ML20058A299
| ML20058A299 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 11/27/1978 |
| From: | Short T OMAHA PUBLIC POWER DISTRICT |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7812040161 | |
| Download: ML20058A299 (7) | |
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'. V Omaha Public Power District i.23 sanuEv. ouana, utenanna esiO2 = veLEPHONE S36 4000 AnEA CODE 402 t
November 27, 1978 Y
j Director of Nuclear Reactor Regulation i
ATTII:
Mr. Robert W. Reid, Chief j
Operating Reactors Branch No. k U. S. Nuclear Regulatory Co:::missicn Washington, D. C.
205f5 6 f
'5ference: Docket U. 50-285 i
Gentlemen:
Enclosed are forty (h0) copies of the Omaha Public Power District's responses to questiens from members of your staff regarding the Fort Calhoun Station's Cycle 5 reload submittal dated August 3, 1978.
Sincerely, I
T. E.
Short
. Assic,[.antGeneralManager I
TES/KJM:jc::n I
4 EsaC.
j cc: LeBoeur, Lamb, Leiby & MacRae l
1757 "N" Street, N. W.
Washington, D. C.
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i ROU:!D THREE QUESTIO:IS FORT CALHOL"! CYCLE 5 RELOAD APPLICATIO t Q 3.1 HIGHER DF'ISITY iJEL Question From the submittals presented to date, one gets the impression that all fuel in the Cycle 5 core is the High Lensity Fuel which can withstand a IRR of 16.0 KW/ft.
Is this the case?
Answer Yes Q3.2 SIFW A*:D ?EFUELI:IO EORo:t CO:rC?"ITPATIO:I Questien The Safety Injection and ?crueling Water (SIRW) tank. baron concen-tration and the refueling required borch concentraticn has been reduced frora 1900 ppa to 1700 ppm in the Cycle 5 Reload Application. Please ex-plain this change.
Answer The figure of 1900 was derived in Cycle 2.
For Cycle 5, lov te=pera-ture physics calculations were performed and the refueling mode shutdevn calculation was dene in a detailed =ar.ner.
The result of these refined calculations shoved that 1700 pps boron provided adequate shutdown for all cases under censideration.
P Q3.3 CEA I::SERTIO!T DCRI:IG EXCORE LFR !!O!!I"'ORI:!G Question The new Technical Specification requirement, Technical Specification 2.10. L(c), requires that the CEA be withdrawn beyond their Ler.g Term In-sertien Limit (LTIL) when LHR is monitored on execre detectors o0 7.
- ~ hat a
is the purpose of this new restriction?
Ansver The restricticn that CEA's be withdrawn above the Long Ter: Insertion Limit of Technical Specificatien Figure 2-9, Power Dependent Insertion Limit (PDIL), whenever the MR LCO is monitered by excore detectors was added to allev the derivatien of a less limiting LHR LCO ASI " tent" than vould be derived if the nor=al PDIL vas enforced. Without this restriction, the LHR LCO ASI " tent" would be derived assuming the CEA's were inserted to the Trancient Inserti n Limit of the PDIL and the LHR LCO ASI " tent" could te restrictive during normal cjeration. The CEA insertion require-ments have been made more restrictive in order to take the excore LHR LC0 ASI " tent" less restrictive. _
Q 3. k EXCORE LHR LCO ASI "TE'IT" Question In the Cycle 5 Reload Application, you have introduced Technical 6pecification 2.10.h(c) which requires that the CEA be withdrawn beyond the LTIL if the core power distribution is monitored via excores, i.e.,
if Technical Specification Figure 2-6 is in effect. You have stated that Technical Specification 2.10.h(c) was introduced in order to limit CEA insertion while monitoring on excores, and hence give less severe axial shapes with a resultant greater operating flexibility reflected in Tech-nical Specification Figure 2-6.
Yet the Cycle 5 Technical Specification Figure 2-6 appears more restrictive than the Cycle h Technical Specifi-cation Figure 2-6.
Please explain.
Answer It is true that the Cycle 5 Technical Specification Figure 2-6 is more restrictive than the Cycle h Technical Specificatien Figure 2-6.
Technical Specificaticn 2.10.h(c) was introduced in Cycle 5 to prevent Technical Specification Figure 2-6 from being even more restrictive than it is in the Cycle 5 Reload Application.
The primary reason which makes Figure 2-6 more restrictive is that the radial peaks have been increased by h.6% due to waterhole pe1 king. This leads to a slightly reduced maximum allovable power. Although the BOC and ECC axial shapes have changed frcs Cycle 4, these shapes have no significant effect on Figure 2-6.
Q3 5 EXCORE LUR LCO ASI "TEr" KW/Pr LI! FITS Questien It appears that in Cycle h you could only justify assuming the fuel could withstand a LER of 1h.7 KW/ft, but Figure 2-6, the Excore LER LCO ASI " tent" and the Figure 2-6 Scaling Equatien were based on 15.5 KW/ft.
Then in Cycle 5, both Figure 2-6 and the Scaling Equation were based on 14.7 KW/ft while you claimed that your fuel could withstand a LER of 16.0 KW/ft. Please explain these apparent centradicticas.
Answer The Cycle h LHR LCO ASI " tent" was derived based en a peak linear heat rate of 15.5 KW/ft since it was expected that the maximum LHR that could be cbtained using present fuel designs is approximately 16 KW/ft.
A scaling equation was provided to adjust this figure to the LCCA limit of 1h.7 KW/ft for densifying fuel in the Cycle h core. It was verified that this adjusted curve was conservative with respect to a curve which I
could be explicitly derived for ik.7 KJ/ft but vould not restrict opera-tion. For Cycle 5 cperatien, it was decided not to rerun the LOCA analysis necessary to increase the LER LCO to approximately 16 K4/ft and to accept the existing limit of 14.7 KW/ft. It was also determined that the exist-ing Cycle h LER LCO ASI " tent" would be ncn-conservative for Cycle 5 opera-tien. The derivation of the Cycle 5 LHR LCO ASI ". tent" was done explicitly for 14.7 KW/ft in order to minimi:e any operational restrictions and the i
i scaling equation was retained for consistency with the existing Technical i
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Specifications. The combination
- Figure 2-5, Figure 2-6, and the scaling equation form a consistent package in the Cycle 5 amendment.
Q 3. 6 2 A:lD 3 RCP OPERATIO:I Question What is the purpose of Technical Specification Figures 1-5 and 1-6 which refer to 2 and 3 RCP operation?
Answer At present they serve no function, since 2 and 3 RCP operation is pre-cluded by the Technical Specificatica 6.1.
However, it seems reasonable to retain these figures in the Technical Specificaticas for two reasons:
(1)
Deleting them would entail the renumbering of other figures and the references to these figures. This is an error prone procedure and represents unnecessary work for both CPPD and the IIRC.
(2)
If at sone future date 2 and 3 RCP operation is reinstated, the Technical Specificaticn changes vill be relatively minor if Figures 1-5 and 1-6 are already in the Technical Specifi-cations.
Q3.7 TM-LP SET"o!' T Question The '"M-LP Setpoint seems to be defined both in the equations of Tech-nical Specificatien 1.3(h) and in Technical Specification Figure 1-7.
Which of these two is actually applied to the TM-LP RPS Circuitry?
e Answer The equations of Technical Specification 1.3(4) are applied to the TM-LP RFS Circuitry. Figure 1-7 is simply a graphical representatien of the equations of Technical Specification 1.3(h).
Q3.8 EXCORE Mc:rITORIF, Po'4ER LIMS Questica Upon examining Technical Specificatien Figure 2 6, the Excore LER LCO ASI " tent", Figure 2-5, the definition of L, and Technical Specifica-tion 2.10.L(c), the Scaling Equatien for Technical Specificaticn Figure 2-6, it appears that you cannot reach 100", power while monitoring the LHR l
on excores either in C* cle h or Cycle 5 Is this correct?
/
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Ancver Yes, it is correct. The maximum attainable power for Cycles k and 5 while monitoring the LHR on excores is determined as follows:
Cycle h Cycle 5 (1) Defini*, ion of M M=1 M=1 (2) Defir.ition of :I Il = 1 N=1 (3) Definition of L from Technical Specification Figure 2-5 L = lh.7 L = 14. 7 (h) Peak of Excore UIR LCO ASI " Ten t" o f Technical Specifi-cation Figure 2-6 Peak = 1035 Peak = 95%
(5) Scaling Lpaticn Technical Specifi-cation 2.10.h(c)
L L
,,4,.7
, g,.;
1$. 5 14.7 (6) Maximum Attainable Power 'a*hile Mcnitoring LHR cn Excores Pover = 97.7%
Pcwer = 95.0%
Q3 9 PEAKII!3 FAC"'OR LOC's /JID LS3S 's Question The Technical Specificatica figures are nct all labelled in suffi-cient detail that ene can easily ascertain which figure is protecting against what. Please clarify this situation.
Answeg Protective Functica Figure LHR LC33 1h E*lBR LCCS 1-7 LHR LCO 2-6 l
D:iBR LCO 2-7 l
Q3.10 CPERATIO:I 'J!TH LESS "'ILt*; '5': OF CPERA3LE !:lCORE DETECT;R S"'RI:IOS Quentien l
Technical Spe:1ricatien 2.10.3(h), Technical specificatien 2.10 3(5),
Technical Specification 2.10. 3(6), and Technical Specification 2.10.3(7) discuss increased uncertainties to be imposed if less than 75% of Incore h
1 Detector Strings are Operable. Do you expect to find less than 75". of Incore Detector Strings Operab'.e in Cycle 57 Answer No.
All known failed strings are being replaced during this outage, so that to the best of our knowledge at the beginning of Cycle 5 ve vill have 100". of. incore detector strings operable. Based on the Cycle h ex-perienced failure rate of 10% at end of cycle, we anticipate that more than 75". of the incore detector strings will remain operable during Cycle 5
Q3.11 CC:PIERSION FROM EFPD TO !0TD/MTU Question The information I have is the fcllowing:
Licensed Power = 1h20 Y4T Uranium Metal Loading = h8,796 KG 1.0 DAv 1
1.0 EFPH = ik20 K4T
- 1.0 HR
- 24.0 Hht 48,796 MTU Is the above correct?
Answer Yes.
m m
F, fp AND Fj TECHNICAL SPECIFICATICN LIMITS Q3.12 Questien The folleving appears as the reasured LCO limits for peaking factors in Technical Specificatien 1.1.
m m
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' It Cycle L 1.50 1.57 Cycle 5 1 57 1.62 Itf impressien is that these numbers are inputs to the Safety Analysis, not outputs, and hence require no justification with respect to measure-ment uncertainties or computational conservatism credits.
Is this correct?
Ansver Yes. l
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Q3.13 F AND P TECH:lICAL SPECIFICATION LIMIT CURVES ON FIGURE 2-9 XY R
Question With respect to the last questien, =y i=gression is that these whole curves, as well as the 100% Power values of Fpy and Fj addressed in Q312 above are inputs to the Safety Analysis, not outputs, and require no justi-fication with respect to measurement uncertainties or computatienal con-servatism credits. Is this correct?
Answer Yes.
Q 3.1h CONTI!IUCU3 LHR INCORE ALAPf4 LCO Questisn In the present Technical Specificaticn 2.10.4(1)2, a LHR =casurement uncertainty of 10% is assumed. Yet in the Cycle 5 Reload Applicatien it is stated cn page C-12 that the LHR measurement uncertainty used in Cycle 4 was 8%. Please explain this apparent discrepancy.
Answer For calculations dcne in the Cycle k Safety Analysis 8% was used.
Technical Specificatica 2.10.L(1)2 was not modified in Cycle k, and in fact has not been modified since Cycle 1.
This presents no safety ques-tion since assuming 10% rather than 8% =easurement uncertainty provides additicnal conservatism.
Q3 15 LOCAL FUEL "'E!9EPX URE VS LOCAL PC'4ER COPEELATICN Questien In the Cycle 5 Reload Application you indicate that you have incor-porated a new Local Fuel Tetperature vs Local Power Correlation. Please explain hev this new correlation was verified.
Ansver This correlatien is not new in Cycle 5, but has been used and approved by the NRC since Cycle 3.
The references en its verification are the fol-loving:
(1) At-Pover Measurement of Power Ccefficients and Isetber=al Temperature Coefficients, C. F. Sears and P. H. Gavin, ANS Transactions, Supplement 1 to Volu=e 26, Ccaference en Reactor Operating Experience T-10 August 1977, Page 25 i
l (2) Letter frc= T. E. Short, CPPD, to George E. Lear, NRC,10 November 1976.
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