ML20153B507
| ML20153B507 | |
| Person / Time | |
|---|---|
| Issue date: | 10/02/1987 |
| From: | Beckjord E NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Jordan E, Kerr W Advisory Committee on Reactor Safeguards, Committee To Review Generic Requirements |
| References | |
| GL-87-11, NUDOCS 8803220210 | |
| Download: ML20153B507 (4) | |
Text
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8 NUCLEAR REGULATORY COMMIS,SION n
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OCT 2 1987 MEMORANDUM FOR: Edward L. Jordan, Chairman Comittee to Review Generic Requirements William Kerr, Chairman Advisory Committee on Reactor Safeguards FROM:
Eric S. Beckjord, Director Office of Nuclear Regulatory Research
SUBJECT:
REQUEST FOR APPROVAL TO PUBLISH A FEDERAL REGISTER NOTICE REVISING ASB 3-1 0F SRP 3.6.1 With the concurrence of 'the' Director, Office of Nuclear Reactor Regulation, I am transmitting for your review and approval a Federal Register notice announcing a revision of ASB 3-1 of SRP 3.6.1 which eliminates jet impingement effects on essential equipment associated with the arbitrary one square foot break in the break exclusion (superpip)e) zone of main steam and feedwater lines outside the containment (Enclosure 1.
Under this revision, the staff will continue to enforce separation and isolation of essential equipment in the break exclusion zone as the preferred method of providing protection without, however, referring to jet impingement effects.
Thit action to delete the jet impingement effects of the arbitrary one square foot break in the break exclusion zone is closely related to the recent revision of MEB 3-1 in SRP 3.6.2 which eliminated arbitrarily postulated double-ended pipe ruptures (see Generic Letter 87-11, June 19, 1987).
The motivations and technical foundations are the same; however, this present revision is of substantially lesser consequence.
The revision has negligible value-impacts for existir:g plants and no estimated significant costs anJ benefits for future plants; the objective of the revision is to achieve regulatory efficiency and more realistic technical requirements.
Because of these relatively modest objectives, solicitation of pubife comment is not recomended.
A detailed Regulatory Analysis prepared by Lawrence Livermore National Laboratory for this revision is given in Enclosure 2.
A summary and more complete explanation of the action is given in Enclosure 3, which is interded to satisfy the CRGR requirement for a "Summary of Proposed Generic Requirements for CRGR Review."
Eric S. Beckjord, Dt' rector Office of Nuclear Regulatory Research
Enclosures:
As stated 8803220210 871002 PDR REVGP NRCCRCR PDR
f7590-01)
NUCLEAR REGULATORY COMMISSION STANDARD REVIEW PLAN REVISION The Nuclear Regulatory Commission (NRC) is revising section B.1.a.(1) of Branch Technical Position ASB 3-1 in Standard Review Plan (SRP) 3.6.1.
The revision is effective immediately.
This action is estimated as a negligible value-impact revision made only for regulatory efficiency and to introduce more realistic technical requirements.
The text of section E.1.a.(1) which was deleted is as follows:
Even though portions of the main steam and feedwater lines meet the break exclusion requirements of item B.1.6 (sic) of BTP MEB 3-1, they should be separated from essential equipment.
In order for essential equipment to be properly separated, the essential eouipment must be protected from the jet impingement and environmental effects of an assumed longitudinal break of the main steam and feedwater lines.
Each assumed longitudinal break should have a cross sectional area of at least one square foot and should be postulated to occur at a location that has the greatest effect on essential equipment.
l l
l The deleted text erroneously wrote B.1.6 instead of B.1.b.
l l
The new text of section B.I.a.(1) which is now effective is indicated below:
Even though portions of the main steam and feedwater lines mcet the break i
1.
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i 1
[7590-01) i exclusion requirements of item B.1.b of BTP MEB 3-1, they should be separa ted from essential equipment.
Designers are cautioned to avoid concentrating essential equipment in the break exclusion zone.
Essential equipment must be protected from the environmental effects of an assumed nonmechanistic longitudinal break of the main steam and feedwater lines.
Each assumed nonmechanistic longitudinal break should have a cross sectional area of at least one square foot and should be postulated to occur at a location that has the greatest effect on essential equipment.
The essential difference is that jet impingement effects associated with the arbitrary one square foot break are no longer postulated in the break exclusion zone of main stream and feedwater piping outside the containment.
Environmental qualification effects and pressurization effects for structural design resulting from the arbitrary one square foot break are retained in the revision; however, other postulated pipe rupture requirements may control environmental qualification and structural evaluation.
The NRC will continue to enforce separation and isolation of essential equipment in the break exclusion zone as the preferred method of providing protection without, however, postulating iet impingement effects in the break' exclusion zone.
s The regulatory analysis prepared by Lawrence Livermore National Laboratory for this action is available for inspection and copying for a fee at the NRC Public Document Room at 1717 H Street, NW, Washington, DC.
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a f7590-01]-
For additional in' formation concerning ' this revision-td SRP 3.6.1 telephone:
John A. O'Brien, Office of Nuclear Regulatory Research, (301) 443-7854.
Dated at Rockvill'e, Maryland, this day of 1987.
For the Nuclear Regulatory.Comission.
t d
Eric S. Beckjord, Director Office of Nuclear Regulatory Research.
L R
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