ML20239A478
| ML20239A478 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 09/15/1987 |
| From: | Heitner K Office of Nuclear Reactor Regulation |
| To: | Calvo J Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8709170365 | |
| Download: ML20239A478 (5) | |
Text
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Dacket No. 50-267 l
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l MEMORANDUM FOR:
Jose A. Calvo, Director Project Directorate - IV
% 1ET Division of Reactor Projects - III, Undl[
IV, V and Special Pr'ojects 1
FROM:
Kenneth L. Heitner, Project Manager Project Directorate - IV Division of Reactor Projects - III, l
IV, V and Special Projects
SUBJECT:
SUMMARY
OF MEETING WITH PUBLIC SERVICE COMPANY OF COLORADO TO DISCUSS FAILURE OF FORT SS VRAIN CIRCULATOR C-2101 - SEPTEMBER 11, 1987 ST.
l 1
RE:
- 1) Licensee Event Report 87-018 dated August 28, 1987 (P-87300)
- 2) Preliminary Report of Helium Circulator S/N C-2101 1
Damage and Justification for Returning to Power Operation (Attachment 1) l The purpose of this meeting was to discuss the failure of Fort St. Vrain l
circulator S/N 0-2101, and the licRp,to the NRC in Reference 1.see's program to recover fr 6
failure.
This failure was reported The licensee's l
l preliminary report on this failure is Attachment 1 to this meeting summary.
Theattendee'satthismeetingarelistedinAttachment{.Thismeetingwas i
held at the NRC Region IV office in Arlington, Texas.
2 1
ThelicenseerevieweghebackgroundoftheFortSt.Vrainheliumcirculators.
The four circulator 5gonsist of a single stage helium compressor on a single i
shw r{ driven by a steam turbine or a pelton wheel.y i
l l
h The circulated were originally designed for a 30 year wear free life.
The original machine used a number of stainless steel materials in its anigin h design; in particular, in some of the bolting that has now failed.
In order to perform its safety function, the machine must be capable of starting and continued operation on high pressure water.
l In the transient that led to discovery of the failure, the machine apparently tripped when high wobble caused the plant protective system to sense an "over speed" condition and trip the circulator.
Subsequent 4yghen it was discovered that the secondary penetration seal was leaking excessively, the licensee decided to replace this circulator with the spare machinec i
9e
_ At the time of removal, hardware ejected from the machine was found in the inlet and exhaust piping.
These findings are discussed fully in Attachment 1.
a f
Subsequent to removal of the machine and partial disassembly at GA Technologies j
l in San Diego, California has clarified some of the failures.
The j
failure [includeboltingthatholdsinplacethesteamlabyrinthandattaches I
the steam scroll to the bearing assembly.
I The licensee' has performed metallurgical analysis of parts from the failed 3ke circulator.
The presentation material fro'm this analysis is Attachment 3 to S *H b this report; m c4 q g mugy
((
b.)The key conclusion from this analysis is the stress corrosion cr cking was f
found in the failed bolting materials.
However, th@contQrL#7i (s) leading s to the failures have not been identified, lhe licensee stated that the%3/4 inch) bolts were of a high strenoth material und wene had a preload of about 120,000 psi.
This preload was ba(Id on tightening tongue, and was within code o H w blct, A l
In further discussion, the staff noted that tightening tongue is not always accurately reflected in preload, and that highly stressed components, such as these bolts would likely be sensitive to this type of failure.
The staff also requested detailed phot Q raphs of these failures be provided.
The licensee is continuing to perform evaluations of the failure and related l
This includes questions:
,,.. i,.,.,. e n n#l l
1 b,P -
A failure effects analysis for the failed bolting l
- An analysis of consequences of loose parts ejected from the machine
- A review of the history and previous problems with all 5 circulator machines, and A more detailed review of previous materials problems.
These evaluations are underway, and other supplemental evaluations are planned.
The licensee stated that continued operation of Fort St. Vrain was justified, even though the failure found in circulator SN C-2101, were likely to occur eventually in tt;e other circulators.
The basis for continued operation was based on the following:
1)
The failed circulator had been replaced.
The results of the failure analysis to date had been presented to the staff.
2)
A more thorough evaluation was being carried out with the goal of having a final evaluation in 120 days from this meeting date.
3)
Increased on-line monitoring of the circulator wobble output on a daily basis, or on significant speed increases.
Other performance parameters would also be trended.
4)
Operation above 35% power would be on all 4 circulators.
If another circulator failed, the licensee would shutdown the reactor.
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5)
When the evaluations noted above are completed, the licensee would prepare a specific plan of action to correct the-condition in all circulators.
At this time, another meet'ing would be held with the staff, to review these proposed actions.
6)
Following thc above evaluation, the licensee would reevaluate the current circulator surveillance requirements, and propose a suitable amendment to the plant's Technical. Specifications.
Based on the above, the staff stated that they concurred with the licensees proposal.to continue reactor operation until all of the necessary evaluations were complete.
However, the staff noted that it's concurrence would only be for the next six months, and the licensee should make every effort to maintain the above schedule, the staff also requested that the licensee provide a summary of its commitments to the staff, and the staff would respond with a written Safety Evaluation.
The staff stated that the reactor may be returned to power operation as soon as the restart commitments are complete.
Kenneth L. Heitner, Project Manager Project Directorate - IV Division of Reactor Projects - III, IV, V and Special Projects Attachments:
As stated DRfR
_____________m__.__
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' Attachment 2 Attendees at 9/11/87 PSC/NRC Meeting On Circulator j
Failure and Recovery a
Name Title and Organization g
[{
g J. P. Jauclon Chief, PSA, RIV j
J.E.[agliafdo Chief, Reactor' Project Branch R. E. Farrell Sr. Resident Inspector, R-IV
~
R. E. Ireland Chief, Eng. Sect. R-IV F.B.J h Litio^
NRR Mat. Eng. Branch 1
E. B. Tomlinson NRR - Project Manager -
R. C. Stewart Reactor Inspector USNRC P.S.Ch$ck Dep. Reg. Administrative IV NRC V. J. Barbat Mfg. Eng. Manager GA R. T. Maxwell Project Engr. - QA GA Tech. Inc.
J. R. Reesy Staff Assistant PSC R. L. Hellner Materials Eng. Coord. QA PSC Don Warembourg Mgr. Nuc. Engrg PSC M. H. Holmes Nuclear Licensing Mgr.
PSC l
H. L. Brey Mgr.'Nuc. Lic. & Fuel PSC M. E. Niehoff Nuclear Design Mgr.
PSC 4
R. L. Craun Nuclear Site Eng. Mgr.
PSC C. H. Fuller Station Manager PSC-R. h. Williams, Jr.
V. P. Nuclear Operations PSC Jim Eggekroten Supt. Technical Services Engrg.
PSC Tom Erlewine Engineer PSC J. M. Gramling Supervisor, Nuclear Licensing-PSC Operations (The following persons attended this meeting via a telephont hookup).
K. L. Heitner NRC/NRR/PD-IV J. A. Calvo NRC/NRR/PD-IV n
- e. -.
[gh C. D. Sellars NRC/NRR/DEM S T W. Hazelton NRC/NRR/DE33 S1 I. Bukulmez IAEA s
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