ML20070B285
| ML20070B285 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 12/03/1982 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20070B289 | List: |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.D.1, TASK-TM 5211-82-257, NUDOCS 8212090501 | |
| Download: ML20070B285 (2) | |
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GPU Nuclear Corporation u
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e8 Middletown, Pennsylvania 17057 717 944-7621 TELEX 84-2386 Writer"s Direct Dial Number:
December 3, 1982 5211-82-257 Office of Nuclear Reactor Regulation Attn:
Darrell G. Eisenhut, Director Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Sir:
Three Mile Island Nuclear Station, Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 Relief and Safety Valve Testing (NUREG 0737 II.D.1)
NUREG 0737, Item II.D.1, as revised by NRC letter dated September 29, 1981, required pressurized water reactor licensees to conduct testing to qualify the reactor coolant system relief and safety valves under expected operat-ing conditions for design basis accidents and transients.
In order to fulfill this requirement, GPUNC participated in the EPRI PWR Safety / Relief Valve Test Program, which was completed in December of 1981. By letter of April 16, 1982, GPUNC endorsed valve test and justification reports submitted by Mr.
David Hoffman of Consumers Power Company on April 1, 1982. At that time GPUNC indicated that the tests revealed certain instabilities for the Dreseer safety valve tested for some steam and water discharges which required additional evaluation. GPUNC indicated that our preliminary evaluation had concluded that our safety valve performance would be improved when moved from the long inlet configuration to the short inlet configuration and that our analysis of the discharge piping would be performed for the short inlet configuration.
On July 12, 1982, GPUNC provided a letter to the NRC which promised the results of our safety valve discharge piping analysis and endorsed the PORV block valve test report submitted by R. C. Youngdahl on July 1, 1982. The test report indicated satisfactory performance over the full range of expected and f
operating (non-ATWS) conditions for a PORV block valve similar to the one gg installed at TMI-1.
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Consistent with our July 12, letter, enclosed please find a copy of the TMI-l Specific Pressurizer Felief System Piping and Support Evaluation Report.
The report discusses the piping behavior under valve discharge hydrodynamic loading which was analyzed in 3 steps.
1.
Thermal fluid analysis (RELAP 5/ MOD 1 Cycle 14) to determine the state and flow conditions of the fluid.
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Mr. Darrell G. Eisenhut 5211-82-257 2.
Generation of transient flow functions for piping dynamic analysis.
3.
Time history piping structural dynamic analysis (TPIPE 4.2).
The results of the evaluation show that:
a.
Piping for both normal and transient conditions is not overstressed after the addition of a snubber. The redesign is scheduled to be completed and implement by December 31, 1982.
b.
Twenty eight (28) rigid and spring hangers had to be rennalyzed to higher than previously analyzed loads. The analysis.oncluded that with all spring hangers bottoming out, the piping is still not overstressed.
The rigid supports analysis concluded that four pipe supports require minor redesign. The redesign is scheduled to be completed and implemented by December 31, 1982.
The modification to relocate the pressurizer safety valves to the top of the pressurizer is now in construction and is scheduled to be completed by Dec-ember 31, 1982.
GPUNC evaluation of safety valve performance indicated that stable perfornance was only achievable for blowdowns increased above the original specified 5%.
Babcock and Wilcox in conjunction withGPUNC has completed a detailed evaluation of the EPRI ring setting for increased blowdown above 5%.
This evaluation by B&W showed that up to a 20% blowdown can be tolerated without any adverse effect on safety. The 20% value was based on hot leg voiding and did not include any IIPI actuation. The EPRI testing for the TMI-l inlet conditions is bounded by the 20% blowdown. GPUNC has chosen to use the EPRI tested ring setting that showed the most stable valve configuration. The ring settings tested by EPRI were tested at conditions that enveloped the worst case back pressures and are therefore, conservative.
GPUNC has completed its evaluation of the TMI-l PORV block valve and concluded that the valve can be operated, closed and opened for all fluid conditions expected under operating and accident conditions.
Finally, the associated circuitry for the PORV and PORV Block Valve is considered to be IEEE qualified with the exception of the PORV operator which is not qualified for certain accident conditions, but which is not required for accident mitigation.
This letter with attachments and references hereby completes the submittal requirements of NUREG 0737, II.D.l.
Sincerely, fI t
11. D.
!!ukill Director, TMI-l llDil:LWil:vj f cc:
R. C. Ilaynes R. Jacobs J. F. Stolz