccaversion factor (transformations per minute per picocurie) j Y
=
fractional chemical yield (when applicable) l l
By substitution of typical values in this equation, the LLDs for different principal gamma emitters can be compared.- For analysis of a typical background sample at Davis-Besse, the ratio of the LLDs for Ce-144 and Co-60 is about 5.35; for Ce-144 and Ma-54 the ratio is 8.34.
These large ratios are demonstrative of some of the relative difficulties in achieving an LLD of 5 x 10-7 pCi/ml for Ce-144 compared with other principal gamma emitters.
Examining the equation of LLD, two main factors can be altered in an attempt to improve the detection capability - counting time and detector efficiency.
(Altering sample size is not considered realistic since larger samples would pose operational and standard _ calibration problems.
It can also be shown that increasing sample volume does not strongly influence efficiency for counting on contact with the detector face due in part to sample self-shielding and decreased relative efficiency for the increased volume).
~
s
- ~,
W,
-___.___._.___.___.__m.__
5
LLD improves at best as the square root of the counting time. Therefore, increasing the counting time from 2000 seconds to 5000 seconds would only provide a 1.6 reduction in LLD. A 5000 second count is considered to be a reasonable maximum for radioactive effluent analysis. Having to extend to longer counting times would introduce a potential operational delay without commensurate improvement in detection capability.
An improvement in the efficiency can be accomplished by the use of a more efficient GeLi detector. However, this increased efficiency is negated in part by the corresponding increase in background count rate. A comparison of 5 GeLi detectors with relative efficiencies ranging from 7.2% to 22%
was performed at the University of Michigan *. For a 500 ml sample on contact with the detectors, the 15% relative efficiency detector demonstrated the highest photopeak efficiency in the 80-200 kev range. Even the 10%
relative efficiency detector had a higher photopeak efficiency in this energy range than did the 21% and 22% relative efficiency detectors. Some unexplainable differences may be due to inherent manufacturer specifications; however, a valid conclusion is that increasing the detector efficiency provides little if any improvement in detection capability, especially in the low energy range (<200 kev).
a Therefore, the analysis of effluent samples at Davis-Besse with a 10%
relative efficiency GeLi and a 5000 second counting time provides a detection system that is not only practical for an operational radiochemistry program but can also be considered as representative of state-of-the-art for routine, general purpose radionuclide detection. Since the required LLD of 5 x 10-7 pCi/ml can not be met on a routine basis for Ce-144, this radionuclide is being deleted fron'the list of identified principal gamma emitters for liquid effluents in the RETS (Table 4.11-1, footnote b.).
Therefore,these changes are considered not an unreviewed Safety Question.
- Minnema, D. M. Hudson, C. G. And Jones, J.
D., "A Comparison of Ge(Li) l Detectors with Different Efficiencies for Low-Level General Purpose Counting"; University of Michigan, 1978.
SIGNIFICANT HAZARD CONSIDERATION The attached amendment request for a change to the Radiological Effluent Technical Specification (RETS) does not contain a Significant Hazard. The requested changes are to the RETS (which is under review by the NRC) to revise a Table 4.11-1 to be consistent with the Model RETS and removal of Ce-144 for the LLD specification. The removal of Ce-144 from the LLD as Ce-144 energy level (133.5 KEV) is located within the Compton continium which requires optimum conditions for detection at Davis-Besse.
The granting of the request would not:
1)
Involve a significant increase in the probability or consequences of an accident previously evaluated (10CFR50.92(C)(1).
By not counting Ce-144 there would be no increase or the probability of an accident previously evaluated as other principal gamma emitters for the LLD are counted.
2)
Create the possibility of a new or different kind of accident previously evaluated (10CFR50.92(C)(2).
All accidents are still bounded by previous and no new accidents are involved.
3)
Involve a significant reduction in a margin of safety 10CFR50. 92(C) (3).
This request will maintain the margins assumed in the accident analysis.
Therefore, based on the attached safety evaluation and the above, the requested amendment does not contain a Significant Hazard.
TABLE 4.11-1 RADIOACTIVE LIQUID WASTE SAMPLING AND ANALYSIS PROGRAM Minimum cower Limit Liquid Release Type Sampling Analysis Type of Activity of Detection Frequency Frequency Analysis (LLD) (pCi/ml),
-7 b A.
Batch Wast Eac Batch Eac Batch Principal Gamma 5 x 10 Release Ta k.d f
'~
r I-131 1 x 10
P
-5 One Batch /M M
Dissolved and 1 x 10 Entrained Gases
-5 P
H-3 1 x 10 Each Batch M
c Composite
-7 Gross Alpha 1 x 10
-8 Eac Batch 0
Sr-89, Sr-90 5 x 10 c
Composite
-6 Fe-55 1 x 10 B.
TurbjneBuilding S
Once per Principal Gamma 5 x 10-7 8 Sump Grab Sample 12 Hours Emitters #
-6 I-131 1 x 10
-7 b C.
Condensate Eac Batch Eac Batch Principal Gamma 5 x 10 Demineralizer f
Backwash Emitters I
-6 I-131 1 x 10 1
'0 AVIS-BESSE, UNIT 1
-l
1 TABLE 4.11-1 (Continued)
TABLE NOTATION a.
The LLD is the smallest concentration of radioactive material in a sample that will be detected with 95% probability with 5% probability of falsely concluding that a blank observation represents a "real" signal.
For a particular measurement system (which may include radio-chemical separation):
4.66 s LLD =
b E
V 2.22 Y
where LLD is the lower limit of detection as defined above (as pCi per unit mass or volume);
s is the standard deviation of the background counting rate or b of the counting rate of a blank sample as appropriate (as counts per minute);
E is the counting efficiency (as counts per transformation);
V is the sample size (in units of mass or volume);
2.22 is the number of transformation per minute per picocurie; Y is the fractional radiochemical yield (when applicable);
J It should be recognized that the LLD is defined as an a priori (before the fact) limit representing the capability of a measurement system and not as an a posteriori (after the fact) limit for a particular measurement.
b.
The principal gamma emittars for which the LLD specification will apply are exclusively the following. radionuclides: Mn-54, Fe-59, Co-58, Co-60, Zn-65, Mo-99, Cs-134, Cs-137, and Ce-141.
Other peaks which are measured l
and' identified shall also be reported.
Nuclides which are below the LLD for the analysis should not be reported
-as being present at the LLD level. When unusual circumstances result in-LLD's higher than required, the reasons shall be documented in the semi-l annual Radioactive Effluent Release Report.
t DAVIS-BESSE, UNIT 1 l
o
I correction for low vent exit velocity (m) c
=
y 3
1.5 1
d for I < 1.5 u_
u
=
0 for * > 1.5 4
2 F,
momentum flux parameter (m /sec )
=
(If)
=
S
=
restoring acceleration per unit vertical displace-ment for adiabatic motion in the atmosphere 8.7 x 10-4 sec for i 5 1.5 (E)
-2
-2 for i $ 4.0 (F) 1.75 x 10-3 sec 2.45 x 10-8 sec for i > 4.0 (G)
-2 h
=
height of terrain at distance r in sector of interest (a) downwind distance (a) r
=
I
=
vertical standard deviation of the plume with building wake correction (m) 2 + b_2_ 1/2
=
the lesser of 0
g _
k or
]3G L
l L
i l
2.0 i 1
e
,w
y Lower Limit Of Detection Definition And Application To Detection Capabilities For Ce-144 er -
The lower limit of detection (LLD), as defined in the Radiological Effluent Technical Specifications (RETS) is an "... a priori (before the fact) limit representing the capabilities of a measurement system and not as a posteriori (after the fact) limit for a particular measurement." As defined by this definition applicable to the detection capability for radioactive effluent analysis, the LLD is a statistical analysis of a background spectrum and represents the detection limits for a radionuclide if it is the only radionuclide present above background. LLDs should be determined based on
~
an analysis of a blank (or background) sample.
However, even with this definition and application of LLD, it can be increasingly difficult to achieve a predesignated LLD valum for particular I
radionuclides as the photon abundance (i.e., decay yield) decreases. To address this problem, specific radionuclides have been identified in the RETS as being the principal radionuclides for which the required LLD must be met. For the analysis of samples of liquid radioactive effluents, an LLD of 5 x 10-7 pCi/al is required. For the principal gamma emitters listed, all have characteristic gammas with energy levels and abundances that provide for sufficient analytical sensitivity yielding LLDs within the required value of 5 x 10-7 pCi/ml - except Ce-144. With a 10.8%
abundance and an energy level of 133.5 kev, being able to meet the LLD of 5 x 10-7 pCi/ml requires optimum conditions--conditions which cannot be repeatedly achieved for an operational radiochemistry program at Davis-Besse.
The low gamma yield is a major factor; however, with an energy level which is located within the Compton continuum, the detection capability for Ce-144 even for a blank, background sample is significantly higher compared with other so-called principal gamma emitters.
The equation for LLD in the Davis-Besse RETS is:
4.66 S D=
EV 2.22 Y
DAVIS-BESSE, UNIT 1 J-26
I
- +.
where:
S
=
the standard deviation of the background counting rate b
4R/T
=
R
=
background counting rate T
=
counting time E
=
counting efficiency V
=
sample size 2.22 =
conversion factor (transformations per minute per picoeurie)
Y
=
fractional chemical yield (when applicable)
Py substitution of typical values in this equation, the LLDs for different principal gamma emitters can he compared. For analysis of a typical j
background sample at Davis-Besse, the ratio of the LLDs for Ce-144 and Co-60 is about 5.35; for Ce-144 and Mn-54 the ratio is 8.34.
These large ratios are demonstrative of some of the relative difficulties in achieving an LLD of 5 x 10-7 pCi/ml for Ce-144 compared with other principal gamma emitters.
Examining the equation of LLD, two main factors can be altered in an attempt to improve the detection capability - counting time and detector efficiency.
(Altering sample size is not considered realistic since
[
larger samples would pose operational and standard calibration problems.
L It can also be shown that increasing sample volume does not strongly influence efficiency for counting on contact with the detector face due in part to sample self-shielding and decreased relative efficiency for the increased volume).
ll DAVIS-BESSE,. UNIT-1 JJ-27
{
LLD improves at best as the square root of the counting time. Therefore, increasing the counting time from 2000 seconds to 5000 seconds would only provide a 1.6 reduction in LLD. A 5000 second count is considered to be a reasonable maximum for radioactive effluent analysis. Having to extend to longer counting times would introduce a potential operational delay without commensurate improvement in detection capability.
An improvement in the efficiency can be accomplished by the use of a more efficient GeLi detector. However, this increased efficiency is negated in part by the corresponding increase in background count rate. A comparison of 5 GeLi detectors with relative efficiencies ranging from 7.2% to 22%
was performed at the University of Michigan *. For a 500 m1 sample on contact with the detectors, the 15% relative efficiency detector demonstrated the highest photopeak efficiency in the 80-200 kev range. Even the 10%
relative efficiency detector had a higher photopeak cfficiency in this energy range than did the 21% and 22% relative efficiency detectors. Some unexplainable differences may be due to inherent manufacturer rpecifications; however, a valid conclusion is that increasing the detector efficiency provides little if any improvement in detection capability, especially in the low energy range (<200 kev).
i Therefore, the analysis of effluent samples at Davis-Besse with a 10%
relative efficiency GeLi and a 5000 second counting time provides a detection system that is not only practical for an operational radiochemistry program but can also be considered as representative of state-of-the-art for routine, general purpose radionuclide detection. Since the required LLD of 5 x 10-7 pCi/ml can not be met on a routine basis for Cc-144, this radionuclide is being deleted from the list of identified principal gamma emitters for liquid effluents in the RETS (Table 4.11-1, footnote b.).
i l
- Minnema, D. M. Hudson, C. G. And Jones, J.
D., "A Comparison of Ge(Li)
Detectors with Different Efficiencies for Low-Level General Purpose i
Counting"; University of Michigan, 1978.
1 i
j DBP 4306G i
l DAVIS-BESSE, UNIT 1 J-28
-