ML19221B110
| ML19221B110 | |
| Person / Time | |
|---|---|
| Issue date: | 03/31/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| NUREG-75-087, NUREG-75-087-05.4.11, NUREG-75-87, NUREG-75-87-5.4.11, SRP-05.04.11, SRP-5.04.11, NUDOCS 7907120440 | |
| Download: ML19221B110 (5) | |
Text
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!$hhe't)STANDARD REVIEW PLAN 3*
U.S. NUCLEAR REGULATORY COMMISSION
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OFFICE OF NUCLEAR REACTOR REGULATION SECTION 5.4.11 PRESSURIZER RELIEF TANK REvlEW RESPONSIBILITIES Primary - Auxiliary Systems Branch (ASB) i l
Secondary - Reactor Systems Branch (RSB)
Mechanical Engineering Branch (MEB)
Materisis Engineering Branch (MTE8) l I.
AREAS OF REVIEW The pressurizer relief tank is a pressure vessel provided in typical pressurized water reactor (PWR) primary systems to condense and cool the discharge from the pressuriier safety and relief valves. Discharges froin small relief valves located inside the containment may also be piped to the tank.
Tank capacity is based on a requirement to absorb the pressurizer discharge during a specified step load decrease.
The review of the pressurizer relief tank, as described in the applicant's Safety Analysis Report (SAR), includes the tank, the piping connections from the tank to the pressurizer relief and safety valves, the tank spray system and associated piping, the nitrogen supply piping, and piping leaving the tank to the cover gas analyzer and to the reactor coolant drain tank.
The pressurizer relief tank system is nonsafety-related; the review is primarily directed toward assuring that its operation is con-sistent with transient analyses of related systems and that failure or malfunction of the system could not adversely affect essential systems or components in accordance with applicable criteria.
The review covers the following specific areas:
1.
The seismic design classification of the pressurizer relief tank system.
2.
The quality standards to which the system will be designed, fabricated, erected, and tested.
I 3.
The measures taken in the design to prevent system performance degradation below acceptable levels as a result of failures of other nearby systems or as a result of the tank failure during an anticipated abnormal oc urrence.
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\\17 USNRC STANDARD REVIEW PLAN
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4.
The steam condensing capacity of the tank compared to the largest anticipated plant n;cp load decrease.
5.
The instrumentation provided to measure and indicate pressurizer relief tank pressure, temperature, and liquid level, and to signal the operator in the event of high or low parameter levels.
6.
The tar k rupture disk relief capacity compared to the capacity of the pressurizer relief and safety valves.
7.
The proposed technical specifications, for operating license applications, as they relate to areas covered in this SRP section.
l The revicw of the pressurizer relief tank system will involve secondary reviews per-I formed by other branches. The results of these reviews are used by AS9 to complete overall evaluation of the system. The evaluations performed by others tre as follows:
the RSB will determine that the anticipated and maximum pressurizer rel ef and safety valve discharge rates are acceptable based on a review of the limiting transient and will determine that the piping between the valves and the tank is adequately sized.
The MTEB will verify that inservice inspection requirements are met for system compo-nents and, upon request, will verify the compatibility of the materials of cohstruction with service conditions. The MEB will review the operability of components and confirm that the system is designed in accordance with applicable codes and standards.
II.
ACCEPTANCE CRITERIA g
The design of the pressurizer relief tank system is acceptable if the integrated system design is in accordance with the following criteria:
The rupture disks have a relief capacity at least equal to the combined capacity of the pressurizer relief and safety valves with sufficient allowance for rupture disk tolerance.
2.
The pressurizer relief tank volume and the quantity of water initially stored in the tank should be such that no steam or water will be released to containment under any normal operating conditions or anticipated abnormal occurrences. The initial temperature of water inside tank should be assumed to be no lower than 120 F.
3.
The pressurizer relief tank and rupture disk should be designed for full vacuum so that the collapse of the tank will not occur if the contents are cooled following a discharge of steam without the addition of nitrogen.
I 4.
High temperature, high pressure, high and low liquid level alarms for the pres-surizer relief tank have been provided.
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5.
Regulatory Guide 1.26, as related to the quality group classifications for compo-nents and systems.
6.
Regulatorv Guide 1.29, item c2, with regard to the location of the tank in relation to other plant systems should be such that the plant safety-related systems would not be endangered in the event of a tank failure.
For those areas of review identificd in subsection I as being the responsibility of other branches, the acceptance criteria and their application are contained in the SRP sections corresponding to those branches.
III. REVIEW PROCEDURf5 The procedures below are used in the construction permit (CP) review to determine that the design criteria and bases and the preliminary design described in the SAR meet the acceptance criteria given in subsection II.
For operating license (OL) reviews, the l
procedures are used to verify that the initial design criteria and bases have been apprcpriately implemented in the final design.
Upon request from the primary reviewer, the secondary review branches will provide input for the areas of review stated in subsection I.
The primary reviewer obtains and uses such input as required to sssure that this reviaw procedure is complete.
I The reviewer selects and emphasizes material from this SRP section, as may be appro-priate for a particular case. A determination will be made as to whether the pressur-izer relief tank system or portions thereof are safety related.
In confirming this design aspect, an analysis is made in which it is assumed that any system pipe fails or component malfunctions or fails in such a manner as to cause maximum damage to other equipment located nearby.
The system will be considered nonsafety-related if its failure does not affect the ability of the reactor facility to achieve and maintain safe shutdown conditions.
1.
The SAR is reviewed to establish that the pressurizer relief tank system descrip-tion and related diagrams clearly delineate system operation and the system capability to ac:ept the steam flow released from the pressurizer for step load decreases. Tre reviewer examines the adequacy of the design in terms of the seismic design classification (Regulatory Guide 1.29), quality group classifica-tion (Regulatory Guide 1.26), and conformance with industry standards. Where necessary, the review will include the requirements for system testing, minimum performance, and surveillance requirements.
2.
The SAR is reviewed to determine that the rupture disks on the relief tank have a relief capacity at least equal to the combined capacity of the pressurizer relief and safety valves. The reviewer determines that the tank design pressure provides a conservative margin above tne calculated pressure resulting from the maximum design relief and safety valve discharge, i.e., the maximum surge resulting from 5 4.11-3 Pev. 1
complete loss of load.
T' reviewer ver:f#es that the tank and rupture disks are l
designed for full vacuum, o as to prevent tank collapse if the contents are cooled following a discharge without nitrogen being added.
3.
The pressure suppression capability of the system is reviewed to assure proper system operation. This aspect of the review is similar to the evaluation of the vent clearing and vent flow model for presse e suppression containment systems.
The review includes such effects as dynamic loadings and oscillatory behavior of the steam slug in the discharge line.
The RSB will verify the mass and energy blowdown data to evaluate the above effects.
4.
The piping and instrumentation diagrams are reviewed to verify tha' high tempera-ture and pressure alarms and high and low liquid level alarms have been provided for the pressurizer relief tank.
I 5.
The reviewer verifies that the system will function following anticipated abnormal occurrences. The reviewer evaluates the failure modes and effects analysis presented in the SAR to assure function of requi ed compcnents, traces the avail-ability of C,ese components on system drawi;.gs, and checks that the SAR informa-tion contains verification that minimum system flow and heat transfer requirements are met for each degraded situation over the required time spans. For each case, the design will be acceptable it minimum system requirements are met.
6.
The reviewer determines that failt e of the pressurizer relief tank system or portions of the system not designed to sein'ic Category I, and which are located cIJse to safety-related systems, will not as a result of their failure preclude essential operations of these safety systems. R2ference to the general arrange-ment and layout drawings for structures and systems will be necessary.
7.
The reviewer determines that other systems inside containment are protected from the effects of high energy line breaks and moderate energy leakage cracks in the pressurizer relief system. Layout drawings are reviewed to assure that other systems are not located close to the pressurizer relief system, or that protection from the effects of failure will be provided. The means of providing such protec-tion will be described in Section 3.6 of the SAR and the procedures for reviewing this information are given in the corresponding SRP sections.
l IV.
EVALUATION FINDINGS The reviewer verifies that sufficient information has been provided and his review supports conclusions of the following type, to be included in the staff's Safety Evaluation Report:
"The pressurizer relief tank system includes components and piping such as the pressurizer relief and safety valve connections to the tank, the relief tank spray system piping, the nitrogen supply piping, and piping leaving the tank to the k pki 180 Rev. 1 5.4.11-4 I
cover gas analyzer and reactor coolant drain tank.
[The review has included the l
applicant's proposed design criteria and design bases for the pressurizer relief tank system, the adequacy of those criteria and bases, and the requirements for performance of safety-related functions of the system during normal, abnormal, and accident conditions. (CP)] [The review has included the applicant's analysis of the manner in which the design of the pressurizer relief tank and supporting systems cor' arm to the proposed design criteria and design bases. (OL)]
"The basis for acceptance in the staff review has been conformance of the appli-cant's designs, design cr teria, and design bases for the pressurizer relief tank and supporting systems to applicable regulatory guides, branch technical positions, and industry standards.
"The staff concludes that the design of the pressurizer relief tank system conforms to all applicable regulations, guides, staff positions, and industry standards, and is acceptable."
V.
REFEPENCES 1.
Regulatory Guide 1.26, " Quality Group Classifications and Standards."
2.
Regulatory Guide 1.29, " Seismic Design Classification."
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