ML20195C454
| ML20195C454 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 10/28/1988 |
| From: | Morris K OMAHA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| GL-88-11, LIC-88-950, NUDOCS 8811030110 | |
| Download: ML20195C454 (3) | |
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Omaha Public Power District 1623 Harney Omaha. Nebraska 68102 2247 402/536 4000 October 28, 1988 LIC 88 950 U.S. Nuclear Regulatory Corraission ATTN:
Document Control Desk Mail Station Pl-137 Vashington, DC 20555
References:
1.
Docket No. 50 285 2.
Letter frorn OPPD (R. L. Andrews) to NRC (Document Control Desk) dated March 14, 1988 (LIC 88 145) 3.
Amendment No. 114 to Fort Calhoun Station ' technical Spec-ifications, dated June 23, 1988 4.
NRC Ceneric Letter 88 11 "NRC Position on Radiation Embrittlement of Reactor Vessel Matarials and its Impact on Plant Operations', dated July 12, 1988 5.
Le tte r f rom OPPD (R. L. Andrews) to NRC (Document Control Desk), dated December 21, 1987 (LIC-87 692)
Centlemen:
y SU3 JECT: Response to NRC Ceneric Letter 88 11: NRC Position on Radiation Embrittlement of Reactor Vessel Materials and its Irtpac t on Plant Operations Omaha Public Power District (OPPD) was requested by Generic Letter 88 11 to submit a technical ar,alysis to predict the effect of neutron radiation on reactor vessel materials by utiliring the methods contained in Revision 2 of Regulatory Guide 1.99.
OPPD submitted in Reference 2, the Fort Cf.Toun Technical Specification pressure-teaperature (P T) limits which were reanalyzed using the "Draft" version of Regulatory Guide 1.99, Revision 2.
The results were reviewed and approved by the.iRC with the issuance of Amendment No. 114 (Reference 3) and are applicable through 14 Effective Full Power Years (EFPY).
The RTNDT sM f t rep rted in Reference 2 was 285'F, including the 2o uncertainty, at the 1/4t logtion.,The corresponding reactor vessel inner surface fluence was 1.21x10 n/cm' Since the fluence
- t enua t ion equation in the published Revision 2 changed from the "Draft" Revision 2, the RTNDT shift was reanaly:cd.
The resulting shift at the 1/4t location was also calculated to be 285'F, including the 2a uncertainty, and, therefore, the current Technical Specification P-T curves remain bounding.
The Technical
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Oocumsnt Control Desk LIC 88 950 l
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Specifications will, however, need to be revised to incorporate the new fluence i
attenuation equation in the RTNDT shift trend curve, Technical Specification Figure 2 3.
Also, thecurrentTechnicalSpecificationsstatethatgereactor vessg1innersurfacefluencewhichcorgspondgto14EFPYis1.4x10 i
n/cm. The revised fluonce is 1.21x10 n/cm, which is the fluence that l
was used to calculate the 285'F RTNDT shift included in the current Technical Specifications.
OPPD will submit these changes by December 30, 1988.
Due to the increased shift of RTNDT caused by the use of Regulatory Guide p
1.99. Revision 2, as opposed to methods previously used. OPPD has experienced a i
decrease of the operating window which is common to many plants under the new regulation.
Fort Calhoun Station utilises variable setpoint PORVs in its Low i
j Temperature overpressure Protection (LTOP) system, and therefore the use of
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Revision 2 will not severely impact the operability of the plant. However, OPPD has awarded a contract for an LTOP analysis to be done by Combustion
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Engineering to review system hardware and operating procedures to allow for l
setpoint changes which could reduce the likelihood of LTOP challenges for the Fort Calhoun Station.
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Pressurized Thermal Shock (PTS) calculations were repeated to determine RTPTS 4
j using Revision 2 and submitted in Reference 5.
Based on these calculations, r
l Fort Calhoun vill reach the PTS screening criteria before the expiration date l
of the operating license if Revision 2 is included in the PTS Rule. Therefore, i
j the following actions are being taken by OPPD:
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1)
A DOT 4.3 calculation is being performed by Corbustion Engineering for j
the Cycle 10 flux distribution so that credi may be taken for flux reduction to the beltline regions of the reactor vessel from the Cycle r
10 extreme low leakage fuel management.
2)
Performaace of a Scoping Risk Assessment and/or a Regulatory Guide 1.154 analysis is being pursued for the Fort Calhoun Station. This program is i
I tentatively scheduled to begin in 1989 and finish in 1991.
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8 3)
An extreme low radi.il leakage fuel management study is being planned j
which will further reduce the fluence to the critical beltline region i
materials.
l 4)
OPPD is actively participating in the EPRI Reactor Vessel Embrittlement Management Program which is aimed at resolving roactor vessel embrittle-d ment issues.
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Document Control Desk LIC 88 950 Pa ge 3
' Based on the discussion above, OPPD believes it has taken the appropriate ac.
j tions to fulfill the requirements of Ceneric Letter 8811.
If you have any l
questions concerning this matter, please contact us.
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Sincerely.
/
K. [J. t ris r
Division Manager l
Nuclear Operations
(
KJH/rh c:
LeBoeuf, Lamb, Leiby & MacRae 1333 New ilampshire Avenue, N.W.
l Washington, DC 20036 l
R. D. Martin, NRC Regional Administrator, Region IV E
P. D. Milano, NRC Project Manager P. !!. Harrell, NRC Senior Resident Inspector l
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