ML17347A509
| ML17347A509 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 05/26/1987 |
| From: | Stello V NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | Chiles L SENATE |
| Shared Package | |
| ML17347A511 | List: |
| References | |
| NUDOCS 8706030412 | |
| Download: ML17347A509 (5) | |
Text
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0 Vk o k~*y4 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 tItAY 26
@gal The. Honorable Lawton Chiles United States Senator Federal Building Lakeland, Florida 33801
Dear Senator Chiles:
I am pleased to respond to your May 4, 1987 letter in which you indicated that one of your constituents, Ms. Joan Graff, expressed concern that:
( 1) the recent boric acid leak at Turkey Point Unit 4 has caused corrosion and could possibly lead to a meltdown; and (2) that Florida Power and Light Company (FPL) has refused to test the welds inside the Unit 4 reactor vessel.
In response to Ms. Graff's first concern, I addressed this in detail by my letter to you dated May 7, 1987, which responded to a concern voiced by.
Mr. P.A. Oldfield, another of your constituents, relating to the leak in the reactor coolant system (RCS) of Turkey Point Unit 4.
That leak resulted in the deposition of crystalline.boric acid on the reactor vessel head and surrounding'reas.
I have enclosed the May 7, 1987 response, which describes the event, actions taken by the licensee and the Nuclear Regulatory Commission (NRC),
status of the event, ongoing efforts in relation to the event, and the regulatory requirements and basis for determining the operational safety of the Turkey Point facility.
Ms. Graff's second concern appears to be in relation to FPL's Reactor Materials Surveillance Program.
FPL has not refused to test the reactor vessel welds.
The NRC-approved surveillance program does not require that the Unit 4 weld samples be tested at this time nor have we requested FPL to deviate from their approved schedule.
The surveillance program for Turkey Point Units 3 and 4 in-cludes a set of capsules placed in each reactor; the capsules contain samples of the weld materials and base metals used in fabricating the beltline of the reactor vessel.
During construction, the capsules are placed in the vessel near the wall where they receive neutron radiation representative of that received by the beltline.
In accordance with regulations, the first capsule is with-drawn after several years of operation when its contents have been exposed to neutron radiation at vessel operating temperature.
The specimens are then tested to determine the change in resistance to brittle fracture caused by the radiation.
Subsequent capsules are withdrawn at specified intervals to monitor long-term effects throughout the reactor vessel(s) lifetime.
In 1985 the utility requested, and the NRC agreed to, an integrated surveillance program for Turkey Point Units 3 and 4.
In each vessel there are two capsules containing the critical weld metal, and under the integrated program, the test results from the four capsules will be applied to vessel integrity analyses for both units.
Section II.C of 10 CFR 50, Appendix H, permits an integrated sur-veillance program for reactors at the same or different physical sites.
It appears that Ms. Graff believes that the only source of information about the 870b030412 87052b PDR ADOCK 05000251 PDR]
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t The Honorable Lawton Chiles neutron embrittlement of the materials in a given reactor vessel comes from the test results for specimens irradiated in that vessel as part of its surveillance program.
As noted above, there are a limited number of capsules containing the critical weld material, and the withdrawals are scheduled at specified intervals to monitor the long-term effects throughout the reactor vessel(s) lifetime.
I must emphasize that there is a sound basis for estimating neutron embrittlement besides the information obtained from plant-specific surveillance programs.
Until plants have credible surveillance data of their own (preferably from two or more capsules tested at specified intervals), their submittals for pressure-temperature limits, which take account of radiation embrittlement, are based on knowledge of the chemical composition and the neutron fluence.
Test data from many sources are used which have been characterized according to the critical variables, chemical composition of the material, and neutron fluence.
On these
- bases, pressure-temperature limits have been established for Turkey Point Units 3 and 4 that ensure safe operation, and the susceptibility to the pressurized thermal shock has been evaluated.
The NRC has accepted certain formulas for calculating the degree of embrittlement.
The basis for these formulas is the rapidly growing surveillance data base not only from Turkey Point, but from all power reactors.
A significant margin is added to the calculated result to account for uncertainties.
The NRC has established in 10 CFR 50.61 a screening criterion and identified acceptable means for calculating the reference temperature to judge the condition of reactor vessels at all sites.
At the end of their present licensed life, Turkey Point Units 3 and 4 will be well within the screening criteria for safe operation.
In summary, regarding Ms. Graff's first concern, both the licensee and the NRC staff are performing independent assessments of the effects of the RCS leakage and preparing detailed reports which will provide the bases to determine if Turkey Point Unit 4 is in conformance with its design, as documented in the Final Safety Analysis Report, and can be operated safely within its Technical Specifications.
Regarding Ms. Graff's second
- concern, we certainly do have to be careful about monitoring the integrity of reactor vessels in all operating nuclear power plants.
The nuclear power industry and the NRC have expended considerable effort to ensure that safety margins are maintained by ensuring that the extent of neutron radiation damage is known.
FPL is in compliance with its approved surveillance program and the requirements of 10 CFR 50.61 to ensure reactor vessel integrity for Turkey Point Units 3 and 4.
I trust this is responsive to your request and of assistance in assuring you and your constituents that the Commission's requirements and programs to ensure safe operation of all operating nuclear power plants, including Turkey Point, are based on sound technical requirements.
The actions being taken by the staff in these areas are consistent with the Commission's statutory responsi-bility to ensure that all operating facilities achieve and maintain adequate levels of protection of public health and safety.
The Honorable Lawton Chiles If we can be of further assistance, please do not hesitate to contact us.
Sincerely,
Enclosure:
As stated Victor Stello, Jr.
Executive Director for Operations DISTRIBUTION g
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