ML20215F911
| ML20215F911 | |
| Person / Time | |
|---|---|
| Site: | Washington Public Power Supply System |
| Issue date: | 10/01/1986 |
| From: | Sorensen G WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20215F914 | List: |
| References | |
| RTR-NUREG-0800, RTR-NUREG-800 NUDOCS 8610160417 | |
| Download: ML20215F911 (2) | |
Text
)
m 6,- Q WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968
- 3000 George Washington Way
- Richland, Washington 99352 October 1, 1986 G01-86-0135 Docket No. 50-460 Mr. J. F. Stolz PWR Directorate No. 6 Division of PWR Licensing U. S. Nuclear Regulatory Commission Washington, D. C.
20555
Subject:
NUCLEAR PROJECT N0. 1 NON-MECHANISTIC FAILURES IN MAIN STEAM AND FEEDWATER ISOLATION AREA The design and construction of the Main Steam and Feedwater Isolation Area (MSFIA) high energy fluid system piping has embodied features which provide a high level of assurance against the possibility of a large size piping failure.
These. features were provided in order to meet the criteria of Standard Review Plans 3.6.1 and 3.6.2 of NUREG-75/087.
Included in this category were the design and installation of boundary restraints on the main steam and feedwater piping at the transition point from ASME III, Class 2 to Non-Nuclear Safety (NNS), special pipe forgings at these restraints, simplified piping geometry within the MSFIA and containment penetrations with integrally-forged flued heads.
A planned program to perform augmented in-service inspection (ISI) on the welds within the fluid pressure boundary will further enhance the level of protection provided.
Cuprent SRP criterion, specifically BTP ASB 3-1 of NUREG-0800, states that a 1.0 ft "non-mechanistic" failure be postulated in the - main steam and feedwater system piping and the ensuing jet impingement and environmental effects addressed.
This criterion is directed towards portions of main steam and feedwater piping that have satisfied all of the " break-exclusion" requirements delineated in BTP MEB 3-1 of NUREG-0800 so that environmental considerations on essential equipment can be addressed.
A back-fit of this criterion to the existing MSFIA design at WNP-1 was not practical at the time of publication of NUREG-0800, given the advanced stage of construction.
The MSFIA structure and the internal essential equipment and components are or will be structurally and environmentally qualified to withstand fluid releases from a 4-inch diameter steam line circumferential failure.
Such a failure represents the most severe " mechanistically-derived" break postulated for high energy piping within the MSFIA and is the design basis break for the MSFIA.
8610160417 861001
/
[DR ADOCK 05000460 f f9 PDR kcbeI kcl lCCn$ ISO @
3 a
o Mr. J. F. Stolz Page Two The purpose of this letter is to submit to the NRC for technical review, the specific design features of the MSFIA as outlined in the attached' report regarding WNP-1 position on non-mechanistic piping failures in the MSFIA.
It is felt that-the basic concern of assuring plant safe shutdown through the functioning of essential equipment and components is adequately addressed by these features.
The Supply System is presently involved in a Design Asset Preservation program that consists of the orderly and concise statusing of the design for all facets of WNP-1.
It is extremely important that all existing licensing issues be l
resolved and incorporated into this program For this reason, prompt NRC action is requested on the exclusion of the 1 ft2 "non-mechanistic" break in the main steam and feedwater piping in the MSFIA.
Fifteen (15) copies of Enclosure 1,
'WNP-1 Position on Non-Mechanistic Piping Failures in Main Steam and Feedwater Isolation Area (MSFIA)', are being transmitted.
Enclosed is he $150.00 application fee required by 10CFR170.12.
j f=^
G. C.
orensen, Manager Regulatory Programs GCS:0AF:pd Enclosure cc: N.D.Amaria,UE&C(898)
K.S. West, NRC E. Revell, BPA (399)
N.S. Reynolds, BLCPR-NRC Document Control Desk FDCC