2CAN058105, Forwards Response to Physics Question on Cycle 2 Reload Rept
| ML19347F364 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 05/11/1981 |
| From: | Trimble D ARKANSAS POWER & LIGHT CO. |
| To: | Clark R Office of Nuclear Reactor Regulation |
| References | |
| 2CAN058105, 2CAN58105, NUDOCS 8105190073 | |
| Download: ML19347F364 (3) | |
Text
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ARKANSAS POWER & LIGHT COMPANY POST OFFICE BOX 551 UTTLE ROCK ARKANSAS 72203 (501) 371-4000 May 11, 1981 c ;~
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.D (pig 3,8198I" 2CAN058105 Director of Nuclear Reactor Regulation u.5. toMN"^
ATTN:
Robert A. Clark, Chief 1
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Operating Reactors Branch #3 A'e Division of Licensing
'tgrph-U. S. Nuclear Regulatory Commission Washington, D.C.
20555
SUBJECT:
Arkansas Nuclear One - Unit 2 Docket No. 50-368 License No. NPF-6 Response to Physics Question on the ANO-2, Cycle 2 Reload Report (File: 2-1510)
Gentlemen:
In response to your letter of April 29, 1981, which transmitted questions from the Reactor Physics Section on the ANO-2, Cycle 2 reload report, the attached information is provided.
An advance copy of this information was provided to you prior to May 7,1981.
Very truly yours,
.Mue.YA
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David C. Trimble Manager, Licensing DCT:1p Attachment f82os190o73
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RESPONSE TO NRC QUESTIONS ON ANO-2 CYCLE 2 QUESTION 1 The values of the moderator temperature coefficient (MTC) given in Table 7-2 are extremes that bound the second and future cycle analysis.
Give typical expected values of the MTC for B0C and E0C for full and zero power.
ANSWER Best estimate MTC's for AN0-2 Cycle 2 are compared to the ranges used in the Cycle 2 safety analysis and proposed Technical Specification 3.1.1.4 in Table 1.
TABLE 1 ANO-2 Cycle 2 NTC's (x 10-4 ak/k/ F)
Tech. Spec. &
Safety Analysis Best Estimate Range BOC EOC Full Power
-2.8
+0.0
-0.5
-2.3
+
Zero Power
-2.8
+
+0.5
+0.4 i
Not calculated since it is not a limiting value.
QUESTION 2 In the analysis of the feedwater line break the moderator temperature coefficient is assumed to be zero as opposed to a positive value in the FSAR analysis.
Is this value conservative?
ANSWER As shown in Table 5-1 of the Reload Analysis Report and in the ' response to Question 1, the MTC at full power is not expected to be less negative than -0.5 x 10 -4 ak/k/0F.
A conservative value of zero was chosen for the feedwater line break analysis.
This value is enforced by the proposed revision to Technical Specification 3.1.1.4 (Change #17).
t
- h. QUESTION 3 Technical Specification changes 16, 50, 51 and 52 are related to an increase of the shutdown reactivity margin from 1% ak/k to 5% ak/k to lengthen the available time for operator action.
Give more details on the particular considerations which necessitated this change.
ANSWER The shutdown margin requirement for Mode 5 (cold shutdown) was increased to 5% ak/k to lengthen the available time for operator action in the event of a boron dilution.
In particular, the additional margin is needed in order to meet acceptance criteria for Mode 5 when the RCS is partially drained for maintentnce.
As indicated in Section 7.1.1 of the Reload Analysis Report, the Mode 5 time to lose 2% ak/k shutdown margin with the RCS not drained is 48 minutes.
The time to lose 2% ak/k shutdown margin with the RCS partially drained would be less than 15 minutes.
The corresponding time to lose 5% ak/k shutdown margin with the RCS partially drained is 35 minutes.
QUESTION 4 Technical Specification changes 53, 54 and 55 are related to the introduction of the planar radial peaking factor Fxy in Technical Specification Change No. 6.
Provide the data base and uncertainty analysis which led to the 1.053 uncertainty factor for Fxy.
ANSWER Technical Specification Changes 53 and 55 reflect the 1.053 uncertainty factor for F documented in CENPD-153-P Rev.1-P-A and approved by NRC onJuly2,1950.
(This is noted in Section 5.3.2 of the Reload Analysis x
Report).
Change 54 is a result of changes 6 and 27 where the notation "Fxy" has replaced "Fr".
"Fg" is not the standard symbol for the " planar radial peaking factor" addressed in Technical Specification 3.2.2.
The symbol "Fr" is reserved for the " integrated radial peaking factor".
QUESTION 5 Note, in technical specification change No.17 change "then" to "than" in a, b and c.
ANSWER:
Agreed.
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